Produced Water Samples Research Articles

Growth of Picochlorum celeri in produced water from the Permian Basin (US)

Produced water generated from hydraulic fracking is a waste stream that, on one hand, demands remediation, and, on the other hand, can be used as a water source to support a circular economy. In this study, we aimed to assess the ability of Picochlorum celeri to grow in two different sources of raw, untreated produced water collected in New Mexico, USA. The produced water had initial salinities of 110 and 140 PPT. Picochlorum was screened, with additional algae, on two different sources of produced water supplemented with nitrogen and phosphorus. The strain was able to grow on 25 % and 50 % produced water and achieve biomass densities between ~40 and 100 % of those demonstrated by control cultures. To separate the effects of high salinity stress from toxicity of the produced water samples, we conducted a bioassay with produced water under isotonic conditions of 60 PPT. When controlling for salinity, the contaminants associated with the two sources of produced water did not affect growth of the algae. This study provides justification to consider P. celeri as a candidate for remediation of and biomass production on produced water. Foundational studies are necessary to assess remediation potential and characterize the growth, biomass accumulation, and biomass composition of P. celeri grown on a variety of produced water streams.

Permeability shifts in chalk core during produced water reinjection

Chalk reservoirs, due to their high porosity and very low permeability, represent one of the most interesting cases for engineering studies of carbonates. They exhibit complex fluid-rock interactions because of their reactive surfaces and dense porous medium. The reinjection of produced water is an attractive strategy for managing wastewater flow from oil wells. However, the complex composition of produced water, the reactive nature of carbonate rocks, and their low permeability create challenges related to permeability loss.This study examines the stages of permeability change during core flooding experiments up to the point of complete clogging. A distinctive feature of this study is the presence of residual oil in the core samples, which simulates real reservoir conditions during produced water reinjection. The presence of residual oil is an additional factor influencing the change in core permeability, but there is no clear consensus in the research community on its impact on permeability during produced water injection.All experiments were conducted in a core flooding system simulating well conditions in terms of pressure (170 bar) and temperature (70 °C). Produced water samples from the Dan field were used to replicate the chemical and thermodynamic processes occurring in a real well. The experiments identified three stages of permeability change: an initial increase in permeability (+12%), a period of pressure stabilization, and a subsequent decrease in permeability (−8%) due to the formation of inorganic precipitates within the core channels.The primary objective of the experiments is to investigate the relationship between permeability changes and the stages of reinjection, with a focus on the effects of residual oil. The study focuses on identifying the processes occurring up to the point of complete clogging, considering the impact of residual oil saturation in the chalk core samples. Image analysis using scanning electron microscopy, particle size measurement with a zeta-potential meter, and thermodynamic scale formation modeling with ScaleCERE software were employed to explain these processes.Three stages of permeability change were identified during the injection of 200 pore volumes of produced water: increased permeability (+12%), pressure stabilization, and decreased permeability (−8%). The positive influence of residual oil saturation on the filtration and storage properties of the reservoir was established, due to the mobilization of chalk core particles. Additionally, the theory of core channel clogging during the reinjection of formation water by the formation of inorganic precipitates within the channels was confirmed.Understanding the causes of permeability reduction that occurred during the stage of permeability decrease enables the development of water purification methods specifically targeted at the causes of rock clogging. Predicting the process of injecting a mixture of produced and seawater will help in interpreting the data during disposal operations by injecting formation water into an injection well, and it will allow for the selection of effective measures to mitigate the impact on the reservoir.

