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Fu Jinhua, Wang Long, Chen Xiu, Liu Jiangyan, Hui Xiao, Cheng Dangxing Progress and prospects of shale oil exploration and development in the seventh member of Yanchang Formation in Ordos Basin China Petroleum Exploration    2023, 28 (5): 1-14.   DOI: 10.3969/j.issn.1672-7703.2023.05.001 Abstract （1363）   HTML    PDF （8745KB）（23）    Knowledge map    Save As an important replacement resource, shale oil is a major exploration field widely concerned at home and abroad. The long-term exploration and development practice enabled to make significant breakthrough and progress in the exploration, development and research of shale oil in the seventh member of Yanchang Formation (Chang 7 member) in Ordos Basin: (1) On the basis of exploration breakthrough in the interlayered type shale oil and discovery of the first integral one-billion-ton level Qingcheng Oilfield, the large-scale and benefit development has been achieved, and a million-ton level national shale oil development demonstration zone has been constructed. (2) In the exploration of the laminated type shale oil, four types of laminated type have been classified of the fine-grained sedimentary complex for the first time, i.e., sandy lamina, tuffaceous lamina, high TOC argillaceous lamina, and medium-low TOC argillaceous lamina. The combination of sandy lamina and medium-low TOC argillaceous lamina is the optimal “sweet spot” interval of the laminated shale oil by evaluating their development scale, reservoir performance, oil-bearing property, movability, and crude oil properties. For the sweet spot interval, new logging evaluation methods such as M- N cross plot are used to finely interpret the complex lithology, and the directional perforation and cross-layer stereoscopic fracturing technology enable to achieve the spatial communication of sweet spots around the wellbore in horizontal section, forming technologies for the effective identification, prediction of sweet spots and reconstruction of the laminated type shale oil, and achieving a major breakthrough in risk exploration, with the primarily submitted predicted shale oil reserves of 2.05×10 8 t. (3) The laminar type shale oil is subdivided into two categories. The medium-high maturity organic shale can be developed by horizontal well, and relatively high TOC (4%-14%) and high S 1 content are key indicators for screening favorable sweet spots. While the medium-low maturity organic shale is the most favorable target for in-situ transformation research. The strategic breakthrough has been made in the exploration of continental shale oil in Chang 7 member in Ordos Basin, which is a milestone in China’s petroleum exploration and development history, but it still faces great challenges. For example, the large-scale and benefit development has been achieved of the interlayered type shale oil, but further research should be conducted on the prediction of sweet spots, production increase and efficiency improvement, and enhanced oil recovery. The laminated type shale oil is facing more challenges and greater difficulty in benefit utilization due to the completely different sedimentary settings, lithologic combination, reservoir space, and engineering quality from the interlayered type shale oil. Therefore, by focusing on the reserve quality and oil movability, hydrocarbon accumulation law should continuously be studied and the research on supporting technology should be strengthened. While for the laminar type shale oil with relative low level of exploration and understanding, the theoretical research and pilot test should steadily be promoted. Reference | Related Articles | Metrics

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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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Wang Haige, Huang Hongchun, Ji Guodong, Chen Changchang, Lv Zehao, Chen Weifeng, Bi Wenxin, Liu Li Progress and challenges of drilling and completion technologies for deep,ultra-deep and horizontal wells of CNPC China Petroleum Exploration    2023, 28 (3): 1-11.   DOI: 10.3969/j.issn.1672-7703.2023.03.001 Abstract （1274）   HTML    PDF （1246KB）（84）    Knowledge map    Save The deep, ultra-deep and unconventional resources have grown to be the major exploration and development fields for increasing reserves and production in China. Since the 13 th Five-Year Plan period, the engineering technology has continuously been researched by focusing on the key exploration and development targets in six basins (including five oil basins and three gas basins) and drilling speed acceleration difficulties, such as high temperature and high pressure formations and narrow fluid density window, and a large number of technical achievements have been obtained. For example, the key drilling and completion technologies for deep, ultra-deep and unconventional horizontal wells have been developed rapidly, forming key technologies with the core of unconventional well structure optimization, safe, highefficiency,optimal and fast drilling, high-temperature resistant drilling fluid, finely pressure-controlling drilling and completion, and expansion pipe, and a number of landmark ultra-deep wells have successfully been drilled; The equipment has been developed such as high-power top drive, integrated geo-steering system, and green economic reservoir reconstruction tool, as well as core additives such as temperature resistance high-performance drilling fluid and high-efficiency leak-proof and plugging materials have been researched, which have accelerated the lowcost,large-scale and cost-effective development of unconventional oil and gas resources. The drilling depth of deep wells exceeds 9000 m, the horizontal section length of horizontal wells is up to 5000 m, and the maximum footage of one trip drilling is 3700 m, with some indicators comparable to those in North America. The research achievements have boosted the discovery and development of large oil and gas fields such as Tarim Fuman, Sichuan Shuangyushi and Daqing Gulong, and provided powerful engineering and technical supports for improving the utilization rate and benefits of resource exploration and development. Associated with the continuous progress of petroleum exploration and development, the engineering geological risks and new challenges faced by drilling operations occur frequently. Therefore, further research is still necessary, including accurate prediction of formation pressure, optimization and expansion of wellbore structure, well trajectory control,high-temperature resistant working fluid system, high-efficiency rock breaking and speed-up tools, as well as integration of geology and engineering, so as to realize the continuous iteration and upgrading of key drilling technologies and equipment, and support the high-efficiency exploration and development of deep, ultra-deep, and unconventional oil and gas resources. Reference | Related Articles | Metrics

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Lei Qun, Weng Dingwei, Cai Bo, He Chunming, Shi Yang, Ma Zeyuan Progress, key challenges and countermeasures of reservoir stimulation technology of PetroChina China Petroleum Exploration    2023, 28 (5): 15-27.   DOI: 10.3969/j.issn.1672-7703.2023.05.002 Abstract （1138）   HTML    PDF （1123KB）（16）    Knowledge map    Save In order to guarantee the policy of national energy resources security and accelerate domestic oil and gas production, confronting growing complex exploration objects, innovation and advance in reservoir stimulation are the most significant drivers for discovering resources and increasing reserves. By comprehensively reviewing the development history of reservoir stimulation and analyzing technical challenges for exploration target characteristics of PetroChina Company Limited (PetroChina), main progress of reservoir stimulation is systematically summarized, including the optimized design of fracture-controlled stimulation to maximize the release of reserves, the increasing operational capability of fracturing equipment, more robust downhole tools, lower cost of fracturing fluid and improved personalization, and the obvious trend of proppant to low-cost and small mesh size. The supporting role of reservoir stimulation for exploration discovery is clarified. A comprehensive analysis of the key problems faced by hydraulic fracturing is conducted in four aspects: i.e., primary elements of fracturing, fracturing design optimization, field operation quality, and technology evolution. Specifically, the countermeasures in four aspects are proposed: (1) igniting innovation of basic research to provide theoretical support for the progress of fracturing technology; (2) promoting the quality of five primary elements to support the high-quality development of reservoir stimulation technology; (3) promoting the precise technical scheme to provide guidance for more efficient exploration and development of oil and gas; (4) increasing the efficiency of technical management to create a new mode of efficient treatment of engineering management. Reference | Related Articles | Metrics

