Oilfield Wastewater Research Articles

Perovskite/cobalt-based metal-organic framework hybrid promotes hydrogen production from oilfield wastewater electrolysis

Hydrogen has been recognized as a new green energy source. However, in regions where fresh water is scarce, research on the use of complex water systems, such as seawater and oilfield wastewater, to produce hydrogen by electrolysis instead of fresh water has become a pressing issue. In this paper, a low-cost and easy-to-synthesized hybrid catalyst composed of perovskite oxide SrCo0.7Fe0.3O3-δ (SCF) and cobalt-based metal-organic framework (Co-MOF) were synthesized using a simple and feasible in-situ coprecipitation method and exhibited excellent hydrogen evolution reaction (HER) activity in oilfield wastewater. The improvement of activity can be attributed to the synergistic effect between the two materials, which have more concentration of oxygen vacancies and more HER active sites due to Co ion migration. This work provides a practical approach to enhance HER activity in complex water systems by constructing spatial composite structures.

Electronic structure regulation of Cu-based Ruddlesden-Popper perovskites by cobalt doping for enhanced degradation of oilfield fracturing wastewater in electrocatalytic peroxymonosulfate system

Purification of oilfield fracturing wastewater is the most challenging type of oilfield wastewater treatment. In this work, a heterogeneous electrocatalytic peroxymonosulfate (PMS) system was established to treat oilfield wastewater using Co-doping induced Cu-based Ruddlesden-Popper (RP) perovskites as catalysts. Characterization results illustrated that the obtained catalysts were generated the heterojunction of LaCoO3/La2CuO4 and the Co would transfer electrons to Cu, resulting in a higher chemical oxygen demand (COD) degradation efficiency (> 80 %) of oilfield fracturing wastewater under the neutral environment. Singlet oxygen (1O2) played the main function for COD removal with analysis results of reactive oxygen species (ROS). Experimental results and theoretical calculations indicated that the reduction effect of carbon felt (GF) cathode and the redox cycle of Cu(I)/Cu(II) and Co(II)/Co(III) accelerated the activation of PMS. Moreover, the lattice oxygen participated in the generation of ROS. Significantly, the LaCoO3/La2CuO4 heterojunction displayed a higher total density of states (TDOS) value near the Fermi level, implying their favorable electron transfer for PMS activation. This study opens new avenue for resolving the challenge of oilfield fracturing wastewater pollution.

Study on pretreatment technology of Oilfield Industrial Sewage

Abstract At present, Oilfield industrial sewage treatment has not yet formed mature technology. However, with the development of tight oil blocks and the construction of large-scale fracture network fracturing, the industrial sewage generated in A oilfield (including fracturing flow-back fluid, substitution fluid, water for well-flushing, pressure relief water, etc.) has increased year by year. The quality of produced water in oilfield has gradually deteriorated. Oilfield wastewater treatment is becoming more and more difficult. The built oil-bearing wastewater treatment process has shown inadaptability. In recent years, by analyzing the process operation parameters, studying the characteristics of oily wastewater treatment process, and combining with years of practical management experience, A oilfield has optimized the industrial wastewater pretreatment process. Optimize the process flow according to the actual development and production. This study ensures the development effect of the oilfield. It lays the foundation for further reducing the investment and operation cost of sewage station renovation. At the same time, it is great significance to study and optimize the pretreatment process of industrial sewage in oil field.

Supercritical water synthesized Ni/ZrO2 catalyst and its application in the harmless treatment of oilfield wastewater in supercritical water

Supercritical water (SCW) catalytic gasification is a clean and efficient technology with prominent advantages in treating oily wastewater generated in oilfields. SCW synthesis is a promising one-step preparation method for nano-catalytic materials, while the influence of organic matter on SCW synthesis materials remains to be studied. This study focuses on the synthesis of the Ni/ZrO2 catalysts by the supercritical water synthesis (SCWS) method, particularly examining how different types and concentrations of organic matter affect the catalysts’ pore information and structural characteristics. It found that glycerol acted as a more effective precursor for generating reducing gases compared to glucose. This is attributed to glycerol’s capacity in SCW to generate reducing gases for activating a greater number of Ni site within the catalyst, and the 5 wt% glycerol should be a proper concentration for SCWS of Ni/ZrO2. When employed in SCW treatment of oilfield wastewater, the Ni/ZrO2 catalyst demonstrated impressive results, achieving the carbon gasification efficiency of 99.1 % and a chemical oxygen demand (COD) removal efficiency of 100 % at 500°C. These findings indicate that the SCW technique can effectively and harmlessly treat oilfield wastewater using the Ni/ZrO2 catalyst under relatively mild conditions, showing its potential as an innovative solution for wastewater management in the oil industry.

