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Research Progress on the Mechanisms and Control Methods of Casing Deformation in Shale Gas Horizontal Wells#br# YIN Aobo , LI Jun, , LIAN Wei , ZHANG Hui Xinjiang Oil & Gas    2025, 21 (1): 50-60.   DOI: 10.12388/j.issn.1673-2677.2025.01.006 Abstract （33）      PDF （3254KB）（131）       Knowledge map    Save Significant casing deformation （CD） occurs during multi-stage fracturing of shale gas horizontal wells，which reduces the ratio of recovered reservoirs and increases operation costs. Based on a comprehensive review of global research on this issue，a comparative analysis of the current status of casing deformation in shale gas horizontal wells was conducted. With the casing deformation data from Changning-Weiyuan，Luzhou，and Weirong blocks，the distribution patterns of casing deformation in terms of time，space，and morphology were summarized. The influences of engineering factors such as casing and cement sheath types，cementing quality，fracturing and perforation parameters，and thermal stresses，as well as geological factors such as reservoir heterogeneity and reservoir slip，on casing deformation，were analyzed. The analysis results indicate that while engineering factors can increase casing stresses，they are unlikely to cause casing deformation. Among geological factors，reservoir slip induced by natural fractures and faults activated during multi-stage fracturing is the main controlling factor leading to significant casing deformation. To address this issue，various control methods were summarized，including optimizing casing and cement sheath parameters，improving cementing quality，selecting appropriate fracturing and perforation parameters，optimizing wellbore trajectory，and controlling reservoir slip. Additionally，it was proposed to enhance the understanding of formations and improve prediction accuracy of reservoir slip. The research findings provide references for casing integrity design and control during the fracturing process. Reference | Related Articles | Metrics

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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 Abstract （119）      PDF （790KB）（86）       Knowledge map    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. Reference | Related Articles | Metrics

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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 Abstract （191）      PDF （2045KB）（79）       Knowledge map    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. Reference | Related Articles | Metrics

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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 Abstract （109）      PDF （5659KB）（68）       Knowledge map    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.  Reference | Related Articles | Metrics

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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 Abstract （128）      PDF （2630KB）（64）       Knowledge map    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. Reference | Related Articles | Metrics

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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 Abstract （97）      PDF （2526KB）（61）       Knowledge map    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. Reference | Related Articles | Metrics

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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 Abstract （78）      PDF （990KB）（53）       Knowledge map    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. Reference | Related Articles | Metrics

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Xinjiang Oil & Gas    2025, 21 (1): 0-.   Abstract （123）      PDF （13664KB）（51）       Knowledge map    Save Related Articles | Metrics

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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 Abstract （96）      PDF （1203KB）（50）       Knowledge map    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. Reference | Related Articles | Metrics

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Xinjiang Oil & Gas    2024, 20 (4): 0-0.   Abstract （38）      PDF （13678KB）（47）       Knowledge map    Save Related Articles | Metrics

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Application and Prospect of LiDAR Technology in Seismic Acquisition of Complex Mountainous Areas#br# XU Wenrui , WANG Liye , WEI Chencheng , QIN Xin , LIU Yiyan , PENG Xiao Xinjiang Oil & Gas    2025, 21 (1): 1-9.   DOI: 10.12388/j.issn.1673-2677.2025.01.001 Abstract （55）      PDF （12113KB）（44）       Knowledge map    Save The southern piedmont belt of Junggar Basin is rich in oil and gas resources. However，seismic exploration is faced with such problems as high implementation difficulties，low efficiency，high risks and high costs of field acquisition，due to the highly undulating surface conditions and complex underground structures. Therefore，the LiDAR technology was introduced to improve quality and efficiency in seismic acquisition. The functions of mountain excitation type division，mountain shot point pre-design，fine surface survey design，mountain vehicle navigation design and risk classification can be rapidly completed through the "far-looking" functionality of LiDAR images and high precision elevation data. With the application of this technology in mountain seismic acquisition，vibroseis has access into mountains，which effectively improves the excitation ratio of vibroseis in mountainous areas and the efficiency of field acquisition operations to improve quality and efficiency in the field. Looking ahead，it is believed that the LiDAR technology will play a greater role in seismic acquisition operations in complex mountainous areas. The high precision coordinates and elevation models of LiDAR images are expected to replace traditional measurement processes in field acquisition. The high resolution coordinates and elevations can improve the accuracy of surface modeling inversion. Rapid construction of digital outcrop models can be delivered with high definition imaging and digital elevation platforms. This technology promotes the upgrading of seismic exploration processes，the implementation of efficient exploration in mountainous areas，and data improvement for complex moutainous structures. Reference | Related Articles | Metrics

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Calculation of Casing Collapse Strength under Zipper Fracturing in Platform Wells LI Jun, , ZHANG Xiaojun , LIAN Wei , ZHANG Juncheng , LIU Gonghui Xinjiang Oil & Gas    2024, 20 (3): 37-45.   DOI: 10.12388/j.issn.1673-2677.2024.03.005 Abstract （69）      PDF （4873KB）（42）       Knowledge map    Save With the extensive applications of new technologies such as zipper fracturing in shale oil and gas development，the casing is subjected to both the multi-stage cyclic internal pressure and the external non-uniform compressive load caused by zipper fracturing operations. Given this，this paper analyzes the variation law of casing collpase strength under multi-stage cyclic load and zipper fracturing of platform wells via the multi-stage cyclic load experiments and numerical simulations. The calculation method of the casing comprehensive collapse strength coefficient under multi-stage fracturing is developed and applied to a casing-deformed well in  Xinjiang Oilfield. The results show that the casing collapse strength decreases linearly with the number of load cycles under cyclic loading. Zipper fracturing results in the non-uniform stress distribution around the well，and the casing collapse strength nearly linearly decreases with the increasing stress non-uniformity. Under the combined effects of internal and external loads，the casing collapse strength drops by more than 15%，which increases risks of casing deformation. The calculation method of casing callopase strength in platform wells proposed in this paper provides calculation guidance for the prevention of casing deformation in fracturing practice. Reference | Related Articles | Metrics