Effect of Contact Time on the Sorption of Metal Ions Associated with Produced Water on Pulverized Oyster Shell (OS) as Adsorbent

The aim of this research is to investigate Metal ion sorption potentials of pulverized Oyster Shell as adsorbent in produced water from selected flow stations in the Niger Delta region of Nigeria. Produced water samples were collected from six (6) different oil drilling installations (CC7T, CC8T, WELL 2 GSS, WELL 8 TEB, AZUZUAMA ST 1, AZUZUAMA ST 2) around the Niger Delta area of Nigeria. The waste oyster shell was collected in Akpan-Andem Market in Uyo, Akwa-Ibom State and processed using well established protocols. Atomic Absorption Spectrometer (AAS) was used to determine selected metals’ Nickel (Ni), Cobalt (Co), Copper (Cu), Iron (Fe), Lead (Pb), Calcium (Ca) and Potassium (K) concentrations. The obtained values for Nickel ranged from 0.076mg/l at AZUZU-AMA ST1 flow station to 2.882 mg/l at WELL2-GSS flow station with average value of 0.745 mg/l. The obtained value for Cobalt ranged from ˂0.001 mg/l at CC-8T and CC-7T to 0.277 mg/l at AZUZUAMA ST1. Values obtained for Cu, Fe, Pb, Ca, and K ranged between: 0.195 mg/l at WELL2-GSS to 0.449 mg/l at AZUZU-AMA ST1; 2.785 mg/l to 89.279mg/l; ˂0.001 mg/l to 0.483 mg/l; 16.217 mg/l to 92.714 mg/l and 96.386 mg/l to 105.416 mg/l respectively. Generally, the amount of metal ions absorbed/adsorbed onto pulverized Oyster shell (OS) increased swiftly within 2 hours and slowly with further increase of contact time and then tended to be stable. For pulverized Oyster shell adsorbent, the adsorption/absorption capacity decreases with the increasing contact time. The adsorbent (OS) isn’t good material for removal of Calcium and Cobalt in produced water but was very effective adsorbent for Ni, Fe, and Pb removal in produced water and less effective for Cu and K removal from produced water. The study underscores the need to further probe outcome of above research at different pH and other relevant variables as well as compares its efficiency with other detoxification technologies like Detoxification by chemical reaction (DCR) technology.

Quantification and ecotoxicological contribution of volatile compounds in produced water effluents

Produced water (PW) is a significant byproduct of offshore oil and gas production, constituting a major waste stream in the North Sea. Existing regulations address only the dispersed aliphatic hydrocarbon content in PW, and limited attention is given to other potentially hazardous compounds, including benzene, toluene, ethyl benzene and xylene (BTEX), polycyclic aromatic hydrocarbons (PAHs), phenols, water-soluble petroleum constituents as well as production-related chemicals. In this study, Danish oil production PW samples were subjected to purge and trap extraction on granular activated carbon for volatile compounds identification and quantification by GC-MS analysis. The obtained analytical data correlate with toxicity assessments conducted on three trophic levels, bacteria (Aliivibrio fischeri), algae (Skeletonema costatum) and copepods (Acartia tonsa) on the whole effluent as well as on treated samples. The removal of the PW volatile fraction by purging experiments resulted in a decrease in toxicity response from 37% ± 23–65% ± 16 across the tested species. The chemicals identified in this study and their toxicity response enhance the comprehension of the PW effluent composition and inform the development of strategies for offshore reservoir wastewater.

Produced water geochemistry from hydraulically stimulated Niobrara Formation petroleum wells: Origin of salinity and temporal perspectives on treatment and reuse

Produced water (i.e., a mixture of returned injection fluids and geologic formation brines) represents the largest volumetric waste stream associated with petroleum production in the United States. As such, produced water has been the focus of intense study with emphasis on understanding the geologic origin of the fluids, environmental impacts of unintended or intentional release, disposal concerns, and their commodity (e.g., lithium) potential. However, produced water geochemistry from many active petroleum plays remain poorly understood leading to knowledge gaps associated with the origin of brine salinity and parameters (e.g., radium levels) that can impact treatment, disposal, and possible reuse. Here we evaluate the major ion geochemistry, radium concentrations, and stable water isotope composition of ~120 produced water samples collected from 17 producing unconventional petroleum wells in Weld County, Colorado from the Late Cretaceous Niobrara Formation. This sample set encompasses eight produced water time series from four new wells across production days 0 to ~365 and from four established wells across production days ~1000 to ~1700. Additionally, produced water from nine other established Niobrara Formation wells were sampled at discrete time points ranging from day 458 to day 2256, as well as hydraulic fracturing input fluids. These results expand the available Niobrara Formation produced water geochemical data, previously limited to a few wells sampled within the first year of production, allowing for the heterogeneity of major ions and radium to be evaluated. Specific highlights include: (i) observations that boron and bromide concentrations are higher in produced waters from new wells compared to older, established wells, suggesting the role of input fluids contributing to fluid geochemistry; and (ii) barium and radium concentrations vary between the producing benches of the Niobrara Formation with implications for treating radiological hazards in produced waters from this formation. Furthermore, we explore the geochemical relationships between major ion ratios and stable water isotope composition to understand the origin of salinity in Niobrara Formation brines from the Denver-Julesburg Basin. These findings are discussed with perspective toward potential treatment and reuse of Niobrara produced water prior to disposal.

