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Guo Xusheng, Zhang Yu, Liu Chaoying, Li Meng, Liu Shilin, Shen Baojian Theoretical and technological progress, challenges, and development directions of oil and gas exploration of Sinopec during the 14 th Five-Year Plan period China Petroleum Exploration    2025, 30 (1): 1-14.   DOI: 10.3969/j.issn.1672-7703.2025.01.001 Abstract （1299）   HTML       Knowledge map    Save Based on a systematic review of the exploration achievements and theoretical technological progress made by China Petroleum&Chemical Corporation (Sinopec) in different fields since the 14 th Five Year Plan, the main challenges, development opportunities,and directions for oil and gas exploration have been proposed. Since the 14 th Five Year Plan, facing challenges such as relatively weak resource foundation and increasingly complex exploration targets, Sinopec has firmly adhered to its main business of oil and gas energy security, focused on expanding resources, increasing reserves, and expanding mining rights, increased efforts to expand and increase oil and gas resources, and achieved multiple strategic breakthroughs and theoretical technological innovations. Developing theoretical understanding of oil and gas accumulation in ultra deep marine fault controlled fractures and caves, and discovered Shunbei Oil Field; Tackle the theoretical and technological system of shale oil exploration in terrestrial fault basins, and promote sustained major breakthroughs in shale oil;Improve the theoretical understanding of “dual enrichment” of marine shale gas, and achieve leapfrog development in multi-layer shale gas exploration in the Sichuan Basin; Tackle the theory of tight detrital rock formation and reservoir formation, and cultivate multiple scale benefit enhanced storage sites; Tackling the mechanism of coalbed methane occurrence and enrichment, achieving strategic breakthroughs in deep coalbed methane; Significant breakthroughs have been achieved in the exploration of new marine areas such as the Beibuwan Basin. In the future, Sinopec will face three major development challenges: the reduction of mining rights, technological innovation in the exploration theory of “two deep and one non”, and the difficulty of efficient exploration. At the same time, it needs to seize four historical development opportunities: national energy security guarantee, China’s shale oil and gas revolution, green and lowcarbon transformation, and digital and intelligent upgrading. Sinopec will focus on five major projects for development, namely, leading the breakthrough in deep and ultra deep exploration in the central and western regions with the “Deep Earth Engineering”, leading the rapid transformation of mature exploration area resources with the “Shale Oil Demonstration Project”, leading the leapfrog development of unconventional natural gas with the “Shale Gas Demonstration Project”, leading the integrated benefit development with the “Tight Oil and Gas Storage Project”, and leading the new discovery of blue ocean strategy with the “Sea Area Breakthrough Project”. Sinopec will make greater contributions to ensuring national energy security and achieving the “dual carbon” goals. Reference | Related Articles | Metrics

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Hu Wenrui, Zhang Shutong, Xu Siyuan, Wang Xue Practice, challenges and prospects of oil and gas field development in China China Petroleum Exploration    2024, 29 (5): 1-11.   DOI: 10.3969/j.issn.1672-7703.2024.05.001 Abstract （869）   HTML    PDF （640KB）（53）    Knowledge map    Save Oil and gas enterprises face greater risks and challenges in ensuring national energy security associated with the deterioration of domestic oil and gas resources, greater difficulty in increasing reserves and production, continuously higher technical requirements, and constantly increasing development costs. In this context, the development practice of oil and gas fields in China over the past century is systematically reviewed, and the trends and composition of oil and gas reserves and production since the founding of the People’s Republic of China are analyzed in detail, which enable to reclassify the stage of oil and gas field development. Based on resource types of continental, marine, low-permeability, offshore, and shale oil and gas, oil and gas field development theory and technology are deeply summarized. Furthermore, the targeted countermeasures and suggestions are proposed by focusing on the challenges faced by the development of oil and gas industry at present, such as the extremely great difficulty in the innovation of exploration and development theories, demands for further improving the adaptability of unconventional oil and gas exploration and development technologies, high cost of oil and gas development, and the more significant contradiction between resource exploration and development and land lease and environmental protection. Combined with the new development situation, the study proposes that transforming towards intelligence is the fundamental path for the development of oil and gas enterprises, unconventional oil and gas development will occupy a major position in domestic oil and gas development, and green and low-carbon transformation is the inevitable trend for the sustainable development of oil and gas enterprises. Reference | Related Articles | Metrics

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Wang Qinghua, Yang Haijun, Li Yong, Cai Zhenzhong, Yang Xianzhang, Xie Huiwen, Chen Cai, Sun Chunyan Significant discovery and significance of oil and gas exploration Well Yetan1 of Kekeya peripheral in the Front Mountain of Southwest area of Tarim Basin China Petroleum Exploration    2024, 29 (4): 1-17.   DOI: 10.3969/j.issn.1672-7703.2024.04.001 Abstract （718）   HTML    PDF （6314KB）（11）    Knowledge map    Save The Yetan1 well in Kedong tectonic belt, west Kunlun thrust belt in the front mountain of southwest area of Tarim Basin, has made a major breakthrough in the Permian Pusige Formation, marking the discovery of an important exploration successor system in southwest area of Tarim Basin. Based on the regional geological data and the field outcrop, drilling and seismic research, the reservoir-forming conditions of the Permian Pusige Formation sandstone around Kekeya are reunderstood. A new round of research holds that the upper member of Permian Pusige Formation has a semi-deep lacustrine facies source rock with an area of 1.0×10 4km 2 and a maximum thickness of 800m. The organic matter abundance is 0.89%~1.5%. The source of organic matter is mainly bacteria and algae, and the type of organic matter is mainly type II. Hydrocarbon generation potential S 1+ S 2 is 1.47-2.78mg/g. Due to the tectonic uplift of the Kunlun Mountains, the lower member of the Permian Pusige Formation in the periphery of Kekeya subdivision entered the continental sedimentary system, and the delta front and shoal shallow lake sand bar high-quality sandstone reservoirs developed in the lower submember II, withsand body thickness of 42.5-63m and sand-land ratio of 27%-47%, which are a set of widely distributed reservoirs. It is a high quality reservoir-cap association with lower submember I of Pusige Formation and upper mudstone member of Pusige Formation. According to the structural pattern analysis after drilling of Yetan 1 well, it is concluded that the Kekeya subperipheral developed two phases of Indosinian and Alpine tectonic deformation, Palaeozoic imbricated thrust, strong overthrust, trap rows and belts, and the further extrusion and uplift in the Alpine period were partially complicated, and the imbricated thrust belt formed is a favorable exploration area. According to the analysis of natural gas dryness coefficient of the Pusige Formation, the R o is 1.31%-1.42%, which is similar to the maturity phase of the source rock, indicating that the oil and gas come from the foote overlying source rock and have undergone the accumulation process of early oil and late gas, and the accumulation has the characteristics of "hydrocarbon supply by the overlying foote, new layers produce and ancient layers storage, lower layers produce and upper layers storage, transport by fault ". Through re-comprehensive analysis, it is believed that the Permian Pusige Formation traps in this area are distributed in rows, and 9 traps are found, covering an area of 307.7km 2, with 286 billion square meters of natural gas resources and 143 million tons of condensate oil. Meanwhile, several favorable exploration targets such as PT1 well, PS1 well and PS2 well are selected and have great exploration prospects. It is expected to become an important replacement field for large-scale natural gas storage and production. Reference | Related Articles | Metrics

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Zhang Yu, Zhao Peirong, Gao Shanlin, Zhang Hua, Shen Baojian, Qian Keran, Wang Pengwei, Li Peng Practice and enlightenment of high-quality shale oil and gas exploration of Sinopec China Petroleum Exploration    2025, 30 (1): 15-25.   DOI: 10.3969/j.issn.1672-7703.2025.01.002 Abstract （714）   HTML       Knowledge map    Save Progress and achievements of shale oil and gas exploration of Sinopec are systematically reviewed, and major measures for highquality exploration are summarized. In addition, the future research directions of shale oil and gas are proposed. In recent years, Sinopec has implemented a series of measures for the high-quality shale oil and gas exploration, covering the full chain of planning, theoretical technology,engineering and management, which are characterized by “planning guidance promoted by top-level design, technological innovation promoted by basic research, economic benefits promoted by technological iteration, and large-scale reserve increase promoted by collaborative work”. As a result, a number of leading demonstration projects have been constructed, including marine shale gas in new strata and new areas in Sichuan Basin and multi-type continental shale oil in the eastern fault basins, which vigorously promotes the high-quality and collaborative development of shale oil and gas exploration in multiple fields. In the future, Sinopec will solidify the foundation of shale oil and gas resources,strengthen confidence in shale oil and gas exploration, continue to deepen and improve the “dual enrichment” theory, pursue the concept of value leading the overall situation, adhere to the six “integrated” operation modes, promote shale oil and gas strategic breakthroughs and discoveries with high quality, and identify positions for increasing reserves and production on a large scale, so as to make greater contributions to ensuring national energy security. Reference | Related Articles | Metrics

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Hou Yuting, Yang Zhaoyu, Zhang Zhongyi, Cheng Dangxing, Li Jihong, Liu Jiangyan, Zhang Yan Geological understanding and exploration potential of shale oil in the third submember of the seventh member of Yanchang Formation in Ordos Basin China Petroleum Exploration    2024, 29 (6): 17-29.   DOI: 10.3969/j.issn.1672-7703.2024.06.002 Abstract （557）   HTML    PDF （9398KB）（6）    Knowledge map    Save There are abundant shale oil resources in the seventh member of Yanchang Formation (Chang 7 member) in Ordos Basin. The largescale interlayered type shale oil reserves have been discovered in the first-second sub-member of Chang 7 member (Chang 7 1-2 sub-member), marking a major breakthrough in the exploration and development of continental shale oil. However, there is a low level of systematic study and evaluation of new type shale oil in the third sub-member of Chang 7 member (Chang 7 3 sub-member). By using SEM, 2D NMR, full field fluorescent thin section, and infrared spectroscopy analysis, as well as identification and evaluation techniques such as geophysical exploration and logging, geological understanding and oil enrichment mechanisms are summarized. The analysis shows that: (1) The laminated shale is composed of felsic-rich lamina, organic-rich lamina, tuffaceous-rich lamina, and clay-rich lamina. The pore type is dominated by intergranular pores, dissolution pores, and intercrystal pores, with a porosity of 2%–10% and an oil saturation of 68%–88%. (2) The mud laminar type shale is composed of clayey felsic siltstone, clayey felsic mudstone, and felsic clayey shale. The pore type mainly includes dissolution pores, intercrystal pores, and bedding fractures, with a porosity of 2%–6% and an oil saturation of 65%–75%. (3) The crude oil generated by organicrich shale in Chang 7 3 sub-member was retained and accumulated, and also accumulated in felsic-rich siltstone after micro migration, showing hydrocarbon retention–micro migration and enrichment pattern. The predicted favorable zone of laminated type shale oil in Chang 7 3 submember is 5000 km 2, and that of mud laminar type shale oil is 1600 km 2, with predicted reserves of up to one hundred million tons, showing huge exploration potential. Reference | Related Articles | Metrics

