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    Research Progress on Capture of CO2 by Alcohol Amine Absorption Method
    YANG Tianmeng, YANG Fan, REZEY Rehemtuli, GOU Guolei, LI Xiuhui, HOU Junwei
    Xinjiang Oil & Gas    2024, 20 (1): 52-60.   DOI: 10.12388/j.issn.1673-2677.2024.01.007
    Abstract279)      PDF (3625KB)(314)       Save

    CO2 capture,utilization,and storage are the main technologies to cope with the greenhouse climate,achieve the strategic goal of carbon peak and neutralization,lead the transformation and upgrading of the global energy system,and promote the green and sustainable development of energy. The chemical absorption methods have the characteristics of high absorption efficiency and large processing capacity,most suitable for large-scale carbon capture in various industries. Among them,the alcoho lamine method is the most widely used and the most effective. After absorbing CO2,the alcoholamine solution becomes an alcoholamine-rich solution,which can be recovered by desorption treatment for cyclic utilization. However,in the process of CO2 capture by the existing alkanolamine absorbent,there are some disadvantages such as high energy consumption and great loss of absorbent,and it is necessary to improve the alcoholamine absorber to realize high absorption efficiency and a feasible process with low regeneration energy consumption. To solve the problems of large loss of absorbent and low regeneration rate,a new mixed alcoholamine absorber was developed for improvement. For the problem of high energy consumption for regeneration,the traditional thermal desorption process is improved and microwave desorption technology is selected. This paper introduces the mechanism and characteristics of CO2 absorption by alcoho lamine method,summarizes the basis for improving the mixed alcoholamine absorber,and expounds on the principle and characteristics of CO2 capture through microwave-assisted alcoholamine,providing a reference for industrial carbon capture and environmental protection.

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    Current Status and Suggestions for Drilling Technology of CNPC Continental Shale Oil Reservoirs

    Xinjiang Oil & Gas    2024, 20 (3): 1-14.   DOI: 10.12388/j.issn.1673-2677.2024.03.001
    Abstract191)      PDF (2045KB)(79)       Save

    Shale oil with medium to high maturity is the key field for China's shale oil strategic breakthrough,and strengthening the exploration and development of continental shale oil is an important way to ensure the security of national energy supply. The technical progress of shale oil drilling in Ordos,Junggar and Songliao Basins by China National Petroleum Corporation (CNPC) was introduced in detail,including large platform factory-like well placement,horizontal well casing program optimization,"one-run drilling" in separate well sections,high-performance drilling fluids for horizontal wells,integrated geological steering and other key technologies. By benchmarking against advanced shale oil drilling technologies in North America,the gap and development trend of shale oil drilling in China were analyzed in terms of well placement and wellbore configuration,geological-engineering integration and steering technology,supporting technology for accelerating rates of penetration (ROP),drilling fluid and cementing supporting technology. Development suggestions,such as continuously promoting large platform factory-like operations,optimizing wellbore configurations,integrating ROP acceleration technologies,strengthening research on geological-engineering integration,and accelerating the research and development of new-generation steering tools,were proposed in order to achieve the goals of ROP acceleration,cost reduction,and efficiency improvement in continental shale oil drilling,and moreover,the engineering goals of the shale oil revolution.

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    Development of Viscosity Reducer for High Density Water-Based Drilling Fluid and Its Application#br#
    DENG Zhengqiang , OU Meng , BAI Hailong , JING Yujuan , HUANG Ping , SHAO Ping
    Xinjiang Oil & Gas    2023, 19 (3): 33-37.   DOI: 10.12388/j.issn.1673-2677.2023.03.005
    Abstract177)      PDF (548KB)(55)       Save

    One of the main reasons for rheology out-of-control of high density water-based drilling fluid is the increase of inferior solid phase content. Inferior solid phase is dispersed in high density water-based drilling fluid,which enhances the system architecture,resulting in increased drilling fluid viscosity and higher shearing force. Based on the principle of viscosity reduction by competitive adsorption,WNTHIN,a low molecular weight polymer viscosity reducer was synthesized with 2-acrylamide-2-methylpropanesulfonic acid,styrene,maleic anhydride,N and N-dimethylacrylamide in a molar ratio of 1∶2∶1∶1.Test results of the viscosity reducer show that WNTHIN can significantly reduce the viscosity and shearing force of high density potassium polysulfonate water-based drilling fluid with a density of 2.40 g/cm3,with plastic viscosity reduced by 42.85%,static shearing force reduced by 51.35%,and the recommended WNTHIN dosage addition is 1.5%. The field application of WNTHIN in a well in Penglai Gas Field showed improved rheology of high density potassium polysulfonate water-based drilling fluid. The plastic viscosity dropped from 58 mPa·s to 30 mPa·s,the yield point dropped from 29 Pa to 14 Pa,and the 10 min static shearing force dropped from 28 Pa to 16 Pa. The performance of the high density water-based drilling fluid has been improved to meet the technical requirements for safe drilling in deep wells. 

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    Research and Application Progress of Nanofluid for Enhanced Oil Recovery

    LIANG Tuo, YANG Changhua, ZHANG Yanjun, LI Pan, QU Ming, HOU Jirui
    Xinjiang Oil & Gas    2023, 19 (4): 29-41.   DOI: 10.12388/j.issn.1673-2677.2023.04.004
    Abstract172)      PDF (5519KB)(168)       Save

    In view of the limitations of traditional polymer and surfactant solutions in enhancing oil recovery,such as low viscosity retention and large adsorption loss,this paper examines the potential use of nanofluids for enhanced oil recovery and discusses recent research in this field. First,the synthesis of nanomaterials is described,and the methods used for evaluation of the stability of nanofluids in enhanced oil recovery in the field are summarized. Second,six mechanisms by which nanofluids enhance oil recovery are reviewed. These are:reducing interfacial tension,changing wettability,reducing crude viscosity,improving foam stability,structural disjoining pressure,and reducing pressure and increasing injection. Third,the use of nanofluids for enhanced oil recovery in the field is investigated. The “bottleneck” issues that limit the large-scale application of nanofluids in oilfields are also described. For example,there are currently no nanofluid flooding systems available for efficient development of unconventional reservoirs. Furthermore,there has been insufficient theoretical and technical discussion and research. More integrated research is required on inter-related matters such as the development of nanofluids containing two-dimensional nanosheets,determination of the mechanisms for enhanced oil recovery,and field pilot testing of the process. Finally,a direction for the practical introduction and application of nanofluids is proposed.

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    Research Status and Development Proposal of ROP Improvement Technology with Percussion Rock-Breaking Method
    LI Gensheng, MU Zongjie, TIAN Shouceng, HUANG Zhongwei, SUN Zhaowei
    Xinjiang Oil & Gas    2024, 20 (1): 1-12.   DOI: 10.12388/j.issn.1673-2677.2024.01.001
    Abstract170)      PDF (7836KB)(182)       Save

    Enhancing the rate of penetration (ROP) is crucial for optimizing the efficiency of oil and gas development and deep exploration in China and ensuring national energy security. The percussion rock-breaking drilling technology has been applied in oil fields at home and abroad,resulting in significant improvements in ROP. Further research efforts are expected to address the technical challenges of low drilling footage and limited ROP enhancements encountered during deep exploration of hard rock formations with high temperature and pressure. This paper presents and analyzes the practice and development trends of the drill bit percussion rock-breaking drilling technology assisted by axial percussion,torsional percussion,and axial-torsional coupled percussion. It illustrates that the percussion-assisted drill bit rock-breaking mechanism is the core of percussion rock-breaking ROP improvement technology. This paper also reviews the scientific advancements made by domestic and overseas research scholars in physical experiments,theoretical modeling,and numerical simulation of percussion-assisted drill bit rock-breaking. In addition,it offers relevant proposals for the development of percussion rock-breaking ROP improvement technology,i.e. advancing research on material structure optimization design,intelligent control,integration of multiple technologies,and optimization of well applications. This is expected to provide valuable insights for enhancing the drilling efficiency in energy development of our country.

