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Petroleum Exploration History and Enlightenment in Tarim Basin TIAN Jun Xinjiang Petroleum Geology    2021, 42 (3): 272-282.   DOI: 10.7657/XJPG20210303 Abstract （941）   HTML （41）    PDF（pc） （2661KB）（728）       Knowledge map    Save After summarizing the petroleum exploration history in the Tarim basin since 1950 from the points of major exploration areas and targets, exploration ideas, geological understandings and exploration technology and achievements, the exploration process for over 70 years in the basin can be divided into 4 stages: (1) Uphill exploration in the piedmont of the margin of the basin from 1950 to 1983; (2) Breakthrough to the cratonic area through conducting 6 times of exploration in the basin, and making many discoveries in cratonic clastic reservoirs from 1984 to 1996; (3) Great breakthrough in Kuqa piedmont area through persisting on “4 equal stresses” and strengthening technical research from 1997 to 2005; (4) Breakthroughs to subsalt thrust belts in the Kuqa foreland basin and to the fractured-vuggy carbonate rocks in ultra-deep exploration areas through focusing on three “battlefields” since 2006. As the first basin targeting ultra-deep exploration in China, it is necessary to summarize the hydrocarbon accumulation laws and exploration experiences. Due to low geothermal gradient and early-deposited effective source rocks, large-scale effective reservoirs may exist and accumulate in ultra-deep layers and large-scale hydrocarbon enrichment zones form. They are potential targets for future exploration, especially in the basin with low geothermal gradient in the central and western parts. The ultra-deep exploration practice in the Tarim basin has proved that persisting on technical research and innovation, conducting 3D seismic survey before drilling wildcat wells, and running integrated exploration and development are successful ways to make fast and large-scale exploration discoveries. Table and Figures | Reference | Related Articles | Metrics

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Petroleum Exploration History and Enlightenment in Jiuquan Basin XIANG Xin, WEI Haoyuan, WEI Deqiang, GAO Xiang, ZHAO Wei, LEI Fuping, XIE Jingyu, REN Xueyao Xinjiang Petroleum Geology    2021, 42 (3): 353-363.   DOI: 10.7657/XJPG20210312 Abstract （820）   HTML （11）    PDF（pc） （2262KB）（372）       Knowledge map    Save Petroleum exploration in Jiuquan basin started in the 1920s. Experienced the exploration process from uplift to depression, fruitful results in petroleum exploration have been achieved. The article reviews the 81-year exploration history in Jiuquan basin, sort out the main idea, technical means, significant discoveries and experience in every stage. Petroleum exploration practices show that the exploration should be foucued on geological research, guided by geological theory and geological understanding, and should be supported by exploration technology. Guided by the theories for exploration of secondary hydrocarbon-bearing structural belts, a number of anticline reservoirs have been discovered. Geology and engineering are closely integrated to form a supporting exploration technology adaptable for Qingxi oilfield, helping Qingxi oilfield make breakthroughs in exploration. After deepening geological understanding and changing exploration ideas three times, a hydrocarbon accumulation model was established for the Ying’er sag and Jiudong oilfield was discovered. New progresses have been made successively due to fine exploration in existing oil blocks after highlighting fine geological research and applying new technologies and methods. Table and Figures | Reference | Related Articles | Metrics

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Petroleum Exploration History and Enlightenment of Biyang Sag and Nanyang Sag in Nanxiang Basin YUAN Yuzhe, LUO Jiaqun, ZHU Yan, LIU Guilan, LI Lei, YU Mengli Xinjiang Petroleum Geology    2021, 42 (3): 364-373.   DOI: 10.7657/XJPG20210313 Abstract （726）   HTML （6）    PDF（pc） （1926KB）（324）       Knowledge map    Save The Nanxiang basin is composed of three swells and four sags. Over more than 40 years of exploration, oil and gas have been discovered in the Biyang sag and Nanyang sag, and fruitful achievements have been obtained. Mainly based on the three peaks of reserves increase in the process of exploring the Biyang sag and the Nanyang sag, this paper divides the basin exploration process into three stages: initial exploration (1970-1983), comprehensive exploration (1984-1999) and detailed exploration (since 2000). After analyzing the major achievements of each stage, it is found that oil and gas enrichment laws in the Biyang sag are more clear and the reservoir types are more representative than those in the Nanyang sag. The Biyang sag can be divided into four important oil and gas enrichment zones: Shuanghe nose-like structure, northern slope zone, southern steep slope zone and around-subsag zone. According to comprehensive analysis of geological characteristics and reservoir-forming conditions, specific exploration ideas, techniques and methods are summarized, including large updip pinch-out sandstone reservoirs in the rifted lacustrine basin, complex fault-block reservoirs in the northern slope zone, small glutenite reservoirs in the southern steep slope zone, and fault-lithologic reservoirs in the around-subsag zone. These results may enlighten future oil and gas exploration. Table and Figures | Reference | Related Articles | Metrics