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Wu Yugen, Men Xiangyong, Lou Yu New progress and prospect of coalbed methane exploration and development in China during the 14 th Five-Year Plan period China Petroleum Exploration    2024, 29 (1): 1-13.   DOI: 10.3969/j.issn.1672-7703.2024.01.001 Abstract （920）   HTML    PDF （3914KB）（26）    Knowledge map    Save The development of coalbed methane (CBM) helps to achieve the goal of peak carbon and carbon neutrality as early as possible, and the industrialization of CBM development has basically been achieved in China. However, restricted by theoretical and technological factors, the development scale does not match the abundant resources. Since the 14 th Five-Year Plan period, new progress has been made in CBM exploration and development, including five aspects: (1) The large-scale development of deep CBM has begun in China, and the growth rate of CBM output has significantly accelerated; (2) Major breakthrough has been made the exploration and development of deep CBM, greatly expanding the space for industrial development; (3) Remarkable results have been achieved in reservoir stimulation and reconstruction of difficult to recover resources such as low-efficiency areas and thin coal seams in mature gas fields; (4) Compared with the 13 th Five-Year Plan period, the research focus has shifted from medium-shallow to deep CBM, great innovations have been made in CBM development theory and technology represented by large-scale horizontal well multi-stage fracturing technology in four aspects of geological understanding, drilling and completion, fracturing, and drainage and production, significantly increasing the gas production; (5) The policy environment of CBM industry has continuously been optimized. The preliminary study shows that China has abundant deep CBM resources, and deep CBM resources with a burial depth of greater than 1500 m are more than twice as those with a burial depth of small than 1500 m; The proven CBM reserves in China are dominated by middle-shallow CBM, but the recovery rate is only 7%, indicating considerable remaining resources. In addition, there are abundant CBM resources in thin coal seams in the mature gas fields, which are the realistic replacement resources. Therefore, the major breakthrough of deep CBM and the successful reservoir stimulation and reconstruction in mature gas fields have become the main driving force leading the rapid development of CBM industry, which have shown promising prospects. Based on the research results by several institutions and experts, it is expected that CBM output in China will reach 100×10 8 m 3 in 2025 and 300×10 8 m 3 in 2035. On the other hand, CBM development in China is faced with many challenges. For example, the geological theory and understanding in the new fields of deep CBM and thin coal seams need to be deeply and systematically studied, exploration and development engineering technology for deep CBM is still in the research stage, and the policy support for industrial development still needs improvement. Therefore, it is suggested to strengthen risk CBM exploration and favorable zone selection and evaluation in new fields, strengthen theoretical and technical research on high-efficiency CBM exploration and development, and strengthen policy support and development guidance for CBM industry. Reference | Related Articles | Metrics

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Zhao Wenzhi, Zhu Rukai, Zhang Jingya, Yang Jingru Classification, exploration and development status and development trend of continental shale oil in China China Petroleum Exploration    2023, 28 (4): 1-13.   DOI: 10.3969/j.issn.1672-7703.2023.04.001 Abstract （873）   HTML    PDF （970KB）（19）    Knowledge map    Save By comprehensively analyzing the current classification scheme of shale oil at home and abroad, and comparing the exploration and development history, shale oil reserves and output status, and production performance of horizontal wells in China and the United States, the differences in geological conditions, resource quality, recoverability, economy and scale of shale oil between the two countries are analyzed. It is proposed to define the continental shale oil zones in China by using the nomenclature of “geographical location + shale oil” or “geographical location + stratigraphic unit + shale oil”. Furthermore, the shale oil types are classified according to two levels: Firstly, the shale oil is divided into three types based on the sandstone-to-formation ratio (the ratio of source rock to reservoir) or sedimentary facies zones, namely tight oil type shale oil, transitional type shale oil, and pure shale oil; Then the pure shale oil is further subdivided into medium-high mature shale oil and medium-low mature shale oil, or in another way, it is subdivided into light oil, thin oil, heavy oil, and viscous oil zones based on the maturity or oil properties. For the medium-high mature continental shale oil targets, efforts should be focused on the evaluation of enrichment zones/intervals in high-pressure zones, as well as trial production, and research on optimal production technology before 2025, so as to reduce costs to the maximum extent and improve initial single-well production and cumulative output. It is estimated that the annual shale oil output in China will be 600×104t to 1000×10 4t. During the 2025-2035, technology will be further upgraded and optimized to reduce costs, and the annual shale oil output is expected to be 1200×10 4t to 1500×10 4t, growing to be a major supplement to crude oil production with an annual capacity of 2×10 8t/a. As for medium-low mature shale oil, pilot test on the in-situ conversion of shale oil in Chang 7 3 sub-member in Ordos Basin is focused at present; At around 2030, the critical equipment and core technologies will be localized hopefully, and the large-scale and commercial development of shale oil will be achieved, with an annual shale oil output of ten millions of tons. 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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Yang Yang, Zheng Xingfan, Xiao Yuxiang, Lei Zhengdong, Xing Housong, Xiong Tie, Liu Mingyang, Liu Shujian, Hou Mingqiu, Zhang Yali Progress in exploration and development of high-mature shale oil of PetroChina China Petroleum Exploration    2023, 28 (3): 23-33.   DOI: 10.3969/j.issn.1672-7703.2023.03.003 Abstract （753）   HTML    PDF （909KB）（23）    Knowledge map    Save Shale oil is an important strategic resource to ensure the long-term steady oil production and production growth in China.PetroChina has made significant exploration breakthroughs in Ordos, Junggar, and Songliao basins, and has discovered shale oil with various lithofacies association types. In order to ensure the steady oil production of 2×10 8 ton/a and improve the security of national energy supply,PetroChina strengthened its efforts in shale oil exploration and development in 2021 and achieved progress in four aspects: (1) The large-scale shale oil development has been conducted in Longdong area, and an integral shale oil demonstration zone has been established with a capacity of one million tons; (2) The construction of Xinjiang Jimsar and Daqing Gulong National Continental Shale Oil Demonstration Zones has been promoted, obtaining shale oil production capacity of up to one million tons in Jimsar area and opening a new chapter in pure type shale oil development in Gulong area; (3) Great efforts have continuously been made in new areas, and historic exploration breakthroughs have been achieved in several basins; (4) The theory, technology, and management have continuously been innovated, obtaining significant results in quality and efficiency improvement. On the whole, the exploration and development different types of shale oil are still in different stages, but there is still a gap to achieve the large-scale benefit development. 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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Wang Qinhua, Yang Haijun, Cai Zhenzhong, Li Yong, Yang Xianzhang, Chen Cai, Chen Changchao Exploration breakthrough and significance of Ordovician fault controlled karst hydrocarbon reservoirs of Well Luotan1 in Maigaiti Slope of Tarim Basin China Petroleum Exploration    2024, 29 (2): 1-15.   DOI: 10.3969/j.issn.1672-7703.2024.02.001 Abstract （600）   HTML    PDF （9238KB）（30）    Knowledge map    Save The Luotan1 well in the Maigaiti slope of Tarim Basin has made a new breakthrough in the Ordovician carbonate rocks, marking the first exploration breakthrough of a new type of Ordovician fault controlled karst carbonate reservoirs in the Maigaiti slope and marking the discovery of an important strategic replacement area in the slope area. Based on regional drilling, logging, seismic and other data, a comprehensive analysis of the laboratory data of well Luotan1 is carried out to further understand the reservoir formation conditions of Ordovician carbonate rocks in the Maigaiti slope. The formation of Ordovician carbonate fault controlled karst reservoirs in the Maigaiti slope is mainly related to strike slip fault activity, and is one of the three main reservoir formation models in the Maigaiti slope. At present, it has been discovered that hydrocarbon in the Maigaiti slope comes from the source rocks of the Cambrian Yuertus Formation, and the basement paleostructure controls the sedimentation and distribution of the Lower Cambrian source rocks. The slope area has three stages of hydrocarbon charging and accumulation: the Caledonian, Hercynian-Indosinian, and Himalayan periods. Hydrocarbon source rocks, paleotectonic evolution, and the faults connecting hydrocarbon source rocks control the multi-stage hydrocarbon accumulation. The fault active stages and fault penetrating layers determine the hydrocarbon enrichment layers and reservoir properties. The Maigaiti slope is characterized by well-developed Ordovician strike slip faults, with an extension distance of over 1000km, which control the distribution of fault controlled karst carbonate reservoirs and hydrocarbon reservoirs. It has clear zoning characteristics on the plane, with a large resource scale and strong deployability, demonstrating huge exploration potential. It is an important practical field for large-scale hydrocarbon exploration discovery and strategic succession in the southwestern Tarim Basin. Related Articles | Metrics