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Research on CO2 Matrix Penetration Distance in Tight Reservoirs MOU Jianye , YAN Xiaolun , ZHANG Shicheng , SHI Lei , LI Dong , MA Xinfang Xinjiang Oil & Gas    2024, 20 (3): 64-71.   DOI: 10.12388/j.issn.1673-2677.2024.03.008 Abstract （63）      PDF （2240KB）（39）       Knowledge map    Save During depletion recovery of tight oil，the reservoir pressure and production rate decline rapidly. Energy supplement is a necessary measure to enhance oil recovery. CO2 is a common medium used for energy replenishment （CO2 huff and puff，energy recharging by CO2 prepad）. The performance of CO2-assisted enhanced oil recovery （EOR） is highly dependent on the penetration distance. Therefore，the penetration distance of CO2 through the matrix of tight reservoirs was investigated via laboratory experiments and numerical simulation. Mass transfer of CO2 involves both convection and diffusion. Firstly，CO2 diffusion experiments were performed using a high-temperature high-pressure reactor and the cores of a tight formation. Based on the experimental results and Fick's diffusion model，the diffusion coefficient of CO2 was obtained. Next，CMG was used to build a model of CO2 convection and diffusion，and extensive numerical simulations were performed to analyze permeability，considering the effect of diffusion and flooding duration on CO2 penetration distance. The results show that the diffusion coefficient is dependent on permeability. The diffusion coefficient ranges from 10-10 to 10-8 m2/s at the permeability level of the target formation. Diffusion and convention both affect the CO2 penetration distance. Yet，the effects of convection are dominant with higher permeability，while those of diffusion are stronger with lower permeability. Permeability is a decisive factor of the matrix penetration of CO2. The CO2 penetration in tight reservoir matrix is rather low and reaches less than 10 m after 60 days. Reference | Related Articles | Metrics

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Research and Application Status of Plugging Materials for Drilling Fluid QIAO Mu, , ZHU Zhongxi, , YAN Kangkai, Xinjiang Oil & Gas    2025, 21 (1): 10-23.   DOI: 10.12388/j.issn.1673-2677.2025.01.002 Abstract （37）      PDF （5410KB）（39）       Knowledge map    Save Lost circulation is a common and challenging downhole complex issue in current drilling operations. It has become one of the major factors affecting drilling speed and may lead to safety incidents of different levels. By comprehensively analyzing the types and mechanisms of lost circulation，the performances of global novel plugging materials under different operating conditions，and their interactions with factors such as the wellbore and formations，this study elucidates the characteristics and mechanisms of cement，cross-linking system and metallic plugging materials，granular and fiber lost circulation materials （LCMs），and the combination of curable materials and LCMs. The application performances and pros and cons of different types of LCMs for lost circulation in various formations are summarized. The results indicate that given both the treatment success rate and cost-effectiveness，cement plugging materials are preferred for handling fluid loss caused by the highly permeable rock matrix，with a treatment success rate of 91%. To address the karst-cavern thief zone，curable materials with LCMs are relatively favored，delivering a treatment success rate of 89%. Fiber LCMs are preferred for treating natural fracture-type lost circulation，with a treatment success rate of 75%. When dealing with the induced fracture-type lost circulation，granular LCMs are favorable，with a treatment success rate of 92%. The findings of this research are of important theoretical and technical guiding significance for enhancing the plugging performance of drilling fluids and promoting the development of lost circulation plugging technology. Reference | Related Articles | Metrics

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Quantitative Evaluation of Frac Hits Based on Shut-in Pressure Drop Curve：Taking Shale Oil Platform Wells in Jimsar as an Example WANG Fei, DONG Zhuo, XU Tianlu, CHEN Lu, WANG Zhengkai, LI Zhanjie Xinjiang Oil & Gas    2024, 20 (3): 91-98.   DOI: 10.12388/j.issn.1673-2677.2024.03.011 Abstract （60）      PDF （3284KB）（38）       Knowledge map    Save Given the lack of quantitative evaluation methods for frac hits effects，a diagnostic analysis method was developed based on  shut-in pressure drop curve. For the zipper fracturing process of a platform well group，the shut-in pressure drop curves under four typical frac hits modes were identified and used to diagnose frac hits types. Six typical fracturing stages with frac hits of the Jimsar platform A were selected as application cases of the proposed method. The method effectiveness was verified by comparing the application results with the microseismic monitoring results. Moreover，based on the pressure drop well testing interpretation method，the typical shut-in pressure drop curves of two frac hits types in Jimsar，namely the internal frac hits within a new well group，and the  frac hits between new and old well groups，were fitted and analyzed to interpret fracture network parameters. The interpretation results showe that the internal frac hits within a new well group affects the stimulation effects of both the primary and secondary fractures，and the specific hit effects vary with the frac hits types. The frac hits between new and old well groups mainly affects the stimulation effect of primary fractures，resulting in the change of fracture networks from "long and wide" to "short and narrow". Correspondingly，the effective fracture volume is reduced by 28%，and the overall stimulation effect is degraded. Related Articles | Metrics

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Intelligent Optimization of Integral Fracturing in Unconventional Reservoirs ZHANG Li , WANG Bo , LYU Zhenhu , LYU Bei , LI Lizhe , ZHOU Hang Xinjiang Oil & Gas    2024, 20 (4): 36-43.   DOI: 10.12388/j.issn.1673-2677.2024.04.005 Abstract （41）      PDF （3096KB）（37）       Knowledge map    Save Integral fracturing is one of the key technologies for the cost-effective development of unconventional reservoirs，which delivers one-time well placement，one-time fracture placement and synchronized initiation of production through batch drilling and batch fracturing. Optimization of well and fracture spacing is of great significance to improve the performance of integral reservoir stimulation. In this work，a typical block of the Mahu conglomerate reservoir is taken as an example to establish a three-dimensional geological model through the geology-engineering-integrated Petrel platform using well logs，mud logs and fracturing treatment parameters. Based on CMG，a numerical reservoir simulator，and logarithmic mesh refinement method，a hydraulic fracturing model of a four-well platform is constructed for production forecasting. Using the particle swarm optimization （PSO） and differential evolution （DE） algorithms，the well spacing and the fracture spacing of the four-well platform are optimized with the well group productivity as the objective function，which realizes the seven-dimensional synchronized parameter optimization. The optimized well group productivity is about 16.3% higher than that of the actual case. The optimized four-well platform presents a longer stable production duration and slower production decline. The optimized hydraulic fracturing treatment is found with a larger affected zone，further promoting the improvement of oil productivity. The findings of this work provide the fundamental model and methodology for optimizing the integral fracturing scheme of unconventional reservoirs. Reference | Related Articles | Metrics

