Long-Term Evolution of Coal Permeability Under Effective Stresses Gap Between Matrix and Fracture During CO2 Injection

doi:10.1007/s11242-019-01350-7

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	Long-Term Evolution of Coal Permeability Under Effective Stresses Gap Between Matrix and Fracture During CO2 Injection
	Wei, Mingyao ; Liu, Jishan ; Shi, Rui ; Elsworth, Derek ; Liu, Zhanghao
刊名	TRANSPORT IN POROUS MEDIA
	2019
卷号	130 期号:3 页码:969-983
关键词	Coal permeability Gas adsorption Matrix swelling Equilibrium state Effective stress gap
ISSN号	0169-3913
DOI	10.1007/s11242-019-01350-7
英文摘要	Understanding the long-term evolution of coal permeability under the influence of gas adsorption-induced multiple processes is crucial for the efficient sequestration of CO2, coalbed methane extraction and enhanced coal bed methane recovery. In previous studies, coal permeability is normally measured as a function of gas pressure under the conditions of constant effective stresses, uniaxial strains and constant confining pressures. In all these experiments, an equilibrium state between coal matrix and fracture is normally assumed. This assumption has essentially excluded the effect of matrix-fracture interactions on the evolution of coal permeability. In this study, we hypothesize that the current equilibrium assumption is responsible for the discrepancy between theoretical expectations and experimental measurements. Under this hypothesis, the evolution of coal permeability is determined by the effective stress gap between coal matrix and fracture. This hypothesis is tested through an experiment of CO2 injection into a coal core under the constant effective stress. In this experiment, the effective stress in the fracture system is unchanged while the effective stress in the matrix evolves as a function of time. In the experiment, the coal permeability was measured continuously throughout the whole period of the experiment (similar to 80 days). The experimental results show that the core expands rapidly at the beginning due to the gas injection-induced poroelastic effect. After the injection, the core length remains almost unchanged. But, the measured permeability declines from 60 to 0.48 mu D for the first month. It rebounds slowly for the subsequent 2 months. These results indicate that the effective stress gap has a significant impact on the evolution of coal permeability. The switch of permeability from the initial reduction (the first 30 days) to rebound (the subsequent 50 days) suggests a transition of matrix deformation from nearby the fracture wall to further away area. These findings demonstrate that the evolution of coal permeability is primarily controlled by the spatial transformation of effective stresses between matrix and fracture.
WOS研究方向	Engineering
语种	英语
WOS记录号	WOS:000492323600001
内容类型	期刊论文
源URL	[http://119.78.100.198/handle/2S6PX9GI/14849]
专题	岩土力学所知识全产出_期刊论文
作者单位	1.China Univ Min & Technol, Natl & Local Joint Engn Lab Internet Applicat Tec, IoT Percept Mine Res Ctr, Xuzhou 221116, Jiangsu, Peoples R China; 2.Univ Western Australia, Sch Engn, 35 Stirling Highway, Perth, WA 6009, Australia; 3.China Univ Geosci, Key Lab Tecton & Petr Resources, Wuhan 430074, Peoples R China
推荐引用方式 GB/T 7714	Wei, Mingyao,Liu, Jishan,Shi, Rui,et al. Long-Term Evolution of Coal Permeability Under Effective Stresses Gap Between Matrix and Fracture During CO2 Injection[J]. TRANSPORT IN POROUS MEDIA,2019,130(3):969-983.
APA	Wei, Mingyao,Liu, Jishan,Shi, Rui,Elsworth, Derek,&Liu, Zhanghao.(2019).Long-Term Evolution of Coal Permeability Under Effective Stresses Gap Between Matrix and Fracture During CO2 Injection.TRANSPORT IN POROUS MEDIA,130(3),969-983.
MLA	Wei, Mingyao,et al."Long-Term Evolution of Coal Permeability Under Effective Stresses Gap Between Matrix and Fracture During CO2 Injection".TRANSPORT IN POROUS MEDIA 130.3(2019):969-983.