Search Results (41)

Natural lithium-bearing brines are gaining strategic importance as an alternative to traditional hard-rock deposits. Approximately 78% of the identified global lithium resources are hosted in hydromineral environments, including continental brines, oilfield formation waters, and geothermal fluids. The Shu–Sarysu sedimentary basin in southern Kazakhstan is one of the most extensive, yet poorly studied, brine provinces in Central Asia. This study provides a comprehensive hydrogeochemical characterization of lithium-bearing brines in the Moiynkum structural zone of the Shu–Sarysu basin, based on regional field sampling, multielement analysis, and GIS data integration. Water samples were collected from four deep gas production wells (perforation depths of 2029–2290 m) at the Ayrakty and Amangeldy fields. Analytical data demonstrate highly concentrated chloride–calcium–sodium brines with total dissolved constituent concentrations (TDS, calculated as the sum of analyzed ions) ranging from 140.1 to 272.1 g/L, with lithium content of 24.46–55.11 mg/L, strontium 680.5–1648.2 mg/L, rubidium 4.31–8.42 mg/L and cesium 0.317–0.420 mg/L. Piper and Durov diagrams classify the samples as highly evolved Na–Ca–Cl to Ca–Na–Cl formation brines typical of deep, long-residence sedimentary formation waters. Lithium enrichment is interpreted to reflect the combined influence of several processes: water–rock leaching of Li-bearing lithologies, evaporative concentration of ancestral brines, clay-mineral ion exchange, and possible deep fluid contributions, whose relative roles remain to be constrained by isotopic data. The compiled GIS-integrated database, combining new analytical data with archival hydrogeochemical records, delineates two promising lithium-bearing provinces and identifies priority areas for further exploration. The results indicate that the Shu–Sarysu Basin is a prospective region for further exploration of lithium-bearing formation waters in Kazakhstan. The recorded Li concentrations fall within the lower range of sedimentary-basin brines currently being evaluated for lithium extraction, although their economic and technological feasibility remains to be established. Full article

This study presents a hydrogeochemical assessment of oilfield formation waters from the Karazhanbas, Zhetybay, and Uzen oil fields in the Mangystau Region of Kazakhstan, with the aim of elucidating lithium distribution, identifying the geochemical factors controlling its accumulation, and providing a preliminary resource-oriented evaluation. The study investigated pH, total dissolved solids (TDS), ionic–salt composition, lithium (Li) concentration, and the relationships between Li, TDS, major cations, and geochemical ratios, including Ca/Li and Mg/Li. Major ions were determined using standard hydrochemical methods, while Li was analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES). The investigated waters were predominantly classified as chloride–calcium type according to their hydrochemical composition. In terms of TDS, the waters follow the sequence Uzen > Zhetybay > Karazhanbas, whereas Li concentrations follow the sequence Zhetybay > Uzen > Karazhanbas. The highest Li concentrations were detected in Zhetybay waters (1.40–1.85 mg/dm³); in Uzen waters, Li reached 1.51 mg/dm³; and in Karazhanbas waters, it ranged from 0.30 to 0.70 mg/dm³. The highest Mg/Li and (Na⁺ + K⁺)/Li ratios were characteristic of Uzen waters, indicating a more complex salt matrix. Compared with internationally reported lithium-enriched brines, the Mangystau formation waters contain relatively low Li concentrations and cannot currently be considered a commercially viable lithium source. The scientific significance of this study lies in establishing a regional hydrogeochemical baseline for oilfield formation waters and demonstrating that maximum mineralization does not necessarily correspond to the highest Li concentration. Full article

Corrosion and scaling critically threaten the safety and efficiency of oil–gas gathering stations. Through field inspections, water chemistry analysis, scale characterization, and corrosion simulation in Yanchang oilfield, this study identifies severe localized damage in key components—such as valves, bends, and injection pipelines—with service lives of only 1–2 years. Analysis of over 200 scale samples revealed that CaCO₃ (42 wt%) and CaSO₄ (23 wt%) were the predominant scale types. High salinity >56,000 mg/L, Cl⁻ >31,000 mg/L, and Ca²⁺ promote under-deposit pitting, galvanic corrosion (e.g., Cu–steel couples), and erosion-corrosion at high-velocity zones. Simulations based on OLI Analyzer Studio (a professional thermodynamic simulation software for electrolyte solution and high-salinity brine systems) reveal that the carbon steel (the primary material for the process pipelines and water injection pipelines in the studied oil–gas gathering and transportation stations) has a corrosion rate rising from 0.078 mm/year at 25 °C to 1.94 mm/year at 90 °C. Despite common use of coatings and cathodic protection, these measures often fail to address site-specific failure mechanisms. The study advocates a tailored mitigation strategy combining material compatibility, real-time water monitoring, optimized filtration, and component-level design. This integrated approach enhances asset reliability and operational safety in onshore oilfields. Full article

