Reservoir Evaluation and Development ›› 2019, Vol. 9 ›› Issue (5): 45-53.

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Pore connectivity of marine high-maturity shale gas reservoirs: A case study in Longmaxi formation, Pengshui area

XIAO Dianshi1,LU Shuangfang1,FANG Dazhi2,KONG Xingxing1,CHEN Fangwen1,LI Jijun1   

  1. 1. Key Laboratory of Deep Oil and Gas, China University of Petroleum(East China), Qingdao, Shandong 266580, China
    2. Nanchuan Shale Gas Project Department, Sinopec East China Oil and Gas Company, Chongqing 408400, China
  • Received:2019-06-25 Online:2019-10-26 Published:2019-10-26

Abstract:

Micro-pore connectivity affects the seepage and production of shale gas, but there are less research on shale connectivity currently. Taking the Wufeng-Longmaxi formation shale gas reservoir in Pengshui area as an example, the connected pore assemblages of shale gas reservoirs were classified, and then the pore-throat connections of different types of shales were discussed based on a variety of experimental methods. Four types of connected pore assemblages were classified in shale, that is, organic pore interconnection, organic pore-micro-fracture interconnection, organic pore-clay pore interconnection, and clay pore-intergranular pore interconnection. Organic-rich shale, mainly composed of interconnected organic pore assemblages, conforms to the short-conduit pore-throat assemblage model with the minimum pore-throat ratio. While medium-low organic shale, mainly composed of interconnected organic pore-clay pore assemblages, is a composite model of short-conduit and tree-shaped pore with the relatively large pore-throat ratio. When the ratio of TOC/clay mineral content decreases, the tree-shaped pore-throat ratio increases and the pore-throat ratio decreases. The combination of small pore throat ratio and high content organic pore interconnection is conducive to reducing water lock damage caused by fracturing fluid retention.

Key words: shale reservoirs, pore assemblages, pore-throat connectivity, pore-throat structure, Pengshui area

CLC Number: 

  • TE37