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Optimization of Well Shut-in Time after Fracturing in Jimusar Shale Oil Reservoirs ZHANG Yanjun , XU Shucan , LIU Yafei , WANG Xiaoping , GE Hongkui , ZHOU Desheng Xinjiang Oil & Gas    2023, 19 (1): 1-7.   DOI: 10.12388/j.issn.1673-2677.2023.01.001 Abstract （373）      PDF （3496KB）（104）       Knowledge map    Save Well shut-in after fracturing is of great importance for increasing the oil recovery and production of shale oil reservoirs. The key is to determine the shut-in time. At present，there is no systematic and effective method for determining the time of shut-in either in China or across the world. The pressure transmission of the fracture system，the ion diffusion of the produced fluid and the capillary force imbibition are the key problems to be solved for addressing the above challenges. With laboratory experiments and field analysis，a comprehensive determination method for the shut-in time for Jimsar shale oil reservoirs was developed by clarifying the microscopic pore characteristics，wettability，laminae，and imbibition flooding potential of Jimsar shale oil reservoirs and analyzing the existing methods used and characteristics of shut-in time determination. It is concluded that the Jimusar shale oil reservoir provides strong imbibition and diffusion ability，and well shut-in after fracturing contributes to the displacement of oil. The shut-in time can be determined comprehensively in accordance with the required equilibrium time of the wellhead pressure，imbibition，and production fluid salinity. To determine the post-fracturing shut-in time for Jimsar shale oil reservoirs，the synergy of micro-fracture fluid charging and matrix imbibition should be taken into consideration. Specifically，with the second turning point of wellhead pressure decline taken as the lower limit and the turning point for the stable rising of salinity as the upper limit，the optimal shut-in time is determined，considering the imbibition equilibrium. The shut-in time after fracturing for Well Q was optimized based on laboratory experiments and field data. The suggested shut-in time for Well Q is about 55 days. This study provides an important reference for optimizing the shut-in time after fracturing. Reference | Related Articles | Metrics

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Progress and Application of the Key Technologies of Deep and Ultra-Deep Well Cementing YU Yongjin, XIA Xiujian, WANG Zhiguo, LIAO Fuguo, LIU Binhui, DING Zhiwei, Xinjiang Oil & Gas    2023, 19 (2): 24-33.   DOI: 10.12388/j.issn.1673-2677.2023.02.003 Abstract （335）      PDF （1607KB）（107）       Knowledge map    Save Deep and ultra-deep reservoirs are strategic alternatives for increasing reserves and production of hydrocarbons. Recently，significant progress has been made in deep well cementing，especially for special cementing working fluid systems(such as high temperature-resistant cementing additives，cement slurry tolerant of high temperature and large temperature deferences and ultra-high temperature cement slurry)，high temperature-resistant spacer，cementing tools，and cementing technology such as precise managed-pressure cementing，gradual wellhead pressure-holding and prestressed cementing. The cement slurry and cementing technology developed independently in China have been applied to deep well cementing operations in Sichuan，Tarim and Bohai Bay and other basins，and present remarkable performance in the successful cementing operations of Well Pengshen 6，the deepest vertical well in Asia，and Well Hongxing 1，the first well in China featuring 8-section-and-8-completion，and Well Qiantan1，the well with the highest temperature in Dagang Oilfield. Nowadays，the increasing complexity of targets of hydrocarbon exploration and development leads to a series of new challenges for cementing deep and ultra-deep wells. Consequently，it is necessary to strengthen the research on the basic theory，key materials，working fluid system，functional tools and technologies for cementing deep and ultra-deep wells，so as to provide more powerful technical support for deep and ultra-deep oil and gas exploration and development. Reference | Related Articles | Metrics

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A Global Review of Technical Status and Development Trend of Drilling Fluids for Deep and Ultra-Deep Wells LIU Fengbao, SUN Jinsheng, WANG Jianhua Xinjiang Oil & Gas    2023, 19 (2): 34-39.   DOI: 10.12388/j.issn.1673-2677.2023.02.004 Abstract （331）      PDF （573KB）（123）       Knowledge map    Save Drilling fluid is the core technology of deep and ultra-deep drilling and completion，and is one of the key technologies determining the success of a drilling operation. In this paper，the difficulties facing drilling fluids of deep and ultra-deep wells were analyzed，including wellbore instability，failure of drilling fluids at high-temperature and high-salinity conditions，high friction and environmental protection. Moreover，the latest technical progress of water- and oil-based drilling fluids in both China and other countries was reviewed. It was concluded that there are still large technical gaps in temperature and salinity resistance of drilling fluids between domestic drilling fluid systems and foreign advanced technologies，and therefore，it is urgent to strengthen research and development  efforts in terms of failure mechanisms of drilling fluid agents，anti-ultra-high-temperature drilling fluid agents and supporting technologies for special formations. Reference | Related Articles | Metrics