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Liu Guoyong, Song Yong, Mao Xinjun, Tang Yong, Guo Xuguang, Wei Yanzhao, Gong Deyu Main strategies and orientations for high-efficiency exploration in Junggar Basin China Petroleum Exploration    2024, 29 (1): 47-64.   DOI: 10.3969/j.issn.1672-7703.2024.01.004 Abstract （566）   HTML    PDF （9200KB）（11）    Knowledge map    Save The petroleum exploration in Junggar Basin has entered a new stage of exploration in hydrocarbon rich sags, which faces new challenges such as increasing burial depth, more scattered and subtle exploration targets, poorer reservoir porosity and permeability, and low upgrade rate and recovery rate of reserves. It is an urgent task to improve exploration effectiveness and achieve benefit development of oil fields. The new round of integrated research and re-understanding of the basin indicates that the spatial distribution of multiple source kitchens in Junggar Basin are complementary, showing “abundant oil and rich gas”, which has broken through the traditional understanding of “abundant oil but less gas” in the basin; There are four types of large-scale effective reservoirs in hydrocarbon rich sags, with orderly distribution in lateral and superposition in vertical direction; Three types of hydrocarbon accumulation systems are identified, such as orderly accumulation of conventional and unconventional oil and gas in source rock, large-scale hydrocarbon accumulation in regressive fan delta facies glutenites above source rock, and stereoscopic hydrocarbon accumulation in medium-shallow fault-sand coupling reservoirs. In combination with the resource characteristics, new geological knowledge, adaptability of exploration and development technologies, and goal of sustainable and benefit development in Junggar Basin, strategies for high-efficiency exploration are proposed, including “simultaneous exploration of oil and gas, emphasis on both conventional and unconventional oil and gas, co-exploration of deep and shallow oil and gas, and reserve increase in multiple fields”, and three major exploration orientations and nine major exploration fields are put forward, so as to support the benefit and sustainable development of the oilfield. Reference | Related Articles | Metrics

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Liu Xiaobing, Dou Lirong Practice and enlightenment of deepwater petroleum exploration of international major oil companies: a case study of Guyana Stabroek block China Petroleum Exploration    2023, 28 (3): 78-89.   DOI: 10.3969/j.issn.1672-7703.2023.03.007 Abstract （560）   HTML    PDF （4964KB）（124）    Knowledge map    Save In recent years, exploration breakthroughs have continuously been obtained in deepwater fields by major international oil companies. Among them, the joint venture company led by ExxonMobil has discovered 31 deepwater oil and gas fields in Stabroek block in Guyana, making it a rising star in the petroleum industry in South America and driving the exploration boom in the peripheral offshore areas. Guyana Basin spans Guyana and Suriname offshore areas. ExxonMobil’s petroleum exploration in Guyana Basin mainly experienced three stages, namely, the advanced layout in Suriname offshore area during the 1957-1982, re-exploration in Guyana Basin and long-term research in Guyana offshore area during the 1999-2015, and a series of discoveries by applying new geological understanding and seismic technologies since 2015. The exploration practice of major international oil companies in Guyana, especially the joint venture company led by ExxonMobil, shows that it is a feasible and typical way to implement risk exploration by conducting comprehensive regional geological study and applying new data to strengthen exploration confidence and introducing partners to share risks and benefits, which provides reference for Chinese oil companies in promoting overseas petroleum exploration business from “going global” to “going better”. 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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Shi Yujiang, Cai Wenyuan, Liu Guoqiang, Yuan Chao, Zhang Wei, Di Shuhua, Li Si, Wang Shaoqing Full diameter core 2D NMR characteristics of pore fluid in shale oil reservoir and evaluation method China Petroleum Exploration    2023, 28 (3): 132-144.   DOI: 10.3969/j.issn.1672-7703.2023.03.011 Abstract （549）   HTML    PDF （7404KB）（27）    Knowledge map    Save How to objectively evaluate the pore fluid in shale oil reservoir and accurately measure and quantitatively characterize parameters such as oil saturation and mobile oil content in shale oil and tight oil reservoirs are key technical problems that need to be solved urgently.The vehicle-mounted mobile full diameter core NMR measurement instrument is firstly introduced in domestic to conduct on-site core testing analysis and shale oil evaluation, which supports to realize the continuous, high-precision, non-destructive and rapid NMR scanning of drilled core on well site, make up for the shortcomings of NMR logging and indoor core experiments, and fill the blank of on-site measurement technology of full diameter shale oil core in China. Based on field core description, other supporting experimental data and well testing verification, the characteristics of 2D NMR T 1- T 2 spectrum of various fluid components are systematically summarized, the change rule of T 1/ T 2 ratio of oil and water fluid signals in pores with different diameters is identified, and the pore fluid component analysis method and identification standard are established by using 2D NMR spectrum characteristics of full diameter core, which support to realize the accurate identification of pore fluid components and quantitative interpretation of fluid saturation of shale oil, tight oil and complex clastic rock reservoirs. The technology of vehicle-mounted mobile full diameter core NMR measurement has played an important role in the exploration and evaluation of Gulong shale oil in Songliao Basin, Chang 7 3 shale oil in Ordos Basin, as well as in Hetao Basin, and has widely been applied in tight oil and gas oilfields in Daqing, Changqing, Xinan, Huabei, and Xinjiang oilfields, in which good results have been achieved. Reference | Related Articles | Metrics

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Zhang Yu, Zhao Peirong, Liu Shilin, Liu Chaoying, Cheng Zhe, Chen Qian, Chen Gang, Zhang Feiyan Main exploration progress and development strategy of Sinopec during the 14 th Five-Year Plan period China Petroleum Exploration    2024, 29 (1): 14-31.   DOI: 10.3969/j.issn.1672-7703.2024.01.002 Abstract （520）   HTML    PDF （18858KB）（6）    Knowledge map    Save A systematic review is conducted on the high-quality exploration activities, theoretical and technological progress, and exploration achievements of Sinopec during the 14 th Five-Year Plan period, and a development strategy is proposed for the future petroleum exploration. Since the 14 th Five-Year Plan period, Sinopec has strengthened its confidence in resource development and vigorously promoted high-quality exploration practices, which support to make significant exploration achievements in fields such as deep carbonate rocks, continental shale oil, deep shale gas, clastic rocks in western regions, subtle oil and gas reservoirs in mature exploration areas, and deep CBM in Tarim, Sichuan, Bohai Bay, Junggar, and Ordos basins, solidifying reserve basis for stable oil output growth and rapid gas output growth. In addition, significant progress has been made in the development and improvement of deep strike-slip fault-controlled fracture-cavity type hydrocarbon accumulation theory, the innovative shale oil reservoir formation, hydrocarbon accumulation and enrichment theory, and the deep understanding of “dual enrichment” of marine shale gas and differential enrichment mechanisms of oil and gas reservoirs in tight clastic rocks. Furthermore, the key exploration and engineering technologies for targets with complex geological and reservoir structural conditions, represented by seismic exploration, well drilling and completion in deep to ultra-deep formations, wireline logging, mud logging and well testing in ultra-deep formation, and horizontal well fracturing, have been researched and developed. Looking ahead, Sinopec has a solid resource foundation in its exploration areas for achieving steady oil output and rapid increase in gas production. The exploration work will focus on three core responsibilities of securing and expanding mining rights areas, achieving exploration breakthroughs, and increasing reserves and resources on a large scale. Guided by deep earth engineering, shale oil and gas demonstration projects, benefit development of tight clastic rock oil and gas reservoirs, and coordination of conventional and unconventional resources, efforts will be strengthened to accelerate the strategic breakthroughs, and establish large-scale reserve increase bases, so as to further consolidate resource foundation for the sustainable development of the upstream. Reference | Related Articles | Metrics