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The Diffusion Law of Salt Ions in Shale Reservoirs and Its Application in Hydraulic Fracture Network Diagnostics#br# LIU Zhenjun , ZHANG Yanjun , LIAO Wanrong , YANG Bing , YANG Liu , ZHOU Desheng Xinjiang Oil & Gas    2025, 21 (1): 41-49.   DOI: 10.12388/j.issn.1673-2677.2025.01.005 Abstract （23）      PDF （1516KB）（37）       Knowledge map    Save Shale reservoirs are characterized by low porosity，low permeability，and difficulty in exploitation，typically requiring the development approach combining long horizontal wells with large-scale volume fracturing techniques. After the fracturing fluid enters the formation，it undergoes a series of physical and chemical reactions with the reservoir，where salt ion diffusion plays a significant role. However，the existing research on the mechanism of ion diffusion and its application to diagnosing hydraulic fracture network is still imperfect. Therefore，this paper combines theoretical analysis with field cases to summarize the sources of salt ions in shale reservoirs，and the characteristics，mechanisms and influencing factors of ion diffusion，and presents an example of diagnosing hydraulic fracture network based on salt ion diffusion. The sources of salt ions in shale reservoirs include dissolved salts in the water film on the pore walls，crystallized salts from hydrocarbon generation and water expulsion，and salts produced by water-rock interactions. The characteristics of ion diffusion are similar to the imbibition process，which is divided into three stages：initial，transitional，and late diffusion. The initial ion diffusion rate is relatively high，exhibits a linear relationship on a logarithmic time scale，and follows Fick's law and the Einstein-Smoluchowski equation. The factors affecting salt ion diffusion include reservoir properties，solution properties，and other factors such as temperature and viscosity. Saltion diffusion can be used for the diagnosis of the development degree of volume fracturing fracture network. The method of diagnosing hydraulic fracture network through salt ion diffusion can provide scientific guidance for shale reservoir fracturing design and fracture network evaluation，help to deliver more accurate and effective reservoir stimulation and promote the efficient development and utilization of shale oil and gas resources. Reference | Related Articles | Metrics

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EOR Scheme Optimization of CO2 Miscible Flooding in Bohai BZ Reservoir WU Zheng, LING Haochuan, WANG Jijun, ZHAO Zhuo, LI Shan Xinjiang Oil & Gas    2024, 20 (4): 70-76.   DOI: 10.12388/j.issn.1673-2677.2024.04.009 Abstract （45）      PDF （1717KB）（36）       Knowledge map    Save For the first time，CO2 flooding is attemptively applied to the BZ low permeability reservoir of Bohai Sea area. To capture the rule of CO2 miscible flooding in the target reservoir，the minimum miscibility pressure （MMP） and displacement efficiency of the target block were determined using two methods，namely the slim tube and long core flooding tests. The results show that the MMP measured via the slim tube test is 32.65 MPa，and miscibility can be realized in the field. The long core flooding incorporates the actual characteristics of the reservoir，and the measured displacement efficiency is more consistent with the field development reality. The conceptual model was built by numerical simulation to analyze the effects of the injector-producer spacing and injection intensity on the sweep efficiency of gas injection. It is shown that during the early development with the high reservoir pressure，injected gas mainly migrates along the high permeability reservoir；it sweeps the medium-low permeability reservoir，as the reservoir pressure declines and the gravity segregation of CO2，induced by the oil-gas density difference，intensifies. For reservoirs with relatively inferior porosity and permeability，production wells shall be stimulated （e.g. fracturing） to improve the injector-producer pressure difference and ensure sufficient production. In accordance with the development indexes，an injector-producer spacing within 350-400 m and injection intensity of 1×104-2×104 m3/d are preferred. For the optimized scheme，the recovery rate is predicted to be 2.7%/a，associated with an estimated recovery factor of 22.2% and cumulative CO2 storage of 107×104 t. The findings of this research provide technical support for the gas flooding scheme and well location/spacing determination and are of great practical significance for offshore gas flooding. Reference | Related Articles | Metrics

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Faults at Various Scales Identification Techniques in Shale Reservoirs LI Ang, WU Ningyu, ZHANG Liyan, YIN Wen Xinjiang Oil & Gas    2024, 20 (3): 30-36.   DOI: 10.12388/j.issn.1673-2677.2024.03.004 Abstract （72）      PDF （4140KB）（36）       Knowledge map    Save Qingshankou Formation of the southern Qijia Sag in Songliao Basin develops shale reservoirs，and shale oil is becoming an important replacement field for increasing reserves and production of hydrocarbons in this area. Qingshankou Formation has been cut by different sets of faults during its deposition，and the difficulty in fault identification and fracture prediction has affected the understanding of the main control factors of the reservoir in this area. It is of great significance to accurately identify the distribution characteristics of faults of different levels for shale oil exploration in this area. Seismic attribute analysis is one of the effective means of fault identification and reservoir prediction. Different seismic attributes can describe different geological characteristics，and it is hard to use a single seismic attribute to comprehensively and accurately identify faults. In this paper，the variance cube attribute，3D structural curvature attribute，structural smoothing and 3D edge enhancement technique，ant body attribute as well as other seismic multi-attribute fault identification techniques are comprehensively used to improve the identification accuracy of faults of different levels，and a set of shale formation fault identification technical process is formed which is effective for faults of different levels and scales. The characteristics of fault distribution in the study area are effectively described，and the planar distribution prediction of faults of different levels is realized. This research overcomes the limitations of the single seismic attribute method in fault identification and prediction，and provides a reliable basis for the deployment of oil and gas exploration. Reference | Related Articles | Metrics

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NMR-Based Experiments of Fracturing Fluid Assisted CO2 Huff-n-Puff for Enhancing Shale Oil Recovery XIAO Wenlian, CHEN Shengen, YI Yonggang, CHEN Haoyu, REN Jitian Xinjiang Oil & Gas    2024, 20 (3): 83-90.   DOI: 10.12388/j.issn.1673-2677.2024.03.010 Abstract （69）      PDF （4361KB）（36）       Knowledge map    Save To develop a huff-n-puff development mode of shale oil facilitating continuous reservoir energy supplement，the integrated simulation experiment of CO2 huff-n-puff assisted by fracturing fluids for Jimsar shale oil reservoir was completed using low frequency nuclear magnetic resonance （NMR） core analyzer. The characteristics of pore throat fluid production and recovery rate variation of the core during the composite development of multi-medium cyclic injection and flooding were investigated to evaluate the enhanced oil recovery （EOR） performance of the fracturing fluid-assisted CO2 huff-n-puff. Finally，the novel development mode of huff-n-puff energy supplement was proposed for shale oil. The experimental results showed that in the case of conventional CO2 huff-n-puff，the recovery rate of core samples decreases rapidly from cycle to cycle，and only the oil in medium and large pores is produced. The oil production is mainly contributed by the first two cycles，and the ultimate recovery factor is 30%~40%. For the CO2 huff-n-puff assisted by fracturing fluids，in which the CO2 injection end was used for production，the produced oil is also mostly limited to medium and large pores. The oil production is mainly attributed to the first three cycles，and the ultimate recovery factor is 30%~40%. In terms of the CO2 huff-n-puff assisted by fracturing fluids，with the fracturing fluid injection end used for production，the oil in all pores is produced，and the ultimate recovery factor is 70%~80%. This mode leaves evenly distributed remaining oil and the highest development performance. The findings of this research provide a theoretical basis for the field practice of shale oil EOR based on huff-n-puff reservoir energy supplement. Reference | Related Articles | Metrics