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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 Abstract （279）      PDF （3625KB）（314）       Knowledge map    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. Reference | Related Articles | Metrics

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Application of Air-Foam Drilling in Well Chaitan1 SUN Lanjiang , ZHANG Shuxia , LI Baoqing , XING Chao , LIU Wan , ZHONG Ninglong Xinjiang Oil & Gas    2022, 18 (4): 1-6.   DOI: 10.12388/j.issn.1673-2677.2022.04.001 Abstract （219）      PDF （699KB）（63）       Knowledge map    Save In many areas of Qaidam Basin，such as Yingxiongling，Ganchaigou and Xiandong，the shallow strata have poor lithology， loose cementation，fracture development，and frequently-occurred loss-return leakage in the process of drilling，which have seriously restricted the speed of drilling and affected the safety of drilling. This is a regional problem that needs to be solved urgently. Well Chaitan1 is a risk exploratory well located in Xiandong area. Conventional drilling fluid was used for the drilling of the surface section hole with a diameter of 660.4 mm. Leakage during the drilling was huge，and the plugging effect was not satisfactory. Therefore，it no longer possessed conditions to continue with the drilling. By using air-foam drilling technique and selecting the most suitable foaming agent and inhibitor for this well，the problem of frequently-occurred loss-return leakage in shallow strata has been solved，and the drilling cycle has been greatly shortened. By using the technique of sand cleaning-casing running，safe casing running has been realized in the well section with instable borehole and irregular hole diameters. The successful application of air-foam drilling technique in the Φ660.4 mm hole of Well Chaitan1 provides an approach and technical reserve for solving the problems of low pressure and likelihood for leakage and collapse in shallow strata during drilling in Qaidam Basin. Reference | Related Articles | Metrics

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Research Progress and Application of Chemical Plugging Materials and Method for Carbon Dioxide Flooding ZHU Daoyi, SHI Chenyang, ZHAO Yanlong, CHEN Shengen, ZENG Meiting Xinjiang Oil & Gas    2023, 19 (1): 65-72.   DOI: 10.12388/j.issn.1673-2677.2023.01.010 Abstract （206）      PDF （1379KB）（88）       Knowledge map    Save Carbon Capture，Utilization and Storage （CCUS） technology is an important tool for the energy sector to enable efficient oil and gas production under the dual-carbon goal. Injecting CO2 into oil reservoirs can significantly enhance oil recovery. However，its mobility differs greatly from that of the crude oil，and there’s clear differentiation with oil and water，which results in a limited sweep efficiency of CO2. Therefore，it is urgent to develop efficient CO2 plugging materials and corresponding plugging control technologies to improve reservoir recovery and CO2 storage efficiency. This article explains the characteristics of plugging in the CO2 flooding process and gives an overview of the commonly used CO2 plugging materials and methods. It also describes their applications in oil fields across the world，and their potential for improving CO2 recovery and storage in Xinjiang Oilfield. This study is inspiring for the global research and development of plugging materials in the process of CO2 flooding in oilfields worldwide，and highlights the future direction of CO2 plugging technology in Xinjiang oilfields. Reference | Related Articles | Metrics

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Design of One-Trip PDM for the Ultra-Shallow Horizontal Well in Block Chepaizi and Its Application DONG Zhihui, YANG Zening Xinjiang Oil & Gas    2022, 18 (4): 33-37.   DOI: 10.12388/j.issn.1673-2677.2022.04.006 Abstract （203）      PDF （665KB）（26）       Knowledge map    Save Because the ultra-shallow horizontal well in Block Chepaizi of Xinjiang has shallowly-buried target layer, poor diagenesis, large difference in drillability, and very low and unstable angle-building rate, large-degree progressive displacement motor (PDM) is needed to control the trajectory of the angle-building section. A large-degree PDM has large torque during compound drilling, and is very likely to have screw failure, which is not conducive to safe drilling. For the drilling of horizontal section, it is necessary to trip out and replace the large-degree PDM with a small-degree one. A large-degree PDM can neither achieve trajectory control for the secondspud vertical section, the deviated section and the horizontal section in one trip nor satisfy the demand for safe drilling. The analysis shows the one-trip drilling technique for the ultra-shallow horizontal well in Block Chepaizi requires that the PDM should not only have a high angle-building rate, but also be able to reduce the torsional force produced by compound drilling, so as to prevent the screw from twisting off or breaking off. Based on this, short-bend point PDM that meets the requirements is optimized and designed, which has the distance from the bend point of a conventional one to the bottom of bit adjusted to 1.3 m from 1.8 m. After such adjustment, anglebuilding ability of the screw is basically unchanged, but the screw offset value is reduced from 0.056 m to 0.038 m, which further reduces the torsional force acting on the PDM enclosure under compound drilling conditions from 3.7 kN·m to 1.5 kN·m. The newly-designed PDM can effectively control the trajectory by way of slide drilling combined with compound drilling, and complete the directional drilling operation of the ultra-shallow horizontal well in Block Chepaizi in one trip. Reference | Related Articles | Metrics

