Study on the law of drainage range and flow of surface well in mining area

The spacing of surface wells in the mining area of coal mines mostly depends on engineering experience and lacks scientific theoretical basis at present. In order to solve this problem, the numerical simulation software of COMSOL Multiphysics was used to establish a three-dimensional numerical model to calculate the scalar gas drainage and gas concentration distribution in goaf of surface well drainage in mining area. Based on the related physical property parameters of Yuecheng Coal Mine, the coal and rock permeability, porosity and gas quality source terms that in accordance with the actual conditions were calculated, and the numerical simulation was carried out on this basis. The simulation analysis results show that:in the numerical simulation, the influence radius of surface well gas extraction is 65 m, the variation of scalar gas drainage from surface well is characterized by "single peak and long tail".If the full coverage of gas drainage in mining area is to be realized, the spacing of surface wells should be more than 130 m in practical engineering application. The research results have guiding significance for optimizing the surface well layout in mining area.