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Analysis of BHA Build-Up Performance for Jimsar Shale Oil Horizontal Wells ZHAO Yanlong , FAN Xu , CHU Haoyuan , LI Xuanxuan , YUAN Yalong , ZHENG Tianhui Xinjiang Oil & Gas    2024, 20 (4): 19-24.   DOI: 10.12388/j.issn.1673-2677.2024.04.003 Abstract （41）      PDF （996KB）（35）       Knowledge map    Save Well trajectory control is a key task in drilling horizontal wells. The purpose of this study is to determine the influences of BHA （bottomhole assembly） parameters on build-up capacity of horizontal wells in Jimsar shale oil. The build-up efficiencies of conventional and rotary steering tools of nine horizontal wells in this block are compared and analyzed. The mechanical properties of different BHAs and the influence laws of different factors on the build-up capacity of drill assembly are investigated via the beam column approach，and suggestions are given for PDM （positive displacement motor） drill parameters. Research shows that from high to low，the build-up capacity in the case of the drill assembly parameters in this block ranks as listed：single bend PDM drill assembly with single stabilizer （sliding drilling），rotary steering tools，single bend PDM drill assembly with double stabilizer （sliding drilling），and finally single bend PDM drill assembly with double stabilizer （compound drilling）. For PDM drill，the following measures can be taken to increase the build-up capacity：increasing bend angle，spacing of stabilizers and first stabilizer size；decreasing the second stabilizer size. The findings of this research provide guidance for the selection of build-up tools for Jimsar shale oil horizontal wells. Reference | Related Articles | Metrics

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Performance and Displacement Effect Evaluation of Multifunctional Fracturing-Enhanced Oil Recovery Materials GUO Jixiang, ZHANG Xiaojun, CHU Yanjie, ZHAO Kun, PENG Zhongying Xinjiang Oil & Gas    2024, 20 (3): 72-82.   DOI: 10.12388/j.issn.1673-2677.2024.03.009 Abstract （57）      PDF （6351KB）（35）       Knowledge map    Save Poor pore-permeability，high shale oil viscosity，strong reservoir-wellbore flow risk，low primary recovery and single unsuitable slickwater fracturing fluids are the problems facing the development of Jimusar shale oil. SDY-1+XC-4，a multifunctional slickwater fracturing fluid system，was developed based on SDY-1，a multifunctional fracturing-enhanced oil recovery (EOR) material for viscosity reduction，oil washing，and imbibition. The performances of temperature and shear resistant，viscosity reduction，oil washing and imbibition were evaluated through laboratory experiments. Its applicability under reservoir temperature and salinity was analyzed. And the slickwater system has been applied in Jimsar. Results showed that SDY-1 has high compatibility with XC-4. SDY-1+XC-4 exhibits good temperature and shear resistance at reservoir temperature. At 30 ℃，the viscosity reduction rate of SDY-1+XC-4 is 93.68%，the oil washing efficiency is 66.7%，and the imbibition recovery rate is 33.24%. SDY-1+XC-4 works well under the reservoir temperature and salinity. The field testing results showed that the test well presents cumulative oil increase of 2 031.6 t，compared with the reference well. The development and application of the multifunctional fracturing-EOR materials can provide a solid foundation and technical support for the efficient development of Jimsar shale oil. Reference | Related Articles | Metrics

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Xinjiang Oil & Gas    2024, 20 (3): 0-.   Abstract （52）      PDF （12977KB）（31）       Knowledge map    Save Related Articles | Metrics

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Prediction Method and Prevention Measures for Casing Deformation of Horizontal Well in Volume Fracturing#br# .Oil Production Technology Research Institute, PetroChina Xinjiang Oilfield Company, Karamay , Xinjiang, China, .Downhole Operation Company, CNPC Western Drilling Engineering Co., Ltd., Karamay , Xinjiang, China Xinjiang Oil & Gas    2025, 21 (1): 61-68.   DOI: 10.12388/j.issn.1673-2677.2025.01.007 Abstract （27）      PDF （5095KB）（30）       Knowledge map    Save Horizontal well volume fracturing has become a key technology for well completion and reservoir stimulation of tight oil reservoirs. For reservoirs with well-developed natural fractures and faults，high-intensity reservoir stimulation greatly increases the probability of artificial fracture-induced fault sliding，leading to casing deformation. To avoid hydraulic fracturing-induced fault sliding which could lead to shear deformation of casing，numerical simulation was used as a means to study the prediction method and prevention measures of casing deformation risk points. The H well group was taken as a field example in this research，and based on the integrated geological-engineering model and ant body tracking technology，the risk points of casing deformation were determined. With Mohr-Coulomb criterion and fracturing parameter optimization，the risk points of casing deformation were efficiently controlled，with effective preventive measures. The research results indicate that the integrated geological-engineering model and ant body tracking technology can effectively identify faults and natural fractures intersected by the well trajectories，and 20 risk points of casing deformation are predicted for the H well group. The threshold of fault activation sliding pressure was determined to be 70 MPa as per the Mohr-Coulomb criterion. The volume fracturing treatment of the H well group was carried out in a way following the strategy of "unaligned perforation + reduced pump rates + reduced injected water volumes"，and no casing deformation occurred during the fracturing operation process. A risk point prediction and prevention technology for casing deformation has been developed，effectively ensuring the safety of horizontal well volume fracturing opertation and improving the efficiency of reservoir stimulation，and providing technical references for the research on casing deformation prediction and prevention measures. Reference | Related Articles | Metrics

