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This paper reviews the characteristics of membrane distillation technology and the current research progress and hot issues, and compares the latest research progress of membrane distillation technology in terms of membrane material characteristics, membrane wetting and pollution, membrane material modification, research and application in oil and gas field produced water, etc. Membrane distillation technology was found to have great potential for the treatment of oilfield talent effluent, and the energy consumption limitation of membrane distillation technology can be improved by using low-grade thermal energy and coupling other processes. The improvement of membrane materials to obtain high flux and pollution resistant hydrophobic membranes is the key to achieve industrial application of membrane distillation technology. [ABSTRACT FROM AUTHOR]

Objective The study is aiming to explore the key corrosion bacteria in the production process of shale gas, and analyze the potential succession law of bacteria. Methods The 16S rRNA high-throughput sequencing analysis technology was used to sequence the bacterial flora in the fracturing fluid preparation water and produced water of a shale gas platform in Weiyuan area. Results The bacterial structure of fresh water is completely different from that of produced water and recycled flowback fluid, the richness and diversity of bacteria decreased after fracturing. The key corrosive bacteria include Arcobacter, Marinobacterium and Pseudomonas, etc. The bacterial community in the freash water is mainly composed of mesophilic, aerobic bacteria with weak functions such as sulfate reduction and acid production. While in the recycled flowback fluid, there are a large number of bacteria with functions of sulfur metabolism, acid production and biofilm production. After fracturing, in the produced water there are mainly facultative anaerobic, anaerobic or strictly anaerobic bacteria with functions such as sulfate reduction, sulfur reduction, sulfur oxidation, acid production, biofilm production, iron reduction, and some thermophilic bacteria were identified. Conclusion This provides theoretical and technical support for further research on bacterial corrosion of gathering and transportation pipelines and pipeline protection. [ABSTRACT FROM AUTHOR]

This article reviews the application o£ pervaporation technology in high salinity wastewater treatment. The effects of wastewater composition, feed water temperature, osmotic vacuum, wastewater flow state and membrane materials, are mainly discussed・ Based on the previous work, the feasibility of applying pervaporation technology to the treatment of high salinity wastewater is discussed・ The pervaporation technology is expected to become one of the important technology choices in the zero discharge of wastewater. [ABSTRACT FROM AUTHOR]

In view of the common problems of conventional water shutoff agent, such as "Either not injected or not plugged, can not deep profile control and flooding, and poor effect of increasing oil and dewatering", a novel terpolymer was prepared from acrylamide（AM）,2-acrylamide-2-methylpropanesulfonic acid（AMPS） and N-（3-dimethylaminopropyl） methacrylamide（DMAPMA）, at the same time, multiple emulsions were prepared to encapsulate the crosslinking agent. The results showed that the cross-linking time of the multi-emulsion system could be delayed more than 1 times to 5～15 d, and the optimal gel system had good temperature and salt resistance, it is suitable for reservoirs with salinity less than 100 000 mg/L and temperature between 70 ℃ and 90 ℃. The gel system has the advantages of low initial viscosity, easy injection into low permeability formation, controllable cross-linking time and high gelling strength, and the hypertonic channel is effectively blocked. [ABSTRACT FROM AUTHOR]

The produced water of oilfield binary flooding contains a large number of residual oil displacement agents such as polymers and surfactants. The interaction between oil displacement agents and water results in the enhanced stability of oil droplets and colloidal particles in the produced water. The treatment cost of traditional coagulation technology is high, the amount of sludge is large, and the quality of treated water is difficult to meet the requirements of reinjection indicators. This paper studies the influence of the process of sedimentation-aeration-biological contact oxidation-filtration on the turbidity, particle electronegativity and particle size distribution of the produced water from binary flooding. The result showed that the best process: gravity sedimentation for 12 h, aeration for 12 h under the condition of aerated water ratio of 30∶1, biological contact oxidation for 7 d, using fiber ball as filter material to filter the produced water from binary flooding. The field test has achieved good treatment effect, and the treated water quality meets the requirements of reinjection with oil content less than 5 mg/L, solid suspended solids less than 10 mg/L, and the median particle size of suspended solids less than 2 μm. [ABSTRACT FROM AUTHOR]