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Chen Xuan, Liu Juntian, Zhang Hua, Lin Tong, Gou Hongguang, Cheng Yi, Guo Sen Accumulation Conditions of Deep tight sandstone Gas in Taipei Sag and Enlightenment and Significance of Exploration and Discovery of Yuetan 1H Well China Petroleum Exploration    2024, 29 (6): 1-16.   DOI: 10.3969/j.issn.1672-7703.2024.06.001 Abstract （549）   HTML    PDF （7576KB）（9）    Knowledge map    Save Well Yuetan 1H in the Taipei Sag of the Tuha Basin made the first exploration discovery in the Badaowan Formation of the Xiaocaohu sub-sag, which achieved a comprehensive breakthrough in the exploration of the secondary sag area of the Taipei Sag and revealed the good exploration prospect of tight sandstone gas in the entire Taipei Sag area. Based on the Taipei Sag, this paper comprehensively analyzes the geological conditions of deep tight sandstone gas formation, and concludes that: (1) the development of three sets of source rocks in the Shuixigou Group provides a sufficient material basis for tight sandstone gas; (2) The development of delta front-scale sand bodies and near-coal seam sandstone dissolution pores are favorable reservoirs for deep tight gas accumulation; (3) The strata located in the lower part of the strike-slip thrust zone have good preservation conditions, which is a favorable area for tight sandstone gas enrichment. At the same time,based on the geological information obtained from the exploration and discovery of Well Yuetan 1H, the dominant accumulation conditions of Xiaocaohu sub-sag were clarified, and then the favorable geological conditions of tight gas in the entire Taipei Sag were re-understood, and it was pointed out that: (1) effective sand bodies were developed in the central area of the sub-sag; (2) The physical properties of the reservoir of the southern source sand body are better; (3) The source rock development zone with higher maturity is a favorable zone for natural gas enrichment. Based on the latest geological information and understanding, the evaluation of tight gas resources in Taipei Sag was re-carried out, and the predicted tight sandstone gas resources were 7070×10 8m 3, which was significantly higher than that in the previous period. Finally, the comprehensive evaluation selects two favorable exploration areas of tight sandstone gas in the northeast of Xiaocaohu sub-sag and north of Shengbei sub-sag. Reference | Related Articles | Metrics

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Wang Kaiming, He Xipeng, Gao Yuqiao, Liu Ming, Zhang Peixian, Sun Wei, Liu Nana Management and practice of exploration–reserve–mining rights integration in Nanchuan normal-pressure shale gas field China Petroleum Exploration    2024, 29 (5): 35-43.   DOI: 10.3969/j.issn.1672-7703.2024.05.004 Abstract （484）   HTML    PDF （1749KB）（45）    Knowledge map    Save In recent years, associated with the continuous advancement of mineral resources management reform in China, the original exploration procedures and mineral rights maintenance system of oil companies should be adjusted accordingly. As a result, the integration of exploration, reserve, and mineral rights with the core concept of “integrated research in all fields, integrated deployment in all aspects, and integrated operation in the whole process” has been proposed to realize the transformation from single-item scheme optimization to overall optimization and achieve the results of “1+1+1>3”. The integration of exploration, reserve, and mining rights mainly includes the following aspects: (1) Exploration discovery is the foundation, reserve evaluation is the key task, and the transformation from exploration to production is the ultimate goal. The systematic planning and collaborative promotion of the above three factors should be conducted to ensure the maximum comprehensive benefits of oil companies. (2) A big scientific research system based on the “three-dimensional integration” of technology, economy and policy should be constructed to consolidate the foundation for high-quality oil and gas discovery and high-efficiency transformation from exploration to production through high-quality scientific research; An integrated deployment system based on five key links of “drilling, fracturing, testing, production and sale” should be established, and the quality of deployment should be improved from the source by optimizing top-level design, dynamically optimizing and conducting real-time adjustments; A large operation system of “integration of various types of resources, and unified scheduling and operation” should be constructed, and the organization and operation of production should be optimized to ensure the improvement of speed, quality, and efficiency. (3) In the practice of exploration–reserve–mining rights integration, the “three unified” concept of conceptual identity, management consistency and technical collaboration should be established. From the conceptual perspective, the development consensus of maximum mineral rights interests should be kept in mind; The vertical integration and horizontal connection of management should be implemented, and the control mechanism of key nodes throughout the entire process should be constructed by integrating resources and optimizing procedures, so as to accelerate management reform and efficiency enhancement; The basic technological research should continuously been deepened, and the technological iteration and upgrade should be innovated to achieve the high-quality exploration breakthroughs and reserve increase on a large scale. The integration of exploration, reserve, and mining rights has been practiced in Nanchuan normal-pressure shale gas field in Southeast Sichuan Basin, obtaining remarkable results and developing a number of key technologies for exploration and development of normal-pressure shale gas, which have effectively supported the discovery and construction of Nanchuan normal-pressure shale gas field, with the new addition proven shale gas geological reserves of 1989.64×1 08 m3, new established mining rights area of 314.5971 km 2, the cumulative new constructed shale gas production capacity of more than 26× 1 08 m3, and the cumulative shale gas production of more than 65 ×1 08 m3 The application enables to build the first large-scale normal-pressure shale gas field in China that has been put into commercial development and achieve the high-efficiency transformation of the value of mineral rights, which has a positive role in unconventional oil and gas exploration and mineral rights management in China. Reference | Related Articles | Metrics

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Shi Yujiang, He Yufei, Wan Jinbin, Guo Xiaokai, Yu Hongguo, Yang Renjie Research on logging evaluation methods for geological quality and gas content of deep coal measure gas China Petroleum Exploration    2024, 29 (4): 128-145.   DOI: 10.3969/j.issn.1672-7703.2024.04.010 Abstract （448）   HTML    PDF （4993KB）（7）    Knowledge map    Save The deep coal measure gas is one of the key exploration and production targets in the field of unconventional oil and gas exploration,which has gradually grown to be a major source of natural gas resources in China. Compared with medium-shallow coalbed methane (CBM)reservoirs, the deep coal measure gas reservoirs are characterized by more complex gas occurrence and geological characteristics. For example,in B block in Ordos Basin, the deep coal measure gas shows higher gas content, better coal structure, poorer reservoir physical properties, and higher reservoir temperature, pressure, and formation water salinity than that in middle-shallow formations. The geological characteristics of deep CBM have systematically been analyzed, which support to summarize the typical logging response characteristics of coal seams, such as low density, low GR, high neutron, high acoustic time difference, and high resistivity, and achieve the identification of coal reservoir; After analyzing the different logging response characteristics of various coal structures, some logging parameters have optimally been selected to establish coal structure factors applicable for the target area and classify coal structure types; Based on experimental results and combined with logging response characteristics of target interval, a porosity logging interpretation model has been established by using variable matrix parameters of coal rocks; Based on the experimental data, the correlation between logging response and macerals has been analyzed, as well as that between macerals, which supports to construct a proximate component logging evaluation model in the target area; After conducting geological quality parameters evaluation such as coal seam identification, maceral calculation, and coal structure classification, the conventional and NMR-isothermal adsorption combined gas content evaluation technology has been developed to calculate both free gas and adsorbed gas in deep coal reservoirs, providing guarantees for the calculation of deep coal measure gas resources and reserves; Furthermore, with the aim of further improving the exploration efficiency and development benefits of deep coal measure gas, logging suggestions and technical research directions for the evaluation of deep coal reservoir have been proposed, so as to meet the goal of high-quality development of the deep coal measure gas industry. Reference | Related Articles | Metrics

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Duan Yanzhi, Guo Jiaofeng, Xu Shuping 10 th anniversary of oil and gas system and mechanism reform: achievements and prospects China Petroleum Exploration    2024, 29 (5): 12-20.   DOI: 10.3969/j.issn.1672-7703.2024.05.002 Abstract （431）   HTML    PDF （497KB）（46）    Knowledge map    Save In June 2014, at the sixth meeting of the Central Financial and Economic Leading Group, President Xi Jinping proposed to promote the energy consumption revolution, energy supply revolution, energy technology revolution, energy system revolution and strengthen comprehensive international cooperation, actively promote energy system reform, accelerate the formulation of the overall plan for the reform of power system and oil and gas system, and initiate the work of amending and abolishing laws and regulations in the energy sector, which provided fundamental guidance for deepening reforms, comprehensive green transformation, and high-quality development of oil and gas sector in China. In order to comprehensively grasp the overall requirements of the new energy security strategy in the new era, and the key works and main achievements of the reform of oil and gas system and mechanism, the key laws, policies, standards, and other documents related to the reform of oil and gas system and mechanism since 2014 are systematically summarized, and the main achievements are overviewed qualitatively and quantitatively. The study results show that Chinese government has persisted in promoting the reform of oil and gas system and mechanism for the past decade, and conducted a series of reform measures, including the construction of legal regulations and standard systems in oil and gas sector, transformation of government management functions in the oil and gas industry, guidance and construction of an oil and gas market system, and the promotion of oil and gas pricing mechanism reform, strongly supporting the increase of oil and gas reserves and production, as well as the acceleration of industry development. In the future, associated with the new journey of comprehensively building a socialist modernized country of China, the legal and regulatory system in oil and gas industry should be improved, a capable government and an effective regulatory system should be established, an “X+1+X” oil and gas market pattern should fully be constructed, and an oil and gas pricing mechanism of “controlling the middle and opening up both ends” should be formed, so as to comprehensively ensure the high-quality development of oil and gas industry. Reference | Related Articles | Metrics

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He Xipeng, Zhang Peixian, Gao Yuqiao, Wang Kaiming, He Guisong, Ren Jianhua, Gao Quanfang, Zang Suhua Challenges and countermeasures for beneficial development of unconventional oil and gas resources in China China Petroleum Exploration    2025, 30 (1): 26-41.   DOI: 10.3969/j.issn.1672-7703.2025.01.003 Abstract （421）   HTML       Knowledge map    Save Based on in-depth investigation on the differences in exploration and development, key technologies and operation modes of unconventional oil and gas at home and abroad, and integrated with the current situation of unconventional oil and gas exploration and development in China, some challenges in unconventional oil and gas industry are put forward, including strategic resource replacement,key development technologies, management system and mechanism, as well as digital intelligence and green construction. By referring to experience and enlightenment of “shale revolution” in North America, and focusing on key factors such as resource, technology, management,cost and benefit, five countermeasures and suggestions are proposed to promote the beneficial development of unconventional oil and gas in China: (1) Strategic planning in all domains. Strengthening the top-level design of development strategy, optimizing domestic resource base,and expanding overseas resource market to further consolidate the resource base for the large-scale development of unconventional oil and gas. (2) Full life cycle evaluation. Conducting long-term trial production test of single well to identify the production law, strengthening the evaluation of key pilot wells, conducting modeling and numerical simulation integrated study, and implementing development technological policies, so as to improve single-well production performance and enhance oil and gas field recovery factor. (3) Full-chain technology iteration. With the aim of addressing problems and achieving goals, researching on key core technologies for beneficial development,efficiently promoting the construction of unconventional oil and gas demonstration zones, and integrating feasible and replicable practices to comprehensively promote the beneficial development of unconventional oil and gas resources. (4) Overall planning of resources. Promoting the operation mode of “four integrations, diversified cooperation and market-orientation” to achieve production and efficiency improvement and mutual benefits, and enhance the vitality of unconventional oil and gas development. (5) Whole-process green and intelligent operation.Constructing a large scientific research system, a large operation system and a large environmental protection system to create a new development pattern of the unconventional oil and gas industry. The five countermeasures aim to promote the large- scale and beneficial development of unconventional oil and gas resources in China, ensure the sustainable and high-quality development of domestic oil and gas industry, and fulfill the major responsibility and mission of securing the energy rice bowl. Reference | Related Articles | Metrics