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Oil-Based Drilling Fluid Anti-Collapse Technology for Long Openhole Wellbore of Jimsar Shale Oil#br# WU Yicheng, LIU Peng, CAO Qingtian, CHANG Huipan, LI Shuai, ZHANG Bin Xinjiang Oil & Gas    2025, 21 (1): 32-40.   DOI: 10.12388/j.issn.1673-2677.2025.01.004 Abstract （34）      PDF （5446KB）（29）       Knowledge map    Save The horizontal well of Jimsar shale oil with a long openhole wellbore adopts the two-casing-section structure，and the openhole wellbore of the second casing section is 4 000 m long，with a horizontal wellbore over 2 000 m. The used drilling fluids are oil-based，and wellbore collapse tends to occur when drilling the Badaowan and Jiucaiyuanzi Formations and leads to movement resistance，sticking of tools，lost circulation，etc. To overcome the wellbore collapse in complex formations，in accordance with the lithological characteristics of formations，the main factors affecting wellbore stability such as clay mineral composition and micro-fracture development were analyzed，the mechanisms of wellbore instability of such collapse-prone formations were clarified，and the anti-collapse theory of oil-based drilling fluids was developed，which features "multi-element cooperation and broad-spectrum plugging". Based on the proposed theory，the anti-collapse formulation of oil-based drilling fluids was improved by optimizing the materials such as asphalt products，ultra-fine calcium carbonates and nano-plugging agents. The laboratory tests show that the performance parameters of the drilling fluids meet the operation requirements and the plugging performance is excellent. Specifically，the drilling fluid density is 1.52-1.62 g/cm3；funnel viscosity，80-100 s；yield point，8-13 Pa；emulsion-breaking voltage，above 500 V；oil-water ratio，（80：20） to （85：15）；API fluid loss，≤ 1.5 mL；HTHP fluid loss at 120°C，≤ 2 mL. The presented anti-collapse system of oil-based drilling fluids has been successfully applied to Jimsar shale oil horizontal wells with a long openhole wellbore. The average borehole enlargement rate of the openhole wellbore and the rate of downhole complex issues were 3.03% and 0.55% respectively. The anti-collapse system effectively ensured the drilling safety of the build-up and horizontal wellbores. Reference | Related Articles | Metrics

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CO2 Corrosion Resistance Evaluation of Packer Rubber in CCUS Wells WANG Sui , SONG Shaohua, , CHEN Sen , ZHANG Liyi , CHEN Zhijun , LI Yanpeng, Xinjiang Oil & Gas    2024, 20 (4): 50-59.   DOI: 10.12388/j.issn.1673-2677.2024.04.007 Abstract （71）      PDF （8242KB）（29）       Knowledge map    Save Packers are important tools for CCUS flooding operations，and the reliability of packer rubber directly affects the packer performance. In order to explore the corrosion resistance of packer rubber in a critical CO2 environment，the corrosion resistance and mechanical properties of nitrile rubber （NBR），hydrogenated nitrile rubber （HNBR） and fluororubber （FKM） in a simulated supercritical CO2 environment were studied. The high temperature high pressure corrosion tests show that the largest mass increment after tests is observed in the NBR rubber （6.81%） and the least one in the HNBR rubber （2.48%）. The NBR rubber is also found with the largest outside diameter （OD） increment （4.21%），and the HNBR with the smallest OD increment. The largest and lowest drops of tensile strength occur in the FKM and HNBR materials，respectively （66.85% and 37.78%）. The results show that with the increasing service time and ambient temperature，the rate of corrosive media like CO2 entering rubber is accelerated，which aggravates the damage of the rubber crosslinking network and degrades the mechanical properties. Because weak bonds like unsaturated double bonds in HNBR are fewer than those in NBR，and the bond energy of HNBR is higher than that of the N-O bond of FKM，the stability of HNBR in supercritical CO2 is better than those of the other two. Therefore，HNBR is recommended to be used as sealing elements of packers in CO2 flooding injection wells. Reference | Related Articles | Metrics

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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 Abstract （82）      PDF （662KB）（28）       Knowledge map    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. Reference | Related Articles | Metrics

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Research on Oil Stabilization and Water Control Performance of Relative Permeability Regulator Grafted Proppant#br# ZHANG Wei, , WEN Xuejun , PU Di , LUO Pingya , GUO Yongjun, , XIONG Qiyong Xinjiang Oil & Gas    2025, 21 (1): 69-77.   DOI: 10.12388/j.issn.1673-2677.2025.01.008 Abstract （30）      PDF （1987KB）（26）       Knowledge map    Save In a certain area of Karamay Oilfield，numerous production wells suffer from rapid water cut rise and high water cut after fracturing treatments. To solve this problem，the proppant grafted with the hydrophobic association relative permeability regulator，RPM-SiO2，was developed by grafting the hydrophobic association relative permeability regulator onto the quartz sand surface，with the help of silane coupling agents KH570. The grafting of relative permeability regulators onto the proppant surface was confirmed successful by infrared spectroscopy and electron scanning microscopy （SEM）. Under the reservoir conditions of the study area of Karamay Oilfield，the differences of conventional performance （wettability，density，acid solubility and compressive strength），fracture conductivity，and water control ability between RPM-SiO2 and blank quartz sand proppants were investigated. The results show that the comprehensive performances of RPM-SiO2 and quartz sands are basically consistent，both meeting the requirements of the industrial standard. The resultant oil phase fracture conductivities are consistent，but the water phase fracture conductivity of RPM-SiO2 is 25% lower than that of quartz sands. Compared with quartz sands，RPM-SiO2 presents a decrease of 83.41% in the water phase permeability，17.49% in the oil phse permeability，and 18.65% in the water cut of produced liquid. RPM-SiO2 has high water control capability and long-term effectiveness. Reference | Related Articles | Metrics

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Hydraulic Filtrate Waste Recycling Technology for Water-Based Drilling Fluids in Longdong Oil Block#br# SHAO Bin , LUO Pingya, , LAN Jun , LIU Lu, , CHANG Junli , YANG Zhen, Xinjiang Oil & Gas    2025, 21 (1): 24-31.   DOI: 10.12388/j.issn.1673-2677.2025.01.003 Abstract （32）      PDF （2158KB）（25）       Knowledge map    Save Longdong Oil Block requires the full implementation of drilling fluid non-landing technology to promote the recycling of waste drilling fluid. In order to solve the problem that the performance of water-based drilling fluids prepared using on-site hydraulic filtrate waste cannot meet the standards and the influencing factors are not clear，the ethylene diamine tetraacetic acid（EDTA） titration，bacterial plate counting method and atomic absorption spectrometry （AAS） were used to investigate the key techniques to improve the reuse rate of hydraulic filtrate waste. The experiments show that the high content of calcium and magnesium ions，bacteria，and heavy metals are the main reasons for the poor performance of water-based drilling fluids prepared using hydraulic filtrate waste. Correspondingly，the modified coagulation and precipitation complexing agent II，polyether demulsifier JX，and flocculants ZY-I，ZY-II have been developed to perform the flocculation-precipitation-sterilization treatment together with the sterilizing agent. The resultant average removal rate of calcium and magnesium ions is 95.5%，the sterilization rates of saprophytic bacteria （TGB） and sulfate-reducing bacteria （SRB） are 96.54% and 100% respectively，and the heavy metal content is less than 2.31 μg/L. The laboratory tests of recycling of hydraulic filtrate waste and water-based drilling fluid preparation have been completed for 6 wells in Longdong Oil Block. Longdong Oil Block waste drilling fluid hydraulic filtrate recycling technology has been formed and applied in 5 wells of this block. The water-based drilling fluids prepared using the recycled hydraulic filtrate waste presents a performance in line with the drilling engineering design requirements，facilitating the smooth drilling process，effectively protecting the environment and saved water resources，demonstrating good prospects for application promotion. Reference | Related Articles | Metrics

