Calcium Sulfate Scale Formation Research Articles

Triple effective water treatment agent: P(AA/AMPS) capped sulfur quantum dots boast remarkable antiscale, antibacterial, and real-time tracking capabilities

Recent research has explored nanomaterials as sustainable scale inhibitors for water treatment. This research specifically delved into the development of environmentally benign antimicrobial sulfur quantum dot scale inhibitors (P(AA/AMPS)-SQDs) by capping P(AA/AMPS) with varying molecular weights. The synthesized P(AA/AMPS)-SQDs underwent thorough characterization employing high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and zeta potential analysis. The inhibitory efficacy of P(AA/AMPS)-SQDs on calcium carbonate (CaCO3) and calcium sulfate (CaSO4) scale formation was conducted under diverse conditions, including scale inhibitor concentration, reaction time, temperature, and pH using scanning electron microscopy and X-ray powder diffraction techniques. Remarkably, the water agent P(AA/AMPS)-SQDs showcased exceptional fluorescence, water solubility, and resilience to high temperatures. At specified concentrations, P(AA/AMPS)-SQDs demonstrated remarkable inhibition efficiencies, with over 98 % inhibition against the CaCO3 scale at 20 mg/L and over 97 % inhibition against the CaSO4 scale at 0.5 mg/L, significantly outperforming traditional scale inhibitors. Furthermore, P(AA/AMPS)-SQDs exhibited almost 100 % inhibition efficiency against Bacillus subtilis at a dosage of 150 mg/L. Furthermore, molecular dynamics simulation and quantum chemical calculations were employed to clarify the scale inhibition mechanisms of P(AA/AMPS)-SQDs. This multifunctional water treatment agent, integrating scale inhibition, antimicrobial properties, and online monitoring capabilities, lays a solid foundation for potential applications in engineering domains.

Performance improvement of a modified copolymer as an antiscalant and microbial growth inhibitor

Prevention and control of calcium sulfate scale formation and microbial growth accumulation in water handling systems is one of the challenging operations to avoid corrosion and flow restriction through equipment. This paper examines modified low-molecular-weight Maleic Anhydride (MAn) copolymerized by Acrylamide (AAm), which was successfully synthesized, developed, and analyzed as a multifunctional non-phosphorous antiscalant to overcome these problems. The structure, morphology, and thermal property of poly(MAn-co-AAm) were characterized. The intended structure and copolymerization were confirmed through GPC, FT-IR, SEM, and EDX analyses. The high thermal resistivity up to 400 °C was observed via TGA analysis. The standard NACE TM0374 methodologies were applied to evaluate the scale controlling capacity of poly(MAn-co-AAm) at various dosages (1–20 ppm), temperatures (50–90 °C), and regular intervals of 24–72 h. Interestingly, for low values of poly(MAn-co-AAm), efficiency was found 100% at the third level within the standard state. Further SEM and XRD analyses emphasized the validity of successful inhibition of calcium sulfate scale formation in comparison with other antiscalant agents, even at very low concentrations. In addition, antibacterial properties of poly(MAn-co-AAm) were investigated against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The results revealed that the developed copolymer possesses a wide antibacterial activity against both Gram-negative and Gram-positive bacteria. With this in mind, poly(MAn-co-AAm) is believed to be an effective and economical multifunctional antiscalant in cooling water treatment systems.

Co-Deposition Mechanisms of Calcium Sulfate and Calcium Carbonate Scale in Produced Water

Co-precipitation of mineral-based salts during scaling remains poorly understood and thermodynamically undefined within the water industry. This study focuses on investigating calcium carbonate and calcium sulfate mixed precipitation in scaling. Scaling is often observed in the produced water supply as a result of treatment processes. Co-precipitation results were compared with experimental results of a single salt crystallization. Several parameters were carefully monitored, including the electrical conductivity, pH value, crystal morphology and crystal form. The existence of the calcium carbonate scale in the mixed system encourages the loose calcium sulfate scale to become more tightly packed. The mixed scale was firmly adhered to the beaker, and the adhesion of the co-deposition product was located between the pure calcium sulfate scale and the pure calcium carbonate scale. The crystalline form of calcium sulfate was gypsum in both pure material deposition and mixed deposition, while the calcium carbonate scale was stable in calcite form in the pure material deposition. In the co-deposition, apart from calcite form, some calcium carbonate scale crystals had metastable vaterite form. This indicated that the presence of SO42− ions reduced the energy barrier of the calcium carbonate scale and hindered its transformation from a vaterite form to a calcite one, and the increase in HCO3− content inhibited the formation of calcium sulfate scale.

