Controls of Gas Slippage and Effective Stress on the Gas Permeability of Coal

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  • Coal Reservoir Laboratory of National Engineering Research Center of CBM Development and Utilization, School of Energy Resources, China University of Geosciences, Beijing 100083, China

Received date: 2012-12-13

  Revised date: 2013-02-20

  Online published: 2013-10-10

Abstract

Dynamic coal reservoir permeability impacts the production of coalbed methane (CBM)and has been extensively studied.Gas (Helium)permeability change was measured under a 4.3MPa confining stress condition for 6 anthracite coal cores from the southern Qinshui Basin.Furthermore,controlling factors of the permeability change were investigated by comprehensively analyzing the effects of gas slippage and effective stress on the permeability.Results show that during gas pressure decline:①the permeability initially decreases but subsequently increases,during which the rebound begins at an inlet gas pressure of about 1.9MPa(corresponding to a mean gas pressure of 1.0MPa);②gas slippage phenomenon appears as the mean gas pressure falls bellow 1.0MPa;③the permeability is approximately negatively related to effective stress;④the permeability decreases due to the negative effect from effective stress as the inlet gas pressure is greater than 1.9MPa;while it increases when the pressure falls below 1.9MPa because the positive effect from gas slippage is stronger than the negative effect from effective stress.

Cite this article

LI Jun-qian,LIU Da-meng,YAO Yan-bin,CAI Yi-dong,WANG Lei . Controls of Gas Slippage and Effective Stress on the Gas Permeability of Coal[J]. Natural Gas Geoscience, 2013 , 24(5) : 1074 -1078 . DOI: 10.11764/j.issn.1672-1926.2013.05.1074

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