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Self-Emulsification and Waterflooding Characteristics of Heavy Oil Reservoirs in Wellblock Ji-7 LIU Yanhong, WAN Wensheng, LUO Hongcheng, LI Chen, ZHANG Wu, MA Baojun Xinjiang Petroleum Geology    2021, 42 (6): 696-701.   DOI: 10.7657/XJPG20210607 Abstract （720）   HTML （12）    PDF（pc） （593KB）（305）       Knowledge map    Save With self-emulsification function, the heavy oil reservoir in Wellblock Ji-7 is different from light oil reservoirs and conventional heavy oil reservoirs in waterflooding behaviors at normal temperature, and the waterflooding efficiency is higher in the reservoir. After analyzing the cause of the self-emulsification and the characteristics of emulsion in Wellblock Ji-7, the waterflooding behaviors are defined and it is considered that the main reason for a long-term steady water cut in the middle water-cut period in Wellblock Ji-7 is that the water-to-oil ratio is close to 1 due to the self-emulsification of water-in-oil emulsion. It is further proposed that stabilizing the water-to-oil ratio is one of the most effective measures for waterflooding development in heavy oil reservoirs, and keeping the water-to-oil ratio around 1 can maximize the recovery of heavy oil reservoirs. Table and Figures | Reference | Related Articles | Metrics

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Offshore Petroleum Exploration History and Enlightenment in Beibu Gulf Basin LI Fanyi, ZHANG Houhe, LI Chunrong, ZHANG Wenzhao, HAO Jing, XU Qingmei, YAN Han Xinjiang Petroleum Geology    2021, 42 (3): 337-345.   DOI: 10.7657/XJPG20210310 Abstract （656）   HTML （9）    PDF（pc） （1700KB）（513）       Knowledge map    Save The paper analyzes the historical data of drilling, seismic survey, reserves and production, summarizes the offshore exploration achievements and targets and petroleum geology theory, then divides the offshore exploration process in the Beibu Gulf basin into three stages: (1) Early exploration stage (1960-1995). Drilling results proved that there are good source rocks and source-reservoir-cap assemblages in the Beibu Gulf basin, the basic structural characteristics was understood, and the secondary tectonic units were divided. Early exploration results laid a good foundation for further oil and gas exploration during 1980s when there was a high tide of foreign cooperation. (2) Breakthrough to the Weixinan sag and progressive exploration stage (1995-2010). The discovery and successful evaluation of a number of oilfields represented by Weizhou 12-1 firstly contributed to the cumulative proven geological reserves of oil in the Beibu Gulf basin exceeding 100 million tons. Facing the condition that the Weixinan sag is full of oil but the average size of the oilfields in the sag is relatively small, a progressive exploration strategy was put forward, which broke the bottleneck and realized the upgrading and increase of reserves. (3) Breakthrough to the Wushi sag and exploration into new areas (since 2010). The discovery and successful evaluation of a number of oilfields represented by Wushi 17-2 proved that the Wushi sag is another hydrocarbon-rich sag that has been confirmed by drilling data following the breakthrough of the Weixinan sag. This opened a new prospect in the Beibu Gulf basin. Meanwhile, the exploration to new targets such as buried-hill reservoirs led to the identification of a number of pre-Paleogene carbonate reservoirs which are potential contribution to sustainable development. Table and Figures | Reference | Related Articles | Metrics