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Design Optimization of Downhole Throttling for Gas Wells in Xinjiang Oilfield and Its Application  DU Junjun , CHI Ming , Xieraili·MAIMAITI , WANG Gang , WANG Wenwen , LIANG Haibo Xinjiang Oil & Gas    2022, 18 (4): 84-88.   DOI: 10.12388/j.issn.1673-2677.2022.04.015 Abstract （201）      PDF （751KB）（72）       Knowledge map    Save In order to meet the requirements of gathering and transportation pressure，and prevent wellhead hydrate freeze bloking，design optimization has been made for the downhole throttling process of high-pressure and medium/low-pressure gathering and transportation regarding well selection conditions，gas nozzle diameter，setting depth，and other key technical parameters based on the technological principle of downhole throttling，and wellbore temperature and pressure profiles have been simulated. The results show that the downhole throttling process can meet the pressure requirements of high-pressure and medium/low-pressure gathering and transportation，and effectively solve the problem of wellhead hydrate freeze bloking.  Reference | Related Articles | Metrics

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A Method for Determining Effective Injection-Production Well Spacing for Low-Permeability Reservoirs and the Application LING Haochuan, WU Zheng, WANG Jijun, SUN Qiang, GENG Hongliu Xinjiang Oil & Gas    2023, 19 (1): 23-26.   DOI: 10.12388/j.issn.1673-2677.2023.01.004 Abstract （193）      PDF （514KB）（35）       Knowledge map    Save To make full use of the actual oilfield production test data to determine the effective injection-production well spacing for low-permeability reservoirs，the parametric equation of mobility function with the oil productivity index and the starting pressure was obtained by considering the low-permeability starting pressure gradient. The equation and the production test data can be used to get the mobility and drainage radius of the tested reservoir intervals. The regression analysis found that there is a semi-logarithmic relationship between the effective injection-production well spacing of low-permeability reservoirs and the physical property. Based on the relationship curve，the effective well spacing for directional well pattern development for low-permeability reservoirs can be determined. The application shows that the worse the reservoir properties，the smaller the effective well spacing；the effective well spacing of low-permeability reservoirs is 2 times the drainage radius，which means the valid producing coefficient has to reach 78.5% to ensure high efficiency between the producers and injectors. Using this method，the effective well spacing map of Bohai B Oilfield at different mobility was obtained. It’s suggested that the well spacing should be set between 300 m and 450 m at physical property range of 5 mD  to 20 mD. Reference | Related Articles | Metrics

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Formation Mechanism of Hydrogen Sulfide in Thermal Recovery Wells of Bohai Offshore Heavy Oilfield XIAO Sa, LIU Yaqiong, CAI Jun, SUN Yubao, WANG Shaohua, CAI Yina Xinjiang Oil & Gas    2022, 18 (4): 38-43.   DOI: 10.12388/j.issn.1673-2677.2022.04.007 Abstract （191）      PDF （701KB）（29）       Knowledge map    Save Formation of H2S will bring great potential hazard to the safety of personnel and equipment in offshore oil fields. In order to determine the source of H2S in offshore heavy oil thermal recovery wells，the formation mechanism of H2S during thermal recovery development was investigated by conducting experiments. Simulated experimental study on the formation of H2S at different temperatures was carried out for the three reactions systems of heavy oil，heavy oil + distilled water，and heavy oil + water + core + methane. Besides， experiment was also conducted on the formation of H2S at high temperatures for sulfonate surfactant. The results show that for the heavy oil of Bohai S Oilfield，the concentration of H2S produced by the cracking and aquathermolysis of heavy oil increases with the increase in reaction temperature，and the organic gas produced is mostly the gas of light hydrocarbons below C5，with a small amount of C6+ gas. The aquathermolysis of heavy oil has caused the change in heavy oil composition. The contents of resin and asphaltene in heavy oil decrease，while the contents of saturated and aromatic components increase. This phenomenon becomes more obvious with the increase in reaction temperature. For the mixed system under study，at 200 ~ 300 ℃，aquathermolysis and TSR are dominant，which are the main sources of H2S；when the temperature reaches 350 ℃，cracking and TSR become dominant. At the same time，it is also found that it is very easy for sulfonate surfactant to produce H2S at high temperatures due to its instability at high temperatures. It is recommended that the use of sulfonate surfactant in the presence of steam be minimized in thermal recovery.  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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Perforation Adjustment Modes of Oil & Water Wells for Water Flooding in Thick Reservoirs  TIAN Hongzhao Xinjiang Oil & Gas    2022, 18 (4): 52-55.   DOI: 10.12388/j.issn.1673-2677.2022.04.009 Abstract （188）      PDF （736KB）（13）       Knowledge map    Save Targeted at the problems of uneven vertical water flooding and gradual deterioration of development effect in the reservoirs of block B in G Oilfield with thick oil layers during water flooding，and combined with the actual geological parameters，a waterflood mechanism model for thick reservoirs is established. The influence of different perforation adjustment modes and adjustment timing of oil and water wells on the effect of water flooding is simulated and analyzed，and the optimal mode for next step of adjustment is given. Study results show that all oil and water wells should be perforated for production in the waterflood process of reservoirs，and high water-cut layers should be sealed off in time so that production can return to upward layers one by one after oil wells have water breakthrough. The effect of oil-water gravity differentiation should be fully utilized，which not only prevents the rapid formation of preferential channels after oil wells are waterflooded，but also reduces water cut. In addition，large production thickness of oil wells is beneficial to maintain higher oil production rate and better economic benefits，which is worth being applied and popularized.  Reference | Related Articles | Metrics

