Dual media model of shale layer with anisotropy involved and its simulation on gas migration

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  • 1.State Key Lab for Geomechanics & Deep Underground Engineering,CUMT,Xuzhou 221116,China;
    2.School of Mechanics & Civil Engineering,CUMT,Xuzhou 221116,China

Received date: 2015-06-18

  Revised date: 2016-04-20

  Online published: 2019-09-11

Abstract

It is necessary to accurately foresee the permeability of shale layers in fracturing optimization and gas-exploiting arrangement.Since integrating and reflecting all the influences of geological conditions,in-situ stress levels,adsorption-desorption effects on modeling is a progressive procedure,most of the permeability-foreseeing methods published nowadays could be improved naturally.In this paper,based on dual media theory,we firstly introduced a normal crack elastic modulus and considered infiltration anisotropy,and hence developed new porosity and permeability functions respectively for the matrix or fractures.After that,we employed them to build hydro-mechanical coupling equations with gas desorption and pore-fracture mass exchange.Finally,all the equations were transformed and utilized to simulate shale gas migration in the reservoir.The results show that reservoir pressure is not homogeneously distributed along three principal directions of permeability;within a well-service cycle,the developing degree of shale gas is not high in the horizontal direction around the well;Anisotropy upgrading obviously decreases gas production rate,and surprisingly a 3∶1 vertical-horizontal permeability difference would lead to a half decrease of gas production rate.

Cite this article

Liu Wei-qun, Wang Dong-ni, Su Qiang . Dual media model of shale layer with anisotropy involved and its simulation on gas migration[J]. Natural Gas Geoscience, 2016 , 27(8) : 1374 -1379 . DOI: 10.11764/j.issn.1672-1926.2016.08.1374

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