With the continuous increase of shale gas production in China, the associated water production is also increasing, which is the mixture of the water used for hydraulic fracturing and the brine retained in shale formation. During the treatment of produced water, valuable elements such as lithium, potassium and bromine are further enriched and concentrated. especially lithium. resources, which has broad prospects for development and utilization, and can alleviate the contradiction between supply and demand of strategic resource lithium in China. In this paper, the shale gas resources in Sichuan are introduced and summarized mainly. And the ion content in the produced water of shale gas in Weiyuan and Changning areas in southern Sichuan is listed respectively. At present, the produced water volume of each well in Weiyuan and Changning is 19 800 m³ and 15 293 m³ respectively, and the lithium content in most of the produced water is 10, 62-58, 96 mg/L, which has high economic utilization value. The reserves and prospects of lithium resources in the produced water of shale gas are predicted. The applicability of extraction method, membrane separation method and adsorption method to the extraction of lithium in shale gas produced water are summarized, which provides the reference for the comprehensive utilization of lithium resources from shale gas formation in southern Sichuan. [ABSTRACT FROM AUTHOR]

This paper summarizes the advantages and disadvantages of the existing treatment technology in oilfield oil production sewage, introduces the main components and characteristics of oilfield wastewater treatment, summarizes and summarizes the latest research achievements and existing problems of filtration technology, air flotation technology, membrane separation technology, advanced oxidation technology, biofilm technology, biological demulsification technology・ The development and innovation directions of physical, chemical and biological technologies for oilfield wastewater treatment are prospected through the problems of oilfield sewage treatment technology. [ABSTRACT FROM AUTHOR]

Chemical flooding, as the main method to improve recovery, has been widely applied in the oil- fields and has achieved good results in enhancing and stabilising crude oil recovery, but the existing chemical flooding technology are limited by reservoir geological conditions, cost effectiveness and technology level, and the recovery rate of crude oil in some oilfields is not satisfactory. The study proves that nano oil repellents can enhance crude oil production by reducing oil-water interfacial tension and changing rock wettability, are stable under complex reservoir conditions and have great potential in the field of recovery enhancement. The existence of nano-displacement agent is divided into three categories: nano-powder, nano-Pickering emulsion and nano-emulsion, and the research progress of nano-powders and nano-emulsions based on nano-SiO2, summarises the advantages and problems of nano-oil repellents, analyses the mechanism of nano-oil repellents and outlines the development trend. [ABSTRACT FROM AUTHOR]

In order to solve the pollution of oilfield fracturing flowback fluid to land and realize its resource utilization, a multi-functional sand-fixation agent of humic acid-flowback fluid was developed using organic bacterial manure, curing agent, humic acid, urea and potassium dihydrogen phosphate as raw materials by using liquid phase chemical method and homogeneous blending technology. FT-IR and SEM indicated that the multifunctional sand-fixing agent had a porous spongy structure and provided a place for the storage and release of water and nutrient elements. Under non-planting conditions, the water retention effect can reach 60 days after mixing water, sand and multi-functional sand-fixing agent. The growth experiment of leeks with multi-functional sand-fixing agent indicated that after 60 days of planting in winter, the plant height of leeks was 16cm, and the green content of leaves was 4 times that of the control group, which could meet the needs of plant growth and provide lasting water and nutrition for plants, and could be used for desert and saline land governance. [ABSTRACT FROM AUTHOR]

Sulfated scaling of oilfield injected water has a great adverse effect on production.Based on the water quality analysis results of injected water, the trend of sulphate and carbonate scaling may be deduced.The scaling samples of injected water system were analyzed by X-ray diffraction (XRD). The results show that there was incompatibility between clean water and formation water and the scale samples were mainly barium strontium sulfate scale, and mixed with a small amount of calcium carbonate scale.The factors affecting the incompatibility of injected water in oil field were discussed and the prevention scheme was put forward. [ABSTRACT FROM AUTHOR]

