Article
Geosciences, Multidisciplinary
Tianshu Zhang, Suyun Hu, Qingyun Bu, Bin Bai, Shizhen Tao, Yanyan Chen, Zhejun Pan, Senhu Lin, Zhenglian Pang, Wanglin Xu, Miao Yuan, Jianwei Fan, Yuanshi Sun, Xuan Feng
Summary: By analyzing core samples and well logging data, this study proposes a novel method based on parasequence division to predict organic matter enrichment in Chang 7 Shale. It identifies certain shale facies as more favorable for shale oil exploration, providing insights for determining target areas and enhancing inter-well prediction for deep-water shales.
MARINE AND PETROLEUM GEOLOGY
(2021)
Article
Energy & Fuels
Guanping Wang, Qian Zhang, Rukai Zhu, Xuan Tang, Kouqi Liu, Zhijun Jin
Summary: The main pore space in the lacustrine Chang 7 Shale is dominated by macro- and meso-pores, while the pores within organic matter are rarely observed. Quartz promotes the development of macro- and meso-pores, while clay minerals show negative effects on their heterogeneity. A critical maturity point of 0.8% Ro is observed for the change of the pore system, and both fractal dimensions and pore structure proxies show inverse trends before and after this point. These findings contribute to a better understanding of pore system evolution and identification of high-quality reservoirs in lacustrine shales.
GEOENERGY SCIENCE AND ENGINEERING
(2023)
Article
Energy & Fuels
Shutong Li, Yang Wang, Ximeng Wang, Ruiliang Guo
Summary: The pore system and gas adsorption characteristics of mudstones in the Ordos Basin were studied. The results show that the studied mudstones are mainly siliceous rocks with intergranular pores and less developed organic matter pores. Micropores and mesopores are the main pore types, with abundant organic matter pores. The presence of rigid minerals can inhibit the compaction of intergranular pores. Organic matter, clays, and rigid minerals have a limited positive effect on gas adsorption capacity. Methane is mainly stored in micropores.
Article
Energy & Fuels
Juan Teng, Hucheng Deng, Yu Xia, Wenling Chen, Meiyan Fu
Summary: Organic matter composition plays a crucial role in determining the hydrocarbon generation potential of black shales, with significant differences observed in AOM type and content between shales from different regions.
Article
Geochemistry & Geophysics
Wang Zhang, Xinping Liang, Peng Li, Guoheng Liu, Jin Qian
Summary: Significant amounts of unconventional oil and gas resources have been discovered in the Yanchang Formation of Ordos Basin, primarily sourced from the shale layers in Chang 7 and 9 members. The C7-3 submember shale has the highest content of illite/smectite mixed layer and reducing minerals, while the C9 member shale has the highest percentage of quartz and illite. The C7-3 submember shale is characterized by high productivity due to type II1 kerogen, and the C9 member shale exhibits the highest organic thermal maturity.
Article
Geosciences, Multidisciplinary
Xiangzeng Wang, Quansheng Liang, Chao Gao, Pei Xue, Jintao Yin, Shiyan Hao
Summary: This paper systematically studies the main controlling factors of lacustrine shale gas accumulation and the prediction of sweet spots in the Chang 7 Member shale of the Yan'an Formation in the Yan'an area. The study reveals the mechanism of hydrocarbon generation and gas accumulation in this shale, providing theoretical support for the exploration and development of lacustrine shale gas.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Energy & Fuels
Peng Pang, Hui Han, Xiu-Cheng Tan, Shi-Meng Ren, Chen Guo, Lin Xie, Hai-Hua Zhu, Yuan Gao, Yun-Hui Xie, Ling-Li Zheng
Summary: This study quantifies the pore characteristics of various macerals in Chang 7 lacustrine shales. The results show that the organic pores are enriched in Chang 7 shales, mainly round or elliptical in shape, with a wide distribution of pore sizes mainly concentrated in the range of 100-400 nm. The average plane porosity of the organic pores is 10.13%.
Article
Geochemistry & Geophysics
Bojiang Fan, Xinyang Dai, Chi Wang
Summary: This study comprehensively compared and analyzed the geochemical characteristics of desorption gas in the Chang 7 Member shale. The results showed that the shale gas mainly consists of CH4, C2H6, and C3H8. Porosity, permeability, and organic matter content are the main geological factors controlling gas migration and hosting. Shale with higher porosity, good permeability, and lower organic matter content is conducive to gas migration. The sandy laminated shale with a higher gas content may be the sweet spot of shale gas targets.
