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Fossil Fuels
Experimental Analysis of Scale Inhibitors Retention in Carbonate Formations for Application in Squeeze TreatmentsClick to copy article linkArticle link copied!
- Khosro Jarrahian*Khosro Jarrahian*Email: [email protected]. Tel.: +44 (0) 131 451 4583.Flow Assurance and Scale Team (FAST), Institute of GeoEnergy Engineering (IGE), Heriot-Watt University, Edinburgh, EH14 4AS, U.K.More by Khosro Jarrahian
- Morteza AminnajiMorteza AminnajiDepartment of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, M1 3AL, U.K.More by Morteza Aminnaji
- Alexander GrahamAlexander GrahamFlow Assurance and Scale Team (FAST), Institute of GeoEnergy Engineering (IGE), Heriot-Watt University, Edinburgh, EH14 4AS, U.K.More by Alexander Graham
- Kenneth SorbieKenneth SorbieFlow Assurance and Scale Team (FAST), Institute of GeoEnergy Engineering (IGE), Heriot-Watt University, Edinburgh, EH14 4AS, U.K.More by Kenneth Sorbie
Energy & Fuels
Cite this: Energy Fuels 2022, 36, 4, 1776–1791
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Abstract
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In this work, static adsorption/precipitation (Γ/Π) experiments were conducted for two widely used scale inhibitors (DETPMP and VS-Co) using two different size fractions of Moroccan calcite (315–500 and 125–250 μm) to study the effect of particle size on the “apparent adsorption” of these SIs onto carbonate. The reason for performing these experiments at two particle size ranges was to determine whether the relative surface area to volume ratios (as presented as particle size) would affect whether the precipitating SI–Ca complex forms as a “skin” on the mineral surface and, if so, to determine whether this “skin” could affect the further interaction between the SI and the carbonate mineral by a “surface poisoning” effect. The results of both environmental scanning electron microscopy/energy dispersive X-ray analysis (ESEM/EDX) and direct particle size analysis (PSA) clearly showed that no (or very little), such surface deposition or coating around calcite grains occurred for either of these SIs. Essentially, the results for both particle sizes were qualitatively the same for each of the SIs. The DETPMP retention showed coupled Γ/Π behavior, which was predominantly precipitation at [DETPMP] > 100 ppm and was quantitatively almost the same for both calcite particle sizes. Likewise, the results for VS-Co were quantitatively almost identical for both particle sizes and the retention was predominantly via adsorption up to [VS-Co] ≈ 3000 ppm, with some small degree of precipitation at higher concentration observed. The rather different behavior of DETPMP and VS-Co may be ascribed to different functional groups having different pKa values and strengths of SI–Ca binding. Both sets of static adsorption/precipitation experimental results for DETPMP and VS-Co on each calcite particle size fraction were also predicted using a previously published model.
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License Summary*
You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below:
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License Summary*
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Copyright © 2022 American Chemical Society
1. Introduction
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One of the common problems in oil production systems is the deposition and buildup of various inorganic scale precipitates (e.g., BaSO4, CaCO3, etc.). (1−7) These scale deposits can have a highly damaging effect on production performance if they are not properly treated and can be formed in the oil/gas reservoir itself or anywhere in the production system, including upstream, midstream, and downstream, for example, production tubing, pumps, heat exchangers, chokes, and valves. (8−11) One of the most common ways of preventing mineral scale deposition is by the deployment of chemical SIs in a process called a “squeeze” treatment. (12−17) In general, the squeeze process (Figure 1) involves the cessation of flow at a production well and the pumping of a preflush solution (0.1% v/v inhibitor in KCl or injection quality seawater, also containing 20% v/v of a mutual solvent in some applications), followed by the selected scale inhibitor (normally in the concentration range of 5% to 20% v/v in KCl or injection quality seawater), and finally, an overflush stage (using inhibited seawater or KCl) into the well. (18,19)
Figure 1
Figure 1. Schematic of the three principal scale squeeze treatment stages. Reproduced with permission from ref (18). Copyright 2020 American Chemical Society.
When the SI is injected into the formation rock near the wellbore, it is retained within the porous medium. Once the well is brought back onto production, the retained SI is desorbed/redissolved, depending on the retention mechanism, into the stream of produced water. To avoid consuming high volumes of chemical, the SI must prevent or reduce scale formation at substoichiometric levels, that is, at the operating threshold concentration of the SI, which is known as the minimum inhibitor concentration (MIC). As a general rule, the greater the SI retention in the near-wellbore region, the longer the potential squeeze lifetime (measured in the volume of water produced with a [SI] ≥ MIC) that can be achieved. (10,20−26) In scale inhibitor squeeze treatments, the main mechanisms of SI retention within the reservoir formation are through adsorption, (27−30) precipitation, (31,32) or a combination of these two, that is, coupled adsorption/precipitation (denoted Γ/Π).
Adsorption occurs through an electrostatic attraction or physical adsorption between the inhibitor and formation mineral surface. This process is described by an adsorption isotherm, Γ(C), and this governs the squeeze lifetime in an adsorption squeeze treatment. Recently “precipitation” squeezes have been proposed and trialed in the field to increase squeeze lifetimes beyond that attained by pure adsorption. (33−35)
The mechanisms of adsorption (Γ), precipitation (Π), and coupled adsorption/precipitation (Γ/Π) have been investigated using various modeling approaches by many researchers. (36−42) The early mechanistic investigation on SI retention was performed by Vetter, (36) who concluded that the “adsorption isotherms” of SI on sand particles at various pH values and low temperature were more or less indistinguishable, and that there was a small increase in the amount of adsorption as the solution pH was raised. Sorbie et al. (43) studied the effect of pH, temperature, and [Ca2+] on the retention of phosphonate SIs in both crushed and consolidated sandstone. They observed an increasing of SI adsorption on the crushed rock with temperature. In addition, the adsorption of inhibitor was shown to clearly depend on both the [Ca2+] and the solution pH, since the adsorption of diethylene tetra-amine penta(methylene-phosphonic acid) (DETPMP) depends both on the state of SI dissociation and Ca2+-bridging. Tantayakom et al. (44) studied a Ca-ATMP (a phosphonate scale inhibitor) precipitation in the presence of magnesium ion. They concluded that the molar ratio of divalent cations to ATMP molecules in the precipitate increased with increasing pH of the precipitating solution. In addition, they found that squeezing pH0 7 brines containing ATMP and high Ca ions would generate a desirable precipitated product, but precipitation likely would occur faster than desired.
Tomson et al. (39) presented results on the interactions between SI and carbonate-rich formation rocks in which they described the two main mechanisms governing the SI retention in carbonate reservoirs: (a) the precipitation of SI–Ca2+ because of the increase/decrease in [Ca2+] generated through calcite dissolution and (b) the formation of a surface “skin” of the SI–Ca complex, which then led to a reduction in carbonate dissolution. Kahrwad et al. (23) developed a model that shows the dependence on the m/V ratio if coupled adsorption/precipitation is occurring in the sandstone/DETPMP system and showed that apparent adsorption increases as the pH of DETPMP solutions increases. At pH0 4, only pure adsorption is observed, whereas, at pH0 6, coupled adsorption/precipitation is the dominant mechanism of DETPMP retention. Ibrahim et al. (34) carried out a series of static adsorption/compatibility experiments for a range of phosphonate SIs on various mineral substrates present in sandstones, for example, quartz, kaolinite, siderite, etc. They showed that pure adsorption occurred at low [SI] and the “adsorption isotherm” could be used to correctly describe the SI/mineral retention mechanism, while the coupled Γ/Π retention mechanism was dominant at high [SI] (and elevated Ca2+ concentrations) and a coupled Γ/Π model would be used for most phosphonate SI/mineral systems.
Carbonate rocks provide a much more chemically reactive substrate than sandstone reservoirs and so the scale inhibitor retention mechanism can be more complex than simple adsorption. (9,33,45,46) In carbonate formations, scale inhibitors such as DETPMP (which are often deployed in an acidic form) may react with the formation and form precipitated complexes, that is, as sparingly soluble calcium salts of the SI as reported by Tomson et al. (39) Precipitating of the SI in this way can result in longer scale squeeze lifetimes and, hence, can give an improved efficiency of SI deployment. Indeed, even fully neutralized inhibitors react with carbonates to form precipitates since the SI species are generally strong chelators for divalent ions, such as Ca2+. Baraka-Lokmane and Sorbie (9) studied scale inhibitor/carbonate systems by performing a series of core floods in carbonate cores with DETPMP as the SI. They concluded that the higher the concentration of SI and lower the pH, the more calcium dissolution was observed (from the [Ca2+] effluents), and there was a decrease in the [Mg2+] effluent concentration corresponding directly to the increase in the [Ca2+]. In addition, the core permeability (k ∼ 600 mD) increased in all cases indicating that the stimulation effect through calcite dissolution was greater than the permeability reducing effect induced by the deposition of (Ca and Mg) phosphonate salts and finally the lowering of the injected SI solution pH was more important than an increase in the SI concentration for improving the SI adsorption in the core. Jarrahian et al. (46) carried out coupled Γ/Π experiments for two types of widely used polymeric SI on two common carbonate rocks (calcite and dolomite). It was found that poly phosphino carboxylic acid (PPCA) retained more on calcite than on dolomite and that the PPCA retention reduced as the solution pH was lowered. In the P-functionalized copolymer (PFC)/carbonate system the behavior was the opposite to that for PPCA, that is, PFC showed higher retention on dolomite than calcite. Jarrahian et al. (33) summarized the Γ/Π experimental results for 5 widely used SIs (DETPMP, PPCA, PFC, polyhydric alcohol phosphate ester (PAPE), and sulfonated polyacrylic acid copolymer (VS-Co)) on three common carbonate mineral substrates (calcite, dolomite, and limestone). The findings from this work were as follows: (a) in the polymeric SI (PPCA, PFC, and VS-Co) cases, greater retention was observed for all 3 carbonates at lower solution pH values. This was because of the increase in divalent cations concentration (Ca2+ and Mg2+) generated in situ through rock dissolution, which enhanced the complexation process of SI with divalent cations (SI-M2+ complex), and (b) for phosphonate (DETPMP) and a phosphate ester (PAPE) SIs, a higher retention of SI was found at higher solution pH levels. This was due to the greater level of SI dissociation and also more functional groups available for precipitation of SI with M2+. (c) The polymer VS-Co/dolomite system mostly showed pure adsorption with only a very low amount of precipitation; this was attributed to the presence of sulfonate groups (low pKa), and (d) polymeric inhibitors retained at their highest level on calcite (highest relative calcium content), followed by limestone and then dolomite; (e) for the phosphonate and phosphate ester SIs cases, the highest retention levels were observed on dolomite (higher final solution pH and more SI dissociated), followed by limestone and calcite. (f) For all SI types, higher retention (more precipitation, Π) was observed at elevated temperatures. At lower temperatures, the pure adsorption region was larger for all SIs.
Extensive research has been conducted on the apparent adsorption of scale inhibitors under different operational conditions (temperature and pH) and mineralogy compositions (sandstones and carbonates). However, there is still a gap in our knowledge on the effect of particle size of the carbonate mineral fractions on the retention of scale inhibitors. The aim of this study is to investigate the impact of particle size on the retention of different scale inhibitors (DETPMP and VS-Co as representatives of phosphonate and polymeric scale inhibitors, respectively) in carbonate porous media. This has been done by performing a range of “apparent adsorption” experiments, where we plot the apparent adsorption (Γapp) versus final SI concentration (Cf). (23) It has been shown here conclusively where the system is in pure adsorption (Γ) and where it is coupled adsorption/precipitation (Γ/Π). (47−50) When the apparent adsorption results (Γapp) are plotted versus final scale inhibitor concentration (Cf) as a function of mass/volume ratio (m/V, where m is the mass of substrate (carbonate mineral) and V is the solution volume), at low concentrations, scale inhibitor is retained dominantly by pure adsorption and the adsorption results simply “move along” the adsorption isotherm and do not depend on the (m/V) ratio. However, at higher concentrations, the adsorption results are clearly deviating from the adsorption isotherm, the inhibitor is retained mostly by precipitation. In other words, the scale inhibitor interacts with divalent cations, mainly Ca2+, and the SI_Ca complex is precipitated out. This method was applied in this work to analyze such apparent adsorption experiments. (23,33,34) The current experiments in this paper are carried out deliberately in the “initial stages” of a squeeze to determine the precise balance of adsorption (Γ) and precipitation (Π), which cannot be determined directly in flow experiments.
A range of apparent adsorption results (Γapp vs Cf as functions of m/V) is presented for two SIs (DETPMP and VS-Co) on calcite substrates with different particle sizes. These results also show the corresponding levels of final [Ca2+] and pH for every apparent adsorption experiment. This information is supplemented by the study of the formed precipitates using ESEM/EDX and particle size analysis (PSA). (46) These techniques revealed direct information on the morphology of any precipitates formed, that is, whether they are formed as free crystalline (or amorphous) precipitates or whether they form as “coated structures” on the surface of the calcite grains. The EDX measurements also yield an approximate chemical composition of the precipitates; for example, establishing the presence of phosphorus (P from the SI) and Ca, and in what approximate (P/Ca) atomic ratios. (33,45)
2. Experimental Methods and Materials
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2.1. Experimental Procedure
Static adsorption/compatibility experiments were carried out to differentiate between the pure adsorption (Γ) and coupled adsorption/precipitation (Γ/Π) behavior of SIs on carbonate mineral in a North Sea seawater (NSSW) brine. A stock solution of SI with 10 000 ppm was initially prepared and used to make the different SI concentrations in the experiments. Initial SI concentrations of 50, 100, 500, 2000, and 4000 ppm were used in all the experiments for DETPMP. Higher initial concentrations of VS-Co were used at 1000, 2500, 5000 and 10 000 ppm; this was done since the VS-Co was analyzed by a matrix-matched Hyamine method using an ultraviolet spectrophotometer that requires higher concentrations for better accuracy. The pH was measured for all the stock solutions and while it was later adjusted to an initial pH of 4 for the solution with DETPMP, the experiment with VS-Co was conducted at natural pH (no pH adjustment to specific value) of the [VS-Co] solution.
For the static apparent adsorption tests, the experiments were conducted using two different masses of carbonate mineral (Moroccan calcite) (m = 5 and 10 g) for a fixed volume of solution (V = 0.04 L), which result in two different values of the m/V ratio. Corresponding compatibility experiments (with no mineral present) were carried out to establish whether the inhibitor is fully compatible with the test brine (in this case, with NSSW). Thus, any reduction in SI concentration for this test is due to the incompatibility between SI and NSSW, that is, it results in the formation of SI/Ca2+ precipitation. (32,34,45)
While Figure 2 presents a simple schematic of the static adsorption/compatibility test, the main steps with their details in the experimental procedure are as follows:
| 1. | Prepare NSSW brine by dissolving the relevant salts in distilled water, and subsequently, filter this brine through a 0.45 μm filter paper. | ||||
| 2. | Prepare a 10 000 ppm of SI stock solution in the test brine and further dilute to appropriate SI concentrations for the apparent adsorption test in the same test brine in which result in initial concentrations of 50, 100, 500, 2000, and 4000 ppm for DETPMP, and 1000, 2500, 5000, and 10 000 ppm for VS-Co. | ||||
| 3. | Record the pH and then adjust the pH of all stock solutions (blanks and SI/SW samples) to the required initial test pH value: that is, pH0 4 for DETPMP and leave VS-Co at its natural solution pH. | ||||
| 4. | Prepare two sets of plastic bottles: one for apparent adsorption (contains mineral substrate, calcite) and the other set for compatibility testing (no mineral present). Prepare duplicate sample bottles for each test condition for adsorption but only one for compatibility. | ||||
| 5. | Weigh samples of mineral substrate into appropriately labeled bottles (m = 5 and 10 g) for each size fraction (125–250 μm and 315–500 μm). | ||||
| 6. | Pipette 40 cm3 of the appropriate SI solution into each bottle (V = 0.04 L) slowly. | ||||
| 7. | Cap the bottles and shake for 5 s thoroughly, to ensure the system was mixed properly, before placing in an oven at a test temperature (95 °C) and atmospheric pressure. | ||||
| 8. | Check the bottle caps for tightness after 1 h and tighten if loose, to avoid evaporation. | ||||
| 9. | After 24 h in the oven, remove the test bottles and immediately filter through individual 0.22 μm membrane filters; keep the labeled mineral/precipitate on their filter papers and the separate supernatant solutions. | ||||
| 10. | Leave the filtered supernatant solution to cool to room temperature for approximately 24 h. | ||||
| 11. | Measure the post-test pH. | ||||
| 12. | Sample the filtered supernatant using a pipet and dilute the sample volume in a known matrix volume ready for analysis alongside the associated stock solutions by inductively coupled plasma-optical emission spectrometry (ICP-OES) for [DETPMP], [Ca2+], and [Mg2+]. Analyze the [SI] of the VS-Co samples by the wet chemical matrix-matched Hyamine technique instead of ICP-OES. (51) | ||||
| 13. | Perform ESEM/EDX analysis and PSA on the collected and dried solid phases (precipitate/mineral combined and separate) to analyze the morphology and particle size of the mineral-substrate grains and any bulk precipitate formed. | ||||
Figure 2
Figure 2. Scheme of static adsorption and compatibility experiment.
It should be mentioned that, in the environment in which the experiment was performed (our laboratory), the carbon dioxide concentration was negligible. So, there is no need to control the small amount of CO2. Moreover, the plastic bottles were capped tightly, so CO2 could not get out of the system. When the bottles were put in the oven, the caps were checked after an hour to ensure no evaporation (CO2 liberation) happens during the experiment. Li+ was also added as an inert element into the solution and [Li+] was analyzed before and after the static adsorption test. This is the way we trace the evaporation of solution (CO2 liberation) at high temperatures and consequently the error of our experiment.
In the bulk compatibility tests, no mineral was present, and all test and stock solutions were analyzed by ICP-OES to measure the difference in ionic compositions. Any difference in concentrations between the test and stock values were assumed to be related to pure precipitation at this stage (Π only). In the presence of mineral substrate, the apparent adsorption of SI retained by the mineral, Γapp (in mg SI/g substrate), was calculated using the following equation: (45)
where C0 and Cf are the initial and final SI concentrations, respectively, V is the volume of SI solution, and m is the mass of mineral substrate. In these experiments, the results were plotted as Γapp versus Cf. Note that apparent adsorption is used because both adsorption (Γ) and precipitation (Π) may be occurring simultaneously, and thus the apparent adsorption is a combination of both mechanisms (Γ/Π). It should be noticed that the adsorption is expressed as mg SI/g substrate here, as mentioned above. Because the surface area of the mineral substrate (i.e., in m2/g) in this reactive system is actually changing since there is some degree of preferential dissolution of the smaller fraction of the carbonate mineral which has the higher area/mass ratio. Moreover, the mass of substrate at all times is actually an absolute value, even in this chemically reacting system (SI/carbonate systems). (45) Finally, our mathematical model, on which the entire (Γ/Π) theory is based, (23,52−54) directly uses the mass/mass formulation; hence, the first part of the analysis if we expressed Γapp in mol/area or mg/area would be to convert to mass/mass.
(1)
2.2. Analysis Methods
2.2.1. Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES)
ICP-OES was used to analyze for the specific ions of interest (phosphorus, calcium, magnesium, and lithium) in the supernatant, before and after filtration, using a Thermofisher dual view iCAP 6500 system. (45)
2.2.2. Environmental Scanning Electron Microscopy–Energy Dispersive X-ray (ESEM-EDX)
ESEM-EDX analysis was used to examine the surface of the crushed calcite before and after the apparent adsorption experiments. This was performed to investigate the possible morphology of the precipitated complex in the presence of calcite substrate and, in particular, to establish if the precipitate was formed as a grain coating around the calcite particles or whether it formed independently as a bulk precipitate. Therefore, after filtration, all the filter papers containing calcite substrate and (in some cases) the precipitated complex for each of the SI concentrations tested were dried and examined by ESEM-EDX analysis. For this study, a Philips XL30 ESEM system, with an Oxford Instruments cryo-stage and an EDX detector, was used for the analysis. (34,45)
2.2.3. Particle Size Analysis (PSA)
Particle size distributions (PSDs) were measured for all precipitates using a Malvern Instruments MasterSizer for all precipitates that formed in the apparent adsorption experiments. The PSD for the SI-divalent cation precipitate (SI/M2+) (size fractions of 1 μm and larger) was obtained using a 45 mm lens (size range from 0.1 to 80 μm). PSA was further used to explain the apparent adsorption results by confirming the formation of the SI/M2+ complex in the mixtures. (46)
2.3. Materials
2.3.1. Scale Inhibitors
Two scale inhibitors were used in this work, which are (1) diethylene triamine penta (methylene phosphonic acid) or DETPMP, DETA-phosphonate, and (2) sulfonated polyacrylic acid copolymer or VS-Co. These SIs are commercial chemicals, which are commonly used in oilfield applications, and the structures of these SIs are presented in Figure 3. (45,55) DETPMP and VS-Co were supplied by Italmatch and ChampionX (previously Nalco Champion) companies, respectively. In the case of VS-Co, the chemical supplier did not provide us with the specifications of the inhibitors, including molecular weight and the percentage of sulfonation.
Figure 3
Figure 3. Specifications of the scale inhibitors (SI) used in this work. Reproduced with permission from ref (45). Copyright 2020 American Chemical Society.
2.3.2. Substrate
The substrate used was Moroccan calcite, which was sourced from the UK Geology Company (UKGE). This rock was crushed and sieved down to the desired size fractions (125–250 and 315–500 μm), before being washed with distilled water to remove any fines. Prior to use, the materials were allowed to air-dry. We have checked the effect of particle size (i.e., specific surface area) of the crushed carbonate, and results are not dependent on this, indicating that the effect is controlled by the extent of chemical reaction rather than surface effects (although the kinetics is a little faster for the smaller particle size). (18,32,45) ESEM/EDX analysis was used to characterize the morphology and elemental compositions of the pure calcite, (32,46) as shown in Figure 4 and Table 1. The elements detected by EDX analysis were calcium, oxygen, and carbon, confirming the composition of the substrates (three different parts of the examined surface were analyzed to make sure that the EDX results are precise and accurate).
Figure 4
Figure 4. Morphology of pure calcite on ESEM photographed sample.
Table 1. EDX Signals on the Pure Calcite from ESEM
| element | pure calcite (weight %) | pure calcite (atomic %) |
|---|---|---|
| C | 17 | 25 |
| O | 57 | 63 |
| Ca | 26 | 12 |
This carbonate rock was further characterized by dissolving them in 100 mL of 10% HCl solution, and the solutions were analyzed by ICP-OES to determine cation concentrations (Ca, Mg, and Fe); the results are presented in Table 2.
Table 2. Characterization of the Carbonate Substrates
| carbonate type | calcium (mole) | magnesium (mole) | iron (mole) | Mg/Ca ratio |
|---|---|---|---|---|
| Moroccan calcite | 9 × 10–6 | 3 × 10–9 | 2.5 × 10–8 | 3.3 × 10–4 |
For the Moroccan calcite studied, there was negligible magnesium impurity observed, and the chemical formula was confirmed as CaCO3.
2.3.3. Brine
The brine solution used was synthetic North Sea seawater (NSSW). This brine was made by dissolving the appropriate salts in distilled water as listed in Table 3. The brine solution was filtered through a 0.45 μm filter to remove any undissolved solids before use, in accordance with normal industry practice. 50 ppm lithium (Li+) was added as an inert tracer to determine whether any evaporation occurred during static adsorption and compatibility tests.
Table 3. Synthetic NSSW Composition
| ion | concentration (ppm) | salt used | mass of salt(g/L) |
|---|---|---|---|
| Na+ | 10 890 | NaCl | 24.08 |
| Ca2+ | 428 | CaCl2·6H2O | 2.34 |
| Mg2+ | 1368 | MgCl2·6H2O | 11.44 |
| K+ | 460 | KCl | 0.88 |
| SO42– | 2960 | Na2SO4 | 4.38 |
| Li+ | 50 | LiCl | 0.3055 |
| Cl– | 19 766 |
As shown in Table 3, Iron was not added into the NSSW water sample because iron is easily oxidized and is used up in the system instantly. In addition, silica was not also included in the synthetic NSSW. Because the aqueous fluid typically had less than 2 ppm, which would have no effect on the results. So, silica plays a negligible role in this system.
3. Coupled Adsorption/Precipitation Model
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A coupled adsorption/precipitation model reported by Kahrwad et al. (23) was used to predict the experimental results of coupled adsorption/precipitation (Γ/Π) processes. Kahrwad et al. (23) used this model for similar DETPMP Γ/Π processes but on different substrates: sand, clays, and siderite, which are much less chemically reactive than calcium carbonate.
As discussed, the apparent adsorption of SI (Γapp) retained by the mineral is described using eq 1 and it is shown schematically in Figure 5, where the precipitation is shown to occur by the formation of the calcium salt of the SI, that is, by precipitation of SI_Can. In general, the stoichiometry of this precipitation reaction is as follows:
where n Ca ions may bind to a single SI molecule. The solubility of this sparingly soluble salt would be described by an equilibrium solubility product, Ksp, of the form:
(2)
(3)
Figure 5
Figure 5. Schematic showing how both coupled adsorption and precipitation can occur showing how this could be interpreted as an “apparent adsorption”, Γap.
In fact, eq 3 is just a parametrized “solubility model”, which tries to capture the fact that the higher the [SI] or [Ca] then the more precipitate that is formed.
Some additional notation is introduced in Figure 5 as follows:
C1,0 and C1,f─initial (t = 0) and final equilibrium (t → ∞) of SI with the unit of molar concentration (M)
C2,0 and C2,f─initial (t = 0) and final equilibrium (t → ∞) of Ca with the unit of molar concentration (M)
Γ─the adsorption, which depends on C1,f, Γ = Γ(C1,f) (mg/g)
Π─is the precipitation process depending on both C1,f (SI concentration) and C2,f (Ca concentration) through Ksp as Ksp = (C1,f). (C2,f)n in this notation when the system is in equilibrium; units of Ksp → Mn+1
mp─the actual mass of precipitate that forms
According to the definition of the parameters, the coupled adsorption/precipitation model reported by Kahrwad et al. is as follows:
where, at equilibrium adsorption/precipitation, one must solve this equation for C1,fthat is, find the root of F(C1f) = 0. Note that the term 
describes precipitation, where n is the stoichiometry of Ca2+ ions involved in precipitation reaction (eq 2) or precipitation factor.
(4)
describes precipitation, where n is the stoichiometry of Ca2+ ions involved in precipitation reaction (eq 2) or precipitation factor.Note: The SI adsorption isotherm is based on Freundlich isotherm (the adsorbate (SI) forms a monomolecular layer on the surface of the adsorbent (calcite in this case)). Here, the Freundlich form is assumed, as follows:
where α and β are constants. In this work, these constants are determined based on the experimental results of SI–calcite system with 5 g of calcite, that is, a trial-and-error process for α and β was performed to achieve the optimal match with the experimental results. Once the best constants have been chosen, the adsorption isotherm could be predicted for other amounts of substrate, that is, in this work, the results of adsorption isotherm for the SI–calcite system with 10 g of calcite were predicted and compared with the experiments as reported in the next section.
(5)
4. Results and Discussion
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4.1. DETPMP–Calcite
4.1.1. Adsorption/Compatibility Test
The scale inhibitor DETPMP was used at initial concentrations of 50, 100, 500, 2000, and 4000 ppm for the compatibility and apparent adsorption experiments. Figure 6 shows the apparent adsorption of scale inhibitor, Γapp (mg SI/g rock), as a function of final SI concentration, Cf (ppm), for two different masses of calcite with size fractions of 125–250 and 315–500 μm in synthetic NSSW at pH0 4 at 95 °C.
Figure 6
Figure 6. Apparent adsorption (Γapp vs Cf,) for DETPMP onto 2 masses (m = 5 and 10 g) of calcite for two size fractions of calcite (315–500 μm and 125–250 μm) at pH0 4 and T = 95 °C. Solid lines are matched to calculate β and n in eqs 4 and 5. Dashed lines are predicted using the model. Inset: Pure adsorption region.
The regions of both pure adsorption (Γ) and coupled adsorption/precipitation (Γ/Π) are observed at lower and higher initial SI concentrations respectively as shown in Figure 6. Only pure adsorption (Γ) is seen for [SI] up to ≈100 ppm DETPMP, i.e., before the curves with different (m/V) start to deviate from each other due to coupled adsorption/precipitation occurring. (18,34) The pure adsorption region is shown in the inset of Figure 6 with much higher resolution. In this pure adsorption region, all curves almost overlap and locally plateau at a level of Γ ∼0.09–0.16 mg/g; this is a reasonable level if the mechanism is purely adsorption. However, above ca. 100 ppm of DETPMP, not only do the curves with different (m/V) diverge, but also, they lead to levels of apparent adsorption of Γapp ∼ 1–22 mg/g. Therefore, both the divergence of the Γapp vs Cf curves and the levels of “apparent” adsorption indicate that both pure adsorption (Γ) and precipitation (Π) mechanisms are involved above ca. 100 ppm of DETPMP, indicating coupled adsorption/precipitation. It is also noted that, within experimental accuracy, there was very little quantitative difference between the two size fractions of calcite 125–250 μm and 315–500 μm. That is, the coupled Γ/Π effect is driven by the DETPMP/calcite chemistry and, the particle size range does not affect the coupled Γ/Π results. In other words, the particle size does not affect the final (equilibrium) amount of apparent adsorption, although it has an impact on the kinetics of system (the smaller particles in the system, the quicker interaction they have with the scale inhibitors), and the SIs chemistry has governed the interaction of SI with calcite grains.
Figure 6 also shows that there was a reasonable match between experimental results and prediction using the model described in Section 3. As discussed, the data both for the pure adsorption and coupled Γ/Π regions for m = 5 g was used to tune the model to find α, β, and n which are 245, 0.85, 0.17 and 230, 0.82, 0.195 for the size fraction of 315–500 μm and 125–250 μm, respectively. Having these parameters, as shown in Figure 6, the results for the case with m = 10 g could be predicted without any additional parameters. As expected, for pure adsorption, the data for m = 5 and 10 g fall on the same adsorption isotherm, which is described here very well by the Freundlich form (Γ(C1f) = α (C1f)β). (23)
To support the results of static apparent adsorption/compatibility test in Figure 6, the results of pH and final [Ca2+] were investigated as shown in Figures 7 and 8, respectively. Changes in the final solution pH can be attributed to the loss of [Ca2+] and [Phosphorus] because of the precipitate formed. Figure 7 shows the pH changes versus final [DETPMP] for each of the points in Figure 6.
Figure 7
Figure 7. Comparison of pH trend for different masses of calcite (315–500 and 125–250 μm) versus final [DETPMP]
Figure 8
Figure 8. Normalized [Ca2+] (C/C0) versus final [DETPMP] for the size fractions of 315–500 and 125–250 μm.