Shale gas is an important part of Chinas new energy strategy. The exploitation of shale gas commonly relies on hydraulic fracturing technology, with the generation of large quantities of flowback and produced water. To realize the goals of carbon peaking and carbon neutrality, it is significant to treat the flowback and produced water with high salinity and various organics cost effectively and environmentally friendly. In this review, recent progresses on biological methods (activated sludge, biofilm, membrane bioreactor, aerobic granular sludge, etc.) that used for flow back and produced water treatment are summarized, and the advantages and drawbacks of different biological methods are compared based on the characteristics of the flowback and produced water. Further, the prospects of bioaugmentation technology on flowback and produced water treatment are analyzed. This study provides an important guidance for green and efficient removal of pollutants (organic matter and ammonia nitrogen, etc.) in shale gas flowback and produced water. [ABSTRACT FROM AUTHOR]

The full text introduces the research and progress of polyacrylamide, polyacrylonitrile, polyethyleneamine, polyvinyl alcohol gel system and biopolymer gel system widely used in oilfields. Aiming at the wide application of high temperature resistant polyacrylamide gel system in high temperature reservoirs, it is divided into two major development directions of ultra-high molecular weight and chemical modification, and the application prospects of oilfield application are prospects. [ABSTRACT FROM AUTHOR]

In view of the technical problem that it is difficult to block water in high temperature and high salt fracture cave reservoir of Tahe oilfield, and the plugging agent is easy to be diluted by formation water, resulting in the decline of effective plugging section, so as to reduce the plugging effect, two types of polyacrylamide（P-71 and P-9） are selected as the main agent, sodium alginate as the auxiliary agent, sodium chloride as the viscosity reducer, hydroquinone and hexamethylenetetramine was used as crosslinking agent to prepare anti-dilution gel plugging agent （SA-PAM） with high temperature and salt tolerance, and its plugging effect was evaluated. The results showed that the optimum formula was 0.5%P-71+1%P-9+0.5% hydroquinone +0.5% hexamethylenetetramine +0.5% sodium alginate +4% sodium chloride. The plugging agent is not diluted by formation water when gelling under high temperature and high salt conditions, and the anti-dilution effect is obvious; the gel forming time at 130 ℃ was 4 h and the maximum water loss rate was 6.95% after aging for 28 d.At the same time, the proportion of bound water in the gel was relatively high, which showed that it had strong affinity for water; SA-PAM gel is aged for 30 d and passes through 5 PV formation water（2.1×105 mg/L） after scouring, the plugging rate is still greater than 85%,indicating that the gel is not easy to dehydration and instability under the conditions of high temperature and high salt, and has excellent scouring resistance. [ABSTRACT FROM AUTHOR]

Objective Aiming at the corrosion problem of carbon steel weld in the produced water environment of a gas field, trace metal elements such as Mo, Cr, Ni and Cu were added to microalloying the electrode. Method The corrosion resistances of five kinds of carbon steel weld metals with different structures were systematically evaluated by immersion corrosion method at 60 ℃ in the produced water of gas field. Result The addition of Mo and Cr elements can refine the grains and improve the corrosion resistance. Conclusions By adding 12 wt% Cr, 1.5 wt% Ni, 1.6 wt% Mo and 0.8 wt% Cr, 0.3 wt% Ni, 0.3 wt% Cu into the electrode, the electrochemical corrosion resistance of the weld structure can be improved. The corrosion products are mainly composed of FeCO3, and some samples also contain a small amount of FeS or FeS2 and CaCO3. [ABSTRACT FROM AUTHOR]

Taking a 24.9 MW ocean going ship power unit burning high sulfur oil as the object, a set of flue gas treatment system based on seawater swirl atomization was designed. Through the reconstruction and installation of the real ship, the desulfurization effect of the system was tested under the condition of burning heavy oil with sulfur content of 3.5%, the effects of liquid gas ratio, flue gas velocity, atomization pressure and inlet flue gas temperature on desulfurization characteristics were studied. The results show that the S/C of outlet flue gas, pH, PAH and turbidity of inlet and outlet washing water can meet the emission limits of the convention under the drastic change of unit load. [ABSTRACT FROM AUTHOR]

