Predicting permeability change of fractured coals during methane depletion

Xiang Zhou, Shimin Liu, Yida Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Assessing the evolution of apparent permeability of coal matrix during gas injection/extraction is crucial in coalbed methane (CBM) production. It is commonly found that permeability increases upon the primary depletion of CBM reservoirs. Such increase is mainly attributed to the desorption of methane molecules from the coal matrix which will then exhibit notable volumetric shrinkage and changes of the pore structures. Various permeability models exist for such system but often equipped with oversimplified the geomechanical representation of coals. This study attempts to improve this aspect by adopting the concept of adsorption stress to formulate a mechanistic theory for adsorption-deformation coupling in coals. The constitutive theory is implemented in a finite element (FE) scheme and then coupled with explicit representation of fractures by FE mesh. Coal methane depletion tests are simulated by the model and the results are compared against existing experimental data. Through parametric studies, the permeability curve is found to be controlled by a few factors. The proposed model has such flexibility to capture various types of permeability evolution trends that a cluster of measured permeability data from San Juan basin can be well covered.

Original languageEnglish (US)
Title of host publication55th U.S. Rock Mechanics / Geomechanics Symposium 2021
PublisherAmerican Rock Mechanics Association (ARMA)
ISBN (Electronic)9781713839125
StatePublished - 2021
Event55th U.S. Rock Mechanics / Geomechanics Symposium 2021 - Houston, Virtual, United States
Duration: Jun 18 2021Jun 25 2021

Publication series

Name55th U.S. Rock Mechanics / Geomechanics Symposium 2021


Conference55th U.S. Rock Mechanics / Geomechanics Symposium 2021
Country/TerritoryUnited States
CityHouston, Virtual

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics


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