Mineral scale deposition remains a major flow-assurance constraint in oil and gas operations, especially in water-flooding and produced-water reinjection, where mixing between incompatible brines promotes super-saturation and precipitation of poorly soluble salts. This work introduces a novel extension of traditional methods used for modeling chemical inhibition and the predictive evaluation of oilfield scale-inhibitor molecules. A systematically optimized Two-Dimensional Quantitative Structure–Activity Relationship Model based on the k-Nearest Neighbors algorithm 2D-QSAR-KNN model was developed to quantitatively link molecular constitution of phosphonate inhibitors, brine chemistry, and operating factors with inhibition efficiency IE %. The optimized model achieved strong accuracy and generalization R²_train = 0.9182, R²_test = 0.9306, and R²_global = 0.9208 with low prediction errors RMSE_train = 4.7888%, RMSE_test = 4.5485%, and RMSE_global = 4.7421%. Median absolute errors remained minimal for the train set = 0.80%, and test set = 1.63%, and model stability was confirmed by high correlation with experimental IE % r = 0.94 and R²_train/R²_test ≈ 0.99, showing no sign of overfitting. Additionally, an inverse-2D-QSAR framework was applied to identify the optimal molecular descriptor profile expected to maximize inhibitory performance within normalized bounds, providing rational rules for next-generation inhibitor design. The findings highlight the practical value of QSAR-inspired AI modeling to accelerate molecule screening and dosage exploration prior to laboratory validation, supporting more cost-effective, interpretable, and environmentally aware sulfate-scale inhibition strategies under high-salinity reservoir conditions. Full article

Calcareous interbeds are widely developed in marine clastic sequences, where laterally continuous, tight calcareous interbeds act as critical controls on the formation of lithologic traps and the distribution of oil. However, the genetic mechanisms and development models of these interbeds, particularly under deep-burial conditions subject to complex fluid interactions, remain poorly understood. Using the Donghe Sandstone in the Hade Oilfield (Tarim Basin) as a case study, this paper investigates the genetic evolution of calcareous interbeds via an integrated approach combining core observation, thin-section petrography, scanning electron microscopy (SEM), stable isotope analysis, fluid inclusion microthermometry, and heavy fraction analysis. The results indicate that: (1) The carbonate cements within the interbeds are compositionally complex, dominated by calcite but characterized by a diagnostic assemblage of anhydrite, ferroan calcite, and ankerite. (2) During the depositional to shallow burial stages, seawater evaporation and meteoric freshwater influx led to the supersaturation of calcium-rich pore waters near the surface. This facilitated the precipitation of early cement assemblages, which are predominantly of freshwater origin and consist mainly of non-ferroan calcite nodules, dolomite, and anhydrite. (3) During the deep burial stage, the injection of high-salinity brines and organic acid decarboxylation triggered Thermochemical Sulfate Reduction (TSR). This process caused the extensive consumption of the pre-existing anhydrite and the formation of authigenic pyrite, followed by the tight occlusion of remaining porosity through the precipitation of late-stage ferroan calcite and ankerite. (4) In the broad slope setting, these tight calcareous interbeds constitute effective flow barriers, resulting in a stepped distribution of the oil–water contact. Within the reservoir compartments segmented by these interbeds, crude oil maturity exhibits a distinct inversion (i.e., higher maturity below the interbeds and lower maturity above), confirming the critical sealing capacity of the interbeds during hydrocarbon accumulation. Ultimately, this study establishes a genetic model coupling calcareous interbed development with deep-burial fluid alteration, providing new geological insights for predicting subtle traps in marine sandstone reservoirs. Full article