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Differences in Microstructures Between Marine and Continental Shales and Its Influences on Shale Reservoir Fracbility WANG Yinggang, SHEN Feng, WU Jinqiao, SUN Xiao, MU Jingfu, TANG Jiren Xinjiang Petroleum Geology    2022, 43 (1): 26-33.   DOI: 10.7657/XJPG20220104 Abstract （633）   HTML （11）    PDF（pc） （7036KB）（116）       Knowledge map    Save Taking the shales of the Longmaxi formation in the Sichuan basin and the Yanchang formation in the Ordos basin as examples, scanning electron microscopy, nuclear magnetic resonance, CT scanning, rock mechanics test and hydraulic fracturing experiments were carried out to investigate the differences in the shale microstructures between marine and continental facies, and then the influence of the differences on shale fracbility was analyzed, and the two kinds of shale were compared by considering fractal geometry and the theory of rock mechanics. According to the research results, the following findings are obtained: a.The continental shale (Yanchang formation) has a high content of clay minerals, accounting for about 45.3%, while the marine shale (Longmaxi formation) is dominated by brittle minerals such as quartz and feldspar, accounting for about 67.9%. b.The porosity of the marine shale is about twice that of the continental shale. c. The proportion of macropores in the marine shale is higher and the pore size distribution is wider, while mesopores and small pores in the continental shale occupy larger space, and natural fractures and beddings are developed. d.The average initial pressure of the continental shale is about 22.52% lower than that of the marine shale, mainly due to low mechanical strength caused by the high clay mineral content in the continental shale, but less effect from pore pressure. e.The major hydraulic fractures induced in the marine shale are transverse cracks that are basically symmetrical along the wellbore, while the natural fractures and beddings in the continental shale can easily capture hydraulic fractures, resulting in shear fractures perpendicular to the major fractures, and the open and connected beddings and weak surfaces are conducive to form a more complex fracture network in the continental shale. f.The three brittleness indicators of the continental shale are all lower than those of the marine shale, but the continental shale has advantages of lower initial pressure, better fracture network and better fracturing potential, so it is inaccurate to evaluate the compressibility of the continental shale by using a brittleness indicator. g.The low porosity, low permeability and high water sensitivity are not conducive to hydraulic fracturing stimulation to the continental shale reservoir. Table and Figures | Reference | Related Articles | Metrics

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Petroleum Exploration History and Enlightenment in Qaidam Basin WEI Xuebin, SHA Wei, SHEN Xiaoshuang, SI Dan, ZHANG Guoqing, REN Shixia, YANG Mei Xinjiang Petroleum Geology    2021, 42 (3): 302-311.   DOI: 10.7657/XJPG20210306 Abstract （587）   HTML （13）    PDF（pc） （2416KB）（430）       Knowledge map    Save This article reviews the arduous and tortuous course of oil and gas exploration in Qaidam basin from 1954 to now, which has obvious stages and complexity. From the 1950s to 1960s limited by technological means, the exploration in the basin focused on surface geological survey and exploration in the shallow strata, and more than ten oil fields such as Lenghu were discovered in shallow strata. From the 1970s to 1980s, simulated seismic exploration was carried out on a large scale, and the technology progress promoted the exploration toward the middle-deep layers and eastern part of the basin. During which, not only the Gasikule oilfield was discovered with the oil reserves of 100 million tons, but the prelude of exploring large gas fields was opened in the eastern part of the basin. In the 1990s, the exploration encountered a bottleneck, so deepening geological research and fine evaluation were performed to increase reserves and production. Entering the 21st century, the exploration has been developing in multiple domains and multiple types, and the theory and technology of oil and gas exploration and development have been advanced for the saline lacustrine basin in the Qinghai-Tibet Plateau, and sustainable breakthroughs in oil and gas exploration and rapid growth in reserves have been achieved. The whole exploration process can be divided into four stages: discovery in shallow strata, breakthrough in deep strata, persistent exploration and rapid development. The paper analyzes 5 successful cases of oil and gas field exploration, which can prove the guiding significance of the innovation of scientific and technical theories, the update of exploration ideas and the progress of exploration technology to the exploration breakthrough. Taking history as a mirror, we hope to give enlightenment to future petroleum exploration and development. Table and Figures | Reference | Related Articles | Metrics

