Brine Composition Research Articles

Source and Origin of Subsurface Brine of the Kongquehe Sag Area in Western Lop Nur, China

The Kongquehe Sag, located in the western Lop Nur, has abundant pore subsurface brine. In order to study the source and origin, we tested and analyzed the hydrochemical composition and stable isotopes of the subsurface brine. The findings reveal that the brine exhibits a moderate to low degree of mineralization, with values ranging from 50.50 g/L to 91.14 g/L. The stable isotope compositions of unconfined and confined waters are different, with the mean values of δD being −8.00‰ and −51.75‰ and the mean values of δ18O being 10.08‰ and −6.01‰. These values are indicative of an intense evaporative environment prevalent in the Kongquehe Sag area. Furthermore, the 87Sr/86Sr ratios vary between 0.710642 and 0.710837, and δ34S values range from 9.2 to 10.7. These data suggest the long-term evolution of sulfur substances, predominantly through dissolution and sedimentation processes, with minimal influence from redox reactions. The data garnered from this research not only offer a novel perspective of the insights gained into the hydrochemical characteristics and the stable isotope signatures of the brines in the Kongquehe Sag area but also enriches the theoretical framework concerning the source and origin of subsurface brines, potentially informing future exploration strategies.

Breunnerite grain and magnesium isotope chemistry reveal cation partitioning during aqueous alteration of asteroid Ryugu

Returned samples from the carbonaceous asteroid (162173) Ryugu provide pristine information on the original aqueous alteration history of the Solar System. Secondary precipitates, such as carbonates and phyllosilicates, reveal elemental partitioning of the major component ions linked to the primordial brine composition of the asteroid. Here, we report on the elemental partitioning and Mg isotopic composition (25Mg/24Mg) of breunnerite [(Mg, Fe, Mn)CO3] from the Ryugu C0002 sample and the A0106 and C0107 aggregates by sequential leaching extraction of salts, exchangeable ions, carbonates, and silicates. Breunnerite was the sample most enriched in light Mg isotopes, and the 25Mg/24Mg value of the fluid had shifted lower by ~0.38‰ than the initial value (set to 0‰) before dolomite precipitation. As a simple model, the Mg2+ first precipitated in phyllosilicates, followed by dolomite precipitation, at which time ~76−87% of Mg2+ had been removed from the primordial brine. A minor amount of phyllosilicate precipitation continued after dolomite precipitation. The element composition profiles of the latest solution that interacted with the cation exchange pool of Ryugu were predominantly Na-rich. Na+ acts as a bulk electrolyte and contributes to the stabilization of the negative surface charge of phyllosilicates and organic matter on Ryugu.

A complementary eco-friendly approach to heavy metal removal from wastewater/produced water streams through mineralization

With the world's ever-increasing population, portable water needs have significantly increased. This has put enormous pressure on the limited supply of freshwater around the globe and has necessitated the development of water treatment technologies that would convert saline waters into potable water for domestic and industrial uses. As saline water is treated for usage, so is wastewater generated from domestic and industrial processes. More prominently, another wastewater source is produced water consequent to oil production. Wastewater and produced water are similar in that they are both high in pollutants (heavy metals), which in discharge streams need to be kept within a threshold. The fact that heavy and rare earth metals linked to the produced water cannot be completely removed by state-of-the-art technologies is even more concerning. Thus, a complementary technology must be developed for this reason. This study investigates the mineralization of water-polluting heavy metals. The approach adopted involves the exposure of contaminated water to atmospheric or captured CO2 and the use of additives to achieve the removal. To gain a deeper understanding of how these innovative efforts function, the study also looked into the mechanism used to eliminate the heavy metals. The findings show that heavy metals in produced water and industrial effluent can be precipitated and immobilized to remove them. More so, this is made possible by the infusion of heavy metals into the crystal structures of precipitates like aragonite, calcite, and halite. Furthermore, the mechanism of the heavy metal removal involves their dehydration, immobilization and precipitation. Additionally, DFT calculations were utilized to support the experimental results by shedding light on the heavy metal hydration's ground-state structures and how EDTA chelates the heavy metals and enhances the process kinetics. The study's findings show how this strategy complements the most advanced wastewater treatment method in terms of increasing its efficiency and water security and safety. More so, as this is a pioneering effort, the optimum concentration of chelating agent and route (atmospheric or captured CO2) must be determined on a case-to-case basis for field implementation. Furthermore, the limitation of this study is that the efficiency of heavy metal removal may differ based on the starting brine composition, thus, optimization must be conducted beforehand.