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Wang Qinghua, Yang Haijun, Li Yong, Cai Zhenzhong, Yang Xianzhang, Xu Zhenping, Chen Cai, Sun Chunyan Major breakthrough in the Carboniferous-Permian in Well Qiatan 1 and exploration prospect in the piedmont southwestern Tarim Basin China Petroleum Exploration    2023, 28 (4): 34-45.   DOI: 10.3969/j.issn.1672-7703.2023.04.004 Abstract （508）   HTML    PDF （9925KB）（10）    Knowledge map    Save A major breakthrough has been made in the Carboniferous-Permian carbonate rocks in Well Qiatan 1 in Wuqia structural zone in the West Tianshan Thrust Belt, marking the discovery of a major replacement formation in the piedmont southwestern Tarim Basin. Combined with the regional geological data, studies on field outcrops, drilling, and seismic data, as well as the comprehensive analysis of laboratory experimental and test data in wells Qiatan 1 and Kuntan 1, hydrocarbon accumulation conditions in the Carboniferous-Permian in the piedmont southwestern Tarim Basin are re-recognized. The study results show that a “horseshoe-shaped” platform margin zone was developed in the Late Carboniferous-Early Permian in the piedmont southwestern Tarim Basin, and a favorable high-energy beach sedimentary facies zone was formed in belts, in which source rocks of bay lagoon facies were deposited in the Permian Qipan Formation, with a thickness of up to 500 m, type Ⅰ-Ⅱ organic matter, and high organic matter abundance. Jointly controlled by sedimentary facies and karstification, the fractured-vuggy type carbonate reservoirs were developed in the Late Carboniferous-Early Permian, forming a favorable reservoir and cap rock assemblage with the overlying thick mudstone in the Permian Qipan Formation. As a result, a new hydrocarbon accumulation pattern of “lower source rock and upper reservoir, hydrocarbon transport by fault and near-source accumulation” is established. The comprehensive analysis indicates that the fault anticline traps in the Carboniferous-Permian are distributed in rows and belts, which have the advantage of near-source hydrocarbon accumulation, and a number of favorable exploration targets such as wells Yetan 1 and Abei 1JS are optimally selected after evaluation, showing good exploration prospects, which are expected to be the major replacement field for large-scale gas exploration and discovery. Reference | Related Articles | Metrics

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Fang Rui, Jiang Yuqiang, Yang Changcheng, Wang Zhanlei, Sun Shasha, Zhu Xun, Li Shun, Gu Yifan, Zhou Yadong, Liu Dongxi, Luo Yao, Luo Yuzhuo Geological characteristics of shale oil in the Jurassic Lianggaoshan Formation in Sichuan Basin China Petroleum Exploration    2023, 28 (4): 66-78.   DOI: 10.3969/j.issn.1672-7703.2023.04.007 Abstract （500）   HTML    PDF （9399KB）（53）    Knowledge map    Save In recent years, major breakthroughs have been made in the exploration of the Jurassic lacustrine shale oil in Sichuan Basin, showing great exploration potential. In order to support the further deepening exploration, the field outcrop, logging, well drilling, coring and systematic core sample experimental data are combined to analyze the geochemical characteristics, rock brittleness, pore structure and oil and gas bearing properties of shale with various lithologic combinations in the Jurassic Lianggaoshan Formation, and identify the lithologic combination types of the dominant shale. The results indicate that the lithologic combination of shale interval in Lianggaoshan Formation is classified into three categories and five types, i.e., pure shale combination, shell type shale combination, and siltstone type shale combination; Among the five types of lithologic combinations, shale is in the mature stage, but there are differences in organic matter content, type, and brittle mineral content. The shale of pure shale combination has an average TOC of greater than 1%, Type Ⅱ 1 organic matter, and brittle mineral content of higher than 52%; The organic matter characteristics of the shale of the shell type shale combination are similar to those of the pure shale combination, but the content of brittle minerals is greater than 65%; The shale of the siltstone type shale combination has an average TOC of less than 1%, Type Ⅱ 2 organic matter type, and the brittle mineral content of greater than 65%. The main reservoir space of various combinations is composed of microfractures and inorganic pores (pore diameter of 10-500 nm). The siltstone type shale combination has a larger pore throat and better pore connectivity than the pure shale combination and shell type shale combination. The free hydrocarbon content of the pure shale combination is greater than 1 mg/g, showing good oil-bearing property. OSI of the pure shale combination and the siltstone type shale combination is greater than 100 mg/g of some samples, indicating good oil movability. The comprehensive analysis shows that pure shale combination and siltstone type shale combination are favorable lithologic combination for shale oil exploration. Benefiting from the good fracability, the siltstone type shale combination is the main sweet spot for shale oil exploration in Lianggaoshan Formation. 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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Wang Qinghua, Yang Haijun, Cai Zhenzhong, Yang Xianzhang, Zhang Liang, Jiang Jun, Zhou Lu Major breakthrough and significance of petroleum exploration in Well Tuotan 1 on the south slope of Kuqa Depression, Tarim Basin China Petroleum Exploration    2023, 28 (5): 28-42.   DOI: 10.3969/j.issn.1672-7703.2023.05.003 Abstract （479）   HTML    PDF （23060KB）（8）    Knowledge map    Save A major breakthrough has been made in the Cambrian buried hill dolomite reservoir in Well Tuotan 1 in Wensu-Xiqiu area on the south slope of Kuqa Depression in Tarim Basin, which is of great significance to the exploration of multi-target buried hill on the hydrocarbon facing side on the south slope of Kuqa Depression. Due to the complex geological conditions, there is a lack of clear understanding on hydrocarbon enrichment law, and it is difficult to identify geological structures and characterize traps, which restrict the petroleum exploration in the buried hills in the study area. Based on the systematic analysis of structural features, stratigraphic distribution in buried hill, source rock-reservoir-cap rock assemblage, hydrocarbon transport system, and exploration practice, a new pattern of hydrocarbon accumulation in the buried hill has been established. The Paleozoic structure in Wensu-Xiqiu area is a back thrust structure controlled by the front thrust Shajingzi-Xiqiu Fault and recoil thrust Wushinan Fault, which is further complicated by two secondary back thrust faults F1 and F2, forming three rows of Paleozoic buried hill structures, with the stratigraphic age from old to new from the near fault to the far fault area in each row of structures. Among them, the Cambrian buried hill strata have the largest distribution range in a NEE direction. The buried hill reservoirs are mainly composed of dolomite of restricted platform granular beach facies, and the high-quality fractured-vuggy type dolomite reservoirs are contiguously distributed after reconstructed by multi stage tectonic activities and long-term exposure and erosion. The hydrocarbon accumulation assemblage of the buried hill oil and gas reservoirs is composed of dual hydrocarbon supply by mudstone source rocks in the Triassic Huangshanjie Formation and the Jurassic Chakmak Formation, fractured-vuggy type dolomite reservoir, and cap rock of the overlying Paleogene gypsum salt rock; The hydrocarbon accumulation is characterized by “distant hydrocarbon supply from Kuqa Depression, hydrocarbon transport by unconformity surface, and hydrocarbon enrichment in structures on the hydrocarbon facing side”, with the main hydrocarbon accumulation period in the late Himalayan (4-1Ma). The successful drilling of Well Tuotan 1 has confirmed the huge exploration potential of multi-row and multi-type buried hills in Wensu-Xiqiu area, with the re delineated buried hill trap area of 840km 2, and the discovered oil resources of about 2.0×10 8t and natural gas resources of about 590×10 8m 3, which is expected to be a new strategic replacement area for increasing oil and gas reserves and production. Reference | Related Articles | Metrics