This paper summarizes the current status of industrial waste liquid treatment under the background of “carbon neutralization and carbon peaking” in sewage treatment. Hazardous waste liquid concentration treatment, oilfield coal chemical waste liquid, paint spraying waste liquid, cutting waste liquid, fine chemical waste liquid reduction and up-to-standard treatment, as well as the application status of waste acid purification, heavy metal recovery and resource utilization, and analyzed the current low temperature. The existing problems of evaporation technology are prospected for the future development of low-temperature evaporation technology. [ABSTRACT FROM AUTHOR]

In order to overcome or minimize the excessive production of undesired water amounts during the secondary and tertiary stages of oilfield development and achieve deep-water control in the dominant channels・ The basic adopts the method of physical crosslinking and gluing, and based on the analysis of the factors influencing the gelation temperature, the thermosensitive gel system with temperature stimulus response characteristics is formed, and its performance is evaluated・ The results showed that the thermal behavior of the system can be divided into three stages: polymer stretching, gel formation and structural perfection. After being heated at 90 〜120 °C for 50 d, the viscosity retention rate of the system is as high as 94・ 97% and has long-term thermal stability; it can form gel continuously in 6 xlO4 mg/L formation water and has high concentration inorganic salt tolerance; the scanning test of variable oscillation frequency showed that when the oscillation frequency changes from 0・ 01 to 1 Hz, the system shows the characteristics of strong elastomer fluid dominated by elasticity; microstructural analysis with scanning electron microscope revealed that there was interaction between polymer and nano silica. On the one hand, globular particles attached to gel dendrimers, enhanced gel strength, and on the other hand increased crosslinking density of gel network, forming pore size of 2.37 〜3・ 76 pirn and 6・ 57 〜7・ 94 |±m. [ABSTRACT FROM AUTHOR]

The produced water, generated from the exploitation of tight gas, is characterized by complex composition, high salinity, and high treatment cost. The treatment and disposal methods of the produced water were analyzed and compared. Among those methods, the dispose of high-salinity produced water by reinjection formation is generally accepted by the industry. The problems of corrosion and scaling which may occurred in the process of produced water reinjection were analyzed, and the anti.corrosion and scaling strategies of reinjection treatment in recent years were summarized. Finally, the development trend of the reinjection formation disposal of the produced water was prospected. [ABSTRACT FROM AUTHOR]

Using high-salinity oilfield water as the annulus protection liquid base fluid can easily increase the risk of corrosion and cracking of tubing and casing steel. Therefore, it is necessary to evaluate the corrosion risk of P110 S steel in the oilfield water annulus protection liquid. Firstly, the chemical components of oil field water and P110 S steel were analyzed. Then, the field conditions were simulated by using a high-temperature autoclave. The weightlessness corrosion and four-point bending experiments were carried out under the temperature of 200 ℃, CO2 partial pressure of 10 MPa and H2S partial pressure of 2 MPa, and the morphology and composition of corrosion products was analyzed by using SEM and EDS. Finally, the cross-section of the sample was analyzed. The results show that P110 S steel does not suffer from stress corrosion failure under high temperature and highacid conditions. The corrosion rate is 0.098 5 mm/a, severe pitting and local corrosion can be observed on the surface of the sample. Cross-sectional analysis shows that the thickness of corrosion product film on the sample surface is 63 μm, and the metal matrix is corroded seriously. P110 S tubing and casing steel faces a greater risk of corrosion failure under this working condition. In order to suppress the corrosion damage of the pipes, it is recommended to use fresh water or low-salinity well site water as the annulus protection liquid base fluid. [ABSTRACT FROM AUTHOR]