Artificial neural network framework for the selection of deep eutectic solvents promoted enhanced oil recovery by interfacial tension reduction mechanism

Estimation of interfacial tension (IFT) and % reduction in IFT of Brazil and China regions’ heavy crude oil is employed by Artificial Intelligence (AI) led frameworks. The uniqueness of proposed approach lies in using AI frameworks that are constructed using Artificial Neural Network (ANN) and meta-heuristic algorithms i.e. Genetic Algorithm (GA) and Grey Wolf Optimization (GWO) forms three AI frameworks namely ANN, ANN-GA, and ANN-GWO is employed for IFT estimation of heavy oil and deep eutectic solvent-brine interface. The hyper-parameters of the frameworks are trained, validated, and tested over 18228 IFT data points obtained from the Omani heavy crude oil. The intermolecular interactions between oil, brine, and DES are obtained by generating surface segments in COnductor like Screening MOdel for Real Solvent (COSMO-RS) framework. The composition of brine, mole ratio of oil, DES, and temperature are other input parameters for AI model. The IFT estimation leads to the selection of 3 hydrophilic DESs capable of greater than 75 % IFT reduction and 14 hydrophilic DESs capable of 50–75 % IFT reduction. ANN-GWO scores best AI framework among 3 whereas ANN-GA fails to estimate IFT reduction greater than 50 %. Analysis of IFT with respect to mole fraction reveals the most suitable range of DES addition for IFT reduction.

CO2-brine interactions in anhydrite-rich rock: Implications for carbon mineralization and geo-storage

The utilization of subsurface geologic media for carbon capture and storage through mineralization has been recognized as a reliable approach. However, less attention has been given to anhydrite rock type for CO2 mineralization and storage. Anhydrite-rich rock formations, commonly found in various geological settings, have the potential to serve as natural carbon sinks through the mineralization of CO2. Therefore, this study aims to investigate the mechanisms and potential of anhydrite-CO2-brine interactions for carbon storage. The experimental approach involved exposing anhydrite-rich rock to supercritical CO2-brine environments under varying conditions of fluid composition. Mineral transformation of an outcrop anhydrite-rich rock sample in static reactor under subsurface conditions of elevated temperature (60 °C) and pressure (104 bar), in the absence and the presence of SrCl2 was conduct for a one-month period. Mineralogical and geochemical analyses, including, solution analyses, X-ray fluorescence, X-ray diffraction, micro-computed tomography, and mechanical properties were conducted to examine the changes in the composition and rock structure resulting from the interactions. The experimental reactions revealed that anhydrite undergoes mineral transformation upon exposure to supercritical CO2-saturated brine to form stable minerals including calcite, dolomite, magnesite, and strontianite, which contributes to the potential for long-term storage of CO2 in the subsurface geologic media. The efficiency and extent of carbon mineralization were found to be influenced by brine composition. These findings contribute to the understanding of the potential of these formations for carbon storage, opening avenues for further research and the development of effective carbon capture and storage strategies.