Geochemical fingerprinting and statistical variation of 35 elements in produced water and rock material from offshore chalk reservoirs

Trace metals and metalloids occur in small quantities in the subsurface water generated from oil wells, called produced water (PW). While these substances are present in low concentrations, PW volumes are sufficiently large that they are still a potential environmental concern. This study has focused on quantifying 71 trace metals and metalloids present in PW from Danish offshore oil production sites. These metals are often a challenge to measure and are globally underreported. By employing optimized sample treatment combined with ICP-OES and ICP-SFMS methods, the full elemental screening of PW samples collected from various offshore platforms has been carried out with high accuracy. Distinct geochemical signatures involving 35 elements have been discovered and they are associated with significant site-specific variations in the concentrations of key trace metals, including W, Ba, Mo, Cu, and Tl. Utilizing Principal Component Analysis (PCA), the study has effectively distinguished between PW samples from different fields, highlighting the relevance of certain trace metals and elemental ratios as potential geochemical markers. Geochemical analysis of the chalk rock material from the same production wells as the fluid samples has shown a correlation of key elements Tl, W, Cu, Mo, Ba, and As in the chalk with the produced water, potentially indicating the origin of the metals. The study has revealed a high compositional variability of PW and found that elements including Zn, Co, Hg, and Cs occur in concentrations of magnitude higher than previous estimates from reports. In addition, there is high variability in concentrations at different sampling times, underlining the need for environmental monitoring and developing more informed management strategies for the main offshore PW stream. The variability in concentrations in space and time leads to large uncertainties in environmental reporting based on a few samples. The detailed sampling campaign reported here for the first time highlights the need for much more frequent sampling, ideally continuous monitoring. The safety of produced water discharge to sea can be significantly underestimated by limited sampling. This paper provides the first field-specific and time varied screening of heavy metals in real produced water and shows the discrepancy in our understanding of the environmental impact of PW.

Mitigation of biocorrosion of X80 carbon steel by a shale microbiome biofilm using a green biocide enhanced by d-amino acids

Microbiologically influenced corrosion (MIC) in shale gas field is a major threat with the hydraulic fracturing fluid injected into the subsurface. In this study, the microbiome collected from a shale gas produced water sample was extracted and cultivated in ATCC 1249 medium modified with 10 g/L NaCl anaerobically at 30 °C. d-amino acids, which were reported as biocide enhancers, were found to enhance 2,2-dibromo-3-nitrilopropionamide (DBNPA) biocide on the mitigation of shale microbiome MIC on X80 carbon steel. The combination of 50 ppm (w/w) d-leucine + 50 ppm d-alanine + 1 ppm d-tyrosine had the best enhancement effect on 50 ppm DBNPA with 84 % less weight loss, and 67 % lower corrosion current density (icorr) compared to 50 ppm DBNPA alone. The corrosion data were consistent with the enhanced biofilm inhibition observation. The experimental data also indicated that d-tyrosine used alone at a low dosage of 1 ppm enhanced DBNPA considerably, with 44 % less weight loss and 47 % less icorr. The electrochemical results showed the positive response of shale gas microbiome biofilm to the injected magnetite nanoparticles indicating the extracellular electron transfer might be a main mechanism for its corrosion.