Increasing inhibition performance of simultaneous precipitation of calcium and strontium sulfate scales using a new inhibitor — Laboratory and field application

In this work, the calcium sulfate (anhydrite) and strontium sulfate precipitation simultaneous prediction was performed at various reservoir pressures, temperatures, and mixing ratios of injection and formation water. In addition, in order to prevent the precipitation of calcium and strontium sulfate scale, the inhibition performance of five various well-known scale inhibitors was evaluated by conducting different experiments. The results showed that the possibility of calcium and strontium sulfate precipitation was directly proportional to the temperature and inversely proportional to pressure. The worst scenario for the simultaneous calcium and strontium sulfate scale formation was observed in a mixing ratio of 1:1 injection and formation water. A mixture of reagents (new inhibitors) — DPAAI (three phosphonate scale inhibitors, ammonium bifluoride, isopropyl alcohol, and water) was developed in order to enhance the prevention performance of calcium and strontium sulfate salt precipitation. DPAAI had an efficiency of 94% under static conditions, and its effectiveness was not changed by increasing the temperature up to 150 °C. The induction period of strontium sulfate crystallization in the presence of DPAAI was 70 min, which was 2.89 times longer than in a blank case. The interfacial tension of DPAAI and oil was reduced more than 10 times in the presence of an alcohol propoxy sulfate at a mass concentration of 1.5%. Furthermore, the rock permeability with the use of DPAAI was improved from 33% to 95% of the initial permeability. The squeeze lifetime of DPAAI for preventing the simultaneous calcium and strontium sulfate scale precipitation was about 85% longer than the squeeze lifetime of the investigated common phosphonate scale inhibitors.

Design and Application of High-Temperature Raw-Seawater-Based Fracturing Fluids

Summary Typically, water-based fracturing treatments consume a large volume of fresh water. Providing consistent freshwater sources is difficult and sometimes not feasible, especially in remote areas and offshore operations. Therefore, several seawater-based fracturing fluids have been developed in an effort to preserve freshwater resources. However, none of these fluids minimizes fracture-face skin and proppant-conductivity impairment, which can be critical for unconventional well treatments. Several experiments and design iterations were conducted to tailor raw-seawater-based fracturing fluids. These fluids were designed to have rheological properties that can transport proppant under dynamic and static conditions. The optimized seawater-based fracturing-fluid formulas were developed such that no scale forms when additives are mixed in or when the fracturing-fluid filtrate is mixed with different formation brines. The tests were conducted using a high-pressure/high-temperature (HP/HT) rheometer, coreflood, and by aging cells at 250 to 300°F. The developed seawater-based fracturing fluids were optimized with an apparent viscosity greater than 100 cp at a shear rate of 100 seconds–1 and a temperature of 300°F for more than 1 hour. The use of polymeric- and phosphonate-based scale inhibitors (SIs) prevented the formation of severe calcium sulfate (CaSO4) scale in mixtures of seawater and formation brines at 300°F. Controlling the pH of fracturing fluids prevented magnesium and calcium hydroxide precipitation that occurs at a pH value of greater than 9.5. Most importantly, SIs had a negative effect on the viscosity of seawater fracturing fluid during testing because of their negative interaction with metallic crosslinkers. The developed seawater-based fracturing fluids were applied for the first time in an unconventional and a conventional carbonate well and showed very promising results; details of field treatments are discussed in this paper.

Piper betle leaf extract as a green inhibitor of calcium sulphate (CaSO4) scale formation

The addition of Piper betle leaf extract with the concentration of 450 ppm as a green inhibitor of CaSO4 scale formation at the concentration of growth solution of 0.05 M and temperature of 90°C was carried out using a seeded experiment method. The experiments were performed with observing the precipitation change of CaSO4 crystals growth obtained. In order to prove the efficiency of the inhibitor in inhibiting the formation of CaSO4 crystals, the changes of the crystal morphology were investigated by scanning electron microscopy (SEM). The research results showed that Piper betle leaf extract was able to inhibit the formation of CaSO4 scale indicated with the morphology change of the CaSO4 crystals after the addition of this inhibitor. The ability of Piper betle leaf extract as an inhibitor of the formation of CaSO4 is 47.07%.