Bromine, as a strategic fundamental chemical raw material, is crucial for modern industry, but the traditional chlorine displacement method poses safety risks in oilfield brine development and faces challenges like resource depletion and inefficient utilization. Addressing the need for high-concentration bromine brine development in underground oilfields, this study developed an electrochemical oxidation-based chlorine-free bromine extraction technology. Leveraging the standard redox potential difference between Br⁻ and Cl⁻ (0.271 V), the effective potential window for selective Br⁻ oxidation was determined as 1.0–1.52 V (vs. SHE) via linear sweep voltammetry (LSV). Within this window, efficient and preferential oxidation of Br⁻ over Cl⁻ and OH⁻ was achieved. In simulated brine with high chloride and low bromide concentrations, a Br⁻ conversion rate of 92.3% was attained with no Cl₂ generation. The self-designed zero-gap electrolyzer with carbon cloth as the anode reduced the reaction time by over 75% compared to a traditional H-type cell, oxidizing over 90% of Br⁻ within 12 min. Kinetic studies revealed that the reaction follows first-order kinetics, with current intensity positively correlated with Br⁻ concentration. Investigation of coexisting ions revealed that low concentrations of Cl⁻ promote the reaction, while high concentrations exert inhibitory effects. CO₃²⁻ exhibits a weak promoting effect, and Ca²⁺/Mg²⁺ show negligible impact. Notably, organic matter (e.g., ethylene glycol) concentrations exceeding 80 mg/L substantially compromise bromine recovery efficiency. This technology provides a feasible solution for the safe and green development of high-concentration bromine resources and holds significant importance for the upgrading of the bromine chemical industry. Full article

In response to the complex drilling conditions in the carbonate reservoirs of the Tahe Oilfield, a brine-based solids-free drilling fluid system using oilfield-produced water was developed. Most existing solids-free drilling fluid systems are formulated with fresh water or low-mineralization water, which cannot maintain stability in the high-salinity, high-mineralization conditions of oilfield water. This study addresses this gap by systematically optimizing viscosifiers, fluid-loss control agents, and lubricants, enabling the use of highly mineralized produced water. The developed system maintains good rheological properties and fluid loss control even under challenging conditions. Laboratory tests show that the system, with POLY-V as the viscosifier, DEG-FLO and STAR-AM as fluid-loss agents, and ATV-SLIP as the lubricant, exhibits stable performance under the high-temperature, high-salinity conditions typical of the Tahe Oilfield, with limited performance degradation. Full article

Lithium has emerged as a critical energy metal due to its indispensable role in batteries, aerospace applications, new energy vehicles, and large-scale energy storage systems. The accelerated growth of electric mobility and renewable energy storage has led to a substantial increase in lithium demand, thereby exacerbating the prevailing global supply–demand imbalance. To address this challenge, it is imperative to diversify lithium resources and to advance extraction technologies that are both efficient and sustainable. In comparison with conventional hard-rock deposits, liquid resources such as salt lake brines, oilfield brines, and deep-well brines are gaining attention owing to their broad distribution, abundant reserves, and advantages of reduced land use, lower water consumption, and lower carbon emissions. This work presents a critical review of current lithium recovery strategies from brines, including precipitation, solvent extraction, adsorption, nanofiltration/electrodialysis, and electrochemical methods. Each approach is critically evaluated in terms of Li/Mg selectivity, extraction efficiency, operational stability, and environmental compatibility. Precipitation processes offer simplicity but suffer from low Li recovery and high chemical consumption; solvent extraction achieves high selectivity but faces phase and reagent loss; adsorption using Mn-based sieves yields high capacity with good regeneration stability, whereas membrane and electrochemical systems enable continuous lithium recovery with reduced energy input. Distinct advantages and existing gaps are systematically summarized to provide quantitative insights into performance trade-offs among these pathways. Key findings highlight that organophosphorus–FeCl₃ systems and Mn-based lithium-ion sieves show the best trade-off between selectivity and regeneration stability, whereas emerging membrane–electrochemical hybrids demonstrate promise for low-energy, continuous lithium recovery. The prospects for future development highlight highly selective functional materials, integrated multi-technology processes, and greener, low-energy extraction pathways. Full article