Influence of Reservoir Salinity, Mineralogy, Temperature, and Pressure on Geochemical Hydrogen Loss in Depleted Carbonates

Summary Underground hydrogen storage (UHS) is a cost-effective and safer system vital for the growth of the hydrogen market and its role as an essential transitional fuel. Presently, depleted hydrocarbon reservoirs (DHR) account for more than 75% of all UHS sites due to their higher prevalence and readiness for use. However, hydrogen (H2) loss primarily due to abiotic interactions poses a significant challenge to the integrity of DHR sites, and while the underlying conditions have been investigated in some studies, the conclusions have been inconsistent, particularly for carbonate reservoirs. In this study, we analyzed the impact of reservoir physical and chemical parameters, (i.e., salinity, mineralogy, temperature, and pressure) on H2-brine-mineral interactions and the extent of H2 loss in carbonate formations. Static batch simulations were performed using PHREEQC and MATLAB® for a 1-year storage cycle period with three different brine and rock samples at 50–130°C and 15–30 MPa. The results showed that the dissociation of H2 and formation of CH4 and H2S increased with increasing temperature, at a two times higher rate compared to pressure. Also, markedly, in various brine compositions and reactive mineralogy, a 20% or less H2 loss could be attained in temperatures <50°C and 115–130°C, with pressure below 17 MPa; meanwhile, the pressure condition 18 MPa and greater (at 50°C) would risk at least 50% loss, with >86% from 19 MPa. Second, H2 loss increased to 80% after about 50 days for all the brines, and pressure and temperature conditions in the mineral sample with the largest composition of reactive minerals (i.e., pyrite, anhydrite, etc.) suggested a 50% loss risk in such mineralogy during the storage cycle period of about 1 month. Lastly, in the mineral sample with >90 wt% calcite and 0–2 wt% reactive minerals composition, H2 molality increased at least fourfold on average across the storage period and reservoir brine/temperature/pressure conditions. This result further indicates that reactive mineralogy has a more significant effect on the stability of hydrogen relative to temperature and pressure in a carbonate UHS formation. In summary, the findings suggest that a minimal reactive mineral composition, 100°C or higher, and 17 MPa or lower constitutes a set of reservoir physical and chemical conditions with the potential for a limited risk of H2 loss (<20%) in carbonate DHR. However, the extension of the present work to the dynamic UHS conditions is necessary to further ascertain these conclusions.

Importance of Fluid/Fluid Interactions in Enhancing Oil Recovery by Optimizing Low-Salinity Waterflooding in Sandstones

Low-salinity waterflooding/smart waterflooding (LSWF/SWF) is a technique involving the injection of water with a modified composition to alter the equilibrium between rock and fluids within porous media to enhance oil recovery. This approach offers significant advantages, including environmental friendliness and economic efficiency. Rock/fluid mechanisms such as wettability alteration and fines migration and fluid/fluid mechanisms such as a change in interfacial tension and viscoelasticity are considered active mechanisms during LSWF/SWF. In this study, we evaluated the effect of these mechanisms, by LSWF/SWF, on sandstones. To investigate the dominant mechanisms, coreflooding studies were performed using different injected fluid composition/salinity and wettability states. A comparative analysis of the recovery and mobility reduction factor was performed to clarify the conditions at which fluid/fluid mechanisms are also effective. Our studies showed that wettability alteration is the most dominant mechanism during LSWF/SWF, but, for weak oil-wet cases, optimizing brine compositions may activate fluid/fluid mechanisms. Brine composition significantly influences interface stability and performance, with sulfate content playing a crucial role in enhancing interface properties. This was observed via mobility behavior. A comparative analysis of pressure differentials showed that fines migration may act as a secondary mechanism and not a dominant one. This study highlights the importance of tailored brine compositions in maximizing oil recovery and emphasizes the complex interplay between rock and fluid properties in enhanced oil recovery strategies.