The influence of gambier extract modification as inhibitor of calcium sulfate scale formation

Scale formation is a serious problem in many industries, especially in oil and gas industries. Therefore, in order to control the problems, this research studied the effect of the addition of gambier extract modified with kemenyan extract on the growth of calcium sulfate (CaSO4) scale formation as a green inhibitor. The crystallization experiments were carried out by using unseeded experiment method at temperature of 90°C. The CaSO4 crystals obtained with and without the addition of inhibitor were analyzed by scanning electron microscopy (SEM), particle size analyzer (PSA), and X-ray diffraction (XRD). The results of this experiment show that the addition of the combination of gambier and kemenyan extract with ratio of 5:9 can inhibit the growth of CaSO4 crystals with the inhibition effectivity of 39.88%. These results were supported from the SEM and PSA data showing that the crystal size and particle size distribution of the CaSO4 in the addition of the inhibitor are smaller than without the addition of inhibitor. In addition, analysis using XRD showed that CaSO4 crystals undergo a change in crystalline phase with the addition of inhibitors.

Increasing efficiency of calcium sulfate scale prevention using a new mixture of phosphonate scale inhibitors during waterflooding

Inorganic salt precipitation is one of the main problems in oilfield operations. Different factors affect scale formation and inhibition. Calcium sulfate scale formation occurs during waterflooding due to incompatibility of injection and formation waters. In this work, synthetic formation and injection waters were prepared to determine the influence of reservoir conditions (temperature and pressure), and mixing ratio of the waters on calcium sulfate scale deposition during waterflooding. A new mixture of phosphonate scale inhibitors (SI) was developed for increasing the inhibition efficiency of calcium sulfate scale formation in oil reservoirs. The developed mixture consists of three different industrial phosphonate SI and some additives. The concentrations of components of the developed mixture of phosphonate SI were determined on the basis of a synergistic inhibition effect. The maximum value of the synergistic inhibition effect was about 1.091. Performance of the developed mixture and four different industrial SI (HEDP, ATMP, PPCA and DTPMP) was determined by jar test. The experimental results showed that the developed mixture of phosphonate SI has a better inhibition performance than the industrial inhibitors under any conditions. Its effectiveness was more than 90% at any reservoir temperature (60–120 °C) and content of formation water in the solution (10–90%). Furthermore, a minimum inhibitory concentration of the developed mixture of phosphonate SI was about 25 mg/L. Moreover, formation damage due to calcium sulfate precipitation in carbonate rock samples with and without the use of scale inhibitors was investigated. Without the addition of any SI, the damaged permeability was about 58% of the initial rock permeability. The damaged permeability in the presence of the developed mixture of phosphonate SI was about 93.5% of the initial permeability of the used rock samples. Also, a new correlation was developed for predicting a permeability reduction of the rock samples due to calcium sulfate precipitation. The coefficient of determination between experimental and predicted (form correlation) data was 0.99. In addition, the developed mixture of phosphonate SI had the enhanced adsorption/desorption capacities. Its squeeze lifetime was longer up to 22.6% than other inhibitors. The corrosion rate in the solution of the developed mixture of phosphonate SI was lower than 0.063 mm/y at any concentration.

Strategies for calcium sulphate scale control in hydrometallurgical processes at 80 °C

In order to control calcium sulphate scale formation in hydrometallurgical processes, strategies for lowering the concentration of soluble calcium in simulated solutions at 80°C (conditions in the Pressure Acid Leach thickener tank) below the solubility limit of calcium sulphate at 140°C (conditions in the medium pressure slurry pre-heater) were investigated. Reagents known to form insoluble products with calcium such as: Na2CO3, H2C2O4, Na2C2O4 and Na3PO4, were investigated and the kinetics and selectivity of the precipitation process were evaluated as well. Both Na2CO3 and Na2C2O4 successfully and selectively lowered aqueous calcium concentration below the solubility limit at 80°C at 1:1 stoichiometric ratios with respect to calcium, while excess of H2C2O4 was required in order to achieve advanced calcium removal; Na2CO3 in a 2:1 ratio reached even lower values, below the solubility limit at 140°C. Na3PO4 in a 1:1 ratio proved highly inefficient, removing only 67% of the total calcium.