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Zhou Lihong, Chen Changwei, Yang Fei, Cui Yu, Song Shunyao, Guan Quansheng, Zhou Fengchun Research and breakthrough of benefit shale oil development in Cangdong Sag, Bohai Bay Basin China Petroleum Exploration    2023, 28 (4): 24-33.   DOI: 10.3969/j.issn.1672-7703.2023.04.003 Abstract （474）   HTML    PDF （1841KB）（15）    Knowledge map    Save The large-scale and benefit development of shale oil in the second member of Kongdian Formation (Kong 2 member) in Cangdong Sag in Huanghua Depression face multiple challenges, such as evaluation and optimal selection of main production layers of medium-low mature shale oil, stereoscopic development and production of multiple vertical sweet spots, optimal and fast drilling and completion of horizontal section with a length of 2000 m in complex fault blocks, high-efficiency volumetric fracturing of laminated shale reservoir and high-efficiency lifting of shale oil with high viscosity and high wax content. Go through four stages of shale oil exploration, i.e., research, breakthrough in horizontal wells and pilot test of production capacity evaluation, 60% of the horizontal wells in production have a single well EUR of less than 2.0×10 4t, and the low single well oil rate has become a bottleneck problem restricting the benefit development of lacustrine shale oil. By comprehensively analyzing wireline logging, mud logging, fracturing parameters and production data of Kong 2 member shale oil in 47 production wells, the systematic research has been conducted on sweet spot evaluation and optimal selection of sealing box, well pattern deployment, geosteering while drilling, fracturing reconstruction, and production regime for the lacustrine shale oil in complex fault blocks, and three sweet spot layers (C1, C3 and C5) have been identified for benefit shale oil development in Guandong area, with an favorable area of 42-53.3 km 2 and the estimated Class Ⅰ resources of 1.54×10 8t. The pilot test of benefit shale oil development has been conducted on two 10 m-level sweet spot layers (C1③ and C3⑧) in Kong 2 member on No.5 platform in Cangdong Sag, in which the drilling difficulty of long horizontal section by water-based drilling fluids in complex fault blocks has been solved, the high-efficiency fracturing technology for laminated shale oil has been innovated, and permeability improvement, swelling energization and viscosity reduction of miscible fluids have been achieved of the laminated shale reservoir, with the tested single well peak oil output of 39.6-122.3t. As of June 22, 2023, the five pilot wells had been put into production for 174-201 days, and the cumulative oil output was 3.34×10 4t. The predicted cumulative oil output in the first year is 6.5×10 4t, and the average EUR of a single well is 4.11×10 4t, which indicate that the large-scale and benefit development mode of lacustrine shale oil has been established in complex fault blocks. Reference | Related Articles | Metrics

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Zhi Dongming, Li Jianzhong, Yang Fan, Kang Jilun, Zhang Wei, Ma Qiang, Tao Linben Geological characteristics and exploration and development practice of the Permian full oil and gas system in Jimsar Sag, Junggar Basin China Petroleum Exploration    2023, 28 (4): 14-23.   DOI: 10.3969/j.issn.1672-7703.2023.04.002 Abstract （465）   HTML    PDF （12410KB）（21）    Knowledge map    Save Based on the study of source rock, sediment source system, tectonic evolution and dynamic matching relationship between hydrocarbon source and reservoir, the Permian oil and gas bearing system in Jimsar Sag is analyzed in detail. The study results indicate that the Permian in Jimsar Sag has favorable geological conditions for forming full oil and gas system. On the plane, shale oil, tight oil, conventional glutenite oil reservoirs are distributed in sequence from the central to the marginal sag, and tight oil, shale oil, conventional glutenite oil reservoirs are distributed upward around the high-quality source rock in Lucaogou Formation, showing the overall hydrocarbon accumulation characteristics of “full oil and gas system”. Guided by this understanding, breakthroughs have been made in the exploration of three types of oil reservoirs, basically forming a pattern of oil bearing in the whole sag and orderly co-occurrence and superposition of multi-layer and multi type oil reservoirs. By applying the large platform and multi-layer stereoscopic development mode, the exploration idea and technology for maximizing the benefit resource utilization are gradually mature in practice. The detailed analysis of geological characteristics, hydrocarbon accumulation pattern, and exploration and development practice of the Permian full oil and gas system in Jimsar Sag is of great significance for enriching the exploration theory of the full oil and gas system and guiding the exploration and development in similar oil rich sags. Reference | Related Articles | Metrics

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Liu Yuxi, Bai Bin, Cao Jianzhi, Wang Rui, Zhu Rukai, Meng Siwei, Hou Xiulin Differences in geological characteristics and sweet spots evaluation of marine and continental shale oil: a comparative case study between Wolfcamp D shale oil in Permian Basin in north America and Gulong shale oil in Songliao Basin China Petroleum Exploration    2023, 28 (4): 55-65.   DOI: 10.3969/j.issn.1672-7703.2023.04.006 Abstract （453）   HTML    PDF （15150KB）（19）    Knowledge map    Save The global technical recoverable shale oil resources are 2512×10 8 t, and the cumulative crude oil output from shale series has reached up to 3.9×10 8 t in 2021, which has grown to be one of the major fields for global petroleum exploration and development. Based on the geological conditions and sedimentary characteristics, the “sweet spot” reservoir of continental shale oil in China is classified into three categories, i.e., interlayer type, mixed type and shale type, among which the interlayer type and mixed type shale oil are the main targets for global shale oil exploration and development. Recently, breakthrough has been achieved in the exploration of shale type shale oil. However, the sweet spot evaluation urgently needs to be deepened to provide a basis for achieving benefit shale oil development. Therefore, the geological characteristics between the Carboniferous Wolfcamp D marine shale oil in Permian Basin in north America and the Cretaceous Qingshankou Formation Gulong continental shale oil in China are compared, and the key indicators for sweet spot evaluation of shale type shale oil are discussed, so as to provide reference for the exploration and development of continental shale type shale oil in China. The comparative study indicates that the two sets of shales are dominated by felsic shale and clayey shale with high clay minerals and quartz contents, and show similar geological characteristics of formation overpressure, relatively light oil quality and high brittle mineral content; The reservoir space of Gulong shale oil is dominated by composite organic matter pores and bedding joints related to a large number of clay minerals, showing better connectivity than Wolfcamp D shale oil but slightly poorer organic carbon abundance. The geological sweet spot of Wolfcamp D shale includes organic-rich clayey shale and siliceous shale, while the engineering sweet spot is the organic-rich siliceous shale based on the fracturing results. Similarly, the geological sweet spot of Gulong continental shale oil includes organic-rich clayey shale and felsic shale by using evaluation indicator of retained hydrocarbon, and the engineering sweet spot is the silicic felsic shale. 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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He Xiao, Liang Feng, Li Hai, Zheng Majia, Zhao Qun, Liu Yong, Liu Wenping Breakthrough and enrichment mode of marine shale gas in the Lower Cambrian Qiongzhusi Formation in high-yield wells in Sichuan Basin China Petroleum Exploration    2024, 29 (1): 142-155.   DOI: 10.3969/j.issn.1672-7703.2024.01.011 Abstract （445）   HTML    PDF （10131KB）（10）    Knowledge map    Save Small progress has been made in the exploration and development of shale gas in the Lower Cambrian Qiongzhusi Formation over the years. The high-yield gas flow in Well Zi 201 has greatly increased confidence in the large-scale and commercial development of shale gas in Qiongzhusi Formation. The different enrichment laws in various areas and layers and the optimal selection of favorable areas are the primary problems to be solved for shale gas development. Based on the analysis of paleontology, sedimentary facies, and reservoirs in 57 wells in Sichuan Basin, the theoretical basis for the deployment of Well Zi 201 and enrichment conditions of shale gas in Qiongzhusi Formation are analyzed in detail, and the exploration and development orientation are pointed out. Firstly, a stratification standard for Qiongzhusi Formation is established. It is clarified that four sets of organic rich shale of deep shelf facies were developed in Qiongzhusi Formation (layers ①, ②, ③, and ④), which were controlled by the development of rift troughs, with the largest shale thickness in the trough. The characteristics of shale reservoirs are analyzed, which indicate that the reservoir pressure, porosity, and gas saturation show an increasing trend from bottom to top, and from the outside to the inside of the rift trough, and reservoir overpressure plays an important role in the preservation of shale pores. On this basis, an overpressure and differential shale gas enrichment mode of “different facies in multiple layers and overpressure pore preservation” in Qiongzhusi Formation has been established, and it is pointed out that the overpressure pore development area (interval) far away from the dispersion pathway is the favorable area (interval) for shale gas enrichment. Finally, the study results indicate that Well Zi 201 and its surrounding areas are the main areas for increasing shale gas reserves and production in the future, with resources of 8.06×10 12m 3. It shows considerable development potential in western Sichuan Basin, with resources of 0.72×10 12m 3. Affected by graphitization and tectonic activities, areas with overpressure pore development far from weathered crust and surface outcrops are favorable for shale gas exploration in Changning in southern Sichuan Basin and northern Guizhou Province. Reference | Related Articles | Metrics