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    Indentification for Leakage Risks of Crude Oil Tanks Based on Fault Tree Analytic Hierarchy Process
    ZHAO Yao, LIU Chuang, LIU Zhenyi, LI Pengliang
    Xinjiang Oil & Gas    2023, 19 (3): 80-85.   DOI: 10.12388/j.issn.1673-2677.2023.03.012
    Abstract147)      PDF (789KB)(38)       Save

    Leakage of crude oil storage tanks can cause serious consequences,and risk identification and analysis of crude oil storage tank leakage is an important part of tank farm safety management. Based on the fault tree analysis (FTA) model and analytical hierarchical process (AHP),this research identified and incorporated a total of 18 basic events,and quantified the structural importance of each basic event through the minimum cut set. The judgment factor was determined as per the structural importance,and then a judgment matrix was constructed to analyze the risks of tank leakage. The analysis results showed that valve failure,design defects,overfilling,tank defects and overhaul operations are the main contributors to tank leakage risks. The findings of this research provide a theoretical basis for tank leakage risk prevention and control. The FTA-AHP method was also proved to be able to objectively analyze the risk of tank leakage and provide theoretical support for the daily safety management of storage tanks.

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    Development Status of Wellbore Integrity Inspection Technology for Deep Strata and Deep Wells
    SONG Xuefeng , LI Zhibin, , LIU Jinming , WANG Jiangshuai , DING Yida , QIAN Xuesen
    Xinjiang Oil & Gas    2024, 20 (4): 8-18.   DOI: 10.12388/j.issn.1673-2677.2024.04.002
    Abstract128)      PDF (2630KB)(64)       Save

    As the development of oil and gas resources is continuously advancing toward deep water areas,deep and ultra-deep strata,complex geology and extreme wellbore conditions pose great challenges to the safe and stable production of oil and gas wells. Conventional wireline logging technology and casing packer leak detection technology can meet the technical requirements of wellbore integrity inspection,but they both require to shutdown wells and the costs of joint inspection are high. In recent years,the application of fiber optic sensing in petroleum industry has become increasingly widespread,opening up new ideas for real-time monitoring of wellbore integrity. By systematically summarizing the current development status of wellbore integrity inspection,the following prospects are made:(1) Permanently or semi-permanently placing optical cables in oil wells enables monitoring the temperature field,pressure field,stress field,sound waves,vibration,and fluids inside the wellbore in real time to provide direct data for evaluating the integrity status of oil and gas wells.(2) Fiber optic sensing technologies such as DTS and DAS are characterized by continuous,real-time and distributed measurement,for which it is preferred to place them during the well construction to deliver full lifecycle monitoring of oil and gas wells. However,the overall cost of fiber optic laying is relatively high,and the fiber optic layout method needs to consider the impact of pipe string insertion and cementing perforation operations. The fiber optic winding method and light source scattering type also have an impact on optical signal transmission and signal-to-noise ratio. Corresponding measures need to be taken to optimize the signal-to-noise ratio,improve the measurement accuracy and stability of the sensor.(3) Processing of fiber optic signals mostly relies on empirical methods determining the signal range in accordance with laboratory simulation experiments. However,considerable differences exist between the laboratory environment and the downhole environment. Therefore,it is still necessary to conduct wellbore experiments and establish measurement interpretation models based on the actual wellbore environment.

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    The Lost Circulation Mechanism in Formations Prone to Lost Circulation at Misui Block in Changqing Oilfield

    PENG Lei, LUO Jiangwei, ZHAO Hongbo, LE Lu, BIAN Jing, DONG Jingnan
    Xinjiang Oil & Gas    2023, 19 (4): 10-19.   DOI: 10.12388/j.issn.1673-2677.2023.04.002
    Abstract124)      PDF (8824KB)(98)       Save

    Rich in natural gas resources,Misui Block is a key strategic area for accelerating the production of Changqing Oilfield. However,the frequent occurrence of lost circulation in recent years has seriously restricted improvement of cost-efficiency. Therefore,to curb the occurrence of well lost circulation,the lost circulation mechanism in this area has been studied through multi-scale quantitative experiment on rock physical property,microelectrode imaging logging observation and geo-mechanical profile analysis of wells. The results show that the thief zones in Misui Block are mainly in Liujiagou and Shiqianfeng Formations,which have large numbers of micro- and nano-scale fractures. The average calculated dynamic Yang's modulus of the cores from these formations are 17.94 GPa and 8.47 GPa,respectively,and the average dynamic Poisson's ratios are 0.394 and 0.064,respectively. The clay mineral content of Liujiagou Formation is more than 50%,and the brittle mineral content of Shiqianfeng Formation is as high as 72%. The imaging logging map shows that the area contains tensile fractures. The single well geo-mechanical profile reveals a low-pressure area in the thief zone,where the density of drilling fluid is 1.18 g/cm3. Finally,analysis shows that the high contents of clay and brittle minerals in the formation caused both hydration fractures and structural fractures,with low formation pressure causing drilling fluid to flow into natural fractures,eventually resulting in lost circulation. The research results not only reveal the lost circulation mechanism at Misui Block,but also provide technical guidance for selecting plugging methods and reducing well lost circulations at Misui Block.

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    Xinjiang Oil & Gas    2025, 21 (1): 0-.  
    Abstract123)      PDF (13664KB)(51)       Save
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    Status and Development Trend of Molten Salt Thermal Storage Technology Based on Photothermal Technology
    DUAN Shengnan, MA Nengliang, CHEN Xiangyu, DUAN Zidan, CHEN Bairong, WANG Zhiqiang
    Xinjiang Oil & Gas    2024, 20 (2): 87-.   DOI: 10.12388/j.issn.1673-2677.2024.02.011
    Abstract121)      PDF (1771KB)(42)       Save

    In addressing the problems of intermittency and instability in the conventional utilization of solar energy,this paper introduces the research progress of the photothermal technology applied in photothermal power generation and direct solar thermal utilization for stable solar heat supply by employing heat storage systems,and summarizes the classification methods and application scenarios of current heat storage technologies. This study reviews the technical principles and research progress of the mainstream molten salt heat storage systems (carbonate,chloride,fluoride and nitrate),pointing out the advantages and technical problems of different molten salt thermal storage systems. Aiming at the core of the molten salt thermal storage technology,it summarizes the research status and process flow of photothermal technology in different scenarios. This paper also generalizes the development trends of molten salt thermal storage systems in the photothermal field. First,suitable heat collection modes are selected according to application scenarios,and the capacity configuration and coordination control of solar heat collection and molten salt thermal storage are optimized. Second,molten salt with lower melting points,wider liquid temperature range,and low corrosion is developed to improve the applicability of molten salt thermal storage. Third,the operation safety and stability of the molten salt energy storage system can be ensured while costs are lowered. This provides a reference for the future application and development of the molten salt thermal storage technology.

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    Practice and Understanding of Volume Fracturing Technology for Horizontal Wells in Jimsar Shale Oil Reservoir

    XU Jiangwen, WANG Mingxing, WANG Junchao, SUN Haoran, WANG Liang
    Xinjiang Oil & Gas    2024, 20 (3): 23-30.   DOI: 10.12388/j.issn.1673-2677.2024.03.003
    Abstract119)      PDF (790KB)(86)       Save

    Addressing Jimsar shale oil reservoir,this study aims to enhance fracture-controlled reserves by conducting theoretical research and technical practices. Focused on four key aspects—fracture network design,construction,proppant effectiveness,and the enhancement of in-situ oil mobility,three generations of technological advancements have been realized. Fundamental theories regarding the effective propagation of hydraulic fracture in thin interlayers and key technologies such as multi-cluster fracturing within a stage and the use of cost-effective materials have been mastered. An integrated horizontal well volume fracturing technology system centered on fracture-matrix matching,precise stimulation,multi-scale proppant support,and CO2 prepad injection has been developed. The key technical indicators of fracturing have reached the advanced domestic level,supporting the large-scale and efficient development of Jimsar shale oil. In 2023,the oil production of Jimsar shale oil surpassed 60×104 t,with a consecutive annual production increase of 10×104 t in the block for three years. This achievement has provided robust technical support for the establishment of China's first national continental shale oil demonstration zone by 2025 and serves as a reference for optimizing shale oil development technologies in other regions of China.

