Numerical Simulation On In-Situ Rock Stress Of Exploitation Process Through Injection Of Heat Into Low Permeability Coal Seam

There are rich coal-bed methane resources in China. But the production volume is so small that can not establish large-scale industrialized mining in most coal seams which are low permeability. Based on the character of low permeability coal seam and the regularity between desorption and seepage, in-situ rock stress is one of the important influence factors for coal-bed methane movement is found. And the numerical simulation analyses respectively to single well, double wells and nine wells collocation received the change laws and influence circle of in-situ rock stress field nearby the well before and after injection of heat. The results show: In-situ rock stress reduction is beneficial to coal-bed methane pulled out from the adsorption state after injecting heat into shaft. The coal-bed methane flows into the production shaft faster under greater pressure difference on the region outside of the thermal radius. It generates interference between wells when arranges multiple wells. It allows the rapid decline in reservoir stress and a large number of coal-bed methane is released. Especially for nine wells exploitation, the interference between wells is more obvious and differential pressure area is wider. Numerical simulation results provide guidance for exploitation through injection of heat into low permeability coal seam in our country.