Kinetics of In-Situ Calcium Magnesium Carbonate Precipitation and the Need for Desulfation in Seawater-Flooded Carbonate Reservoirs

Summary Mixing of incompatible injection and formation brines leads to the deposition of inorganic sulfate scales such as barite, celestite, and anhydrite in and around production wells. This process is well documented in seawater-flooded clastic reservoirs. One technique to avoid the resulting formation damage is to remove sulfate from seawater before injection using nanofiltration; however, this process is costly. We identify in this paper that it may not always be necessary in higher-temperature carbonate reservoirs. In this paper, we describe the use of reactive transport reservoir simulation to investigate the impact of carbon dioxide (CO2) partitioning and changes in pH, ionic concentrations, and temperature on carbonate reactivity and the sulfate scaling risk in waterflooded carbonate reservoirs. Dissolution and precipitation of calcite, dolomite, gypsum, anhydrite, barite, and celestite are all modeled and found to be coupled through (various) common ion effects. The produced brine compositions are used to calculate the saturation ratios (SRs) and mass of precipitate that may form in the production system. Sensitivity to mineral reaction kinetics, particularly for the dolomite reactions, is accounted for. Results identify that there is a strong relationship between calcite dissolution and dolomite (or other calcium/magnesium carbonate mineral) precipitation reactions, which drive each other and are affected by the availability of CO2 in the residual oil phase. This evolves over time, and as the thermal front propagates, impacts the concentration of calcium and magnesium in the brines traversing the reservoir. Temperature changes around the injection wellbore impact CO2 and mineral solubilities. The concentration of calcium in the displaced brine mix is thus determined more by contact with rock and temperature than by mixing between injection and formation brines. Depending on location relative to the thermal front, this may lead to gypsum or anhydrite precipitation, thereby stripping sulfate out of the injection brine. Thus, the sulfate scaling risk at the production wells is significantly reduced by this sulfate depletion process: The sulfate is stripped out of the seawater as it warms up in the reservoir before it mixes extensively with the formation water and significantly before any mixture of the two brines reaches the production zone. Thus, any loss of permeability is restricted to deep within the reservoir, where the pore volume (PV) that can accommodate mineral precipitation is very large. In this work, we identify that for carbonate reservoirs above 90–100°C, stripping of sulfate due to coupled mineral reactions may reduce or eliminate the need for use of a sulfate reduction plant (SRP). The process is modeled for the first time, accounting for the impact of CO2 partitioning and thermal front propagation. Knowledge of the kinetics of calcium/magnesium carbonate precipitation is shown to be critical in predicting the extent of sulfate depletion.

СОЛЕВОЙ КОНЦЕНТРАТ ДЛЯ МИНЕРАЛИЗАЦИИ БУРОВЫХ РАСТВОРОВ

A method is described for preventing the formation of cavities when drilling wells in the intervals of occurrence of water-soluble minerals through the use of mineralized drilling fluids. The composition of the natural brine of the Znamenskoye deposit and the salt concentrate obtained from it by spray dry-ing, suitable for mineralization of drilling fluids, is given

Decoupling of Cu and Zn in sediment-hosted base metal deposits: Evidence from LA-ICP-MS analyses of fluid inclusions and trace elements in minerals at Baiyangping, China

