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The Semi-Quantitative Analysis of Bio-Precursor Organic Matter Compositions and its Significance of Shale Gas Reservoir from Wufeng-Longmaxi Fm. In Dingshan Area, Sichuan Basin

2022; RELX Group (Netherlands); Linguagem: Inglês

10.2139/ssrn.4089918

1556-5068

Xiaomin Xie, Zhihong Wang, Zhigang Wen, Yaohui Xu, Yan Liu,

Methane Hydrates and Related Phenomena

In order to analyze the OM composition, this study carefully identified the OM types of 66 samples from A well in Dingshan area under microscope, and made effort for the semi-quantitative statistics on the bio-precursor OM. The results showed a well positive relation (R 2 =0.85) between the OM composition obtained under microscope with the TOC content. The OM contained bethic algae debirs, phytoplankton AOM, acritarch, vitrinite-like particles, zooplankton (including graptolite, chitinozoa and others), and solid bitumen which was secondary formation OM. The phytoplankton AOM, graptolite and solid bitumen were dominated in this interval. Solid bitumen (8%~11%) were filled at the bottom of Wufeng formation, which could be one of the reasons for the high shale gas production in the lower part of this shale interval. N 2 adsorption results showed that the micropores and mesopore were dominated in this shale gas system, and pore volumes illustrated better positive relationships with organic matter than minerals, especially AOM content. Thus, both solid bitumen and AOM kerogen were the main sources for shale gas generation in this shale gas system.