Fracture vein characteristics and paleofluid activities in the Lower Cambrian Qiongzhusi shale in the central portion of the Mianyang-Changning intracratonic Sag, Sichuan Basin

Huge and thick black shale was deposited in the Mianyang-Changning intracratonic sag of the Sichuan Basin, which is a favorable target for shale gas exploration in the future. Taking the paleofluid preserved in the Qiongzhusi Formation shale as the research object, based on the petrological and opti...

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Published in地质科技通报 Vol. 42; no. 3; pp. 142 - 152
Main Authors Liqing Chen, Juan Wu, Yifan He, Qianqian Jiang, Wei Wu, Chao Luo, Guozheng Du
Format Journal Article
LanguageChinese
Published Editorial Department of Bulletin of Geological Science and Technology 01.05.2023
Subjects
formation pressure
fracture vein
intracratonic sag
paleofluid
qiongzhusi formation
shale gas
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Summary:Huge and thick black shale was deposited in the Mianyang-Changning intracratonic sag of the Sichuan Basin, which is a favorable target for shale gas exploration in the future. Taking the paleofluid preserved in the Qiongzhusi Formation shale as the research object, based on the petrological and optical characteristics of fracture veins observed in cores and thin sections, the source and origin of the paleofluid were analyzed by carbon and oxygen isotope testing, the formation pressure evolution of shale gas was simulated by using BasinMod software, and the preservation conditions of Qiongzhusi Formation shale gas in the central portion and surrounding areas of the Mianyang-Changning intracratonic sag were discussed. The results show that fracture vein rarely appears in the Qiongzhusi Formation shale of wells GS17 and MX9. While multiple groups of bed-parallel and high-angle fractures appear in Well W201, which are filled with mesocrystalline to coarse crystalline calcite, fibrous calcite, saddle dolomite, bar
ISSN:2096-8523
DOI:10.19509/j.cnki.dzkq.tb20220584