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    Concentrated Solar Steam Generation Technology Enables Low Carbon Shallow Super-Heavy Oil Production

    FAN Yuxin, LI Hongzhou, DUAN Shengnan, GU Pengcheng, REN Ning
    Xinjiang Oil & Gas    2023, 19 (4): 82-87.   DOI: 10.12388/j.issn.1673-2677.2023.04.011
    Abstract117)      PDF (1762KB)(40)       Save

    PetroChina Xinjiang Oilfield Company is carrying out a pilot test of concentrated solar power direct steam generation,in conjunction with existing gas-fired steam boilers,to produce low-carbon,high-quality steam for super-heavy oil production using SAGD technology. This has exemplary significance for the integration of oil and gas field exploration and development using renewable energy technology. Under the double carbon initiative,Xinjiang Oilfield is facing the challenge of reducing natural gas consumption and CO2 emission while maintaining super-heavy oil production. Through combining solar energy concentrating and heating technology,green electricity + electrode molten salt heating technology,and high-temperature heat storage technology,renewable energy supply configuration schemes for different scenarios are proposed for the use of steam injection in shallow heavy oil exploitation,which will provide a specific road map and solution for the scale application of concentrating solar power technology in the heavy-oil operation areas of Xinjiang Oilfield. The schemes will reduce self-consumption of natural gas and provide low-cost steam,and has guiding significance for low carbon,sustainable exploration and development of heavy-oil fields.

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    Analysis of the Effects for Reamer Size under Different Operation Conditions:a Case Study of Well H101 in the Southern Margin of Junggar Basin

    GAN Quan, ZHANG Maolin, ZHANG Chen, WEI Qiang, LI Bingqing, ZHANG Dong
    Xinjiang Oil & Gas    2023, 19 (3): 10-20.   DOI: 10.12388/j.issn.1673-2677.2023.03.002
    Abstract114)      PDF (5579KB)(74)       Save

    The determination of the reamer size(the desirable reamed borehole size) is a global challenge for research on reaming in drilling. To ensure smooth drilling and cementing of reamed borehole sections,an in-depth case study of Well H101 drilled in the southern margin of Junggar Basin was performed to identify the affecting patterns of the reamed borehole size on drilling,tripping and cementing operations. The requirements for the reamer size were analyzed from perspectives of the drilling tool bending deformation,pump rate optimization,BHA vibration,swab and surge pressure during tripping and fluid density window,surge pressure of running liners,equivalent circulating density(ECD) during cementing,and wellbore integrity incorporating wellbore curvature,and the impacts of changes in casing sizes on cementing of the reamed borehole section were investigated. Finally,the above analyses were combined with a mathematical statistical approach to comprehensively determine the reamer size. The determined reamer size was applied to Well H101 and analogous wells in the southern margin of Junggar Basin,which were all found with smooth drilling operations after reaming,and moreover,Well H101 delivered a daily penetration of 101 m for the reamed borehole section. The presented method and strategy for the reamer size optimization incorporate more factors and are more reliable. They provide important references for determining the reamer size of to-be-reamed wells. 

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    Design of Shaped Cutter PDC Bit for Deep Hard Plastic Mudstone

    LIU Wei, FENG Chaochao, WAN Xuxin, ZHANG Zengbao, WEI Jiusen, GAO Deli
    Xinjiang Oil & Gas    2023, 19 (3): 1-9.   DOI: 10.12388/j.issn.1673-2677.2023.03.001
    Abstract113)      PDF (7535KB)(45)       Save

    With oil and gas exploration and development approaching the deep-burial,deep-water and unconventional fields,the encountered formations become increasingly complex. Deep mudstone formations exhibit strong hard plastic characteristics during drilling,resulting in difficulties in penetrating of cutters into formations and low rates of penetration (ROP). Given the challenge of improving ROP in hard plastic mudstone,rock-breaking simulation tests of PDC (Polycrystalline Diamond Compact) cutters were conducted for hard plastic formations,and the rock-breaking effects of various shaped cutters were analyzed. The results indicated that the 3D-shaped cutter exhibits the best rock-breaking efficiency and certain durability: it delivers a maximum ROP improvement of 116.4% in the hard plastic mudstone in Shengli Luojia Oilfield. Furthermore,a staggered cutter arrangement design,combining axe-shaped and 3D-shaped cutters,was proposed for drilling deep and complex formations,like sand-mudstone interbedding formations,which delivers the highest ROP increment of  215.7% in Yongjin Oilfield in Junggar Basin. Additionally,potential measures for enhancing ROP in hard plastic mudstone were discussed. The design principles of "sharp breakthrough,plane advancing and intensive scraping with small-diameter cutters" are recommended to improve the drilling efficiency. The research findings provide valuable insights for optimizing the design of PDC bits for hard plastic mudstone.

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    Use of Metaverse Technology Clusters and Quantum Computing in CCUS:Research Status and Trends#br#
    LUO Ling , LI Yichang , WEI Liyao
    Xinjiang Oil & Gas    2023, 19 (3): 86-94.   DOI: 10.12388/j.issn.1673-2677.2023.03.013
    Abstract109)      PDF (2713KB)(42)       Save

    The metaverse represents the next generation of internet and is also an immersive virtual world connected to the real world on which it is having a profound effect. It is capable,for example,of real time rendering of digital twin scenarios and high-precision simulations that follow the laws of physics. Carbon Capture,Utilization,and Storage (CCUS) has come to be regarded as a critical core technology for China to achieve its double carbon goal. Compared with conventional Carbon Capture and Storage (CCS) technology,it offers tangible economic benefits and practical operability. The metaverse can energize every aspect of CCUS. However,current CCUS engineering technology is not standardized,which means high industrialization costs. Our analysis of the current development status of CCUS technology at home and abroad reveals that machine learning based on supervised and unsupervised algorithms can play a huge role in CO2 capture using adsorption techniques;in particular on the selection of adsorbent materials. In addition,process simulation and optimization using quantum computing offers a lower cost option for CO2 capture than the technologies currently in use. This paper proposes an intelligent,integrated,on and offline management system—using metaverse technology clusters (particularly machine learning—as a vision for the future to solve the industrialization issues facing CCUS and help to achieve its large scale application.