Assessment of produced water from oil and gas field Gujar Khan, Punjab, Pakistan

This study was conducted to analyze the physiochemical and heavy metal concentrations in produced water of Missa Kaswal Oil field Gujar khan, Punjab, Pakistan. Produced water samples were collected from various locations points and analyzed for various parameters by using standard operation procedures. According to Pakistan Environmental Protection Agency, pH, temperature was noted with in permissible limit, total dissolved solids, chlorides, fluorides and oil and grease concentrations were found very high. The concentration of chloride and oil and grease were found several times higher as compared to Pak-EPA. Heavy metals results of the research samples are compared with Pakistan Environmental Protection Agency. From the results it was found that nickel (Ni), lead (Pb), manganese (Mn), zinc (Zn) and arsenic (As0 were within the permissible limits while chromium (Cr) concentration was observed in produced water above the permissible limits. So overall study concluded that wastewater which is released from oil and gas sector is highly polluted. So, it is strongly recommended that Pakistan Environmental Protection Agency should regular check and monitor that wastewater before releasing into the environment.

Characterization and Quantification of Naphthenic Acids in Produced Water by Orbitrap MS and a Multivariate Approach.

Naphthenic acids (NAs) naturally occur in crude oil and its associated produced water, presenting significant challenges, such as corrosion, in refinery apparatus and ecotoxicity in aquatic habitats. This study delineates a multivariate method to quantify NAs in produced water via electrospray ionization coupled with high-resolution Orbitrap mass spectrometry (ESI-Orbitrap MS). By employing liquid-liquid extraction, followed by direct infusion ESI(-)-Orbitrap MS, we characterized and quantified NAs employing a partial least-squares regression (PLS) model enhanced by the ordered predictor selection (OPS) algorithm. Thirty-six produced water samples were utilized, with 24 allocated for calibration and 12 designated for validation. The PLS-OPS model demonstrated notable accuracy in predicting NA concentrations in simulated and actual produced water samples ranging from ∼30 to 300 mg·L-1. This methodology offers a rapid yet robust alternative for quantifying NAs using mass spectrometry augmented by PLS and the OPS. Its significance is underscored by its potential to equip the petroleum industry with a swift and reliable monitoring mechanism for NAs in produced water, thereby aiding in mitigating environmental and operational risks.

Dual COF functionalized magnetic MXene composite for enhancing magnetic solid phase extraction of thiophene compounds from oilfield produced waters prior to GC-MS/MS analysis

In this study, a novel COFTABT@COFTATp modified magnetic MXene composite (CoFe2O4 @Ti3C2 @COFTABT@COFTATp) was synthesized by Schiff base reaction and irre-versible enol-keto tautomerization, and employed to establish a sensitive monitoring method for six thiophene compounds in oilfield produced water samples based on magnetic solid-phase extraction (MSPE) prior to gas chromatography coupled with a triple quadruple mass spectrometer (GC-MS/MS). The designed magnetic materials exhibited unexpected enrichment ability to target thiophene compounds and achieved good extraction efficiencies ranging from 83 % to 98 %. The developed MSPE/GC-MS/MS method exhibited good linearity in the range of 0.001–100 μg L−1, and obtained lower limits of detection ranging from 0.39 to 1.9 ng L−1. The spiked recoveries of thiophene compounds obtained in three oilfield produced water samples were over the range of 96.26 %−99.54 % with relative standard deviations (RSDs) less than 3.7 %. Notably, benzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene were detected in three oilfield-produced water samples. Furthermore, the material still kept favorable stability after six recycling experiments. The adsorption kinetics, adsorption isotherms as well as adsorption thermodynamics of thiophene compounds were investigated in detail to provide insight into the mechanisms. Overall, the present work contributed a promising strategy for designing and synthesizing new functionalized materials for the enrichment and detection of typical pollutants in the environment.

