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Advances in Geo-Energy Research 2021, 5(1): 104-118 https://doi.org/10.46690/ager.2021.01.10
Original Article | Open Access | Issue | Published: 12 March 2021

A multi-field coupling model of gas flow in fractured coal seam

Show Author's Information Dayu Ye1,2,  Guannan Liu1,2,3( ),  Feng Gao1,2,3,  Rongguang Xu4,  Fengtian Yue2,3
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, P. R. China
Mechanics and Civil Engineering Institute, China University of Mining and Technology, Xuzhou 221116, P. R. China
Laboratory of Mine Cooling and Coal-heat Integrated Exploitation, China University of Mining and Technology, Xuzhou 221116, P. R. China
Department of Mechanical and Aerospace Engineering, The George Washington University, Washington 20052, USA
Keywords:
gas sorption, Fractal, coal permeability, coal microstructure, thermal conduction
Cite this article:
Ye D, Liu G, Gao F, et al. A multi-field coupling model of gas flow in fractured coal seam. Advances in Geo-Energy Research, 2021, 5(1): 104-118. https://doi.org/10.46690/ager.2021.01.10
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Abstract Full text About this article

The structure of fractures and pores has a dominant impact on the heat transfer-seepage-deformation process of a coal seam. Previous models have primarily used the cubic permeability model to characterize coal seam permeability properties. In this study, we developed a new multi-field coupling model, which includes fracture and pore structure, coal seam temperature, effective stress and gas seepage. Two major extraction scenarios were simulated: the unconstrained plane strain state and the uniaxial plane strain state. In addition, two microstructural parameters were applied to characterize coal permeability: the maximum fracture length and the fractal dimension for the fracture. The results show that the fractal seepage model provides a more realistic and reliable characterization of resource migration and extraction processes in unconventional reservoirs than the cubic-law permeability model. Compared with the cubic-law permeability model, the permeability calculated by the model proposed in this paper changes about 17.09%-91.56%. Furthermore, coal seam permeability is proportional to the maximum fracture length and the fractal dimension for the fracture. The permeability changes about 17.09% and 17.18% with the different fractal dimension, and about 87.17% and 91.56% with the different maximum fracture length. However, the fractal dimension and coal seam permeability are inversely proportional to seam temperature.


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About this article

A multi-field coupling model of gas flow in fractured coal seam

Show Author's information Dayu Ye1,2, Guannan Liu1,2,3( ), Feng Gao1,2,3, Rongguang Xu4, Fengtian Yue2,3
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, P. R. China
Mechanics and Civil Engineering Institute, China University of Mining and Technology, Xuzhou 221116, P. R. China
Laboratory of Mine Cooling and Coal-heat Integrated Exploitation, China University of Mining and Technology, Xuzhou 221116, P. R. China
Department of Mechanical and Aerospace Engineering, The George Washington University, Washington 20052, USA

Abstract

The structure of fractures and pores has a dominant impact on the heat transfer-seepage-deformation process of a coal seam. Previous models have primarily used the cubic permeability model to characterize coal seam permeability properties. In this study, we developed a new multi-field coupling model, which includes fracture and pore structure, coal seam temperature, effective stress and gas seepage. Two major extraction scenarios were simulated: the unconstrained plane strain state and the uniaxial plane strain state. In addition, two microstructural parameters were applied to characterize coal permeability: the maximum fracture length and the fractal dimension for the fracture. The results show that the fractal seepage model provides a more realistic and reliable characterization of resource migration and extraction processes in unconventional reservoirs than the cubic-law permeability model. Compared with the cubic-law permeability model, the permeability calculated by the model proposed in this paper changes about 17.09%-91.56%. Furthermore, coal seam permeability is proportional to the maximum fracture length and the fractal dimension for the fracture. The permeability changes about 17.09% and 17.18% with the different fractal dimension, and about 87.17% and 91.56% with the different maximum fracture length. However, the fractal dimension and coal seam permeability are inversely proportional to seam temperature.

Keywords: gas sorption, Fractal, coal permeability, coal microstructure, thermal conduction

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Publication history

Received: 25 February 2021
Revised: 08 March 2021
Accepted: 09 March 2021
Published: 12 March 2021
Issue date: March 2021

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© The Author(s) 2021

Acknowledgements

This work was supported by the Fundamental Research Funds for the Central Universities (No. 2020ZDPYMS02).

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This article is distributed under the terms and conditions of the Creative Commons Attribution (CC BY-NC-ND) license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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