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Advances in Study on Temperature-Resistant and Salt-Tolerant Fluid Loss Reducers for Water-Based Drilling Fluids YUAN Yuehui, QU Yuanzhi, GAO Shifeng, RONG Kesheng, YE Cheng, LIU Kecheng Xinjiang Oil & Gas    2023, 19 (2): 62-68.   DOI: 10.12388/j.issn.1673-2677.2023.02.008 Abstract （179）      PDF （597KB）（47）       Knowledge map    Save The high-temperature and high-salinity environment in deep well drilling can lead to failure of drilling fluid performance，causing well collapse，lost circulation and other accidents，resulting in reduction of drilling safety and efficiency. As one of the most important additives in the drilling fluid system，the fluid loss reducer can reduce filtration through gel protection，viscosity increase and plugging，minimize damage to the formation and maintain the stability of the wellbore. With the continuous increase of deep and ultra deep well operations in China，more and more high-temperature and high-pressure formations，salt gypsum formations and other harsh formations have been encountered during drilling. The research and development of temperature-resistant and salt-tolerant fluid loss reducers has become the key to addressing the challenges in enhancing the drilling fluid technology for high-temperature and complex wells. Three types of water-based drilling fluid loss reducer were described in this paper，including the fluid loss reducers made of natural polymers and modified materials，synthetic polymers and inorganic/organic composites. It summarizes the recent research results of temperature-resistant and salt-tolerant fluid loss reducers for water-based drilling fluids in terms of raw material composition，synthesis（modification） method and product performance，discusses the future development direction of temperature-resistant and salt-tolerant fluid loss reducers for water-based drilling fluids in China，and provides theoretical guidance for the development and application of temperature-resistant and salt-tolerant fluid loss reducers.  Reference | Related Articles | Metrics

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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 Abstract （177）      PDF （548KB）（55）       Knowledge map    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.  Reference | Related Articles | Metrics

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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 Abstract （172）      PDF （5519KB）（168）       Knowledge map    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. Reference | Related Articles | Metrics

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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 Abstract （170）      PDF （7836KB）（182）       Knowledge map    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. Reference | Related Articles | Metrics

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Optimization and Application of Strength Criterion for Wellbore Mechanical Instability Evaluation in Drilling YANG Hu, CHEN Hao, LI Yilin, SUN Weiguo, ZHOU Penggao Xinjiang Oil & Gas    2022, 18 (3): 1-5.   DOI: 10.12388/j.issn.1673-2677.2022.03.001 Abstract （158）      PDF （855KB）（64）       Knowledge map    Save There is a lack of theoretical guidance and practical optimization method for the selection of strength criteria in wellbore stability evaluation in field， which may lead to the deviation of the drilling fluid density used. The collapse pressure calculated by six strength criteria widely used in rock engineering had been compared. The results show that the collapse pressure calculated by D-Pi criterion is the highest ， followed by M-C criterion ， H-B criterion and D-Pc criterion ； the collapse pressure calculated by LAm criterion and W-Cm criterion is in the middle. Through field practice ， a set of method for strength criteria optimization and application has been summarized. Applying the optimized strength criterion to the wellbore stability evaluation in later drilling to optimize the design and use of drilling fluid density can not only ensure the wellbore stability ， but also improve the drilling speed and oil and gas discovery. This method has been applied in some blocks and strata of Junggar Basin ， and achieved good results ， which is proved to be of popularization and application value. Reference | Related Articles | Metrics