A novel approach to produced water management using surfactants for water-wise energy production

Evaporation can become a prominent solution for management of the large volumes of contaminated water produced each year in the energy industry. However, improvements to the evaporation rates are needed which can be accomplished through the use of surfactants. In this paper, organic and inorganic compounds commonly found in produced water were studied in a controlled, laboratory oven to understand their effect on water evaporation rate. Organic compounds were classified in three ways: as either miscible or immiscible, as having a density less than or greater than water for immiscible compounds, and by their volatility. For each sample, the evaporation rate and surface tension were measured, and correlations were made between the two. As the cationic charges of salts added to water increased from +1 to +3, the evaporation rates decreased and the surface tension increased. Monovalent cationic charges were 60% higher than solutions containing divalent or trivalent cations. From the organic compounds tested, the addition of surfactants to deionized water increased evaporation rates by more than 50% while the addition of immiscible organic compounds hindered these rates. Surfactants reduced the surface tension of these samples thus positively affecting the evaporation rates. Applying surfactants to basic salt solutions showed evaporation rates increased with the greatest being that of sodium chloride, the most common salt in produced water. Increases in salt concentrations lowered evaporation rates and increased surface tension while increases in surfactant concentrations did not necessarily continue to reduce surface tension and increase evaporation rates. When surfactants were added to produced water samples, up to a 27% increase in the rates of evaporation were observed. The quality of produced water varies from region to region and therefore some surfactants may have a greater effect in one type of water than another.

Assessment of raw and produced water quality at Al-Doura water treatment plant

Abstract The population growth rate has increased rapidly in recent years so there is an obligation to evaluate the productivity of produced water (PW) by investigating the operation of the Water treatment plant (WTP). WTP’s primary goal is to remove and destroy harmful organisms from contaminated water to make it safe for human consumption. The quality of PW depends on the performance of WTP. This study aims to assess the removal efficiency of Al-Doura WTP in Baghdad City/Iraq and ensure that the drinking water quality meets the drinking water standards. Twenty-two water quality parameters are analysed over four years (from January 2020 to December 2023). The samples of raw water are collected from the Tigris River at the intake of the WTP, while the PW samples are collected at the final stage where the water undergoes treatment before being distributed to the consumers through the network. The measured parameters are Temperature, Turbidity, Alkalinity as CaCO3, Total Hardness as CaCO3, Calcium as Ca, Chloride as Cl, Magnesium as Mg, pH, Colour, Electrical Conductivity EC, Free chlorine (Residual chlorine), Sulphate as SO4, Total dissolved solids, Suspended solids, Iron as Fe, Fluoride as F, Aluminium as AL, Nitrite as NO2, Nitrate as NO3, Ammonia as NH3, Silica as Sio2, and Orthophosphate as PO4. In this study, special focus is concerned with some of these water quality parameters, temperature, pH, electrical conductivity EC, and Turbidity. The analysis is sub-categorized into winter and summer seasons. The SPSS software is used to analyse the data. The results indicate that there is no significant difference between the temperature of raw water and that of the produced water, and the pH values indicate slight alkalinity for raw water in both seasons. Electrical conductivity Ec values for both raw and produced water are found always greater in winter than in summer. The turbidity is found to satisfy the permissible limits for both the Iraqi and World Health Organisation standards (Turbidity < 5 NTU). The drinking water produced from the Al-Doura water treatment plant is found to be within Iraqi and WHO standards, The high difference in turbidity concentration before and after treatment and the removal efficiency excellent value of close to 98% indicates that the plant is highly effective and reflects the effective process of Al-Doura WTP in removing particulate matter and improving water clarity. The Pearson, correlation analysis results indicate a strong (positive, and negative) correlation in the relationship among some parameters reported in this article.

Direct lithium extraction from Canadian oil and gas produced water using functional ionic liquids – A preliminary study

In this study, a functional ionic liquid system was successfully applied to extract lithium from the Canadian oil and gas produced water samples without further dilution at ambient conditions. The effects of interference cations, dissolved organics and other factors on the extraction were studied in detail. Chemical precipitation method was applied to reduce the concentrations of divalent ions before the ionic liquid extraction. The extraction efficiency is about 70% on average and can be as high as 90%. It appears that this extraction method can be directly applied to the oilfield brine samples with both high Na/Li and Mg/Li ratios. In addition, it seems that the dissolved organics in the produced water did not impact the extraction efficiency. Efforts shall be made in the future to reduce the cost by replacing the diluent with another type of solvent and further improving the recycle and reuse of the IL systems. In summary, the technology can achieve satisfactory lithium extraction from the Canadian oil and gas produced water.

