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Article

Relationship between Organic Geochemistry and Reservoir Characteristics of the Wufeng-Longmaxi Formation Shale in Southeastern Chongqing, SW China

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National and Local Joint Engineering Research Center of Shale Gas Exploration and Development, Chongqing Institute of Geology and Mineral Resources, Chongqing 401120, China
2
Key Laboratory of Shale Gas Exploration, Ministry of Natural Resources, Chongqing Institute of Geology and Mineral Resources, Chongqing 401120, China
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Chongqing Key Laboratory of Complex Oil and Gas Exploration and Development, Chongqing 401331, China
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Chongqing Shale Gas Exploration and Development Company Limited, Chongqing 401121, China
*
Authors to whom correspondence should be addressed.
Academic Editors: Xixin Wang and Sohrab Zendehboudi
Energies 2021, 14(20), 6716; https://doi.org/10.3390/en14206716
Received: 7 September 2021 / Revised: 29 September 2021 / Accepted: 30 September 2021 / Published: 15 October 2021
(This article belongs to the Special Issue Shale Oil and Gas Accumulation Mechanism)
Shale gas accumulates in reservoirs that have favorable characteristics and associated organic geochemistry. The Wufeng-Longmaxi formation of Well Yucan-6 in Southeast Chongqing, SW China was used as a representative example to analyze the organic geochemical and reservoir characteristics of various shale intervals. Total organic carbon (TOC), vitrinite reflectance (Ro), rock pyrolysis, scanning electron microscopy (SEM), and nitrogen adsorption analyses were conducted, and a vertical coupling variation law was established. Results showed the following: the Wufeng-Longmaxi formation shale contains kerogen types I and II2; the average TOC value at the bottom of the formation is 3.04% (and the average value overall is 0.78%); the average Ro value is 1.94%; the organic matter is in a post mature thermal evolutionary stage; the shale minerals are mainly quartz and clay; and the pores are mainly intergranular, intragranular dissolved pores, organic matter pores and micro fractures. In addition, the average specific surface area (BET) of the shale is 5.171 m2/g; micropores account for 4.46% of the total volume; the specific surface area reaches 14.6%; and mesopores and macropores are the main pore spaces. There is a positive correlation between TOC and the quartz content of Wufeng-Longmaxi shale, and porosity is positively correlated with the clay mineral content. It is known that organic pores and the specific area develop more favorably when the clay mineral content is higher because the adsorption capacity is enhanced. In addition, as shale with a high clay mineral content and high TOC content promotes the formation of a large number of nanopores, it has a strong adsorption capacity. Therefore, the most favorable interval for shale gas exploration and development in this well is the shale that has a high TOC content, high clay mineral content, and a suitable quartz content. The findings of this study can help to better identify shale reservoirs and predict the sweet point in shale gas exploration and development. View Full-Text
Keywords: shale gas; nanopores; adsorption capacity; shale intervals; vertical coupling variation law shale gas; nanopores; adsorption capacity; shale intervals; vertical coupling variation law
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MDPI and ACS Style

Wang, S.; Wang, J.; Zhang, Y.; Li, D.; Jiao, W.; Wang, J.; Lei, Z.; Yu, Z.; Zha, X.; Tan, X. Relationship between Organic Geochemistry and Reservoir Characteristics of the Wufeng-Longmaxi Formation Shale in Southeastern Chongqing, SW China. Energies 2021, 14, 6716. https://doi.org/10.3390/en14206716

AMA Style

Wang S, Wang J, Zhang Y, Li D, Jiao W, Wang J, Lei Z, Yu Z, Zha X, Tan X. Relationship between Organic Geochemistry and Reservoir Characteristics of the Wufeng-Longmaxi Formation Shale in Southeastern Chongqing, SW China. Energies. 2021; 14(20):6716. https://doi.org/10.3390/en14206716

Chicago/Turabian Style

Wang, Shengxiu, Jia Wang, Yuelei Zhang, Dahua Li, Weiwei Jiao, Jinxi Wang, Zhian Lei, Zhongqiang Yu, Xiaojun Zha, and Xianfeng Tan. 2021. "Relationship between Organic Geochemistry and Reservoir Characteristics of the Wufeng-Longmaxi Formation Shale in Southeastern Chongqing, SW China" Energies 14, no. 20: 6716. https://doi.org/10.3390/en14206716

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