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    Non-Uniform Perforation to Balance Multi-Cluster Fractures Propagation and Parameter Optimization
    SHENG Mao , DENG Chao , LI Jie , GU Mingzhe , WANG Tianyu , TIAN Shouceng,
    Xinjiang Oil & Gas    2024, 20 (3): 54-63.   DOI: 10.12388/j.issn.1673-2677.2024.03.007
    Abstract109)      PDF (5659KB)(68)       Save

    Multi-cluster perforation staged fracturing of horizontal well has become one of the key technologies for completion and stimulation in unconventional oil and gas reservoirs. However,the fractures of the central perforation clusters in each fracturing stage are significant affected by stress interference from the fractures of heel and toe clusters,leading to substantial propagation resistance of the central cluster fractures. This is a major cause of the unbalanced propagation of multi-cluster fractures. This study optimized the design of non-uniform perforation distribution pattern between clusters to regulate the perforation parameters,balance the fluid distribution among clusters,mitigate the stress interference between fractures,and promote the balanced propagation of fractures. Therefore,a multi-stage,multi-cluster fracture propagation model that accounts for stress superposition between stages/clusters was established. The model was used to compare and analyze the fracture propagation patterns and mechanisms of spindle-shaped,sloped and uniform perforating patterns. The difference in fracture length and height propagation morphology was utilized to assess the equilibrium of fracture propagation. The perforation distribution pattern was optimized,and an orthogonal test was designed to refine the parameters of non-uniform perforation distribution pattern. The findings indicate that under typical shale oil reservoir conditions,the spindle-shaped perforation pattern achieves the best fracture propagation equilibrium,followed by uniform pattern and then the sloped pattern. The mechanism is that,with the spindle-shaped perforation pattern,the clusters at both ends have a perforation friction 1.4~16.7 times greater than that of the central clusters,reducing the stress interference from the heel and toe fractures on the central-cluster fractures. This results in an increased fluid inflow distribution in the central clusters,enhancing the fracture propagation equilibrium by 17.2 % compared to the uniform pattern. Conversely,the sloped perforation pattern,with over 35% of the holes concentrated at the toe cluster and accounting for 49.3 % of the fluid inflow,exerts a significant squeezing effect on the central cluster fractures,which is counterproductive to achieving a balanced fracture propagation. The optimization of the spindle-shaped perforation parameters reveals that an fracture propagation equilibrium is achieved with a total of 49 holes,a perforation diameter of 10 mm,and an end-cluster perforation proportion of 24.5%. The research results are expected to offer an effective approach for the design of non-uniform perforation in multi-cluster fracturing for unconventional oil and gas reservoirs. 

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    Multi-Field Coupling Analysis of Wellbore Instability in Hutubi Anticline While Using Water-Based Drilling Fluid

    SONG Xianzhi, GUO Yong, XIANG Dongmei, JU Pengfei, TAN Qiang, LIU Wei
    Xinjiang Oil & Gas    2023, 19 (4): 1-9.   DOI: 10.12388/j.issn.1673-2677.2023.04.001
    Abstract107)      PDF (3894KB)(60)       Save

    Complex problems,such as HTHP,wellbore collapse,and lost circulation were encountered during drilling Hutubi Anticline. The fabric,mechanical properties,and in-situ stress state of the troublesome medium-deep shale formation were analyzed to determine the countermeasures necessary to stabilize the borehole and reduce risk. A multi-field calculation model for collapse pressure was established linking mechanical factors,drilling fluid chemistry,and fluid seepage. The mechanism of wellbore instability when using water-based drilling fluid in the middle-deep shale formation of Hutubi anticline was identified. The results indicate that the montmorillonite content of the illite-smectite mixed layers in the mudstone in Paleogene Anjihaihe-Ziniquanzi Formation (which collapses readily) exceeds 35%. The formation exhibits moderate expansion and high dispersion,with water expansion rate and recovery rate both being less than 10%. The formation strength also shows anisotropic properties. The mudstone in Cretaceous Hutubihe-Qingshuihe Formation shows reduced swelling and increased hardness and brittleness. Hutubi Anticline is subject to significant tectonic stress,with the maximum horizontal principal stress being equivalent to nearly 2.50 g/cm3,which is higher than the overburden pressure. Applying the multi-field coupling model indicates that the main causes of wellbore instability are seepage of drilling fluid along cracks,hydration of mudstone after contact with drilling fluid,and insufficient effective mechanical support of drilling fluid for the wellbore. The collapse pressure calculated using the multi-field coupling model is 0.05-0.25 g/cm3 higher than when only considering mechanical factors. It was established that the wellbore can be kept stable by maintaining the sealing ability of the drilling fluid to the fractured formation,preventing contact with easily hydrated mudstone during drilling,and increasing the density of the drilling fluid to slightly higher than the collapse pressure.

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    Numerical Simulation of the Pressure Law of Energy Charging and Permeability Enhancement in Low Permeability Reservoirs

    ZHU Zheng, DANG Hailong, CUI Pengxing, DANG Kaiyan, BAI Pu, ZHAO Yining
    Xinjiang Oil & Gas    2023, 19 (4): 56-62.   DOI: 10.12388/j.issn.1673-2677.2023.04.007
    Abstract103)      PDF (6406KB)(75)       Save

    A number of problems have been experienced with water injection in Yanchang Oilfield,such as high-pressure injection failure,poor flooding effect,and rapid increase of water cut during injection. An innovative method for energy charging and permeability enhancement is proposed to address these issues. Numerical reservoir simulation is used to study the evolution of fractures,matrix pressure,and bottom hole pressure propagation during injection and well shut in. The influence of injection volume on fracturing effect is also analyzed. It is found that,during the injection stage,rapid injection of fluid increases the pressure in the fracture,with the injected fluid passing through the main fracture to the tips of the fractures. The pressure increase mainly occurs around the fracture itself,with little change in the matrix pressure. In shut in stage,as shut in time increases,the matrix pressure in the fracture and near-fracture zone initially decreases rapidly and then tends to become stable after a certain time. If the distance from the fracture is more than 30 m,the matrix pressure first increases and then decreases with the increase of shut in time. The bottom hole pressure also declines rapidly in the early stage of shut in with the rate of decline slowing in the later stage. The greater the injection volume,the higher the formation energy. Analysis of the effect of energy charging and permeability enhancement in field applications for low permeability reservoirs shows remarkable increases in pressure and oil production. This provides a valuable reference for the development of energy charging and permeability enhancement in similar reservoirs.

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    Energy Conservation and Consumption Reduction Technology of Gas Extraction System in Hutubi Gas Storage
    MA Zenghui, ZHAO Yida, CHEN Ligang, HE Lin, ZHU Huan, BAI Bofeng
    Xinjiang Oil & Gas    2024, 20 (1): 88-94.   DOI: 10.12388/j.issn.1673-2677.2024.01.011
    Abstract101)      PDF (1756KB)(44)       Save

    Given the current situation that some operating parameters of the gas extraction system in Hutubi gas storage deviate from the optimal value to cause low energy-saving efficiency,the energy efficiency of the gas extraction system is analyzed through pinch analysis and exergy analysis methods. A simulation study is performed based on HYSYS software,giving rise to the scheme of energy conservation and consumption reduction. The scheme mainly includes the selection of the gas-gas heat exchanger,the optimization of the glycol-rich liquid inlet temperature,the optimization of the reflux ratio of the regenerator,and the optimization of the phase-change furnace. The calculation model between the inlet pressure and J-T valve back pressure and the theoretical KA value of the gas-gas heat exchanger is established to optimize the selection of the heat exchanger. The optimum inlet temperature of the glycol-rich liquid is determined to be 67 ℃,and the reflux ratio of the regenerator is 0.06. During the operation of the top condenser of the regenerator,the consumption of glycol can be reduced by 84.6%. The energy consumption of the system can be reduced by 9.0% by using the waste heat of the exhaust gas from the regenerator to preheat the external transmission gas. This optimization scheme effectively reduces the total energy consumption of the gas extraction system with minimum alteration.