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Research Progress on Mechanical Composite Piping Technology for Oil and Gas Field Gathering and Transportation#br# ZENG Dezhi , SHI Shengyao , LI Yiyang , SUN Jianghe , SU Rigu , CHEN Siyu Xinjiang Oil & Gas    2025, 21 (1): 87-94.   DOI: 10.12388/j.issn.1673-2677.2025.01.010 Abstract （23）      PDF （1040KB）（23）       Knowledge map    Save Bimetallic composite piping technology is an important method to solve the internal corrosion of pipelines of the gathering and transportation system of oil and gas fields. The forming，welding and testing are the prerequisites for safe pipeline operations. To ensure the safe production of oil and gas fields，the progress of the forming，welding and non-destructive testing （NDT） technologies of bimetallic mechanical composite piping was reviewed. Two commonly used mechanical molding methods and their characteristics were clarified，the process methods for improving the quality of welded joints were analyzed，and the NDT technologies for different pipeline defects were summarized. The results show that in terms of pipe forming，explosive forming and hydraulic forming are commonly used in China for composite piping，but they still have limitations in manufacturing large-diameter pipes and special-shaped pipe fittings；in terms of welding，the quality of welded joints can be improved by optimizing the welding process，and the laser cladding technology of pipe ends has become a future research direction；in terms of the NDT，traditional testing methods are gradually developing towards intelligent and integrated modern technologies，delivering a wider coverage and higher defect detection rates. In addition，if the pipe end measurements at key steps of the full life cycle of mechanical composite piping are recorded，accurate traceability can be achieved once quality problems occur. It is concluded that improving the quality control of mechanical composite piping technology during the forming and welding processes and the accuracy of the NDT technologies is of great significance for their applications in oil and gas field gathering and transportation. Reference | Related Articles | Metrics

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Experimental Study on Etched Fracture Conductivity in Carbonate Rocks for Supercritical CO2 Prepad Acid Fracturing#br# ZHONG Pengjun , LIU Chao , WEI Chengxiang , ZHOU Weiqin , TIAN Shouceng , WU Jinqiao Xinjiang Oil & Gas    2024, 20 (4): 60-69.   DOI: 10.12388/j.issn.1673-2677.2024.04.008 Abstract （52）      PDF （3371KB）（21）       Knowledge map    Save Previously，the carbonate reservoir of Majiagou Formation in Yan'an Gas Field adopted traditional acid fracturing treatments，which ended up with a limited acid-affected range and low post-frac well production. This necessitates the optimization of the acid fracturing practice. The reservoir outcrop samples of the Fifth Member of Majiagou Formation were collected for experiments，and the etched-fracture conductivity meter and 3D laser scanning technology were used for acid etching experiments and fracture conductivity measurement in the cases of supercritical CO2 （SC-CO2） prepad acid fracturing and conventional acid fracturing. The effects of  prepad SC-CO2 and SC-CO2 soaking time on etched fracture morphology and conductivity were investigated. The results demonstrate that acid fracturing with prepad SC-CO2，compared with the conventional method，opens natural fractures，enhances the penetration and diffusion of acid solutions into micro-fractures，and thereby improves acidizing effectiveness. After 12 h and 24 h of SC-CO2 Soaking，the dominant acid etching pattern resembles grooves，with no significant changes in overall etching severity or types.The 48 h soaking ething is associated with the predominant bridge-pier-like etching marks，while the uniform etching is found dominant after 72 h soaking. The difference of fracture conductivity between conventional acid fracturing and SC-CO2 prepad acid fracturing is minor under the closure pressure below 30 MPa，and yet，a substantial disparity emerges beyond this threshold. The fracture conductivity of SC-CO2 prepad acid fracturing consistently exceeds that of conventional acid fracturing across the closure pressure range of the experiments. In cases of low closure pressure，the soaking duration is positively correlated with the etched fracture conductivity，whereas excessively prolonged soaking periods under high closure pressure can suppress fracture conductivity. Therefore，48 h well shut-in is recommended. The findings of this research provide theoretical support for the scheme development of compound acid fracturing in carbonate reservoirs. Reference | Related Articles | Metrics

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Development and Performance Evaluation of a High-Efficiency Asphalt Dispersant ZHENG Cunchuan , WANG Wei , CHEN Shengen , WANG Rui , CHEN Jiangdong Xinjiang Oil & Gas    2025, 21 (1): 78-86.   DOI: 10.12388/j.issn.1673-2677.2025.01.009 Abstract （22）      PDF （3158KB）（19）       Knowledge map    Save In order to solve the problem of severe blockage caused by the gradual precipitation，aggregation and settlement of asphaltenes with the decreasing temperature during the artificial lifting process in Tahe Oilfield，a high-efficiency asphalt dispersant was developed and evaluated via the steel wire mesh dissolution method. Through the characterization analysis of the wellbore sediments by three-component solvent fractionation，elemental composition determination and scanning electron microscopy （SEM），asphaltenes were determined to be the main component of Tahe wellbore sediments. According to the principle of similar mutual solubility ，a dispersant LYH-1 （aromatic solvent LY + 1.0% n-pentanol + 1.0% nonylphenol + 0.2% petroleum sulfonate） that could efficiently dissolve asphaltenes was developed. The asphaltene sediments were soaked in the asphalt dispersant LYH-1 in a water bath at 50°C for 4 h，and the solubility of 1 g of asphaltene sediments in 5 g of asphalt dispersant LYH-1 was as high as 97%，and the sediments did not aggregate after long-term standing，suggesting excellent stability and expanded applicability. The investigation of the working mechanism of the high-efficiency asphalt dispersant LYH-1 demonstrates that the dispersant forms a stable system with asphaltene sediments，mainly through hydrogen bonding and π-π interaction，which reduces the particle sizes of asphaltene aggregates to allow them to be stably suspended in solutions，and hinders the further flocculation and deposition of asphaltenes. The results show that LYH-1，as a novel high-performance asphalt dispersant，can effectively prevent the blockage of oil wells and surface pipelines while reducing production costs，so as to achieve the goal of production growth and improve the development efficiency of heavy oil reservoirs. Reference | Related Articles | Metrics