As shown in Figure 7, no significant change in pH was observed in the compatibility test (the test without calcite). (18,45) Therefore, DETPMP could be considered as a fully compatible SI with NSSW in the solution without mineral and at pH0 4. However, when the calcite substrate was added into the solution, the pH increased from pH0 4 to around pH 8. This was attributed to the dissolution of calcite in the scale inhibitor solution and the consequent generation of in situ calcium. As the initial [SI] was increased, the in situ calcium generated will interact with the phosphonate groups in the DETPMP and a sparingly soluble Ca-DETPMP complex will be formed. This, in turn, will result in loss of calcium and phosphorus from the solution (by Ca-DETPMP precipitation) with a consequent decline in solution pH from pH ∼8 to pH ∼ 5. This reduction in pH starts just above 100 ppm is consistent with the onset of the coupled adsorption/precipitation region for both size fractions as shown in Figure 6.
Figure 8 shows the normalized [Ca2+] (relative to the initial value of [Ca2+] in NSSW which is 428 ppm) for both compatibility and adsorption tests in calcite for the two size fractions of 315–500 and 125–250 μm. As shown in Figure 8, no noticeable change in normalized [Ca2+] was observed for the compatibility test, implying no precipitation in the absence of calcite substrate. This particularly shows that DETPMP is compatible with NSSW at pH0 4. (18,45)Figure 8 shows that, in the presence of calcite substrate, the normalized [Ca2+] increases by 20% (Δ[Ca2+] ≈ 100 ppm) in which reaches a plateau in the adsorption/precipitation region. While the precipitation of the Ca2+-DETPMP complex occurs, an increased normalized [Ca2+] is observed due to calcite dissolution as shown in Figure 8, that is, the final effect is a net increase of Ca2+ in the solution. Similar to pH analysis, Figure 8 indicates analogous results for both size fractions of calcite. An interim conclusion from the apparent adsorption results (Γapp vs Cf) and the supporting [Ca2+] and the pH analysis is the calcite particle size has no effect and that the DETPMP–calcite interaction is governed by the chemistry.
4.1.2. ESEM/EDX Analysis for DETPMP–Calcite
ESEM/EDX analysis was used to examine the surface of the crushed calcite before and after SI treatment in all apparent adsorption experiments. (18,32,45) ESEM images for the 315–500 μm size fraction are presented in Figure 9 and the corresponding EDX analysis is presented in Table 4 (the ESEM/EDX analysis for the 125–250 μm size fraction is almost the same). The ESEM/EDX analysis was utilized to explore the nature of the SI–M2+ complex precipitated in the presence of calcite. In particular, this analysis is used to establish whether the SI–M2+ complex was formed as a grain coating around the calcite particles or whether it formed separately as a bulk precipitate. (18,32) Hence, after filtration, all the filter papers containing calcite grain and, in some cases, the precipitated complex for each of the SI concentrations tested were dried and examined by ESEM/EDX analysis.
Figure 9
Figure 9. Morphology of samples for pure calcite, 100, 500, and 2000 ppm DETPMP for 315–500 μm calcite from ESEM photographed samples.
Table 4. EDX Analysis of the Samples for Pure Calcitea
| calcite grains pure sample | calcite 100 ppm | calcite grains 500 ppm | bulk precipitate, 500 ppm | calcite grains 2000 ppm | bulk precipitate, 2000 ppm | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| element | % weight | % atomic | % weight | % atomic | % weight | % atomic | % weight | % atomic | % weight | % atomic | % weight | % atomic |
| C | 14 | 21 | 13 | 24 | 17 | 26 | 17 | 26 | 37 | 44 | ||
| Na | 1 | 2 | 3 | 2 | 3 | 2 | 3 | 2 | ||||
| Mg | 2 | 2 | 2 | 2 | 5 | 4 | ||||||
| P | 5 | 3 | 5 | 3 | 1 | 1 | 14 | 9 | ||||
| Cl | 1 | 2 | 6 | 3 | 6 | 3 | 6 | 3 | ||||
| Ca | 29 | 13 | 31 | 13 | 21 | 10 | 21 | 10 | 17 | 7 | 21 | 18 |
| O | 57 | 66 | 54 | 59 | 46 | 54 | 46 | 54 | 45 | 48 | 51 | 64 |
a
100, 500, and 2000 ppm DETPMP for 100–315 μm of calcite at pH0 = 4 and T = 95 °C.
As shown in Figure 9 and Table 4, for pure calcite, most elements detected by EDX analysis are calcium, oxygen, and carbon, indicating the substrate is mainly calcite. For the 100 ppm DETPMP case, which is in the pure adsorption region, there are no traces of phosphorus (P) on the calcite grains and no significant changes in the elements compared with pure calcite. The Na and Cl detected here have come from seawater deposited on the filter paper. Pieces of evidence form the results of Figure 9 and Table 4 confirm that phosphorus is clearly detected at a high level (∼14% by weight) in the finer precipitate which forms mainly in the bulk phase. However, there is a small but detectable amount of phosphorus (∼0.39% by weight) on the calcite grains themselves for the 2000 ppm DETPMP case (no P can be detected on the calcite at 500 ppm DETPMP). This lower amount is possibly some of the SI/Ca precipitate adhering to the calcite surface or is part of the adsorbed SI. As the concentration of DETPMP increases from 500 to 2000 ppm, the amount of phosphorus detected clearly increases. (33,34) No “surface coating” of the SI/Ca complex around calcite grains was observed in these experiments, even for the highest concentration of SI. Thus, we see no evidence for the hypothesis of “surface poisoning” by the Ca-DETPMP complex.
4.1.3. Particle Size Analysis for DETPMP–Calcite
Particle size distribution (PSD) of the SI/Ca2+ complex was measured using a 45 mm lens (to see small particles (from ∼1–20 μm) and the results are presented in Figure 10. The PSD results indicate the absence of any fine particles in the Blank and 100 ppm cases, as no fine particles (precipitate of SI with Ca2+) of this size are formed in the pure adsorption region. However, for the cases with higher DETPMP concentration (500 and 2000 ppm), where the system was in a region of coupled adsorption/precipitation, the peaks of PSD was observed between ∼1–10 μm. (31,51) Clearly, these populations of smaller particles are the SI/Ca precipitated material which forms as this finer material. These observations agree very well with the direct visual results observed in the ESEM (e.g., Figure 9) and confirm that both retention mechanisms (pure adsorption and precipitation) are occurring in the DETPMP/calcite system.
Figure 10
Figure 10. Particle size distribution for precipitate deposited on filter paper in different concentrations of DETPMP using 45 mm lens.
4.2. VS-Co–Calcite
4.2.1. Adsorption/Compatibility Test
Another set of static adsorption/compatibility test was carried out for VS-Co as a polymeric SI at the natural pH (no pH adjustment) and temperature of 95 °C, that is, the scale inhibitor was used at different concentration of 1000, 2500, 5000, and 10000 ppm. Figure 11 shows the “apparent adsorption” results (Γapp vs Cf) of VS-Co (mg SI/g rock) for two different masses of calcite with size fractions of 125–250 and 315–500 μm in synthetic brine solution (NSSW).
Figure 11
Figure 11. Apparent adsorption (Γapp vs Cf) for VS-Co onto 2 masses (m = 5 and 10 g) of calcite for two size fractions of calcite (315–500 μm and 125–250 μm) at natural pH and T = 95 °C. Solid lines are matched to calculate n, α, and β in eqs 1 and 2. Dashed lines are predicted using the model. Inset: Pure adsorption region.
In contrast to DETPMP, the results of apparent adsorption for VS-Co show an extensive region of pure adsorption (Γ only) up to the concentration of ∼3000 ppm for both size fractions. Similar to DETPMP, beyond the pure adsorption region, the apparent adsorption curves for VS-Co diverge ([VS-Co] > 3000 ppm), indicating coupled adsorption/precipitation (Γ/Π). (33) The pure adsorption region is much more significant than was observed for DETPMP, and this is clearly evidenced by both the clear shape of the adsorption isotherm (Γ (C)) and the reasonable level of adsorption (i.e., Γmax plateaus at a level of up to Γ ∼0.40–0.47 mg/g which is a very typical value for this SI). It should be noticed that the Freundlich isotherm does not have a plateau. This was referring to the apparent behavior of the experimental adsorption data. All that was meant was that it was showing adsorption type behavior rather that the rapidly rising characteristics of precipitation.
At higher concentrations of VS-Co (Final [SI] > 3000 ppm), there was clearly a coupled adsorption/precipitation region which was confirmed by the direct observation of a precipitate using ESEM analysis, discussed in the next section. Although precipitation does occur in the VS-Co/calcite system, it is much lower than in the DETPMP/calcite system (Γapp ∼ 1–4 mg/g for VS-Co and Γapp ∼ 4–20 mg/g for DETPMP). Therefore, these two SI–calcite systems both show qualitatively similar regions of pure adsorption (Γ) and coupled adsorption/precipitation (Γ/Π), however, the extent and importance of these two regions differ. (33) The effect of precipitation is expected to be much more important than adsorption for DETPMP (and other phosphonates) as discussed in the previous section. In contrast, the results for VS-Co indicate that although some precipitation does occur, adsorption is more important. As shown in Figure 11, the results of apparent adsorption for VS-Co for both calcite size fraction are quite similar qualitatively and almost quantitatively. In this respect, the results for VS-Co/calcite system are quite similar to those for the DETPMP/calcite system (i.e., identical quantitative results are observed for both size fractions). Conclusively, it confirms that particle size does not have any significant effect on the equilibrium apparent adsorption results.
Like DETPMP, the coupled adsorption-precipitation model was used to predict the results of VS-Co/calcite apparent adsorption experiment. The data, both for the pure adsorption and coupled Γ/Π regions in VS-Co/calcite system for m = 5 g, was used to tune the model to find α, β, and n, which are 680, 0.88, 0.01077 and 690, 0.86, 0.01077 for the size fractions of 315–500 and 125–250 μm, respectively. As shown in Figure 11, apparent adsorption could be well predicted (based on above coefficients) for the VS-Co/calcite systems with 10 g of calcite for both size fraction.
The prediction results of these two scale inhibitors (DETPMP and VS-Co) shows that the model for analyzing apparent adsorption experiments which includes both pure adsorption (Γ) and coupled adsorption/precipitation (Γ/Π) regions works reasonably well for SIs on carbonate (calcite) mineral substrates. Therefore, this model could predict the apparent adsorption for both DETPMP/calcite and the VS-CO/calcite systems, although the former is hugely dominated by precipitation (Π) and the latter is mostly dominated by pure adsorption (Γ).
Final pH values as a function of final concentration of VS-Co have also been measured which are shown in Figure 12. As shown in Figure 12, the blank sample (no scale inhibitor) has a pH value of 5.89 and it decreases to pH 4.69 at 10000 ppm of VS-Co SI. This reduction of pH is due to the acidic nature of VS-Co scale inhibitor, that is, the pH value of VS-Co decreases as [VS-Co] increases. So, the nature pH of solution means that the pH of solution has not been adjusted and it varies from 5.89 to 4.69 depending on the [VS-Co]. The results show that the final pH tends to flatten out around pH ≈ 8, which is due to the calcite. (33) The presence of calcite in the brine solution leads to being buffer of solution at final pH ≈ 8. Moreover, the VS-Co (initial pH ∼ natural pH (no pH adjustment)) like DETPMP (initial pH ∼ adjusted pH ∼ 4) is fully compatible with NSSW without mineral in the solution. So, we conclude these two types of scale inhibitors do not have incompatibility issue with NSSW. (31)
Figure 12
Figure 12. Comparison of pH trend for different masses of calcite (315–500 and 125–250 μm) versus final concentration of VS-Co.
Figure 13 shows the changes of normalized [Ca2+] (C/C0) in solution before and after the experiments for both adsorption and compatibility tests for both size fractions of calcite. As shown in Figure 13, the normalized [Ca2+] increased gradually up to ∼2.2 (normalized [Ca2+] in NSSW is 428 ppm) for the VS-Co/calcite system. This behavior contrasts with the DETPMP/calcite system, that is, the normalized [Ca2+] does not change significantly and remains at the level of ∼1.1–1.2 (Figure 8). This different behavior implies that for the VS-Co/calcite system, the increase of [VS-Co] does indeed leach more Ca2+ from the calcite into the solution, but this is not all precipitated, as is the case for the DETPMP/calcite system. It is well-known that the acidic (high dissociation constant (Ka) or low pKa) sulfonate groups in the VS-Co structure are very tolerant to high levels of divalent ions such as Ca2+. In contrast, the phosphonate groups in DETPMP bind very much more strongly to Ca2+ and the complex formed has a lower solubility. (33,56)
Figure 13
Figure 13. Normalized [Ca2+] (C/C0) vs final [VS-Co] for the size fractions of 315–500 and 125–250 μm.
4.2.2. ESEM/EDX Analysis for VS-Co–Calcite
Similar to DETPMP/calcite system, all solids which were collected from the static adsorption test for the VS-Co/calcite system have been examined using ESEM/EDX analysis. The ESEM results for the VS-Co/Calcite system with the size fraction of 315–500 μm for pure sample, 2500, 1000, and 10 000 ppm VS-Co are shown in Figure 14 and the corresponding EDX analysis is presented in Table 5.
Figure 14
Figure 14. Morphology of samples for (a) pure calcite, (b) 2500, (c) 1000, and (d)10 000 ppm VS-Co for 315–500 μm calcite from ESEM photographed samples.
Table 5. EDX Analysis of Pure Sample, 2500, 1000, and 10000 ppm VS-Co Samples for 315–500 μm Calcite at Natural pH, T = 95 °C from ESEM
| pure sample | calcite grains 2500 ppm | calcite grains 10 000 ppm | bulk precipitate 10 000 ppm | |||||
|---|---|---|---|---|---|---|---|---|
| element | % weight | % atomic | % weight | % atomic | % weight | % atomic | % weight | % atomic |
| N | 17 | 22 | ||||||
| C | 15 | 26 | 19 | 24 | 27 | 38 | ||
| Na | 1 | 1 | 1 | 1 | 4 | 3 | ||
| Mg | 1 | 1 | ||||||
| S | 1 | 1 | ||||||
| Cl | 1 | 1 | 7 | 4 | ||||
| K | 1 | 1 | ||||||
| Ca | 43 | 22 | 29 | 27 | 22 | 10 | 10 | 4 |
| O | 41 | 51 | 52 | 49 | 49 | 50 | 59 | 64 |
The results of pure calcite are similar to those reported in the previous section for DETPMP. The results in Table 5 also indicate that there was no S (Sulfur) signal in the pure calcite, that is, sulfur was not observed on the surface or precipitate. As discussed, the evidence shows coupled adsorption/precipitation, as shown in Figure 11. In this region, some small amount of sulfur on the calcite grain was detected, however, these results cannot specify certainly whether it is related to VS-Co, because there are two sources of sulfur, which are seawater (SO42–) and VS-Co.
4.2.3. Particle Size Analysis for VS-Co–Calcite
Particle size analysis (PSA) has been carried out for all the VS-Co apparent adsorption experiments using the smaller (45 mm) lens to detect smaller particles if they are present, as shown in Figure 15. Note that smaller particles are in the size range of 1–20 μm and are only detected for the highest concentration of VS-Co (10 000 ppm) case. For this case, these particles could be identified visually in the ESEM micrographs as shown in Figure 14d. No such particulates were observed in the pure adsorption region, as we expect.
Figure 15
Figure 15. Particle size analysis for 5 g of 125–250 μm calcite residue in different concentrations with 45 mm lens.
5. Analysis of Key Observations
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To understand the details and characteristics of the above results, it is necessary to investigate the various stages of the chemical processes which are involved. This can be approached by considering the SIs as weak polyacids of the form (HnA). (45,57) The dissociation and speciation of the SI are governed by pH, which the inhibitor determines, although an initial pH can be set experimentally, as was done here (pH0 4) for DETPMP. When the SI solution contacts the carbonate mineral substrate (calcite here), a chemical reaction occurs between them, generally dissolving/chelating some Ca2+ into the solution. The SI can then form an SI/Ca (and SI/Mg) complex that is sparingly soluble, and this may precipitate, which also affects the final pH of the solution. Thus, the SI/carbonate system comprises the three parts of the equilibrium system as follows: (45)
| (I) | Dissociation of scale inhibitor as a weak polyacid: SI dissociates like weak polyacid (HnA) to form dissociated species, such as Hn–1A– up to An– at very high pH values | ||||
| (II) | These dissociated SI species, which are very strong chelating agents, then bind with Ca2+ (and Mg2+) to form SI/Ca complexes that are barely soluble. The stoichiometry, shown by parameter n here, is the ratio of Ca ions to SI molecules. The chelation process of SI with divalent cations, mostly Ca2+, is described as (45) | ||||
| (III) | The above reactions must be coupled to the carbonate system. That is, the CO2/bicarbonate/carbonate coupled aqueous and the rock dissolution of the calcite as | ||||
A model describing this overall process is currently under development to perform this program, (58) although we could get a good match between experimental results and the model described above in section 3. This new model requires knowing the pH of the solution and quantities of Ca2+ generated by rock dissolution, for example, how much is involved in complexation (to form SI–Can) and how much remains in solution (as free Ca2+ or as soluble SI–Can complex). (46) With this understanding of the mechanisms involved in the carbonate/SI/Ca/Mg systems, an outline of the mechanistic schematic of the coupled processes (adsorption and precipitation) is presented for DETPMP and VS-Co.
5.1. Mechanistic Process in DETPMP/Carbonate System
As shown in Figure 16, at the first stage, the calcite substrate is dissolved in seawater and Ca2+ and CO32– are released out of the system. Thus, the pH of solution raised from the initial pH, in this DETPMP case pH0 4, to around 7. (46) In addition, Ca2+ is also increased. As it was mentioned, this carbonate system is governed by the carbonate equilibrium equations.
Figure 16
Figure 16. Schematic diagram of the mechanistic for calcite substrate, which is dissolved in seawater.
At the second stage, the adsorption of DETPMP on the calcite substrate occurs. Figure 17 illustrates the schematic diagram of the mechanistic for DETPMP adsorption on calcite. The SI (DETPMP in this case) dissociates as the pH increases which is due to calcite dissolution. DETPMP has five phosphonate functional groups which are susceptible to pH and they are easily deprotonated due to higher pKa (pKa ≈ 0.5–1.5). (59) When deprotonation (dissociation) occurs, the negatively charged species are produced and they adsorb on the positive charge surface of calcite through electrostatic interaction. This retention mechanism of SI happens at low [SI] ([DETPMP] ∼ 100 ppm). It is worth to mention that DETPMP also reacts with calcite substrate as it has acidic pH (≈4) and calcium and bicarbonate are leached out.
Figure 17
Figure 17. Schematic diagram of the mechanistic for DETPMP dissociation which results in adsorption of DETPMP on calcite substrate (at lower concentration, for example, [DETPMP] < 100 ppm) because of the increasing pH in seawater.
At higher concentration of DETPMP ([DETPMP] > 100 ppm), Ca2+ from solution is chelated by DETPMP and the SI/Ca complex precipitates out, that is, in other words, Ca2+ binds with dissociated DETPMP. The schematic diagram of the mechanistic for this process is shown in Figure 18. As Ca2+ and DETPMP are eliminated from the solution, the final pH of solution decreases, as shown in Figure 7. It should be noticed that Mg2+ may be chelated by DETPMP but the solubility product (Ksp) of DETMPM–Mgn is higher (more soluble) than that of DETPMP–Can. (60)
Figure 18
Figure 18. Schematic diagram of the mechanistic for DETPMP dissociation which results in adsorption/precipitation of DETPMP on calcite substrate (at higher concentration, e.g., [DETPMP] > 100 ppm) in seawater.
5.2. Mechanistic Process in VS-Co/Carbonate System
In VS-Co/carbonate system, like the DETPMP/carbonate system, calcite is dissolved in NSSW and calcium concentration and pH of the solution is increased due to carbonate release as shown in Figure 16 (the first stage in carbonate equilibrium equations).
In the presence of VS-Co, the SI dissociates and the negatively charged species is generated. The VS-Co has been synthesized from a 50/50% mix of vinyl sulfonate and acrylic acid monomers. Sulfonated polymers, for example, VS-Co, are least affected by changing of pH because an extremely low pH (e.g., pH < 1) is required to associate the highly acidic sulfonate functional groups. So, the VS-Co has a higher tolerance to chelate Ca2+ from solution (lower stability constants between SO3H group and Ca2+ and Mg2+). (56) However, it has also a carboxylic acid functional group which pH has much more effect on its speciation than that of the sulfonic acid functional group. So, carboxylic acid functional group dissociates, and the negative charge species is generated. (61) As a result of this negative charge species, electrostatic attraction causes the physical adsorption of VS-Co on the calcite substrate. This mechanistic of VS-Co dissociation and adsorption on calcite substrate is illustrated in Figure 19.
Figure 19
Figure 19. Schematic diagram of the mechanistic for VS-Co dissociation which results in adsorption of VS-Co on calcite substrate (at lower concentration, e.g., [VS-Co] < 3000 ppm) in seawater.
As the concentration of VS-Co increases, the dissociated R-COO– group chelates Calcium from the solution and the precipitate of VS-Co/Ca2+ forms. This Schematic diagram of the mechanistic for VS-Co precipitation is shown in Figure 20. It should be mentioned that VS-Co forms a polyanionic species after it dissociates as it is a polymeric scale inhibitor. Thus, it can adsorb on the positive surface charge calcite much better than DETPMP. This claim is confirmed by the apparent adsorption results presented in Figures 6 and 11, that is, dominant retention mechanism for VS-Co is pure adsorption (Γ), whereas for DETPMP is precipitation (Π), although both (Γ/Π) mechanisms were observed for both SIs.
Figure 20
Figure 20. Schematic diagram of the mechanistic for VS-Co dissociation which results in adsorption/precipitation of VS-Co on calcite substrate (at higher concentration, e.g., [VS-Co] > 3000 ppm) in seawater.
To sum up, we can point out that the change of the Gibbs free energy from the metastable condition to the stable (equilibrium) condition is defined as the thermodynamic driving force, that is, the system is prone to go to the state with the minimum Gibbs free energy. In terms of chemical potential, which is defined as molar Gibbs free energy (Gibbs free energy per mole of substance), a difference in chemical potential between two conditions is also defined as driving force. In the scale inhibitor retention processes (pure adsorption and precipitation) on the rock surface, (62) those inhibitors (DETPMP and VS-Co) have different chemistries and hence different adsorption behavior on the reservoir rocks. As mentioned above, phosphonate functional groups in DETPMP SI are susceptible to pH and they are easily deprotonated due to higher pKa. When deprotonation (dissociation) occurs, the negatively charged species are produced and they adsorb on the positive charge surface of calcite through electrostatic interaction. But this pure adsorption region is negligible somehow in the DETPMP/calcite system, as DETPMP actively reacts with calcite substrate and easily chelate Ca2+ in situ produced through rock dissolution. While, in the VS-Co/calcite system, sulfonated functional groups are least affected by changing of pH because of an extremely low pH (e.g., pH < 1). So, the VS-Co has a higher tolerance to chelate Ca2+ from solution (lower stability constants between SO3H group and Ca2+ and Mg2+). Thus, the pure adsorption region is more extended to higher [VS-Co] in comparison with [DETPMP]. It confirms that the adsorption driving force in VS-Co (greater difference in chemical potential) is higher than in DETPMP.
6. Summary and Conclusions
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The “apparent adsorption” behavior (Γapp vs Cf) of two common commercially available scale inhibitors (SI = DETPMP and VS-Co) on the carbonate mineral substrate, calcite, has been studied. This extends earlier work by including calcium carbonate (calcite) mineral substrate which is much more chemically reactive than sandstone minerals which we have studied in previous work (e.g., quartz, siderite, and clays). (23,33) A systematic study has been carried out of the effects of particle size of the calcite to test between two possible effects of the reaction of the SI with the calcite surface, namely, does the interaction occurs by (i) forming a coating on the calcite grain which “poisons” the continuing reaction or (ii) is it simple dominated by the bulk chemistry. In addition to the direct measurement of the (Γapp vs Cf) curves, ancillary measurement of final pH and solution [Ca2+] are also presented, along with corresponding detailed ESEM/EDX and particle size analysis (PSA) of the calcite/precipitated complex.
The specific conclusions from this work are as follows:
| 1. | For the DETPMP/calcite system, a domain of pure adsorption (Γ) is observed at lower SI concentration of [DETPMP] ≤ 100 ppm, as well a much more extensive region of coupled adsorption/precipitation (Γ/Π) behavior at [DETPMP] > 100 ppm. Qualitatively similar regions (i.e., pure Γ and coupled Γ/Π) were found for the VS-Co/calcite system, but in this case, the pure adsorption mechanism dominated up to [VS-CO] ≈ 2000 ppm, and only above this did some smaller amount of precipitate appear. For both SI/calcite systems, the calcite substrate is much more reactive than say quartz or clays since much more Ca2+ is leached into solution by the scale inhibitor. These differences between DETPMP and VS-Co in their behavior with calcite are due to the different SI–Ca binding strengths of the different functional groups present in each of these SIs. | ||||
| 2. | When different particle size ranges of calcite were used (315–500 and 125–250 μm in this work) in the apparent adsorption experiments for each SI (DETPMP and VS-Co), the overall behavior for each SI was broadly the same. That is, there was no strong effect of particle size and the Γapp versus Cf plots were very similar. The Γapp vs Cf plots for VS-Co were rather more closely reproduced quantitatively than those of DETPMP probably because the latter system was much more reactive and so was a little more difficult experimentally to reproduce exactly. This indicates that it is the fundamental SI–calcite chemistry that governs the Γapp versus Cf behavior (i.e., the regions of pure Γ and coupled Γ/Π) and not a surface deposition reaction (see 3 below). | ||||
| 3. | The experimental finding that the particle size was not of major importance in governing the Γapp versus Cf behavior, indicated that a possible poisoning reaction was not occurring at the calcite grain surface. This was further confirmed experimentally by carrying out ESEM/EDX analysis along with particle size analysis (PSA) of the calcite and the SI/Ca complex precipitates. No significant surface precipitation/coating of the SI/Ca complex on the calcite was observed by ESEM. Instead, a clear SI/Ca complex could be observed in ESEM for all DETPMP cases for [DETPMP] ≥ 500 ppm; this was shown by EDX to contain a significant amount of phosphorus (P) and Ca and particle size analysis showed that it consisted of a much finer particulate precipitate with size ∼1–20 μm. Likewise, a precipitate of VS-Co/Ca was also observed but only for high concentrations of [VS-Co] ≈ 10 000 ppm in which sulfur (S) was detected, although this S could be from the seawater (sulfate) or the sulfonate groups in the VS-Co polymer. We note that no finer precipitate was observed for either SI (DETPMP or VS-Co) in the pure adsorption region of the Γapp versus Cf curves. | ||||
| 4. | All of the Γapp versus Cf, experimental results were modeled using a model developed and published some time ago. (21) Apparent adsorption plots were constructed for various values of (m/V) ratio; m = mass of calcite substrate and V = scale inhibitor solution fluid volume. If these plots coincide for different (m/V) ratios over a range of final SI concentration values, then this indicates pure adsorption (Γ). Alternatively, if the Γapp curves diverge for different (m/V) ratios, then this shows that coupled adsorption/precipitation (Γ/Π) is occurring. The procedure in applying this model involves matching the Γapp versus Cf curve for a given (m/V) value (the m = 5 g case in this work) and then predicting the results for the other (m/V) ration (m = 10 g here). If both the match and prediction agree well with the experimental data, then our analysis of the retention mechanism (pure Γ, or coupled Γ/Π) is certainly correct both qualitatively and quantitatively. Very good agreement between the model and the experimental results was observed for both the DETPMP/calcite and the VS-Co/calcite systems. Thus, the model can capture the main features of coupled adsorption/precipitation in a reactive system such as in the SI/calcite cases for both DETPMP and VS-Co. | ||||
Author Information
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- Khosro Jarrahian - Flow Assurance and Scale Team (FAST), Institute of GeoEnergy Engineering (IGE), Heriot-Watt University, Edinburgh, EH14 4AS, U.K.;
https://orcid.org/0000-0001-7933-7607;
- Morteza Aminnaji - Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, M1 3AL, U.K.;https://orcid.org/0000-0002-5837-1336
Acknowledgments
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The following are thanked for their support of the FAST 6 Joint Industry Project at Heriot-Watt University: Halliburton Multi-Chem, Nalco Champion, Petronas, Repsol Sinopec, Schlumberger MI Swaco, Shell, Statoil, Total, and Wintershall. We also appreciate the Institute of GeoEnergy Engineering, Heriot-Watt University for support with the ESEM/EDX facility, and our colleague Wendy McEwan in the FAST Analytical Team at Heriot-Watt University for conducting the ICP-OES analysis. Finally, Italmatch and Nalco Champion Companies are gratefully acknowledged for providing the DETPMP and VS-Co scale inhibitors, respectively.
References
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This article references 62 other publications.
- 1Kelland, M. A. Effect of Various Cations on the Formation of Calcium Carbonate and Barium Sulfate Scale with and without Scale Inhibitors. Ind. Eng. Chem. Res. 2011, 50 (9), 5852– 5861, DOI: 10.1021/ie2003494Google Scholar1https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXkt1Cqu7s%253D&md5=63ad2599af88ff9907a237237141dd29Effect of Various Cations on the Formation of Calcium Carbonate and Barium Sulfate Scale with and without Scale InhibitorsKelland, Malcolm A.Industrial & Engineering Chemistry Research (2011), 50 (9), 5852-5861CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)High pressure dynamic tube blocking tests have been conducted to det. the effect of iron (divalent and trivalent), calcium, magnesium, and sodium ions on the formation of calcium carbonate and barium sulfate scale with and without added scale inhibitors. Scale inhibitors were chosen to represent the three main functional groups used in com. oilfield scale inhibitors: the phosphonate group (found in sodium diethylenetriaminepentaphosphonate), the carboxylate group (in sodium polyaspartate), and the sulfonate group (in sodium polyvinysulfonate). A fourth proprietary inhibitor with phosphonate and carboxylate groups was also used in some studies.
- 2Maffra, D. A.; Freitas, T. C.; da Cruz, G. F.; de Siqueira, F. D.; do Rosário, F. F. Evaluation of Barium Sulfate Scale Inhibition Using Relative Permeability Modifier Polymers as Adsorption Enhancer for Mature Offshore Well Treatments in Campos Basin, Brazil. Ind. Eng. Chem. Res. 2018, 57 (34), 11493– 11504, DOI: 10.1021/acs.iecr.8b01828Google Scholar2https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhsVejtr7O&md5=01950cd7a6f05a2e59725ee2eb563c48Evaluation of Barium Sulfate Scale Inhibition Using Relative Permeability Modifier Polymers as Adsorption Enhancer for Mature Offshore Well Treatments in Campos Basin, BrazilMaffra, Daniel A.; Freitas, Tiago C.; da Cruz, Georgiana F.; de Siqueira, Fernando D.; do Rosario, Francisca F.Industrial & Engineering Chemistry Research (2018), 57 (34), 11493-11504CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)In many mature offshore fields, high water cuts and potential scale deposition are some of the toughest challenges operators need to face. Two common practices used to deal with these challenges are relative permeability modifiers (RPM) polymer injection and scale inhibitor squeeze treatments. Even though many fields face these two challenges simultaneously, little is known about concomitant application of these treatments. In this paper, the effect of applying RPM polymers prior to inhibitor squeeze in the effectiveness of the last treatment is evaluated for sandstone rocks of Campos Basin, Brazil. Sequential lab. injections in Campos Basin rocks of com. cationic and anionic polyacrylamide and polyaluminum chloride (PAC) as crosslinking agent were employed prior to the injection of a com. organophosphonic acid type inhibitor for barium sulfate scale. It was found that the polymers employed are capable of reducing the permeability of porous media to water and increasing the retention time of the scale inhibitor simultaneously. The tests also indicated that the inhibitor's longer retention time is assocd. with the interaction with an outer cationic layer of the crosslinking agent. The adsorption isotherms were calcd. and compared with Langmuir, Freundlich, Sips, and Toth models, the last two being the most accurate in representing the adsorption system for these tests.