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Ma Yongxin, Zhang Qiaoliang, Lu Ruibin, Yu Chengchao, Ruan Hongjiang, Tang Xu, Wu Shaowei, Sun Shengxin Progress and development direction of development technology for low-permeability oil field in complex fault blocks in the western South China Sea China Petroleum Exploration    2024, 29 (3): 1-9.   DOI: 10.3969/j.issn.1672-7703.2024.03.001 Abstract （406）   HTML    PDF （12329KB）（4）    Knowledge map    Save The low-permeability oil field in complex fault block in the western South China Sea has a large reserve scale, which is a key target area for production capacity replacement in the near future. However, the fault block is characterized by small area, great burial depth of oil reservoir, and complex reservoir characteristics, leading to great challenge in high-efficiency oil field development. In view of the high reservoir heterogeneity, rapid reservoir changes in lateral, and complex main controlling factors for reservoir physical properties, the fine reservoir description technology has been used to accurately predict the distribution of “sweet spot” reservoir, which guides the deployment of development wells; In response to the poor development results by conventional seawater injection due to the strong water sensitivity of low-permeability reservoir, gas injection gravity auxiliary displacement and nanofiltration seawater displacement technology have been researched, and an effective displacement technology series for low-permeability oil fields has been established, improving the injection-production well pattern and enhancing the displacement results; By considering the limited well slot resources on offshore platforms, the technology of high-yield production with few wells has been adopted, and complex well structure has been applied to effectively improve the sweep range of single wells. Meanwhile, supporting technology for the high-efficiency development of low-permeability oil field has been researched and developed, which supports to integrate resources and revitalize internal and surrounding potential, laying a solid technical foundation for production increase of the western oil fields in South China Sea. Reference | Related Articles | Metrics

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Lei Qihong, Ma Fujian, He Youan, Wang Shuyu, Niu Li, Luo Yin, Ye Po, Huang Tianjing, Huang Zheyuan, Liu Yuan, Feng Zhangbin Characterization of natural fractures and reservoir reconstruction strategy for continental shale oil reservoir in Ordos Basin China Petroleum Exploration    2024, 29 (3): 130-145.   DOI: 10.3969/j.issn.1672-7703.2024.03.012 Abstract （361）   HTML    PDF （53988KB）（2）    Knowledge map    Save The shale oil reservoir in the seventh member of the Triassic Yanchang Formation (Chang 7 member) in Longdong area in Ordos Basin is mainly composed of alternating deposits of deep lacustrine shale and gravity flow sand bodies, with complex and variable reservoir distribution both vertically and laterally, and thin single sand body. In addition, influenced by natural fractures, there are a number of challenges in scientific fracturing engineering and production operation in the area. Some engineering problems such as pressure channeling and sand plugging, as well as cost reduction and production increase, are important research topics at present. The work and understanding on the characterization of natural fractures in the area in the past two years are summarized, and the latest concepts and strategies in fracturing reconstruction are introduced. On the basis of comprehensive geological study, 3D fine geological, oil reservoir, and geomechanical models have been established, and rational fracturing design, construction, post fracturing analysis, and computer simulation have been conducted to better understand the interaction between natural fractures and hydraulic fractures and the propagation law of hydraulic fractures, achieving the customized fracturing design and construction optimization. After field application, the amounts of proppant and fracturing fluid have been reduced by about 20% and 10%, respectively, given the similar oil production between the construction well and adjacent wells on the same platform. The workflow with integration of geology and engineering enables the implementation of “one well, one strategy” and “one section, one method”. In the long run, it will be the fundamental technical guarantee for achieving the best EUR of single well and well platform for continental shale oil in Ordos Basin. Reference | Related Articles | Metrics

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Yang Yuran, Shi Xuewen, Li Yanyou, He Yifan, Zhu Yiqing, Zhang Ruhua, Xu Liang, Yang Xue, Yang Yiming, Zhang Yichi Paleogeomorphology, sedimentary patterns and exploration of Deyang Anyue Rift Trough in Qiongzhusi Formation, Sichuan Basin China Petroleum Exploration    2024, 29 (6): 68-81.   DOI: 10.3969/j.issn.1672-7703.2024.06.006 Abstract （359）   HTML    PDF （33496KB）（3）    Knowledge map    Save The shale gas within the Deyang-An’gue sag, specifically in the Qiongzhushi Formation, exhibits significant exploration potential. The characterization of the sag’s depositional features during the sedimentary period of the Qiongzhushi Formation has not been systematically understood. By establishing a sequence stratigraphy framework for the deposition of the Qiongzhushi Formation and analyzing sedimentary landforms based on shale thickness and quality, the geological significance of shale gas is elucidated. The results indicate that, considering sedimentary landforms, sedimentary facies, shale thickness, etc., the sedimentary period of the Qiong 1-2 sub-section can be divided into three landform units: intra-sag, slope, and extra-sag. Ancient landforms and source materials jointly control the shale thickness and quality. The intra-sag unit develops a siliceous mud-shale microfacies, with a shale reservoir thickness exceeding 20 m. The slope unit develops (including) sandy mud-shale microfacies, with a shale reservoir thickness of 5 to 20 m. The extra-sag unit develops muddy sandy-shale microfacies, with a shale reservoir thickness less than 5 m. Reference | Related Articles | Metrics

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Zheng Majia, Guo Xingwu, Wu Ya, Zhao Wentao, Deng Qi, Xie Weiyang, Ou Zhipeng Cultivation practice and exploration breakthrough of geology and engineering integrated high-yield wells of ultra-deep shale gas in the Cambrian Qiongzhusi Formation in Deyang-Anyue aulacogen, Sichuan Basin China Petroleum Exploration    2024, 29 (3): 57-67.   DOI: 10.3969/j.issn.1672-7703.2024.03.006 Abstract （344）   HTML    PDF （6115KB）（4）    Knowledge map    Save The ultra-deep shale gas reservoir in the Cambrian Qiongzhusi Formation in Deyang-Anyue aulacogen in Sichuan Basin is characterized by old geologic age, large burial depth and high thermal evolution, leading to great difficulty in shale gas exploration and development. However, there is no direct experience to learn from both at home and abroad. In view of this, the idea of geology and engineering integration is applied to preliminarily establish the key technological system of “well deployment-drilling-fracturing-production” for cultivating high-yield wells of Qiongzhusi Formation shale gas: (1) Integrated well deployment. The understanding of “hydrocarbon accumulation controlled by aulacogen” is deepened, the distribution mode of high-quality reservoir is determined, and the technical limits for operating high-yield wells are clarified, supporting the optimization of well deployment. (2) Integrated drilling, logging, and geosteering. Based on the comprehensive evaluation of geological and engineering parameters, the optimum drilling target is selected, the well trajectory is optimized, and the geology and drilling integrated fine management is strengthened, which effectively guarantee the drilling rate of high-quality reservoir. (3) Integrated fracturing and reservoir stimulation. The integrated fracturing model is used to optimize fracturing design, forming fracturing technology of “promoting fracture complexity + expanding fracturing volume + highly fracture supporting + casing deformation prevention”, which effectively achieves the uniform fracture initiation, high-efficiency fracture propagation, full reservoir support and maximum reservoir stimulation volume. (4) Integrated fine management of flowback. The “four-factor” flowback and reservoir stimulation technology is developed, and the fine flowback and production analysis platform is established, which achieve the “double breakthroughs” of reservoir damage reduction and gas well stimulation. By using the above technology system, high-yield gas flow has been obtained in Well Zi 201 for the first time in China in the Cambrian shale reservoir with a depth of greater than 4500 m, and the replication of high-yield production has successfully been achieved in Well Weiye 1H, which support to initially identify a favorable area of nearly 3000 km 2 with the depth of shallower than 5000 m and gas resources of nearly 2×10 12 m 3. The high-yield well cultivation technology and method lay a solid foundation for solving difficulties in large-scale and high-efficiency development of ultra-deep shale gas in the Cambrian Qiongzhusi Formation. Reference | Related Articles | Metrics

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Mao Xinjun, Li Yanping, Liang Zeliang, Zhu Ming, Yao Weijiang, Li Shubo, Pan Tuo, Hu Zhengzhou, Wang Yang Hydrocarbon accumulation conditions and exploration potential of the Jurassic coal measure gas in Junggar Basin China Petroleum Exploration    2024, 29 (4): 32-44.   DOI: 10.3969/j.issn.1672-7703.2024.04.003 Abstract （339）   HTML    PDF （7608KB）（5）    Knowledge map    Save Two sets of coal seams are widely distributed in the Jurassic Xishanyao and Badaowan formations in Junggar Basin, and there are abundant coal measure gas resources. However, as a completely new field of natural gas, the level of basic research is low, and gas accumulation characteristics, enrichment laws and resource scale in the basin are unclear. In 2020, a risk exploration well CT1H was drilled to explore gas bearing property of deep coal rocks, and a maximum daily gas rate of 5.7×10 4 m 3/d was tested, as well as a steady gas rate of 2×10 4 m 3/d in trial production, confirming the high and steady production capacity of coal measure gas. A systematic study on coal rock petrological characteristics, reservoir performance, evolution characteristics and control factors for gas accumulation in coal measure strata has been conducted, which indicates that the thermal evolution degree of coal rocks is low, with a medium-low coal rank, and the coal reservoir in Xishanyao Formation is dominated by meso-macro pores, while that in Badaowan Formation is mainly micro-small pores; By combining with multiple factors controlling gas accumulation in coal measure strata, such as source rock, structure, coal reservoir, and abnormal gas logging shows, the potential fields of coal measure gas in the basin have been classified and evaluated. Two favorable exploration areas including Dinan-Baijiahai and Qigu areas have optimally been selected, and coal measure gas resources are more than 1×10 12 m 3 with a burial depth of 2000-4000 m. Reference | Related Articles | Metrics

