Understanding of Gas Storage and Migration Pathways in Shales: Example from Pore Characteristics of Gufeng Formation
K. Wu†*, Q. L. Feng‡
†Faculty of Economics and Management, China University of Geosciences, Wuhan 430074, China,
‡State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China
ABSTRACT: To evaluate the hydrocarbon generation capacity and gas storage capacity of shale series，it is important to study the pore structural features of reservoirs. The pore in shales is varied, different pore types are not the same meaning with gas storage and flow capacity. In this paper, we use field emission scanning electron microscopy to take the secondary electron mode to scan shales from the Gufeng Formation in Jianshi, six categories and ten types of pores have been detected. This shows: the main pore types in argillaceous limestone are intercrystal pores within mineral grains, microfracture and brittle mineral are well developed; In siliceous mudstone, we find many pyrite microspherulites and floccules, organopores size from the nanoscale to several microns; A large number of honeycomb holes and microfracture are widely distributed in carbonaceous shale, the main pore types are organic matter nanopores. The nanoscale pore characteristics are quite different with traditional reservoir. In these pore types, the highly possible types to form gas migration pathways are: (1) porous floccules; (2) pores of organic matter; (3) microchannel and microfracture; (4) pores between organic matter and minerals.
Keywords : Shale gas; Pore types; FESEM; Western Hubei; Gufeng Formation.
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