Offshore produced water treatment by a biofilm reactor on the seabed: The effect of temperature and matrix characteristics

In many industrial processes a large amount of water with high salinity is co-produced whose treatment poses considerable challenges to the available technologies. The produced water (PW) from offshore operations is currently being discharged to sea without treatment for dissolved pollutants due to space limitations. A biofilter on the seabed adjacent to a production platform would negate all size restrictions, thus reducing the environmental impact of oil and gas production offshore. The moving bed biofilm reactor (MBBR) was investigated for PW treatment from different oilfields in the North Sea at 10 °C and 40 °C, corresponding to the sea and PW temperature, respectively. The six PW samples in study were characterized by high salinity and chemical oxygen demand with ecotoxic effects on marine algae S. pseudocostatum (0.4%<EC50<2.7%). In continuous operation over a year, MBBR achieved a stable COD removal of 64 ± 5% at 10 °C and 68 ± 8% at 40 °C. Batch experiments revealed that most dissolved compounds were removed (up to 63%) within 3 h of treatment. High temperature (40 °C) was a key parameter to achieve a faster kinetics with degradation constant rate (k) up to eight-fold faster compared to 10 °C. Alongside contaminants removal, PW toxicity was also reduced (64–89%) during MBBR at both temperatures, hot and cold. The toxicity reduction was most likely related to the elimination of dissolved organic compounds, such as phenols, naphthalenes and BTEX. The biofilm was able to handle PW with high oil in water content from unstable production, as well as high salinity. Thus, MBBR seems to be a realistic solution to treat PW with complex and variable composition by removing harmful components towards the zero harmful discharge goal.

Treatment of Produced Water from Niger Delta Oil Fields Using Selected Bio-Adsorbents

Produced water (PW) is the vast amount of water produced from subsurface during the extraction of oil and gas. PW contains heavy metals which are detrimental to the environment. The majority of PW treatment technologies, which have been in use for many years, have reportedly failed to bring some impurity and metal concentrations down to permissible disposal levels. This study was done to determine how well three locally available materials which are eggshells, groundnut shells, and sugarcane bagasse used in the treatment of PW obtained from Niger Delta oil fields. The adsorbents were ground, and sieved into sizes of 425 and 1180 microns. They were treated individually with diluted nitric acid (400mL of 0.4mol/ LHNO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;) for 24 hours to remove pigments. They were filtered, dried, and rinsed with distilled water until the pH became neutral. PW samples were analysed for heavy metals using an Atomic Absorption Spectrophotometer (AAS). The PW samples were treated with the bio-adsorbents in a batch technique. The metals analysed were As, Cu, Pb and Fe. The bioadsorbents were able to reduce the concentration of the metals to 87%, 91%, 100% and 88% respectively. Langmuir and Freundlich isotherm models were used to analyse the adsorption system. It was observed that the finer the adsorbents the better the adsorption result. 425 microns was able to produce a better result compared with 1180 microns.

Exploring Innovative Applications of Evaporative Cooling for High-Total-Dissolved-Solids Produced-Water Treatment