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Xie Wuren, Wen Long, Wang Zecheng, Luo Bing, Zhou Gang, Li Wenzheng, Chen Xiao, Fu Xiaodong, Wu Saijun, Xin Yongguang, Hao Yi, Ma Shiyu Hydrocarbon accumulation conditions and exploration potential of deep–ultradeep carbonate rocks in Sichuan Basin China Petroleum Exploration    2024, 29 (5): 61-76.   DOI: 10.3969/j.issn.1672-7703.2024.05.006 Abstract （335）   HTML    PDF （11658KB）（46）    Knowledge map    Save The deep–ultra-deep carbonate rock series in Sichuan Basin have an area of about 10×10 4 km 2, with superposition and orderly distribution of source rock and reservoir, showing huge exploration potential. After systematically studying the basic petroleum geological conditions of deep–ultra-deep formation in Sichuan Basin, the possible exploration types and their exploration potential are analyzed, and the future exploration orientation is put forward. The study results show that: (1) The “rift–depression” structural cycle controlled the distribution of deep–ultra-deep carbonate reservoirs. Four sets of thick dolomite reservoirs were developed in the region, and their distribution was mainly controlled by sedimentary facies zones, with the most favorable reservoir developed in platform margin at the edge of the rift. (2) The structural pattern of multi-stage alternating uplift and depression controlled the widespread marine source rocks in Sichuan Basin, among which source rocks with the best quality included the Cambrian Maidiping Formation–Qiongzhusi Formation, Silurian Longmaxi Formation, and Permian Longtan Formation. (3) The conventional porosity type carbonate reservoirs were mainly developed in the Sinian–Cambrian and Permian in the northwestern and central–eastern Sichuan Basin, with burial depth of 6000-10000 m. Three types of hydrocarbon accumulation combinations were formed, i.e., lower source rock and upper reservoir, side source rock and side reservoir, and upper source rock and lower reservoir, with superior hydrocarbon accumulation conditions. The key zones for increasing reserves on a large scale include Dengying Formation platform margin and Changxing Formation reef flat in the northwestern margin of Yangtze Craton, and the reef flat in the lower combination in the Sinian and Permian in the eastern Sichuan Basin, with a resource scale of more than one trillion tons. (4) The unconventional marl reservoirs were mainly developed in the first member of Maokou Formation (Mao 1 member) and the second sub-member of the third member of Leikoupo Formation (Lei 32 sub-member), with integrated source rock and reservoir, burial depth of 3000-6000 m, and resources of more than 3×10 12 t, which is expected to be a major replacement field. The favorable area of Mao 1 member is mainly distributed in the eastern–southern Sichuan Basin, while that of Lei 32 sub-member was mainly distributed in the central Sichuan Basin. Reference | Related Articles | Metrics

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Yang Yanhui, Wang Yuting, Liu Zhong, Chen Biwu, Wu Chunsheng, Zhang Xueying, Dong Qing Strategy and practice of high-efficiency development of high-rank coalbed methane in the southern Qinshui Basin China Petroleum Exploration    2024, 29 (4): 18-31.   DOI: 10.3969/j.issn.1672-7703.2024.04.002 Abstract （333）   HTML    PDF （6864KB）（4）    Knowledge map    Save There are abundant high-rank coalbed methane resources in China, and the high-efficiency development is of great energy, security,and ecological significances. Taking the development practice of high-rank coalbed methane in southern Qinshui Basin as an example, five main problems and challenges in the early development process are systematically analyzed: (1) A lack of advanced theory for the development of high-rank coalbed methane; (2) Low accuracy of favorable area selection; (3) Insufficient adaptability of reservoir reconstruction technology; (4) Low efficiency and poor benefit of drainage-production control regime; (5) “Three difficulties” and “three highs” of the gathering and transportation system. PetroChina Huabei Oilfield Company has adhered to problem-oriented and target-oriented approach and integrated indoor research and field practice, forming a new concept and key technologies for the high-efficiency development of high-rank coalbed methane, which include a drainage development concept, and a development mode of single-lateral horizontal well casing + multistage fracturing; The technology for optimal selection of high-yield favorable areas has been researched, achieving the transformation from large-area overall production capacity construction to precise construction mode in the favorable area; The fracturing and reservoir stimulation technology for coalbed methane has been improved and updated, which supports to form multi-level effective fracture network; The optimal,fast and high-efficiency drainage-production control technology has been innovated; The low-pressure ring surface gathering and transportation technology has been developed to achieve high benefits. The field practice shows that the success rate of new constructed production capacity has increased from 37% to higher than 84%, the average daily gas production of a single well has increased by 1.6 times, the time reaching target production has decreased by more than 20%, and the cost of surface construction investment for new projects has reduced by 20%. In addition, the coalbed methane production breakthrough has been achieved in all types of reservoirs in Qinshui Basin, with an annual production capacity of 21×10 8 m 3 in coalbed methane field in the southern Qinshui Basin, which is it the largest coalbed methane field in China, greatly boosting the strategic development of coalbed methane. Reference | Related Articles | Metrics

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Wu Jianfa, Zeng Bo, Huang Haoyong, Cui Shuai, Zhao Shengxian, Changcheng, Gou Qiyong The Practice effect and understanding of the Integration of Geological Engineering of Shale Gas in Southern Sichuan China Petroleum Exploration    2024, 29 (3): 80-90.   DOI: 10.3969/j.issn.1672-7703.2024.03.008 Abstract （330）   HTML    PDF （13952KB）（2）    Knowledge map    Save The integrated technology of geological engineering in south Sichuan shale gas not only successfully solved the engineering challenges under complex geological conditions, but also significantly increased the production and EUR per well. This paper summarizes the basic concept, core connotation and technical system of the integration of geological engineering of shale gas in southern Sichuan, and puts forward the cultivation method of high production well suitable for different blocks and different conditions. The results show that: (1) the integrated technical system of geological engineering provides important decision-making basis and guidance for the scheme design and on-site implementation of shale gas wells in the whole life cycle, and effectively solves the bottleneck problems of "pressure channeling" and "casing deformation". The casing deformation and pressure channeling rate in Luzhou block are reduced by 19% and 31%. (2) Continuous iterative updating of geological engineering feature understanding and integrated model can significantly improve the accuracy, reliability, consistency and effectiveness of the design; (3) The implementation of the integrated high-yield well cultivation method of geological engineering can significantly increase the production of a single well, among which the average EUR of wells in Changning block increased to 1.30×10 8m 3, an increase of 26.2%; The average EUR of wells in the western Chongqing block increased to 1.53×10 8m 3, an increase of 36%. This method has been applied to different shale gas blocks in southern Sichuan, and remarkable results have been achieved, which verifies the importance of this method in improving the production and economic benefits of a single well, and can also provide reference for the economies of scale development of unconventional oil and gas reservoirs at home and abroad. Reference | Related Articles | Metrics

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Guo Gang, Su Shengmin Characteristics and main controlling factors for vertical hydrocarbon migration along faults: a case study of Pinghu slope in Xihu Sag, East China Sea Basin China Petroleum Exploration    2024, 29 (3): 117-129.   DOI: 10.3969/j.issn.1672-7703.2024.03.011 Abstract （330）   HTML    PDF （3615KB）（6）    Knowledge map    Save The vertically differential hydrocarbon enrichment in Pinghu slope in Xihu Sag was significantly controlled by faults. But there is a poor correlation between the timing of fault activities and the period of hydrocarbon accumulation, that is, faults were inactive (hereinafter referred to as “static faults”) in hydrocarbon accumulation periods. As a result, a clear understanding on the characteristics and main controlling factors for vertical hydrocarbon migration along static faults enables to provide a theoretical basis for petroleum exploration in Xihu Sag or similar areas. The comprehensive wireline logging, mud logging, seismic data, and core testing data such as homogenization temperature and salinity of inclusions, and rock pyrolysis are used to analyze the hydrocarbon supply formations and periods of hydrocarbon accumulation, and determine characteristics and main controlling factors for vertical hydrocarbon migration along statistic faults. The study results show that hydrocarbon was supplied by the good-superior mature source rocks in Pinghu Formation and Baoshi Formation, and vertically enriched in the middle-upper parts of Pinghu Formation, showing characteristics of lower source rock and upper reservoir. Two stages of hydrocarbon charging occurred during the deposition periods of Yuquan-Liulang Formation and Santan Formation-present. While faults were mainly active during the deposition period of Baoshi-Longjing Formation, which had poor matching relationship with hydrocarbon accumulation period, and hydrocarbon migrated vertically along static faults in the late stage. The influencing factors for the vertical hydrocarbon migration along static faults include the width of fault zone, source rock pressure, and displacement pressure in the fault zone. In the study area, the width of fault zone ranges in 138-288 m, which has a positive correlation with the distance of vertical hydrocarbon migration. The source rock pressure experienced a complex evolution process, with a slightly lower pressure in the hydrocarbon accumulation period than the present, but still weakly overpressure or overpressure. The higher the pressure coefficient at present and during the hydrocarbon accumulation periods, the longer distance of vertical hydrocarbon migration. The displacement pressure in the fault zone ranges in 0.2-3.5 MPa, and it shows a negative correlation with the distance of vertical hydrocarbon migration. Based on the relationship between three influencing factors and the distance of vertical hydrocarbon migration, a quantitative evaluation formula for the vertical transport capacity of faults is developed, and the evaluation results indicate a distinctly positive correlation with the maximum hydrocarbon migration distance, according to which the favorable exploration targets in Pinghu slope are determined, including Pinghu Formation and the lower member of Huagang Formation near F2 and F5 faults. Reference | Related Articles | Metrics

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Lin Yongmao, Lei Wei, Miao Weijie Practice of geology and engineering integration in deep tight gas development: a case study of Xujiahe Formation in western Sichuan Basin China Petroleum Exploration    2024, 29 (3): 21-30.   DOI: 10.3969/j.issn.1672-7703.2024.03.003 Abstract （315）   HTML    PDF （11794KB）（3）    Knowledge map    Save There are abundant natural gas resources in Xujiahe Formation in Xinchang-Hexingchang in western Sichuan Basin, with proven reserves of 1700×10 8 m 3 in Sinopec exploration blocks. The reservoir is characterized by “one-deep, two-high, and two-low”, including great burial depth of gas reservoir (4500-5500 m), high formation pressure (pressure coefficient of 1.4-1.7), high fracture pressure (110-165 MPa), ultra-low porosity (average of 3.7%), and ultra-low permeability (average of 0.07 mD), which brings multiple challenges to geological theoretical understanding and high-efficiency gas development, and restricts the progress of exploration and development. Based on the research idea of geology and engineering integrated practice, understanding of tight sandstone gas migration and accumulation has been deepened, and gas accumulation mechanism and enrichment and high-yield production laws have been identified. By starting from the detailed analysis of development mode of geological sweet spots, the formation mechanism of gas reservoir sweet spots has been determined, and a sweet spot geological model has been established. By applying fracture and reservoir fine seismic characterization and quantitative prediction technology, and optimizing drilling and reservoir reconstruction technologies, the geology and engineering integrated collaborative research on key technologies such as geology, geophysics, drilling and completion has been conducted, and the practice of technology and economy integration has been implemented. The successful application of technical sequences supports the large-scale production of the gas field, with a cumulative production capacity of over 10×10 8 m 3, and new addition proven geological reserves of 1300×10 8 m 3 in Hexingchang Gas Field, which further confirms that the integration of geology and engineering is a necessary way for the effective development of low-grade gas reservoirs, promotes the beneficial development of Xujiahe gas reservoir in western Sichuan Basin, and provides reference for the exploration and development of tight and difficult to use reserves, especially deep tight gas. Reference | Related Articles | Metrics