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    Key Technologies and Practice of Shale Oil Cost-Effective Development in Jimsar Sag,Junggar Basin

    QI Hongyan, WU Chengmei, HU Ke, CHEN Yiwei, XU Tianlu, WANG Yongjiao
    Xinjiang Oil & Gas    2024, 20 (3): 15-22.   DOI: 10.12388/j.issn.1673-2677.2024.03.002
    Abstract97)      PDF (2526KB)(61)       Save

    Xinjiang Jimsar Shale Oil Demonstration Area is the first national-level continental shale oil demonstration project,located in Jimsar Sag,Junggar Basin,China. The target layer is Permian Lucaogou Formation. After ten years of exploration and development,with the obtained abundant production and geological data of the reservoir and deepened geological understanding,the corresponding exploration and development technologies become fairly mature. The fine 3D seismic survey with broadband excitation and well-surface integrated acquisition improves the geological understanding. The fine characterization and classification evaluation techniques of shale oil sweet spots provide a basis for development deployment. The comprehensive mud logging technology of "gold targets" improves the target-layer drilling ratio that is fundamental for delivering high stable production from horizontal wells. The customized fracturing technology of "complex fracture networks" provides an effective means for the efficient development of shale oil. The production capacity of horizontal wells is fully exploited by the flowback and production scheme optimization technique. The marketization has greatly reduced costs and improved both quality and efficiency. The cost-effective development technology system of Jimsar shale oil provides references for the efficient exploration and development of shale oil in China.

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    CO2 Flooding Connectivity Characteristics of the Strong Water-Sensitive Conglomerate Reservoir in Xinjiang Oilfield
    CHEN Shengen, XU Jinshan, ZHANG Xin, WANG Rui, ZHANG Liwei, LI Haifu
    Xinjiang Oil & Gas    2024, 20 (1): 44-51.   DOI: 10.12388/j.issn.1673-2677.2024.01.006
    Abstract96)      PDF (2075KB)(47)       Save

    Clarifying the connectivity characteristics between injection and production wells in CO2 flooding reservoirs can provide essential support for the subsequent implementation of CO2 flooding technology to improve sweep efficiency. With a strong water-sensitive conglomerate reservoir in Xinjiang Oilfield as the research object,this paper specifies the key parameters for determination of injection and production connectivity through the analysis of injection and production data. It designs the evaluation coefficient C after presetting the proportion of key parameters,and confirms the connectivity between injection and production wells under different ranges of C value,thus establishing a connectivity evaluation method for the strong water-sensitive conglomerate reservoir. This method can be used to judge weak,medium,or strong connectivity between injection and production wells in this area and analyze the main controlling factors of different connectivity characteristics to form targeted treatment measures. The study shows that the key parameters for determination of injection and production connectivity are oil production rate,tubing pressure,and the gas component of production wells. When the C value is greater than 8,the injection and production wells have strong connectivity;between 3 and 8,the injection and production wells have medium connectivity;and when less than 3,the injection and production wells have weak connectivity. According to the statistical injection and production data of the whole area and the C value,the connectivity between injection and production wells in the block presents two apparent characteristics. First,the connectivity between injection and production wells has directionality. The medium and strong connectivity is mainly northwest,but the local connectivity has specific differences,primarily affected by the structure and early water flooding. Second,the connectivity has regional characteristics and is better in the northeast region of the block center. Among the 22 wells in the area,14 wells show strong connectivity,accounting for 63.6%,mainly affected by the difference in formation permeability and the amount of carbon injection. According to the results of injection and production connectivity,it is suggested to implement classified management of the various connected wells in the area,huff and puff for wells with weak connectivity in the marginal area,small-scale fracturing for wells with weak connectivity in the core area,and channeling sealing and profile control for wells with strong connectivity. This study can provide a reference for the efficient development of strong water-sensitive conglomerate reservoirs by CO2 flooding after water injection.

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    Research Status of Wellbore Stabilization Drilling Fluid Materials in Complex Shale Formations
    HUANG Xianbin, , ZHANG Xuehao, , YUAN Zhenhang, , ZHANG Yang,
    Xinjiang Oil & Gas    2024, 20 (3): 46-53.   DOI: 10.12388/j.issn.1673-2677.2024.03.006
    Abstract96)      PDF (1203KB)(50)       Save

    In response to the frequent wellbore instability issues encountered during drilling operations in complex shale formations,the drilling fluid technologies aimed at wellbore stabilization have been developed at home and abroad. These include shale hydration inhibition,formation pore plugging,and chemical wall strengthening techniques. Despite these advancements,existing methods have limitations in curbing the surface hydration of shale,and the effect of rapid plugging and wall strengthening agent is considerably reduced under high temperature conditions,making it challenging to address wellbore instability. This paper offers a comprehensive review of the research work on drilling fluid materials for wellbore stability in complex shale formations. By analyzing the current state of research,it elucidates the mechanism of various drilling fluid materials,including shale hydration inhibitors,plugging agents,and chemical wall strengthening agents. It also discusses the strengths and limitations of different types of wellbore stabilization materials. This paper highlights the need for fundamental theoretical research into shale hydration,the development of novel nanomaterials that are stable and effective under high temperature and high salinity conditions,and the establishment of evaluation methods for chemical wall strengthening agents that can simulate downhole conditions. These areas are identified as key focal points and challenges for future research in the field of drilling fluid materials and technologies for wellbore stabilization in complex shale formations. This paper concludes with an outlook on the future development directions for these technologies and materials.

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    Fracture Propagation Law of Hydraulic Fracturing in High-Salinity Reservoir of Fengcheng Formation in Mahu #br#

    PAN Liyan, HAO Lihua, LIU Kaixin, SUN Xize, ZHU Zhenlong, ZHAO Yanxin,
    Xinjiang Oil & Gas    2023, 19 (4): 20-28.   DOI: 10.12388/j.issn.1673-2677.2023.04.003
    Abstract95)      PDF (2886KB)(83)       Save

    The high salt content of Fengcheng Formation in Mahu leads to high operating pressures, difficulty in fracture propagation when penetrating salt layers, and increased difficulty in adding proppant. True triaxial fracturing experiments are carried out on equivalent salt-bearing rock samples prepared according to similarity criteria, and fracture propagation in salt-bearing reservoirs is numerically simulated using the finite element and cohesive element methods. The influence of salt content, viscosity, pump rate, and other factors on fracture propagation is explored. The results show that the fracture opening pressure of salt-bearing reservoirs is greater than that of conventional sandstone reservoirs, and their plasticity is stronger. The existence of pure salt interlayers hinders the longitudinal propagation of fractures. The lower the fluid viscosity , the stronger the dissolution of the salt-bearing reservoir and the lower the operating pressure. The higher the pump rate, the higher the fracturing friction and the operating pressure. In field, high viscosity fluid (120 mPa·s) with clean water and high pump rate (5 m3/min per single cluster) have been adopted to achieve effective penetration into pure salt barriers and form wider fractures. These results have important guiding significance for the stimulation of salt-bearing reservoirs in Mahu area.

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    A Machine Learning-Based Bridging Particle Size Recommendation Method for Lost Circulation Control

    LIU Fan, LIU Yushuang, ZHANG Zhen, LI Yongjian, LIU Ce, MA Zhihu,
    Xinjiang Oil & Gas    2024, 20 (1): 13-20.   DOI: 10.12388/j.issn.1673-2677.2024.01.002
    Abstract93)      PDF (3565KB)(68)       Save

    Lost circulation is a key technical challenge in oil and gas exploration,and bridge plugging is the most commonly used method for lost circulation control. As an important parameter,the size of bridging particles directly affects the plugging. At present,the size selection mainly relies on experience,lacking a scientific and effective method. In light of this,this paper investigates a particle size recommendation method for lost circulation control based on machine learning algorithms. The basic data used for this method are well-logging,mud logging,and lost circulation control data from 126 completed wells in Kuqa piedmont area of Tarim Basin. The input layer adopts 23 main parameters screened based on the Pearson algorithm,and the output layer is in 4 bridging particle size ranges of 0-750 μm,750-1 500 μm,1 500-4 000 μm and>4 000 μm. 10 commonly used machine learning algorithms are trained and tested to determine the accuracy of three types of datasets:well logging data,mud logging data,and combination of the former two types. It is found that the scores of each algorithm for the well logging + mud logging dataset are generally higher than those for the well logging and mud logging datasets. For the combined dataset,the support vector machine and extremely randomized trees algorithms have the highest F1 scores of above 0.9. The bridging particle size recommendation model based on the support vector machine and extremely randomized trees algorithms is validated twice on a well in Kuqa piedmont area. The predicted results of bridging particle size of the two algorithm models are consistent with the actual bridging effect in the field. This method exhibits good application prospects in the scientific optimization of bridging particle size.