Copper and lead–zinc mineralization in basinal rocks worldwide commonly shows distinct spatiotemporal zonation. The Baiyangping deposit in the Lanping Basin, southwest China, is a large sediment-hosted polymetallic deposit that shows clear and pronounced zoning of Cu versus Pb-Zn mineralization. Here, we analyzed trace elements in pyrite and sphalerite and fluid inclusions in sphalerite, celestine, quartz, and dolomite to seek insights into the origins of the ore-forming fluids and the processes that govern the separation of Cu- from Zn-rich ores. We show that while the later Zn-rich mineralization is characterized by fluid inclusions showing typical hallmarks of basinal brine composition (low homogenization temperature < 230 °C, high salinity > 20 wt% NaCl eq., dominated by Na-K-Ca-Mg chlorides), the earlier Cu-rich mineralization shows markedly distinct composition that more closely resembles deeply-circulated water that has equilibrated with crystalline basement rocks (higher homogenization temperature of 210–280 °C, variable but lower salinity of ∼ 5–15 wt% NaCl, dominated by Na-K-Li chlorides). Pyrites formed during the earlier Cu-rich stage show elevated Cu, Co, Sb and Zn, while pyrites formed during the later Pb-Zn stage are more enriched in As, Pb and Mn. We interpret that the earlier-formed Cu-rich ores were deposited by deeply sourced fluids that ascended along basement-penetrating reverse faults, whereas the later Zn-rich ores were formed by subsequent circulation of fluid from within the basin, whose flux was promoted by shallower strike-slip faults. Hence, the two ore types reflect discrete pulses of chemically distinct hydrothermal fluids. We suggest that the evolving structural controls and fluid pathways during prolonged ore formation allowed sequential pulses of fluids that had acquired different metal budgets by equilibration with different sources. We suggest that this type of two-step process may be more common in sediment-hosted base metal deposits than single-fluid cooling sequential order of precipitation.

Surface charge change in carbonates during low-salinity imbibition

Optimizing the injection water salinity could present a cost-effective strategy for improving oil recovery. Although the literature generally acknowledges that low-salinity improves oil recovery in laboratory-scale experiments, the physical mechanisms behind it are controversial. While most experimental low-salinity studies focus on brine composition, this study investigated the influence of carbonate rock material on surface charge change, wettability alteration, and spontaneous imbibition behavior. Zeta potential measurements showed that each tested carbonate rock material exhibits characteristic surface charge responses when exposed to Formation-water, Seawater, and Diluted-seawater. Moreover, the surface charge change sensitivity to calcium, magnesium, and sulfate ions varied for the tested carbonate materials. Spontaneous imbibition tests led to high oil recovery and, thus, wettability alteration towards water-wet conditions if the carbonate-imbibing brine system’s surface charge decreased compared to the initial zeta potential of the carbonate Formation-water system. In the numerical part of the presented study, we find that it is essential to account for the location of the shear plane and thus distinguish between the numerically computed surface charge and experimentally determined zeta potential. The resulting model numerically reproduced the experimentally measured calcium, magnesium, and sulfate ion impacts on zeta potential. The spontaneous imbibition tests were history-matched by linking surface charge change to capillary pressure alteration. As the numerical simulation of the laboratory-scale spontaneous imbibition tests is governed by molecular diffusion (with a time scale of weeks), we conclude that molecular diffusion-driven field scale wettability alteration requires several hundred years.

Hydrochemical Characteristics and Evolution of Underground Brine in Lop Nur, Northwestern China

AbstractLop Nur is located at the eastmost end of the Tarim Basin in Xinjiang, Northwestern China. This study reviews the hydrochemical characteristics and evolution of underground brine in Lop Nur, based on analytical data from 429 water samples (mainly brine). It is found that in the NE–SW direction, from the periphery to the Luobei sub‐depression, while the hydrochemical type varies from the sodium sulfate subtype (S) to the magnesium sulfate subtype (M), the corresponding brine in the phase diagram transfers from the thenardite phase (Then) area, through the bloedite phase (Blo), epsomite phase (Eps), picromerite phase (Picro), finally reaching the sylvite phase (Syl) area. As for the degree of evolution, the sequence is the periphery &lt; Luobei horizontally and the overlying glauberite brine &lt; the underlying clastic brine vertically. It is concluded that the oxygen and hydrogen isotopic compositions of the brine have evidently been affected through the effects of evaporation and altitude, as well as the changes in local water circulation in recent years. Boron and chloride isotopic compositions show that the glauberite brine is formed under more arid conditions than the clastic one. The strontium isotopic composition indicates that the Lop Nur brine primarily originates from surface water; however, deep recharge may also be involved in the evolution of the brine, according to previous noble gas studies. It is confirmed that the brine in Lop Nur has become enriched with potassium prior to halite precipitation over the full course of the salt lake's evolution. Based on chemical compositions of brine from drillhole LDK01 and previous lithological studies, the evolution of the salt lake can be divided into three stages and it is inferred that the brine in Lop Nur may have undergone at least two significant concentration‐dilution periods.