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Temperature，Pressure and Phase Transition Characteristics of Supercritical CO2 Pipeline During Commissioning Replacement Process in Xinjiang Oilfield#br# LI Xinze, , WANG Dezhong , ZHANG Haifan , LIU Shuangquqn , ZHU Tao, , XING Xiaokai, Xinjiang Oil & Gas    2024, 20 (4): 77-86.   DOI: 10.12388/j.issn.1673-2677.2024.04.010 Abstract （59）      PDF （1552KB）（18）       Knowledge map    Save Due to the phase characteristics of CO2，the commissioning and replacement process of supercritical CO2 pipelines is significantly different from that of crude oil and natural gas pipelines. In this paper，OLGA software was used to simulate the commissioning and replacement process of the supercritical CO2 pipeline demonstration project in Xinjiang Oilfield，and the dynamics of pressure，temperature，density，phase transition and other parameters were captured. The effects of the initial back pressure，CO2 injection massive flow of various phases in first station filling and ambient temperature on the replacement time，temperature，pressure，phase transition process and CO2 consumption were investigated. Findings indicate that in the liquid CO2 injection stage，gaseous CO2 is constantly squeezed，and the thermal movement of gaseous CO2 molecules is intensified due to pressurization，leading to concurrent increases in pressure and temperature. Consequently，the fluids at the pipeline's end transitions directly from the gaseous to the supercritical phase. Enhancing the mass flow rate of CO2 injection in each phase can expedite the replacement process. To ensure the pipeline's maximum temperature keeping below 50 ℃，the injection flow rate of CO2 in the liquid phase should be capped at 0.5 m/s. The increase in ambient temperature significantly elevates the liquefaction pressure，prompting the fluids in most pipe sections to transition directly from the gaseous to supercritical phase，which is unfavorable for phase control. Therefore，commissioning during summer is not advisable. To facilitate the assessment of the production plan，three key indexes were proposed：safety index （pipeline temperature），efficiency index （time consumption of commissioning） and economic index （CO2 consumption），with the safety index taking precedence. The research results offer valuable insights for the development of production plans for supercritical CO2 pipelines. Reference | Related Articles | Metrics

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Evaluation Method for Storage Capacity Expansion and Design Production Realization of Underground Gas Storage in Gas Cap Reservoirs：A Case Study of J Gas Storage#br# XIAN Mengyuan , XI Zengqiang , WANG Xiuwei , JIA Shanpo , ZHANG Bo Xinjiang Oil & Gas    2024, 20 (4): 27-35.   DOI: 10.12388/j.issn.1673-2677.2024.04.004 Abstract （30）      PDF （807KB）（15）       Knowledge map    Save The evaluation method of storage capacity expansion and design production realization is key to achieving efficient underground gas storage （UGS） operation and predicting the future UGS state. In order to understand the operational rules of UGS storage capacity expansion and design production realization，this paper investigates the J gas storage，a UGS of gas cap reservoir as an example. Based on tracking the basic UGS production data and analyzing the development performance of the gas reservoir，this paper analyzes the multi-cycle injection and production operation data of the UGS and evaluates the pressure，storage capacity，gas production capacity of wells and injection-production operation performance of the UGS，using the dynamic evaluation technology of UGS in gas fields. The main factors affecting the storage capacity expansion and design production realization of the J gas storage are clarified. It is suggested that the J gas storage is transitioning from the capacity expansion stage to the stable stage，but the subsequent storage capacity expansion is challenging，because the drainage well fails to drain normally with gas channeling in the reservoir. It is necessary to perform fine reservoir description of the UGS to clarify the reservoir sand body distribution pattern and identify gas channels. Meanwhile，numerical simulation shall be done to develop a reasonable injection-production scheme to avoid impacts of gas channeling in drainage wells and resume storage capacity expansion. A method for evaluating the UGS capacity expansion and production realization has been developed，which provides technical support and references for the construction of similar UGS facilities and realization of UGS storage and production capacity targets. Key words：gas storage in gas cap reservoir；storage capacity；working gas volume；injection-production Reference | Related Articles | Metrics

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Applications and Prospect of DeepSeek Large Language Model in Petroleum Engineering TIAN Huiyang, LIU Ruiheng, LI Dongshuang, YOU Shaohua, LIAO Qinzhuo, TIAN Shouceng Xinjiang Oil & Gas    2025, 21 (2): 55-.   DOI: 10.12388/j.issn.1673-2677.2025.02.006 Abstract （30）      PDF （3419KB）（12）       Knowledge map    Save The emergence of large language models（LLM） with characteristics of general artificial intelligence has ushered in a milestone technological revolution across industries，offering new opportunities for the intelligent transformation of petroleum engineering. This paper explores the application prospect，challenges，and development recommendations for LLM，represented by DeepSeek，in petroleum engineering. First，the fundamental concepts and technical features of LLM are introduced. Subsequently，potential application scenarios in petroleum engineering are examined，including user interaction and Q&A systems，data governance and information integration，data analysis and decision support，information parsing and intelligent assistance，and environmental monitoring and safety management. Concurrently，limitations and challenges in applying LLM to petroleum engineering are identified，such as insufficient knowledge updating capabilities，difficulties in comprehending domain-specific expertise，limited innovation in scientific research，and high training costs. Finally，recommendations and future directions for leveraging LLM in petroleum engineering are proposed，including developing specialized LLMs tailored for petroleum engineering，constructing petroleum-domain databases and information extraction frameworks，integrating internet-enabled search and real-time updating functionalities，and advancing image processing and video generation technologies. This study systematically outlines an implementation framework for LLM in petroleum engineering，providing theoretical guidance and practical references for the industry’s intelligent evolution. Reference | Related Articles | Metrics