A Promising Device Based on Step Stage Theory for Highly Effective Treatment of Oil Field Wastewater

A Promising Device Based on Step Stage Theory for Highly Effective Treatment of Oil Field Wastewater

Effect of Light and Dark Regimes on Cultivation of Microalgae-Bacteria Consortium for Oilfield Wastewater Treatment

Effect of Light and Dark Regimes on Cultivation of Microalgae-Bacteria Consortium for Oilfield Wastewater Treatment

Superhydrophilic Self-supported Perovskite Oxides for Oxygen Evolution Reactions in Oilfield Wastewater

Superhydrophilic Self-supported Perovskite Oxides for Oxygen Evolution Reactions in Oilfield Wastewater

AgIn5S8/g-C3N4 Composite Photocatalyst Coupled with Low-Temperature Plasma-Enhanced Degradation of Hydroxypropyl-Guar-Simulated Oilfield Wastewater.

The effective treatment and recovery of fracturing wastewater has always been one of the difficult problems to be solved in oilfield wastewater treatment. Accordingly, in this paper, photocatalytic-coupled low-temperature plasma technology was used to degrade the simulated wastewater containing hydroxypropyl guar, the main component of fracturing fluid. Results indicated that hydroxypropyl-guar wastewater could be degraded to a certain extent by either photocatalytic technology or plasma technology; the chemical oxygen demand and viscosity of the treated wastewater under two single-technique optimal conditions were 781 mg·L-1, 0.79 mPa·s-1 and 1296 mg·L-1, 1.01 mPa·s-1, respectively. Furthermore, the effective coupling of AgIn5S8/gC3N4 photocatalysis and dielectric-barrier discharge-low-temperature plasma not only enhanced the degradation degree of hydroxypropyl guar but also improved its degradation efficiency. Under the optimal conditions of coupling treatment, the hydroxypropyl-guar wastewater achieved the effect of a single treatment within 6 min, and the chemical oxygen demand and viscosity of the treated wastewater reduced to below 490 mg·L-1 and 0.65 mPa·s-1, respectively. In the process of coupled treatment, the AgIn5S8/gC3N4 could directly absorb the light and strong electric field generated by the system discharge and play an important role in the photocatalytic degradation, thus effectively improving the energy utilization rate of the discharge system and enhancing the degradation efficiency of hydroxypropyl guar.

Sn-doped cobalt–iron hydroxide nanoarrays for enhanced electrocatalytic oxygen evolution in oilfield wastewater systems

Developing efficient electrocatalysts suitable for oilfield wastewater is considered the most crucial aspect of advancing photoelectrochemical water splitting for hydrogen production in arid regions. In this work, Sn-doped cobalt iron hydroxide (SnCoFe-LDH/NF) with a nanoarray structure was successfully prepared in situ on nickel foam using a simple electrodeposition method. The catalyst exhibits high oxygen evolution reaction (OER) activity in 1.0 mol L−1 KOH, requiring only an overpotential of 239 mV to provide a current density of 10 mA cm−2, with a Tafel slope as low as 37.8 mV dec−1. More importantly, it also maintains excellent electrocatalytic activity in 1.0 mol L−1 KOH+oilfield wastewater. The enhancement of electrocatalysis performance can be attributed to the incorporation of Sn ions and layered structure of hydroxide, which increases the inherent activity of the materials, speeds up the kinetics, and improves the synergy between the hydroxides. This study proposes a simple and efficient strategy to prepare cheap and efficient electrocatalysts operating in complex water systems.