Influence of Calix[4]arene Derived Compound on Calcium Sulphate Scale Formation

Influence of Calix[4]arene Derived Compound on Calcium Sulphate Scale Formation

Synthesis of a diallylammonio propanephosphonate-alt -(sulfur dioxide) copolymer and its evaluation as an antiscalant in desalination plants

The cationic monomer N,N-diallyl-3-(diethylphosphonato)propylammonium chloride was cyclo-copolymerized with sulfur dioxide in dimethylsulfoxide using azoisobutyronitrile as initiator to afford a cationic polyelectrolyte (CPE) having a (diethylphosphonato)propyl pendent moiety. The CPE on acidic hydrolysis of the diester groups gave pH-responsive polyzwitterionic acid (PZA) which on treatment with one and two equivalents of NaOH gave zwitterionic/anionic polyelectrolyte (ZAPE) and dianionic polyelectrolyte (DAPE), respectively. The solution properties of CPE, PZA, ZAPE and DAPE were investigated in detail using a viscometric technique. For comparison, the solution properties of the polymers were correlated with those of the structurally similar polyzwitterion prepared from copolymerization of the corresponding zwitterionic monomer ethyl-3-(N,N-diallylammonio)propanephosphonate and sulfur dioxide. Evaluation of antiscaling properties using concentrated brine solutions revealed that DAPE at a meagre concentration of 10 ppm is very effective in inhibiting the formation of calcium sulfate scale, and as such can be used effectively as an antiscalant in reverse osmosis plants. © 2013 Society of Chemical Industry

The Study of Calcium Sulfate Scale Formation during Water Injection in Iranian Oil Fields at Different Pressures

Scale formation in surface and subsurface oil and gas production equipment has been recognized to be one of the major operational problems. It has also been recognized as one of the major causes of formation damage either in injection or producing wells. Scale contributes to equipment wear and corrosion and flow restriction, thus resulting in a decrease in oil and gas production. This article presents the predicting of calcium sulfate scale tendency of formation water, injection water, and mixing of injection water with formation water at different pressures. The experimentally measured chemical analyses of formation water and injection water were used by OLI ScaleChem software to determine the tendency of scale formation. This software has been applied to investigate the potential of calcium sulfate scale tendency in Iranian oil fields, either in onshore or offshore fields where water injection is being performed for desalting units' water disposal purpose or as a method of secondary recovery or reservoir pressure maintenance.

Effectiveness of Calcium Sulfate Scale Inhibitors in Spent Hydrochloric Acid/Seawater System

Previous results have reported the precipitation of calcium sulfate during matrix acid treatments when seawater was used to prepare HCl-based acid. Precipitations of calcium sulfate causes severe damage on the permeability of carbonate reservoirs and negatively impacts the performance of acid treatments. Typically, scale inhibitors are applied in the field to prevent the formation of calcium sulfate scale, and the object of this study is to evaluate the effectiveness of different types of scale inhibitors to inhibit the formation of calcium sulfate scale during the acid stimulation process. Scale inhibition efficiency was determined in batch tests under different temperatures (77 to 210°F) and different degrees of spent acid conditions. Sulfate ions were analyzed in the samples of the batch tests to detect the precipitations of calcium sulfate. Results showed that application of scale inhibitors can successfully mitigate calcium sulfate scale formation up to 210°F. At higher temperatures, the rate of calcium sulfate precipitation increased and the effectiveness of all types of scale inhibitors decreased greatly. Most of the scale inhibitors were not effective in acidic conditions and some of the scale inhibitors even precipitated out of the solution in the presence of high concentration of calcium ions. Methylene phoshponic acid scale inhibitor was the most effective one under various experimental conditions. The findings in this study provided information for better calcium sulfate scale control under acid stimulation conditions.

Phase equilibrium of CaSO4–Ca(OH)2–H2O system

In order to provide the theoretical guidance for applying the neutralization method to treatment of heavy metals wastewater with high concentration of sulfate, and to better understand the mechanism of calcium sulfate scale formation, the equilibrium solubility data of CaSO4–Ca(OH)2–H2O system at 298.15 K were theoretically calculated via the Pitzer semi-empirical ion-interaction theory, and determined experimentally by the optical method combining with X-ray diffractometry, and the calculated and determined phase diagrams of CaSO4–Ca(OH)2–H2O system were plotted and compared. Physical definition of each area was studied, and the physical law of characteristic point and line was explained in detail. Adjusting the pH value of neutralization-hydrolysis solution depended on the SO42- concentration in the system. And interaction characteristics between the solubilities of CaSO4(s) and Ca(OH)2(s) were found out.