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Zhang Ruifeng, Wang Haoyu, Feng Guangye, Liu Jing, Chen Shuguang, Peng Yu, Wang Danling Major oil and gas discovery and exploration potential in ultra-deep formation in Well Hetan 101, Hetao Basin China Petroleum Exploration    2024, 29 (5): 77-90.   DOI: 10.3969/j.issn.1672-7703.2024.05.007 Abstract （313）   HTML    PDF （18459KB）（46）    Knowledge map    Save Hetao Basin, a proliferous basin showing rapid subsidence and hydrocarbon accumulation in the late stage, has abundant oil and gas resources. In order to identify the potential of ultra-deep oil and gas reservoirs in sub-sag area in Linhe Depression, Well Hetan 101 was deployed and drilled in Guangming structure, and a significant breakthrough was made in Linhe Formation at a depth of greater than 6500 m, with an oil rate of 1285.77 m 3/d and a gas rate of 1×10 4 m 3/d. A comprehensive study on hydrocarbon accumulation conditions in the deep to ultra-deep formations in the sub-sag area has been conducted. The study result suggests that the reservoir sand body has the characteristics of high rigid particle content (average of 85%), low geothermal gradient (2.3 ℃ /100m), long-term shallow burial–late deep burial, and low interstitial material content (less than 5%), enabling the preservation of abnormally high-porosity reservoirs at a depth of greater than 6500 m. The pressurization after hydrocarbon generation and under-compaction of mudstone provided driving force for hydrocarbon migration. However, due to the influence of detachment faults, over-pressure only occurred in Guangming structure, with formation pressure coefficient reaching up to 2.0–2.3 in the sub-sag area, forming a self-generation and self-storage type structural oil and gas reservoir with co-occurrence of source rock and reservoir. The vertical fractures in source rock formed by hydrocarbon generation connected multiple sets of source rocks and high-permeability sand bodies, forming ultra-high pressure oil and gas reservoirs both in source rock and reservoir in ultra-deep formations with connected pores and fractures. The successful drilling of Well Hetan 101 once again confirms the broad prospects of petroleum exploration and development in deep and ultra-deep formations in continental fault basins. Guangming structure is expected to become a new large-scale integral and high-efficiency reserve area, demonstrating a new exploration field with high-yield oil and gas in ultra-deep formation, and providing a solid resource guarantee for the construction of a million–ton–level oil field in Hetao Basin. Reference | Related Articles | Metrics

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Wei Zhaosheng, Qin Jianhua, Li Yingyan, Li Xiao, Hou Haodong, Zhao Mingzhu, Yang Wei Differential diagenesis of mud shale and its influence on reservoir capacity: a case study in Lusaogou Formation, Jimsar Sag China Petroleum Exploration    2024, 29 (6): 99-115.   DOI: 10.3969/j.issn.1672-7703.2024.06.008 Abstract （311）   HTML    PDF （12068KB）（3）    Knowledge map    Save Mixed shale oil reservoirs are characterized by diverse rock fabric and lithofacies types, significant differentiation in diagenetic evolution, strong heterogeneity in micro-pore structure, complex genetic mechanism of micro-pore and fracture system and effective storage and permeability space. Taking the mixed shale oil reservoir of Lucaogou Formation in Jimsal Depression as the research object, the diagenetic types and diagenetic facies types of the shale layer of Lucaogou Formation were defined and the differential rock formation and reservoir formation mechanism of the mixed shale oil reservoir was revealed by comprehensive analysis and testing methods such as cast thin section, field emission scanning electron microscopy, X-ray diffraction, high pressure mercury injection and nitrogen adsorption. The results show that the diagenesis types of mixed shale oil reservoirs in Lusaogou Formation are diverse, including compaction, cementation and dissolution. According to the key diagenetic types and characteristic fabric, diagenetic facies can be divided into tuffe-feldspar dissolution phase, mixed cementation dissolution phase, chlorite film dissolution phase, carbonate junction phase and mixed cementation compact phase. The dissolution phase of tuffaceous feldspar is dominated by the dissolution pores of feldspar and tuffaceous, which are mainly in the range of 50-800 nm, and the total pore volume is the largest, which is the result of partial or complete dissolution of feldspar particles. The combination of solution pores and residual intergranular pores is developed in the mixed cementation phase, mainly in the range of 50-400 nm. It is the result of the superposition of carbonate, siliceous cementation and feldspar dissolution, and the total pore volume is the largest. The cement phase of chlorite film is dominated by residual intergranular pores with small pore size, and pores less than 50 nm are dominant. The heterogeneity is the weakest in all diagenetic phases, and the total pore volume is in the middle in all diagenetic phases, which is the result of corrosion and anti-compaction. The development of intergranular solution pores in carbonate cementation phase is dominated by pores in the range of 20-50 nm, which is the result of dissolution and carbonate cementation. All kinds of pores in the dense phase of mixed cementation are not developed, mainly in the range of less than 50 nm, which is the result of the comprehensive failure of compaction and cementation. Tuffaceous feldspar dissolution phase, mixed cementation dissolution phase and chlorite film phase are the dominant diagenetic facies types, while carbonate cementation phase and mixed cementation dense phase are not conducive to forming good reservoir conditions. This understanding is conducive to further understanding the differential formation process and mechanism of mixed shale oil formations. This finding helps deepen the understanding of the differentiated reservoir-forming processes and mechanisms of mixed shale oil layers, serving the precise prediction and efficient exploration and development of favorable shale oil production areas in the Jimusar Depression. Reference | Related Articles | Metrics

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Liu Gang, Yang Wenjing, Jing Xianghui, Bai Haifeng, Shi Baohong, Sun Yaping, Ren Junfeng, Pan Xing, Zhang Jianwu, Wei Jiayi Geological characteristics and exploration prospects of the Mesoproterozoic Changcheng System in Ordos Basin China Petroleum Exploration    2024, 29 (5): 44-60.   DOI: 10.3969/j.issn.1672-7703.2024.05.005 Abstract （305）   HTML    PDF （12688KB）（48）    Knowledge map    Save The Mesoproterozoic Changcheng System was the first set of sedimentary cap rocks in Ordos Basin, with a wide distribution area but low degree of study and exploration. By using field outcrops, drilling results of risk exploration well PT1, and 3D seismic data, a systematic study is conducted on stratigraphic correlation and distribution, sedimentary facies, and source rock characteristics in the Changcheng System. In Ordos Basin, five sets of formations were developed in Changcheng System from bottom to top, including Xiong’er Group, Baicaoping Formation, Beidajian Formation, Cuizhuang Formation, and Luoyukou Formation. The stratigraphic distribution characteristics vary in various rift troughs. In Jinshan rift trough, the five sets of formations were developed completely. In Dingbian rift trough, three sets of formations were developed, including Xiong’er Group, Baicaoping Formation and Beidajian Formation. While only Beidajian Formation was developed in Helan rift trough. The bathyal–shallow marine–coastal–delta sedimentary system was dominant in Changcheng System, intercalated with tidal flat deposits. Effective source rock in Cuizhuang Formation was encountered in Zhongtiaoshan in Xiong’er rift and several exploration wells in the secondary rift troughs, with the highest organic carbon content of 1.52% and average R o of 2.32%, showing potential of large-scale hydrocarbon generation. The basin thermal evolution simulation shows that Cuizhuang Formation source rock entered the mature stage in the Middle Permian with R o value of 0.5%, and entered dry gas generation stage in the late stage of the Early Cretaceous with R o of 2.0%. The comprehensive study shows that the configuration between source rock and reservoir in Changcheng System was good in Ordos Basin, forming self-generation and self-storage type natural gas reservoirs. Furthermore, two exploration targets are optimally selected in Dingbian rift trough and Jinshan rift trough, providing direction for gas exploration “towards source rock” in deep formations in the basin. Reference | Related Articles | Metrics

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Li Mingzhai, Cao Yimin, Ding Rong, Deng Ze, Jiang Ke, Li Yongzhou, Yao Xiaoli, Hou Songyi, Hui Hui, Sun Xiaoguang, Yi Wei, Sun Xiaoyi, Cao Xinxin Gas occurrence and production characteristics of deep coal measure gas and reserve estimation method and indicators in Daning-Jixian block China Petroleum Exploration    2024, 29 (4): 146-159.   DOI: 10.3969/j.issn.1672-7703.2024.04.011 Abstract （301）   HTML    PDF （745KB）（5）    Knowledge map    Save The deep coal measure gas is a new field of CBM exploration, and the scientific estimation of deep coal measure gas reserves is a new challenge. By summarizing the exploration and development achievements in Daning-Jixian block, and analyzing gas accumulation characteristics, occurrence pattern, gas production laws and performance of deep coal measure gas, the unique occurrence characteristics of adsorbed gas + free gas, gas production mechanism of free gas → free gas + adsorbed gas → adsorbed gas, and its significant differences from shallow and medium-shallow coal measure gas have been studied. Furthermore, the inadaptability of the current reserve estimation standards for deep coal measure gas has been pointed out in terms of estimation methods, unit division, estimation parameters, threshold for calculation,and data collection. Based on the above research, the following suggestions are put forward for estimating deep CBM reserves. The volume and volumetric methods can be used to estimate reserves, and the appropriate method should be selected based on the proportion of free gas;The reserve calculation units for free gas should be divided separately; The lower limit for coal gangue thickness deduction is 0.3-0.5 m; When R o is less than 1.0%, the lower limit for net coal seam thickness should be greater than 1.0 m; When R o is larger than 1.0%, the lower limit for net coal seam thickness should be greater than 0.8 m; The lower limit for single well gas production should be determined by well depth range and well type; In the early exploration stage, the recovery factor of vertical wells was 30%-45%, while that of horizontal wells was 35%-55%.This study provides technical references for the exploration and development, as well as reserve estimation of deep coal measure gas. Reference | Related Articles | Metrics

