Roles of coal heterogeneity on evolution of coal permeability under unconstrained boundary conditions

Chen, Zhongwei, Liu, Jishan, Elsworth, Derek, Pan, Zhejun and Wang, Shugang (2013) Roles of coal heterogeneity on evolution of coal permeability under unconstrained boundary conditions. Journal of Natural Gas Science and Engineering, 15 38-52. doi:10.1016/j.jngse.2013.09.002

Author Chen, Zhongwei
Liu, Jishan
Elsworth, Derek
Pan, Zhejun
Wang, Shugang
Title Roles of coal heterogeneity on evolution of coal permeability under unconstrained boundary conditions
Journal name Journal of Natural Gas Science and Engineering   Check publisher's open access policy
ISSN 1875-5100
Publication date 2013
Year available 2013
Sub-type Article (original research)
DOI 10.1016/j.jngse.2013.09.002
Volume 15
Start page 38
End page 52
Total pages 15
Place of publication Philadelphia, PA United States
Publisher Elsevier Inc
Collection year 2014
Language eng
Subject 2102 Curatorial and Related Studies
Abstract Coal permeability models based on constrained conditions such as constant volume theory can successfully match unconstrained experimental data and field observations. However, these models have a boundary mismatch because the boundary of permeability models is constrained while experiment boundary is free displacement or unconstrained. What the mechanism is to require such a boundary mismatch has not been well understood. In this study, a full coupled approach was developed to explicitly simulate the interactions of coal matrixes and fractures. In this model, a matrix-fracture model is numerically investigated after incorporating heterogeneous distributions of Young's modulus, Langmuir strain constant in the vicinity of the fracture. The impact of these local heterogeneities of coal mechanical and swelling properties on the permeability evolution is explored. The transient permeability evolution during gas swelling process is investigated and the difference between the final equilibrium permeability and transient permeability is compared. With the heterogeneity assumption, a net reduction of coal permeability is achieved from the initial no-swelling state to the final equilibrium state. This net reduction of coal permeability increases with the fracture (injection) pressure and is in good agreement with laboratorial data under the unconstrained swelling conditions. Coal local heterogeneity in vicinity of fracture can therefore be the mechanism of the above mismatch.
Keyword Coal permeability
Coal swelling
Coal-gas interaction
Gas sorption
Local heterogeneity
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mechanical & Mining Engineering Publications
Official 2014 Collection
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