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Practices and Cognitions of Petroleum Exploration in Mesozoic,Ordos Basin LUO Anxiang, YU Jian, LIU Xianyang, JIAO Chuangyun, HAN Tianyou, CHU Meijuan Xinjiang Petroleum Geology    2022, 43 (3): 253-260.   DOI: 10.7657/XJPG20220301 Abstract （561）   HTML （31）    PDF（pc） （1437KB）（400）       Knowledge map    Save The Ordos basin is the second largest sedimentary basin in China with abundant oil and gas resources and broad exploration prospects. Typical low-permeability-tight oil reservoirs are develpoed in the Triassic Yanchang formation in the basin,which are difficult to explore. Through continously geological researches on the Mesozoic oil reservoirs in the Ordos basin over the past 50 years,some theories about hydrocarbon accumulation in Jurassic reservoir groups,in large-scale lithologic reservoirs in inland depression lake basins and in continental shales have been formed. By virtue of three strategic shifts,four conventional hydrocarbon provinces with reserves exceeding 10×108 t and a successive zone with shale oil reserves of 20×108 t have been discovered. The proven oil reserves have increased by an average of over 3×108 t per year for 10 consecutive years. Thus,Changqing oilfield in Ordos basin has become an oil and gas province with the fastest increase in reserves and production in China and contributed 12.5% of China's annual oil production,which provides a reference for the petroleum exploration in other similar basins. Table and Figures | Reference | Related Articles | Metrics

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Micro-Pore Characteristics and Influencing Factors of Fengcheng Formation Shale in Well Maye-1 YANG Fan, MENG Xin, WANG Xianhu, YU Peirong, SHAO Guanghui, CHEN Huohong Xinjiang Petroleum Geology    2022, 43 (1): 1-10.   DOI: 10.7657/XJPG20220101 Abstract （554）   HTML （37）    PDF（pc） （3132KB）（365）       Knowledge map    Save Less researches have been carried out on the microscopic pore characteristics of the Fengcheng formation shale in the Mahu sag. In order to determine the influence of pores on the occurrence and enrichment of shale oil, taking Well Maye-1 in the northwestern slope of the Mahu sag as a case, the characteristics of nano-pores and influencing factors in the continental shale were analyzed through X-ray diffraction, SEM, liquid nitrogen adsorption, high-pressure mercury intrusion, etc. The shale in the Fengcheng formation is mainly composed of felsic rock and carbonate rock. In the two kinds of rocks, the types, shapes and sizes of the pores are almost similar. There are inorganic pores, organic pores and micro-fractures, of which dissolution pores and micro-fractures are dominant. In addition, there are parallel plate-shaped fractures, wedge-shaped pores and ink-bottle-shaped pores. The pores are mainly small ones. The distribution of the pore size shows three peaks and the main peak ranges from 30 nm to 60 nm, and the pore connectivity is poor. The porosity of the felsic rock is higher than that of the carbonate rock, and macro-pores develop better in the felsic rock. So the felsic rock is more favorable for exploration. Quartz, feldspar and dolomite are controlling factors on pore development, and they have a balanced contribution to the pores of various sizes. Clay minerals are favorable for the development of micropores and small pores, but have a weaker impact on mesopores. Organic matter has a little effect on pore development. Both inorganic minerals and organic matter are favorable factors for the increase of shale porosity. Table and Figures | Reference | Related Articles | Metrics