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Lu Zhiyong, Liu Li, Jiang Yuling, Zhang Qian, Zhan Xiaohong, Xiao Jialin Practice of geology and engineering integration in the stereoscopic development of Fuling Gas Field China Petroleum Exploration    2024, 29 (3): 10-20.   DOI: 10.3969/j.issn.1672-7703.2024.03.002 Abstract （298）   HTML    PDF （3555KB）（4）    Knowledge map    Save In view of the insufficient utilization of residual gas reserves by primary well pattern development in Fuling Shale Gas Field, geology and engineering integrated stereoscopic development technology is the core means to improve gas recovery and achieve accurate utilization of residual gas reserves. As a result, a new high-efficiency shale gas development mode with geology and engineering integration has been established, and shale gas modeling and simulation integrated technology has been innovatively developed to conduct fine research and identify the distribution of residual shale gas; The coupling of geological and engineering double sweet spots enables to determine the gold target window of well drilling trajectory, and the classification standard system of “resource + stress + natural fracture” three-in-one layered benefit combination has been established; Based on the differential distribution pattern of residual gas, the drilling and fracturing optimization design process has been established with “geology-drilling-fracturing-surface collaborative optimization”; By using real-time monitoring, the dynamic adjustment of well drilling trajectory and fracturing construction has been conducted, and integrated data sharing platform and real-time decision system have been constructed. The geology and engineering integrated stereoscopic development technology has guided the development of Jiaoshiba block and increased estimated recovery rate from 12.6% to 23.3%, and up to 39.2% in the stereoscopic development zone. The application of this technology supports to reduce shale gas drilling and production investment, and billion square meter production capacity construction investment and development costs year by year, which effectively guides the recovery enhancement and high-efficiency development of Fuling Shale Gas Field. Reference | Related Articles | Metrics

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Li Zhi, Dou Lirong, Shang Fei, Yang Zi, Qu Junya, Hou Ping, Li Fuheng Benchmarking and insights from implementation performance of risk exploration projects of key foreign oil companies China Petroleum Exploration    2024, 29 (5): 21-34.   DOI: 10.3969/j.issn.1672-7703.2024.05.003 Abstract （287）   HTML    PDF （739KB）（46）    Knowledge map    Save The international oil companies have adhered to a long-term exploration strategy of implementing risk exploration in global frontier domains to achieve substantial investment returns. However, there are considerable differences in their focus and implementation performance of risk exploration among various companies. In order to study the risk exploration strategies, risk exploration preferences, and implementation performance of foreign oil companies, and to guide the overseas petroleum exploration work of Chinese oil companies, oil company annual reports, public information and commercial database are used to analyze risk exploration projects of eight foreign oil companies during 2005–2022. As a result, an evaluation indicator system for project implementation performance has been established, including four primary indicators such as exploration benefits, exploration investment, project scale, and risk control, as well as 19 secondary individual indicators. The benchmarking of individual and comprehensive indicators is conducted, and the effectiveness and experience in risk exploration of the benchmarking companies are analyzed. The study results show that there are significant differences in the individual indicators among oil companies, which are closely related to their exploration strategies and risk exploration preference. ExxonMobil scores the highest in comprehensive evaluation indicators, while BP has relatively low score due to the small number of operator risk projects and a lack of major commercial discoveries. Based on the research findings, insights in five aspects have been concluded for overseas risk exploration of Chinese oil companies, including emphasizing exploration benefits, actively operating as a risk exploration project operator, maintaining certain project scale and investment, appropriately controlling project equity, and formulating risk exploration strategies that align with company characteristics. These suggestions are of important practical significance and have long-term strategic value in guiding the development of overseas petroleum exploration strategies and risk exploration policies for Chinese oil companies. Reference | Related Articles | Metrics

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Zhao Xianzheng, Jin Fengming, Chen Changwei, Jiang Wenya, Han Wenzhong, Liu Xuewei, Tang Jizhou, Xu Jing, Chai Gongquan, Zhang Shilin, Sheng Mao, Yin Qiwu Technology and result evaluation of well cementing sliding sleeve single-cluster hole fracturing for continental shale oil reservoir China Petroleum Exploration    2024, 29 (5): 136-147.   DOI: 10.3969/j.issn.1672-7703.2024.05.011 Abstract （283）   HTML    PDF （27129KB）（47）    Knowledge map    Save In Cangdong Sag in Bohai Bay Basin, the continental shale in the second member of Kongdian Formation (Kong 2 member) has great variation in lithology and high heterogeneity, and shale oil production of horizontal wells is significantly different by applying traditional fracturing technologies. In view of these problems, core section with a length of 500 m in Well G108-8 has finely been described, and well cementing sliding sleeve fracturing technological test in Well GY5-1-9H and comparative fracturing simulation experiments between multicluster hole and single-cluster hole have been conducted, which enable to summarize the adaptability, mechanism, and fracturing construction experience of single-cluster fracturing technology for continental shale oil in fault basins. The study results show that the uniformity of fracture initiation by using well cementing sliding sleeve single-cluster hole fracturing has significantly been improved by 1.65-2.04 times compared to bridge plug multi-cluster hole fracturing, overcoming the failure of fracture opening in some clusters due to competitive fracture initiation, as well as problems of casing deformation caused by fluid fingering advance and frac-hit in some clusters. The process of bridge plug pumping and perforation is eliminated when applying well cementing sliding sleeve single-cluster hole fracturing technology, so the construction process is more continuous. A maximum of 11 stages of fracturing construction have continuously been operated in one day, with a construction pressure reduction of 20%–30%, and the number of fracturing trucks decreased from 20 to 9. In Well GY5-1-9H, this technology has been applied to implement single-cluster hole fracturing for 79 stages and 987 m, with a sliding sleeve spacing (cluster hole spacing) of 12.5 m. After fracturing, the cumulative oil production in the first year was 10128 t, and the predicted ultimate recoverable reserves (EUR) were 3.77×10 4 t, setting a record for the highest cumulative oil production and single well EUR of the normalized per kilometer section in shale oil horizontal well in China, which was 1.34-3.15 times that of multi-cluster hole fracturing wells in the same oil enrichment zone; It has also been applied in Shulu Sag in Jizhong Depression, and the steady pressure and production have been achieved in shale oil horizontal wells for over 300 days. This technology delivers useful reference for the development of highly homogeneous continental shale oil in China. Reference | Related Articles | Metrics

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Yang Min, Bao Dian, Zhang Juan, Luo Faqiang, Luo Pandeng, Jiao Baolei Integrated Geological Engineering Practices and Key Technologies for Few Wells and High Production in Shunbei Oil and Gas Field in Tarim Basin China Petroleum Exploration    2024, 29 (3): 45-56.   DOI: 10.3969/j.issn.1672-7703.2024.03.005 Abstract （279）   HTML    PDF （19771KB）（3）    Knowledge map    Save The Shunbei oil and gas field in the Tarim Basin has a burial depth of 7300 to 9000 m. Fracture-cavity reservoirs develops along high and steep strike-slip fault zones which is formed by the fragmentation of brittle strata. The internal heterogeneity of the fault fracture zones is extremely strong, and the fluid properties vary greatly. Facing this type of ultra-deep and complex fault-controlled fracture-cavity oil and gas reservoirs, efficient well formation faces world-class challenges. The cost of a single well is high, and it is difficult to develop profitably. There is no ready-made experience and technology to learn from. Taking project management as the starting point, Shunbei has established unique "five-for-five improvement" geological engineering integrated management model, and has innovatively formed the seven-element key technologies of "fewer wells and higher production". In recent years, the integration of few wells and high production geological engineering has achieved a qualitative leap, and two hundred-million-ton resource positions in the No.four and No.eight fault zones have been implemented, adding 153 million tons of proven oil and 162 billion cubic meters of natural gas. A total of 20 wells have been deployed in the No.four fault zone, and a production capacity of 1.3 million tons of oil equivalent has been built in two years. Compared with the No.1 fault zone developed in 2016, the success rate of high production wells has increased by 35%, the productivity of single wells has increased by 316%, and the proven reserves discovered by single wells have increased by 55%. Efficient exploration and profitable development have been achieved, and its experience has reference significance for the development of other similar types of reservoirs. Reference | Related Articles | Metrics

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Sun Lidong, Yang Liang, Xu Jinshuang, Liu Jiajun, Li Xiaomei, Li Guozheng Geological characteristics and exploration direction of coal gas reservoir in deep layer of Xujiaweizi fault depression China Petroleum Exploration    2024, 29 (4): 73-83.   DOI: 10.3969/j.issn.1672-7703.2024.04.006 Abstract （276）   HTML    PDF （3730KB）（3）    Knowledge map    Save In order to make clarify the favorable exploration of coal gas in deep Xujiaweizi fault depression, we systematical study the geological characteristics of coal gas reservoirs, such as genesis of coal gas, source, reservoir and cap-reservoir combination, by making full use of the data such as seismic, coal and geochemical. The result is that there are two kinds of coal named 1 and 2 coal, which is sediment in shallow lake and delta-front. They are generally reach the high-over-mature stage, with a thickness of 3～10m and average TOC of 29.65%.The coal gas is dominated by methane, and they are all coal-generated gas. The porosity and permeability of coal is 4.74% and 4.42mD. There are several different kinds of reservoir space such as tensile micro-fractures, primary plant tissue pores, pores and mineral pores are developed,which make the coal a favorable reservoir for coal gas in deep layer. There are two kinds of cape and three kinds of cap-reservoir combination in the coal gas, the top and bottom mudstone type and top mud and bottom sand type cap is the favorable gas cap-reservoir combination. The overpressure fluid seal box within the Shahezi Formation is a favorable condition for sealing coal gas at the same time. We selected the 1 coal in Songzhan Sag and 2 coal in Xuxi Sag as the favorable areas for coal gas enrichment area, based on various favorable reservoir-forming conditions, which is also the breakthrough direction of coal gas exploration in the future. Reference | Related Articles | Metrics

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Luo Di, Li Li, Ma Fengyuan, Xie Mingying, Feng Shasha, Weng Heng, Gao Yang, Zhang Shicheng Practice and understanding of geology and engineering integrated reservoir fracturing in offshore low-permeability oilfield: a case study of Lufeng Sag in Pearl River Mouth Basin China Petroleum Exploration    2024, 29 (3): 103-116.   DOI: 10.3969/j.issn.1672-7703.2024.03.010 Abstract （271）   HTML    PDF （13488KB）（5）    Knowledge map    Save Pearl River Mouth Basin is a major area for the accumulation of low-permeability oil and gas reservoirs with huge resources in the offshore China. L44 Oilfield in Lufeng Sag is the first integral low-permeability oilfield that have been fractured and developed in the eastern South China Sea. However, problems such as insufficient scale of reservoir reconstruction and unclear understanding of fracture initiation mechanism occur after fracturing. Based on seismic interpretation, logging and geological data, a geology and engineering integrated modeling method for offshore low-permeability oilfield has been established, which enables to more accurately predict fracture propagation. In addition,3D geomechanical modeling has been conducted and geological/engineering double sweet spots have optimally been selected in the study area.The upper limit of reservoir perforation interval applicable for offshore low-permeability oilfield has been proposed in fracturing design, and the new fracturing scheme design and capacity simulation have been conducted for Well C3, showing a basically consistent production level with the expectation after the secondary fracturing. The study results show that: (1) Given a low displacement, when the length of perforation interval increases from 4 m to 16 m, the fracture length in a stage decreases by 30 m on an average, and the cumulative production capacity of a single well decreases by 88% in the first five years; (2) An increase in the length of perforation interval inhibits the scale of reservoir reconstruction. When the perforation interval is more than 6 m, the scope of reservoir reconstruction greatly decreases; When the perforation interval is less than 6 m, the scope of reservoir reconstruction insignificantly decreases; As a result, the optimal length of perforation interval should be no more than 6 m; (3) Given a perforation interval of less than 6 m, the average reservoir reconstruction volume increases by 10.97% when the construction displacement increases by 1 m 3/min. A higher construction displacement enables to further increase the reservoir reconstruction volume. The geology and engineering integrated modeling method for offshore low-permeability oil fields provides a new idea for the development plan and fracturing scheme design of low-permeability oilfields in the eastern South China Sea, which is beneficial for improving development benefits of oilfields. Reference | Related Articles | Metrics