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Li Shixiang, Guo Qiheng, Pan Songqi, Zhou Xinping, Guo Ruiliang Influence of intrasource micro-migration of hydrocarbons on the differential enrichment of laminated type shale oil: a case study of the third sub-member of the seventh member of the Triassic Yanchang Formation in Ordos Basin China Petroleum Exploration    2023, 28 (4): 46-54.   DOI: 10.3969/j.issn.1672-7703.2023.04.005 Abstract （444）   HTML    PDF （8261KB）（18）    Knowledge map    Save Influenced by multi type and high density laminae of continental shale, the differential intrasource micro-migration of hydrocarbons is an important factor controlling the oil-bearing property and mobility of the laminated shale with various lithofacies. By taking the systematic shale coring sections in 10 wells in Ordos Basin as the research object and using laboratory experimental results such as XRD, thin section observation, SEM, nitrogen absorption, laser scanning confocal, geochemical test, as well as wireline logging and well testing results,the hydrocarbon micro-migration inside shale section in the third sub-member of the seventh member of the Triassic Yanchang Formation (referred to as Chang 7 3 sub-member) and the mechanism are analyzed. The study results show that the micro-millimeter scale migration generally occurred of crude oil generated by organic-rich laminated shale. Among them, hydrocarbon generation pressurization provided forces for micro-migration; The frequently developed brittle laminae provided a large amount of reservoir space for the micro migrated hydrocarbon; The hydrocarbon generation pressurization fractures, foliation fractures, and micro fractures provided pathways for micro-migration; The different mineral compositions of the laminae resulted in hydrocarbon differentiation. The combination type of laminae and differential micro-migration mechanism determine that the felsic laminated shale and tuffaceous laminated shale have relatively good oil-bearing property and mobility, which are the main lithofacies types for risk exploration of medium-high maturity laminated type shale oil. The commercial oil flow of more than 10 t/d was obtained in pilot test of Chang 7 3 sub-member shale in seven vertical wells, confirming that shale section in Chang7 3 sub member has good oil-bearing property, and there is a high potential of production increase by horizontal well development, which is expected to be a replacement field for reserve and production increase of shale oil in Ordos Basin. 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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Ni Xinfeng, Liu Junping, Xiang Fengyun, Zhang Ying, Guo Mozhen, Wang Xiaoxing, Wang Xia Competitive transfer reform of oil and gas exploration rights in China and innovative practice of oil and gas enterprises China Petroleum Exploration    2023, 28 (6): 25-36.   DOI: 10.3969/j.issn.1672-7703.2023.06.004 Abstract （427）   HTML    PDF （692KB）（6）    Knowledge map    Save In recent years, the reform of national oil and gas market system has continuously been deepened, and competitive transfer has become the main method to acquire new exploration rights. Since the implementation of the “Opinions on Several Issues Concerning the Promotion of Mineral Resources Management Reform (Trial)” (Natural Resources Regulation (2019) No. 7 ), the government has listed and transferred 66 oil and gas exploration rights for 14 rounds, with an area of 4.19×10 4km 2 and a total transaction price of 9.316 billion RMB. Based on the review of the reform process of national mineral resources management, the characteristics of the reform of exploration rights transfer system in different stages, the innovative measures of oil and gas enterprises to actively participate in the reform, and the exploration practice in the competitive transferred blocks are systematically studied. The results show that: (1) The reform of exploration rights transfer system is divided into three stages, i.e., pilot oil and gas reform, issuance of competitive transfer policy, and full implementation of competitive transfer, showing specified characteristics in each stage. (2) In order to actively respond to the fierce competition, PetroChina and other enterprises have innovated management measures, established rapid response mechanism and management system for the competitive transfer, and formed a set of assessment methods and technical processes for evaluating the block value. (3) Some good results have been achieved in the exploration practice in the transferred blocks. However, except for capacity construction in Wensu block by Zhongman Petroleum, the overall oil and gas discovery is few, and most of the blocks have been withdrawn. The competitive transfer of oil and gas exploration rights has played an important role in promoting exploration investment of enterprises and ensuring national energy security, initially forming diversified oil and gas market. In order to realize the high-efficiency utilization of resources, and truly realize the win-win situation of ensuring national energy security and effectively cultivating healthy competition in oil and gas exploration rights market, several suggestions are put forward, including further improving the competitive transfer management system, establishing a national energy security base, and conducting post-evaluation of the transferred blocks. Reference | Related Articles | Metrics

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Xi Shengli, Liu Xinshe, Ren Junfeng, Liu Gang, Zhang Caili, Hui Xiao, Zhao Weibo, Wang Hongwei, Jing Xianghui, Dong Guodong, Wei Jiayi, Li Han New understanding of hydrocarbon accumulation and exploration potential in risk exploration field in Ordos Basin China Petroleum Exploration    2023, 28 (3): 34-48.   DOI: 10.3969/j.issn.1672-7703.2023.03.004 Abstract （426）   HTML    PDF （1753KB）（10）    Knowledge map    Save In recent years, fruitful achievements have been obtained in petroleum exploration in Ordos Basin by innovating geological understanding,highlighting risk exploration, strengthening large-scale exploration, and focusing on benefit exploration, with annual output exceeding 60 million tons of oil equivalent during the 2020-2022, in which risk exploration has played an important role in the exploration of “four new” fields. Based on the previous research results and the deep analysis of hydrocarbon accumulation conditions of the Ordovician subsalt, limestone in the Permian Taiyuan Formation, and shale oil in the seventh member of the Triassic Yanchang Formation (Chang 7 member), the innovative understanding of hydrocarbon accumulation and technical achievements have been formed, including the “new gas-bearing system in the subsalt dolomite mound beach body within source rock”, “sandwiched hydrocarbon accumulation pattern of Taiyuan Formation limestone”, and “sweet spot evaluation standard and special reservoir reconstruction technology for the laminated shale oil in Chang 7 3 sub member”, which have grown to be the replacement fields during the 15 th Five-Year Plan period and in the medium-long term. Meanwhile, by highlighting the exploration concept of “marching towards source rocks,new fields, and deep formations”, the characteristics of hydrocarbon accumulation and exploration potential in zones with low exploration degree are re-recognized according to two levels of key research orientation and zone preparation, and the prospects and orientation of risk exploration fields in the future are proposed. Among them, the key research orientation refers to the zones that have promising signs and great resource potential, mainly including the Ordovician marine shale gas, lower combination of Yanchang Formation, tight gas in coal measures and the Proterozoic Great Wall System; While the zone preparation aims at zones with basic hydrocarbon accumulation conditions, but low research degree and high exploration difficulty, such as the Cambrian in the peripheral of the central paleo uplift, complex structural areas in the western basin margin, and new series of the third-second members of the subsalt Majiagou Formation (Ma 3-Ma 2 members) in the eastern basin. The new geological understanding, achievement summary, and potential analysis of the risk exploration fields will support to achieve the orderly replacement of exploration zones in the basin and play an important guiding role in accelerating the further strategic development of Changqing Oilfield. Reference | Related Articles | Metrics

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Xu Changgui, Zhu Guanghui, Ji Hongquan, Zhu Yanhe, Sun Qiang Exploration progress and reserve increase strategy of onshore natural gas of CNOOC China Petroleum Exploration    2024, 29 (1): 32-46.   DOI: 10.3969/j.issn.1672-7703.2024.01.003 Abstract （424）   HTML    PDF （3098KB）（7）    Knowledge map    Save In order to achieve the rapid development of natural gas industry and increase gas production, CNOOC has gradually increased exploration investment in mining rights areas in Ordos Basin and Qinshui Basin, in which there are multiple types of natural gas including tight gas, CBM, and conventional gas, with gas resources of up to 3×10 12m 3 in the two basins and proven gas geological reserves of 7500×10 8m 3 in high-abundance and structurally simple zones. Based on a comprehensive analysis of resource potential and quality, gas accumulation conditions, and exploration technology, CNOOC has proposed a development strategy of increasing onshore natural gas reserves with a level of trillion cubic meters. The company has clarified the guiding ideology of simultaneous exploration of tight gas and CBM and stereoscopic exploration of multi type gas resources, and determined the deployment strategy of accelerating the exploration of deep CBM and tight gas in the eastern part of Ordos Basin and rapidly promoting the exploration of middle and shallow CBM in Qinshui Basin. Furthermore, the comprehensive analysis of exploration fields, gas accumulation and enrichment laws, and exploration technology research directions enables to clarify the key exploration orientations in the near future. The eastern Ordos Basin is characterized by orderly co-occurrence of full oil and gas system in coal measure strata. As a result, it is necessary to conduct exploration in the full gas accumulation system in coal measure strata, consolidate the material basis for increasing reserves and production, focus on tight gas and deep coalbed methane, research on CBM in thin cool seams, Ordovician conventional natural gas, and bauxite rock gas, and promote the simultaneous exploration and replacement of multi type gas resources by applying exploration and development integration and geology and engineering integration, so as to achieve the exploration and development of full gas accumulation system. In the northern and southern parts of Qinshui Basin, it is necessary to promote the volume fracturing of horizontal wells and production technology tests for middle and shallow CBM and popularize its application, and form complementary economic and effective development with thin CBM, so as to promote the overall increase in CBM reserves and production in Qinshui Basin. The exploration activities in the above key areas will ensure the reserve increase and healthy and stable development of large onshore gas region of CNOOC with a level of trillion cubic meters. Reference | Related Articles | Metrics