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    Performance Evaluation of the Cement Sheath in Jimsar Shale Oil Wells

    WANG Dian, LI Jun, ZHANG Wei, LIAN Wei
    Xinjiang Oil & Gas    2023, 19 (4): 49-55.   DOI: 10.12388/j.issn.1673-2677.2023.04.006
    Abstract93)      PDF (1588KB)(50)       Save

    Hydraulic fracturing technology is an important method for increasing the production capacity of shale oil wells. The mechanical behavior of well cement sheath during fracturing has an important impact on the safety and efficiency of production. Based on the cement slurry system in Jimsar region,a cement specimen maintenance mold was designed as well as a cement bonding strength test program,maintaining the standard cylindrical specimen of cement and the set cement bond specimen. The uni/triaxial compression experiments were then carried out as well as the cyclic loading experiments and bonding strength experiments under simulated well bottom conditions to investigate the rules governing damage and destruction of cement bodies and cementing interface. The results show that under uniaxial compression,the set cement has significant elastic-brittle characteristics and that macroscopic cracks are formed in the cement body when it is damaged.The average Young's modulus of cement is 3.054 GPa and the average Poisson's ratio is 0.127. Under triaxial conditions,the strength and plasticity of the cement sheath are enhanced. During cyclic loading,there is a bilinear accumulation of cementite plastic deformation,with the amount of plastic deformation being positively correlated with the peak load. The plastic strain after 20 cycles increased from 0.24% to 2.46% when the peak load increased from 22.7 MPa to 53.2 MPa. The cement bonding strength is lower than 1 MPa,which is much lower than the body strength,and the bonding interface is a natural mechanical weak zone,representing a risk point for wellbore seal failure.

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    Xinjiang Oil & Gas    2023, 19 (3): 0-.  
    Abstract91)      PDF (13819KB)(91)       Save
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    Prediction of Bedding Fractures in Shale Reservoirs Based on Two-Step Matching Core-Logging-Seismic Information

    LI Jiacheng, TIAN Gang, WANG Junchao, ZHANG Teng, TONG Liang
    Xinjiang Oil & Gas    2024, 20 (1): 21-30.   DOI: 10.12388/j.issn.1673-2677.2024.01.003
    Abstract90)      PDF (10589KB)(39)       Save

    The key to breakthroughs in shale oil exploration and development lies in the characterization and prediction of reservoir bedding fractures. The complexity of its genetic mechanism and the diversity of influencing factors have led to bottlenecks in the prediction technique. Based on the identification of bedding fractures at core and thin section scale (~ mm),and evaluation of bedding fractures through resistivity imaging and at conventional logging scale (~ m),it is found that the bedding fractures in the sweet spot section of Lucaogou Formation in Jimsar Sag are the most developed in dolomite reservoirs,followed by dolomite siltstone and argillaceous siltstone. These fractures are predominantly found in the distribution area of tight reservoirs and exhibit a significant negative correlation with reservoir matrix porosity. Furthermore,combined with the lithology distribution predicted by 3D seismic data and the porosity distribution from inversion,this study investigates the technique for predicting bedding fractures in shale reservoirs by advancing sequentially through core-points,logging-lines,and seismic-surfaces using the well-seismic information scale matching technology. This method integrates the advantages of accurate core identification,high longitudinal resolution of logging curves,and strong lateral continuity of 3D seismic data. The verification conducted on 27 wells in the sweet spot section of the Lucaogou Formation in Jimsar Sag shows an average relative prediction error of 8%,indicating a satisfactory application effect. This technology can provide robust support for the exploration and development of shale oil in the Lucaogou Formation,and it also holds significant reference value for the evaluation of shale oil reservoirs in other basins.

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    Study on the Law of Wellbore Alkali-Salt Deposition in Fengcheng Formation  of Mahu Sag#br#
    WU Dingying , PU Di, , ZHENG Miao , YIN Jianyu , LUO Pingya , GUO Yongjun,
    Xinjiang Oil & Gas    2023, 19 (3): 42-48.   DOI: 10.12388/j.issn.1673-2677.2023.03.007
    Abstract89)      PDF (1744KB)(93)       Save

    The post-frac flowback and production of the alkali-salt layers of Fengcheng Formation in Mahu Sag suffer from wellbore salt deposition,but the salt deposition law remains unclear. Therefore,through static and dynamic salt precipitation evaluation experiments,the reservoir conditions affecting the salt precipitation rate and the impacts of flow rate and gas production on wellbore salt deposition in the production process are investigated to clarify the wellbore salt deposition law. The results show that the three typical salts,with their solubility from most to least sensitive to temperature,are sodium carbonate,sodium bicarbonate and sodium chloride. Moreover,the boundary conditions (total salinity and ion composition) and salt crystal types of salt crystal precipitation are defined for composite salt solutions with different compositions. Under the same salinity,the precipitation degrees of composite salts with different compositions are between those of the individual salt,and the priority orders of salt precipitation are sodium bicarbonate,sodium carbonate and sodium chloride,which is consistent with the change of solubility of various salts with temperature. With the increasing flow rate and gas production,the salt deposition first grows and then declines. The salt deposition peaks in the case of the daily liquid production of 40 m3/L and the gas-liquid ratio of 200 m3/L.The study on the salt deposition law in alkali-salt wells helps to set reasonable drainage parameters,delay the salt deposition during flowback,ensure the smooth completion of formation testing after fracturing,and provide a theoretical basis for on-site salt prevention measures in the later production from Fengcheng Formation alkali-salt layers.

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    Analysis of Factors Affecting the Productivity of Radial Multilateral Horizontal Wells in Low Permeability Reservoirs

    SUN Xize, YU Tianxi, Anivar·SHAYIMU, ZHENG Weijie, DING Kebao
    Xinjiang Oil & Gas    2023, 19 (3): 49-56.   DOI: 10.12388/j.issn.1673-2677.2023.03.008
    Abstract88)      PDF (3945KB)(55)       Save

    Radial multilateral horizontal well technology can be used to improve the productivity of low permeability reservoirs by drilling multilateral branches in the oil intervals of horizontal wellbores,which increases the oil displacement area. However,the factors affecting the productivity of radial multilateral horizontal wells are not clear and,to date,there has been little research on methods of prediction. This paper describes a numerical model for radial multilateral horizontal wells,using numerical simulation software COMSOL,and its application in evaluating the influence of factors such as reservoir and well type on well production. The mathematical model was solved using the finite element method and radial horizontal well output predicted using the material balance method. The focus of the study is to analyze the effects of changes in radial multilateral well parameters and formation heterogeneity on production behavior and transient pressure distribution. The results show that branch length has a significant effect on productivity,effectively expanding the control area. The number of branches,their angles,and formation heterogeneity,are found to be the principal controlling factors.