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Petroleum Exploration History and Enlightenment in Pearl River Mouth Basin ZHANG Wenzhao, ZHANG Houhe, LI Chunrong, YAN Han, LI Fanyi, HAO Jing Xinjiang Petroleum Geology    2021, 42 (3): 346-352.   DOI: 10.7657/XJPG20210311 Abstract （553）   HTML （14）    PDF（pc） （1734KB）（436）       Knowledge map    Save Oil and gas exploration in the Pearl River Mouth basin has been going on more than 40 years. Considering the changes of exploration strategy and geological understanding, exploration workload, breakthrough and reserve growth, the exploration process can be divided into three stages: (1) Early exploration stage (1974-1984) aiming at large structures in the uplift belt; (2) Anticline exploration stage (1985-1999) focusing on middle and shallow layers in the hydrocarbon-rich sags; and (3) Composite exploration stage (since 2000) paying same attention to oil and gas, deep-water regions and deep layers. A number of innovative geological understandings, theories and technologies have been formed through exploration practices, such as differential hydrocarbon enrichment and composite accumulation theory, the late-stage hydrocarbon accumulation pattern with multi-source hydrocarbon generation and complex transformation, the recognition of deep-water fan in lowstand system tract, the comprehensive evaluation system of “source-migration-accumulation” and the reservoir forming pattern of “near-source hydrocarbon supply with multiple migration networks”. These understandings have enriched the oil and gas exploration theories, and led to continuous breakthroughs of oil and gas exploration in the Pearl River Mouth basin. Table and Figures | Reference | Related Articles | Metrics

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Petroleum Exploration History and Enlightenment in Bohai Sea HAO Jing, ZHANG Houhe, LI Chunrong, ZHANG Wenzhao, LI Fanyi, YAN Han, XU Qingmei Xinjiang Petroleum Geology    2021, 42 (3): 328-336.   DOI: 10.7657/XJPG20210309 Abstract （533）   HTML （11）    PDF（pc） （1888KB）（347）       Knowledge map    Save The Bohai Sea has experienced more than 50 years of oil and gas exploration. Considering the breakthrough in oil and gas exploration domain, reserves growth, operation mode and other factors, the exploration process in the Bohai Sea can be divided into five stages: (1) Early exploration stage (1965-1979): it was dominated by exploration of bulges and buried hills; (2) Foreign cooperation stage (1980-1994): the exploration in this stage was targeted at the Paleogene; (3) Self-driven cooperation stage (1995-2005): its main exploration target was the Neogene; (4) 3D and multi-layer exploration stage (2006-2015); (5) Fine exploration stage (since 2016). Based on the major exploration achievements and milestone exploration events in all stages, this paper systematically summarizes the important theoretical understandings, including the theory of shallow hydrocarbon migration and accumulation, sand control principle of source-sink coupling in time and space, hydrocarbon accumulation mechanism of superimposed strike-slip fault zones, and the deep gas enrichment mechanism with “two highs and one fineness”. These new theoretical understandings further enrich and widen the oil and gas exploration theories, effectively guide the sustaining oil and gas discoveries in Bohai oilfield and have excellent application prospects. Table and Figures | Reference | Related Articles | Metrics

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Petroleum Exploration History and Enlightenment in the Northern Songliao Basin MENG Qi’an, LI Chunbai, BAI Xuefeng, ZHANG Wenjing, XUE Tao, PENG Jianliang, TANG Zhenguo Xinjiang Petroleum Geology    2021, 42 (3): 264-271.   DOI: 10.7657/XJPG20210302 Abstract （531）   HTML （23）    PDF（pc） （1691KB）（632）       Knowledge map    Save According to the exploration history in the northern Songliao basin, this paper summarizes the research results in different exploration stages and analyzes how the exploration idea in each stage changed and its role to exploring new targets. The Songliao basin went through three stages of oil and gas exploration: exploration of structural oil reservoirs (1955–1985), exploration of lithological oil reservoirs (1986–2010), and exploration of both conventional and unconventional oil and gas reservoirs (since 2011). The enlightment lies in objective geological conditions and the understanding of reservoir forming laws are the foundation for exploration deployment, sustainable theoretical innovation is the guarantee to make breakthroughs to oil and gas exploration, and technological innovation of engineering is the key to keeping steady increase of oil and gas reserves. The mature exploration areas in the basin are still primary exploration targets to discover large and medium-sized oil and gas fields in the future. Table and Figures | Reference | Related Articles | Metrics