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Zhao Zhengwang, Zhang Hang, Zhang Xiaoli, Zeng Lingping Geological characteristics and gas accumulation pattern of tight gas reservoirs in the Upper Triassic Xujiahe Formation in northeastern Sichuan Basin China Petroleum Exploration    2023, 28 (3): 121-131.   DOI: 10.3969/j.issn.1672-7703.2023.03.010 Abstract （421）   HTML    PDF （6597KB）（10）    Knowledge map    Save The exploration of tight gas in the Upper Triassic Xujiahe Formation in Sichuan Basin has always focused in western, central and northern Sichuan Basin, while that in eastern Sichuan Basin has not been attached emphasis due to its complex structural location in ejective fold structural belt, resulting in a low exploration level. In recent years, new breakthroughs have successively been made in the exploration of tight gas in Xujiahe Formation in northeastern Sichuan Basin, and high-yield commercial gas flows have been tested in two wells, which show tight gas potential in Xujiahe Formation in the syncline area in eastern Sichuan Basin. From the perspective of source rock, reservoir and structural conditions, the geological characteristics of tight gas reservoir in Xujiahe Formation in northeastern Sichuan Basin are analyzed,so as to open a new prelude to the tight gas exploration in eastern Sichuan Basin. The study results show that: (1) The hydrocarbon source of Xujiahe Formation gas reservoir in northeastern Sichuan Basin was mainly supplied by source rocks in the Upper Triassic Xujiahe Formation and the Upper Permian Wujiaping Formation, with high intensity of hydrocarbon generation and characteristics of “hydrocarbon supply by dual sources”, which had the material basis for tight gas accumulation; (2) The matrix pores were underdeveloped in Xujiahe Formation reservoir in northeastern Sichuan Basin, and the “fracture-sand body” served as high-quality reservoir. The large-area sand bodies and quasi-continuous fractures in the fifth member of Xujiahe Formation (Xu 5 member) delivered favorable conditions for the formation of large-scale superior “fracture-sand body” reservoir; (3) The gas reservoir in the fifth member of Xujiahe Formation in northeastern Sichuan Basin is characterized by “hydrocarbon supply by dual sources, two-stage gas accumulation and quasi-continuous distribution”, showing superior conditions for gas accumulation. To sum up, Xujiahe Formation in northeastern Sichuan Basin has the conditions for forming large-area and “quasi-continuous” gas reservoir, which has great exploration potential and is of great significance for promoting the exploration of tight gas in the syncline area in the ejective fold structural belt in eastern Sichuan Basin. 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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Wang Yuan, Yang Henglin, Huang Haoyong, Fu Li, Chen Gang, Zhang Heng, Wang Zixin, Guo Kaijie Geomechanical study of deep shale gas and application in Luzhou block, Sichuan Basin China Petroleum Exploration    2023, 28 (5): 68-83.   DOI: 10.3969/j.issn.1672-7703.2023.05.006 Abstract （396）   HTML    PDF （6459KB）（9）    Knowledge map    Save The deep shale gas reservoir (3500-5000m) in the Silurian Longmaxi Formation in Luzhou block in Sichuan Basin is an important replacement field for shale gas development in China. However, the geomechanical properties of reservoir rock and variation in in-situ stress lead to difficulties in the development process, such as the long drilling cycle and large difference in gas rate of a single well. The geomechanical study enables to deepen the understanding of in-situ stress field in the block and provides basis for optimizing well location placement, drilling engineering and fracturing design of horizontal shale gas wells. The acoustic logging, diagnostic fracture injection testing (DFIT), imaging logging, and laboratory stress measurement data are combined to construct a high-precision geomechanical model in Petrel software, which supports to identify the reservoir geomechanical property in the study area, and the application of geomechanical study results in engineering is discussed. The results show that Young’s modulus gradually increases and Poisson’s ratio decreases with the increasing burial depth in Luzhou block. The shale reservoir in Longmaxi Formation is characterized by abnormally high pressure, with pore pressure gradient ranging in 16.7-21.7 kPa/m. The strike-slip type stress regime is dominant in Luzhou block, with an overlying rock pressure gradient of 25.5 kPa/m, a minimum horizontal principal stress gradient ranging in 18.8-24.5 kPa/m, and the average ratio of the maximum horizontal principal stress to the minimum horizontal principal stress of 1.165, and the reservoir horizontal principal stress increases with the increase of Young’s modulus and pore pressure. The geomechanical study results are used to guide the well location placement, optimization of drilling fluid density in drilling engineering, and optimization of fracturing stages and clusters and engineering parameters in fracturing design. For example, the drilling fluid density was optimized to 1.85 g/cm 3 in Well Y65-X, achieving “one trip drilling” of the deviated-horizontal section and a 67% reduction in drilling cycle compared to adjacent wells; The fine fracturing stages and clusters and engineering parameters were optimized for Well Y2-X, and a gas flow rate of 50.69×10 4 m 3/d was tested. The study concludes that the high-precision geomechanical model and achievements enable to effectively improve the drilling operation efficiency and gas flow rate of a single well, and serve for the benefit development. Reference | Related Articles | Metrics

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Zhou Jiuning, Fan Zifei, Bao Yu, Xia Chaohui, Liu Yang, Liang Guangyue Numerical simulation study on SAGD development law of multi-lateral horizontal oil sand wells and evaluation of field development results China Petroleum Exploration    2023, 28 (3): 145-159.   DOI: 10.3969/j.issn.1672-7703.2023.03.012 Abstract （395）   HTML    PDF （7919KB）（14）    Knowledge map    Save Reservoir heterogeneity has a significant impact on the development results of well pair by using steam assisted gravity drainage technology (SAGD). Given the complex reservoir conditions, it is difficult to ensure the uniform development of steam chambers, restricting the development result of a single well pair. In view of the low peak production and low recovery factor of a single well during the development process of oil sand project in Mackay River block in Canada due to the strong reservoir heterogeneity,complex geological conditions, as well as limited and uneven development of steam chambers blocked by mud drape layer, an updip multi-lateral well technology is proposed for various pattern types. The well numerical simulation and dynamic analysis are conducted to explore the methods of steam chamber passing through the mud drape layer and condensate oil passing through the mud drape barrier and flowing into the production wellbore after heating, and accurately recognize the development of steam chambers in multi-lateral wells of various well patterns and evaluate their development results. By constructing a mechanism model, four combination schemes of steam injection wells and production wells are designed and the well simulation is conducted based on the field operating parameters to analyze the production performance, remaining oil distribution, steam chamber development, and recovery rate of horizontal section,and summarize the production law of multi-lateral horizontal wells given the complex reservoir conditions; By conducting analysis of well production performance, the SAGD development results of multi-lateral wells are evaluated, and the differences in development results among various well types are compared. The study results show that a multi-lateral well design enables to significantly increase the effective footage, facilitate the dominant pathway for steam injection and oil drainage, improve the steam injection capacity of well pair, increase the swept volume of the steam chamber, and increase the peak oil rate of the well pair, which solves the problem of barrier by mud drape layer to some extent; In actual field production, multi-lateral production well enables to increase the recovery degree of horizontal sections and improve the development results of single well. However, to some extent, it will increase frac-hit and difficulty in well adjustment, leading to an increase in remaining oil in the lower part of the reservoir. Reference | Related Articles | Metrics