The Prediction of Calcium Carbonate and Calcium Sulfate Scale Formation in Iranian Oilfields at Different Mixing Ratios of Injection Water with Formation Water

This article presents the prediction of calcium carbonate and calcium sulfate scale formation by water injection in oilfields at different mixing injection water-to-formation water ratios. The experimentally measured chemical analyses of formation water and injection water were input to the OLI ScaleChem model to determine the tendency of scale formation. The scaling tendency of CaCO3 and CaSO4 at reservoir temperatures and pressures is presented. This model has been applied to investigate the potential of calcium carbonate and calcium sulfate scale precipitation in Iranian oilfields in onshore and offshore fields as a method of secondary recovery or reservoir pressure maintenance.

Prevention of calcium sulfate formation in seawater desalination by ion exchange

In mechanical vapor compression (MVC) desalination, high operating temperatures (>120°C) allow for high heat transfer coefficients and reduced compressor size, both of which lower total capital costs. To prevent formation of calcium sulfate scale on high-temperature desalination heat exchangers, the inverse solubility of calcium sulfate requires high sulfate removal. To selectively remove sulfate from seawater, a weak-base anion-exchange resin (Relite MG 1/P) was used. In synthetic seawater, the resin shows high sulfate selectivity. Conveniently, the exhausted resin can be regenerated with concentrated acidified (pH 4) blowdown brine from the desalination heat exchanger. Using the same exhaustion and regeneration times, high desalination concentration factors increase chloride concentrations in the blowdown brine, which allows for slower regenerant flow rates thereby increasing regeneration efficiency and sulfate removal. Using a high concentration factor helps regeneration; however, this must be balanced...

Investigation into the effects of phosphonic inhibitors on the formation of calcium sulfate scales

The effects of several phosphonic additives on the formation of calcium sulfate scale on metal surface in a flow system were investigated thoroughly using multiple pipe flow system. Their chemical structure, concentration and run time are to be the main factors that influence the inhibitory capability of these anti-scalants. The relationships between these factors and the scale rate were established. The Langmuir adsorption isotherm is applied to predict the critical concentrations above which complete inhibition of scaling will occur. The inhibition efficiency order of the investigated organic additives is found as follows:EDTP > NTMP > NDPA > HEDP> NPDA, which corresponds to the number of phosphonate groups that the additives possess.

Effects of Process Parameters on Gypsum Scale Formation in Pipes

AbstractScaling often leads to a series of technical and economical problems in industrial plants and equipments by blocking water flow in pipes or limiting heat transfer in heat exchangers. While most contemporary studies are focusing on crystallization at heat‐exchanger surfaces and scaling on nanofilters in desalination plants, very little work has been done investigating scale formation on pipe and vessel walls. A comprehensive investigation of the effects of various process parameters in controlling the formation of calcium sulfate scale in pipes was undertaken. Supersaturation ratio, run time, and operational hydrodynamics were altered systematically to determine their influence on the scale growth rate. The results confirmed that the deposition of gypsum on pipe walls was significantly affected by these process parameters.

Maleic acid based scale inhibitors for calcium sulfate scale inhibition in high temperature application

In anhydrite rich reservoir rock, calcium sulfate is one of the dominant scale components which unlike carbonate scale are not easily removable by acid or dissolver treatment. To inhibit calcium sulfate scale formation in high temperature producing brine water systems, maleic acid–acrylic acid and maleic acid–acrylamide copolymers of appropriate molecular weight were synthesized and characterized and inhibition efficiency of the copolymers was tested at static and dynamic conditions. Their iron dispersing ability measured through UV spectroscopy is found to be excellent and their biocidal activity investigated through agar culture and serial dilution technique is almost insignificant. XRD and SEM analyses proved the morphological changes of the calcium sulphate scale due to strong inhibition action.

Evaluation of synthesized antiscalants for cooling water system application

Mineral scales are formed in cooling water systems and they cause heat transfer problems. This study has been carried out to reduce the carbonate and sulphate scales of calcium. To inhibit the scale formation in cooling water systems, polyacrylic acid was synthesized, characterized and the ability of the polymer to mitigate the calcium carbonate and calcium sulphate scale formation was tested through chemical screening and electrochemical impedance techniques. X-ray diffraction (XRD) and scanning electron microscope (SEM) studies were performed to understand the morphological changes of the scales in the presence of the polymer. The gelation and iron dispersion ability of the polymer were also noted. The synthesized polyacrylic acid was compared with the commercial product AQUASUPER B99, which is basically a polyacrylamide. It was observed that this polyacrylic acid could be used for the cooling water applications. Among the two inhibitors, polyacrylic acid shows slightly better antiscaling properties even at higher temperatures and pH for both CaCO 3 and CaSO 4 scales compared to the commercial product.