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Li Chaoliu, Wang Changsheng, Zhang Wenjing, Wang Min, Li Gaoren, Xu Hongjun Logging evaluation method for sweet spots classification of the interlayered type shale oil in continental lake basin: a case study of the seventh member of Yanchang Formation in Wuqi area in Ordos Basin China Petroleum Exploration    2024, 29 (4): 160-169.   DOI: 10.3969/j.issn.1672-7703.2024.04.012 Abstract （269）   HTML    PDF （2029KB）（5）    Knowledge map    Save In view of the difficulty in logging evaluation of the interlayered type shale oil sweet spots, a quantitative evaluation method has been proposed for the coupling relationship of source rock quality parameters, reservoir quality parameters, and their spatial distance, achieving the production capacity classification of the interlayered type shale oil and the determination of the lower limit standard for sweet spots with commercial oil flows after calibrated by well test data, which is reliable confirmed by multiple wells. Based on geochemical experimental data of core samples, a regional model for qualitative TOC calculation has been constructed by using logging data, and the effective source rock interval in the seventh member of Yanchang Formation in Wuqi area has been determined by referring to the relevant standards. The porosity-permeability relationship curve has been used to calculate the reservoir quality factor, and the vertical shortest distance between reservoir interval to be tested and effective source rock has been determined. Finally, a formula for calculating source rock and reservoir coupling coefficient that reflects the coupling relationship between the tested interval and the adjacent main source rock has been established by combining with reservoir quality factor, average TOC and effective source rock thickness. After calibrated by well test results, the lower limit of coupling coefficient in an oilfield or a well area with commercial oil flows has been determined, which enables to evaluate intervals to be tested in new wells and avoid ineffective well testing, improving success rate of unconventional oil and gas well test and providing decision basis for the optimization of capacity construction. Reference | Related Articles | Metrics

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Li Bin, Dong Zhenguo, Luo Qun Research and application of integrated well drilling technology for shale gas exploration in Baojing block, Hunan Province China Petroleum Exploration    2024, 29 (6): 144-156.   DOI: 10.3969/j.issn.1672-7703.2024.06.011 Abstract （267）   HTML    PDF （12398KB）（3）    Knowledge map    Save The geological conditions are complex in Baojing shale gas block, with characteristics of thin reservoir, great burial depth, and high degree of thermal evolution of the Lower Silurian Longmaxi Formation shale. The exploration and development of shale gas are facing great challenges and difficulties, and there is a lack of mature experience to learn from. Therefore, targeting at the goal of speed and efficiency improvement, the exploration mode of “three wells in one” has been applied, and research and practice of integrated well drilling technology have actively been conducted as follows: (1) Well location deployment. On the basis of seismic data inversion, seismic reservoir prediction and gas content detection are conducted. The vertical well is first drilled to obtain reservoir parameters and delineate favorable areas, and then the horizontal well is drilled to evaluate the shale gas production capacity. (2) Geological guidance model establishment. The cross well seismic and logging data are used to establish a geological guidance model before drilling, and then A-B marker bed is used to guide the bit drilling. (3) Implementation of integrated drilling. The upper well section is drilled by downhole screw drill tool to achieve the accurate control of wellbore trajectory. The rotary steering drilling system is applied to drill through the lower well section, and the interactive measurement and control technology is used to monitor the cutting of formation by the drill bit in real time, so as to ensure accurate guidance in the target window. The results show that the integrated well drilling technology enables to improve the drilling rate and accurately obtain formation geological parameters, which is conducive to reservoir evaluation, with a drilling rate of 3.81 m/h and a reservoir penetration rate of 90.68%. The implementation of “three wells in one” exploration mode accelarates the process of shale gas exploration and development. The integrated well drilling technology promotes the shale gas exploration progress in complex structural zone, achieves the low-cost and high-efficiency shale gas development, and provides a reference for shale gas exploration and development in similar areas. Reference | Related Articles | Metrics

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Shu Honglin, Zhang Chao, Cheng Qingsong, Su Zhanhong, Zhang Hanbing, Guo Ning, Meng Yang Geological characteristics and exploration prospects of coal measure gas in the Upper Permian Longtan Formation in Da’an area in Western Chongqing China Petroleum Exploration    2024, 29 (4): 99-110.   DOI: 10.3969/j.issn.1672-7703.2024.04.008 Abstract （259）   HTML    PDF （8976KB）（3）    Knowledge map    Save The coal measure strata in the Upper Permian Longtan Formation serve as important source rock in Sichuan Basin, and good oil and gas displays have commonly been observed during well drilling. However, the previous study work only focused at the level of source rock evaluation, and there was a lack of evaluation on geological conditions of coal measure gas. Based on the comprehensive analysis of core measurement data and well drilling data of Longtan Formation in Da’an area in Western Chongqing, the distribution characteristics, source rock characteristics, reservoir properties, gas bearing property, and preservation conditions have been studied, which support to determine the geological conditions and exploration prospects of coal measure gas in Longtan Formation in Da’an area in Western Chongqing. The study results show that Da’an area was located in the favorable sedimentary zone during the deposition of Longtan Formation coal measure strata,with wide distribution area, thin single layer thickness, and concentrated coal accumulation area; The coal rock is dominated by primary structure, medium-low ash content, and well developed cleats and pores; The coal rock has good gas bearing property, high free gas content,high porosity, high formation pressure and high gas content; The roof and floor of coal rock are mainly composed of mudstone, showing good preservation conditions. The comprehensive evaluation indicates that the coal measure reservoir in Longtan Formation in Da’an area has good porosity and permeability, high gas content, and moderate burial depth, which shows great exploration prospects. Reference | Related Articles | Metrics

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Yang Yong, Zhang Shiming, Lv Qi, Li Weizhong, Jiang Long, Liu Zupeng, Lv Jing, Ren Minhua, Lu Guang Research and practice of stereoscopic evaluation of shale oil in the fourth-third member of the Paleogene Shahejie Formation in Jiyang Depression China Petroleum Exploration    2024, 29 (3): 31-44.   DOI: 10.3969/j.issn.1672-7703.2024.03.004 Abstract （256）   HTML    PDF （9031KB）（5）    Knowledge map    Save Jiyang Depression is a typical continental fault basin in eastern China. A set of thick medium-low maturity shale oil has been identified in the fourth-third member of the Paleogene Shahejie Formation, with resources of more than 100×10 8 t, which is being evaluated and tested at present, showing broad exploration and development prospects. Based on the characteristics of complex lithofacies, diverse reservoir spaces, high heterogeneity, and large source rock thickness of continental shale oil, seismic data, mud logging, wireline logging, coring, and laboratory test data are combined to conduct “four-property” evaluation of source rock, including favorable lithofacies, reservoir physical properties, oil-bearing property, movability, and fracability. The deployment of appraisal wells and pilot tests of well group enable to develop an evaluation technology with the core of stereoscopic sweet spot evaluation, stereoscopic well network optimization, and stereoscopic horizontal well fracturing, and resource potential and technological adaptability have been determined, which provide important support for optimally selecting production zone and achieving large-scale development and production capacity construction. The stereoscopic evaluation tests have been conducted in Boxing, Niuzhuang, and Minfeng areas, confirming the reliability of sweet spot evaluation standards, rationality of well spacing and layer spacing, and adaptability of fracturing technology, and helping to build the first shale oil pilot test well group of Sinopec with a level of 10×10 4 t, which effectively support the high-efficiency construction of national shale oil demonstration zone in Jiyang continental fault lake basin. Reference | Related Articles | Metrics

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Wu Xinsong, Guo Yuling, Li Meng A new method for the prediction of oil and gas reserve growth based on time series of drilling effectiveness China Petroleum Exploration    2024, 29 (5): 148-155.   DOI: 10.3969/j.issn.1672-7703.2024.05.012 Abstract （254）   HTML    PDF （842KB）（48）    Knowledge map    Save The scientific prediction of growth potential of oil and gas reserves is an important prerequisite and foundation for conducting exploration planning and deployment of oil companies. However, all of the commonly used methods have certain deficiencies in predicting oil and gas reserve growth. For example, the prediction methods based on reserve upgrading often have inadequate conditions for application in areas with low level of exploration; The prediction methods based on extrapolation of exploration results lack the concept of time series, so they are difficult to reveal the change rules of oil and gas reserves with time duration. The prediction methods based on life cycles have no connection with exploration workload, so they are difficult to play an effective guiding role in exploration planning and deployment. By properly integrating the petroleum exploration results and time series in this study, a new reserve growth prediction method based on time series of drilling effectiveness has been proposed, and a highly operational modeling and prediction process have been established. In addition, selection strategies for the targeted models in various reserve increase stages have been put forward. The practical application shows that this prediction method is of great significance in revealing oil and gas reserves discovery rules, evaluating the potential of reserve growth, and guiding the exploration planning and deployment in the exploration block. Reference | Related Articles | Metrics

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Chen Xuan, Zhang Hua, Lin Lin, Liu Juntian, Gou Hongguang, Li Xinning, Cheng Yi, You Fan Geological characteristics and exploration potential of deep coal measure gas in Xishanyao Formation in Taibei Sag, Turpan-Hami Basin China Petroleum Exploration    2024, 29 (4): 45-60.   DOI: 10.3969/j.issn.1672-7703.2024.04.004 Abstract （251）   HTML    PDF （3234KB）（4）    Knowledge map    Save The deep coal measure gas is a new field of petroleum exploration in Turpan-Hami Basin, but the study level is relatively low. Based on coal rock testing and basic geological data, the distribution, coal quality, reservoir properties, macro and micro coal petrology, gas source,and isothermal adsorption characteristics of coal seams in the Middle Jurassic Xishanyao Formation in Taibei Sag in Turpan-Hami Basin have systematically been studied, which support to identify the gas-bearing property of coal measure reservoir and its influencing factors,propose accumulation and enrichment conditions for the deep coal measure gas, establish enrichment and accumulation patterns, and predict exploration potential in Taibei Sag. The results show that: (1) The coal seams in the deep Jurassic Xishanyao Formation in Taibei Sag have a wide distribution area and a great thickness, which are characterized by medium-low rank, primary structure, well-developed cleavages, low ash content, low water cut, and rich vitrinite. (2) The coal reservoir has high porosity and permeability, which is insignificantly affected by burial depth. The gas logging anomalies are common in coal seam interval, and the reservoir has moderate-good adsorption capacity, showing characteristics of coexistence of free gas and adsorbed gas, rapid gas breakthrough during trial production, and complete gas compositions.(3) After hydrocarbon supply and charging in coal measure strata in Taibei Sag, two hydrocarbon accumulation patterns were formed, i.e.,adjustment type in forward structural zone, and self-generation and self-storage type in slope and subsag areas. (4) There are abundant coal measure gas resources in Taibei Sag, with resource volume of nearly 3×10 12 m 3 of the main coal seams in Xishanyao Formation. Based on the comprehensive evaluation of coal measure gas resource abundance, coal seam thickness, gas content, and preservation conditions, Wenjisang Structural Zone and Xiaocaohu South Slope are favorable areas for deep coal measure gas exploration. Reference | Related Articles | Metrics