Authigenic quartz reveals the triple oxygen isotope composition and diagenetic temperature of saline brines

Triple oxygen isotope compositions of authigenic minerals are an emerging tool for the reconstruction of fluid temperatures and the fluid isotopic composition. In this study, we analyzed euhedral authigenic quartz crystals from a halite deposit of the Upper Permian Zechstein evaporitic basin for their triple oxygen isotope composition using laser fluorination isotope ratio mass spectrometry. In the triple oxygen isotope space, additional information, such as the triple oxygen isotope composition of the ambient water, provides insights into equilibrium conditions during quartz formation that cannot be identified from δ18O alone. The triple oxygen isotope composition of authigenic quartz shows, that single oxygen isotope (δ18O) thermometry is not applicable for samples from evaporitic environments, where the fluids' δ18O deviates from dynamic oxygen isotope equilibrium. By combining the Craig and Gordon evaporation model with H2O – SiO2 triple oxygen isotope equilibrium fractionation, we reconstruct the formation temperature of authigenic quartz and the triple oxygen isotope composition of the marine-derived saline brine pore fluid in equilibrium with the quartz. We obtain temperatures of 90 to 130 °C that is interpreted as crystallization temperatures of microcrystalline quartz in pore fluid of halite during burial diagenesis. The triple oxygen isotope composition of authigenic quartz from evaporitic environments is suited as a geochemical tracer for fluid oxygen isotope compositions and ancient fluid or diagenetic temperatures.

Application of a new brine of sprouted grains for delicatessen products from horse meat, beef, and pork

The main task of the meat processing industry is to produce meat products as the primary source of animal protein that ensures the vital activity of the human body in the necessary volumes, high quality, and a diverse assortment. Providing the population with high-quality food products that are biologically complete, balanced in the composition of the primary nutrients, and enriched with target physiologically active components is one of the most priority scientific and technical problems to be solved. In this regard, a recipe for a new brine from sprouted grains for delicatessen products from horse meat, beef, and pork was developed. The composition of the new brine includes flavoring and aromatic ingredients, juice of sprouted grains, and juices of raw vegetable materials. The viscosity of horse meat, beef, and pork during massaging was studied. Thermodynamic parameters such as water activity and moisture binding energy of horse meat, beef, and pork using a new brine were studied. The data analysis shows that the values of the “aw” indicator and the moisture binding energy in the experimental samples of meat products are higher than in the control samples. Studies have found that with an increase in the activity of water and the moisture binding energy, the tenderness of finished delicatessen meat products with a new brine increases. As a result, it was found that the maximum amount of brine in horse meat is retained at 160 minutes of continuous massaging, in beef – at 130 minutes, in pork – at 120 minutes of mechanical processing.

Hydroclimate of the Messinian Salinity Crisis constrained from paleo-water triple oxygen, hydrogen, and strontium isotopes