Summary This research delves into the pioneering application of evaporative cooling (EC) to address the challenge of reducing total dissolved solids (TDS) in produced water generated during hydraulic fracturing operations in the Permian Basin. In this study, we used a meticulously designed laboratory-scale EC system comprising three cooling pads, a fan, a water reservoir, and a pump. Through a systematic series of experiments, both synthetic and authentic produced-water samples were treated, shedding light on the potential of this novel approach. The EC system efficiently processed untreated produced water, circulating it through the cooling pads, all while closely monitoring crucial variables such as inlet and outlet temperatures, relative humidity, and remaining water volume, utilizing a state-of-the-art temperature and humidity meter. Control experiments were systematically conducted to probe the influence of varying salinities, achieved by introducing NaCl into distilled water, encompassing a wide range from 0 ppm to 70,000 ppm. In addition, we extended our evaluation to real produced-water samples collected from diverse regions within the Permian Basin (Delaware, Northern Midland, and Southern Midland), reflecting the system’s capability to manage high salinity and the diverse impurities inherent to oil and gas production. A comparative analysis of energy consumption was undertaken, positioning EC against conventional thermal evaporation techniques. The findings revealed a compelling insight that differences in EC efficiency between synthetic and real oilfield brines were primarily attributed to the presence of sodium (Na+) and chlorine (Cl-) contents rather than the overall TDS concentration. Across all experiments, the system consistently achieved remarkable TDS removal efficiencies, hovering around the 100% mark for both synthetic and authentic produced-water samples. Moreover, the study unveiled a significant advantage of EC, as it proved to be significantly less energy-intensive when juxtaposed with conventional thermal evaporation methods. In addition, our experiments revealed that divalent ions like CaCl2 tend to lower the treatment efficiency compared to monovalent ions, adding a crucial dimension to our understanding of EC in water treatment. The EC system demonstrated remarkable efficiency, achieving nearly 100% TDS removal in both synthetic and real samples while being significantly less energy-intensive than conventional thermal evaporation methods. This research underscores EC’s potential as an effective, sustainable, and economical solution for high-TDS water treatment, with promising applications in industrial settings. The study also draws parallels between EC and air conditioning systems, suggesting its versatility in various industrial applications.

Identification of Interwell Interference Based on Hydrogeochemical Characteristics of Produced Water from Coalbed Methane Wells: A Case Study in the Southern Qinshui Basin, China

Summary Interwell interference is the superposition effect of coalbed methane (CBM) reservoir pressure. This study aims to provide a new direction for the quantitative analysis of interwell interference from the hydrogeochemical characteristics of produced water from CBM wells. A total of 24 produced water samples collected from the Panhe (PH) group, Shizhuangnan (SZN)-1 group, and SZN-2 group in Qinshui Basin were selected for the comparative analysis. The water type of all water samples is characterized by Na-HCO3, with Na+ being the main total dissolved solids (TDS) provider. The self-similar major ionic characteristics of the PH and SZN-2 groups are prone to the occurrence of interwell interference. The δD and δ18O show that the main source of produced water is atmospheric circulating water. The similar isotope characteristics of produced water in the PH and SZN-2 groups represent that there is remarkable interwell interference. Sr, As, Cu, Ga, Li, Rb, Sn, Mo, and V are selected as indicator elements. In the cluster analysis, all CBM wells form a single cluster in the PH and SZN-2 groups in the first three iterations, indicating interwell interference. According to the established fuzzy discriminative model, interwell interference is divided into two types—strong interwell interference and weak interwell interference. Most CBM wells in the PH and SZN-2 groups show strong interwell interference. This study can provide theoretical foundations for the dynamic pressure regulation and well pattern infilling of CBM wells.

Evaluating Source, Scale Risk, and Corrosion Risk of the Produced Water Samples from the Appalachian Basin Based on a Geochemical Database

Summary Statistically, oil and gas production can generate up to 20 times the oil equivalent of produced water. The composition of produced water samples reflects its source, its interactions with reservoir rocks, and downhole (DH) facilities, which are critical for basin evolution, water source determination, and the monitoring, management, and optimization of oil and gas production. For example, scale and corrosion, two of the most severe flow assurance issues accompanied by produced water, can lead to billions of dollars lost every year. However, few studies have developed a standard protocol to extract such valuable information from produced water compositions due to a lack of data and professional models. Using produced water geochemical data from the Appalachian Basin, one of the largest natural gas producers in the US, from the United States Geological Survey (USGS) Produced Waters Geochemical Database (PWGD), we developed a standard protocol to investigate the produced water source, evolution history, and scale and corrosion risks under both DH and surface conditions by means of incorporating the professional models for water-rock interaction and corrosion. The results show that the produced water from the Appalachian Basin possibly evolves from seawater evaporation following a typical evolution pattern of ion concentration and water isotopes, while a group of time-elapsed samples indicates that such an evolution pattern can also be due to the mixture of the injected water and reservoir water. In addition, most produced water samples show obvious risks of mineral scaling (e.g., calcite, barite, and siderite) and CO2 corrosion with corresponding mitigation strategies recommended. This study not only developed a reliable data processing and analysis protocol but also showed the valuable information a systematic analysis of produced water samples can provide for actual oil and gas production.

