Oil & Gas Geology ›› 2022, Vol. 43 ›› Issue (2): 365-377.doi: 10.11743/ogg20220210

• Petroleum Geology • Previous Articles     Next Articles

Sedimentary characteristics and model of platform-trough shale in the Lower Carboniferous, Guizhong Depression, Dianqiangui Basin

Jinyu Tao1,2,3,4(), Zongquan Hu5, Baojian Shen1,2,3,4, Anyang Pan1,2,3,4, Chuxiong Li1,2,3,4, Ruihu Wang6, Meiling Zhang6   

  1. 1.Wuxi Research Institute of Petroleum Geology,Petroleum Exploration and Production Research Institute,SINOPEC,Wuxi,Jiangsu 214126,China
    2.State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Wuxi,Jiangsu 214126,China
    3.State Energy Center for Shale Oil Research and Development,Wuxi,Jiangsu 214126,China
    4.Key Laboratory of Petroleum Accumulation Mechanisms,SINOPEC,Wuxi,Jiangsu 214126,China
    5.Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China
    6.The Institute of Geological Survey of Guangxi Zhuang Autonomous Region,Nanning,Guangxi 530022,China
  • Received:2020-07-31 Revised:2022-01-20 Online:2022-04-01 Published:2022-03-11

Abstract:

The sedimentary characteristics of shale in the Lower Carboniferous Luzhai Formation, Guizhong Depression are discussed based on observation and description of cores from typical wells, outcrop observation and laboratory tests. A sedimentary model of the platform-trough facies is thereby established, and the potential zones favorable for shale gas exploration are proposed. In comparison, the differences between shales of shelf facies (as represented by the Wufeng-Longmaxi shale, Sichuan Basin) and platform-trough facies (as represented by shale in the study area) are clarified. In addition to facies markers of lamellation, deformation, and grain sequence typical of the bedding structure, large amount of pyrites are widely enriched in the trough. A calcareous and a siliceous turbidites, paleontological fragments like brachiopods together with some plant fragments, could be identified in the slope between platform and trough. According to the lithologic combination, facies markers and other hydrodynamic conditions, platform-trough facies could be subdivided into 4 subfacies and 13 types of lithofacies. Among others, the siliceous lithofacies and siliceous shale lithofacies in the platform-trough facies, together with the argillaceous siliceous lithofacies and carbonaceous mudstone lithofacies in trough slope subfacies, could be of the potential facies belts for shale gas exploration. The siliceous rocks with some lime and shale contents can be of potential targets for shale gas exploration.

Key words: platform-trough facies, depositional model, shale, Lower Carboniferous, Guizhong Depression, Dianqiangui Basin

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