- 3He, S.; Kan, A. T.; Tomson, M. B. Mathematical Inhibitor Model for Barium Sulfate Scale Control. Langmuir 1996, 12 (7), 1901– 1905, DOI: 10.1021/la950876xGoogle Scholar3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28XhsFCjsLg%253D&md5=8e7d65bece08519c2f5e63955d47a65aMathematical Inhibitor Model for Barium Sulfate Scale ControlHe, Shiliang; Kan, Amy T.; Tomson, Mason B.Langmuir (1996), 12 (7), 1901-5CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)A semiempirical math. model has been developed to predict inhibitor efficiency for barium sulfate scale control in industrial processes. This model can be used for selecting effective inhibitors and detg. the minimal effective concn. needed for a given system. The model incorporates exptl. data of the nucleation and inhibition kinetics. Specifically, the induction period in the presence and absence of scale inhibitors has been measured exptl. and inputted into the model: Cinh = (1/b) log[tinh/t0], where Cinh is the inhibitor concn., tinh is the inhibition time (e.g., 20 min), t0 is the nucleation induction period of the scaling mineral crystal, and b is the inhibitor efficiency. The inhibition kinetics of barium sulfate nucleation with bis(hexamethylene)triaminepenta(methylenephosphonic acid) (BHMTPMP) and several other polyphosphonate and polyacrylate inhibitors have been measured. Many factors which are important to nucleation and inhibition kinetics, such as the degree of supersatn., temp., and soln. pH, have been included in the inhibitor model. The model prediction for barium sulfate scale control was in good agreement with lab. observations and field experience.
- 4Mady, M. F.; Rehman, A.; Kelland, M. A. Synthesis and Study of Modified Polyaspartic Acid Coupled Phosphonate and Sulfonate Moieties As Green Oilfield Scale Inhibitors. Ind. Eng. Chem. Res. 2021, 60, 8331, DOI: 10.1021/acs.iecr.1c01473Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXht1aktb7I&md5=c67b6758f07156be25669b521120b0cdSynthesis and study of modified polyaspartic acid coupled phosphonate and sulfonate moieties as green oilfield scale inhibitorsMady, Mohamed F.; Rehman, Abdur; Kelland, Malcolm A.Industrial & Engineering Chemistry Research (2021), 60 (23), 8331-8339CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)The petroleum industry has strived for several years to explore environmentally friendly scale inhibitors with no acute environmental impact. Well-known industrial biodegradable polyaspartic acid is widely used as a potent scale inhibitor (SI) against various inorg. scales in industrial circulating cooling water and topside petroleum applications. However, polyaspartic acid showed weak thermal stability at the petroleum reservoir temps. Here, we attempt to develop a new class of polyaspartic acid for squeeze treatment applications under harsh conditions. In this project, a series of modified polyaspartic acid, including pendant anionic functional moieties (phosphonate and sulfonate) were synthesized and investigated as new SIs to inhibit the calcium carbonate (calcite, CaCO3) and barium sulfate (barite, BaSO4) scales under oilfield conditions. These classes were synthesized via aminolysis of polysuccinimide with nucleophilic amine reagents under alk. conditions. The products are polyaspartic acid-capped aminomethylene phosphonic acid (SI-2), polyaspartic acid-capped bisphosphonic acid (SI-3), polyaspartic acid-capped aminomethanesulfonic acid (SI-4), and polyaspartic acid-capped aminoethanesulfonic acid (SI-5), as well as inhouse synthesized polyaspartic acid (SI-1). The scale inhibition activities of these compds. against carbonate and sulfate scales were detd. using the dynamic scale loop test at 100°C and 80 bar. Furthermore, the long-term thermal aging and calcium tolerance expts. were also investigated. It was found that polyaspartic-acid-capped aminomethylene phosphonic acid (SI-2) gave outstanding calcite scale inhibition performance and showed excellent thermal stability at 130°C for 7 days compared to SI-1 and other modified SIs (SI-3-SI-5). This phosphonated polymer also exhibited superior calcium tolerance performance with Ca2+ ions up to 100 ppm, and moderate performance in the range of 1000-10 000 ppm calcium ions. This project highlights the success of designing and developing a new environmentally friendly calcite SI-based polyaspartic acid under harsh oilfield conditions.
- 5Dietzsch, M.; Barz, M.; Schüler, T.; Klassen, S.; Schreiber, M.; Susewind, M.; Loges, N.; Lang, M.; Hellmann, N.; Fritz, M.; Fischer, K.; Theato, P.; Kühnle, A.; Schmidt, M.; Zentel, R.; Tremel, W. PAA-PAMPS Copolymers as an Efficient Tool to Control CaCO3 Scale Formation. Langmuir 2013, 29 (9), 3080– 3088, DOI: 10.1021/la4000044Google Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXitFajsbo%253D&md5=fb1893a70f6ffbed2b41d6bb68ab297aPAA-PAMPS Copolymers as an Efficient Tool to Control CaCO3 Scale FormationDietzsch, Michael; Barz, Matthias; Schueler, Timo; Klassen, Stefanie; Schreiber, Martin; Susewind, Moritz; Loges, Niklas; Lang, Michael; Hellmann, Nadja; Fritz, Monika; Fischer, Karl; Theato, Patrick; Kuehnle, Angelika; Schmidt, Manfred; Zentel, Rudolf; Tremel, WolfgangLangmuir (2013), 29 (9), 3080-3088CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Scale formation, the deposition of certain minerals such as CaCO3, MgCO3, and CaSO4·2H2O in industrial facilities and household devices, leads to reduced efficiency or severe damage. Therefore, incrustation is a major problem in everyday life. In recent years, double hydrophilic block copolymers (DHBCs) have been the focus of interest in academia with regard to their antiscaling potential. In this work, we synthesized well-defined blocklike PAA-PAMPS copolymers consisting of acrylic acid (AA) and 2-acrylamido-2-methyl-propane sulfonate (AMPS) units in a one-step reaction by RAFT polymn. The derived copolymers had dispersities of 1.3 and below. The copolymers have then been investigated in detail regarding their impact on the different stages of the crystn. process of CaCO3. Ca2+ complexation, the first step of a pptn. process, and polyelectrolyte stability in aq. soln. have been investigated by potentiometric measurements, isothermal titrn. calorimetry (ITC), and dynamic light scattering (DLS). A weak Ca2+ induced copolymer aggregation without concomitant pptn. was obsd. Nucleation, early particle growth, and colloidal stability have been monitored in situ with DLS. The copolymers retard or even completely suppress nucleation, most probably by complexation of soln. aggregates. In addn., they stabilize existing CaCO3 particles in the nanometer regime. In situ AFM was used as a tool to verify the coordination of the copolymer to the calcite (104) crystal surface and to est. its potential as a growth inhibitor in a supersatd. CaCO3 environment. All investigated copolymers instantly stopped further crystal growth. The carboxylate richest copolymer as the most promising antiscaling candidate proved its enormous potential in scale inhibition as well in an industrial-filming test (Fresenius std. method).
- 6Mirzaalian Dastjerdi, A.; Kargozarfard, Z.; Najafi, B.; Taghikhani, V.; Ayatollahi, S. A Microscopic Insight into Kinetics of Inorganic Scale Deposition during Smart Water Injection Using Dynamic Quartz Crystal Microbalance and Molecular Dynamics Simulation. Ind. Eng. Chem. Res. 2020, 59, 609, DOI: 10.1021/acs.iecr.9b05236Google Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisVektrjP&md5=9a2cfc2d6055a4ba137c6f13cd33cba2Microscopic Insight into Kinetics of Inorganic Scale Deposition during Smart Water Injection Using Dynamic Quartz Crystal Microbalance and Molecular Dynamics SimulationMirzaalian Dastjerdi, Ali; Kargozarfard, Zahra; Najafi, Bita; Taghikhani, Vahid; Ayatollahi, ShahabIndustrial & Engineering Chemistry Research (2020), 59 (2), 609-619CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Inorg. scale deposition has been found to affect many industrial processes, including water injection into the oil reservoirs. The incompatibility of high sulfate ion content of seawater with formation water contg. calcium ions results in formation damage and prodn. decline. In this study, several simultaneous techniques are utilized for qual. and quant. analyses of calcium sulfate scale to get more insight into the formation damage during smart water flooding at micro and nanoscales. In the exptl. section, calcium sulfate deposition due to the mixing of the formation water and seawater samples was investigated using the dynamic quartz crystal microbalance technique. The effect of sulfate and magnesium ions existing in the seawater on the amt. of calcium sulfate deposition was studied, individually. The results showed that the sulfate concn. of seawater could significantly change the mass deposition in a specific range. Also, at an optimal concn. of the magnesium ions, the total amt. of calcium sulfate deposition decreased by 60%. However, magnesium ions could decrease the time of the initial stage of deposition significantly. The results revealed the amt. of deposition and the time of initial stage beyond 5 times diln. of seawater are not noticeable. In addn., the linear slope of the second stage of deposition for the mixt. of formation water and 5-fold dild. seawater decreased by 92% compared to the original seawater. To verify the results for the magnesium effect, the mol. dynamics simulation method was used to compare the simulation results with the exptl. data. Likewise, the results obtained from the simulation model showed that at an optimal concn. of the magnesium ions in the seawater, the amt. of calcium sulfate deposition was noticeably decreased.
- 7Chao, Y.; Horner, O.; Vallée, P.; Meneau, F.; Alos-Ramos, O.; Hui, F.; Turmine, M.; Perrot, H.; Lédion, J. In Situ Probing Calcium Carbonate Formation by Combining Fast Controlled Precipitation Method and Small-Angle X-Ray Scattering. Langmuir 2014, 30 (12), 3303– 3309, DOI: 10.1021/la500202gGoogle Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXjtV2qtbg%253D&md5=8e45e03db990c59a6b578f409e7bfc76In Situ Probing Calcium Carbonate Formation by Combining Fast Controlled Precipitation Method and Small-Angle X-ray ScatteringChao, Yanjia; Horner, Olivier; Vallee, Philippe; Meneau, Florian; Alos-Ramos, Olga; Hui, Franck; Turmine, Mireille; Perrot, Hubert; Ledion, JeanLangmuir (2014), 30 (12), 3303-3309CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)The initial stage of calcium carbonate nucleation and growth, found usually in "natural" pptn. conditions, is still not well understood. The calcium carbonate formation for moderate supersatn. level could be achieved by an original method called the fast controlled pptn. (FCP) method. FCP was coupled with SAXS (small-angle X-ray scattering) measurements to get insight into the nucleation and growth mechanisms of calcium carbonate particles in Ca(HCO3)2 aq. solns. Two size distributions of particles were obsd. The particle size evolutions of these two distributions were obtained by analyzing the SAXS data. A nice agreement was obtained between the total vol. fractions of CaCO3 obtained by SAXS anal. and by pH-resistivity curve modeling (from FCP tests).
- 8Hasson, D.; Shemer, H.; Sher, A. State of the Art of Friendly “Green” Scale Control Inhibitors: A Review Article. Ind. Eng. Chem. Res. 2011, 50 (12), 7601– 7607, DOI: 10.1021/ie200370vGoogle Scholar8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXmsVWls7s%253D&md5=cfa952d7743338a6b1f94beb4bd86c94State of the Art of Friendly "Green" Scale Control Inhibitors: A Review ArticleHasson, David; Shemer, Hilla; Sher, AlexanderIndustrial & Engineering Chemistry Research (2011), 50 (12), 7601-7607CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)A review is given. Scale deposition is a difficulty encountered with water contg. ions of sparingly sol. salts. A widely used technique for controlling scale deposition is by dosage of an antiscalant. Large quantities of polymeric scale inhibitors are used for scale control in cooling water systems, water desalination processes, and oil field operations. Like most conventional polymers, scale inhibitors are built for long existence and persist for many years after their disposal. Increasing environmental concern and discharge limitations have caused scale-inhibitor chem. to move toward green antiscalants that readily biodegrade, have low mobility for min. environmental impact, and are cost-effective. This review summarizes efforts to develop cost-effective ecol. benign scale inhibitors. Currently, the most promising green scale inhibitors are based on poly(aspartic acid). However, field operation data are very limited, and widespread use of poly(aspartic acid) scale inhibitors awaits field operation experience.
- 9Baraka-Lokmane, S.; Sorbie, K. S. Effect of PH and Scale Inhibitor Concentration on Phosphonate–Carbonate Interaction. J. Pet. Sci. Eng. 2010, 70 (1–2), 10– 27, DOI: 10.1016/j.petrol.2009.05.002Google Scholar9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsF2isrzJ&md5=ccef234bfbffbcf7d5218ca9374cb315Effect of pH and scale inhibitor concentration on phosphonate-carbonate interactionBaraka-Lokmane, S.; Sorbie, K. S.Journal of Petroleum Science & Engineering (2010), 70 (1-2), 10-27CODEN: JPSEE6; ISSN:0920-4105. (Elsevier B.V.)In this paper, we present results from five corefloods (RC1 to RC5) from the Jurassic Portlandian limestone (Φ ∼ 19.80% and k = 606 mD) using 5000 ppm, 10,000 ppm, 25,000 ppm and 27,000 ppm of partly neutralized Diethylenetriamine pentamethylenephosphoric acid (DETPMP) at pH 4 and 2. The purpose of this study was to study the effect of inhibitor concn. and pH on the inhibitor adsorption and on the evolution of the inhibitor and cation (calcium and magnesium) return concns. These corefloods were performed using long cores (12 in.), which were treated with just 0.5 pore vol. (PV) of inhibitor. Another purpose was to study the transport and inhibitor/carbonate rock interactions when less than 1 PV of inhibitor soln. is injected. This allows for consumption of the inhibitor during propagation and return, rather than satg. the core with many PV to full adsorptive capacity of the inhibitor/rock system. This study showed that the higher the concn. of SI and lower the pH, the more calcium dissoln. is obsd. (from the [Ca2+] effluents). In all treatments there is a decrease in the [Mg2+] effluent corresponding directly to the increase in calcium. The effluent cation results in the long corefloods which strongly support the view that both magnesium and calcium are binding quite strongly to the DETPMP scale inhibitor. These observations lead us to a no. of conclusions on the factors that must be included in a full carbonate model. In particular, our exptl. results, along with some simple modeling, greatly clarify the role of both calcium and magnesium in the mechanism of the scale inhibitor retention in carbonate systems.
- 10Khormali, A.; Petrakov, D. G.; Nazari Moghaddam, R. Study of Adsorption/Desorption Properties of a New Scale Inhibitor Package to Prevent Calcium Carbonate Formation during Water Injection in Oil Reservoirs. J. Pet. Sci. Eng. 2017, 153, 257– 267, DOI: 10.1016/j.petrol.2017.04.008Google Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXlvFynuro%253D&md5=f16d6dc6430615ef37974770393424a6Study of adsorption/desorption properties of a new scale inhibitor package to prevent calcium carbonate formation during water injection in oil reservoirsKhormali, Azizollah; Petrakov, Dmitry G.; Nazari Moghaddam, RasoulJournal of Petroleum Science & Engineering (2017), 153 (), 257-267CODEN: JPSEE6; ISSN:0920-4105. (Elsevier B.V.)Injection of an aq. soln. of scale inhibitor during the water flooding is the primary method to prevent inorg. salt formation. Adsorption/desorption abilities of scale inhibitors are key factors that influence the success of the scale inhibitor squeeze treatments. In this work, the performance of a new developed scale inhibitor has been evaluated to prevent calcium carbonate pptn. under static and dynamic conditions. Prior to any core flooding expts., satn. index of calcium carbonate and the amt. of its pptn. were studied at different mixing ratios of the synthetic injection and formation waters at different temps. Then, effectiveness of the scale inhibitor package and its min. concn. were detd. During the core flooding expts., adsorption characteristics of the scale inhibitor package were investigated using carbonate, quartz sand and quartz glass core samples. For each test, the inhibitor soln. was injected into the core samples and its concn. was measured before and after passing through the core samples. Moreover, specific adsorption of the scale inhibitor package was detd. at different injection rates. For the carbonate samples, adsorption equil. of the scale inhibitor package occurred in the lower pore vols. injected. Furthermore, improvement in the adsorption ability of the scale inhibitor package occurred due to the presence of various chem. reagents in the compn. of the scale inhibitor package. In this study, desorption process has been also studied on carbonate rocks. The results showed that the best performance of desorption process was obtained when the concn. of hydrochloric acid was 10% in the developed scale inhibitor package. In addn., redn. in dynamic viscosity of oil was obsd. in the presence of the scale inhibitor package. Interfacial tension on the boundary of oil and the aq. soln. of the scale inhibitor package was significantly reduced by an increase in the concns. of polyethylene polyamine-N-methylphosphonic acid (PPNMP) and hydrochloric acid as the components of the inhibitor package.
- 11Liu, C.; Zeng, X.; Yan, C.; Zhou, C.; Li, M.; Wang, Z. Effects of Solid Precipitation and Surface Corrosion on the Adhesion Strengths of Sintered Hydrate Deposits on Pipe Walls. Langmuir 2020, 36, 15343, DOI: 10.1021/acs.langmuir.0c02818Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisFCrtLzJ&md5=34e32677e513ba3e2cbefcdd8b4ea9ccEffects of Solid Precipitation and Surface Corrosion on the Adhesion Strengths of Sintered Hydrate Deposits on Pipe WallsLiu, Chenwei; Zeng, Xu; Yan, Ci; Zhou, Chenru; Li, Mingzhong; Wang, ZhiyuanLangmuir (2020), 36 (50), 15343-15351CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)A hydrate directly growing and sintering on a pipe wall is an important hydrate deposition case that has been relatively unexplored. In the present study, the adhesion strengths of a sintered cyclopentane (CyC5) hydrate deposit under different solid pptn. and surface corrosion conditions were measured and discussed. It was found that the hydrate adhesion strengths increased by 1.2-1.5x when the soaking time of the carbon steel substrate in a 5 wt % NaCl soln. increased from 24 to 72 h, which reduced the water wetting angle from 112 ± 3.5° to 94 ± 3.3°. The wax coating reduced the strength of CyC5 hydrate adhesion by up to nearly 20-fold by reversing the substrate wettability and affecting the hydrate morphol. The measurements performed on scales indicate that calcium carbonate scales strengthen the adhesion strength because of the decrease in the water wetting angle. In addn., honeycomb holes on the surface reduce amplification. Furthermore, settling quartz sand on the wall reduced the adhesion strengths by decreasing the effective sintering area of the hydrate on the underlying base. Finer sand and higher concns. led to lower strengths. On the basis of the verified linear correlation between the hydrate adhesion strength and the adhesion work of droplets on different substrates and the influence of water conversion during deposition, both an equation and a key const. parameter were obtained to predict the sintered hydrate deposit adhesion strengths on substrates.
- 12Heath, S. M.; Juliussen, B.; Chen, P.; Chen, T.; Benvie, R. Novel Scale Squeeze Technology and Treatment Designs for Improving Scale Inhibitor Retention and Treatment Lifetimes-Use of Ionic Polymers in the Overflush. In SPE International Conference on Oilfield Scale; Society of Petroleum Engineers, 2012.Google ScholarThere is no corresponding record for this reference.
- 13Jordan, M. M.; Mackay, E. J.; Vazquez, O. The Influence Of Overflush Fluid Type On Scale Squeeze Life Time-Field Examples And Placement Simulation Evaluation. In CORROSION 2008; NACE International, 2008.Google ScholarThere is no corresponding record for this reference.
- 14Zhang, P.; Liu, Y.; Kan, A. T.; Tomson, M. B. Laboratory Evaluation of Synergistic Effect of Transition Metals with Mineral Scale Inhibitor in Controlling Halite Scale Deposition. J. Pet. Sci. Eng. 2019, 175, 120– 128, DOI: 10.1016/j.petrol.2018.12.036Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisFGhsrjE&md5=d7720a60c9fc49346acf1f05aa0b2617Laboratory evaluation of synergistic effect of transition metals with mineral scale inhibitor in controlling halite scale depositionZhang, Ping; Liu, Yuan; Kan, Amy T.; Tomson, Mason B.Journal of Petroleum Science & Engineering (2019), 175 (), 120-128CODEN: JPSEE6; ISSN:0920-4105. (Elsevier B.V.)Sodium chloride (halite) has been traditionally regarded as an unconventional oilfield mineral scale, compared with more prevalent carbonate and sulfate scales. However, with the increasing productions from offshore deepwater and shale gas fields, halite scale occurrence becomes more frequent, leading to significant tech. and financial challenges to productions. Although low-salinity water diln. remains the primary approach in controlling halite scale threat, chem. inhibition has been evaluated as an alternative halite control strategy due to the intrinsic issues assocd. with low-salinity water availability and water quality. There are limited studies concerning the combined effect of metals, esp. transition metals with scale inhibitors in halite control. In this study, the combined effect of a no. of transition metal ions with two common halite scale inhibitors was evaluated in a lab. setup. It was found that among the transition metals studied, Pb2+ ion demonstrates a synergistic effect with the scale inhibitors evaluated by considerably extending the halite induction time. The calcd. inhibition efficiency also indicates that the presence of Pb2+ improves inhibitor performance. Although Pb2+ is an environmental pollutant, an aq. Pb2+ concn. of up to 10 mg L-1 can naturally occur in both natural gas produced water and oilfield produced water. The operators can take advantage of the reported synergistic effect of Pb2+ with scale inhibitors in this study while designing field halite control strategy. The enhanced inhibition efficiency elaborated in this study can be useful in designing the halite scale control strategy, if a decent amt. of Pb2+ is present in the produced water.
- 15Zhang, P.; Liu, Y.; Zhang, N.; Ip, W. F.; Kan, A. T.; Tomson, M. B. A Novel Attach-and-Release Mineral Scale Control Strategy: Laboratory Investigation of Retention and Release of Scale Inhibitor on Pipe Surface. J. Ind. Eng. Chem. 2019, 70, 462– 471, DOI: 10.1016/j.jiec.2018.11.009Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXit1yls7jK&md5=1b448fa82c64ee2dd12232e67d7dfc49A novel attach-and-release mineral scale control strategy: Laboratory investigation of retention and release of scale inhibitor on pipe surfaceZhang, Ping; Liu, Yuan; Zhang, Nan; Ip, Weng Fai; Kan, Amy T.; Tomson, Mason B.Journal of Industrial and Engineering Chemistry (Amsterdam, Netherlands) (2019), 70 (), 462-471CODEN: JIECFI; ISSN:1226-086X. (Elsevier B.V.)A novel "attach-and-release" approach has been exptl. evaluated as an alternative scale control strategy for pipe flow system. Phosphonate scale inhibitor was initially attached to calcium carbonate medium on the surface of the pipe. Subsequently, the retained inhibitor was released into the flowing fluid for scale control. A plug-flow tube reactor app. was adopted in lab. studies. It shows that formation of calcium-inhibitor ppt. accounts for the attachment of inhibitor and brine chem. can considerably impact the amt. of inhibitor retained. This proposed strategy has the potential to be applied in a pipe flow system to control scale deposition threat.
- 16Yan, F.; Zhang, F.; Bhandari, N.; Wang, L.; Dai, Z.; Zhang, Z.; Liu, Y.; Ruan, G.; Kan, A.; Tomson, M. Adsorption and Precipitation of Scale Inhibitors on Shale Formations. J. Pet. Sci. Eng. 2015, 136, 32– 40, DOI: 10.1016/j.petrol.2015.11.001Google Scholar16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhslyrtb7N&md5=795d474452e744700c12e8bc389150e8Adsorption and precipitation of scale inhibitors on shale formationsYan, Fei; Zhang, Fangfu; Bhandari, Narayan; Wang, Lu; Dai, Zhaoyi; Zhang, Zhang; Liu, Ya; Ruan, Gedeng; Kan, Amy; Tomson, MasonJournal of Petroleum Science & Engineering (2015), 136 (), 32-40CODEN: JPSEE6; ISSN:0920-4105. (Elsevier B.V.)Scale inhibitor is one of the most important ingredients in hydraulic fracturing fluids for shale gas prodn. However, the adsorption and pptn. behaviors of scale inhibitors on shale formations have never been reported. The objective of this study is to develop mechanistic understanding of interactions between common scale inhibitors and shale formations so that we can predict the fate and transport of scale inhibitors in shale formations. The adsorption and pptn. of DTPMP and PPCA on Eagle Ford and Marcellus shales were studied in batch reactors at oil field temp. of 70 °C. The adsorption kinetics shows a fast adsorption process of inhibitors on shales, and inhibitor concns. reach equil. between 4 and 8 h. In batch adsorption isotherm expts., initial concns. of scale inhibitors in aq. phase varied from 5 ppm to 44,000 ppm. At low DTPMP concn. ranges, surface adsorption occurs on both Eagle Ford and Marcellus. Above certain concns., DTPMP and calcium forms ppt. on Eagle Ford, which increases the attachment, and slightly acidic pH and high calcium concns. enhance the pptn. The adsorption of PPCA on Eagle Ford was more significant at slightly acidic conditions, and PPCA adsorption onto Marcellus did not exhibit a notable difference between different pH conditions. Due to the strong chelating effect of DTPMP and PPCA, iron was extd. from Marcellus under high inhibitor concns.
- 17Pairat, R.; Sumeath, C.; Browning, F. H.; Fogler, H. S. Precipitation and Dissolution of Calcium– ATMP Precipitates for the Inhibition of Scale Formation in Porous Media. Langmuir 1997, 13 (6), 1791– 1798, DOI: 10.1021/la9608425Google Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXhvFGgsLc%253D&md5=e622c2c731c021e748d44fb5af46c3b7Precipitation and Dissolution of Calcium-ATMP Precipitates for the Inhibition of Scale Formation in Porous MediaPairat, R.; Sumeath, C.; Browning, F. Henry; Fogler, H. ScottLangmuir (1997), 13 (6), 1791-1798CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)The pptn. reaction between aminotris(methylenephosphonic acid) (ATMP) and calcium was systematically studied in an effort to design scale control systems, esp. in petroleum recovery. By varying the pptg. conditions, three distinct ppts. formed: (1) a cryst., sheetlike, 1:1 calcium-ATMP ppt., (2) an amorphous, spherical-shaped, 2:1 calcium-ATMP ppt., and (3) an amorphous, spherical-shaped, 3:1 calcium-ATMP ppt. Corresponding batch dissoln. expts. showed that as the ppt. calcium-ATMP molar ratio increased from 1:1 to 2:1 to 3:1, the rate of dissoln. and the equil. soly. limit decreased significantly. The significance of these observations was evident when the release characteristics of each ppt. from porous media were studied as related to ATMP use in petroleum-recovery systems. The 3:1 calcium-ATMP ppt. was released from porous media in a much slower manner than the other two ppts., strongly suggesting that the 3:1 ppt. is most suitable for use in petroleum recovery.
- 18Jarrahian, K.; Sorbie, K. S. Mechanistic Investigation of Adsorption Behaviour of Two Scale Inhibitors on Carbonate Formations for Application in Squeeze Treatments. Energy Fuels 2020, 34, 4484, DOI: 10.1021/acs.energyfuels.0c00326Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXksVGmu7s%253D&md5=5e969d629fbea5f8347d2c9444571f23Mechanistic Investigation of Adsorption Behavior of Two Scale Inhibitors on Carbonate Formations for Application in Squeeze TreatmentsJarrahian, Khosro; Sorbie, Ken. S.Energy & Fuels (2020), 34 (4), 4484-4496CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Understanding the mechanisms of scale inhibitor (SI) retention in carbonate formations is key to designing efficient SI "squeeze" treatments in oil reservoirs. By performing "apparent adsorption" expts., this paper demonstrates that a coupled adsorption/pptn. (Γ/Π) retention mechanism dominates in calcite and limestone for two widely applied scale inhibitors, DETPMP and PPCA. Pptn. was a more dominant retention mechanism at both initial pH values (pH0 4 and 6) and T = 80 and 95°C for both SIs. At 95°C, the pure adsorption (Γ) region only extends up to [SI] ~ 100 ppm, above which pptn. (Π) dominates. At lower temps. (T = 80°C), the soly. of the SI-M2+ complex increases, resulting in less pptn. The apparent adsorption results are supplemented by measuring the corresponding soln. [Ca2+], pH values in soln., and environmental SEM/energy dispersive X-ray anal. (ESEM/EDX) and particle size anal. (PSA), which give us a full mechanistic explanation of our results. For DETPMP, the retention increased as the soln. pH increased, while retention of PPCA increased as the test pH decreased. Moreover, DETPMP was retained more than PPCA due to their differences in chem. Furthermore, the retention of both SIs was greater for the limestone sample due to Fe2+ traces enhancing the ppt. of SI-M2+.
- 19Patterson, D.; Kendrick, M.; Williams, W.; Jordan, M. M. Squimulation”--Simultaneous Well-Stimulation and Scale-Squeeze Treatments in Deepwater West Africa. SPE Prod. Oper. 2013, 28 (01), 55– 66, DOI: 10.2118/151863-PAGoogle Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXksVGrsbY%253D&md5=ef72ff1c0e21f37549ec9ae948d2fc4e"Squimulation"-simultaneous well-stimulation and scale-squeeze treatments in deepwater west AfricaPatterson, D.; Kendrick, M.; Williams, W.; Jordan, M.SPE Production & Operations (2013), 28 (1), 55-66CODEN: SPEPCW; ISSN:1930-1855. (Society of Petroleum Engineers)In a deepwater west African field, the relatively small no. of high-cost, highly productive wells, coupled with a high barium sulfate scaling tendency (upon waterflood breakthrough of injected seawater) requires effective scale management along with removal of near-wellbore damage in order to achieve high hydrocarbon recovery. The nature of the well-completion strategy in the field (frac packs for sand control) had resulted in some wells with higher than expected skin values owing to drilling-fluid losses, residual fracture gel, fluid loss agents, and fines mobilization within the frac packs. The paper will present how the challenges of managing impaired completions and inorg. scale forced innovation in terms of when to apply both stimulation and scale-inhibitor packages to deepwater wells. This paper will outline a novel process for non-conventional batch chem. applications where bullhead stimulation treatments have been displaced deep into the formation (>20 ft) using a scale inhibitor overflush. Not only does this benefit the stimulation by displacing the spent acid and reagents away from the immediate wellbore area, but the combined treatment provides a cost savings with a single mobilization for the combined treatment. The paper will describe the lab. testing that was performed to qualify the treatments. The four field treatments that were performed demonstrate how these coupled applications have proven very effective at both well stimulation/skin redn. and scale-inhibitor placement before and after seawater breakthrough. The term "squimulation" is used by the local operations team to describe this simultaneous squeeze-and-stimulation process. Many similar fields are currently being developed in the Campos basin (Gulf of Mexico) and west Africa, and this paper presents a good example of best-practice sharing from another oil basin.