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Practices of Zipper Fracturing for Tight Reservoir Development with Small Well Spacing WAN Tao , QIN Jianhua , ZHANG Jing Xinjiang Oil & Gas    2022, 18 (4): 26-32.   DOI: 10.12388/j.issn.1673-2677.2022.04.005 Abstract （155）      PDF （4308KB）（51）       Knowledge map    Save A fully coupled hydrodynamic model and field monitoring data are used to reveal the changes in in-situ stress during zipper fracturing in tight conglomerate reservoir under the volumetric development pattern of small well spacing，and the corresponding propagation pattern of fracture network. In the case that horizontal well adopts mono-interval and multi-cluster，staggered fracture arrangement and zipper fracturing，there exist stress interferences between wells and fractures at the same time. A large amount of fluid is injected into the wells fractured first to increase the pore pressure and induce the change in in-situ stress field. The mass and pressure transfer effect of fracturing improves the minimum horizontal principal stress，and reduces the two-way stress difference，which preactively creates geomechanical conditions more conducive to the formation of complex fracture network. The development effect of Mahu volumetric development demonstration zone in Junggar Basin with small well spacing shows that the stimulation effect of intervals subjected to centralized batch fracturing is much better，primary well pattern is more advantageous for the deployment of centralized fracturing and putting into production，and the wells to be fractured later have a more complex fracture network. By reducing the well spacing and conducting zipper fracturing，the horizontal stress difference is reduced continually，and the interferences between artificial fractures are mitigated，which is conducive to the formation of complex fracture network，and can effectively improve the production and recovery factor.  Reference | Related Articles | Metrics

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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 Abstract （147）      PDF （789KB）（38）       Knowledge map    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. Related Articles | Metrics

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ZHANG Jingchun, , REN Hongda , YU Tianxi , YIN Jianyu , ZHOU Jian , ZHOU Hongtao Xinjiang Oil & Gas    2023, 19 (1): 27-34.   DOI: 10.12388/j.issn.1673-2677.2023.01.005 Abstract （138）      PDF （547KB）（76）       Knowledge map    Save Proppant is the key material for propping hydraulic fracturing，and its performance has a significant impact on the effect of fracturing stimulation，so the research on fracturing proppants has received extensive attention. This paper summarizes the research and application of fracturing proppants and related technologies，including conventional proppants such as quartz sand，ceramic proppant，and coated proppant，as well as new types of proppant and related technologies such as self-suspension proppant，gas-suspension proppant，and in-situ generated proppant reported in recent years，totaling 10 categories. Last but not least，the paper looks into the future development directions of proppants and related technologies to provide reference for researchers of proppants and further accelerate the development of proppant technology. Reference | Related Articles | Metrics

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Advances in Study on Rheology Modifier for Water-Based Drilling Fluids SUN Jinsheng, , YANG Jie, , RONG Kesheng , WANG Ren, , QU Yuanzhi, , LIU Fan, Xinjiang Oil & Gas    2023, 19 (2): 1-16.   DOI: 10.12388/j.issn.1673-2677.2023.02.001 Abstract （134）      PDF （7116KB）（82）       Knowledge map    Save The global oil and gas exploration is gradually moving from shallow layer to deep layer，conventional hydrocarbon resources to unconventional hydrocarbon resources，medium and high-permeability to low-permeability and low-grade，and shallow seas to deep seas. With the increasing drilling workload，fit-for-purpose drilling fluid technology is needed to provide support for high-performance drilling. High-performance drilling fluids are the key to safe，efficient，economical，and green drilling，and the drilling fluid rheology is the core parameter for evaluating the performance of the drilling fluid system. As an essential treatment agent for building the drilling fluid systems，rheology modifiers can enhance viscosity and shear，improve the yield point-plastic viscosity ratio and optimize shear thinning，so as to control the rheology of drilling fluids. In order to drive the research and development of new rheology modifiers for drilling fluids，this paper investigates and classifies the rheology modifiers for water-based drilling fluids at home and abroad，and summarizes the research results，application，and existing problems of various rheology modifiers. The future direction of rheology modifiers for water-based drilling fluid was also analyzed to facilitate the technical improvement of water-based drilling fluids. Reference | Related Articles | Metrics

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Xinjiang Oil & Gas    2023, 19 (1): 0-0.   Abstract （132）      PDF （12767KB）（58）       Knowledge map    Save Related Articles | Metrics

