Analysis on Production of Coal Bed Methane Considering the Change in Permeability of Coal Rock
Zhu Likai1, 2, Ji Youjun3, 4, *, Yang Tianhong1, Li Xiaoyu3
1 Center for Rock Instability and Induced Seismicity Research, Northeast University, Shenyang 110819, China
2 Shenyang Research Institute of China Coal Science and Industry Group, Shenyang 110016, China
3 State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, 610500, China
4 School of Geoscience and Technology, Southwest Petroleum University, Chengdu, 610500, China
Based on the mechanism of migration of the coal bed methane (CBM), and taking into account the deformation of the coal rock during the process of CBM production was also taken into account, a coupled mathematical model considering the interaction of solid and fluid for methane extraction was built. The coal gas extraction of JINcheng coal mine was taken as an example, some typical coal sample was chosen to test the permeability under different confining pressure. The curve for permeability of coal rock versus effective stress under different confining pressure was obtained, a numerical model considering the variation of permeability for methane extraction was set up. The influence of deformation of coal rock on the gas production was simulated and analyzed. The simulation results indicate that the productivity curve considering deformation of rock is closer to the actual production data, at the initial stage of production, the gas rate is less than the case without considering deformation of rock, but the time of stable yield will last longer, and this matches the actual methane extraction, therefore, we recommend that the deformation of coal seam should be considered during the prediction of methane production for JINcheng coal mine.
Keywords: Deformation, Methane, Numerical Simulation, Prediction for production of CBM.
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* Address correspondence to this author at the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, 610500, China; Tel: +86 18380172978; E-mail: email@example.com.