- 20Paukert Vankeuren, A. N.; Hakala, J. A.; Jarvis, K.; Moore, J. E. Mineral Reactions in Shale Gas Reservoirs: Barite Scale Formation from Reusing Produced Water as Hydraulic Fracturing Fluid. Environ. Sci. Technol. 2017, 51 (16), 9391– 9402, DOI: 10.1021/acs.est.7b01979Google Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtF2it77L&md5=d3eb1fc4714d9eb87b71221214788bc0Mineral Reactions in Shale Gas Reservoirs: Barite Scale Formation from Reusing Produced Water As Hydraulic Fracturing FluidPaukert Vankeuren, Amelia N.; Hakala, J. Alexandra; Jarvis, Karl; Moore, Johnathan E.Environmental Science & Technology (2017), 51 (16), 9391-9402CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)Hydraulic fracturing for gas prodn. is now ubiquitous in shale plays, but relatively little is known about shale-hydraulic fracturing fluid (HFF) reactions within the reservoir. To investigate reactions during the shut-in period of hydraulic fracturing, expts. were conducted flowing different HFFs through fractured Marcellus shale cores at reservoir temp. and pressure (66 °C, 20 MPa) for one week. Results indicate HFFs with hydrochloric acid cause substantial dissoln. of carbonate minerals, as expected, increasing effective fracture vol. (fracture vol. + near-fracture matrix porosity) by 56-65%. HFFs with reused produced water compn. cause pptn. of secondary minerals, particularly barite, decreasing effective fracture vol. by 1-3%. Barite pptn. occurs despite the presence of antiscalants in expts. with and without shale contact and is driven in part by addn. of dissolved sulfate from the decompn. of persulfate breakers in HFF at reservoir conditions. The overall effect of mineral changes on the reservoir has yet to be quantified, but the significant amt. of barite scale formed by HFFs with reused produced water compn. could reduce effective fracture vol. Further study is required to extrapolate exptl. results to reservoir-scale and to explore the effect that mineral changes from HFF interaction with shale might have on gas prodn.
- 21Kan, A. T.; Fu, G.; Tomson, M. B.; Al-Thubaiti, M.; Xiao, A. J. Factors Affecting Scale Inhibitor Retention in Carbonate-Rich Formation during Squeeze Treatment. Spe J. 2004, 9 (03), 280– 289, DOI: 10.2118/80230-PAGoogle Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXovFWmtbs%253D&md5=7217bd3b2c9873218e2e2126be306c7fFactors affecting scale inhibitor retention in carbonate-rich formation during squeeze treatmentKan, Amy T.; Fu, Gongmin; Tomson, Mason B.; Al-Thubaiti, Musaed; Xiao, Alan J.SPE Journal (Society of Petroleum Engineers) (2004), 9 (3), 280-289CODEN: SPJRFW; ISSN:1086-055X. (Society of Petroleum Engineers Inc.)Significant progress has been made toward developing a quant. understanding of the inhibitor/rock interaction. In this study, four common oil field inhibitors (three phosphonates and one polyacrylate) are compared using carbonate-rich formation rocks. In addn. to calcite (CaCO3) in the reservoir rock, several calcium inhibitor (Inh) solid phases are also important. Two reactions are central to the inhibitor retention in carbonate-rich formation: first, redn. of calcite dissoln. because of surface poisoning by the Ca-Inh coating; and second, pptn. of Ca-Inh solid with either low Ca or high Ca stoichiometry. For aminotri(methylene phosphonic acid) (NTMP), an acidic Ca-NTMP salt is formed at a low-pH environment. In addn., two cryst. Ca-NTMP phases and an amorphous Ca-NTMP salt may form, depending on the aquatic environment. Quant. relationships between types of inhibitors, inhibitor acidity and concn., and kinetics of calcite dissoln. and calcium-phosphonate pptn. are developed. Consequences of the observations on squeeze design and scale inhibition are discussed.
- 22Vazquez, O.; Fursov, I.; Mackay, E. Automatic Optimization of Oilfield Scale Inhibitor Squeeze Treatment Designs. J. Pet. Sci. Eng. 2016, 147, 302– 307, DOI: 10.1016/j.petrol.2016.06.025Google Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtVGmt7vE&md5=872cfa2be7a0996a46210651c9dd0d2dAutomatic optimization of oilfield scale inhibitor squeeze treatment designsVazquez, Oscar; Fursov, Ilya; Mackay, EricJournal of Petroleum Science & Engineering (2016), 147 (), 302-307CODEN: JPSEE6; ISSN:0920-4105. (Elsevier B.V.)Squeeze treatments are one of the most common methods to prevent oilfield scale deposition, which in turn is one of the most significant flow assurance challenges in the oil industry. Squeeze treatments consist of the batch injection of a chem. scale inhibitor (SI), which above a certain concn., commonly known as MIC (Min. Inhibitor Concn.), prevents scale deposition. The most important factor in a squeeze treatment design is the squeeze lifetime, which is detd. by the vol. of water or days of prodn. where the chem. return concn. is above MIC, which commonly is between 1 and 20 ppm. Typically, squeeze treatment designs include the following four stages: a preflush, acting as a buffer; the main slug, where the main chem. slug is injected; the overflush, which will displaced the chem. pill deeper into the formation and finally, a shut-in stage, which allows the chem. to be further retained in the formation. The main purpose of this paper is to describe the automatic optimization of squeeze treatment designs using an optimization algorithm, in particular, using particle swarm optimization (PSO). The algorithm provides the optimum design for a given set of criteria that are used in a purpose built reactive transport model of the near-wellbore area. Every squeeze design is fully detd. by a no. of parameters; namely, injected inhibitor concn., main slug vol., overflush vol. and shut-in time. The parameter space is bound to certain limits, which will be detd. by the max. injected concn., main slug and overflush vols. The max. injected concn. might be detd. by, amongst other issues, logistics, economics and/or compatibility with other chems. The main slug and overflush max. vols. may be identified by the well engineer based on concerns of water formation damage, hydrate formation and/or gas lifting limitations, which might be lower for high value wells. This approach still requires engineering input and review, but speeds up the process of finding an optimum design, and reduces risk of non-optimal squeeze treatments being performed.
- 23Kahrwad, M.; Sorbie, K. S.; Boak, L. S. Coupled Adsorption/Precipitation of Scale Inhibitors: Experimental Results and Modeling. SPE Prod. Oper. 2009, 24 (03), 481– 491, DOI: 10.2118/114108-PAGoogle Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtFags7zM&md5=a31ea52067661556f548866892c1e37bCoupled adsorption/precipitation of scale inhibitors: experimental results and modelingKahrwad, M.; Sorbie, K. S.; Boak, L. S.SPE Production & Operations (2009), 24 (3), 481-491CODEN: SPEPCW; ISSN:1930-1855. (Society of Petroleum Engineers)In this paper, results are presented on the general mechanisms by which scale inhibitors (SIs) are retained within porous media. There is a generally accepted view that the main two mechanisms of SI retention are "adsorption" and "pptn.," and these are described by different but related modeling approaches in the literature. These approaches have been used quite successfully to model field squeeze treatments. To analyze in a detailed and unambiguous manner where a given retention mechanism (e.g., pure adsorption) or mechanisms (e.g., coupled adsorption and pptn.) are operating requires that we carry out careful lab. expts. under "field relevant" conditions. In this work, we study adsorption vs. adsorption/pptn. by performing a series of expts. where we know that the system exhibits either (a) adsorption only or (b) coupled adsorption/pptn. Exptl., it is straightforward to det. which regime the system is in. We present the theory describing the coupled adsorption/pptn. process. In addn., an extensive series of exptl. adsorption/pptn. measurements is presented for various mineral separates including sand, chlorite, siderite, muscovite, kaolinite, and feldspar. The coupled adsorption/pptn. model is in very good agreement with the expt.
- 24Park, W. K.; Ko, S.-J.; Lee, S. W.; Cho, K.-H.; Ahn, J.-W.; Han, C. Effects of Magnesium Chloride and Organic Additives on the Synthesis of Aragonite Precipitated Calcium Carbonate. J. Cryst. Growth 2008, 310 (10), 2593– 2601, DOI: 10.1016/j.jcrysgro.2008.01.023Google Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXls1Sku70%253D&md5=c2866c8cf6005d37f09755f3c434be3cEffects of magnesium chloride and organic additives on the synthesis of aragonite precipitated calcium carbonatePark, Woon Kyoung; Ko, Sang-Jin; Lee, Seung Woo; Cho, Kye-Hong; Ahn, Ji-Whan; Han, ChoonJournal of Crystal Growth (2008), 310 (10), 2593-2601CODEN: JCRGAE; ISSN:0022-0248. (Elsevier B.V.)The synthesis of aragonite pptd. calcium carbonate by treating a suspension of Ca(OH)2 with CO2 gas was investigated with regard to the effects of Mg2+ ions and org. additives on polymorphism and alternative orientations. In the presence of a small amt. of Mg2+, Mg-calcite formed, but as the Mg2+ ion concn. increased, the amt. of Mg-calcite decreased and the amt. of aragonite increased. Thus, the formation of Mg-calcite is suppressed and only aragonite is formed in the presence of 60 mol% MgCl2. As the Mg2+ ion concn. increased, the aragonite that formed was found to have decreased in terms of its longitude and aspect ratio. Furthermore, the effect of Mg2+ ions in conjunction with org. additives was also investigated with regard to polymorphs and morphol. and the structure-forming properties of the org. additives.
- 25Tomson, M. B.; Kan, A. T.; Fu, G. Control of Inhibitor Squeeze Through Mechanistic Understanding of Inhibitor Chemistry. SPE J. 2006, 11 (03), 283– 293, DOI: 10.2118/87450-PAGoogle Scholar25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XhtFChtLbM&md5=ed5da1513cd71be0d89b2621b7d415b5Control of scale inhibitor squeeze through mechanistic understanding of inhibitor chemistryTomson, Mason B.; Kan, Amy T.; Fu, GongminSPE Journal (Society of Petroleum Engineers) (2006), 11 (3), 283-293CODEN: SPJRFW; ISSN:1086-055X. (Society of Petroleum Engineers Inc.)Chem. scale inhibitors are commonly used to prevent or inhibit scale formation in oil wells. The most economic treatment of scale inhibitor is normally through chem. squeeze. However, there is little agreement regarding the primary mechanism by which the threshold scale inhibitors are retained in producing oil or gas formations as a result of squeeze procedures. Recent advances in phosphonate/rock interaction research at the Rice U. Brine Chem. Consortium have significantly improved our knowledge of what controls inhibitor placement in the formation. The pill chem. is also an important determinant for retention of carbonate reservoir. Acidic pills are mostly retained near the wellbore, while more neutralized pills move farther into the formation. Three calcium nitrilomethylene phosphonate solid phases, an amorphous phase, and two cryst. Ca2.5HNTMP phases with pKsp = 22.6 and pKsp = 24.2 are particularly important for inhibitor retention. The relative sizes of these solid phases formed are governed by the pill compn. and acidity. These results can be explained by a soln.-phase-controlled sequence of reactions. All of this information has been incorporated into a new squeeze-design software program, SqueezeSoftPitzer.
- 26Vazquez, O.; Thanasutives, P.; Eliasson, C.; Fleming, N.; Mackay, E. Modeling the Application of Scale-Inhibitor-Squeeze Retention-Enhancing Additives. SPE Prod. Oper. 2011, 26 (03), 270– 277, DOI: 10.2118/141384-PAGoogle Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtVCnu7nM&md5=7f9d740d7b04bc6b256d0fb8cfdb805fModeling the application of scale-inhibitor-squeeze-retention-enhancing additivesVazquez, O.; Thanasutives, P.; Eliasson, C.; Fleming, N.; Mackay, E.SPE Production & Operations (2011), 26 (3), 270-277CODEN: SPEPCW; ISSN:1930-1855. (Society of Petroleum Engineers)The most common method for preventing scale formation is by applying a scale-inhibitor (SI) squeeze treatment. In this process, an SI soln. is injected down a producer well into the near-wellbore formation. In the last few years, several publications have presented exptl. results, field data, and treatment methods showing enhanced squeeze lifetime because of the use of squeeze enhancers. The main purpose of this paper is to model the effect of SI-retention-enhancing additives. These additives are normally deployed in reservoirs where the SI shows poor retention in the formation matrix in order to reduce well interventions. In the last few years, a no. of techniques to enhance the SI retention have been reported in the literature, such as pptn. squeezes using calcium and/or pH-increasing additives, use of an additive package that enhances SI adsorption by crosslinking, and the injection of nondamaging concns. of kaolinite, calcium carbonate, and organosilane (a solids-fixation agent). The effect of the SI-retention enhancer is modeled as a function of the adsorption level of the additive. A sensitivity study is then presented on the effect of deploying the additive in the different stages; normally, they are deployed in the preflush stage. However, the aim of this paper is to investigate how the treatment could be optimized to achieve the longest squeeze lifetime with a fixed amt. of additive. An example of modeling a specific field treatment injecting organosilane is included. The results are compared with the field return profiles and clearly demonstrate the value such modeling can bring to the interpretation and design of field squeezes.
- 27Baraka-Lokmane, S.; Sorbie, K. S. Scale Inhibitor Core Floods in Carbonate Cores: The Influence of PH on Phosphonate-Carbonate Interactions. In SPE International Symposium on Oilfield Scale; Society of Petroleum Engineers, 2004.Google ScholarThere is no corresponding record for this reference.
- 28Baraka-Lokmane, S.; Sorbie, K. S. Scale Inhibitor Core Floods in Carbonate Cores: Chemical Interactions and Modelling. In SPE International Oilfield Scale Symposium; Society of Petroleum Engineers, 2006.Google ScholarThere is no corresponding record for this reference.
- 29Kan, A. T.; Fu, G.; Tomson, M. B. Adsorption and Precipitation of an Aminoalkylphosphonate onto Calcite. J. Colloid Interface Sci. 2005, 281 (2), 275– 284, DOI: 10.1016/j.jcis.2004.08.054Google Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXhtVaitrbJ&md5=eb6520b1d8afc023a8a2bdb7a3ec0e93Adsorption and precipitation of an aminoalkylphosphonate onto calciteKan, Amy T.; Fu, Gongmin; Tomson, Mason B.Journal of Colloid and Interface Science (2005), 281 (2), 275-284CODEN: JCISA5; ISSN:0021-9797. (Elsevier)The mechanism of nitrilotris(methylenephosphonic acid) (H6NTMP)/calcite reaction was studied with a large no. of batch expts. where phosphonic acid was neutralized with 0 to 5 equiv of NaOH per phosphonic acid and the concn. ranged from ∼10 nmol/L to 1 mol/L. Probably the phosphonate/calcite reactions are characterized in 3 steps. At low phosphonate concn. (<1 μmol/L NTMP concn.), the phosphonate/calcite reaction can be characterized as a Langmuir isotherm. At satn., only ∼7% of the calcite surface is covered with phosphonate; presumably these are the kinks, step edges, or other imperfect sites. At higher phosphonate concns., the attachment is characterized by Ca phosphonate crystal growth to a max. of 4 to 5 surface layer thick, with solid phase stoichiometry of Ca2.5HNTMP and a const. soly. product of 10-24.11. After multiple layers of phosphonate are formed on the calcite surface, the soln. is no longer at equil. with calcite. Further phosphonate retention is probably due to mixed Ca phosphonate solid phase formation at lower pH and depleted soln. phase Ca conditions. The proposed mechanism is consistent with phosphate/calcite reaction and can be used to explain the fate of phosphonate in brines from oil producing wells and the results are compared with 2 oil wells.
- 30Baraka-Lokmane, S.; Sorbie, K. The Role of Calcium and Magnesium in the Mechanism of the Scale Inhibitor Retention in Carbonate Systems. In AAPG European Region Energy Conference and Exhibition ; 2007.Google ScholarThere is no corresponding record for this reference.
- 31Sorbie, K. S.; Wat, R. M. S.; Todd, A. C. Interpretation and Theoretical Modeling of Scale-Inhibitor/Tracer Corefloods. SPE Prod. Eng. 1992, 7 (03), 307– 312, DOI: 10.2118/20687-PAGoogle Scholar31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK38XmtFGktLo%253D&md5=414230d983a11999f72cadf7e22d377cInterpretation and theoretical modeling of scale-inhibitor/tracer corefloodsSorbie, K. S.; Wat, R. M. S.; Todd, A. C.SPE Production Engineering (1992), 7 (3), 307-12CODEN: SPENES; ISSN:0885-9221.This paper describes a theor. approach to det. the inhibitor dynamic adsorption isotherm from coreflood expts. The main feature of the isotherm that contributes principally to the long squeeze life is highlighted. The problems of modeling near-well squeeze treatments and an improved simulator are discussed.
- 32Jarrahian, K.; Boak, L. S.; Graham, A. J.; Singleton, M. A.; Sorbie, K. S. Experimental Investigation of the Interaction between a Phosphate Ester Scale Inhibitor and Carbonate Rocks for Application in Squeeze Treatments. Energy Fuels 2019, 33 (5), 4089– 4103, DOI: 10.1021/acs.energyfuels.9b00382Google Scholar32https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXmt1Olt7k%253D&md5=b0d1457ad98294f6e3e26b2e5511ee4aExperimental Investigation of the Interaction between a Phosphate Ester Scale Inhibitor and Carbonate Rocks for Application in Squeeze TreatmentsJarrahian, Khosro; Boak, Lorraine S.; Graham, Alexander J.; Singleton, Mike A.; Sorbie, Ken. S.Energy & Fuels (2019), 33 (5), 4089-4103CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Studying the interaction between scale inhibitors (SIs) and chem. reactive carbonate minerals is crucial for detg. SI retention in "squeeze" treatments. This study investigated the retention of the environmentally friendly SI, polyhydric alc. phosphate ester (PAPE), on calcite and dolomite substrates. Elemental anal. of the supernatant soln. as well as pH measurement and environmental SEM (ESEM) with energy dispersive X-ray anal. (EDX) were all used to investigate SI retention and to identify the morphol./compn. of the resultant SI-Ca ppts. Results revealed that PAPE was retained by calcite via pure adsorption at an initial test pH (pH0) of 4 and then pptd. at pH0 6. In contrast, the PAPE/dolomite system was found to be effectively pH-independent, with pptn. dominating at both pH0 values. Any temp. effect was negligible for dolomite/PAPE retention, whereas with calcite, retention was smaller at lower temp., which is attributed to the temp.-dependence of the substrate soly. Overall, the final pH of the system and the resulting degree of SI dissocn. contributed more to PAPE retention than did the final calcium concn. EDX anal. confirmed scale-inhibitor phosphorus in the deposited solids, indicating coupled adsorption/pptn. This phosphorus increased with the amt. of pptn. and with the temp., confirming the corresponding static adsorption test results.
- 33Jarrahian, K.; Sorbie, K.; Singleton, M.; Boak, L.; Graham, A. Building a Fundamental Understanding of Scale-Inhibitor Retention in Carbonate Formations. SPE Prod. Oper. 2019, DOI: 10.2118/193635-MSGoogle ScholarThere is no corresponding record for this reference.
- 34Ibrahim, J. M.; Sorbie, K.; Boak, L. S. Coupled Adsorption/Precipitation Experiments: 1. Static Results. In SPE International Conference on Oilfield Scale; Society of Petroleum Engineers, 2012.Google ScholarThere is no corresponding record for this reference.
- 35Browning, F. H.; Fogler, H. S. Effect of Precipitating Conditions on the Formation of Calcium– HEDP Precipitates. Langmuir 1996, 12 (21), 5231– 5238, DOI: 10.1021/la9603277Google Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28XlvVSltrg%253D&md5=f99d6436f4d87934f976f6bc1a4319e8Effect of Precipitating Conditions on the Formation of Calcium-HEDP PrecipitatesBrowning, F. Henry; Fogler, H. ScottLangmuir (1996), 12 (21), 5231-5238CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)The focus of this paper is to define the conditions under which distinct calcium-phosphonate ppts. will form and to study how each of these ppt.'s unique chem. and phys. properties govern the release of phosphonate from porous media. The phosphonate used in this study was (1-hydroxyethylidene)-1,1-diphosphonic acid (HEDP). By variation of pH and calcium/HEDP molar ratio in soln., two distinct ppts. were formed: (1) a sol., fibrous 1:1 calcium/HEDP ppt.; and (2) a less sol., spherical 2:1 calcium/HEDP ppt. Crit. pH values that define the conditions under which each distinct ppt. forms were identified. Below the first crit. pH value, the 1:1 ppt. formed, while above the second crit. pH value, the 2:1 ppt. formed. Finally, core-flood and micromodel expts. showed that the release of 2:1 ppt. from porous media was significantly slower than that of 1:1 ppt., suggesting that the 2:1 ppt. is better suited for phosphonate treatments in oil field applications. The release of a ppt. mixt. (one which contains both distinct ppts. and has a calcium/HEDP molar ratio of 1.4:1) from a micromodel reconfirmed this phenomenon.
- 36Vetter, O. J. Oilfield Scale---Can We Handle It?. J. Pet. Technol. 1976, 28 (12), 1402, DOI: 10.2118/5879-PAGoogle Scholar36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2sXktVyhsrs%253D&md5=4907a725248da1c34bd9d1b5523316f6Oilfield scale - can we handle it?Vetter, O. J.JPT, Journal of Petroleum Technology (1976), 28 (Dec.), 1402-8CODEN: JPTJAM; ISSN:0149-2136.A review with 8 refs., of the formation, removal, and prevention of the scale of oil and gas fields.
- 37Jordan, M. M.; Sorbie, K. S.; Jiang, P.; Yuan, M. D.; Todd, A. C.; Thiery, L. The Effect of Clay Minerals, pH, Calcium and Temperature on the Adsorption of Phosphonate Scale Inhibitor onto Reservoir Core and Mineral Separates; NACE International: Houston, TX, United States, 1994.Google ScholarThere is no corresponding record for this reference.
- 38Sorbie, K. S.; Gdanski, R. D. A Complete Theory of Scale Inhibitor Transport, Adsorption/Desorption and Precipitation in Squeeze Treatments. In SPE International Symposium on Oilfield Scale; Society of Petroleum Engineers, 2005.Google ScholarThere is no corresponding record for this reference.
- 39Tomson, M. B.; Kan, A. T.; Fu, G.; Shen, D.; Nasr-El-Din, H. A.; Al-Saiari, H.; Al-Thubaiti, M. Mechanistic Understanding of Rock/Phosphonate Interactions and Effect of Metal Ions on Inhibitor Retention. SPE J. 2008, 13 (03), 325– 336, DOI: 10.2118/100494-PAGoogle Scholar39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXht1WmurjP&md5=4dac73d9fd9cd53b39879a6dbbcdb547Mechanistic understanding of rock/phosphonate interactions and the effect of metal ions on inhibitor retentionTomson, Mason B.; Kan, Amy T.; Fu, Gongmin; Shen, Dong; Nasr-El-Din, Hisham A.; Al-Saiari, Hamad; Al-Thubaiti, MusaedSPE Journal (Society of Petroleum Engineers) (2008), 13 (3), 325-336CODEN: SPJRFW; ISSN:1086-055X. (Society of Petroleum Engineers Inc.)This paper discusses the effects of Ca2+, Mg2+, and Fe2+ on inhibitor retention and release. Better understanding of phosphonate reactions during inhibitor squeeze treatments has direct implication on how to design and improve scale inhibitor squeeze treatments for optimum scale control. Putting various amts. of metal ions in the inhibitor pill adds another degree of freedom in squeeze design, esp. in controlling return concns. and squeeze life. Phosphonate reactions during squeeze treatments involve a series of self-regulating reactions with calcite and other minerals. However, excess calcite does not improve the retention of phosphonate due to the surface poisoning effect of Ca2+. The squeeze can be designed so that max. squeeze life is achieved by forming a low soly. phase in the formation. Addn. of Ca2+, Mg2+, and Fe2+ in the pill soln. at 0.1 to 1 molar ratios significantly improves the retention of phosphonate. Alternatively, these metal ions can be dissolved from the formation while an acidic inhibitor pill is in contact with the formation minerals. Both BHPMP and DTPMP returns were significantly extended by the addn. of metal ions (e.g., Ca2+ and Fe2+). The addn. of Mg2+ may increase the long-term return concn., which is important for some wells where a higher inhibitor return concn. is needed. The lab. squeeze simulations were compared to return data obtained from squeeze treatments performed on two wells located in a sandstone reservoir in Saudi Arabia. The sandstone formation contains significant amts. of iron-bearing minerals.
- 40Von Wandruszka, R. Phosphorus Retention in Calcareous Soils and the Effect of Organic Matter on Its Mobility. Geochem. Trans. 2006, 7 (1), 6, DOI: 10.1186/1467-4866-7-6Google Scholar40https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BD28zovFGrtA%253D%253D&md5=eb585bbb3a132f5881ab0b9b949bdb4bPhosphorus retention in calcareous soils and the effect of organic matter on its mobilityvon Wandruszka RayGeochemical transactions (2006), 7 (), 6 ISSN:.A survey of the interactions between phosphorus (P) species and the components of calcareous soils shows that both surface reactions and precipitation take place, especially in the presence of calcite and limestone. The principal products of these reactions are dicalcium phosphate and octacalcium phosphate, which may interconvert after formation. The role of calcium carbonate in P retention by calcareous soils is, however, significant only at relatively high P concentrations - non-carbonate clays play a more important part at lower concentrations. In the presence of iron oxide particles, occlusion of P frequently occurs in these bodies, especially with forms of the element that are pedogenic in origin. Progressive mineralization and immobilization, often biological in nature, are generally observed when P is added as a fertilizer. Manure serves both as a source of subsurface P and an effective mobilizing agent. Blockage of P sorption sites by organic acids, as well as complexation of exchangeable Al and Fe in the soil, are potential causes of this mobilization. Swine and chicken manure are especially rich P sources, largely due the practice of adding the element to the feed of nonruminants. Humic materials, both native and added, appear to increase recovery of Olsen P. In the presence of metal cations, strong complexes between inorganic P and humates are formed. The influence of humic soil amendments on P mobility warrants further investigation.
- 41Matar, A.; Torrent, J.; Ryan, J. Soil and Fertilizer Phosphorus and Crop Responses in the Dryland Mediterranean Zone. In Advances in Soil Science; Springer, 1992; pp 81– 146.Google ScholarThere is no corresponding record for this reference.
- 42Tunesi, S.; Poggi, V.; Gessa, C. Phosphate Adsorption and Precipitation in Calcareous Soils: The Role of Calcium Ions in Solution and Carbonate Minerals. Nutr. Cycl. Agroecosystems 1999, 53 (3), 219– 227, DOI: 10.1023/A:1009709005147Google ScholarThere is no corresponding record for this reference.
- 43Sorbie, K. S.; Jiang, P.; Yuan, M. D.; Chen, P.; Jordan, M. M.; Todd, A. C. The Effect of PH, Calcium, and Temperature on the Adsorption of Phosphonate Inhibitor onto Consolidated and Crushed Sandstone. In SPE Annual Technical Conference and Exhibition; Society of Petroleum Engineers, 1993.Google ScholarThere is no corresponding record for this reference.
- 44Tantayakom, V.; Fogler, H. S.; Charoensirithavorn, P.; Chavadej, S. Kinetic Study of Scale Inhibitor Precipitation in Squeeze Treatment. Cryst. Growth Des. 2005, 5 (1), 329– 335, DOI: 10.1021/cg049874dGoogle Scholar44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXhtVCrsbrL&md5=266b7b8931207fe89aefd2c2a8bbc7a7Kinetic Study of Scale Inhibitor Precipitation in Squeeze TreatmentTantayakom, V.; Fogler, H. S.; Charoensirithavorn, P.; Chavadej, S.Crystal Growth & Design (2005), 5 (1), 329-335CODEN: CGDEFU; ISSN:1528-7483. (American Chemical Society)Oilfield formation damage by scale formation can occur when two incompatible brine streams are mixed. A common method for preventing scale formation is the use of chem. scale inhibitors such as aminotri(methylene phosphonic acid) (ATMP). Scale inhibitors are injected and retained in the reservoir by adsorption and/or pptn. The induction time, the period between the establishment of supersatn. and the detection of a new phase, is a measure of the ability of an inhibitor soln. to remain in the metastable state. As a result, long induction times allow transport of inhibitor fluids into the near-wellbore regions without pptn. of the scale inhibitor and subsequent formation damage. In this study, an induction time model is applied to pptn. of the inhibitor (ATMP) with Ca2+ ions. The nucleation kinetics can be described by classical nucleation theory. Soln. equil. was calcd. by accounting for inhibitor dissocn. and cation-inhibitor complexing as a function of ionic strength. Conditions such as the initial concn. of inhibitor, the soln. pH, and the presence of sol. impurities significantly impact the pptn. kinetics of inhibitors. Long induction times were obsd. at low initial concns. of inhibitor, at low values of the soln. pH, and in the presence of impurities. Monovalent cation impurities (Li, Na, and K) inhibit the nucleation of Ca-ATMP to the same extent, indicating there is no effect on the different types of monovalent cations. Divalent cation impurities inhibit the nucleation of Ca-ATMP more than monovalent cations, and different divalent cations have different induction times. The redn. of nucleation rate is a result of increasing the surface free energy. This study provides an understanding of scale inhibitor pptn. kinetics which will be beneficial for delaying inhibitor pptn. in order to avoid reservoir permeability problems in near-wellbore region.
- 45Jarrahian, K.; Singleton, M.; Boak, L.; Sorbie, K. S. Surface Chemistry of Phosphonate Scale Inhibitor Retention Mechanisms in Carbonate Reservoirs. Cryst. Growth Des. 2020, 20 (8), 5356– 5372, DOI: 10.1021/acs.cgd.0c00570Google Scholar45https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVSms7vP&md5=63180c6041e121b45968c78409e5453fSurface Chemistry of Phosphonate Scale Inhibitor Retention Mechanisms in Carbonate ReservoirsJarrahian, Khosro; Singleton, Mike; Boak, Lorraine; Sorbie, Kenneth S.Crystal Growth & Design (2020), 20 (8), 5356-5372CODEN: CGDEFU; ISSN:1528-7483. (American Chemical Society)Building a fundamental understanding of the reactions between scale inhibitor (SI) and formation minerals is essential for effectively designing SI "squeeze" treatments. Results of bulk "apparent adsorption" (Γapp) expts. are presented for a widely used phosphonate SI, DETPMP, on calcite and dolomite mineral substrates. The apparent adsorption results are supported by (i) measuring the corresponding soln. [Ca2+] and pH values in soln., (ii) studying the surface chem. of the resulting SI/Ca ppts. using environmental SEM-energy-dispersive X-ray (ESEM-EDX) anal. to identify the morphol./compn. of the SI/Ca ppts., and (iii) a detailed mass balance anal., indicating the fate of the Ca2+ and the SI. Results revealed that DETPMP was dominantly retained by both calcite and dolomite via a pptn. mechanism (actually coupled adsorption/pptn.) for all initial pH values (pH0 2, 4, and 6) and T = 95°C, although a small region of pure adsorption (Γ) was obsd. at [DETPMP] < 100 ppm. Moreover, higher Γapp occurred on dolomite than on calcite for all initial pH0. This result is counterintuitive, because it is well-known that calcite is much more reactive than dolomite. However, final equil. pH values are higher for dolomite, compared to calcite. Thus, a higher pHfinal led to a more dissocd. DETPMP and this effect had a greater effect on SI/Ca pptn. than the higher [Ca2+] by rock dissoln. EDX anal. confirmed scale-inhibitor phosphorus in the deposited solids, indicating coupled adsorption/pptn. Supporting mass balance calcns. correlated very well with our exptl. observations, showing higher generated calcium in calcite than dolomite and less calcium generation at higher initial pH0 (lower rock dissoln.). Finally, an equil. mechanistic model describing the inhibitor dissocn., Ca-binding to the dissocd. SI species, and pptn. of the SI_Can complex, coupled to the carbonate system, is proposed to qual. explain these exptl. findings. The current work is focused on the results of bulk "apparent adsorption" (Γapp) expts. for a widely used phosphonate scale inhibitor (SI), DETPMP, on calcite and dolomite mineral substrates. The apparent adsorption results are supported by (i) measuring the corresponding soln. [Ca2+] and pH values in soln., (ii) studying the surface chem. of the resulting SI/Ca ppts. using environmental SEM energy-dispersive X-ray (ESEM-EDX) anal. to identify the morphol./compn. of the SI/Ca ppts., and (iii) a detailed mass balance anal., indicating the fate of the Ca2+ and the SI.