In view of the existing problems of many treatment processes and large mud production in the cryogenic distillation station of Yuanba Gas Field, it is planned to introduce electrochemical oxidation method for mining. The effluent is pretreated to remove ammonia nitrogen and reduce organic content. Optimized the current intensity and electrolysis time in the electrochemical oxidation reaction through a small test between. The results show that after the hardness of the produced water is removed, when the electrolysis current is 1200A and the reaction time is 30min, the ammonia nitrogen removal rate can reach 100%, while effectively reducing the organic content of wastewater. At this time, the cost of water treatment per ton is 7.56 yuan. Combined with the actual situation of the cryogenic distillation station, pilot test The process of "clarification and softening + electrolysis of ammonia nitrogen + reverse osmosis + MVR evaporation" is adopted to shorten the treatment process and effectively reduce the disposal of chemicals and sludge Cost, providing theoretical and process design support for the subsequent new resource recycling station. [ABSTRACT FROM AUTHOR]

Soil salinization is currently improved via flood irrigation and salt-washing drainage for the main crop cultivation in a typical arid desert region of Xinjiang, China. As such, most produced saline-alkali water is discharged directly through the salt-discharging channel. Loss of water resources has posed a serious threat to the local soil and ecological environment. Oleaginous microalgae offer an attractive alternative to generate biofuel in the saline-alkali land unsuitable for farming, such as desert and mudflat in recent years. However, little attention has been paid to the cultivation of oleaginous microalgae in the salt-discharging channel water with high salinity and nutrient deficiency. In this study, one species of oleaginous microalga (WY205), identified as Chlorella sp, was isolated from the salt-discharging channel water. A systematic examination was made to explore the effects of supplementation with organic carbon sources on microalgae growth and lipid accumulation. An attempt was also made to investigate the salt-tolerance, the growing and lipid producing stability of oleaginous microalga. The results showed that the addition of organic carbon sources improved significantly the growth rate and lipid yield of microalgae. Since the accumulation of microalgae lipid followed the type of growth coupling, the logistic equation and Gaden growth model were selected to describe the algal growth and kinetics of lipid generation in the salt-discharging channel water. The maximum biomass (3.03 g/L) and the highest lipid yield (1.26 g/L) were predicted at the supplementation of 2.5 g/L glucose, which were 1.35 and 2.21 times more than those treated without sugar, respectively. When the Na+ was added up to 5 g/L (equivalent to NaCl 12.72 g/L), the content of microalgae lipid reached 44.90%, while the lipid yield achieved the maximum, 21.69% higher than that of the original water from the salt-discharging channel (Na+ concentration was 2.64 g/L). Even when the Na+ concentration enhanced to 10 g/L (equivalent to NaCl 25.43 g/L), the content of microalgae lipid reached 59.71%, whereas, the lipid yield began to decline, 10.84% higher than that of the original water from the salt-discharging channel, due to the large reduction of biomass. This indicated the high salt-tolerance of oleaginous microalgae. There was no significant change in the biomass and lipid yield of alga strain after 60 days of semi-continuous culture using undiluted salt-discharging channel water for 3 cycles plus 2 times concentrated water sample for another 3 cycles (10 days for each cycle). The content of microalgae lipid maintained higher than 30% in all cycles, exhibiting good adaptability and stability. In further optimization, the culture conditions of microalgae can be extended to the growth monitoring on a large-scale in subsequent studies. The finding can provide a promising technical reference to cultivate oleaginous microalgae for resource utilization of salt-discharging channel water. [ABSTRACT FROM AUTHOR]

At present, the downhole technology of water reinjection wells in central Sichuan area can meet the requirement of produced water reinjection, but the phenomena of tube bundle break down, corrosion perforation and channeling leakage were exposed in the process of reinjection. The reinjection \veils that have been shut down due to corrosion accounted for more than 35 % of the shutdown wells. The corrosion evaluation result showed that the reinjection well casing in service in sulfur-containing block of central Sichuan was in moderate and serious corrosion, and the corrosion was intensified with the increase of temperature, showing local corrosion characteristics. Through the evaluation of corrosion inhibitor slubility and inhibition effect, the inhibitor CT2-19C was s elected and suitable for reinjection \veils in sulfur-containing blocks of central Sichuan area, the liquid-phase corrosion inhibition rate was more than 80%. [ABSTRACT FROM AUTHOR]