Removal of Heavy Metals from Produced Water Using Activated Carbon from Coconut Husk Enhanced with Graphene Oxide

Produced water, which contains a high amount of hydrocarbons, heavy metals, and other pollutants, is one of the major waste streams in the Niger Delta's oilfields and refineries. The treatment of produced water can be done in a variety of ways, including physical (desalination, membrane separation and, adsorption), chemical (precipitation, absorption and, oxidation), and biological. The heavy metals and contaminants in the wastewater pose a threat to living creatures and the environment. This research evaluates the effectiveness of Activated carbon modified with Graphene oxide, a new thriving material for researchers derived from graphite, to improve the adsorption capacity of coconut husk using the “wet impregnation technique” for the removal of heavy metals from produced water. Batch adsorption of the pollutant was studied for the Activated Carbon, and the modified activated carbon (AC-GO) at a time intervals, for each of the adsorbents. The removal efficiency of the adsorbent was found to increase proportionately from 6.71% to 92.96%, 3.01% to 52.23% and 51.28% to 67.77% for Cd, Ni and Pb respectively with increasing contact time. Atomic absorption spectroscopy (AAS) analysed the treated produced water samples. The adsorption isotherms and kinetics studies of the adsorbed metals were evaluated and correlated with empirical models.

A mechanistic mathematical model for the treatment of synthetic oil-field wastewater (produced water) by electrocoagulation process using aluminium electrodes.

Produced water (PW) is the largest by-product that comes out of the oil wells during oil and gas (O&G) field exploration. PW contains high-salt concentration along with other organic and inorganic components; therefore, PW must be treated before disposal. Electrocoagulation (EC) is an effective treatment method to remove pollutants from PW which has been the focus of many experimental studies; however, a mathematical model specifically for PW treatment by EC has not been developed yet. In this work, a comprehensive mathematical model has been developed to elucidate the role of EC operating parameters on the PW treatment performance and determine the mechanism for COD (Chemical Oxygen Demand) removal. The present model considers and identifies the dominant Al-hydroxy complex species and their contribution to the COD removal from synthetic PW samples by estimating their rate constants and comparing their magnitudes and investigates multi-scale modelling of the EC reactor. The influence of working parameters such as current density, initial pH, interelectrode distance, mixing speed and solution volume of PW on Al coagulant production and COD removal was investigated and modelled. The study estimates the rate constants of the reactions taking place for COD removal by EC process and by comparing their magnitudes identifies the dominant reactions and coagulant species involved in the process. The mathematical model prediction of COD removal fits well with the experimental data at 10mAcm-2, 15mAcm-2 and 20mAcm-2 current density with R2 value of 0.96, 0.97 and 0.92, respectively and for dissolved Al concentration R2 value of 0.96, 0.99, and 0.97, respectively. The simulated results reproduced a good fit at initial pH of 6.1, 7.3 and 8.6 with R2 value of 0.92, 0.96 and 0.98, respectively for COD removal. The mathematical model and the experimental results showed the role of dominant Al-hydroxy complex species such as , , , and in controlling the COD removal process. Under different operating conditions considered in the study, the model also predicted the COD removal performance of the EC reactors at different reactor volumes with R2 value of 0.96 for higher solution volume and larger reactor. The model presented and rate constants determined in the study will provide a theoretical basis for designing, scaling up and operating the EC reactor for oil-field PW treatment.