- 46Jarrahian, K.; Sorbie, K. S.; Singleton, M. A.; Boak, L. S.; Graham, A. J. The Effect of pH and Mineralogy on the Retention of Polymeric Scale Inhibitors on Carbonate Rocks for Application in Squeeze Treatments. SPE Prod. Oper. 2019, 34 (02), 344– 360, DOI: 10.2118/189519-PAGoogle Scholar46https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXht1ehtrvJ&md5=b01374514847759ecd6cabdeff8c52a1The effect of pH and mineralogy on the retention of polymeric scale inhibitors on carbonate rocks for precipitation squeeze treatmentsJarrahian, K.; Sorbie, K. S.; Singleton, M. A.; Boak, L. S.; Graham, A. J.SPE Production & Operations (2019), 34 (2), 344-360CODEN: SPEPCW; ISSN:1930-1863. (Society of Petroleum Engineers)The bulk "apparent adsorption" behavior (Γapp, vs. Cf) of 2 polymeric scale inhibitors (SI), polyphosphino carboxylic acid (PPCA) and phosphorus-functionalized copolymer (PFC), onto carbonate mineral substrates has been studied for initial soln. pH of 2, 4 and 6. The 2 carbonate minerals used, calcite and dolomite, are much more chem. reactive than sandstone minerals. In nearly all cases, ppts. formed at higher SI concns. were due to the formation of sparingly sol. SI/Ca complexes. A systematic study has been carried out on the SI/Ca ppts. formed, by applying both ESEM/EDX and particle size anal. (PSA). For PPCA, at all pH values, regions of pure adsorption (Γ) and coupled adsorption/pptn. (Γ/Π) are clearly obsd. for both calcite and dolomite. PFC at pH values of 4 and 6 also showed very similar behavior, with a region of pure adsorption (Γ) for PFC < 500 ppm and a region of coupled adsorption/pptn. (Γ/Π) above this level. However, the PFC/calcite case at pH = 2 showed only pure adsorption, while the PFC/dolomite case at pH = 2 again showed coupled adsorption/ pptn. at higher PFC concns. For both SIs on both carbonate substrates, pptn. is the more dominant mechanism for SI retention than adsorption. We discuss here how these observations are related to the reactivity of the different carbonate minerals, the resulting final pH (which affects the dissocn. of the SI), the Ca-SI binding, and the soly. of the resulting complex.
- 47Rietra, R. P. J. J.; Hiemstra, T.; van Riemsdijk, W. H. Interaction between Calcium and Phosphate Adsorption on Goethite. Environ. Sci. Technol. 2001, 35 (16), 3369– 3374, DOI: 10.1021/es000210bGoogle Scholar47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXkvV2qtLs%253D&md5=4f714c86a2459fc3c3e80dc588b1ab57Interaction between Calcium and Phosphate Adsorption on GoethiteRietra, Rene P. J. J.; Hiemstra, Tjisse; van Riemsdijk, Willem H.Environmental Science and Technology (2001), 35 (16), 3369-3374CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)Quant., little is known about the ion interaction processes that are responsible for the binding of phosphate in soil, water, and sediment, which det. the bioavailability and mobility of phosphate. Studies have shown that metal hydroxides are often responsible for the binding of PO43- in soils and sediments, but the binding behavior of PO43- in these systems often differs significantly from adsorption studies on metal hydroxides in lab. The interaction between PO43- and Ca adsorption was studied on goethite because Ca can influence the PO43- adsorption equil. Since adsorption interactions are very difficult to discriminate from pptn. reactions, conditions were chosen to prevent pptn. of Ca-PO43- solids. Adsorption expts. of PO43- and Ca, individually and in combination, show a strong interaction between adsorbed Ca and PO43- on goethite for conditions below the satn. index of apatite. It is shown that it is possible to predict the adsorption and interaction of PO43- and Ca on electrostatic arguments using the model parameter values derived from the single-ion systems and without invoking ternary complex formation or pptn. The model enables the prediction of the Ca-PO43- interaction for environmentally relevant calcium and phosphate concns.
- 48Karthikeyan, K. G.; Elliott, H. A.; Chorover, J. Role of Surface Precipitation in Copper Sorption by the Hydrous Oxides of Iron and Aluminum. J. Colloid Interface Sci. 1999, 209 (1), 72– 78, DOI: 10.1006/jcis.1998.5893Google Scholar48https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXjtFaqsQ%253D%253D&md5=b9e7fa0b433409b9efd425387d0c5de6Role of surface precipitation in copper sorption by the hydrous oxides of iron and aluminumKarthikeyan, K. G.; Elliott, Herschel A.; Chorover, JonJournal of Colloid and Interface Science (1999), 209 (1), 72-78CODEN: JCISA5; ISSN:0021-9797. (Academic Press)Isotherms were developed at pH 6.9 for adsorption (ADS) and copptn. (CPT) of Cu by hydrous oxides of Fe (HFO) and Al (HAO) to study the role of sorbate/sorbent ratio in metal cation removal. For low sorbate/sorbent conditions, HFO had a higher Cu retention capacity than HAO regardless of contact methodol. For either oxide, CPT was consistently more effective than ADS in removing Cu from soln. At high sorbate/sorbent ratios, surface pptn. dominates and the oxide's net cation retention capacity depends on the nature and soly. of the ppt. formed at the oxide-H2O interface. X-ray diffraction patterns and isotherms of HJAO for both ADS and CPT suggest formation of a solid soln. [e.g., CuAl2O4(s)] with dramatically lower soly. than Cu(OH)2(s) pptd. in bulk soln. In contrast, Cu pptd. on the HFO surface exhibited a soly. comparable to the bulk pptd. Cu(OH)2(s). Therefore, at high sorbate/sorbent ratios, HAO has a higher Cu apparent sorption capacity than HFO. The relative utility of these oxides as metal scavengers thus depends markedly on sorbate/sorbent conditions. (c) 1999 Academic Press.
- 49Wang, X.; Hu, Y.; Tang, Y.; Yang, P.; Feng, X.; Xu, W.; Zhu, M. Phosphate and Phytate Adsorption and Precipitation on Ferrihydrite Surfaces. Environ. Sci. Nano 2017, 4 (11), 2193– 2204, DOI: 10.1039/C7EN00705AGoogle Scholar49https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhsFKisbvP&md5=d09bafc2b85f89cff2e68f851552d950Phosphate and phytate adsorption and precipitation on ferrihydrite surfacesWang, Xiaoming; Hu, Yongfeng; Tang, Yadong; Yang, Peng; Feng, Xionghan; Xu, Wenqian; Zhu, MengqiangEnvironmental Science: Nano (2017), 4 (11), 2193-2204CODEN: ESNNA4; ISSN:2051-8161. (Royal Society of Chemistry)Phosphorus (P) sorption on mineral surfaces largely controls P mobility and bioavailability, hence its pollution potential, but the sorption speciation and mechanism remain poorly understood. We have identified and quantified the speciation of both phosphate and phytate sorbed on ferrihydrite with various P loadings at pH 3-8 using differential at. pair distribution function (d-PDF) anal., synchrotron-based X-ray diffraction (XRD), and P and Fe K-edge X-ray absorption near edge structure (XANES) and attenuated total reflectance-Fourier transform IR (ATR-FTIR) spectroscopy. With increasing P sorption loading for both phosphate and phytate, the sorption mechanism transits from bidentate-binuclear surface complexation to unidentified ternary complexation and to pptn. of amorphous FePO4 and amorphous Fe-phytate. At a given P sorption loading, phosphate ppts. more readily than phytate. Both phosphate and phytate promote ferrihydrite dissoln. with phytate more intensively, but the dissolved FeIII concn. in the bulk soln. is low because the majority of the released FeIII ppt. with the anions. Results also show that amorphous FePO4 and amorphous Fe-phytate have similar PO4 local coordination environment. These new insights into the P surface complexation and pptn., and the ligand-promoted dissoln. behavior improve our understanding of P fate in soils, aquatic environment and water treatment systems as mediated by mineral-water interfacial reactions.
- 50Li, L.; Stanforth, R. Distinguishing Adsorption and Surface Precipitation of Phosphate on Goethite (α-FeOOH). J. Colloid Interface Sci. 2000, 230 (1), 12– 21, DOI: 10.1006/jcis.2000.7072Google Scholar50https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXms1Wjtbo%253D&md5=e8edfd449ffc2aa715b4b5f9d8c25280Distinguishing adsorption and surface precipitation of phosphate on goethite (α-FeOOH)Li, Li; Stanforth, RobertJournal of Colloid and Interface Science (2000), 230 (1), 12-21CODEN: JCISA5; ISSN:0021-9797. (Academic Press)The reaction between phosphate and goethite changes from adsorption into surface pptn. with no discernible changes in the adsorption isotherm. Distinguishing the 2 processes, by plotting the loss of phosphate from soln. vs. final phosphate concn. or based on theor. calcns., is difficult. This paper presents a method for distinguishing between the 2 processes based on the change in zeta potential with increasing adsorption. During adsorption, the incoming phosphate results in a more neg. surface charge as the more acidic phosphate ion replaces a less acidic surface hydroxyl. The amt. of neg. charge imparted to the surface should vary linearly with surface coverage for adsorption. Phosphate that is bound to a surface ppt., on the other hand, imparts a much smaller neg. charge to the surface, since there is no change in the character of the surface due to the addnl. phosphate. Zeta potential measurements of phosphated goethite at varying soln. pH values and surface coverages are used to det. the transition point from adsorption to surface pptn. The transition occurs at dissolved phosphate concns. much lower than those calcd. for phosphate in equil. with goethite and iron phosphate. (c) 2000 Academic Press.
- 51Boak, L. S.; Sorbie, K. New Developments in the Analysis of Scale Inhibitors. SPE Prod. Oper. 2010, 25 (04), 533– 544, DOI: 10.2118/130401-PAGoogle Scholar51https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsFSgurzM&md5=38afe3cf64e0ec75a0184a2be7d6b863New developments in the analysis of scale inhibitorsBoak, L. S.; Sorbie, K. S.SPE Production & Operations (2010), 25 (4), 533-544CODEN: SPEPCW; ISSN:1930-1855. (Society of Petroleum Engineers)Scale inhibitors (SIs) are used to control oilfield scale formation, and the ability to analyze these species is very important such that SI concns. as low as 0.5-ppm active need to be measured accurately. If phosphorus is present in the SI mol., then inductively-coupled-plasma (ICP)-based methods may be used for anal. However, the oil industry's increasing requirement to be environmentally friendly means that polymeric "green" SIs are now being used more, which raises issues concerning detection techniques (i.e., ICP vs. wet-chem. techniques). ICP detection for SIs is generally easier, but if it cannot be used, then at least time-saving improvements to wet-chem. techniques are extremely beneficial. In this paper, anal. approaches are described that have been used recently to improve chem. SI assay, esp. at low near-threshold levels (a few ppm active of SI). Progress is reported in five areas of SI anal.:. 1. Assay of sulfonated copolymer (VS-Co) was not possible by straightforward anal. without extensive dialysis and sample prepn. However, calibrations and repeats of accuracy similar to that of the C18 were found for VS-Co using amino-Pr (NH2) cartridges and the Hyamine method. 2. The Oasis 2 × 4 method has been applied to SI anal., and this is able to assay all types of polymeric SIs in principle. This method has been used to detect a VS-Co SI in a wide variety of different brine salinities from distd. water (DW) to high-salinity formation waters (FW) (e.g., a Heron-type FW). Although achievable under these different conditions, there was a significant decrease in the absorbance signals recorded with increasing salinity that was not significantly improved by a higher-capacity sorbent cartridge. 3. Various elements have been assayed in the oil phase using the ICP method. Calibrations and accurate repeats within 5 to 10% error were achieved. After solving compatibility issues, the concn. of an oil-tolerant SI was detd. successfully using calibrations and accurate repeats over a range of 0 to 10 ppm and 0 to 2,500 ppm active SI. 4. A matrix-matching Hyamine technique has been developed that allows any chloride-ion effects on the chelating process between the Hyamine and SI to be negated, allowing accurate anal. of low-polymeric SI concns. 5. ICP and wet-chem. techniques have been able to accurately detect a P-tagged (phosphorus-tagged) copolymer-type SI. The ability to apply two independent anal. methods to a given species offers some important advantages when more than one SI is deployed in a field system. In this work, excellent correlation is obsd. between the wet-chem. and ICP assay methods for this P-tagged SI. This study updates and adds to the set of anal. methods and procedures reported for SI anal. almost 20 years ago and are described in our Flow Assurance and Scale Team (FAST) lab. procedures manual.
- 52Cooney, D. O. Adsorption Design for Wastewater Treatment; CRC Press, 1998.Google ScholarThere is no corresponding record for this reference.
- 53Xu, N.; Chen, M.; Zhou, K.; Wang, Y.; Yin, H.; Chen, Z. Retention of Phosphorus on Calcite and Dolomite: Speciation and Modeling. RSC Adv. 2014, 4 (66), 35205– 35214, DOI: 10.1039/C4RA05461JGoogle Scholar53https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtFOjtL3M&md5=6aee218d4bd9403c9ad38813654b80eaRetention of phosphorus on calcite and dolomite: speciation and modelingXu, Nan; Chen, Ming; Zhou, Kairong; Wang, Yunlong; Yin, Hongwei; Chen, ZhigangRSC Advances (2014), 4 (66), 35205-35214CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)The intensive application of phosphate fertilizers in agriculture has created an important source of diffuse phosphorus pollution. The interaction of phosphorus with carbonate minerals plays a role in the fate and transport of phosphorus in soil. The object of the present study was to investigate the speciation of phosphorus on two common carbonate minerals, calcite and dolomite, using a combination of batch expts., ATR-FTIR spectroscopy, XANES anal., and diffuse layer modeling. Within the pH range 6.0-7.0, the retention of phosphorus by calcite and dolomite is mainly attributed to the formation of amorphous calcium phosphate (Ca3(PO4)2, ACP), dibasic calcium phosphate (CaHPO4·2H2O, DCP), and hydroxyapatite (Ca5(PO4)3OH, HAP). At pH ≥ 8.0 the immobilized phosphorus takes the form of complexes =CaPO4Ca0/=sCaPO4Ca0 on the surface of calcite, followed by the formation of Ca-P phases, including ACP, DCP, and HAP, with increasing phosphorus levels (>2 mg L-1). However, the dolomite surface is initially dominated by the adsorption complex =MgHPO4Ca+ at =Mg sites, and at higher phosphorus levels it then grows due to Ca-P phases and the formation of newberyite (MgHPO4). It is interesting to note that the Mg content in dolomite favors the rapid growth of DCP at phosphorus levels >200 mg L-1. As a result, at pH ≥ 8.0, dolomite shows a stronger capacity for immobilizing phosphorus than does calcite. Dolomite therefore serves as a better phosphorus sink than calcite in calcareous soil environments.
- 54Wei, H.; Han, L.; Tang, Y.; Ren, J.; Zhao, Z.; Jia, L. Highly Flexible Heparin-Modified Chitosan/Graphene Oxide Hybrid Hydrogel as a Super Bilirubin Adsorbent with Excellent Hemocompatibility. J. Mater. Chem. B 2015, 3 (8), 1646– 1654, DOI: 10.1039/C4TB01673DGoogle Scholar54https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhs1Kqtw%253D%253D&md5=2f1745c747fb3521d7539e2712b61084Highly flexible heparin-modified chitosan/graphene oxide hybrid hydrogel as a super bilirubin adsorbent with excellent hemocompatibilityWei, Houliang; Han, Lulu; Tang, Yongchao; Ren, Jun; Zhao, Zongbin; Jia, LingyunJournal of Materials Chemistry B: Materials for Biology and Medicine (2015), 3 (8), 1646-1654CODEN: JMCBDV; ISSN:2050-7518. (Royal Society of Chemistry)As a pathogenic toxin, bilirubin is generally removed from blood by hemoperfusion for the remission of liver disease or to gain time for patients waiting for liver transplantation. However, the development of bilirubin adsorbents with excellent mech. properties, adsorption performance and hemocompatibility is still a considerable challenge. In this work, a heparin-modified chitosan/graphene oxide hybrid hydrogel (hep-CS/GH) has been developed for bilirubin adsorption using a lyophilization-neutralization-modification strategy. The as-prepd. hybrid hydrogel displayed a unique foam-like porous structure and excellent mech. flexibility. It was revealed that the incorporation of graphene oxide into the chitosan matrix enhanced both the compressive strength and the Young's modulus of the hybrid hydrogel, as well as its adsorption capacity for bilirubin. The max. adsorption capacity of hep-CS/GH for bilirubin was 92.59 mg g-1, according to the Langmuir isotherm model. It was demonstrated that hep-CS/GH successfully competed with albumin, and could effectively adsorb bilirubin from a bilirubin-enriched serum. After the hydrogel was modified with heparin, protein adsorption, platelet adhesion and hemolysis were reduced, and the plasma clotting time was prolonged from 4.1 to 23.6 min, indicating the superior hemocompatibility of hep-CS/GH. Therefore, this study may pave the way for improving the performance of the adsorbent in removing blood toxins.
- 55Spinthaki, A.; Demadis, K. D. Chemical Methods for Scaling Control. In Corrosion and Fouling Control in Desalination Industry; Springer, 2020; pp 307– 342.Google ScholarThere is no corresponding record for this reference.
- 56Shaw, S. S. Investigation into the Mechanisms of Formation and Prevention of Barium Sulphate Oilfield Scale; Heriot-Watt University, 2012.Google ScholarThere is no corresponding record for this reference.
- 57Shaw, S. S.; Sorbie, K. S. Structure, Stoichiometry, and Modeling of Calcium Phosphonate Scale-Inhibitor Complexes for Application in Precipitation-Squeeze Processes. SPE Prod. Oper. 2014, 29 (02), 139– 151, DOI: 10.2118/164051-PAGoogle Scholar57https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXptlOgsQ%253D%253D&md5=f06a5debf9e26a6d8e6337990202f748Structure, stoichiometry, and modeling of calcium phosphonate scale-inhibitor complexes for application in precipitation-squeeze processesShaw, S. S.; Sorbie, K. S.SPE Production & Operations (2014), 29 (2), 139-151, 13 pp.CODEN: SPEPCW; ISSN:1930-1863. (Society of Petroleum Engineers)Phosphonate scale inhibitors (SIs) applied in downhole-squeeze applications may be retained in the near-well formation through adsorption and/or pptn. mechanisms. In this paper, we focus on the properties of pptd. calcium phosphonate complexes formed by nine common phosphonate species. The stoichiometry [calcium ion to phosphorous (Ca2+/P) ratios] in various ppts. is established exptl., and the effect of soln. pH on the molar ratio of Ca2+/P in the ppt. is investigated. All static pptn. tests were carried out in distd. water (DW), with only Ca2+ [as calcium chloride (CaCl2)] and SI present in the system at test temps. from 20 to 95°C. The molar ratio of Ca2+/P in the solid ppt. was detd. by assaying for Ca2+ and P in the supernatant liq. under each test condition by inductively coupled plasma (ICP) spectroscopy (Ca0 and P0 are known, but are also measured exptl.). We show exptl. that the molar ratio of pptd. Ca2+/P (or Ca2+/SI; or n in the SI-Can complex) depends on the SI itself and is a function of pH for all phosphonates tested. It is found that, as pH increases, the molar ratio of Ca2+/P (n in the SI-Can) in the ppt. increases up to a theor. max., depending on the chem. structure of the phosphonate. Our findings corroborate proposed SI-metal complex-ion structures, which were presented previously in Shaw et al. (2012c), as discussed in detail in this paper. In addn., the pptn. behavior of the various compds. is modeled theor. by developing and solving a set of simplified equil. equations. We find that the pptn. behavior can be modeled, but only if a fraction (β) of "non-SI" of the initial phosphonate SI is taken into account. The quantity β can be as high as 0.2 (i.e., approx. 20% non-SI), although there is a degree of variability in this factor from product to product. However, good quant. agreement is shown comparing the predictions of the equil.-soly. model with the expt. Such models can be used directly in the modeling of field phosphonate pptn.-squeeze treatments.
- 58Silva, D. Thermodynamic Modelling of the Precipitation Chemistry of Scale Inhibitors and Divalent Cations (Ca and Mg). In Chemistry in the Oil Industry XVI: New Chemistries for Old Problems; Manchester, United Kingdom, 2019.Google ScholarThere is no corresponding record for this reference.
- 59Viveros-Ceballos, J. L.; Ordóñez, M.; Sayago, F. J.; Cativiela, C. Stereoselective Synthesis of α-Amino-C-Phosphinic Acids and Derivatives. Molecules 2016, 21 (9), 1141, DOI: 10.3390/molecules21091141Google Scholar59https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhslWnsbjL&md5=c9a5f8894ab1407b3903b19f09384aa4Stereoselective synthesis of α-amino-C-phosphinic acids and derivativesViveros-Ceballos, Jose Luis; Ordonez, Mario; Sayago, Francisco J.; Cativiela, CarlosMolecules (2016), 21 (9), 1141/1-1141/31CODEN: MOLEFW; ISSN:1420-3049. (MDPI AG)A review. α-Amino-C-phosphinic acids and derivs. are an important group of compds. of synthetic and medicinal interest and particular attention has been dedicated to their stereoselective synthesis in recent years. Among these, phosphinic pseudopeptides have acquired pharmacol. importance in influencing physiol. and pathol. processes, primarily acting as inhibitors for proteolytic enzymes where mol. stereochem. has proven to be crit. This review summarizes the latest developments in the asym. synthesis of acyclic and phospha-cyclic α-amino-C-phosphinic acids and derivs., following in the first case an order according to the strategy used, whereas for cyclic compds. the nitrogen embedding in the heterocyclic core is considered. In addn. selected examples of pharmacol. implications of title compds. are also disclosed.
- 60Valiakhmetova, A.; Sorbie, K. S.; Boak, L. S.; Shaw, S. S. Solubility and Inhibition Efficiency of Phosphonate Scale Inhibitor_calcium_magnesium Complexes for Application in a Precipitation-Squeeze Treatment. SPE Prod. Oper. 2017, 32 (03), 343– 350, DOI: 10.2118/178977-PAGoogle Scholar60https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhs1Ogu77L&md5=d2a1b1eda4638e918b716e18d55b10f7Solubility and inhibition efficiency of phosphonate scale inhibitor_calcium_magnesium complexes for application in a precipitation-squeeze treatmentValiakhmetova, A.; Sorbie, K. S.; Boak, L. S.; Shaw, S. S.SPE Production & Operations (2017), 32 (3), 343-350CODEN: SPEPCW; ISSN:1930-1863. (Society of Petroleum Engineers)Scale-inhibitor (SI) squeeze treatments are applied extensively for controlling scale formation during oil and gas prodn. The current research involves phosphonate/metal ppt. studies in the context of pptn.-squeeze treatments. The main focus here is on the pptn. and soly. behavior of the SI_ calcium (Ca)_magnesium (Mg) complexes of HEDP (a diphosphonate), DETPMP (a pentaphosphonate), and OMTHP (a hexaphosphonate); these mixed phosphonate/divalent ppts. are denoted as SI_Can1_Mgn2, where n1 and n2 are the stoichiometric ratios of Ca and Mg to SI, resp. Pptn. expts. with SI_Can1_Mgn2 species were carried out over a temp. range of 20 to 95 C, while varying the Mg/Ca molar ratio over a wide range from all Ca to all Mg. These ppts. were formed in MgCl2·6H2O/CaCl2·6H2O brine solns. with appropriate molar ratios of metals, then sepd. from the supernatant by filtration. Subsequently, the soly. of the collected ppt. was found in a soln. of the same Mg/Ca molar compn. from which it was prepd. In this type of expt., the soly. of the SI_Can1_Mgn2 ppt. without any respeciation is detd. In addn., another type of soly. expt. was carried out for a ppt. formed in a brine with one fixed Mg/Ca ratio; this was subsequently placed into a soln. with different Mg/Ca compns. (from all Ca to all Mg). In these expts., respeciation of the ppt. may occur. We have been able to establish the soly. (Cs) of the ppts. of three SIs (HEDP, OMTHP, and DETPMP) as a function of both temp. and Mg/Ca molar ratio. It has been shown that the soly. of ppt. is in equil. with Mg and Ca concns. in soln., and any change of these parameters leads to soly. variation. All phosphonate/metal ppts. become less sol. with increasing temp. and much more sol. with an increasing proportion of Mg. We have found that any change in Mg/Ca ratio of brine does lead to a redistribution of Ca, Mg, and SI concns. in a given ppt. and bulk soln., and, hence, leads to some variation in the ppt. soly. Addnl., the inhibition efficiency (IE) of pptd. and then redissolved HEDP, OMTHP, and DETPMP SIs was tested and compared with the IE of industrial stock products. We show that, unlike polymeric SI ppts., the inhibition activity of phosphonate SIs does not depend significantly on the pptn. process, and the IE of pptd. and redissolved SI_Ca and SI_Ca_Mg complexes is very close to that of the industrial stock solns. These results can be used directly for modeling phosphonate pptn.-squeeze treatments, and the significance of these results for field applications is explained.
- 61Sorbie, K. S.; Laing, N. How Scale Inhibitors Work: Mechanisms of Selected Barium Sulphate Scale Inhibitors across a Wide Temperature Range. In SPE International Symposium on Oilfield Scale; Society of Petroleum Engineers, 2004.Google ScholarThere is no corresponding record for this reference.
- 62Pourmohammadbagher, A.; Shaw, J. M. Probing Contaminant Transport to and from Clay Surfaces in Organic Solvents and Water Using Solution Calorimetry. Environ. Sci. Technol. 2015, 49 (18), 10841– 10849, DOI: 10.1021/acs.est.5b02416Google Scholar62https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlOntLfI&md5=d9897c19bfb316fb4485019b323ed639Probing Contaminant Transport to and from Clay Surfaces in Organic Solvents and Water Using Solution CalorimetryPourmohammadbagher, Amin; Shaw, John M.Environmental Science & Technology (2015), 49 (18), 10841-10849CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)Clays, in tailings, are a significant ongoing environmental concern in the mining and oilsands prodn. industries, and clay rehabilitation following contamination poses challenges episodically. Understanding the fundamentals of clay behavior can lead to better environmental impact mitigation strategies. Systematic calorimetric measurements are shown to provide a framework for parsing the synergistic and antagonistic impacts of trace (ppm level) components on the surface compns. of clays. The enthalpy of soln. of as-received and contaminated clays, in as-received and contaminated org. solvents and water, at 60° and atm. pressure, provides important illustrative examples. Clay contamination included pre-satn. of clays with water and org. liqs. Solvent contamination included the addn. of trace water to org. solvents and trace org. liqs. to water. Enthalpy of soln. outcomes are interpreted using a quant. mass and energy balance modeling framework that isolates terms for solvent and trace contaminant sorption/desorption and surface energy effects. Underlying surface energies are shown to dominate the energetics of the solvent-clay interaction, and org. liqs. as solvents or as trace contaminants are shown to displace water from as-received clay surfaces. This approach can be readily extended to include pH, salts, or other effects and is expected to provide mechanistic and quant. insights underlying the stability of clays in tailings ponds and the behaviors of clays in diverse industrial and natural environments.
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Abstract
Figure 1
Figure 1. Schematic of the three principal scale squeeze treatment stages. Reproduced with permission from ref (18). Copyright 2020 American Chemical Society.
Figure 2
Figure 2. Scheme of static adsorption and compatibility experiment.
Figure 3
Figure 3. Specifications of the scale inhibitors (SI) used in this work. Reproduced with permission from ref (45). Copyright 2020 American Chemical Society.
Figure 4
Figure 4. Morphology of pure calcite on ESEM photographed sample.
Figure 5
Figure 5. Schematic showing how both coupled adsorption and precipitation can occur showing how this could be interpreted as an “apparent adsorption”, Γap.
Figure 6
Figure 6. Apparent adsorption (Γapp vs Cf,) for DETPMP onto 2 masses (m = 5 and 10 g) of calcite for two size fractions of calcite (315–500 μm and 125–250 μm) at pH0 4 and T = 95 °C. Solid lines are matched to calculate β and n in eqs 4 and 5. Dashed lines are predicted using the model. Inset: Pure adsorption region.
Figure 7
Figure 7. Comparison of pH trend for different masses of calcite (315–500 and 125–250 μm) versus final [DETPMP]
Figure 8
Figure 8. Normalized [Ca2+] (C/C0) versus final [DETPMP] for the size fractions of 315–500 and 125–250 μm.
Figure 9
Figure 9. Morphology of samples for pure calcite, 100, 500, and 2000 ppm DETPMP for 315–500 μm calcite from ESEM photographed samples.
Figure 10
Figure 10. Particle size distribution for precipitate deposited on filter paper in different concentrations of DETPMP using 45 mm lens.
Figure 11
Figure 11. Apparent adsorption (Γapp vs Cf) for VS-Co onto 2 masses (m = 5 and 10 g) of calcite for two size fractions of calcite (315–500 μm and 125–250 μm) at natural pH and T = 95 °C. Solid lines are matched to calculate n, α, and β in eqs 1 and 2. Dashed lines are predicted using the model. Inset: Pure adsorption region.
Figure 12
Figure 12. Comparison of pH trend for different masses of calcite (315–500 and 125–250 μm) versus final concentration of VS-Co.
Figure 13
Figure 13. Normalized [Ca2+] (C/C0) vs final [VS-Co] for the size fractions of 315–500 and 125–250 μm.
Figure 14
Figure 14. Morphology of samples for (a) pure calcite, (b) 2500, (c) 1000, and (d)10 000 ppm VS-Co for 315–500 μm calcite from ESEM photographed samples.
Figure 15
Figure 15. Particle size analysis for 5 g of 125–250 μm calcite residue in different concentrations with 45 mm lens.
Figure 16
Figure 16. Schematic diagram of the mechanistic for calcite substrate, which is dissolved in seawater.
