Numerical simulation of gas migration into mining-induced fracture network in the goaf  

作　　者：Cao Jie Li Wenpu 

机构地区：[1]State Key Laboratory of Gas Disaster Detection, Prevention and Emergency Control. Chongqing 400037. China [2]Chongqing Research Institute Co. Ltd. of China Coal Technology and Engineering Group, Chongqing 400037, China [3]State Key Laboratory of Coal Mine Disaster Dynamics and Control. Chongqing University. Chongqing 400044, China

出　　处：《International Journal of Mining Science and Technology》2017年第4期681-685,共5页矿业科学技术学报（英文版）

基　　金：financially supported by the National Key Research and Development Program (No. 2016YFC0801402);the National Natural Science Foundation of China (No. 51374236);Chongqing Research Program of Basic Research and Frontier Technology of China (No. cstc2015jcyj BX0076)

摘　　要：Gas extraction practice has been proven for the clear majority of coal mines in China to be unfavorable using drill holes in the coal seam. Rather, mining-induced fractures in the goaf should be utilized for gas extraction. To study gas migration in mining-induced fractures, one mining face of 10 th Mine in Pingdingshan Coalmine Group in Henan, China, has been selected as the case study for this work. By establishing the mathematical model of gas migration under the influence of coal seam mining, discrete element software UDEC and Multiphysics software COMSOL are employed to model gas migration in mining-induced fractures above the goaf. The results show that as the working face advances, the goaf overburden gradually forms a mining-induced fracture network in the shape of a trapezoid, the size of which increases with the distance of coal face advance. Compared with gas migration in the overburden matrix, the gas flow in the fracture network due to mining is far greater. The largest mining-induced fracture is located at the upper end of the trapezoidal zone, which results in the largest gas flux in the network. When drilling for gas extraction in a mining-induced fracture field, the gas concentration is reduced in the whole region during the process of gas drainage, and the rate of gas concentration drops faster in the fractured zone. It is shown that with gas drainage, the gas flow velocity in the mininginduced fracture network is faster.Gas extraction practice has been proven for the clear majority of coal mines in China to be unfavorable using drill holes in the coal seam. Rather, mining-induced fractures in the goaf should be utilized for gas extraction. To study gas migration in mining-induced fractures, one mining face of 10 th Mine in Pingdingshan Coalmine Group in Henan, China, has been selected as the case study for this work. By establishing the mathematical model of gas migration under the influence of coal seam mining, discrete element software UDEC and Multiphysics software COMSOL are employed to model gas migration in mining-induced fractures above the goaf. The results show that as the working face advances, the goaf overburden gradually forms a mining-induced fracture network in the shape of a trapezoid, the size of which increases with the distance of coal face advance. Compared with gas migration in the overburden matrix, the gas flow in the fracture network due to mining is far greater. The largest mining-induced fracture is located at the upper end of the trapezoidal zone, which results in the largest gas flux in the network. When drilling for gas extraction in a mining-induced fracture field, the gas concentration is reduced in the whole region during the process of gas drainage, and the rate of gas concentration drops faster in the fractured zone. It is shown that with gas drainage, the gas flow velocity in the mininginduced fracture network is faster.

关 键 词：Gas migration FRACTURES Mining-induced Numerical simulation 

分 类 号：TD712[矿业工程—矿井通风与安全]