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Petroleum Exploration Ideas and Discoveries in Upper Wuerhe Formation, Dongdaohaizi Sag, Junggar Basin LI Yanping, ZOU Hongliang, LI Lei, FU Jiyou, XIA Yu, XIE Junyang Xinjiang Petroleum Geology    2022, 43 (2): 127-134.   DOI: 10.7657/XJPG20220201 Abstract （514）   HTML （31）    PDF（pc） （1730KB）（388）       Knowledge map    Save Dongdaohaizi sag is one of the important hydrocarbon-generating sags in the Junggar basin. Petroleum discoveries have been made in the Jurassic and Cretaceous in the uplift around the sag and in the Permian upper Wuerhe formation within the sag. Focusing on key wells with oil and gas breakthroughs in the upper Wuerhe formation within the sag, and combining with the changes in exploration ideas and theoretical understanding, the exploration of the upper Wuerhe formation in the study area is divided into three stages, namely, source-edge fault block exploration stage, in-sag fault block exploration stage, and above-source lithologic exploration stage. The changes in exploration ideas brought about the discovery of high-yield oil and gas reservoirs in the upper Wuerhe formation on the eastern slope of the sag. Also, insights in three aspects have been gained. First, the source rocks in the Pingdiquan formation have entered the stage of light hydrocarbon generation, contributing to the near-source hydrocarbon accumulation in the upper Wuerhe formation. Second, a large-scale retrograde fan delta sedimentary system is developed in the upper Wuerhe formation, where the fan delta front facies belt superimposed by the thick layers of lowstand system tract(LST) and the thin layers of transgressive system tract(TST) serves as favorable reservoirs, with a distribution area of 3 350 km2. Third, the hydrocarbon accumulation in the upper Wuerhe formation is characterized by sand enrichment in troughs, reserves controlled by facies belts, and production controlled by pores/fractures. Petroleum discoveries are concentrated in the eastern part, while no successful drilling result has been made in the western part of the sag. With these exploration ideas and geological understanding to guide the exploration deployment, there will be new discoveries of oil and gas in the Dongdaohaizi sag. Table and Figures | Reference | Related Articles | Metrics

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Petroleum Exploration History and Enlightenment in Sichuan Basin: A Case Study on Sinopec Exploration Areas HU Dongfeng, WANG Liangjun, HUANG Renchun, PAN Changlin, ZHANG Qingfeng Xinjiang Petroleum Geology    2021, 42 (3): 283-290.   DOI: 10.7657/XJPG20210304 Abstract （508）   HTML （15）    PDF（pc） （1888KB）（571）       Knowledge map    Save After systematically analyzing the petroleum geological theory and exploration results of the Sinopec exploration areas in the Sichuan basin, we divide the exploration history of the Sichuan basin into three stages: exploration for structural oil and gas reservoirs (1953-2000), exploration for lithologic gas reservoirs (2000-2010), and exploration for both conventional and unconventional oil and gas reservoirs ( from 2010 to present). Taking Puguang, Yuanba and Fuling gas fields as cases, which are three most representative large gas fields discovered by Sinopec in the Sichuan basin in recent two decades, we analyze the problems arising in the early exploration stage, summarize the theoretical innovations, changes of idea, exploration discoveries and follow-up plans. Our findings can be a reference for exploration in other areas or basins. Table and Figures | Reference | Related Articles | Metrics

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Exploration History and Enlightenment of Coalbed Methane in Baode Block YANG Xiuchun, MAO Jianshe, LIN Wenji, HAO Shuai, ZHAO Longmei, WANG Yuan, LI Li Xinjiang Petroleum Geology    2021, 42 (3): 381-388.   DOI: 10.7657/XJPG20210315 Abstract （499）   HTML （10）    PDF（pc） （1600KB）（400）       Knowledge map    Save Mainly based on the changes in geological knowledge, technological development, number of drilled wells, exploration results and gas production, this paper divides the CBM exploration process of the Baode Block into four stages: (1) Stage of foreign cooperation on exploration and evaluation: 8+9# coal seams were recovered by drainage in horizontal wells, with large water production and difficulties in drainage and pressure reduction; (2) Stage of production test and evaluation of well groups: 4+5# coal seams and 8+9# coal seams were recovered by drainage in cluster wells, with good effect of gas production by drainage; (3) Pilot test stage with integrated exploration and development: the breakthrough in high-yield was achieved through area depressurization of the optimized well pattern in oil-enriched zones; (4) Large-scale development and rolling expansion and evaluation stage: Large-scale productivity construction in favorable areas and rolling expansion exploration in complex areas have been implemented and an annual output of 5×108 m3 have been achieved. Based on the geological understanding and exploration results, this paper summarizes the origin of low-rank coalbed gas, accumulation mode, and “sweet spot” evaluation and the enlightenment to CBM exploration and production in Baode Block. The accumulation theories such as “thermogenic gas as the main source, biogenic gas as the supplement”, “hydrodynamics-controlled gas, monocline and gentle slope” are proposed, and the evaluation index system of “sweet spot” of low-rank coalbed methane enrichment is established. We hope to provide implications to the exploration of low-rank coalbed methane. Table and Figures | Reference | Related Articles | Metrics