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Research Status and Prospect of Deep and Ultra-deep Drilling Technology SUN Jinsheng, , YANG Jingbin , LV Kaihe , BAI Yingrui , LIU Jingping , HUANG Xianbin Xinjiang Oil & Gas    2025, 21 (2): 1-14.   DOI: 10.12388/j.issn.1673-2677.2025.02.001 Abstract （26）      PDF （7345KB）（11）       Knowledge map    Save This paper systematically discusses the research progress of the deep and ultra-deep drilling technology in both China and other countries，analyzes the challenges faced by the deep and ultra-deep drilling technology，and points out the future development direction. With the exploitation of hydrocarbon resources shifting toward deep and ultra-deep formations，drilling technology faces many challenges，such as high temperature and high pressure （HTHP），complex geological structure，and wellbore instability. In recent years，significant progress has been made in the casing program optimization，ultra-deep drilling rig equipment，drilling fluid technology，etc.，but there are still vital problems，such as HTHP tolerance，wellbore instability and severe lost circulation. The future development of the casing program optimization technology is oriented toward intelligence and refinement to improve the risk warning accuracy and the dynamic adjustment ability of the casing program design. The rig equipment and key tools will focus on automation and intelligent upgrading to improve their tolerance of temperature and pressure and reliability. The drilling fluid technology needs to be further studied in terms of water- and oil- based drilling fluid systems tolerant of high temperature and high salinity and lost circulation control and plugging. These technological breakthroughs are expected to provide solid support for the efficient development of deep oil and gas resources. Reference | Related Articles | Metrics

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Numerical Simulation for Wax Forming Trend Considering Heat Loss in Small Size Vertical Pipes YANG Zaiguang , LIU Qiwei , WEI Kai, , LIU Yulong, , HAN Xuelong, Xinjiang Oil & Gas    2024, 20 (4): 44-49.   DOI: 10.12388/j.issn.1673-2677.2024.04.006 Abstract （27）      PDF （1603KB）（11）       Knowledge map    Save In the production process of flowing wells，the temperature gradients of oil streams are high in the axial and radial directions of wellbores，and the radial wax concentration is affected by Brownian motion and molecular dynamics，leading to highly variable gradients. Due to impurities such as resins and asphaltenes，wellbore precipitates are generated under the control of multiple factors such as oil stream temperature and ambient temperature，with consequences ranging from production reduction to wellbore blockage and thus production interruption. Given the high likelihood of crude oil wax forming with a low freezing point and high thermal sensitivity in an oilfield in western China，a finite element model of oil stream wax forming in small size vertical pipes was established based on thermodynamic model，and the latent heat often ignored in ideal solution models was incorporated. The wax forming trend in a wellbore was simulated using the numerical simulation software. The effects of ambient temperature，oil stream inlet temperature and oil flow Reynolds number on wellbore wax forming were studied. The results show that the wax deposition of crude oil with a low freezing point and high thermal sensitivity increases significantly in a low temperature environment with a low Reynolds number of oil flow. In order to avoid wax forming and blockage caused by heat loss in wellbore，oil stream temperature shall be controlled within 5-10 ℃ higher than the static wax deposition point. The findings of this research provide theoretical support for the prediction of wax forming trend and the determination of wax forming prevention measures during oilfield development. Reference | Related Articles | Metrics

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Research Progress on Early Warning Technology of Drilling Complex Accidents LIU Yingbiao, , XU Shengjiang, , TIAN Long, , ZHONG Yinming, , BAI Jiashuai, , ZHONG Runhao, Xinjiang Oil & Gas    2025, 21 (2): 15-23.   DOI: 10.12388/j.issn.1673-2677.2025.02.002 Abstract （25）      PDF （636KB）（9）       Knowledge map    Save Complex accidents in drilling operations，such as lost circulation，pipe sticking，and well kick，bring about severe threats to drilling safety and significantly increase economic costs. Therefore，the petroleum industry is driven to actively seek efficient preventive measures. With the rapid development of big data and artificial intelligence technologies，developing an early warning system for drilling complex accidents has become a core technical challenge in drilling engineering. This study conducts an in-depth exploration of the early warning technologies for drilling complex accidents，including lost circulation，sticking，and well kick. It systematically compares the characteristic parameters，accuracy，and application performances of various algorithm models and reveals the differenc es and advantages/disadvantages of different models in terms of early warning capabilities. It is found that in scenarios where the demand for characteristic parameters is low and the data sources are stable，machine learning algorithm models exhibit superior accuracy and timeliness in the early warning of drilling complex accidents. However，when faced with challenges such as high computational complexity，poor data quality，and unstable data sources，especially in predicting lost circulation during drilling and early-warning complex well kick accidents，the models suffer from high rates of false alarms and frequent missed alarms，and few field application cases are reported. To promote the field application of drilling complex accident early warning techniques and drilling digitalization，it is necessary to strengthen research on data quality improvement and algorithm optimization. Despite the numerous challenges，big data and artificial intelligence still open up broad prospects for early warning technologies. Reference | Related Articles | Metrics

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Xinjiang Oil & Gas    2025, 21 (2): 0-.   Abstract （19）      PDF （13856KB）（7）       Knowledge map    Save Related Articles | Metrics

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Intelligent Diagnosis and Analysis of Stuck Pipe Based on Supervised and Unsupervised Algorithms SONG Xianzhi, , WANG Yiwei , YANG Yanlong , LIU Muchen , ZHU Zhaopeng, Xinjiang Oil & Gas    2025, 21 (2): 24-34.   DOI: 10.12388/j.issn.1673-2677.2025.02.003 Abstract （19）      PDF （3087KB）（5）       Knowledge map    Save In drilling engineering，stuck pipe，as one of the common downhole complex issues，seriously affects drilling efficiency. Stuck pipe monitoring is crucial for ensuring the safety and efficiency of drilling operations. With the rapid development of artificial intelligence technology in recent years，new approaches have emerged for stuck pipe monitoring. However，the existing research on intelligent stuck pipe monitoring mainly focuses on the optimization and application of single unsupervised or supervised algorithm，leaving a gap of systematic comparative studies on these two types of algorithms with respect to stuck pipe monitoring. This study selects multi-dimensional drilling parameters such as bit position，hook height，and torque of ratary table as the study targets，according to distance correlation coefficients，constructs a comparative evaluation system involving classic unsupervised algorithms （AE，K-means，DBSCAN） and supervised algorithms （SVM，RF，LSTM），and analyzes the performance of these algorithms in estimating stuck pipe trends. The results show that compared with supervised algorithm，unsupervised algorithm delivers a increase of 12.5% in monitoring average accuracy and reductions of 37.1% and 27.6% in average false and missed alarm rates respectively. Unsupervised algorithm demonstrates greater advantages in cases of small sample sizes and absence of mechanistic constraints. The findings of this research provide references for model selection and optimization in intelligent stuck pipe monitoring for drilling engineering and promote the practical application of unsupervised algorithm in stuck pipe risk monitoring. Reference | Related Articles | Metrics