Ferrate (IV) synthesis using derived persulfate during treatment of oil recovery wastewater

ABSTRACT Using oil recovery wastewater as the target material, the degradation of organic matter in oilfield wastewater was studied in an anodic oxidation system using Ti/Ru-Ir oxide-coated anode and 0.7mMNa2SO4 as the electrolyte. The TOC of the wastewater was 210 mg/L at the beginning of the electrolysis in the electrolysis system, and it decreased from 210 to 93.6 mg/L after 50 min of electrolysis. Under the action of this system, sulfate was oxidized to persulfate, and the apparent concentration of persulfate was 15.02 mM, oxidation and degradation of organic matter in wastewater by the action of newly generated persulfate.. Afterwards, NaOH and Fe2(SO4)3 were added to the electrolyzed wastewater, and the TOC in the wastewater was further reduced to 25.1 mg/L due to the coagulation effect of the newly generated Fe(OH)3 precipitate. The TOC removal rate of the wastewater treated by this process reached 88.0%, which meets the discharge requirements. At the same time, the derived persulfate oxidized Fe(OH)3 to generate a green substance, which was identified as Na2FeO3 by IR, UV, and XRD analyses. Na2FeO3 served as a highly effective water-purifying agent, demonstrating superior performance when compared to FeO4 2-. The method reported in this study not only provides a strategy for waste resource recycling but also offers the potential for mass production of ferrate (IV).

Study on the Catalytic Mechanism of MAl2O4:Cr Catalysts (M = Mg, Co, Zn) under the Synergistic Effect of Ultrasound and Simulated Solar Irradiation on the Degradation of Oil and Gas Field Wastewater

Study on the Catalytic Mechanism of MAl2O4:Cr Catalysts (M = Mg, Co, Zn) under the Synergistic Effect of Ultrasound and Simulated Solar Irradiation on the Degradation of Oil and Gas Field Wastewater

Photocatalytic activity and mechanism of YMnO3/NiO photocatalyst for the degradation of oil and gas field wastewater.

One-step hydrothermal method has been used to synthesize YMnO3@NiO (YMO@NO) photocatalysts with high photocatalytic activity for the degradation of oil and gas field wastewater under simulated solar irradiation. Through various characterization methods, it has been confirmed that the YMO@NO photocatalyst comprises only YMO and NO, without any other impurities. The microstructure characterization confirmed that the YMO@NO photocatalyst was composed of large squares and fine particles, and heterojunction was formed at the interface of YMO and NO. The optical properties confirm that the YMO@NO photocatalyst has high UV-vis optical absorption coefficient, suggesting that it has high UV-vis photocatalytic activity. Taking oil and gas field wastewater as degradation object, YMO@NO photocatalyst showed the highest photocatalytic activity (98%) when the catalyst content was 1.5g/L, the mass percentage of NO was 3%, and the irradiation time was 60min. Capture and stability experiments confirm that the YMO@NO photocatalyst is recyclable and electrons, holes, hydroxyl radicals and superoxide radicals play major roles in the photocatalysis process. Based on experiments and theoretical calculations, a reasonable photocatalytic mechanism of the YMO@NO photocatalyst is proposed.

Effect of Ba2+ on the biomineralization of Ca2+ and Mg2+ ions induced by Bacillus licheniformis.

The effect of barium ions on the biomineralization of calcium and magnesium ions is often overlooked when utilizing microbial-induced carbonate precipitation technology for removing barium, calcium, and magnesium ions from oilfield wastewater. In this study, Bacillus licheniformis was used to bio-precipitate calcium, magnesium, and barium ions. The effects of barium ions on the physiological and biochemical characteristics of bacteria, as well as the components of extracellular polymers and mineral characteristics, were also studied in systems containing coexisting barium, calcium, and magnesium ions. The results show that the increasing concentrations of barium ions decreased pH, carbonic anhydrase activity, and concentrations of bicarbonate and carbonate ions, while it increased the contents of humic acids, proteins, polysaccharides, and DNA in extracellular polymers in the systems containing all three types of ions. With increasing concentrations of barium ions, the content of magnesium within magnesium-rich calcite and the size of minerals precipitated decreased, while the full width at half maximum of magnesium-rich calcite, the content of O-C=O and N-C=O, and the diversity of protein secondary structures in the minerals increased in systems containing all three coexisting ions. Barium ions does inhibit the precipitation of calcium and magnesium ions, but the immobilized bacteria can mitigate the inhibitory effect. The precipitation ratios of calcium, magnesium, and barium ions reached 81-94%, 68-82%, and 90-97%. This research provides insights into the formation of barium-enriched carbonate minerals and offers improvements for treating oilfield wastewater.