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Technology to Stimulate Xinjiang Fengcheng Super-Heavy Oil Reservoir Containing Muddy Interlayers by Drilling Multilateral Wells  DU Binghui , LIN Botao, , ZHANG Runxue , HUANG Yong Xinjiang Oil & Gas    2022, 18 (4): 44-51.   DOI: 10.12388/j.issn.1673-2677.2022.04.008 Abstract （129）      PDF （7091KB）（25）       Knowledge map    Save Muddy interlayers are developed in Fengcheng super-heavy oil reservoir in Xinjiang，featuring extensive distribution，large thickness and poor permeability. As a result，the steam chamber fails to effectively affect the reservoir near the interlayers during conventional SAGD and vertical well-assisted SAGD. Aiming at the engineering problem that muddy interlayers seriously impede the flow through reservoir，this paper takes a SAGD well group in Fengcheng Oilfield as the research object. By way of drilling multilateral wells through its upper interlayers from the steam injection well，water was injected stage by stage to increase the pressure and expand the capacity，so as to achieve the purpose of reservoir stimulation. In addition，a finite element calculation model of reservoir stimulation by increasing the pressure stage by stage for the SAGD of multilateral wells containing interlayers was also established. The calculation results show that the formation pore pressure increases significantly in the areas near the multilateral wells. The capacity expanding area starts from the intersection of the lateral well and the steam injection well，and gradually extends outward. Finally，the effective capacity expansion covers reservoir in the vertical direction of 10 m and the horizontal direction of 5 m. In this scope，the increase range of porosity increases with the increase in the viscosity of the injected fluid. On this basis，the curve of construction flow rate versus wellhead pressure was established to provide basis for the design of field construction parameters. After multilateral wells were drilled in the field，the well group was subjected to micro-fracturing for capacity expansion. Compared with other well groups in the same block，the preheating period of this well group was shortened by 60 days，the average daily production increased by 5.6 t/d after 300 days of normal production，and the oil/steam ratio increased by 0.05. This shows that the stimulation effect of super-heavy oil reservoir containing muddy interlayers by drilling multilateral wells is satisfactory. 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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Construction and Performance Evaluation of Nano Microemulsion Oil Displacement System#br# ZHENG Cunchuan, ZHANG Liwei, XU Jinshan, ZEN Meiting, FU Gaofeng, FU Yulong Xinjiang Oil & Gas    2023, 19 (1): 89-94.   DOI: 10.12388/j.issn.1673-2677.2023.01.013 Abstract （125）      PDF （1731KB）（52）       Knowledge map    Save Microemulsion flooding is an effective technology to improve oil recovery. Microemulsions were prepared using dodecyl betaine，isopropanol and 90 ~ 120 petroleum ether. The impact of Km，the ratio of cosurfactant to surfactant，on microemulsion was studied using the pseudo-ternary phase diagram method. The results show that with the increase of Km，the area of microemulsion formed increased first and then decreased，and reached the maximum when Km = 2. The nano-microemulsion oil displacement agent was prepared using the microemulsion dilution method. The particle size distribution and interfacial tension were measured by laser scattering system and spinning drop interface tensiometer，respectively. The results show that the average particle size is 149.0 nm when the concentration is 0.25 %，and the minimum interfacial tension is 1.780 44 mN/m when the concentration is 0.3 %. The properties of the nano microemulsion oil displacement agent were evaluated in the laboratory. The results show that it had good dispersion stability at different temperatures. The maximum foam height is 140 mm when the concentration is 0.5%；the maximum emulsification efficiency is 55.0% when the concentration is 0.3%；the maximum oil displacement efficiency is 88.39% when the concentration is 0.2%；when the concentration is 0.3%，the total oil recovery factor is 86.78%. Reference | Related Articles | Metrics

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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 Abstract （124）      PDF （8824KB）（98）       Knowledge map    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. 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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Evaluation of Uncertainty in Quality Testing of Grade G Oil Well Cement  DI Xinye , MA Jiang , QI Jing , LI Liangbing , ZHANG Wei Xinjiang Oil & Gas    2022, 18 (4): 12-19.   DOI: 10.12388/j.issn.1673-2677.2022.04.003 Abstract （123）      PDF （698KB）（11）       Knowledge map    Save With the development of metrology，measurement uncertainty has been widely applied to many fields，which reflects the testing level of a laboratory and the reliability of testing results. In order to improve the accuracy of the quality testing data of grade G oil well cement，the testing processes of all physical parameters were investigated and analyzed in respect of testing repeatability，sample weighing，and cement slurry preparation by building a mathematical model. A typical method to evaluate the uncertainty in testing the thickening time，free liquid content and compressive strength of grade G oil well cement was established. The evaluation results show that when the inclusion factor K is 2，and the thickening time of grade G oil well cement is 103.3 min，its spread uncertainty is 1.09 min； when the free fluid content is 3.71%，its spread uncertainty is 0.71%；when the compressive strength at 38 ℃ is 5.44 MPa，its spread uncertainty is 1.23 MPa. The factors affecting the uncertainty in the testing process were determined，which are mainly the testing repeatability of samples，and followed by the mass weighing of samples. In actual testing，the testing error should be minimized by improving the weighing process of the mixed materials and increasing the number of repeated testing of samples.  Reference | Related Articles | Metrics