Giant evaporite deposits formed during the Messinian Salinity Crisis (MSC) in the Mediterranean Sea during the upper Miocene. The primary cause is a restricted Atlantic-Mediterranean connection, but the detailed hydroclimate evolution of this event is still a matter of debate. Here we reconstruct the triple oxygen and hydrogen isotopic composition of paleo brines from structurally bonded water in Messinian gypsum from Cyprus. A two-stage evaporation model is constructed to best approximate the hydrological conditions at which Messinian gypsum formed in marginal basins of the Mediterranean Sea. Subsequently, hydroclimatic parameters like paleo relative humidity (RH) are modelled using an iterative curve fitting isotope model approach. The results of our limited dataset reveal a slightly lower RH during the third compared to the second stage of the MSC. This apparent drop in RH is consistent with previous observations from the literature.Besides absolute values of RH, our model allows reconstructing the triple oxygen and hydrogen isotopic composition of the open Mediterranean Sea. This provides an estimate for the proportions of continental water vs. Atlantic seawater flowing into the basin, serving as a proxy for the size of the strait of Gibraltar. The model implies a continental water fraction of around 75–81 % both for the second and third stage of the MSC. In addition, we determined the 87Sr/86Sr of our samples to: i) confirm their stratigraphy; and ii) estimate the relative proportion of continental water vs. Atlantic seawater entering the Mediterranean using Sr mass balance calculations. The combined oxygen and Sr isotope records indicate a persistent connection to the Atlantic supporting the hypothesis that the striking drop in 87Sr/86Sr at the beginning of MSC stage 3 is mainly related to an increased contribution of continental water with low 87Sr/86Sr and high Sr concentrations from the Paratethys. Our results show that the combination of triple oxygen, hydrogen, and Sr isotope data provides a powerful tool to disentangle paleo-hydroclimate even in such complicated hydrological settings as the Mediterranean Sea during the MSC.

Prediction of clog time of amorphous silica in the pipes of the wells from Los Humeros geothermal field – A new geochemical model along with a computational algorithm

The primary objective of this article is to introduce a physicochemical model along with a computational algorithm that is valuable for quantifying the occurrence of silica scaling and fouling within geothermal production wells. This model utilizes two-phase flow parameters, temperature and pressure profiles, as well as brine composition to forecast the timing of production pipe constriction caused by amorphous silica deposition over time. The model is applicable to systems with temperatures ranging from 270°C to 305°C, vapor pressures ranging from 55 to 93 bars, and enthalpies ranging from 1189 kJ/kg to 1400 kJ/kg. The predictive model was calibrated using data gathered from six distinct wells within the Los Humeros geothermal field in Mexico, and subsequently, it was applied to forecast outcomes in two additional wells. When the conditions of temperature, pressure, and enthalpy remain relatively constant throughout the production process, the model developed in this study accurately predicts the times at which a certain percentage of pipe sealing occurs in wells with high volumetric fractions of liquid (εl&gt;0.5) and temperatures between 270°C and 305°C. The prediction error is less than 3%.

МИНЕРАЛИЗОВАННЫЕ БУРОВЫЕ РАСТВОРЫ

A method is described for preventing the formation of cavities when drilling wells in the intervals of occurrence of water-soluble minerals through the use of mineralized drilling fluids. The composition of the natural brine of the Znamenskoye deposit and the salt concentrate obtained from it by spray dry-ing, suitable for mineralization of drilling fluids, is given

A triple-layer based surface complexation model for oil-brine interface in low-salinity waterflooding: Effect of sulphate interaction with carboxylic and basic groups, pH and temperature

The determination of the electrokinetic properties of oil-brine interface is necessary to understand and evaluate the low-salinity waterflooding (LSWF) effect on enhanced oil recovery (EOR). Among the least understood aspects are the effect of SO42- interaction with the polar oil components, and temperature on the zeta-potential of the oil-brine interface. Therefore, a novel triple-layer based surface complexation model (SCM) was developed to capture the effect of SO42- interaction with both carboxylic and amine sites. One of the key uncertainties in a SCM is the surface site density of the functional groups. In this regard a Monte-Carlo based optimization algorithm for determination of these parameters as a function of pH and brine composition was devised. The SCM was successfully validated with the published zeta-potential data and was further used to evaluate the electrokinetic properties of oil-brine interface in a wide range of temperature and pH and to unravel the reason behind positive oil-brine zeta-potential at high ionic strength and pH, as reported for some crude oils in the literature. A sensitivity analysis was conducted to determine the relative contribution of site densities of carboxylic and amine groups as well as the capacitances to the oil-brine zeta-potential. The results clearly show that the interaction of SO42- ions with both carboxylic and particularly amine groups affects the surface potential significantly, thus should not be underestimated. Presence of SO42- in Na2SO4 and MgSO4 brines results in an incremental negative zeta-potential compared to that in NaCl and MgCl2 brines; confirming its role in changing charge distribution in the Stern layer. If these interactions are ignored, it should be compensated for by artificially adjusting concentration of positively and neutrally charged surface species. One important finding is that, despite the common perceptions, the site density of the oil polar groups is not constant and should be changed as pH and brine composition are changed and linear correlations between acid and base number and site densities are not justifiable. It is also found that zeta-potential tends to shift to neutral values as temperature is elevated due to the increased adsorption of divalent cations to the interface. The findings of this paper can help predict the zeta-potential of oil-brine interface more accurately and explain the observed trends in the experimental data.

