Determination and Analysis of Influencing Factors of Coalbed Methane Weathering Zone in Zhunnan Coalfield

By comparing the low-rank coalbed methane exploration and development data in the two major mining areas of Zhunnan Coalfield, it is found that the methane weathering zone in Liuhuanggou Mining Area is 670 m, while in the Fukang Mining Area is 450 m. The differences of hydrogeological conditions have led to large differences in the methane weathering zones of the two major mining areas. Further research found that the main controlling factor of causing the differences is the presence or absence of the aquifer in the fire areas: because of the existence of the fire areas in Fukang Mining Area, the permeability of the burnt-rock series in the fire zones is strongly modified, becoming the most direct surface water seepage compensation channel. On the one hand, the formed aquifer isolates oxygen effectively and avoids oxidation of the coal seam; on the other hand, the underwater seepage hinders the escape of coal-bed methane effectively and decreases the loss of coalbed methane. As a result, the methane weathering zone is shallower than those areas without fire zones in Liuhuanggou Mining Area.