Gas in place and its controlling factors of deep shale of the Wufeng–Longmaxi Formations in the Dingshan area, Sichuan Basin  

作　　者：Ping GAO Xianming XIAO Dongfeng HU Ruobing LIU Fei LI Qin ZHOU Yidong CAI Tao YUAN Guangming MENG 

机构地区：[1]School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China [2]Sinopec Exploration Branch Company,Chengdu 610041,China [3]State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China

出　　处：《Frontiers of Earth Science》2023年第1期322-336,共15页地球科学前沿（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(Grant Nos.U19B6003-03-01 and 42030804);the Fundamental Research Funds for the Central Universities(No.2652019101).

摘　　要：Recently, deeply-buried shale (depth > 3500 m) has become an attractive target for shale gas exploration and development in China. Gas-in-place (GIP) is critical to shale gas evaluation, but the GIP content of deep shale and its controlling factors have rarely been investigated. To clarify this issue, an integrated investigation of deep gas shale (3740–3820 m depth) of the Lower Paleozoic Wufeng–Longmaxi Formations (WF–LMX) in the Dingshan area, Sichuan Basin had been carried out. Our results show that the GIP content of the studied WF–LMX shale in the Dingshan area ranges from 0.85 to 12.7 m^(3)/t, with an average of 3.5 m^(3)/t. Various types of pores, including organic matter (OM) pore and inorganic pore, are widely developed in the deep shale, with total porosity of 2.2 to 7.3% (average = 4.5%). The OM pore and clay-hosted pore are the dominant pore types of siliceous shale and clay-rich shale, respectively. Authigenic quartz plays a critical role in the protection of organic pores in organic-rich shales from compaction. The TOC content controls the porosity of shale samples, which is the major factor controlling the GIP content of the deep shale. Clay minerals generally play a negative role in the GIP content. In the Sichuan Basin, the deep and ultra-deep WF–LMX shales display the relatively high porosity and GIP contents probably due to the widespread of organic pores and better preservation, revealing great potentials of deep and ultra-deep shale gas. From the perspective of rock mechanical properties, deep shale is the favorable exploration target in the Sichuan Basin at present. However, ultra-deep shale is also a potential exploration target although there remain great challenges.

关 键 词：Deep shale porosity organic pore gas potential authigenic quartz 

分 类 号：P618.13[天文地球—矿床学]