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    Xinjiang Oil & Gas    2024, 20 (1): 0-0.  
    Abstract88)      PDF (13817KB)(331)       Save
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    Applicability Evaluation of Tight Oil Reservoir Gas Channeling and Sweep Control System
    LI Junjian, XI Yilin, ZHANG Miao, ZANG Chuanzhen
    Xinjiang Oil & Gas    2024, 20 (1): 68-76.   DOI: 10.12388/j.issn.1673-2677.2024.01.009
    Abstract87)      PDF (1953KB)(37)       Save

    Tight oil reservoirs are widely distributed in China,with a large proportion of reserves and great development potential. These reservoirs have low matrix permeability and porosity,with fractures acting as main oil and gas flow channels,and gas injection is often used to recover such reservoirs. However,due to the cross-scale development of reservoir fractures and the influence of reservoir heterogeneity and viscous fingering,the technology of gas injection to improve oil recovery has limits. Gas channeling can easily occur in the presence of fractures and high permeability bands,causing many issues related to the energy supplement of formation. In this paper,foam and CO2-responsive gel were selected to prepare the gas channeling and sweep control system,and their performance and applicability in tight oil reservoirs were evaluated by physical experiment simulation. Commercial numerical simulation software was used to characterize CO2 huff-n-puff and underground gelling reaction. Through the numerical simulation of a tight oil reservoir in China,it is proved that the CO2-responsive gel has an obvious stimulation effect during huff-n-puff treatment,resulting in an increase in recovery rate by 3.1%. This research validates the promising application prospects of the CO2-responsive gel system in the development of tight oil reservoirs.

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    Design and Development of the High-Temperature High-Pressure Insert-Type Packer for Gas Injection#br#
    HUANG Xiaomeng, XIAO Guohua, WANG Lei, WANG Yuanzheng, TIAN Jingmeng, WANG Yao
    Xinjiang Oil & Gas    2023, 19 (3): 21-25.   DOI: 10.12388/j.issn.1673-2677.2023.03.003
    Abstract86)      PDF (2295KB)(33)       Save

    In order to solve the troublesome tubing and casing annulus pressure caused by sealing failure of the gas injection packer during high-pressure gas injection,a new insert-type high-temperature high-pressure gas injection packer was developed by optimizing the packer structure and sealing mechanism and elements. The integral insert sealing tubing is designed to reduce the connection parts and therefore,leakage risks. The sealing rings are integrated into the insert tubing body via the in-situ vulcanization to avoid damage to sealing rings due to string creep and improve the sealing effect and service life of the insert tubing. The gas-sealing rubber cylinder is adopted and equipped with split-open rigid support protectionto avoid damage to the rubber cylinder,improve the gas injection sealing performance and prolong the service life of the packer.The invented packer reduces the risks of casing annulus pressure,solves the potential safety hazards in high-pressure gas injection,and provides technical support for gas flooding in Jidong Oilfield.

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    Film-Forming Plugging Reservoir Protection Technology in Tangdong Evaluation and Appraisal Wells#br#
    ZHUO Lvyan , ZHAO Cheng , ZHANG Yi , Wang Yingbo , Dou Shuming , Wang Chao
    Xinjiang Oil & Gas    2023, 19 (3): 26-32.   DOI: 10.12388/j.issn.1673-2677.2023.03.004
    Abstract82)      PDF (697KB)(43)       Save

    Tangdong Block of Dagang Oilfield has complex geology. The main target layers are the third member of Dongying Formation and Shahejie Formation. The target layers are deeply buried and rather thick, and the damage mechanisms between the reservoirs are very different. The applications of fine calcium carbonate and plugging agents for drilling fluids in reservoir damage prevention present insufficient performance for exploration and appraisal wells in this block, due to the low technical adaptiveness to the reservoirs and inferior practice management. The core permeability recovery rate for the reservoirs is only 67.5%. According to the core sensitivity evaluation and casting thin section analysis results of Well Tangdong 9X6, a reservoir protection technology system was developed for the drilling of the Tangdong exploration and appraisal wells, according to the potential damage factors. The protection system adopts the film-forming plugging reservoir protection technology and combines the applications of the single-well multi-layer/multi-point design method. The efficient implementation of the developed technology system is ensured with the help of refined technology implementation management and high-quality real-time evaluation. The film-forming plugging reservoir protection technology was applied to five wells in this block. The dynamic fluid loss of drilling fluids was reduced by 25.7%, and the permeability recovery rate was increased by 13.1%.  All the five wells met the geological expectations. Two wells have delivered high production, with initial daily production of 61.3 t and 101.1 t, respectively, which indicates good performance.

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    Exploration of Nitrogen Injection Production Resuming Technology for Offshore Bottom Water Coning Gas Wells

    LI Chenhong, DING Yingnan, HE Xiuping, ZHONG Baoku, LIU Zixiong
    Xinjiang Oil & Gas    2023, 19 (3): 66-71.   DOI: 10.12388/j.issn.1673-2677.2023.03.010
    Abstract82)      PDF (2198KB)(32)       Save

    底水锥进会使气井产量快速递减和采出程度大幅下降,尤其在海上高采气速度下底水锥进影响更显著。为了能够使此类井成功复产,开展了注氮气压水锥研究和现场试验。通过数值模拟研究,确定了水锥面的物理形态,并据此优化氮气的注入量和焖井时间。A3井实施两轮次累计注入38×104 m3氮气。现场试验表明:通过高压注入氮气可以有效突破水锥面对气相的封堵,建立气相与井筒的通道。两轮次分别返排出10%~15%的氮气后,天然气的含量即可达100%,说明只需要较少的注入量即可突破水锥面;但底水能量强,现场处理能力有限,频繁更换生产制度导致大量产水,累计自喷15×104 m3天然气后停喷。在后期的治理中需要控制油嘴,防止井底流压波动加剧产水,影响复产效果。本次注氮气压水锥工艺探索对同类底水气藏的复产有一定的借鉴和指导意义。

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    Applications and Exploration of Intelligence Technology for CO2 Transportation Pipelines in the Background of Carbon Peak and Carbon Neutrality#br#
    MA Yun , ZHAO Li
    Xinjiang Oil & Gas    2024, 20 (4): 87-96.   DOI: 10.12388/j.issn.1673-2677.2024.04.011
    Abstract82)      PDF (662KB)(28)       Save

    CCUS (Carbon Capture,Utilization and Storage) is widely considered as an indispensable key technology for achieving the goals of global temperature control and China's vision of carbon neutrality,since it can effectively and significantly reduce industrial CO2 emissions. The transportation of CO2 from the source to the utilization site is a key link for achieving the technological goals of the CCUS industry. This paper mainly focuses on the pipeline transportation method and firstly outlines the development status of intelligent pipeline technology in both China and other countries. Then,the phase classification and related problems of CO2 transportation pipelines are addressed,and a problem-oriented investigation of the mechanism of deep fusion between artificial neural network models and pipeline corrosion rate prediction is presented. Moreover,the pipeline leak positioning principles and applications of distributed optical fiber,characteristic spectrum,and robot inspection technologies are clarified,and finally the development orientation of CO2 transportation pipeline intelligence is discussed. Comprehensive perception,centralized sharing,prediction and early-warning,and collaborative operation of CO2 pipeline data,driven by the business demand of CO2 transportation pipelines and delivered by pipeline transportation technology plus ICT technology,are believed to be the future trend of intelligent development of CO2 transportation pipelines,although no wide agreement has been reached yet. The findings of this research provide references for the sustained development and gradual application promotion of intelligent pipelines in the future.

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    Development and Evaluation of Block Silicone Oil Anti-Water Blocking Agent
    JIN Jiafeng, DENG Yan, HUANG Xianbin, WANG Jintang, LIU Kesong
    Xinjiang Oil & Gas    2023, 19 (3): 38-41.   DOI: 10.12388/j.issn.1673-2677.2023.03.006
    Abstract80)      PDF (597KB)(47)       Save

    To prevent the water block damage induced by any extraneous fluid's invasion during drilling and completion operations in low-permeability gas reservoirs,a high-performance anti-water blocking agent(FWB),which is composed of hydrogen-rich block silicone oil and some additives such as organosilicon surfactant and deformer,was developed for low-permeability gas reservoirs. The infrared spectroscopy was used to characterize the molecular structure of the block silicone oil,and a series of tests,which include surface tension test,contact angle test,core imbibition test,permeability recovery ratio test,and drilling fluid compatibility test,were conducted to comprehensively evaluate the performance of this anti-water blocking agent. The test results show that,at the mass concentration of 1%,it can dramatically reduce the surface tension of the aqueous phase to 22.28 mN/m,increase the contact angle of the aqueous phase from 29° to 120°,decrease the core imbibition amount by 69.2%,and improve the permeability recovery ratio to 89.3%,and that it has good compatibility with drilling fluids. This anti-water blocking agent can significantly reduce the water block damage during drilling and completion operations and provide effective protection for low-permeability oil and gas reservoirs. 