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Yang Yanhui, Zhang Pengbao, Liu Zhong, Zhang Yongping, Xiao Yuhang, Han Feng, Zhao Liangyan, Wang Xiaoxuan, Yang Zhoupeng, Bai Xiaobin, Liu Zhenxing, Hu Jiahua Gas accumulation characteristics of high-rank coal in deep formations in the southern Qinshui Basin China Petroleum Exploration    2024, 29 (5): 106-119.   DOI: 10.3969/j.issn.1672-7703.2024.05.009 Abstract （250）   HTML    PDF （68640KB）（45）    Knowledge map    Save A shallow–medium coalbed methane (CBM) field has been established in the southern Qinshui Basin with an annual production capacity of 2.6×10 8 m 3. However, the exploration of deep CBM is at a low level, and there is insufficient geological understanding. By using drilling, lab test, and trial production data of exploration wells in the study area, accumulation characteristics of deep CBM have been analyzed from four aspects, i.e., coal reservoir characteristics, thermal evolution and gas-bearing property, preservation conditions, and temperaturepressure characteristics. The study results show that: (1) The No.3 coal seam is consistent, with a total thickness of 4.0-7.3 m, which has the favorable conditions of high vitrinite content, low ash content, and well-developed fissures; (2) R o of the No.3 coal ranges in 2.41%–3.03%, showing a high-rank coal, which has strong adsorption capacity, with an adsorbed gas content of higher than 20 m 3/t; (3) The salinity of the produced water from No.3 coal is greater than 4000 mg/L, showing a NaHCO 3 water type, and it is in a weak radial flow environment. The deep CBM reservoir has the characteristics of slightly low temperature and low pressure, indicating that it has suffered certain damage, which insignificantly affected the adsorbed gas, but was not conducive to the accumulation of free gas. The conclusion suggests that the accumulation conditions for deep CBM in the study area were more favorable than the shallow–medium CBM that has already been appraised and developed in the slope zone. The estimated CBM resources of the deep No.3 coal are 1200×10 8 m 3, indicating good potential for CBM exploration and development. Reference | Related Articles | Metrics

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Shi Yujiang, Gan Renzhong, Lin Jingqi, Cao Zhifeng, Wang Xianhu, Zhang Hao, Zhang Kai, Yuan Long, Zhou Jufeng, Duan qingqing, Zhao hongyi, Xu Rui Mechanism and potential of high-yield oil and gas production in the ultra-deep tight clastic reservoirs in the southern margin of Junggar Basin China Petroleum Exploration    2025, 30 (1): 79-94.   DOI: 10.3969/j.issn.1672-7703.2025.01.007 Abstract （248）   HTML       Knowledge map    Save In the thrust belt of the southern margin of Junggar Basin, the high-yield oil and gas production has successively been obtained in the deep to ultra-deep tight clastic reservoirs in the lower combination, with effective reservoirs and production capacity closely related to formation overpressure intensity. In order to clarify the mechanism of formation overpressure on high-quality reservoir and production capacity, the influence of formation overpressure on reservoir pore structure, permeability, oil and gas saturation, reservoir permeability,and production pressure difference is studied by integrating with previous studies and using geological, logging, drilling, well testing and petrophysical experimental data. In addition, the petrophysical experiments are conducted with the simulated dynamic pore pressure in reservoir formation conditions. The study results show that the highly–extremely over-pressured strata were widely developed in the study area, with intergranular pores retained, overpressure fractures developed, and reservoir “storage pores” and “connection pores” interconnected with each other, forming a high-quality reservoir with double porosity structure of matrix pores and fractures, which was conducive to the formation of high oil and gas saturation. The pore structure of the reservoir was controlled by lithology and overpressure intensity. Formation overpressure had little influence on the absolute reservoir porosity, but had great influence on permeability. When the pore pressure reached a critical value, the permeability increased abnormally, which was conducive to fracture initiation, enhancement of fluid flow capacity,and formation of high-yield oil and gas layers. Therefore, the formation overpressure showed mechanism of “retaining pores, increasing permeability and enhancing saturation”, and the overpressure intensity was the key factor for forming high-quality reservoir and achieving high-yield oil and gas production, as well as the basis for realizing high-yield and steady oil and gas production. The study results indicate that the favorable exploration area of deep to ultra-deep reservoirs in the southern margin of Junggar Basin is the effective traps with formation pressure coefficient of higher than 2.0. Reference | Related Articles | Metrics

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Zhang Wei, Zhou Jian, Zhang Hua, Bi Peidong, Wang Qiuxia, Zhang Hong, Han Xiaodong Mechanism of hydraulic dilation, pressure reduction, and enhanced liquid injection in heavy oil cyclic steam stimulated wells and field practice in Bohai Oilfield China Petroleum Exploration    2024, 29 (5): 156-162.   DOI: 10.3969/j.issn.1672-7703.2024.05.013 Abstract （246）   HTML    PDF （3617KB）（45）    Knowledge map    Save In the process of thermal recovery of heavy oil in Bohai Oilfield, cyclic steam stimulated wells often face problems of difficult steam injection due to poor reservoir physical properties or blockage of the circumferential borehole. Hydraulic dilation, an innovative technology,effectively solves the problems of short effective period and high operational costs by applying conventional well stimulation methods.However, there are few experimental studies on the characteristics of reservoir hydraulic dilation, especially those considering the initial cyclic steam stimulation stage or the true triaxial stress field in actual formation conditions. Taking Bohai L heavy oilfield as an example, the grain size of core sample has been analyzed and the microscopic physical properties of heavy oil layer before steam injection development have been observed, including the microscopic scanning and energy spectrum analysis. In addition, the mechanical and high-temperature hydraulic dilation features of core samples have been studied in the true triaxial stress conditions. The experimental results indicate that the average grain size of core sample is 225 μm, which shows fine–medium grain size. The microstructure of core sample is relatively loose, and there are asphalt cements among grains. The silicon and carbon contents are the highest in core sample. The shear dilation rapidly occurs in the uniaxial stress of core sample, but the core volume continues to be compressed due to the restriction of horizontal stress in the true triaxial stress conditions, without any dilation, showing low rock strength. In the true triaxial high-temperature hydraulic dilation experiment, the fluid pressure in core sample showed significant fluctuation, which indicated that the internal fractures continued to initiate, develop, and propagate during the hydraulic dilation stage, leading to the volume dilation of core sample, and the core sample still had strong bearing capacity after reaching the fracture pressure. CT scanning showed that the core volume expanded significantly after hydraulic dilation, significant deformation occurred in the horizontal direction, and secondary complex fracture network appeared inside, indicating superior dilation effect. Finally, a field case is studied to demonstrate the good results of hydraulic dilation construction in heavy oil cyclic steam stimulated wells in Bohai Oilfield. The study results provide feasibility analysis for hydraulic dilation and safe connection and high-efficiency development of heavy oil. Reference | Related Articles | Metrics

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Su Dongxu, Zhu Yongcai, Liu Longsong, Qian Haitao, Chen Hailong, Jiang Zhongfa, Zhang Tianhuan Gas accumulation conditions and exploration orientation of the Carboniferous-Permian in West Well Pen 1 Sag and its periphery in Junggar Basin China Petroleum Exploration    2024, 29 (4): 84-98.   DOI: 10.3969/j.issn.1672-7703.2024.04.007 Abstract （244）   HTML    PDF （15967KB）（5）    Knowledge map    Save Recently, major gas discoveries have been made in the near-source lower combination of the Carboniferous-Permian in wells SX16 and SX18 in the peripheral West Well Pen 1 Sag in Junggar Basin, showing prospects of a large gas production area. However, there is a lack of systematic study on gas distribution rule and favorable exploration areas of the Carboniferous-Permian gas reservoirs in the study area, which restricts the understanding of gas accumulation law and exploration deployment in the near future. As a result, by using seismic, logging, core, thin section and geochemical experimental data, hydrocarbon accumulation conditions such as source rock, reservoir and transport system have systematically been analyzed, and the hydrocarbon accumulation patterns of three major oil-bearing layer groups in the Carboniferous-Permian have been established. In addition, the further exploration orientation has been proposed. The study results show that: (1) Two sets of highquality source rocks are observed in Fengcheng Formation and Lower Wuerhe Formation, with large thickness of 80-200 m, burial depth of greater than 7000 m, high thermal evolution degree, and R o of greater than 1.72%, which have reached the stage of large-scale gas generation and have gas source conditions for the formation of large and medium-sized gas fields. (2) Three sets of large-scale reservoirs were developed, providing basis for high-yield gas production. The Carboniferous reservoir is dominated by volcanic rocks, with high-porosity stomatal overflow volcanic rocks and explosive volcanic breccias developed, good physical properties after weathering and fracture transformation,and the maximum porosity of more than 20%; In Fengcheng Formation, the conventional glutenite, unconventional dolomitic tight sandstone, and unconventional dolomitic shale are orderly distributed, with an average porosity of lower than 8% but large distribution area of more than 2600 km 2; The sand bodies in the first member of Upper Wuerhe Formation are overlapped and contiguous in the sag area, forming lithologic trap groups. (3) The stereoscopic transport system was formed by matching of deep and large fault system in the Hercynian and unconformity surface, which was conducive to the large-scale gas accumulation in the lower combination. (4) The three major oil-bearing layers showed different hydrocarbon accumulation patterns, among which the Carboniferous was dominated by “upper source rock and lower reservoir, and a large-span connection of source rock and reservoir”, it was coexistence of unconventional and conventional gas in source rock in Fengcheng Formation, and it was a large-scale stratigraphic-lithologic trap type gas reservoir in Upper Wuerhe Formation. It is concluded that the gas accumulation conditions are good in the Carboniferous-Permian in West Well Pen 1 Sag and its peripheral area, showing great potential for gas exploration. The favorable exploration orientations include the Carboniferous structural gas reservoir near source rock area in the nose uplift zone, the conventional glutenite gas reservoir, unconventional tight gas and shale gas in Fengcheng Formation, and the first member of Upper Wuerhe Formation in the sag area. Reference | Related Articles | Metrics