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Well Selection Conditions of Velocity String Fluid Drainage and Gas Production Technology CHEN Rui Xinjiang Oil & Gas    2022, 18 (4): 67-73.   DOI: 10.12388/j.issn.1673-2677.2022.04.012 Abstract （122）      PDF （3342KB）（46）       Knowledge map    Save For gas field with high condensate oil content in its produced fluid and unsuitable for foam carrier technology，velocity string fluid drainage and gas production technology is selected. Because the technology has strict requirements for well selection conditions， the well selection conditions for the fluid drainage gas production technology of velocity string have been determined by analyzing such factors as critical liquid-carrying flow rate，liquid production，gas production，gas-liquid ratio，formation pressure，bottom hole flow pressure and remaining recoverable reserves of gas well. After Well P2 was subjected to an application analysis，the optimal size of velocity string，favorable gas-liquid ratio，unflowing pressure and unflowing recoverable reserves have been obtained. It solves the problem that the gas well maintains the production status through external and internal drainage，reduces the loss of natural gas blowout， and eliminates the risk of killing the gas well without timely drainage，which lays a solid foundation for the well selection conditions of this technology in the future. Reference | Related Articles | Metrics

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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 Abstract （121）      PDF （1771KB）（42）       Knowledge map    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. Reference | Related Articles | Metrics

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Experimental Research and Application of VHSD Dilatation Stimulation in Shallow Heavy Oil Reservoirs ZHANG Liwei Xinjiang Oil & Gas    2023, 19 (2): 69-74.   DOI: 10.12388/j.issn.1673-2677.2023.02.009 Abstract （120）      PDF （3036KB）（110）       Knowledge map    Save In the late development stage of heavy oil reservoirs by steam injection huff and puff，the vertical well + horizontal well pattern steam drive （VHSD） is considered an effective way to sustain the recovery of mature heavy oil blocks. However，due to the interlayer distribution，low formation pressure coefficient，and the presence of steam channels in mature heavy oil blocks，the resultant oil gain of this method is unsatisfactory. The SAGD dilatation stimulation technology for heavy oil recovery can effectively break through the interlayers between injection well and production well and improve the overall production degree of the reservoir. Therefore，it is necessary to perform in-depth investigation of the dilatation technology for heavy oil reservoirs in the context of the VHSD. A one-dimensional core dilatation experiment was carried out，and the results showed no considerable post-dilatation variation of the core porosity and yet，an increase in the effective permeability by about 200 times. Based on large scale three-dimensional physical modeling，a dilatation experiment under the VHSD well pattern mode was carried out. The experiment shows that：（1） When the horizontal well trajectory is parallel to the direction of the maximum principal stress，the dilatation area is larger；（2） The distance of less than 35m between the vertical well and horizontal well is conducive to the formation of the combined dilatation zone；（3） After the high-permeability channels are plugged，an effective dilatation zone can still be formed. The experimental results are applied to the field practice，which shows that the recovered degree of the horizontal section of the production horizontal well is increased by more than 15% and the well production is effectively improved. This research provides effective references for the optimization of key parameters of the dilatation stimulation of heavy oil reservoirs，and is of great significance for the continuous efficient development of mature heavy oil blocks. Reference | Related Articles | Metrics

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Study on Penetration Depth and Rock Breaking Mechanism of PDC Cutter in Different Percussion Drilling Methods LIU Wei, XI Yan, ZHA Chunqing, GUO Qingfeng, XU Zhaohui, Wang Wei Xinjiang Oil & Gas    2023, 19 (2): 17-23.   DOI: 10.12388/j.issn.1673-2677.2023.02.002 Abstract （120）      PDF （5746KB）（65）       Knowledge map    Save Based on actual engineering applications of conventional drilling and percussion drilling，and considering the material parameters and intrinsic model of rock dynamic mechanics，a numerical model of rock breaking of the cutters of Polycrystalline Diamond Composite（PDC） bit was established. The penetration depth，damage area，size of rock debris particles and rock breaking volume of PDC cutters under different percussive drilling models were compared and analyzed. The results show that the rock cutting pattern is very similar between the numerical simulation results and the laboratory physical experimental model of single-cutter. The penetration depth of single tooth of rotary，torsional，and combined percussive drilling increased by 19.8%，6.6% and 26.9% respectively compared with that of conventional drilling，and the combined percussive drilling saw the most significant increase in rate of penetration. When there is axial impact load during percussive drilling（such as combined percussive drilling or rotary percussive drilling），it will cause visible damage to the rocks below the cutting surface，which facilitates the “second cutting” after the drilling cutters turn 360 °，but large rock debris particles can be produced，so it is necessary to optimize the drilling fluid parameters to keep the wellbore clean. The fluctuation range of penetration depth of the cutter in torsional percussive drilling is small，which indicates that this method helps reduce the risk of bit stick-slip，and the rock debris particles produced are small which makes it easy to keep the wellbore clean. The research results are of great significance for the selection of different types of percussion drilling tools and tool parameters optimization.  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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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 Abstract （117）      PDF （1762KB）（40）       Knowledge map    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. Reference | Related Articles | Metrics