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Well Logging Evaluation of Bauxite Reservoirs in Ordos Basin LIU Die, ZHANG Haitao, YANG Xiaoming, ZHAO Taiping, KOU Xiaopan, ZHU Baoding Xinjiang Petroleum Geology    2022, 43 (3): 261-270.   DOI: 10.7657/XJPG20220302 Abstract （490）   HTML （21）    PDF（pc） （4208KB）（239）       Knowledge map    Save Bauxite gas reservoir is a kind of very rare unconventional gas reservoir recently discovered in the Ordos basin, and well logging evaluation plays an important role in its exploration and development. In the early well logging evaluation, bauxite was considered as the weathering crust caprock, but not as a reservoir, and there was no systematic well logging evaluation method suitable for the exploration and development of bauxite gas reservoirs. Based on the aluminous rocks in Taiyuan formation in the Longdong area, southwestern Ordos basin, the well logging evaluation method for bauxite gas reservoirs was studied from five aspects, that is, qualitative lithology identification, mineral composition, reservoir physical properties, quantitative calculation of gas-bearing properties and systematic summary of imaging model-pore structure characteristics. The well logging response for identifying aluminous rock formations was clarified and the aluminous rock identification chart by acoustic time-gamma ray was established. The porosity-permeability-saturation evaluation model for bauxite gas reservoirs was constructed through petrophysical experiments, and the criteria for identifying bauxite reservoir was proposed by combining micro-resistivity scanning imaging and nuclear magnetic resonance logging data. Finally, a well logging evaluation method for bauxite gas reservoirs was formed. Table and Figures | Reference | Related Articles | Metrics

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Characteristics of Incremental Proven Oil and Natural Gas Geological Reserves in China ZHOU Liming, HAN Zheng, ZHANG Daoyong, REN Jihong, FENG Zhigang, ZHANG Chenshuo Xinjiang Petroleum Geology    2022, 43 (1): 115-121.   DOI: 10.7657/XJPG20220117 Abstract （460）   HTML （21）    PDF（pc） （539KB）（311）       Knowledge map    Save In order to understand the growth trend of proven oil and natural gas geological reserves in China, this paper analyzes the distribution and change of the incremental proven oil and natural gas geological reserves discovered from 2010 to 2019 in China. The results show that the incremental proven oil reserves are mainly distributed in the areas such as Ordos basin, Bohai Bay basin, and Junggar basin, and accumulated in the middle-shallow to middle-deep formations in these basins; the incremental proven natural gas reserves are mainly distributed in the areas such as Ordos basin, Sichuan basin, Tarim basin, and East China Sea Shelf basin, and accumulated in middle-deep to ultra-deep formations; the quality of the incremental oil and gas reserves become worse, the abundance goes lower and the burial depth is deeper and deeper; and incremental proven oil and gas reserves are mainly preserved in lithologic oil and gas reservoirs, unconventional oil and gas reservoirs and deep oil and gas reservoirs. Table and Figures | Reference | Related Articles | Metrics