Effective degradation of recalcitrant naphthenic acids by the Fe(III)/peroxymonosulfate oxidation enhanced by molybdenum disulfide: Degradation performance and mechanisms

In this study, molybdenum disulfide (MoS2) has been investigated as a catalyst to boost the redox cycle of Fe(III)/Fe(II) to activate peroxymonosulfate (PMS) to effectively break down cyclohexanecarboxylic acid (CHA), which is a model naphthenic acid (NA) pollutant. The optimum conditions of pH 3, MoS2 concentration of 0.4 g/L, Fe(III) concentration of 0.3 mmol/L, and PMS concentration of 2 mmol/L has been applied for complete degradation of 0.1 mmol/L CHA in 10 minutes reaction time. Based on results of electron paramagnetic resonance analysis, chemical probe and quenching experiment, it was found that all of •OH, SO4•−, 1O2, and Fe(IV) contributed to the MoS2/Fe(III)/PMS oxidation system. Eighteen CHA byproducts and three primary CHA degradation pathways were revealed according to the results of UHPLC-QTOF-MS analysis. By using XPS, SEM, and XRD to characterize the MoS2 powders before and after the reaction, MoS2 was found with high stability and the oxidation of Mo(IV) on the surface was negligible. The impacts of background anions on CHA degradation were found to be nonimportant, and commercial NAs mixture were verified to be efficiently degraded in current system. Overall results indicate the capacity and potential of MoS2/Fe(III)/PMS system to be utilized for future treatment of authentic oil and gas field wastewater.

Ordered mesoporous hairbrush-like nanocarbon assembled microfibers for solid-phase microextraction of benzene series in oilfield sewage.

The development of advanced functional nanomaterials for solid-phase microextraction (SPME) remains an imperative aspect of sample pretreatment. Herein, we introduce a novel SPME fiber consisting of graphene fibers modified with ordered mesoporous carbon nanotubes arrays (CNTAs) tailored for the determination of benzene series in oilfield wastewater, which is synthesized by an ionic liquid-assisted wet spinning process of graphene nanosheets, followed by a precisely controlled growth of metal-organic framework and subsequent pyrolysis treatment. The resulting robust microfiber structure resembles a "hairbrush" configuration, with a crumpled graphene fiber "stem" and high-order mesoporous CNTAs "hairs". This unique architecture significantly enhances the SPME capacity, as validated by gas chromatography-mass spectrometry. The hairbrush-like nanocarbon assembled microfibers possess structural characteristics, a high specific surface area, and numerous binding sites, offering efficient enrichment of benzene series compounds in oilfield wastewater, including benzene, ethylbenzene, m-xylene, p-xylene, and toluene. Our analysis demonstrates that these microfibers exhibit broad linear ranges (0.2-600μg L-1), low detection limits (0.005-0.03mg L-1), and excellent repeatability (3.2-5.5% for one fiber, 2.1-6.7% for fiber-to-fiber)for detection. When compared to commercial alternatives, these hairbrush-like nanocarbon-assembled microfibers exhibit significantly enhanced extraction efficiency for benzene series compounds.

Main Controlling Factors Affecting the Viscosity of Polymer Solution due to the Influence of Polymerized Cations in High-Salt Oilfield Wastewater

In view of the high salinity characteristics of reinjection oilfield wastewater in the Gasi Block of Qinghai Oilfield, with the polymer produced by Shandong Baomo as the research target, we systematically investigated the variations in the impact of six ions, Na+, K+, Ca2+, Mg2+, Fe2+, and Fe3+, in the produced water from polymer flooding on the viscosity and stability of the polymer solution. Additionally, we provided the primary research methods for complexation in reinjected wastewater. Experimental results indicate that the main factors leading to a decrease in polymer viscosity are high-valence cations, with the descending order of their influence being Fe2+ > Fe3+ > Mg2+ > Ca2+ > Na+ > K+. High-valent cations also effect the viscosity stability of polymer solutions, and their order from greatest to least impact is: Fe2+ > Ca2+(Mg2+) > Fe3+ > Na+(K+). This article is focused on investigating the influencing factors and extent of the impact of oilfield wastewater on the viscosity of polymer solutions. It illustrates the response mechanism of cations to the viscosity of polymer solutions in reinjection wastewater polymerization. Through this research, the goal is to provide reference control indicators and limits for the water quality of injected polymers at oilfield sites. This ensures the stability and controllability of polymers in field applications and offers theoretical guidance for polymer flooding technology.