Figure 17
Figure 17. Schematic diagram of the mechanistic for DETPMP dissociation which results in adsorption of DETPMP on calcite substrate (at lower concentration, for example, [DETPMP] < 100 ppm) because of the increasing pH in seawater.
Figure 18
Figure 18. Schematic diagram of the mechanistic for DETPMP dissociation which results in adsorption/precipitation of DETPMP on calcite substrate (at higher concentration, e.g., [DETPMP] > 100 ppm) in seawater.
Figure 19
Figure 19. Schematic diagram of the mechanistic for VS-Co dissociation which results in adsorption of VS-Co on calcite substrate (at lower concentration, e.g., [VS-Co] < 3000 ppm) in seawater.
Figure 20
Figure 20. Schematic diagram of the mechanistic for VS-Co dissociation which results in adsorption/precipitation of VS-Co on calcite substrate (at higher concentration, e.g., [VS-Co] > 3000 ppm) in seawater.
References
This article references 62 other publications.
- 1Kelland, M. A. Effect of Various Cations on the Formation of Calcium Carbonate and Barium Sulfate Scale with and without Scale Inhibitors. Ind. Eng. Chem. Res. 2011, 50 (9), 5852– 5861, DOI: 10.1021/ie20034941https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXkt1Cqu7s%253D&md5=63ad2599af88ff9907a237237141dd29Effect of Various Cations on the Formation of Calcium Carbonate and Barium Sulfate Scale with and without Scale InhibitorsKelland, Malcolm A.Industrial & Engineering Chemistry Research (2011), 50 (9), 5852-5861CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)High pressure dynamic tube blocking tests have been conducted to det. the effect of iron (divalent and trivalent), calcium, magnesium, and sodium ions on the formation of calcium carbonate and barium sulfate scale with and without added scale inhibitors. Scale inhibitors were chosen to represent the three main functional groups used in com. oilfield scale inhibitors: the phosphonate group (found in sodium diethylenetriaminepentaphosphonate), the carboxylate group (in sodium polyaspartate), and the sulfonate group (in sodium polyvinysulfonate). A fourth proprietary inhibitor with phosphonate and carboxylate groups was also used in some studies.
- 2Maffra, D. A.; Freitas, T. C.; da Cruz, G. F.; de Siqueira, F. D.; do Rosário, F. F. Evaluation of Barium Sulfate Scale Inhibition Using Relative Permeability Modifier Polymers as Adsorption Enhancer for Mature Offshore Well Treatments in Campos Basin, Brazil. Ind. Eng. Chem. Res. 2018, 57 (34), 11493– 11504, DOI: 10.1021/acs.iecr.8b018282https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhsVejtr7O&md5=01950cd7a6f05a2e59725ee2eb563c48Evaluation of Barium Sulfate Scale Inhibition Using Relative Permeability Modifier Polymers as Adsorption Enhancer for Mature Offshore Well Treatments in Campos Basin, BrazilMaffra, Daniel A.; Freitas, Tiago C.; da Cruz, Georgiana F.; de Siqueira, Fernando D.; do Rosario, Francisca F.Industrial & Engineering Chemistry Research (2018), 57 (34), 11493-11504CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)In many mature offshore fields, high water cuts and potential scale deposition are some of the toughest challenges operators need to face. Two common practices used to deal with these challenges are relative permeability modifiers (RPM) polymer injection and scale inhibitor squeeze treatments. Even though many fields face these two challenges simultaneously, little is known about concomitant application of these treatments. In this paper, the effect of applying RPM polymers prior to inhibitor squeeze in the effectiveness of the last treatment is evaluated for sandstone rocks of Campos Basin, Brazil. Sequential lab. injections in Campos Basin rocks of com. cationic and anionic polyacrylamide and polyaluminum chloride (PAC) as crosslinking agent were employed prior to the injection of a com. organophosphonic acid type inhibitor for barium sulfate scale. It was found that the polymers employed are capable of reducing the permeability of porous media to water and increasing the retention time of the scale inhibitor simultaneously. The tests also indicated that the inhibitor's longer retention time is assocd. with the interaction with an outer cationic layer of the crosslinking agent. The adsorption isotherms were calcd. and compared with Langmuir, Freundlich, Sips, and Toth models, the last two being the most accurate in representing the adsorption system for these tests.
- 3He, S.; Kan, A. T.; Tomson, M. B. Mathematical Inhibitor Model for Barium Sulfate Scale Control. Langmuir 1996, 12 (7), 1901– 1905, DOI: 10.1021/la950876x3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28XhsFCjsLg%253D&md5=8e7d65bece08519c2f5e63955d47a65aMathematical Inhibitor Model for Barium Sulfate Scale ControlHe, Shiliang; Kan, Amy T.; Tomson, Mason B.Langmuir (1996), 12 (7), 1901-5CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)A semiempirical math. model has been developed to predict inhibitor efficiency for barium sulfate scale control in industrial processes. This model can be used for selecting effective inhibitors and detg. the minimal effective concn. needed for a given system. The model incorporates exptl. data of the nucleation and inhibition kinetics. Specifically, the induction period in the presence and absence of scale inhibitors has been measured exptl. and inputted into the model: Cinh = (1/b) log[tinh/t0], where Cinh is the inhibitor concn., tinh is the inhibition time (e.g., 20 min), t0 is the nucleation induction period of the scaling mineral crystal, and b is the inhibitor efficiency. The inhibition kinetics of barium sulfate nucleation with bis(hexamethylene)triaminepenta(methylenephosphonic acid) (BHMTPMP) and several other polyphosphonate and polyacrylate inhibitors have been measured. Many factors which are important to nucleation and inhibition kinetics, such as the degree of supersatn., temp., and soln. pH, have been included in the inhibitor model. The model prediction for barium sulfate scale control was in good agreement with lab. observations and field experience.
- 4Mady, M. F.; Rehman, A.; Kelland, M. A. Synthesis and Study of Modified Polyaspartic Acid Coupled Phosphonate and Sulfonate Moieties As Green Oilfield Scale Inhibitors. Ind. Eng. Chem. Res. 2021, 60, 8331, DOI: 10.1021/acs.iecr.1c014734https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXht1aktb7I&md5=c67b6758f07156be25669b521120b0cdSynthesis and study of modified polyaspartic acid coupled phosphonate and sulfonate moieties as green oilfield scale inhibitorsMady, Mohamed F.; Rehman, Abdur; Kelland, Malcolm A.Industrial & Engineering Chemistry Research (2021), 60 (23), 8331-8339CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)The petroleum industry has strived for several years to explore environmentally friendly scale inhibitors with no acute environmental impact. Well-known industrial biodegradable polyaspartic acid is widely used as a potent scale inhibitor (SI) against various inorg. scales in industrial circulating cooling water and topside petroleum applications. However, polyaspartic acid showed weak thermal stability at the petroleum reservoir temps. Here, we attempt to develop a new class of polyaspartic acid for squeeze treatment applications under harsh conditions. In this project, a series of modified polyaspartic acid, including pendant anionic functional moieties (phosphonate and sulfonate) were synthesized and investigated as new SIs to inhibit the calcium carbonate (calcite, CaCO3) and barium sulfate (barite, BaSO4) scales under oilfield conditions. These classes were synthesized via aminolysis of polysuccinimide with nucleophilic amine reagents under alk. conditions. The products are polyaspartic acid-capped aminomethylene phosphonic acid (SI-2), polyaspartic acid-capped bisphosphonic acid (SI-3), polyaspartic acid-capped aminomethanesulfonic acid (SI-4), and polyaspartic acid-capped aminoethanesulfonic acid (SI-5), as well as inhouse synthesized polyaspartic acid (SI-1). The scale inhibition activities of these compds. against carbonate and sulfate scales were detd. using the dynamic scale loop test at 100°C and 80 bar. Furthermore, the long-term thermal aging and calcium tolerance expts. were also investigated. It was found that polyaspartic-acid-capped aminomethylene phosphonic acid (SI-2) gave outstanding calcite scale inhibition performance and showed excellent thermal stability at 130°C for 7 days compared to SI-1 and other modified SIs (SI-3-SI-5). This phosphonated polymer also exhibited superior calcium tolerance performance with Ca2+ ions up to 100 ppm, and moderate performance in the range of 1000-10 000 ppm calcium ions. This project highlights the success of designing and developing a new environmentally friendly calcite SI-based polyaspartic acid under harsh oilfield conditions.
- 5Dietzsch, M.; Barz, M.; Schüler, T.; Klassen, S.; Schreiber, M.; Susewind, M.; Loges, N.; Lang, M.; Hellmann, N.; Fritz, M.; Fischer, K.; Theato, P.; Kühnle, A.; Schmidt, M.; Zentel, R.; Tremel, W. PAA-PAMPS Copolymers as an Efficient Tool to Control CaCO3 Scale Formation. Langmuir 2013, 29 (9), 3080– 3088, DOI: 10.1021/la40000445https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXitFajsbo%253D&md5=fb1893a70f6ffbed2b41d6bb68ab297aPAA-PAMPS Copolymers as an Efficient Tool to Control CaCO3 Scale FormationDietzsch, Michael; Barz, Matthias; Schueler, Timo; Klassen, Stefanie; Schreiber, Martin; Susewind, Moritz; Loges, Niklas; Lang, Michael; Hellmann, Nadja; Fritz, Monika; Fischer, Karl; Theato, Patrick; Kuehnle, Angelika; Schmidt, Manfred; Zentel, Rudolf; Tremel, WolfgangLangmuir (2013), 29 (9), 3080-3088CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Scale formation, the deposition of certain minerals such as CaCO3, MgCO3, and CaSO4·2H2O in industrial facilities and household devices, leads to reduced efficiency or severe damage. Therefore, incrustation is a major problem in everyday life. In recent years, double hydrophilic block copolymers (DHBCs) have been the focus of interest in academia with regard to their antiscaling potential. In this work, we synthesized well-defined blocklike PAA-PAMPS copolymers consisting of acrylic acid (AA) and 2-acrylamido-2-methyl-propane sulfonate (AMPS) units in a one-step reaction by RAFT polymn. The derived copolymers had dispersities of 1.3 and below. The copolymers have then been investigated in detail regarding their impact on the different stages of the crystn. process of CaCO3. Ca2+ complexation, the first step of a pptn. process, and polyelectrolyte stability in aq. soln. have been investigated by potentiometric measurements, isothermal titrn. calorimetry (ITC), and dynamic light scattering (DLS). A weak Ca2+ induced copolymer aggregation without concomitant pptn. was obsd. Nucleation, early particle growth, and colloidal stability have been monitored in situ with DLS. The copolymers retard or even completely suppress nucleation, most probably by complexation of soln. aggregates. In addn., they stabilize existing CaCO3 particles in the nanometer regime. In situ AFM was used as a tool to verify the coordination of the copolymer to the calcite (104) crystal surface and to est. its potential as a growth inhibitor in a supersatd. CaCO3 environment. All investigated copolymers instantly stopped further crystal growth. The carboxylate richest copolymer as the most promising antiscaling candidate proved its enormous potential in scale inhibition as well in an industrial-filming test (Fresenius std. method).
- 6Mirzaalian Dastjerdi, A.; Kargozarfard, Z.; Najafi, B.; Taghikhani, V.; Ayatollahi, S. A Microscopic Insight into Kinetics of Inorganic Scale Deposition during Smart Water Injection Using Dynamic Quartz Crystal Microbalance and Molecular Dynamics Simulation. Ind. Eng. Chem. Res. 2020, 59, 609, DOI: 10.1021/acs.iecr.9b052366https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisVektrjP&md5=9a2cfc2d6055a4ba137c6f13cd33cba2Microscopic Insight into Kinetics of Inorganic Scale Deposition during Smart Water Injection Using Dynamic Quartz Crystal Microbalance and Molecular Dynamics SimulationMirzaalian Dastjerdi, Ali; Kargozarfard, Zahra; Najafi, Bita; Taghikhani, Vahid; Ayatollahi, ShahabIndustrial & Engineering Chemistry Research (2020), 59 (2), 609-619CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Inorg. scale deposition has been found to affect many industrial processes, including water injection into the oil reservoirs. The incompatibility of high sulfate ion content of seawater with formation water contg. calcium ions results in formation damage and prodn. decline. In this study, several simultaneous techniques are utilized for qual. and quant. analyses of calcium sulfate scale to get more insight into the formation damage during smart water flooding at micro and nanoscales. In the exptl. section, calcium sulfate deposition due to the mixing of the formation water and seawater samples was investigated using the dynamic quartz crystal microbalance technique. The effect of sulfate and magnesium ions existing in the seawater on the amt. of calcium sulfate deposition was studied, individually. The results showed that the sulfate concn. of seawater could significantly change the mass deposition in a specific range. Also, at an optimal concn. of the magnesium ions, the total amt. of calcium sulfate deposition decreased by 60%. However, magnesium ions could decrease the time of the initial stage of deposition significantly. The results revealed the amt. of deposition and the time of initial stage beyond 5 times diln. of seawater are not noticeable. In addn., the linear slope of the second stage of deposition for the mixt. of formation water and 5-fold dild. seawater decreased by 92% compared to the original seawater. To verify the results for the magnesium effect, the mol. dynamics simulation method was used to compare the simulation results with the exptl. data. Likewise, the results obtained from the simulation model showed that at an optimal concn. of the magnesium ions in the seawater, the amt. of calcium sulfate deposition was noticeably decreased.
- 7Chao, Y.; Horner, O.; Vallée, P.; Meneau, F.; Alos-Ramos, O.; Hui, F.; Turmine, M.; Perrot, H.; Lédion, J. In Situ Probing Calcium Carbonate Formation by Combining Fast Controlled Precipitation Method and Small-Angle X-Ray Scattering. Langmuir 2014, 30 (12), 3303– 3309, DOI: 10.1021/la500202g7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXjtV2qtbg%253D&md5=8e45e03db990c59a6b578f409e7bfc76In Situ Probing Calcium Carbonate Formation by Combining Fast Controlled Precipitation Method and Small-Angle X-ray ScatteringChao, Yanjia; Horner, Olivier; Vallee, Philippe; Meneau, Florian; Alos-Ramos, Olga; Hui, Franck; Turmine, Mireille; Perrot, Hubert; Ledion, JeanLangmuir (2014), 30 (12), 3303-3309CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)The initial stage of calcium carbonate nucleation and growth, found usually in "natural" pptn. conditions, is still not well understood. The calcium carbonate formation for moderate supersatn. level could be achieved by an original method called the fast controlled pptn. (FCP) method. FCP was coupled with SAXS (small-angle X-ray scattering) measurements to get insight into the nucleation and growth mechanisms of calcium carbonate particles in Ca(HCO3)2 aq. solns. Two size distributions of particles were obsd. The particle size evolutions of these two distributions were obtained by analyzing the SAXS data. A nice agreement was obtained between the total vol. fractions of CaCO3 obtained by SAXS anal. and by pH-resistivity curve modeling (from FCP tests).
- 8Hasson, D.; Shemer, H.; Sher, A. State of the Art of Friendly “Green” Scale Control Inhibitors: A Review Article. Ind. Eng. Chem. Res. 2011, 50 (12), 7601– 7607, DOI: 10.1021/ie200370v8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXmsVWls7s%253D&md5=cfa952d7743338a6b1f94beb4bd86c94State of the Art of Friendly "Green" Scale Control Inhibitors: A Review ArticleHasson, David; Shemer, Hilla; Sher, AlexanderIndustrial & Engineering Chemistry Research (2011), 50 (12), 7601-7607CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)A review is given. Scale deposition is a difficulty encountered with water contg. ions of sparingly sol. salts. A widely used technique for controlling scale deposition is by dosage of an antiscalant. Large quantities of polymeric scale inhibitors are used for scale control in cooling water systems, water desalination processes, and oil field operations. Like most conventional polymers, scale inhibitors are built for long existence and persist for many years after their disposal. Increasing environmental concern and discharge limitations have caused scale-inhibitor chem. to move toward green antiscalants that readily biodegrade, have low mobility for min. environmental impact, and are cost-effective. This review summarizes efforts to develop cost-effective ecol. benign scale inhibitors. Currently, the most promising green scale inhibitors are based on poly(aspartic acid). However, field operation data are very limited, and widespread use of poly(aspartic acid) scale inhibitors awaits field operation experience.
- 9Baraka-Lokmane, S.; Sorbie, K. S. Effect of PH and Scale Inhibitor Concentration on Phosphonate–Carbonate Interaction. J. Pet. Sci. Eng. 2010, 70 (1–2), 10– 27, DOI: 10.1016/j.petrol.2009.05.0029https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsF2isrzJ&md5=ccef234bfbffbcf7d5218ca9374cb315Effect of pH and scale inhibitor concentration on phosphonate-carbonate interactionBaraka-Lokmane, S.; Sorbie, K. S.Journal of Petroleum Science & Engineering (2010), 70 (1-2), 10-27CODEN: JPSEE6; ISSN:0920-4105. (Elsevier B.V.)In this paper, we present results from five corefloods (RC1 to RC5) from the Jurassic Portlandian limestone (Φ ∼ 19.80% and k = 606 mD) using 5000 ppm, 10,000 ppm, 25,000 ppm and 27,000 ppm of partly neutralized Diethylenetriamine pentamethylenephosphoric acid (DETPMP) at pH 4 and 2. The purpose of this study was to study the effect of inhibitor concn. and pH on the inhibitor adsorption and on the evolution of the inhibitor and cation (calcium and magnesium) return concns. These corefloods were performed using long cores (12 in.), which were treated with just 0.5 pore vol. (PV) of inhibitor. Another purpose was to study the transport and inhibitor/carbonate rock interactions when less than 1 PV of inhibitor soln. is injected. This allows for consumption of the inhibitor during propagation and return, rather than satg. the core with many PV to full adsorptive capacity of the inhibitor/rock system. This study showed that the higher the concn. of SI and lower the pH, the more calcium dissoln. is obsd. (from the [Ca2+] effluents). In all treatments there is a decrease in the [Mg2+] effluent corresponding directly to the increase in calcium. The effluent cation results in the long corefloods which strongly support the view that both magnesium and calcium are binding quite strongly to the DETPMP scale inhibitor. These observations lead us to a no. of conclusions on the factors that must be included in a full carbonate model. In particular, our exptl. results, along with some simple modeling, greatly clarify the role of both calcium and magnesium in the mechanism of the scale inhibitor retention in carbonate systems.
- 10Khormali, A.; Petrakov, D. G.; Nazari Moghaddam, R. Study of Adsorption/Desorption Properties of a New Scale Inhibitor Package to Prevent Calcium Carbonate Formation during Water Injection in Oil Reservoirs. J. Pet. Sci. Eng. 2017, 153, 257– 267, DOI: 10.1016/j.petrol.2017.04.00810https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXlvFynuro%253D&md5=f16d6dc6430615ef37974770393424a6Study of adsorption/desorption properties of a new scale inhibitor package to prevent calcium carbonate formation during water injection in oil reservoirsKhormali, Azizollah; Petrakov, Dmitry G.; Nazari Moghaddam, RasoulJournal of Petroleum Science & Engineering (2017), 153 (), 257-267CODEN: JPSEE6; ISSN:0920-4105. (Elsevier B.V.)Injection of an aq. soln. of scale inhibitor during the water flooding is the primary method to prevent inorg. salt formation. Adsorption/desorption abilities of scale inhibitors are key factors that influence the success of the scale inhibitor squeeze treatments. In this work, the performance of a new developed scale inhibitor has been evaluated to prevent calcium carbonate pptn. under static and dynamic conditions. Prior to any core flooding expts., satn. index of calcium carbonate and the amt. of its pptn. were studied at different mixing ratios of the synthetic injection and formation waters at different temps. Then, effectiveness of the scale inhibitor package and its min. concn. were detd. During the core flooding expts., adsorption characteristics of the scale inhibitor package were investigated using carbonate, quartz sand and quartz glass core samples. For each test, the inhibitor soln. was injected into the core samples and its concn. was measured before and after passing through the core samples. Moreover, specific adsorption of the scale inhibitor package was detd. at different injection rates. For the carbonate samples, adsorption equil. of the scale inhibitor package occurred in the lower pore vols. injected. Furthermore, improvement in the adsorption ability of the scale inhibitor package occurred due to the presence of various chem. reagents in the compn. of the scale inhibitor package. In this study, desorption process has been also studied on carbonate rocks. The results showed that the best performance of desorption process was obtained when the concn. of hydrochloric acid was 10% in the developed scale inhibitor package. In addn., redn. in dynamic viscosity of oil was obsd. in the presence of the scale inhibitor package. Interfacial tension on the boundary of oil and the aq. soln. of the scale inhibitor package was significantly reduced by an increase in the concns. of polyethylene polyamine-N-methylphosphonic acid (PPNMP) and hydrochloric acid as the components of the inhibitor package.
- 11Liu, C.; Zeng, X.; Yan, C.; Zhou, C.; Li, M.; Wang, Z. Effects of Solid Precipitation and Surface Corrosion on the Adhesion Strengths of Sintered Hydrate Deposits on Pipe Walls. Langmuir 2020, 36, 15343, DOI: 10.1021/acs.langmuir.0c0281811https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisFCrtLzJ&md5=34e32677e513ba3e2cbefcdd8b4ea9ccEffects of Solid Precipitation and Surface Corrosion on the Adhesion Strengths of Sintered Hydrate Deposits on Pipe WallsLiu, Chenwei; Zeng, Xu; Yan, Ci; Zhou, Chenru; Li, Mingzhong; Wang, ZhiyuanLangmuir (2020), 36 (50), 15343-15351CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)A hydrate directly growing and sintering on a pipe wall is an important hydrate deposition case that has been relatively unexplored. In the present study, the adhesion strengths of a sintered cyclopentane (CyC5) hydrate deposit under different solid pptn. and surface corrosion conditions were measured and discussed. It was found that the hydrate adhesion strengths increased by 1.2-1.5x when the soaking time of the carbon steel substrate in a 5 wt % NaCl soln. increased from 24 to 72 h, which reduced the water wetting angle from 112 ± 3.5° to 94 ± 3.3°. The wax coating reduced the strength of CyC5 hydrate adhesion by up to nearly 20-fold by reversing the substrate wettability and affecting the hydrate morphol. The measurements performed on scales indicate that calcium carbonate scales strengthen the adhesion strength because of the decrease in the water wetting angle. In addn., honeycomb holes on the surface reduce amplification. Furthermore, settling quartz sand on the wall reduced the adhesion strengths by decreasing the effective sintering area of the hydrate on the underlying base. Finer sand and higher concns. led to lower strengths. On the basis of the verified linear correlation between the hydrate adhesion strength and the adhesion work of droplets on different substrates and the influence of water conversion during deposition, both an equation and a key const. parameter were obtained to predict the sintered hydrate deposit adhesion strengths on substrates.
- 12Heath, S. M.; Juliussen, B.; Chen, P.; Chen, T.; Benvie, R. Novel Scale Squeeze Technology and Treatment Designs for Improving Scale Inhibitor Retention and Treatment Lifetimes-Use of Ionic Polymers in the Overflush. In SPE International Conference on Oilfield Scale; Society of Petroleum Engineers, 2012.There is no corresponding record for this reference.
- 13Jordan, M. M.; Mackay, E. J.; Vazquez, O. The Influence Of Overflush Fluid Type On Scale Squeeze Life Time-Field Examples And Placement Simulation Evaluation. In CORROSION 2008; NACE International, 2008.There is no corresponding record for this reference.
- 14Zhang, P.; Liu, Y.; Kan, A. T.; Tomson, M. B. Laboratory Evaluation of Synergistic Effect of Transition Metals with Mineral Scale Inhibitor in Controlling Halite Scale Deposition. J. Pet. Sci. Eng. 2019, 175, 120– 128, DOI: 10.1016/j.petrol.2018.12.03614https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisFGhsrjE&md5=d7720a60c9fc49346acf1f05aa0b2617Laboratory evaluation of synergistic effect of transition metals with mineral scale inhibitor in controlling halite scale depositionZhang, Ping; Liu, Yuan; Kan, Amy T.; Tomson, Mason B.Journal of Petroleum Science & Engineering (2019), 175 (), 120-128CODEN: JPSEE6; ISSN:0920-4105. (Elsevier B.V.)Sodium chloride (halite) has been traditionally regarded as an unconventional oilfield mineral scale, compared with more prevalent carbonate and sulfate scales. However, with the increasing productions from offshore deepwater and shale gas fields, halite scale occurrence becomes more frequent, leading to significant tech. and financial challenges to productions. Although low-salinity water diln. remains the primary approach in controlling halite scale threat, chem. inhibition has been evaluated as an alternative halite control strategy due to the intrinsic issues assocd. with low-salinity water availability and water quality. There are limited studies concerning the combined effect of metals, esp. transition metals with scale inhibitors in halite control. In this study, the combined effect of a no. of transition metal ions with two common halite scale inhibitors was evaluated in a lab. setup. It was found that among the transition metals studied, Pb2+ ion demonstrates a synergistic effect with the scale inhibitors evaluated by considerably extending the halite induction time. The calcd. inhibition efficiency also indicates that the presence of Pb2+ improves inhibitor performance. Although Pb2+ is an environmental pollutant, an aq. Pb2+ concn. of up to 10 mg L-1 can naturally occur in both natural gas produced water and oilfield produced water. The operators can take advantage of the reported synergistic effect of Pb2+ with scale inhibitors in this study while designing field halite control strategy. The enhanced inhibition efficiency elaborated in this study can be useful in designing the halite scale control strategy, if a decent amt. of Pb2+ is present in the produced water.
- 15Zhang, P.; Liu, Y.; Zhang, N.; Ip, W. F.; Kan, A. T.; Tomson, M. B. A Novel Attach-and-Release Mineral Scale Control Strategy: Laboratory Investigation of Retention and Release of Scale Inhibitor on Pipe Surface. J. Ind. Eng. Chem. 2019, 70, 462– 471, DOI: 10.1016/j.jiec.2018.11.00915https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXit1yls7jK&md5=1b448fa82c64ee2dd12232e67d7dfc49A novel attach-and-release mineral scale control strategy: Laboratory investigation of retention and release of scale inhibitor on pipe surfaceZhang, Ping; Liu, Yuan; Zhang, Nan; Ip, Weng Fai; Kan, Amy T.; Tomson, Mason B.Journal of Industrial and Engineering Chemistry (Amsterdam, Netherlands) (2019), 70 (), 462-471CODEN: JIECFI; ISSN:1226-086X. (Elsevier B.V.)A novel "attach-and-release" approach has been exptl. evaluated as an alternative scale control strategy for pipe flow system. Phosphonate scale inhibitor was initially attached to calcium carbonate medium on the surface of the pipe. Subsequently, the retained inhibitor was released into the flowing fluid for scale control. A plug-flow tube reactor app. was adopted in lab. studies. It shows that formation of calcium-inhibitor ppt. accounts for the attachment of inhibitor and brine chem. can considerably impact the amt. of inhibitor retained. This proposed strategy has the potential to be applied in a pipe flow system to control scale deposition threat.
- 16Yan, F.; Zhang, F.; Bhandari, N.; Wang, L.; Dai, Z.; Zhang, Z.; Liu, Y.; Ruan, G.; Kan, A.; Tomson, M. Adsorption and Precipitation of Scale Inhibitors on Shale Formations. J. Pet. Sci. Eng. 2015, 136, 32– 40, DOI: 10.1016/j.petrol.2015.11.00116https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhslyrtb7N&md5=795d474452e744700c12e8bc389150e8Adsorption and precipitation of scale inhibitors on shale formationsYan, Fei; Zhang, Fangfu; Bhandari, Narayan; Wang, Lu; Dai, Zhaoyi; Zhang, Zhang; Liu, Ya; Ruan, Gedeng; Kan, Amy; Tomson, MasonJournal of Petroleum Science & Engineering (2015), 136 (), 32-40CODEN: JPSEE6; ISSN:0920-4105. (Elsevier B.V.)Scale inhibitor is one of the most important ingredients in hydraulic fracturing fluids for shale gas prodn. However, the adsorption and pptn. behaviors of scale inhibitors on shale formations have never been reported. The objective of this study is to develop mechanistic understanding of interactions between common scale inhibitors and shale formations so that we can predict the fate and transport of scale inhibitors in shale formations. The adsorption and pptn. of DTPMP and PPCA on Eagle Ford and Marcellus shales were studied in batch reactors at oil field temp. of 70 °C. The adsorption kinetics shows a fast adsorption process of inhibitors on shales, and inhibitor concns. reach equil. between 4 and 8 h. In batch adsorption isotherm expts., initial concns. of scale inhibitors in aq. phase varied from 5 ppm to 44,000 ppm. At low DTPMP concn. ranges, surface adsorption occurs on both Eagle Ford and Marcellus. Above certain concns., DTPMP and calcium forms ppt. on Eagle Ford, which increases the attachment, and slightly acidic pH and high calcium concns. enhance the pptn. The adsorption of PPCA on Eagle Ford was more significant at slightly acidic conditions, and PPCA adsorption onto Marcellus did not exhibit a notable difference between different pH conditions. Due to the strong chelating effect of DTPMP and PPCA, iron was extd. from Marcellus under high inhibitor concns.
- 17Pairat, R.; Sumeath, C.; Browning, F. H.; Fogler, H. S. Precipitation and Dissolution of Calcium– ATMP Precipitates for the Inhibition of Scale Formation in Porous Media. Langmuir 1997, 13 (6), 1791– 1798, DOI: 10.1021/la960842517https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXhvFGgsLc%253D&md5=e622c2c731c021e748d44fb5af46c3b7Precipitation and Dissolution of Calcium-ATMP Precipitates for the Inhibition of Scale Formation in Porous MediaPairat, R.; Sumeath, C.; Browning, F. Henry; Fogler, H. ScottLangmuir (1997), 13 (6), 1791-1798CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)The pptn. reaction between aminotris(methylenephosphonic acid) (ATMP) and calcium was systematically studied in an effort to design scale control systems, esp. in petroleum recovery. By varying the pptg. conditions, three distinct ppts. formed: (1) a cryst., sheetlike, 1:1 calcium-ATMP ppt., (2) an amorphous, spherical-shaped, 2:1 calcium-ATMP ppt., and (3) an amorphous, spherical-shaped, 3:1 calcium-ATMP ppt. Corresponding batch dissoln. expts. showed that as the ppt. calcium-ATMP molar ratio increased from 1:1 to 2:1 to 3:1, the rate of dissoln. and the equil. soly. limit decreased significantly. The significance of these observations was evident when the release characteristics of each ppt. from porous media were studied as related to ATMP use in petroleum-recovery systems. The 3:1 calcium-ATMP ppt. was released from porous media in a much slower manner than the other two ppts., strongly suggesting that the 3:1 ppt. is most suitable for use in petroleum recovery.
