文献类型：期刊文献

英文题名：Evolution of Coal Permeability during Gas InjectionFrom Initial to Ultimate Equilibrium

作者：Liu, Xingxing[1,2];Sheng, Jinchang[1];Liu, Jishan[3];Hu, Yunjin[4]

机构：[1]Hohai Univ, Coll Water Conservancy & Hydropower Engn, Nanjing 210098, Jiangsu, Peoples R China;[2]China Univ Min & Technol, Beijing Key Lab Precise Min Intergrown Energy & R, Beijing 100083, Peoples R China;[3]Univ Western Australia, Sch Engn, Dept Chem Engn, 35 Stirling Highway, Perth, WA 6009, Australia;[4]Shaoxing Univ, Sch Civil Engn, Shaoxing 312000, Peoples R China

年份：2018

卷号：11

期号：10

外文期刊名：ENERGIES

收录：SCI-EXPANDED(收录号：WOS:000449293500308)、、EI(收录号：20184506041838)、Scopus(收录号：2-s2.0-85055966758)、WOS

基金：This research is funded by the National Natural Science Foundation of China (Nos. 51474204 and 51579078), the Fundamental Research Funds for the Central Universities (No. 2015B32114) and Collaborative Innovation Center for Prevention and Control of Mountain Geological Hazards of Zhejiang Province (No. PCMGH-2017-Z-02).

语种：英文

外文关键词：equilibrium permeability; non-equilibrium permeability; matrix-fracture interaction; effective stress; coal deformation

外文摘要：The evolution of coal permeability is vitally important for the effective extraction of coal seam gas. A broad variety of permeability models have been developed under the assumption of local equilibrium, i.e., that the fracture pressure is in equilibrium with the matrix pressure. These models have so far failed to explain observations of coal permeability evolution that are available. This study explores the evolution of coal permeability as a non-equilibrium process. A displacement-based model is developed to define the evolution of permeability as a function of fracture aperture. Permeability evolution is tracked for the full spectrum of response from an initial apparent-equilibrium to an ultimate and final equilibrium. This approach is applied to explain why coal permeability changes even under a constant global effective stress, as reported in the literature. Model results clearly demonstrate that coal permeability changes even if conditions of constant effective stress are maintained for the fracture system during the non-equilibrium period, and that the duration of the transient period, from initial apparent-equilibrium to final equilibrium is primarily determined by both the fracture pressure and gas transport in the coal matrix. Based on these findings, it is concluded that the current assumption of local equilibrium in measurements of coal permeability may not be valid.