Oil-water separation process based on microbubble air flotation membrane device and scale-up research

The treatment of oily wastewater is of great significance to oilfield production and ecological environment protection. A microbubble air flotation membrane device integrating air flotation separation and membrane separation is proposed, and a purely physical process of wastewater treatment is designed, which has significant advantages in the treatment of oily wastewater, especially in the treatment of polymer-driven oily wastewater. In this paper, we studied the oil-water separation mechanism and the removal effect of suspended solids of the microbubble air flotation membrane device, examined the handling capacity, reflux ratio, dissolved air water gas-liquid ratio on the oil removal rate, and determined the optimal parameters of the process for the handling volume of 7.8 m3/h, reflux ratio of 15.57%, dissolved air water gas-liquid ratio of 1:10. The oily wastewater is discharged from the device and filtered by special quartz sand can be achieved with the oil content and suspended solids content were below 20 mg/L, and the oil removal rate was over 95%, which reached the reinjection standard. This study can help the treatment and utilization of oilfield wastewater, and realize the water resources, energy, energy saving, and emission reduction.

Mechanism of enhanced oil recovery by nanoparticles extracted from flowback fluids of acidizing oil wells

The silicates in flowback fluids from acidizing oil wells can be used as raw materials for the synthesis of nanomaterials, that are beneficial for the treatment of produced water and enhanced oil recovery. In this paper, the nanomaterials were synthesized from acidizing flowback fluids by sol-gel method and the reaction conditions were optimized. The interfacial tension, wetting angle and surface tension of the solution were measured. The test of displacement efficiency and flooding experiments were conducted in two dimensional flat cores to reveal the mechanism of enhanced oil recovery by nanoparticles. The results indicated that the nanoparticles with a diameter of 351 nm could be extracted and synthesized from acidizing flowback solution at low pH. Compared with other nanomaterials, the synthesized nanoparticles could change the interfacial properties between oil and water due to the complex acidizing process. When the injection concentration of nanoparticles reached 300 mg/L, the decrease of water cut reached the maximum, up to 27.16%, and the recovery rate during subsequent water flooding was 32.25%. Appropriately increasing the injection concentration of nanoparticles extracted from acidizing flowback fluids was beneficial to improve the recovery rate, so that realizing the efficient development of oil and gas resources. The research results can provide a new method for the treatment of oilfield wastewater.

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.

Polyacrylamide degradation in oil field wastewater by UV/H2O2 and UV/PDS: Rapid experimental measurement and model simulation

Ultraviolet-based advanced oxidation processes (UV-AOPs) are effective for degrading refractory pollutants in wastewaters. However, performing rapid efficiency evaluations represents a significant challenge for process selection and optimization in practical application. This study investigated polyacrylamide (PAM) degradation by UV/hydrogen peroxide (H2O2) and UV/potassium peroxydisulfate (PDS) in pure water and practical oil field wastewater. Based on a previously developed mini-fluidic photoreaction system that is easy to operate and requires low sample volumes, an experimental setup for rapid evaluation of UV-AOP efficiency was constructed that enabled on-line analyses of viscosity, UV absorbance, and pH via specially fabricated flow cell devices together with off-line analyses of PAM, chemical oxygen demand (COD), and acrylamide (AM). The PAM degradation rate constants (k′PAM) in practical oil field wastewater by UV/H2O2 and UV/PDS were 2.4 and 2.1 m2 einstein−1, respectively, which were much higher than those by sole UV process (0.8 m2 einstein−1). Combing with the analyses of viscosity, UV absorbance (220 nm), pH, COD, and AM concentration, the UV/H2O2 and UV/PDS demonstrated the effectiveness in PAM degradation in oil field wastewater. Additionally, the scavenging capacities of HO• and SO4•− of practical oil field wastewater were determined, and the k′PAM values were predicted by model simulation and verified experimentally. This study provides rapid evaluation methods for UV-AOP efficiencies, which is helpful for selecting and optimizing UV-AOPs for industrial wastewater treatments.