Sustainable energy recovery from salt-lake brines through a novel selective reverse electrodialysis process

The salinity gradient energy (SGE) in salt-lake brines can be exploited as a sustainable energy source through reverse electrodialysis (RED). However, the composition of brines is notably intricate. In order to avoid the adverse effects of multivalent cations on RED in brines, we introduced a novel selective reverse electrodialysis (SRED) here. The results demonstrate that when increasing the salinity ratio between high and low concentration feeds (HCFs, LCFs) from 20 to 60, the SRED maximal maximum power density (Pd,max) improves from 0.069 to 0.109 W/m2. The feed salinity has less obvious effect on SRED. Moreover, the role of Mg2+ on the adverse effects is regulated. The maximal Pd,max of SRED is 1.13 ∼ 1.23 times higher than that of the conventional RED at the Mg2+ concentrations of 4861.00 ∼ 14583.00 ppm in HCFs and 40.51 ∼ 121.53 ppm in LCFs. This suggests that SRED is a feasible and efficient strategy for capturing SGE in salt-lake brines.

Impact of engineered water in modulating the wettability of oil–brine–rock system for improved oil recovery

AbstractLow salinity water injection stands as a progressive method for enhanced oil recovery, representing a current focus of extensive research. Understanding wettability alteration in crude oil is hindered by its intricate nature, posing a challenge for researchers. In order to better understand wettability alteration and underlying phenomena in an oil–brine–rock system, a fundamental study was carried out using pure hydrocarbon (aliphatic: n‐heptane; aromatic: toluene) and crude oil on quartz surface against engineered water consist of monovalent (NaCl) and divalent (MgSO4) salts in various compositions (NaCl:MgSO4: 100:0; NaCl:MgSO4: 0:100; NaCl:MgSO4: 75:25; NaCl:MgSO4: 50:50; NaCl:MgSO4: 25:75). The variables under investigation include temperature (25 to 65°C), pure hydrocarbons (toluene, n‐heptane), crude oil (Indian offshore), and brine (B1 to B5) with concentration (0 to 20,000 ppm). The findings show that when brine solution contains solely NaCl salt at a concentration of 2000 ppm, n‐heptane exhibits a minimum contact angle on quartz plate. Contrarily, toluene exhibits a low contact angle with a brine solution that only contains MgSO4 salt at a concentration of 2000 ppm. The intriguing finding is that when monovalent and divalent salts are equal (NaCl:MgSO4: 50:50) in the brine, crude oil exhibits the smallest contact angle on quartz. Additionally, temperature and contact angle are directly related for all oil types. The optimal brine for achieving the minimum contact angle on quartz surface is (B1)2000 for n‐heptane, (B2)2000 for toluene, and (B4)2000 for crude oil for the current study. The study findings indicate that the alteration in wettability due to brine composition and salinity varies among different oil samples, characterized by purely aliphatic, aromatic, and mixed components, and it depends on the type of salt compositions. Higher salts concentration minimally affects n‐heptane but influences toluene and crude oil contact angles.