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Multistage Deformation of Yingjisha Anticline in the Front of Southwestern Tarim Thrust Belt, Northwestern China YANG Geng, CHEN Zhuxin, WANG Xiaobo Xinjiang Petroleum Geology    2021, 42 (6): 656-665.   DOI: 10.7657/XJPG20210602 Abstract （443）   HTML （12）    PDF（pc） （3218KB）（321）       Knowledge map    Save In southwestern Tarim basin in the piedmont of western Kunlun Mountain, there are several thrust belts where multiple oil and gas fields have been found. Based on the fault-related fold theory and drilling and 2D seismic data, the Yingjisha anticline in the piedmont of southwestern Tarim basin is finely interpreted, where shallow detachment layers are discovered in the mudstone and gypsum mudstone of the Miocene Anju’an formation, and several shallow simple fault-bended folds are developed as well. It is concluded that the Yingjisha anticline is composed of shallow, middle-deep and deep structural intervals that are superimposed vertically. A wedge structure which contains multiple imbricate structures of thrust faults are developed in the middle-deep interval. Simple imbricate structures are in the deep interval. The growth strata and structural deformation styles indicated that the shallow structures were formed the earliest, followed by the middle-deep structures, and finally the deep structures. In short, there are multiple stages of episodic thrusts starting from the west Kunlun Mountain toward the Tarim basin, so the thrust structures in southwestern Tarim basin have undergone multiple stages of episodic activities. The structures developed in different periods are superimposed vertically, resulting in the present structural pattern. Table and Figures | Reference | Related Articles | Metrics

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Clay Mineral Compositions and Its Genesis in Lower Permian Fengcheng Formation of Mahu Sag, Junggar Basin ZHOU Xuelei, QI Wen, HUANG Yu, ZHANG Huquan, PAN Shuxin, WU Jia, FANG Peng Xinjiang Petroleum Geology    2022, 43 (1): 34-41.   DOI: 10.7657/XJPG20220105 Abstract （433）   HTML （11）    PDF（pc） （9906KB）（125）       Knowledge map    Save In this study, X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to analyze the composition characteristics and genesis of clay minerals in the source rocks of the Lower Permian Fengcheng formation of the alkaline lacustrine facies in the Mahu sag, Junggar basin. The results show that the smectite and illite/smectite mixed layer has a higher content, but the illite content is lower, showing slow illitization of smectite. Considering the depositional background of the Fengcheng formation, it is concluded that the abnormal transformation of smectite is mainly affected by the volcanic rock, climate and diagenetic fluids in the source area. The intermediate-basic volcanic rock and the dry/wet alternating climate promoted the formation of smectite, while the alkaline water with CO2-3 as the primary anion inhibited the illitization of smectite. Table and Figures | Reference | Related Articles | Metrics

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Progress and Enlightenment of Exploration and Development of Major Shale Oil Zones in the USA LI Qianwen, MA Xiaoxiao, GAO Bo, CHEN Xinjun Xinjiang Petroleum Geology    2021, 42 (5): 630-640.   DOI: 10.7657/XJPG20210518 Abstract （432）   HTML （29）    PDF（pc） （803KB）（444）       Knowledge map    Save We reviewed the geological features, reserves, production, drilling activities and progress of development technology in major shale oil zones in the Permian basin, the Bakken area in the Williston basin and the Eagle Ford area in the Gulf of Mexico basin, analyzed the development trend of shale oil in the USA, and summarized the experience and enlightenment from the USA, with the intent to provide a reference to the development of shale oil in China. The results show that the Permian basin has the highest reserves and production of shale oil in the USA, which is mainly produced from the Spraberry zone and the Wolfcamp zone, and they will also be of great importance in the future. In 2020, influenced by COVID-19, the amount of drilling rigs and the oil production in the three major shale oil zones mentioned above first declined and then increased, and the ultra-low oil prices drove a new round of technological innovation and cost-cutting measures to increase well production in oil companies. By referring to the experiences in shale oil exploration and development in the USA, to develop shale oil in China, priority should be given to highly matured light oil and condensate oil, and the advanced development technologies of condensate oil reservoirs in the USA should be studied and followed. Grading evaluation of sweet spot is the basis of efficient development of shale oil in the USA, and plays a particularly significant role at low oil prices. There is a long way to go to get profitable development of shale oil in China. Technological progress is the key to reducing cost and enhancing profit. Technological researches should be paid attention to in early exploration and development. Life-cycle and geological-engineering integration management is recommended. This may be a new way for efficient shale oil development and rapid cost reduction in China. Table and Figures | Reference | Related Articles | Metrics