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Xinjiang Oil & Gas    2022, 18 (4): 0-0.   Abstract （115）      PDF （4475KB）（83）       Knowledge map    Save Related Articles | Metrics

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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 Abstract （114）      PDF （5579KB）（74）       Knowledge map    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.  Reference | Related Articles | Metrics

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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 Abstract （113）      PDF （7535KB）（45）       Knowledge map    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. Reference | Related Articles | Metrics

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Study on Main Controlling Factors of Water Production in Tight Gas Wells  LI JingSong, LIU Zixiong, KOU Shuangyan, ZHANG Xiuming, LIU Rumin, WANG Jinwei Xinjiang Oil & Gas    2022, 18 (4): 20-25.   DOI: 10.12388/j.issn.1673-2677.2022.04.004 Abstract （113）      PDF （513KB）（63）       Knowledge map    Save It is well known that water production is the main factor leading to low production and low efficiency of gas wells. However， due to the lack of understanding of the main controlling factors of water production，applying the conventional drainage gas production method is always of low efficiency. In order to comprehensively study the main controlling factors of water production，the cocoon stripping optimization algorithm by big data analysis is introduced to firstly establish a big data sample library for factors that may affect water production，including geological，engineering，drainage and production factors；secondly，all the data is cleaned to eliminate invalid data. After that，the single factor analysis is carried out to determine the positive and negative relationship of each factor；then，multifactor analysis is conducted to find out the main controlling factors affecting water production in tight gas wells. Finally，39 main controlling factors are found out by using elimination method and the main control equation of water production is established to define the effect of each factor on water production. The study shows that：the main factors that greatly affect water production are producible porosity and total porosity identified by logging，gas testing and production casing pressure，clay content，etc. In order to avoid the impact of water production on gas production in the later stage，the reservoir sections with larger producible porosity，larger total porosity and lower clay content are preferred for fracturing. Meanwhile，the production scheme shall be implemented in the production process to avoid excessive pressure difference which can aggravate formation water production，so as to provide a basis for taking effective treatment measures for water-producing gas well in the later stage.  Reference | Related Articles | Metrics

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Optimization Technology of Water Injection System for Low-Permeability Reservoir in Wellblock S  LI Benshuang , SI Yuanzheng , LI Lianqun , HE Fengqing , HE Ming , YUAN Peng Xinjiang Oil & Gas    2022, 18 (4): 62-66.   DOI: 10.12388/j.issn.1673-2677.2022.04.011 Abstract （112）      PDF （527KB）（18）       Knowledge map    Save The existing water injection system in Wellblock S mainly had such problems as insufficient equipment capacity，great pressure loss of main pipeline，seriously insufficient injection of injectors，tremendous equipment maintenance volume and cost，and polluted water in the station area. Later，the system was optimized by using the technologies of partial pressure injection，equipment configuration optimization，simulation，non-metallic pipeline for corrosion protection，and closed water injection. After optimization，the increase of daily injection in Wellblock S is 2 115 m3 /d，injection satisfaction rate of injectors is increased by 20.7%，the natural decline rate of reservoir production is decreased by 4.8%，and the efficiency of injection system is increased by 4.1%. Old injectors that failed to satisfy water injection requirements can now meet injection allocation requirements，the corresponding well group has a daily oil increase of 33.4 t，and the annual increase in earnings is CNY 26.75 million. The effect on improving quality and increasing earnings is remarkable.  Reference | Related Articles | Metrics

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Evaluate the Temporary Plugging Effectivity for Fractured Horizontal Wells Through Pump-off Pressure Drop Analysis Method XU Peng, XIANG Yuankai, LIU Ruining, LU Ming, CHEN Shengen Xinjiang Oil & Gas    2022, 18 (4): 79-83.   DOI: 10.12388/j.issn.1673-2677.2022.04.014 Abstract （112）      PDF （1521KB）（42）       Knowledge map    Save In Jimsar，the method of dense cutting+large section and multi-cluster is applied to most of the horizontal shale oil wells that have been subjected to volume fracturing for stimulation. In order to further improve the stimulation effectivity，the method of temporary plugging is used in field to promote even fracture initiation. To evaluate the effectivity of temporary plugging，this paper interprets the reservoir and engineering parameters before and after temporary plugging based on pump-off pressure drop data using fracturing software. According to the comparison and verification made by well testing software，the interpretation results are similar，and the conclusions are reliable and effective. This method is simple，easy to operate，and cost-effective，and provides powerful guidance for field test of temporary plugging. The study results show that after temporary plugging，the closure time of fractures is prolonged，the efficiency of fracturing fluid is improved，and the treatment zone permeability is reduced，which prove that the temporary plugging agent is effective in satisfactorily plugging areas with good physical properties. Reference | Related Articles | Metrics