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    CO2-CH4 Gas Throttling and Hydrate Generation Characteristics

    XIONG Xiaoqin, AN Guoyu, LIAO Tao, LI Xinze
    Xinjiang Oil & Gas    2024, 20 (1): 61-67.   DOI: 10.12388/j.issn.1673-2677.2024.01.008
    Abstract80)      PDF (2714KB)(30)       Save

    In the process of CO2 flooding production and oil lifting,with the decrease of pressure,a large amount of associated gas will be separated from the produced liquid. In the associated gas,the content of CO2 is as high as 50%-90%. Compared with CH4,gaseous CO2 has a stronger throttling cooling effect,which may cause the generation of hydrate to block the pipeline,threatening the operation safety of the gathering and transportation system. The influence of CO2 content on the CO2-CH4 gas throttling and hydrate generation characteristics was studied using a high-pressure sapphire reactor. The results show that:When the initial pressure is high (16 MPa),the throttling effect coefficient Di of the mixture gas with the same CO2 proportion is about 1.3-5.4 ℃/MPa,and the incorporation of CH4 will enhance the throttling effect of the mixture gas,indicating that the high pressure section is mainly affected by the throttling effect of CH4;when the initial pressure is low (5 MPa,4 MPa),the throttling effect coefficient Di is about 3.4-11.9 ℃/MPa,and the incorporation of CH4 will weaken the throttling effect of the mixture gas,indicating that the low pressure section is mainly affected by the throttling effect of gaseous CO2. The higher the pressure at which CO2-CH4 gases with the same CO2 content are,the higher the temperature at which hydrates are generated,and the easier it is to generate hydrates. At the same pressure,the lower the CO2 content is,the lower the temperature at which hydrates are formed. When the CO2 content is 8%-100% and the pressure is 1.5-5 MPa,the hydrate generation temperature is 0.5~10 ℃. The comparison results between the experimental and software simulation data show that the PR equation of state has a high correlation for the calculation of CO2-CH4 throttling and hydrate generation characteristics. The research results can provide a reference for the selection of safe gathering and transportation process parameters.

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    Numerical Simulation of Nitrogen-Assisted VHSD Development in Old Super-Heavy Oil Reservoirs
    WANG Pan, LIU Yang, LIANG Xiangjin, ZHENG Aiping, QIN Ninghan, FENG Zhijun
    Xinjiang Oil & Gas    2024, 20 (1): 38-43.   DOI: 10.12388/j.issn.1673-2677.2024.01.005
    Abstract79)      PDF (4553KB)(40)       Save

    Changing over to Vertical-Horizonal well Steam Drive (VHSD) development pattern is becoming an important means for improving block production rate and recovery rate in old super-heavy oil reservoirs. Nitrogen-assisted VHSD can increase energy and pressure and form a heat insulating top layer,effectively solving the problems of pressure maintenance,low displacement pressure,and low steam chamber temperatures following huff-puff operations in old heavy oil reservoirs,saving steam volume,improving oil production levels and oil-steam ratio,and reducing carbon consumption. This paper examines a VHSD development unit in the Ninth Block of Karamay Oilfield. Numerical simulation is used to determine the influences of different parameters (nitrogen injection timing,injection pattern,injection amount) on pressure and energy increase,and on the establishment of heat insulating layers. Variations in recovery rates and accumulated injection-production indicators during VHSD development are also analyzed. The results show that nitrogen injection by slug can help to build a heat insulating layer in the initial stages of the transition to displacement and drainage. In field tests of this nitrogen-assisted VHSD approach,the oil-steam ratio of the study well group was increased by 0.025,and daily oil production was increased by 0.7 t,which are favorable results. This study provides a technical reference for efficient development using nitrogen-assisted VHSD in similar old heavy oil reservoirs.

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    Numerical Simulation for Peeling Failure of Cement Plug-Formation Interface in Plugged Section of Old Wells

    FU Pan, WANG Jiangshuai, LIU Tianen, XIA Yan, Deng Song, TANG Zheng
    Xinjiang Oil & Gas    2023, 19 (4): 69-74.   DOI: 10.12388/j.issn.1673-2677.2023.04.009
    Abstract78)      PDF (4278KB)(27)       Save

    Due to the small casing diameter and the insufficient gas tightness of casing coupling threads,the old well cannot be converted into an injection-production well for the underground gas storage. Therefore,the old wellbore must be plugged and reconstructed to ensure effective plugging. An old well of the Ye County gas storage in Henan Province was taken as an example,and the well section to be milled and plugged was determined according to the formation lithology and well diameter. A three-dimensional finite element model of the cement plug-formation system based on Cohesive elements was built for the milling-plugging old well section,the peeling failure laws of the cement plug-formation interface under the constant-pressure condition were clarified,and the limit peeling length of the interface was computed. The results show that for old wells without perforated sections,it is necessary to set cement plug barriers in the cap rock and salt sections,respectively,to prevent natural gas leakage in the vertical and lateral directions. Under the gas storage condition with a constant pressure of 20 MPa,the bottom of the cement plug presents slight deformation after being compressed,resulting in the shear deformation of the cement plug-formation bonding interface,and peeling occurs,as such deformation accumulates to a certain extent. With the increasing simulation time,the length of the peeling interface gradually increases and approaches the equilibrium,and the ultimate peeling failure length is 18.4 m. Moreover,the peeling length decreases with the growing elastic modulus of the cement plug. It is recommended to use the high-elastic-modulus cement slurry system for well plugging. The findings of this research help to decide whether the milled-plugged section length of the old well in the field is sufficient,and provide theoretical guidance for ensuring the long-term safe operation of the gas storage.

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    Settling Plugging Technology for Severe Lost Circulation at the Salt Bottom of Tarim Piedmont Zone

    LIU Fengbao, YIN Da, WEI Tianxing, WU Hongyu, WANG Ziwu
    Xinjiang Oil & Gas    2024, 20 (4): 1-7.   DOI: 10.12388/j.issn.1673-2677.2024.04.001
    Abstract78)      PDF (990KB)(53)       Save

    High-pressure gypsum salt beds and low-pressure clastic rock target beds are commonly developed in the piedmont zone of Tarim Basin,and the pressure difference between these two stratigraphic systems generally exceeds 20 MPa. Because of the inaccuracy of geological stratigraphic determination during drilling,it is highly likely to drill through the gypsum salt bed into the target bed and then trigger severe lost circulation. To solve the problem of severe lost circulation at the salt bottom of Tarim piedmont zone,this paper evaluates the performance parameters of plugging materials such as pressure-bearing capacity and settling velocity,identifies the optimal conditions (velocity and mass) of oil- and water- based drilling fluid (OBM and WBM) settling plugging pills respectively,and finally develops the high density large pressure difference settling plugging technology specialized for OBM and WBM,based on the known mechanism of the severe lost circulation problem (drilling induced communication between high and low pressure formations) and the principle of the "bottle plug" plugging practice. Specifically,optimal plugging pills are expected to form in the case of OBM with a oil-water ratio of 50:50 and ES of 200-300 V or WBM with 0.2% XC + 0.2% demulsifier + plugging agents. The developed settling plugging technology has been successfully tested in three wells in Tarim piedmont zone,and Well DB1302 was found with a pressure bearing capacity of 30 MPa,demonstrating excellent application performance.

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