Direct Contact Membrane Distillation–Crystallization (DCMD-Cr) is a synergistic technology for zero liquid discharge (ZLD) and resource recovery from high-salinity brines. In this study, DCMD-Cr was integrated to desalinate real oilfield-produced water (PW) with an initial salinity of 156,700 mg/L. The PW was concentrated to its saturation point of 28 wt.% via DCMD, and the integrated crystallization increased the overall water recovery from 42.0% to 98.9%, with a decline in water flux and salt rejection, mainly due to vapor pressure lowering and scaling. The precipitated salts in the crystallization unit were recovered and identified using different techniques. The results indicated that 91% of the crystals are sodium chloride, and less than 5% are calcium sulfate. A techno-economic analysis (TEA) was performed to evaluate the economic feasibility of the integrated DCMD-Cr process with a 500,000 gallons per day (GDP) capacity. The results showed that the crystallization operating cost was dominant at USD 0.50 per barrel, while the capital cost was only USD 0.04 per barrel. The economic viability can be enhanced by recovering value-added byproducts and using renewable or waste heat, which can reduce the total cost to USD 0.50 per barrel. Full article

Lithium (Li) ion sieve is considered to have great potential in the selective extraction of Li⁺ from complex Li⁺-containing brine owing to its cost-effectiveness, excellent adsorption performance, and environmental friendliness. Nevertheless, the defects of complex regulation and control of technological parameters in the preparation process of Li ion sieve and poor recycling efficiency limit its application. In this study, spinel-type H₄Ti₅O₁₂ ion sieves (HTO) were successfully prepared through a high-temperature solid-state method for recovering Li⁺ from aqueous resources. Through the experiment of optimizing the key preparation process parameters of HTO, it was found that the optimum preparation conditions were as follows: lithium ion source of CH₃COOLi‧H₂O, calcination temperature of 800 °C, and acid (HCl) washing concentration of 0.3 mol/L. The uptake of Li⁺ by HTO aligned with the pseudo-second-order kinetic model, which was a chemical adsorption process controlled by reversible Li–H ion exchange reaction. HTO exhibited extremely high regeneration cycle characteristics, and after five cycles, it retained 96.06% of its initial adsorption capacity. The present work highlighted that spinel-type HTO has high industrial application potential in the field of Li⁺ recovery from oilfield brine. Full article

The distribution of fresh and salty groundwater is a critical factor affecting the coastal wetlands. However, the dynamics of groundwater flow and salinity in river deltas remain unclear due to complex hydrological settings and impacts of human activities. The uniqueness of the Yellow River Delta (YRD) lies in its relatively short formation time, the frequent salinization and freshening alternation associated with changes in the course of the Yellow River, and the extensive impacts of oil production and underground brine extraction. This study employed a detailed hydrogeological modeling approach to investigate groundwater flow and the impacts of oil field brine leakage in the YRD. To characterize the heterogeneity of the aquifer, a sediment texture model was constructed based on a geotechnical borehole database for the top 30 m of the YRD. A detailed variable-density groundwater model was then constructed to simulate the salinity distribution in the predevelopment period and disturbance by brine extraction in the past decades. Probabilistic particle tracking simulation was implemented to assess the alterations in groundwater flow resulting from brine resource development and evaluate the potential risk of salinity contamination from oil well fields. Simulations show that the limited extraction of brine groundwater has significantly altered the hydraulic gradient and groundwater flow pattern accounting for the less permeable sediments in the delta. The vertical gradient increased by brine pumping has mitigated the salinization process of the shallow groundwater which supports the coastal wetlands. The low groundwater velocity and long travel time suggest that the peak salinity concentration would be greatly reduced, reaching the deep aquifers accounting for dispersion and dilution. Further detailed investigation of the complex groundwater salinization process in the YRD is necessary, as well as its association with alternations in the hydraulic gradient by brine extraction and water injection/production in the oilfield. Full article

Water injection is widely recognized as one of the most important operational approaches for enhanced oil recovery in oilfields. However, this process faces significant challenges due to the formation of sulfate and carbonate mineral scales caused by high salinity in both injected water and formation water. To address this issue, the use of mineral scale inhibitors has emerged as a valuable solution. In this study, we evaluated the performance of seven machine learning algorithms (Gradient Boosting Machine; k-Nearest Neighbors; Decision Tree; Random Forest; Linear Regression; Neural Network; and Gaussian Process Regression) to predict inhibitor efficiency. The models were trained on a comprehensive dataset of 661 samples (432 for training; 229 for testing) with 66 features including temperature; concentrations of various ions (sodium; calcium, magnesium; barium; strontium; chloride; sulfate; bicarbonate; carbonate, etc.), and inhibitor dosage levels (DTPMP, PPCA, PBTC, EDTMP, BTCA, etc.). The results showed that GPR achieved the highest prediction accuracy with R² = 0.9608, followed by Neural Network (R² = 0.9230) and Random Forest (R² = 0.8822). These findings demonstrate the potential of machine learning approaches for optimizing scale inhibitor performance in oilfield operations Full article