- 18Jarrahian, K.; Sorbie, K. S. Mechanistic Investigation of Adsorption Behaviour of Two Scale Inhibitors on Carbonate Formations for Application in Squeeze Treatments. Energy Fuels 2020, 34, 4484, DOI: 10.1021/acs.energyfuels.0c0032618https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXksVGmu7s%253D&md5=5e969d629fbea5f8347d2c9444571f23Mechanistic Investigation of Adsorption Behavior of Two Scale Inhibitors on Carbonate Formations for Application in Squeeze TreatmentsJarrahian, Khosro; Sorbie, Ken. S.Energy & Fuels (2020), 34 (4), 4484-4496CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Understanding the mechanisms of scale inhibitor (SI) retention in carbonate formations is key to designing efficient SI "squeeze" treatments in oil reservoirs. By performing "apparent adsorption" expts., this paper demonstrates that a coupled adsorption/pptn. (Γ/Π) retention mechanism dominates in calcite and limestone for two widely applied scale inhibitors, DETPMP and PPCA. Pptn. was a more dominant retention mechanism at both initial pH values (pH0 4 and 6) and T = 80 and 95°C for both SIs. At 95°C, the pure adsorption (Γ) region only extends up to [SI] ~ 100 ppm, above which pptn. (Π) dominates. At lower temps. (T = 80°C), the soly. of the SI-M2+ complex increases, resulting in less pptn. The apparent adsorption results are supplemented by measuring the corresponding soln. [Ca2+], pH values in soln., and environmental SEM/energy dispersive X-ray anal. (ESEM/EDX) and particle size anal. (PSA), which give us a full mechanistic explanation of our results. For DETPMP, the retention increased as the soln. pH increased, while retention of PPCA increased as the test pH decreased. Moreover, DETPMP was retained more than PPCA due to their differences in chem. Furthermore, the retention of both SIs was greater for the limestone sample due to Fe2+ traces enhancing the ppt. of SI-M2+.
- 19Patterson, D.; Kendrick, M.; Williams, W.; Jordan, M. M. Squimulation”--Simultaneous Well-Stimulation and Scale-Squeeze Treatments in Deepwater West Africa. SPE Prod. Oper. 2013, 28 (01), 55– 66, DOI: 10.2118/151863-PA19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXksVGrsbY%253D&md5=ef72ff1c0e21f37549ec9ae948d2fc4e"Squimulation"-simultaneous well-stimulation and scale-squeeze treatments in deepwater west AfricaPatterson, D.; Kendrick, M.; Williams, W.; Jordan, M.SPE Production & Operations (2013), 28 (1), 55-66CODEN: SPEPCW; ISSN:1930-1855. (Society of Petroleum Engineers)In a deepwater west African field, the relatively small no. of high-cost, highly productive wells, coupled with a high barium sulfate scaling tendency (upon waterflood breakthrough of injected seawater) requires effective scale management along with removal of near-wellbore damage in order to achieve high hydrocarbon recovery. The nature of the well-completion strategy in the field (frac packs for sand control) had resulted in some wells with higher than expected skin values owing to drilling-fluid losses, residual fracture gel, fluid loss agents, and fines mobilization within the frac packs. The paper will present how the challenges of managing impaired completions and inorg. scale forced innovation in terms of when to apply both stimulation and scale-inhibitor packages to deepwater wells. This paper will outline a novel process for non-conventional batch chem. applications where bullhead stimulation treatments have been displaced deep into the formation (>20 ft) using a scale inhibitor overflush. Not only does this benefit the stimulation by displacing the spent acid and reagents away from the immediate wellbore area, but the combined treatment provides a cost savings with a single mobilization for the combined treatment. The paper will describe the lab. testing that was performed to qualify the treatments. The four field treatments that were performed demonstrate how these coupled applications have proven very effective at both well stimulation/skin redn. and scale-inhibitor placement before and after seawater breakthrough. The term "squimulation" is used by the local operations team to describe this simultaneous squeeze-and-stimulation process. Many similar fields are currently being developed in the Campos basin (Gulf of Mexico) and west Africa, and this paper presents a good example of best-practice sharing from another oil basin.
- 20Paukert Vankeuren, A. N.; Hakala, J. A.; Jarvis, K.; Moore, J. E. Mineral Reactions in Shale Gas Reservoirs: Barite Scale Formation from Reusing Produced Water as Hydraulic Fracturing Fluid. Environ. Sci. Technol. 2017, 51 (16), 9391– 9402, DOI: 10.1021/acs.est.7b0197920https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtF2it77L&md5=d3eb1fc4714d9eb87b71221214788bc0Mineral Reactions in Shale Gas Reservoirs: Barite Scale Formation from Reusing Produced Water As Hydraulic Fracturing FluidPaukert Vankeuren, Amelia N.; Hakala, J. Alexandra; Jarvis, Karl; Moore, Johnathan E.Environmental Science & Technology (2017), 51 (16), 9391-9402CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)Hydraulic fracturing for gas prodn. is now ubiquitous in shale plays, but relatively little is known about shale-hydraulic fracturing fluid (HFF) reactions within the reservoir. To investigate reactions during the shut-in period of hydraulic fracturing, expts. were conducted flowing different HFFs through fractured Marcellus shale cores at reservoir temp. and pressure (66 °C, 20 MPa) for one week. Results indicate HFFs with hydrochloric acid cause substantial dissoln. of carbonate minerals, as expected, increasing effective fracture vol. (fracture vol. + near-fracture matrix porosity) by 56-65%. HFFs with reused produced water compn. cause pptn. of secondary minerals, particularly barite, decreasing effective fracture vol. by 1-3%. Barite pptn. occurs despite the presence of antiscalants in expts. with and without shale contact and is driven in part by addn. of dissolved sulfate from the decompn. of persulfate breakers in HFF at reservoir conditions. The overall effect of mineral changes on the reservoir has yet to be quantified, but the significant amt. of barite scale formed by HFFs with reused produced water compn. could reduce effective fracture vol. Further study is required to extrapolate exptl. results to reservoir-scale and to explore the effect that mineral changes from HFF interaction with shale might have on gas prodn.
- 21Kan, A. T.; Fu, G.; Tomson, M. B.; Al-Thubaiti, M.; Xiao, A. J. Factors Affecting Scale Inhibitor Retention in Carbonate-Rich Formation during Squeeze Treatment. Spe J. 2004, 9 (03), 280– 289, DOI: 10.2118/80230-PA21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXovFWmtbs%253D&md5=7217bd3b2c9873218e2e2126be306c7fFactors affecting scale inhibitor retention in carbonate-rich formation during squeeze treatmentKan, Amy T.; Fu, Gongmin; Tomson, Mason B.; Al-Thubaiti, Musaed; Xiao, Alan J.SPE Journal (Society of Petroleum Engineers) (2004), 9 (3), 280-289CODEN: SPJRFW; ISSN:1086-055X. (Society of Petroleum Engineers Inc.)Significant progress has been made toward developing a quant. understanding of the inhibitor/rock interaction. In this study, four common oil field inhibitors (three phosphonates and one polyacrylate) are compared using carbonate-rich formation rocks. In addn. to calcite (CaCO3) in the reservoir rock, several calcium inhibitor (Inh) solid phases are also important. Two reactions are central to the inhibitor retention in carbonate-rich formation: first, redn. of calcite dissoln. because of surface poisoning by the Ca-Inh coating; and second, pptn. of Ca-Inh solid with either low Ca or high Ca stoichiometry. For aminotri(methylene phosphonic acid) (NTMP), an acidic Ca-NTMP salt is formed at a low-pH environment. In addn., two cryst. Ca-NTMP phases and an amorphous Ca-NTMP salt may form, depending on the aquatic environment. Quant. relationships between types of inhibitors, inhibitor acidity and concn., and kinetics of calcite dissoln. and calcium-phosphonate pptn. are developed. Consequences of the observations on squeeze design and scale inhibition are discussed.
- 22Vazquez, O.; Fursov, I.; Mackay, E. Automatic Optimization of Oilfield Scale Inhibitor Squeeze Treatment Designs. J. Pet. Sci. Eng. 2016, 147, 302– 307, DOI: 10.1016/j.petrol.2016.06.02522https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtVGmt7vE&md5=872cfa2be7a0996a46210651c9dd0d2dAutomatic optimization of oilfield scale inhibitor squeeze treatment designsVazquez, Oscar; Fursov, Ilya; Mackay, EricJournal of Petroleum Science & Engineering (2016), 147 (), 302-307CODEN: JPSEE6; ISSN:0920-4105. (Elsevier B.V.)Squeeze treatments are one of the most common methods to prevent oilfield scale deposition, which in turn is one of the most significant flow assurance challenges in the oil industry. Squeeze treatments consist of the batch injection of a chem. scale inhibitor (SI), which above a certain concn., commonly known as MIC (Min. Inhibitor Concn.), prevents scale deposition. The most important factor in a squeeze treatment design is the squeeze lifetime, which is detd. by the vol. of water or days of prodn. where the chem. return concn. is above MIC, which commonly is between 1 and 20 ppm. Typically, squeeze treatment designs include the following four stages: a preflush, acting as a buffer; the main slug, where the main chem. slug is injected; the overflush, which will displaced the chem. pill deeper into the formation and finally, a shut-in stage, which allows the chem. to be further retained in the formation. The main purpose of this paper is to describe the automatic optimization of squeeze treatment designs using an optimization algorithm, in particular, using particle swarm optimization (PSO). The algorithm provides the optimum design for a given set of criteria that are used in a purpose built reactive transport model of the near-wellbore area. Every squeeze design is fully detd. by a no. of parameters; namely, injected inhibitor concn., main slug vol., overflush vol. and shut-in time. The parameter space is bound to certain limits, which will be detd. by the max. injected concn., main slug and overflush vols. The max. injected concn. might be detd. by, amongst other issues, logistics, economics and/or compatibility with other chems. The main slug and overflush max. vols. may be identified by the well engineer based on concerns of water formation damage, hydrate formation and/or gas lifting limitations, which might be lower for high value wells. This approach still requires engineering input and review, but speeds up the process of finding an optimum design, and reduces risk of non-optimal squeeze treatments being performed.
- 23Kahrwad, M.; Sorbie, K. S.; Boak, L. S. Coupled Adsorption/Precipitation of Scale Inhibitors: Experimental Results and Modeling. SPE Prod. Oper. 2009, 24 (03), 481– 491, DOI: 10.2118/114108-PA23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtFags7zM&md5=a31ea52067661556f548866892c1e37bCoupled adsorption/precipitation of scale inhibitors: experimental results and modelingKahrwad, M.; Sorbie, K. S.; Boak, L. S.SPE Production & Operations (2009), 24 (3), 481-491CODEN: SPEPCW; ISSN:1930-1855. (Society of Petroleum Engineers)In this paper, results are presented on the general mechanisms by which scale inhibitors (SIs) are retained within porous media. There is a generally accepted view that the main two mechanisms of SI retention are "adsorption" and "pptn.," and these are described by different but related modeling approaches in the literature. These approaches have been used quite successfully to model field squeeze treatments. To analyze in a detailed and unambiguous manner where a given retention mechanism (e.g., pure adsorption) or mechanisms (e.g., coupled adsorption and pptn.) are operating requires that we carry out careful lab. expts. under "field relevant" conditions. In this work, we study adsorption vs. adsorption/pptn. by performing a series of expts. where we know that the system exhibits either (a) adsorption only or (b) coupled adsorption/pptn. Exptl., it is straightforward to det. which regime the system is in. We present the theory describing the coupled adsorption/pptn. process. In addn., an extensive series of exptl. adsorption/pptn. measurements is presented for various mineral separates including sand, chlorite, siderite, muscovite, kaolinite, and feldspar. The coupled adsorption/pptn. model is in very good agreement with the expt.
- 24Park, W. K.; Ko, S.-J.; Lee, S. W.; Cho, K.-H.; Ahn, J.-W.; Han, C. Effects of Magnesium Chloride and Organic Additives on the Synthesis of Aragonite Precipitated Calcium Carbonate. J. Cryst. Growth 2008, 310 (10), 2593– 2601, DOI: 10.1016/j.jcrysgro.2008.01.02324https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXls1Sku70%253D&md5=c2866c8cf6005d37f09755f3c434be3cEffects of magnesium chloride and organic additives on the synthesis of aragonite precipitated calcium carbonatePark, Woon Kyoung; Ko, Sang-Jin; Lee, Seung Woo; Cho, Kye-Hong; Ahn, Ji-Whan; Han, ChoonJournal of Crystal Growth (2008), 310 (10), 2593-2601CODEN: JCRGAE; ISSN:0022-0248. (Elsevier B.V.)The synthesis of aragonite pptd. calcium carbonate by treating a suspension of Ca(OH)2 with CO2 gas was investigated with regard to the effects of Mg2+ ions and org. additives on polymorphism and alternative orientations. In the presence of a small amt. of Mg2+, Mg-calcite formed, but as the Mg2+ ion concn. increased, the amt. of Mg-calcite decreased and the amt. of aragonite increased. Thus, the formation of Mg-calcite is suppressed and only aragonite is formed in the presence of 60 mol% MgCl2. As the Mg2+ ion concn. increased, the aragonite that formed was found to have decreased in terms of its longitude and aspect ratio. Furthermore, the effect of Mg2+ ions in conjunction with org. additives was also investigated with regard to polymorphs and morphol. and the structure-forming properties of the org. additives.
- 25Tomson, M. B.; Kan, A. T.; Fu, G. Control of Inhibitor Squeeze Through Mechanistic Understanding of Inhibitor Chemistry. SPE J. 2006, 11 (03), 283– 293, DOI: 10.2118/87450-PA25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XhtFChtLbM&md5=ed5da1513cd71be0d89b2621b7d415b5Control of scale inhibitor squeeze through mechanistic understanding of inhibitor chemistryTomson, Mason B.; Kan, Amy T.; Fu, GongminSPE Journal (Society of Petroleum Engineers) (2006), 11 (3), 283-293CODEN: SPJRFW; ISSN:1086-055X. (Society of Petroleum Engineers Inc.)Chem. scale inhibitors are commonly used to prevent or inhibit scale formation in oil wells. The most economic treatment of scale inhibitor is normally through chem. squeeze. However, there is little agreement regarding the primary mechanism by which the threshold scale inhibitors are retained in producing oil or gas formations as a result of squeeze procedures. Recent advances in phosphonate/rock interaction research at the Rice U. Brine Chem. Consortium have significantly improved our knowledge of what controls inhibitor placement in the formation. The pill chem. is also an important determinant for retention of carbonate reservoir. Acidic pills are mostly retained near the wellbore, while more neutralized pills move farther into the formation. Three calcium nitrilomethylene phosphonate solid phases, an amorphous phase, and two cryst. Ca2.5HNTMP phases with pKsp = 22.6 and pKsp = 24.2 are particularly important for inhibitor retention. The relative sizes of these solid phases formed are governed by the pill compn. and acidity. These results can be explained by a soln.-phase-controlled sequence of reactions. All of this information has been incorporated into a new squeeze-design software program, SqueezeSoftPitzer.
- 26Vazquez, O.; Thanasutives, P.; Eliasson, C.; Fleming, N.; Mackay, E. Modeling the Application of Scale-Inhibitor-Squeeze Retention-Enhancing Additives. SPE Prod. Oper. 2011, 26 (03), 270– 277, DOI: 10.2118/141384-PA26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtVCnu7nM&md5=7f9d740d7b04bc6b256d0fb8cfdb805fModeling the application of scale-inhibitor-squeeze-retention-enhancing additivesVazquez, O.; Thanasutives, P.; Eliasson, C.; Fleming, N.; Mackay, E.SPE Production & Operations (2011), 26 (3), 270-277CODEN: SPEPCW; ISSN:1930-1855. (Society of Petroleum Engineers)The most common method for preventing scale formation is by applying a scale-inhibitor (SI) squeeze treatment. In this process, an SI soln. is injected down a producer well into the near-wellbore formation. In the last few years, several publications have presented exptl. results, field data, and treatment methods showing enhanced squeeze lifetime because of the use of squeeze enhancers. The main purpose of this paper is to model the effect of SI-retention-enhancing additives. These additives are normally deployed in reservoirs where the SI shows poor retention in the formation matrix in order to reduce well interventions. In the last few years, a no. of techniques to enhance the SI retention have been reported in the literature, such as pptn. squeezes using calcium and/or pH-increasing additives, use of an additive package that enhances SI adsorption by crosslinking, and the injection of nondamaging concns. of kaolinite, calcium carbonate, and organosilane (a solids-fixation agent). The effect of the SI-retention enhancer is modeled as a function of the adsorption level of the additive. A sensitivity study is then presented on the effect of deploying the additive in the different stages; normally, they are deployed in the preflush stage. However, the aim of this paper is to investigate how the treatment could be optimized to achieve the longest squeeze lifetime with a fixed amt. of additive. An example of modeling a specific field treatment injecting organosilane is included. The results are compared with the field return profiles and clearly demonstrate the value such modeling can bring to the interpretation and design of field squeezes.
- 27Baraka-Lokmane, S.; Sorbie, K. S. Scale Inhibitor Core Floods in Carbonate Cores: The Influence of PH on Phosphonate-Carbonate Interactions. In SPE International Symposium on Oilfield Scale; Society of Petroleum Engineers, 2004.There is no corresponding record for this reference.
- 28Baraka-Lokmane, S.; Sorbie, K. S. Scale Inhibitor Core Floods in Carbonate Cores: Chemical Interactions and Modelling. In SPE International Oilfield Scale Symposium; Society of Petroleum Engineers, 2006.There is no corresponding record for this reference.
- 29Kan, A. T.; Fu, G.; Tomson, M. B. Adsorption and Precipitation of an Aminoalkylphosphonate onto Calcite. J. Colloid Interface Sci. 2005, 281 (2), 275– 284, DOI: 10.1016/j.jcis.2004.08.05429https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXhtVaitrbJ&md5=eb6520b1d8afc023a8a2bdb7a3ec0e93Adsorption and precipitation of an aminoalkylphosphonate onto calciteKan, Amy T.; Fu, Gongmin; Tomson, Mason B.Journal of Colloid and Interface Science (2005), 281 (2), 275-284CODEN: JCISA5; ISSN:0021-9797. (Elsevier)The mechanism of nitrilotris(methylenephosphonic acid) (H6NTMP)/calcite reaction was studied with a large no. of batch expts. where phosphonic acid was neutralized with 0 to 5 equiv of NaOH per phosphonic acid and the concn. ranged from ∼10 nmol/L to 1 mol/L. Probably the phosphonate/calcite reactions are characterized in 3 steps. At low phosphonate concn. (<1 μmol/L NTMP concn.), the phosphonate/calcite reaction can be characterized as a Langmuir isotherm. At satn., only ∼7% of the calcite surface is covered with phosphonate; presumably these are the kinks, step edges, or other imperfect sites. At higher phosphonate concns., the attachment is characterized by Ca phosphonate crystal growth to a max. of 4 to 5 surface layer thick, with solid phase stoichiometry of Ca2.5HNTMP and a const. soly. product of 10-24.11. After multiple layers of phosphonate are formed on the calcite surface, the soln. is no longer at equil. with calcite. Further phosphonate retention is probably due to mixed Ca phosphonate solid phase formation at lower pH and depleted soln. phase Ca conditions. The proposed mechanism is consistent with phosphate/calcite reaction and can be used to explain the fate of phosphonate in brines from oil producing wells and the results are compared with 2 oil wells.
- 30Baraka-Lokmane, S.; Sorbie, K. The Role of Calcium and Magnesium in the Mechanism of the Scale Inhibitor Retention in Carbonate Systems. In AAPG European Region Energy Conference and Exhibition ; 2007.There is no corresponding record for this reference.
- 31Sorbie, K. S.; Wat, R. M. S.; Todd, A. C. Interpretation and Theoretical Modeling of Scale-Inhibitor/Tracer Corefloods. SPE Prod. Eng. 1992, 7 (03), 307– 312, DOI: 10.2118/20687-PA31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK38XmtFGktLo%253D&md5=414230d983a11999f72cadf7e22d377cInterpretation and theoretical modeling of scale-inhibitor/tracer corefloodsSorbie, K. S.; Wat, R. M. S.; Todd, A. C.SPE Production Engineering (1992), 7 (3), 307-12CODEN: SPENES; ISSN:0885-9221.This paper describes a theor. approach to det. the inhibitor dynamic adsorption isotherm from coreflood expts. The main feature of the isotherm that contributes principally to the long squeeze life is highlighted. The problems of modeling near-well squeeze treatments and an improved simulator are discussed.
- 32Jarrahian, K.; Boak, L. S.; Graham, A. J.; Singleton, M. A.; Sorbie, K. S. Experimental Investigation of the Interaction between a Phosphate Ester Scale Inhibitor and Carbonate Rocks for Application in Squeeze Treatments. Energy Fuels 2019, 33 (5), 4089– 4103, DOI: 10.1021/acs.energyfuels.9b0038232https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXmt1Olt7k%253D&md5=b0d1457ad98294f6e3e26b2e5511ee4aExperimental Investigation of the Interaction between a Phosphate Ester Scale Inhibitor and Carbonate Rocks for Application in Squeeze TreatmentsJarrahian, Khosro; Boak, Lorraine S.; Graham, Alexander J.; Singleton, Mike A.; Sorbie, Ken. S.Energy & Fuels (2019), 33 (5), 4089-4103CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)Studying the interaction between scale inhibitors (SIs) and chem. reactive carbonate minerals is crucial for detg. SI retention in "squeeze" treatments. This study investigated the retention of the environmentally friendly SI, polyhydric alc. phosphate ester (PAPE), on calcite and dolomite substrates. Elemental anal. of the supernatant soln. as well as pH measurement and environmental SEM (ESEM) with energy dispersive X-ray anal. (EDX) were all used to investigate SI retention and to identify the morphol./compn. of the resultant SI-Ca ppts. Results revealed that PAPE was retained by calcite via pure adsorption at an initial test pH (pH0) of 4 and then pptd. at pH0 6. In contrast, the PAPE/dolomite system was found to be effectively pH-independent, with pptn. dominating at both pH0 values. Any temp. effect was negligible for dolomite/PAPE retention, whereas with calcite, retention was smaller at lower temp., which is attributed to the temp.-dependence of the substrate soly. Overall, the final pH of the system and the resulting degree of SI dissocn. contributed more to PAPE retention than did the final calcium concn. EDX anal. confirmed scale-inhibitor phosphorus in the deposited solids, indicating coupled adsorption/pptn. This phosphorus increased with the amt. of pptn. and with the temp., confirming the corresponding static adsorption test results.
- 33Jarrahian, K.; Sorbie, K.; Singleton, M.; Boak, L.; Graham, A. Building a Fundamental Understanding of Scale-Inhibitor Retention in Carbonate Formations. SPE Prod. Oper. 2019, DOI: 10.2118/193635-MSThere is no corresponding record for this reference.
- 34Ibrahim, J. M.; Sorbie, K.; Boak, L. S. Coupled Adsorption/Precipitation Experiments: 1. Static Results. In SPE International Conference on Oilfield Scale; Society of Petroleum Engineers, 2012.There is no corresponding record for this reference.
- 35Browning, F. H.; Fogler, H. S. Effect of Precipitating Conditions on the Formation of Calcium– HEDP Precipitates. Langmuir 1996, 12 (21), 5231– 5238, DOI: 10.1021/la960327735https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28XlvVSltrg%253D&md5=f99d6436f4d87934f976f6bc1a4319e8Effect of Precipitating Conditions on the Formation of Calcium-HEDP PrecipitatesBrowning, F. Henry; Fogler, H. ScottLangmuir (1996), 12 (21), 5231-5238CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)The focus of this paper is to define the conditions under which distinct calcium-phosphonate ppts. will form and to study how each of these ppt.'s unique chem. and phys. properties govern the release of phosphonate from porous media. The phosphonate used in this study was (1-hydroxyethylidene)-1,1-diphosphonic acid (HEDP). By variation of pH and calcium/HEDP molar ratio in soln., two distinct ppts. were formed: (1) a sol., fibrous 1:1 calcium/HEDP ppt.; and (2) a less sol., spherical 2:1 calcium/HEDP ppt. Crit. pH values that define the conditions under which each distinct ppt. forms were identified. Below the first crit. pH value, the 1:1 ppt. formed, while above the second crit. pH value, the 2:1 ppt. formed. Finally, core-flood and micromodel expts. showed that the release of 2:1 ppt. from porous media was significantly slower than that of 1:1 ppt., suggesting that the 2:1 ppt. is better suited for phosphonate treatments in oil field applications. The release of a ppt. mixt. (one which contains both distinct ppts. and has a calcium/HEDP molar ratio of 1.4:1) from a micromodel reconfirmed this phenomenon.
- 36Vetter, O. J. Oilfield Scale---Can We Handle It?. J. Pet. Technol. 1976, 28 (12), 1402, DOI: 10.2118/5879-PA36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2sXktVyhsrs%253D&md5=4907a725248da1c34bd9d1b5523316f6Oilfield scale - can we handle it?Vetter, O. J.JPT, Journal of Petroleum Technology (1976), 28 (Dec.), 1402-8CODEN: JPTJAM; ISSN:0149-2136.A review with 8 refs., of the formation, removal, and prevention of the scale of oil and gas fields.
- 37Jordan, M. M.; Sorbie, K. S.; Jiang, P.; Yuan, M. D.; Todd, A. C.; Thiery, L. The Effect of Clay Minerals, pH, Calcium and Temperature on the Adsorption of Phosphonate Scale Inhibitor onto Reservoir Core and Mineral Separates; NACE International: Houston, TX, United States, 1994.There is no corresponding record for this reference.
- 38Sorbie, K. S.; Gdanski, R. D. A Complete Theory of Scale Inhibitor Transport, Adsorption/Desorption and Precipitation in Squeeze Treatments. In SPE International Symposium on Oilfield Scale; Society of Petroleum Engineers, 2005.There is no corresponding record for this reference.
- 39Tomson, M. B.; Kan, A. T.; Fu, G.; Shen, D.; Nasr-El-Din, H. A.; Al-Saiari, H.; Al-Thubaiti, M. Mechanistic Understanding of Rock/Phosphonate Interactions and Effect of Metal Ions on Inhibitor Retention. SPE J. 2008, 13 (03), 325– 336, DOI: 10.2118/100494-PA39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXht1WmurjP&md5=4dac73d9fd9cd53b39879a6dbbcdb547Mechanistic understanding of rock/phosphonate interactions and the effect of metal ions on inhibitor retentionTomson, Mason B.; Kan, Amy T.; Fu, Gongmin; Shen, Dong; Nasr-El-Din, Hisham A.; Al-Saiari, Hamad; Al-Thubaiti, MusaedSPE Journal (Society of Petroleum Engineers) (2008), 13 (3), 325-336CODEN: SPJRFW; ISSN:1086-055X. (Society of Petroleum Engineers Inc.)This paper discusses the effects of Ca2+, Mg2+, and Fe2+ on inhibitor retention and release. Better understanding of phosphonate reactions during inhibitor squeeze treatments has direct implication on how to design and improve scale inhibitor squeeze treatments for optimum scale control. Putting various amts. of metal ions in the inhibitor pill adds another degree of freedom in squeeze design, esp. in controlling return concns. and squeeze life. Phosphonate reactions during squeeze treatments involve a series of self-regulating reactions with calcite and other minerals. However, excess calcite does not improve the retention of phosphonate due to the surface poisoning effect of Ca2+. The squeeze can be designed so that max. squeeze life is achieved by forming a low soly. phase in the formation. Addn. of Ca2+, Mg2+, and Fe2+ in the pill soln. at 0.1 to 1 molar ratios significantly improves the retention of phosphonate. Alternatively, these metal ions can be dissolved from the formation while an acidic inhibitor pill is in contact with the formation minerals. Both BHPMP and DTPMP returns were significantly extended by the addn. of metal ions (e.g., Ca2+ and Fe2+). The addn. of Mg2+ may increase the long-term return concn., which is important for some wells where a higher inhibitor return concn. is needed. The lab. squeeze simulations were compared to return data obtained from squeeze treatments performed on two wells located in a sandstone reservoir in Saudi Arabia. The sandstone formation contains significant amts. of iron-bearing minerals.
- 40Von Wandruszka, R. Phosphorus Retention in Calcareous Soils and the Effect of Organic Matter on Its Mobility. Geochem. Trans. 2006, 7 (1), 6, DOI: 10.1186/1467-4866-7-640https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BD28zovFGrtA%253D%253D&md5=eb585bbb3a132f5881ab0b9b949bdb4bPhosphorus retention in calcareous soils and the effect of organic matter on its mobilityvon Wandruszka RayGeochemical transactions (2006), 7 (), 6 ISSN:.A survey of the interactions between phosphorus (P) species and the components of calcareous soils shows that both surface reactions and precipitation take place, especially in the presence of calcite and limestone. The principal products of these reactions are dicalcium phosphate and octacalcium phosphate, which may interconvert after formation. The role of calcium carbonate in P retention by calcareous soils is, however, significant only at relatively high P concentrations - non-carbonate clays play a more important part at lower concentrations. In the presence of iron oxide particles, occlusion of P frequently occurs in these bodies, especially with forms of the element that are pedogenic in origin. Progressive mineralization and immobilization, often biological in nature, are generally observed when P is added as a fertilizer. Manure serves both as a source of subsurface P and an effective mobilizing agent. Blockage of P sorption sites by organic acids, as well as complexation of exchangeable Al and Fe in the soil, are potential causes of this mobilization. Swine and chicken manure are especially rich P sources, largely due the practice of adding the element to the feed of nonruminants. Humic materials, both native and added, appear to increase recovery of Olsen P. In the presence of metal cations, strong complexes between inorganic P and humates are formed. The influence of humic soil amendments on P mobility warrants further investigation.
- 41Matar, A.; Torrent, J.; Ryan, J. Soil and Fertilizer Phosphorus and Crop Responses in the Dryland Mediterranean Zone. In Advances in Soil Science; Springer, 1992; pp 81– 146.There is no corresponding record for this reference.
- 42Tunesi, S.; Poggi, V.; Gessa, C. Phosphate Adsorption and Precipitation in Calcareous Soils: The Role of Calcium Ions in Solution and Carbonate Minerals. Nutr. Cycl. Agroecosystems 1999, 53 (3), 219– 227, DOI: 10.1023/A:1009709005147There is no corresponding record for this reference.
- 43Sorbie, K. S.; Jiang, P.; Yuan, M. D.; Chen, P.; Jordan, M. M.; Todd, A. C. The Effect of PH, Calcium, and Temperature on the Adsorption of Phosphonate Inhibitor onto Consolidated and Crushed Sandstone. In SPE Annual Technical Conference and Exhibition; Society of Petroleum Engineers, 1993.There is no corresponding record for this reference.