Article
Engineering, Marine
Zhongying Zhao, Lianhua Hou, Xia Luo, Yaao Chi, Zhenglian Pang, Senhu Lin, Lijun Zhang, Bo Liu
Summary: The reservoir properties of low-medium-maturity shale undergo complex changes during the in situ conversion process, including changes in mineral and maceral composition, pore structure, porosity, and permeability. This study quantitatively characterized these changes and identified mechanisms such as kerogen pyrolysis, clay-mineral transformation, unstable mineral dissolution, and thermal stress.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2023)
Article
Energy & Fuels
Qiulei Guo, Yue Yao, Lianhua Hou, Shuheng Tang, Songqi Pan, Feng Yang
Summary: This study investigates the retention, migration, and accumulation of oil in a lacustrine shale system from the Upper Triassic Yanchang Formation, Ordos Basin. The research findings demonstrate the impact of lithofacies on oil composition and amount stored in the shale systems. Organic-rich shale lithofacies retain a large amount of oil, while thin organic-lean siltstones act as reservoir units for migrated petroleum. The study also reveals the influence of pore structure on oil retention and migration.
INTERNATIONAL JOURNAL OF COAL GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Hao Lu, Qing Li, Dali Yue, Yue Wu, Jian Gao, Shenghe Wu, Wurong Wang, Mingqiang Li, Keqin An
Summary: The heterogeneity of shale pore structure is a crucial factor influencing shale oil exploration and development. Organic-rich laminated shale (ORLS) and organic-poor layered shale (OPLS) exhibit significant differences in pore system heterogeneity. ORLS has higher porosity and permeability compared to OPLS, and its pore system shows wider pore size range and stronger holistic distribution heterogeneity. The volume of micropores and macropores is higher in ORLS, while the surface area and volume of mesopores are lower. The macropore in ORLS displays the most obvious fractal characteristics. The mineral composition, laminae, TOC content, thermal evolution degree, and fluid pathways control the evolution patterns of shale reservoirs. The macropore volume in ORLS is positively correlated with pyrite content, and the development degree of secondary dissolution plays a crucial role in determining the reservoir qualities of ORLS and OPLS.
MARINE AND PETROLEUM GEOLOGY
(2023)
Review
Geosciences, Multidisciplinary
Quanyou Liu, Peng Li, Zhijun Jin, Yuewu Sun, Guang Hu, Dongya Zhu, Zhenkai Huang, Xinping Liang, Rui Zhang, Jiayi Liu
Summary: The study focused on the impact of volcanic activity on paleoproductivity and preservation conditions in lacustrine shale formation. The results indicated that volcanic activity enhanced ancient productivity and promoted organic matter preservation.
SCIENCE CHINA-EARTH SCIENCES
(2022)
Article
Thermodynamics
Haiyan Jiang, Shuai Liu, Jiao Wang, Yuan You, Shibao Yuan
Summary: In this study, the pyrolysis process, mineral composition, and pore structure characteristics of Chang 7 oil shale in the Ordos basin in China were investigated using thermogravimetry, scanning electron microscopy, and oil shale pyrolysis. The results showed that as the temperature increased, the organic matter underwent complete pyrolysis, with the formation of asphaltene at low temperatures (320-450 degrees C) and the generation of lipid compounds through the breaking and recombination of C-H bonds. At medium temperatures (450-600 degrees C), a significant amount of organic matter was pyrolyzed, resulting in the pyrolysis reaction of ester compounds and the dehydrogenation and chain breaking reactions of macromolecular alkanes to form small molecule hydrocarbons and hydrogen. High temperature pyrolysis (600-700 degrees C) led to secondary cracking of organic matter pyrolysis products, dehydrogenation of naphthenic hydrocarbons, and the polymerization of some polycyclic aromatic hydrocarbons to generate colloidal, asphaltene, and oil shale semi-coke. With the increase in temperature, clay minerals were completely pyrolyzed, leading to an increase in the number of micropores and microcracks in oil shale.
Article
Energy & Fuels
Bei Liu, Juan Teng, Chen Li, Baoqing Li, Shizhen Bie, Yinlong Wang
Summary: The pore structure characteristics of lacustrine shales are controlled by different components, including minerals and organic matter. Clay minerals primarily control the mesopore characteristics of the shales and the micropore characteristics of organic-lean shales, while both clay minerals and organic matter control the micropore characteristics of organic-rich samples. The study provides important insights into the compositional control on the pore structure characteristics of lacustrine shales.
Article
Geochemistry & Geophysics
Yan Cao, Hui Han, Shijia Chen, Rui Liu, Jingyue Zhang, Chen Guo, Peng Pang
Summary: The study on the source and reservoir characteristics of Chang 6 tight oil revealed that the porosity of the reservoir ranges from 8% to 14%, with major pore types including residual intergranular pore, secondary intergranular dissolved pore, and intragranular dissolved pore. The results indicate a good storage condition for the Chang 6 reservoir in the Sichuan Basin.
INTERPRETATION-A JOURNAL OF SUBSURFACE CHARACTERIZATION
(2021)
