Oil & Gas Geology ›› 2021, Vol. 42 ›› Issue (1): 107-123.doi: 10.11743/ogg20210110

• Petroleum Geology • Previous Articles     Next Articles

Characteristics and exploration potential of the Wufeng-Longmaxi shale gas reservoirs of Lower Paleozoic in Yichang area, western Hubei Province, China

Quansheng Cai1,2(), Xiaohong Chen2,*(), Guotao Zhang2, Baomin Zhang2, Jing Han3, Lin Chen2, Peijun Li2, Yangui Li4   

  1. 1. School of Geosciences, Yangtze University, Wuhan, Hubei 430100, China
    2. Wuhan Institute of Geology and Mineral Resources, China Geological Survey, Wuhan, Hubei 434025, China
    3. Research Institute of SINOPEC Petroleum Exploration Branch Company Ltd., Chengdu, Sichuan 610041, China
    4. Chinese Academy of Geological Sciences, Beijing 100037, China
  • Received:2019-05-22 Online:2021-02-28 Published:2021-02-07
  • Contact: Xiaohong Chen E-mail:cqsh0713@163.com;yccxiaohong@163.com

Abstract:

During the past few years, several shale gas discoveries were made in the Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation in Yichang of western Hubei Province, China.The shale gas potential of the formations was then explored by combining the previous studies with updated analyses of drilling data and outcrops, geophysical information and testing results.A summary of the development characteristics, reservoir distribution and resource potential of the formations shows that the targeted dark, organic-rich rocks at the lower part of the formations have high quartz content (more than 50% on average) and TOC(2.47% on average), and high maturity (Ro of more than 2% in general), low porosity (less than 5% in general), extra-low permeability (0.19×10-3 μm2 on average), and relatively high gas content (2.0 m3/t on average).Quality reservoirs are mostly distributed in the lower part (about 11 m thick) of the black rocks and can be corresponded to the WF2-WF3 Katian graptolite zone and LM2-LM3 Rhuddanian graptolite zone.The reservoirs are thinner than high-quality reservoirs in Jiaoshiba and Changning areas, Sichuan Province.However, judging by their preservation conditions and economy, we propose that the rocks in the slope of eastern Yichang with their shallower burial depth, relatively better preservation conditions as well as a geological reserve of over 1 200×108 m3, are worthy of further exploration.

Key words: exploration potential, shale gas, reservoir characteristics, Wufeng Formation, Longmaxi Formation, Yichang area

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