- 44Tantayakom, V.; Fogler, H. S.; Charoensirithavorn, P.; Chavadej, S. Kinetic Study of Scale Inhibitor Precipitation in Squeeze Treatment. Cryst. Growth Des. 2005, 5 (1), 329– 335, DOI: 10.1021/cg049874d44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXhtVCrsbrL&md5=266b7b8931207fe89aefd2c2a8bbc7a7Kinetic Study of Scale Inhibitor Precipitation in Squeeze TreatmentTantayakom, V.; Fogler, H. S.; Charoensirithavorn, P.; Chavadej, S.Crystal Growth & Design (2005), 5 (1), 329-335CODEN: CGDEFU; ISSN:1528-7483. (American Chemical Society)Oilfield formation damage by scale formation can occur when two incompatible brine streams are mixed. A common method for preventing scale formation is the use of chem. scale inhibitors such as aminotri(methylene phosphonic acid) (ATMP). Scale inhibitors are injected and retained in the reservoir by adsorption and/or pptn. The induction time, the period between the establishment of supersatn. and the detection of a new phase, is a measure of the ability of an inhibitor soln. to remain in the metastable state. As a result, long induction times allow transport of inhibitor fluids into the near-wellbore regions without pptn. of the scale inhibitor and subsequent formation damage. In this study, an induction time model is applied to pptn. of the inhibitor (ATMP) with Ca2+ ions. The nucleation kinetics can be described by classical nucleation theory. Soln. equil. was calcd. by accounting for inhibitor dissocn. and cation-inhibitor complexing as a function of ionic strength. Conditions such as the initial concn. of inhibitor, the soln. pH, and the presence of sol. impurities significantly impact the pptn. kinetics of inhibitors. Long induction times were obsd. at low initial concns. of inhibitor, at low values of the soln. pH, and in the presence of impurities. Monovalent cation impurities (Li, Na, and K) inhibit the nucleation of Ca-ATMP to the same extent, indicating there is no effect on the different types of monovalent cations. Divalent cation impurities inhibit the nucleation of Ca-ATMP more than monovalent cations, and different divalent cations have different induction times. The redn. of nucleation rate is a result of increasing the surface free energy. This study provides an understanding of scale inhibitor pptn. kinetics which will be beneficial for delaying inhibitor pptn. in order to avoid reservoir permeability problems in near-wellbore region.
- 45Jarrahian, K.; Singleton, M.; Boak, L.; Sorbie, K. S. Surface Chemistry of Phosphonate Scale Inhibitor Retention Mechanisms in Carbonate Reservoirs. Cryst. Growth Des. 2020, 20 (8), 5356– 5372, DOI: 10.1021/acs.cgd.0c0057045https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVSms7vP&md5=63180c6041e121b45968c78409e5453fSurface Chemistry of Phosphonate Scale Inhibitor Retention Mechanisms in Carbonate ReservoirsJarrahian, Khosro; Singleton, Mike; Boak, Lorraine; Sorbie, Kenneth S.Crystal Growth & Design (2020), 20 (8), 5356-5372CODEN: CGDEFU; ISSN:1528-7483. (American Chemical Society)Building a fundamental understanding of the reactions between scale inhibitor (SI) and formation minerals is essential for effectively designing SI "squeeze" treatments. Results of bulk "apparent adsorption" (Γapp) expts. are presented for a widely used phosphonate SI, DETPMP, on calcite and dolomite mineral substrates. The apparent adsorption results are supported by (i) measuring the corresponding soln. [Ca2+] and pH values in soln., (ii) studying the surface chem. of the resulting SI/Ca ppts. using environmental SEM-energy-dispersive X-ray (ESEM-EDX) anal. to identify the morphol./compn. of the SI/Ca ppts., and (iii) a detailed mass balance anal., indicating the fate of the Ca2+ and the SI. Results revealed that DETPMP was dominantly retained by both calcite and dolomite via a pptn. mechanism (actually coupled adsorption/pptn.) for all initial pH values (pH0 2, 4, and 6) and T = 95°C, although a small region of pure adsorption (Γ) was obsd. at [DETPMP] < 100 ppm. Moreover, higher Γapp occurred on dolomite than on calcite for all initial pH0. This result is counterintuitive, because it is well-known that calcite is much more reactive than dolomite. However, final equil. pH values are higher for dolomite, compared to calcite. Thus, a higher pHfinal led to a more dissocd. DETPMP and this effect had a greater effect on SI/Ca pptn. than the higher [Ca2+] by rock dissoln. EDX anal. confirmed scale-inhibitor phosphorus in the deposited solids, indicating coupled adsorption/pptn. Supporting mass balance calcns. correlated very well with our exptl. observations, showing higher generated calcium in calcite than dolomite and less calcium generation at higher initial pH0 (lower rock dissoln.). Finally, an equil. mechanistic model describing the inhibitor dissocn., Ca-binding to the dissocd. SI species, and pptn. of the SI_Can complex, coupled to the carbonate system, is proposed to qual. explain these exptl. findings. The current work is focused on the results of bulk "apparent adsorption" (Γapp) expts. for a widely used phosphonate scale inhibitor (SI), DETPMP, on calcite and dolomite mineral substrates. The apparent adsorption results are supported by (i) measuring the corresponding soln. [Ca2+] and pH values in soln., (ii) studying the surface chem. of the resulting SI/Ca ppts. using environmental SEM energy-dispersive X-ray (ESEM-EDX) anal. to identify the morphol./compn. of the SI/Ca ppts., and (iii) a detailed mass balance anal., indicating the fate of the Ca2+ and the SI.
- 46Jarrahian, K.; Sorbie, K. S.; Singleton, M. A.; Boak, L. S.; Graham, A. J. The Effect of pH and Mineralogy on the Retention of Polymeric Scale Inhibitors on Carbonate Rocks for Application in Squeeze Treatments. SPE Prod. Oper. 2019, 34 (02), 344– 360, DOI: 10.2118/189519-PA46https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXht1ehtrvJ&md5=b01374514847759ecd6cabdeff8c52a1The effect of pH and mineralogy on the retention of polymeric scale inhibitors on carbonate rocks for precipitation squeeze treatmentsJarrahian, K.; Sorbie, K. S.; Singleton, M. A.; Boak, L. S.; Graham, A. J.SPE Production & Operations (2019), 34 (2), 344-360CODEN: SPEPCW; ISSN:1930-1863. (Society of Petroleum Engineers)The bulk "apparent adsorption" behavior (Γapp, vs. Cf) of 2 polymeric scale inhibitors (SI), polyphosphino carboxylic acid (PPCA) and phosphorus-functionalized copolymer (PFC), onto carbonate mineral substrates has been studied for initial soln. pH of 2, 4 and 6. The 2 carbonate minerals used, calcite and dolomite, are much more chem. reactive than sandstone minerals. In nearly all cases, ppts. formed at higher SI concns. were due to the formation of sparingly sol. SI/Ca complexes. A systematic study has been carried out on the SI/Ca ppts. formed, by applying both ESEM/EDX and particle size anal. (PSA). For PPCA, at all pH values, regions of pure adsorption (Γ) and coupled adsorption/pptn. (Γ/Π) are clearly obsd. for both calcite and dolomite. PFC at pH values of 4 and 6 also showed very similar behavior, with a region of pure adsorption (Γ) for PFC < 500 ppm and a region of coupled adsorption/pptn. (Γ/Π) above this level. However, the PFC/calcite case at pH = 2 showed only pure adsorption, while the PFC/dolomite case at pH = 2 again showed coupled adsorption/ pptn. at higher PFC concns. For both SIs on both carbonate substrates, pptn. is the more dominant mechanism for SI retention than adsorption. We discuss here how these observations are related to the reactivity of the different carbonate minerals, the resulting final pH (which affects the dissocn. of the SI), the Ca-SI binding, and the soly. of the resulting complex.
- 47Rietra, R. P. J. J.; Hiemstra, T.; van Riemsdijk, W. H. Interaction between Calcium and Phosphate Adsorption on Goethite. Environ. Sci. Technol. 2001, 35 (16), 3369– 3374, DOI: 10.1021/es000210b47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXkvV2qtLs%253D&md5=4f714c86a2459fc3c3e80dc588b1ab57Interaction between Calcium and Phosphate Adsorption on GoethiteRietra, Rene P. J. J.; Hiemstra, Tjisse; van Riemsdijk, Willem H.Environmental Science and Technology (2001), 35 (16), 3369-3374CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)Quant., little is known about the ion interaction processes that are responsible for the binding of phosphate in soil, water, and sediment, which det. the bioavailability and mobility of phosphate. Studies have shown that metal hydroxides are often responsible for the binding of PO43- in soils and sediments, but the binding behavior of PO43- in these systems often differs significantly from adsorption studies on metal hydroxides in lab. The interaction between PO43- and Ca adsorption was studied on goethite because Ca can influence the PO43- adsorption equil. Since adsorption interactions are very difficult to discriminate from pptn. reactions, conditions were chosen to prevent pptn. of Ca-PO43- solids. Adsorption expts. of PO43- and Ca, individually and in combination, show a strong interaction between adsorbed Ca and PO43- on goethite for conditions below the satn. index of apatite. It is shown that it is possible to predict the adsorption and interaction of PO43- and Ca on electrostatic arguments using the model parameter values derived from the single-ion systems and without invoking ternary complex formation or pptn. The model enables the prediction of the Ca-PO43- interaction for environmentally relevant calcium and phosphate concns.
- 48Karthikeyan, K. G.; Elliott, H. A.; Chorover, J. Role of Surface Precipitation in Copper Sorption by the Hydrous Oxides of Iron and Aluminum. J. Colloid Interface Sci. 1999, 209 (1), 72– 78, DOI: 10.1006/jcis.1998.589348https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXjtFaqsQ%253D%253D&md5=b9e7fa0b433409b9efd425387d0c5de6Role of surface precipitation in copper sorption by the hydrous oxides of iron and aluminumKarthikeyan, K. G.; Elliott, Herschel A.; Chorover, JonJournal of Colloid and Interface Science (1999), 209 (1), 72-78CODEN: JCISA5; ISSN:0021-9797. (Academic Press)Isotherms were developed at pH 6.9 for adsorption (ADS) and copptn. (CPT) of Cu by hydrous oxides of Fe (HFO) and Al (HAO) to study the role of sorbate/sorbent ratio in metal cation removal. For low sorbate/sorbent conditions, HFO had a higher Cu retention capacity than HAO regardless of contact methodol. For either oxide, CPT was consistently more effective than ADS in removing Cu from soln. At high sorbate/sorbent ratios, surface pptn. dominates and the oxide's net cation retention capacity depends on the nature and soly. of the ppt. formed at the oxide-H2O interface. X-ray diffraction patterns and isotherms of HJAO for both ADS and CPT suggest formation of a solid soln. [e.g., CuAl2O4(s)] with dramatically lower soly. than Cu(OH)2(s) pptd. in bulk soln. In contrast, Cu pptd. on the HFO surface exhibited a soly. comparable to the bulk pptd. Cu(OH)2(s). Therefore, at high sorbate/sorbent ratios, HAO has a higher Cu apparent sorption capacity than HFO. The relative utility of these oxides as metal scavengers thus depends markedly on sorbate/sorbent conditions. (c) 1999 Academic Press.
- 49Wang, X.; Hu, Y.; Tang, Y.; Yang, P.; Feng, X.; Xu, W.; Zhu, M. Phosphate and Phytate Adsorption and Precipitation on Ferrihydrite Surfaces. Environ. Sci. Nano 2017, 4 (11), 2193– 2204, DOI: 10.1039/C7EN00705A49https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhsFKisbvP&md5=d09bafc2b85f89cff2e68f851552d950Phosphate and phytate adsorption and precipitation on ferrihydrite surfacesWang, Xiaoming; Hu, Yongfeng; Tang, Yadong; Yang, Peng; Feng, Xionghan; Xu, Wenqian; Zhu, MengqiangEnvironmental Science: Nano (2017), 4 (11), 2193-2204CODEN: ESNNA4; ISSN:2051-8161. (Royal Society of Chemistry)Phosphorus (P) sorption on mineral surfaces largely controls P mobility and bioavailability, hence its pollution potential, but the sorption speciation and mechanism remain poorly understood. We have identified and quantified the speciation of both phosphate and phytate sorbed on ferrihydrite with various P loadings at pH 3-8 using differential at. pair distribution function (d-PDF) anal., synchrotron-based X-ray diffraction (XRD), and P and Fe K-edge X-ray absorption near edge structure (XANES) and attenuated total reflectance-Fourier transform IR (ATR-FTIR) spectroscopy. With increasing P sorption loading for both phosphate and phytate, the sorption mechanism transits from bidentate-binuclear surface complexation to unidentified ternary complexation and to pptn. of amorphous FePO4 and amorphous Fe-phytate. At a given P sorption loading, phosphate ppts. more readily than phytate. Both phosphate and phytate promote ferrihydrite dissoln. with phytate more intensively, but the dissolved FeIII concn. in the bulk soln. is low because the majority of the released FeIII ppt. with the anions. Results also show that amorphous FePO4 and amorphous Fe-phytate have similar PO4 local coordination environment. These new insights into the P surface complexation and pptn., and the ligand-promoted dissoln. behavior improve our understanding of P fate in soils, aquatic environment and water treatment systems as mediated by mineral-water interfacial reactions.
- 50Li, L.; Stanforth, R. Distinguishing Adsorption and Surface Precipitation of Phosphate on Goethite (α-FeOOH). J. Colloid Interface Sci. 2000, 230 (1), 12– 21, DOI: 10.1006/jcis.2000.707250https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXms1Wjtbo%253D&md5=e8edfd449ffc2aa715b4b5f9d8c25280Distinguishing adsorption and surface precipitation of phosphate on goethite (α-FeOOH)Li, Li; Stanforth, RobertJournal of Colloid and Interface Science (2000), 230 (1), 12-21CODEN: JCISA5; ISSN:0021-9797. (Academic Press)The reaction between phosphate and goethite changes from adsorption into surface pptn. with no discernible changes in the adsorption isotherm. Distinguishing the 2 processes, by plotting the loss of phosphate from soln. vs. final phosphate concn. or based on theor. calcns., is difficult. This paper presents a method for distinguishing between the 2 processes based on the change in zeta potential with increasing adsorption. During adsorption, the incoming phosphate results in a more neg. surface charge as the more acidic phosphate ion replaces a less acidic surface hydroxyl. The amt. of neg. charge imparted to the surface should vary linearly with surface coverage for adsorption. Phosphate that is bound to a surface ppt., on the other hand, imparts a much smaller neg. charge to the surface, since there is no change in the character of the surface due to the addnl. phosphate. Zeta potential measurements of phosphated goethite at varying soln. pH values and surface coverages are used to det. the transition point from adsorption to surface pptn. The transition occurs at dissolved phosphate concns. much lower than those calcd. for phosphate in equil. with goethite and iron phosphate. (c) 2000 Academic Press.
- 51Boak, L. S.; Sorbie, K. New Developments in the Analysis of Scale Inhibitors. SPE Prod. Oper. 2010, 25 (04), 533– 544, DOI: 10.2118/130401-PA51https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsFSgurzM&md5=38afe3cf64e0ec75a0184a2be7d6b863New developments in the analysis of scale inhibitorsBoak, L. S.; Sorbie, K. S.SPE Production & Operations (2010), 25 (4), 533-544CODEN: SPEPCW; ISSN:1930-1855. (Society of Petroleum Engineers)Scale inhibitors (SIs) are used to control oilfield scale formation, and the ability to analyze these species is very important such that SI concns. as low as 0.5-ppm active need to be measured accurately. If phosphorus is present in the SI mol., then inductively-coupled-plasma (ICP)-based methods may be used for anal. However, the oil industry's increasing requirement to be environmentally friendly means that polymeric "green" SIs are now being used more, which raises issues concerning detection techniques (i.e., ICP vs. wet-chem. techniques). ICP detection for SIs is generally easier, but if it cannot be used, then at least time-saving improvements to wet-chem. techniques are extremely beneficial. In this paper, anal. approaches are described that have been used recently to improve chem. SI assay, esp. at low near-threshold levels (a few ppm active of SI). Progress is reported in five areas of SI anal.:. 1. Assay of sulfonated copolymer (VS-Co) was not possible by straightforward anal. without extensive dialysis and sample prepn. However, calibrations and repeats of accuracy similar to that of the C18 were found for VS-Co using amino-Pr (NH2) cartridges and the Hyamine method. 2. The Oasis 2 × 4 method has been applied to SI anal., and this is able to assay all types of polymeric SIs in principle. This method has been used to detect a VS-Co SI in a wide variety of different brine salinities from distd. water (DW) to high-salinity formation waters (FW) (e.g., a Heron-type FW). Although achievable under these different conditions, there was a significant decrease in the absorbance signals recorded with increasing salinity that was not significantly improved by a higher-capacity sorbent cartridge. 3. Various elements have been assayed in the oil phase using the ICP method. Calibrations and accurate repeats within 5 to 10% error were achieved. After solving compatibility issues, the concn. of an oil-tolerant SI was detd. successfully using calibrations and accurate repeats over a range of 0 to 10 ppm and 0 to 2,500 ppm active SI. 4. A matrix-matching Hyamine technique has been developed that allows any chloride-ion effects on the chelating process between the Hyamine and SI to be negated, allowing accurate anal. of low-polymeric SI concns. 5. ICP and wet-chem. techniques have been able to accurately detect a P-tagged (phosphorus-tagged) copolymer-type SI. The ability to apply two independent anal. methods to a given species offers some important advantages when more than one SI is deployed in a field system. In this work, excellent correlation is obsd. between the wet-chem. and ICP assay methods for this P-tagged SI. This study updates and adds to the set of anal. methods and procedures reported for SI anal. almost 20 years ago and are described in our Flow Assurance and Scale Team (FAST) lab. procedures manual.
- 52Cooney, D. O. Adsorption Design for Wastewater Treatment; CRC Press, 1998.There is no corresponding record for this reference.
- 53Xu, N.; Chen, M.; Zhou, K.; Wang, Y.; Yin, H.; Chen, Z. Retention of Phosphorus on Calcite and Dolomite: Speciation and Modeling. RSC Adv. 2014, 4 (66), 35205– 35214, DOI: 10.1039/C4RA05461J53https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtFOjtL3M&md5=6aee218d4bd9403c9ad38813654b80eaRetention of phosphorus on calcite and dolomite: speciation and modelingXu, Nan; Chen, Ming; Zhou, Kairong; Wang, Yunlong; Yin, Hongwei; Chen, ZhigangRSC Advances (2014), 4 (66), 35205-35214CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)The intensive application of phosphate fertilizers in agriculture has created an important source of diffuse phosphorus pollution. The interaction of phosphorus with carbonate minerals plays a role in the fate and transport of phosphorus in soil. The object of the present study was to investigate the speciation of phosphorus on two common carbonate minerals, calcite and dolomite, using a combination of batch expts., ATR-FTIR spectroscopy, XANES anal., and diffuse layer modeling. Within the pH range 6.0-7.0, the retention of phosphorus by calcite and dolomite is mainly attributed to the formation of amorphous calcium phosphate (Ca3(PO4)2, ACP), dibasic calcium phosphate (CaHPO4·2H2O, DCP), and hydroxyapatite (Ca5(PO4)3OH, HAP). At pH ≥ 8.0 the immobilized phosphorus takes the form of complexes =CaPO4Ca0/=sCaPO4Ca0 on the surface of calcite, followed by the formation of Ca-P phases, including ACP, DCP, and HAP, with increasing phosphorus levels (>2 mg L-1). However, the dolomite surface is initially dominated by the adsorption complex =MgHPO4Ca+ at =Mg sites, and at higher phosphorus levels it then grows due to Ca-P phases and the formation of newberyite (MgHPO4). It is interesting to note that the Mg content in dolomite favors the rapid growth of DCP at phosphorus levels >200 mg L-1. As a result, at pH ≥ 8.0, dolomite shows a stronger capacity for immobilizing phosphorus than does calcite. Dolomite therefore serves as a better phosphorus sink than calcite in calcareous soil environments.
- 54Wei, H.; Han, L.; Tang, Y.; Ren, J.; Zhao, Z.; Jia, L. Highly Flexible Heparin-Modified Chitosan/Graphene Oxide Hybrid Hydrogel as a Super Bilirubin Adsorbent with Excellent Hemocompatibility. J. Mater. Chem. B 2015, 3 (8), 1646– 1654, DOI: 10.1039/C4TB01673D54https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhs1Kqtw%253D%253D&md5=2f1745c747fb3521d7539e2712b61084Highly flexible heparin-modified chitosan/graphene oxide hybrid hydrogel as a super bilirubin adsorbent with excellent hemocompatibilityWei, Houliang; Han, Lulu; Tang, Yongchao; Ren, Jun; Zhao, Zongbin; Jia, LingyunJournal of Materials Chemistry B: Materials for Biology and Medicine (2015), 3 (8), 1646-1654CODEN: JMCBDV; ISSN:2050-7518. (Royal Society of Chemistry)As a pathogenic toxin, bilirubin is generally removed from blood by hemoperfusion for the remission of liver disease or to gain time for patients waiting for liver transplantation. However, the development of bilirubin adsorbents with excellent mech. properties, adsorption performance and hemocompatibility is still a considerable challenge. In this work, a heparin-modified chitosan/graphene oxide hybrid hydrogel (hep-CS/GH) has been developed for bilirubin adsorption using a lyophilization-neutralization-modification strategy. The as-prepd. hybrid hydrogel displayed a unique foam-like porous structure and excellent mech. flexibility. It was revealed that the incorporation of graphene oxide into the chitosan matrix enhanced both the compressive strength and the Young's modulus of the hybrid hydrogel, as well as its adsorption capacity for bilirubin. The max. adsorption capacity of hep-CS/GH for bilirubin was 92.59 mg g-1, according to the Langmuir isotherm model. It was demonstrated that hep-CS/GH successfully competed with albumin, and could effectively adsorb bilirubin from a bilirubin-enriched serum. After the hydrogel was modified with heparin, protein adsorption, platelet adhesion and hemolysis were reduced, and the plasma clotting time was prolonged from 4.1 to 23.6 min, indicating the superior hemocompatibility of hep-CS/GH. Therefore, this study may pave the way for improving the performance of the adsorbent in removing blood toxins.
- 55Spinthaki, A.; Demadis, K. D. Chemical Methods for Scaling Control. In Corrosion and Fouling Control in Desalination Industry; Springer, 2020; pp 307– 342.There is no corresponding record for this reference.
- 56Shaw, S. S. Investigation into the Mechanisms of Formation and Prevention of Barium Sulphate Oilfield Scale; Heriot-Watt University, 2012.There is no corresponding record for this reference.
- 57Shaw, S. S.; Sorbie, K. S. Structure, Stoichiometry, and Modeling of Calcium Phosphonate Scale-Inhibitor Complexes for Application in Precipitation-Squeeze Processes. SPE Prod. Oper. 2014, 29 (02), 139– 151, DOI: 10.2118/164051-PA57https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXptlOgsQ%253D%253D&md5=f06a5debf9e26a6d8e6337990202f748Structure, stoichiometry, and modeling of calcium phosphonate scale-inhibitor complexes for application in precipitation-squeeze processesShaw, S. S.; Sorbie, K. S.SPE Production & Operations (2014), 29 (2), 139-151, 13 pp.CODEN: SPEPCW; ISSN:1930-1863. (Society of Petroleum Engineers)Phosphonate scale inhibitors (SIs) applied in downhole-squeeze applications may be retained in the near-well formation through adsorption and/or pptn. mechanisms. In this paper, we focus on the properties of pptd. calcium phosphonate complexes formed by nine common phosphonate species. The stoichiometry [calcium ion to phosphorous (Ca2+/P) ratios] in various ppts. is established exptl., and the effect of soln. pH on the molar ratio of Ca2+/P in the ppt. is investigated. All static pptn. tests were carried out in distd. water (DW), with only Ca2+ [as calcium chloride (CaCl2)] and SI present in the system at test temps. from 20 to 95°C. The molar ratio of Ca2+/P in the solid ppt. was detd. by assaying for Ca2+ and P in the supernatant liq. under each test condition by inductively coupled plasma (ICP) spectroscopy (Ca0 and P0 are known, but are also measured exptl.). We show exptl. that the molar ratio of pptd. Ca2+/P (or Ca2+/SI; or n in the SI-Can complex) depends on the SI itself and is a function of pH for all phosphonates tested. It is found that, as pH increases, the molar ratio of Ca2+/P (n in the SI-Can) in the ppt. increases up to a theor. max., depending on the chem. structure of the phosphonate. Our findings corroborate proposed SI-metal complex-ion structures, which were presented previously in Shaw et al. (2012c), as discussed in detail in this paper. In addn., the pptn. behavior of the various compds. is modeled theor. by developing and solving a set of simplified equil. equations. We find that the pptn. behavior can be modeled, but only if a fraction (β) of "non-SI" of the initial phosphonate SI is taken into account. The quantity β can be as high as 0.2 (i.e., approx. 20% non-SI), although there is a degree of variability in this factor from product to product. However, good quant. agreement is shown comparing the predictions of the equil.-soly. model with the expt. Such models can be used directly in the modeling of field phosphonate pptn.-squeeze treatments.
- 58Silva, D. Thermodynamic Modelling of the Precipitation Chemistry of Scale Inhibitors and Divalent Cations (Ca and Mg). In Chemistry in the Oil Industry XVI: New Chemistries for Old Problems; Manchester, United Kingdom, 2019.There is no corresponding record for this reference.
- 59Viveros-Ceballos, J. L.; Ordóñez, M.; Sayago, F. J.; Cativiela, C. Stereoselective Synthesis of α-Amino-C-Phosphinic Acids and Derivatives. Molecules 2016, 21 (9), 1141, DOI: 10.3390/molecules2109114159https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhslWnsbjL&md5=c9a5f8894ab1407b3903b19f09384aa4Stereoselective synthesis of α-amino-C-phosphinic acids and derivativesViveros-Ceballos, Jose Luis; Ordonez, Mario; Sayago, Francisco J.; Cativiela, CarlosMolecules (2016), 21 (9), 1141/1-1141/31CODEN: MOLEFW; ISSN:1420-3049. (MDPI AG)A review. α-Amino-C-phosphinic acids and derivs. are an important group of compds. of synthetic and medicinal interest and particular attention has been dedicated to their stereoselective synthesis in recent years. Among these, phosphinic pseudopeptides have acquired pharmacol. importance in influencing physiol. and pathol. processes, primarily acting as inhibitors for proteolytic enzymes where mol. stereochem. has proven to be crit. This review summarizes the latest developments in the asym. synthesis of acyclic and phospha-cyclic α-amino-C-phosphinic acids and derivs., following in the first case an order according to the strategy used, whereas for cyclic compds. the nitrogen embedding in the heterocyclic core is considered. In addn. selected examples of pharmacol. implications of title compds. are also disclosed.
- 60Valiakhmetova, A.; Sorbie, K. S.; Boak, L. S.; Shaw, S. S. Solubility and Inhibition Efficiency of Phosphonate Scale Inhibitor_calcium_magnesium Complexes for Application in a Precipitation-Squeeze Treatment. SPE Prod. Oper. 2017, 32 (03), 343– 350, DOI: 10.2118/178977-PA60https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhs1Ogu77L&md5=d2a1b1eda4638e918b716e18d55b10f7Solubility and inhibition efficiency of phosphonate scale inhibitor_calcium_magnesium complexes for application in a precipitation-squeeze treatmentValiakhmetova, A.; Sorbie, K. S.; Boak, L. S.; Shaw, S. S.SPE Production & Operations (2017), 32 (3), 343-350CODEN: SPEPCW; ISSN:1930-1863. (Society of Petroleum Engineers)Scale-inhibitor (SI) squeeze treatments are applied extensively for controlling scale formation during oil and gas prodn. The current research involves phosphonate/metal ppt. studies in the context of pptn.-squeeze treatments. The main focus here is on the pptn. and soly. behavior of the SI_ calcium (Ca)_magnesium (Mg) complexes of HEDP (a diphosphonate), DETPMP (a pentaphosphonate), and OMTHP (a hexaphosphonate); these mixed phosphonate/divalent ppts. are denoted as SI_Can1_Mgn2, where n1 and n2 are the stoichiometric ratios of Ca and Mg to SI, resp. Pptn. expts. with SI_Can1_Mgn2 species were carried out over a temp. range of 20 to 95 C, while varying the Mg/Ca molar ratio over a wide range from all Ca to all Mg. These ppts. were formed in MgCl2·6H2O/CaCl2·6H2O brine solns. with appropriate molar ratios of metals, then sepd. from the supernatant by filtration. Subsequently, the soly. of the collected ppt. was found in a soln. of the same Mg/Ca molar compn. from which it was prepd. In this type of expt., the soly. of the SI_Can1_Mgn2 ppt. without any respeciation is detd. In addn., another type of soly. expt. was carried out for a ppt. formed in a brine with one fixed Mg/Ca ratio; this was subsequently placed into a soln. with different Mg/Ca compns. (from all Ca to all Mg). In these expts., respeciation of the ppt. may occur. We have been able to establish the soly. (Cs) of the ppts. of three SIs (HEDP, OMTHP, and DETPMP) as a function of both temp. and Mg/Ca molar ratio. It has been shown that the soly. of ppt. is in equil. with Mg and Ca concns. in soln., and any change of these parameters leads to soly. variation. All phosphonate/metal ppts. become less sol. with increasing temp. and much more sol. with an increasing proportion of Mg. We have found that any change in Mg/Ca ratio of brine does lead to a redistribution of Ca, Mg, and SI concns. in a given ppt. and bulk soln., and, hence, leads to some variation in the ppt. soly. Addnl., the inhibition efficiency (IE) of pptd. and then redissolved HEDP, OMTHP, and DETPMP SIs was tested and compared with the IE of industrial stock products. We show that, unlike polymeric SI ppts., the inhibition activity of phosphonate SIs does not depend significantly on the pptn. process, and the IE of pptd. and redissolved SI_Ca and SI_Ca_Mg complexes is very close to that of the industrial stock solns. These results can be used directly for modeling phosphonate pptn.-squeeze treatments, and the significance of these results for field applications is explained.
- 61Sorbie, K. S.; Laing, N. How Scale Inhibitors Work: Mechanisms of Selected Barium Sulphate Scale Inhibitors across a Wide Temperature Range. In SPE International Symposium on Oilfield Scale; Society of Petroleum Engineers, 2004.There is no corresponding record for this reference.
- 62Pourmohammadbagher, A.; Shaw, J. M. Probing Contaminant Transport to and from Clay Surfaces in Organic Solvents and Water Using Solution Calorimetry. Environ. Sci. Technol. 2015, 49 (18), 10841– 10849, DOI: 10.1021/acs.est.5b0241662https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlOntLfI&md5=d9897c19bfb316fb4485019b323ed639Probing Contaminant Transport to and from Clay Surfaces in Organic Solvents and Water Using Solution CalorimetryPourmohammadbagher, Amin; Shaw, John M.Environmental Science & Technology (2015), 49 (18), 10841-10849CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)Clays, in tailings, are a significant ongoing environmental concern in the mining and oilsands prodn. industries, and clay rehabilitation following contamination poses challenges episodically. Understanding the fundamentals of clay behavior can lead to better environmental impact mitigation strategies. Systematic calorimetric measurements are shown to provide a framework for parsing the synergistic and antagonistic impacts of trace (ppm level) components on the surface compns. of clays. The enthalpy of soln. of as-received and contaminated clays, in as-received and contaminated org. solvents and water, at 60° and atm. pressure, provides important illustrative examples. Clay contamination included pre-satn. of clays with water and org. liqs. Solvent contamination included the addn. of trace water to org. solvents and trace org. liqs. to water. Enthalpy of soln. outcomes are interpreted using a quant. mass and energy balance modeling framework that isolates terms for solvent and trace contaminant sorption/desorption and surface energy effects. Underlying surface energies are shown to dominate the energetics of the solvent-clay interaction, and org. liqs. as solvents or as trace contaminants are shown to displace water from as-received clay surfaces. This approach can be readily extended to include pH, salts, or other effects and is expected to provide mechanistic and quant. insights underlying the stability of clays in tailings ponds and the behaviors of clays in diverse industrial and natural environments.