Aiming at the severe problems of possibilities for flammable and explosive risks during the actual production procedure, the X-ray diffractometer, ion chromatography and GC/MS were used to detect and analyze solid impurities, inorganic impurities and organic impurities in the gas well produced water initially. Then the changing law of vapor-liquid phase equilibrium of the gas well produced water system with diverse impurities under different contents was explored by laboratory experiments using the Plackett-Burman design. The results showed that the impurities in the gas well produced water mainly include solid impurities such as Fe3O4, inorganic impurities such as K+, and organic impurities such as formic acid. The impurities could affect the gas-liquid phase equilibrium of gas well produced water to different degrees. Compared with the pure methanol-water system, the impact shows a certain positive deviation overall. Moreover, FeS, MgCO3, K+, Ca2+, F-, formic acid, n-decane, n-heptane, 1, 2, 4-trimethylbenzene and ethylcyclohexane among these impurities have significant influences on the molar fraction of methanol in vapor phase, among which ethylcyclohexane has the greatest effect followed by Ca2+, and FeS is the smallest. The research results could provide a scientific and reliable theoretical basis and data source for the safe operation of gas well produced Water storage tanks, and a reference to the same types of equipment. [ABSTRACT FROM AUTHOR]

The basic properties of ternary produced water and the effect of oil displacing agent on the stability of produced water were obtained, through the analysis of the water quality, oil content-settling time relationship and oil displacing agent-oil droplet size relationship of Nan4-8 and Sanyuan-6 ASP Flooding water in Daqing Oilfield. The synergistic action between the oil displacing agents, especially the polymer, the alkali and the surfactant, has positive effect on dispersing the oil droplets, and the specific performance is as follows:the effect of alkali on the stability of ternary water has a duality. As the amount of alkali increases, the distribution of oil droplets with small particle size increases with a small part of the oil droplet size reaching the range of colloidal particle size. When the alkali amount reaches a certain value, oil droplets in the produced water will aggregate and separate. The surfactant can reduce the interfacial tension between the oil and water, promote the dispersion of the oil droplets, and at the same time, there is a repulsive force between the long-chain molecules, which can hinder the aggregation between the oil droplets. The polymer mainly increases the viscoelasticity of the produced water and oil droplet accumulation resistance, and reduces the floating speed of the oil droplets. The synergistic action of the base and the surfactant can saponify the active material in the crude oil, while the hydrolysis of the polymer itself is promoted in a certain extent, the interfacial activity is elevated, and the stability of the produced water is enhanced by the alkali at the same time. [ABSTRACT FROM AUTHOR]

The oil and gas field water analysis project is complex and has many analysis methods. It is mainly divided into traditional chemical analysis and instrumental analysis. The traditional chemical analysis includes titration method, gravimetric method and calculation method, which are cumbersome in steps and long time in period. And the titration end point is difficult to recognize because of the dark color of some water samples and many other interference factors. All these increase the error of experiment results. Instrumental analysis includes ion chromatography, spectroscopy and automatic potentiometric titration. Compared with traditional chemical analysis, the instrumental analysis method is faster and more accurate, but large-scale instruments and the gas cylinders are not easy to carry on-site tests. In order to ensure the accuracy of data measured by different methods, the advantages and disadvantages of each analysis method and the compatibility of each method are discussed in detail. The experiment result shows that chemical method is basically compatible with instrumental analysis method for formation water. The introduction of instrumental analysis refreshes the new understanding of formation water. The method of identifying formation water based on water analysis data provides a powerful geochemical basis for oil and gas exploration and development. [ABSTRACT FROM AUTHOR]

For XC gas field producing large quantities of formation water that is high salinity and difficult to treat, three dirty water treatment methods were used including the reaching standard discharge, reinjection of formation water and low temperature multi-effect distillation. Field tests have shown that the reaching standard discharge is limited for further development in the gas fields due to the high investment and processing costs; the reinjection of formation water and low temperature distillation method gradually become the focus in XC gas field water treatment mode because of its low investment, high treatment efficiency, and resource recycling. [ABSTRACT FROM AUTHOR]