Worldwide energy needs are growing, requiring new extraction techniques for crude oil from old reservoirs. However, conventional chemicals face difficulties when exposed to harsh reservoir environments such as solubility in high saline water and heat stability under harsh reservoir environments. This study investigates the potential of newly synthesized polymeric ionic liquids (PILs) as alternative options. A series of PILs was synthesized and characterized by using NMR and FTIR techniques. It was noticed that a PIL without ethoxy groups exhibits precipitation and therefore is not suitable for oilfield applications. However, the incorporation of ethoxy groups in the chemical structure of PILs leads to excellent solubility in low to high salinity brine. The solubility of the synthesized PILs in formation water, seawater, and deionized water, as well as their thermal stability using thermal gravimetric analysis (TGA), was assessed. In addition, the surface properties, including critical micelle concentration (cmc), surface tension (γ_cmc), surface excess concentration (Γ_max), minimal surface area per molecule (A_min), free adsorption energy (ΔG°_ads), and free micellization energy (ΔG°_mic), were also evaluated. The findings revealed that adding ethoxy groups in PILs led to a drop in Γ_max and an increase in A_min, suggesting reduced monolayer compactness at the air/water interface. The synthesized PILs demonstrated remarkable solubility, heat stability, and resistance to salt, rendering them well-suited for oilfield applications under challenging reservoir environments. Full article

Direct lithium extraction from unconventional resources requires the development of effective adsorbents. Crown ether-containing materials have been reported as promising structures in terms of lithium selectivity, but data on adsorption in real, highly saline brines are scarce. Crown ether-grafted graphene oxides were synthesized using 2-hydroxymethyl-12-crown-4, hydroxy-dibenzo-14-crown-4 and epichlorohydrin as a source of anchoring groups. The obtained carbonaceous materials were used to prepare chitosan–polyvinyl alcohol composites. The prepared materials (and intermediate products) were characterized using FTIR, XRD, Raman spectroscopy and SEM-EDS methods. Adsorption tests were performed in a pure diluted LiCl solution ([Li] = 200 mg/kg) as well as in a real, highly saline oilfield brine ([Li] ≈ 220 mg/kg), and the distribution coefficients (K_d) were determined. The obtained results show that K_d in pure LiCl solution was in the range of 0.9–75.6, while in brine it was in the range of 0.2–2.3. The study indicates that the high affinity for lithium in pure LiCl solution is mostly associated with the non-selective interaction of lithium ions with the graphene oxide matrix (COOH groups). It was also shown that the application of dibenzo-14-crown-4 moiety to graphene oxide modification groups increases the affinity of the composite material for lithium ions compared to an analogous material containing 12-crown-4-ether groups. Full article

A comprehensive hydrogeological, geophysical, and hydrochemical investigation was conducted in southeastern Hitchcock County, Nebraska, within the Driftwood Creek alluvial aquifer. This study assessed groundwater contamination stemming from the surface disposal of saline wastes from oilfield activities. A contaminated area, initially identified through regional groundwater sampling, was examined in detail. Monitoring wells were installed, and groundwater and soil samples were collected for chemical analysis. Surface electrical resistivity surveys were also performed to delineate contamination patterns. The findings revealed that the groundwater contamination originated from the leaching of residual evaporative salts through the vadose zone, beneath an abandoned emergency-evaporation brine storage pit. Data from down-hole specific conductance logs, water quality analyses, and computer-generated interpretations of surface electrical resistivity indicated that contaminant migration was primarily influenced by gravity, bedrock topography, and the local hydraulic gradient. An initial surface electrical resistivity profile survey was conducted to optimize the placement of monitoring wells and soil sampling sites within the vadose zone. Following well installation, a contaminant source with complex brine contamination patterns was detected within the shallow aquifer. Vertical electrical soundings were then carried out as the final investigative step. The data from these soundings, combined with test hole records, water level measurements, brine contaminant distribution, and soil analyses, were refined through a computer program employing the method of steepest descent. By incorporating known layer thicknesses and resistivities as constraints, this approach minimized the common issue of non-unique electrical sounding interpretations, providing information on the distribution of brine contaminants within the alluvial aquifer. Full article