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Ding Feng, Wang Qiaohong, Mao Junli, Wang Shuo, Luo Ling Progress and thoughts on the reform of oil and gas mining rights management in the new era China Petroleum Exploration    2023, 28 (6): 1-7.   DOI: 10.3969/j.issn.1672-7703.2023.06.001 Abstract （386）   HTML    PDF （448KB）（17）    Knowledge map    Save In recent years, the Central Committee of the Communist Party and the State Council of China have successively issued a series of documents, including the reform of the oil and gas system, the reform of the equity fund system, and the reform of the mining rights transfer system, according to which the Ministry of Natural Resources has continuously promoted the reform of oil and gas mining rights management. The significant achievements after implementing reform measures in the new era are summarized, such as opening up the oil and gas exploration and production market, implementing mining rights competitive transfer, and deepening the reform of “optimizing the business environment”, as well as the challenges faced by the current reform work in the transfer, approval, and supervision of mining rights. Furthermore, some opinions and suggestions are provided, including expanding the source of oil and gas blocks, deepening the management mode, establishing a management system in accordance with geological understanding, and promoting comprehensive supervision, so as to further improve the mining right competitive transfer, build scientific mining rights relinquishment system, deepen the reform of “optimizing the business environment” and approval system, enhance the supervision of oil and gas mining rights, accelerate the formation of the new oil and gas exploration and production system dominated by state-owned business and supplemented by other economy sectors, and ensure national energy security. Reference | Related Articles | Metrics

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Yang Yang, Lai Yating, Zhang Xinyi, Gong Xiaoke, Han Jiangchen Characteristics, development risks and effective producing countermeasures of water-bearing tight gas reservoir: a case study of water-bearing area in Sulige Gasfield China Petroleum Exploration    2023, 28 (6): 121-133.   DOI: 10.3969/j.issn.1672-7703.2023.06.014 Abstract （382）   HTML    PDF （1376KB）（10）    Knowledge map    Save Sulige Gasfield is an example of successful tight gas development in China. However, with the progress of gas field development,the problem of water production from gas reservoir is gradually prominent. The water-bearing tight gas reservoirs are developed in the western,northeastern and southwestern parts of Sulige Gasfield, with proven gas reserves of trillions of cubic meters, and the large-scale beneficial gas development is facing great challenges. The analysis shows that the produced formation water is dominated by CaCl 2 type and metamorphic ancient sedimentary water, which is divided into three types of free water, capillary water and bound water. The formation and distribution of water-bearing tight gas reservoirs were affected by several factors, such as gas generation intensity, micro structures, reservoir heterogeneity,and fault system, which were generally developed in areas with low gas generation intensity, while gas enrichment areas were located in local positive micro structures. The evaluation results indicate that are multiple risks in the development of water-bearing tight gas reservoirs,including formation water intrusion, low gas rate of single well, low economic returns, high production cost, and HSE and management. As a result, a series of researches should be strengthened, such as sweet spot area prediction in micro structures, gas/water layer logging interpretation and identification, fine description of effective reservoir space, mixed development well pattern of vertical/deviated well + horizontal well, production measures optimization and low-cost production technology, centralized treatment of produced water and prevention of safety and environmental protection issues, and whole-process water intrusion prevention and control and risk management, so as to realize the successful development of water-bearing tight gas reservoirs. Reference | Related Articles | Metrics

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Jin Fengming, Han Wenzhong, Shi Zhannan, Xu Jing, Song Shunyao, Liu Xuewei, Wang Dong, Guan Quansheng, Sun Biao, Ding Yujiao Enrichment characteristics and key technologies for production and efficiency enhancement of laminated shale oil in Huanghua Depression in Bohai Bay Basin China Petroleum Exploration    2023, 28 (3): 100-120.   DOI: 10.3969/j.issn.1672-7703.2023.03.009 Abstract （378）   HTML    PDF （9131KB）（13）    Knowledge map    Save Huanghua Depression in Bohai Bay Basin has favorable conditions for the formation of laminated shale oil. The three sets of lacustrine laminated shales in the second member of Kongdian Formation (Kong 2 member), third member of Shahejie Formation (Sha 3 member) and the first member of Shahejie Formation (Sha 1 member) have a superimposed area of about 2400km 2, the maximum cumulative thickness of about 1200m,and the calculated shale oil resource volume of 1.2 times that of conventional oil resources, showing great exploration and development potential.However, the benefit development still faces a series of difficulties. By conducting 52 items of joint experiments and tests on 22640 shale samples (701m core) collected from five wells, and analyzing mud logging and wireline logging data in 116 vertical wells, the distribution of the laminated shale oil is identified, which is enriched in (fan) predelta to semi-deep lake subfacies laterally and in the transition zone of the base level T/R cycle vertically in the form of retained oil generated by source rocks in the medium thermal evolution stage. In addition, the quantitative evaluation standard for three types of shale oil favorable areas and enrichment layers is established by eight factors, which effectively guides the “sweet spots” evaluation and selection of the laminated shale oil. Moreover, the field tests of different development schemes, different types of fracturing methods, and different production regimes are conducted in 37 shale oil horizontal wells, which indicate that the optimal horizontal well placement mode can be achieved by using horizontal well spacing of 300m and horizontal section length of 2000m, single-point densely-cutting network volume fracturing enables to greatly improve the production and EUR of single well, as well as the optimally formed “four steps” shale oil well production method, namely,pressure control and water production by small choke, liquid lift/production and blockage prevention by large choke, steady natural flow by medium choke, and long-term production by deeply-set small pump, supports to achieve the high and steady shale oil production. Guided by understanding of enrichment law and key technologies for production and efficiency enhancement of the laminated shale oil, major breakthrough has been made with the highest cumulative oil production of 1×10 4 ton in the first year and EUR of over 3.5×10 4 ton of a single well, achieving the benefit development at an oil price of USD 50 $/barrel, which shows promising development prospect of shale oil in fault basins in eastern China. Reference | Related Articles | Metrics

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Zhang Yunyi Pilot test of cross-layer fracturing in horizontal shale oil well: a case study of Hua H100 platform in Qingcheng Oilfield China Petroleum Exploration    2023, 28 (4): 92-104.   DOI: 10.3969/j.issn.1672-7703.2023.04.009 Abstract （376）   HTML    PDF （3764KB）（7）    Knowledge map    Save A total of 31 horizontal wells have been drilled on Hua H100 platform in Qingcheng Oilfield in Ordos Basin. For the first time, the cross-layer fracturing is tested in four horizontal wells on this platform with low drilling rate of reservoir. Meanwhile, by applying tracer monitoring technology, the engineering feasibility of penetrating mudstone and communicating the adjacent sandstone reservoirs and the effectiveness of flow pathway after fracturing are analyzed, and the production contribution of the cross-layer fracturing stage is evaluated. The pilot test results show that when the distance between the horizontal well trajectory in the non-reservoir interval and the sandstone reservoir is less than 3 m and the clay content is lower than 40%, the cross-layer fracturing engineering is feasible. A total of 14 stages have been tested and good results have been achieved in 12 stages, with a success rate of 85.7%, confirming the feasibility of cross-layer fracturing operation. The tracer detection and interpretation results show that continuous water flowback has been monitored in cross-layer fracturing stages, which indicate that an effective flow pathway has been formed after soaking the well. The varying amounts of oil production in various cross-layer fracturing stages also demonstrate that the sandstone reservoirs have been communicated by cross-layer fractures, with a definite production contribution. Compared with another four offset wells with drilling rate of higher than 80% on the same platform, the cumulative oil production of cross-layer fracturing wells is above the average level. The successful pilot test of Hua H100 platform proves that the cross-layer fracturing is an effective engineering means to increase single well production of horizontal wells with low drilling rate of reservoir. Reference | Related Articles | Metrics