Study on gas drainage scope in surface well group under the influence of coal mining area

With the increasing intensity of coal mining in China, the amount of gas emission from the mining space has increased significantly. Even in low gas mines, there are gas explosion problems. How to carry out large-scale, regionalized continuous drainage and form a low-cost and long-term effective control of gas emission from the extraction space is still an important problem currently facing.It is an effective technology for regional continuous extraction to control the gas concentration in the mining space. Therefore, based on the analysis of seepage characteristics of overlying rock fracture field in mining area, the gas pressure attenuation gradient change function within the mining area around the surface well under the condition of the surface well in the mining area is established, and the judgment principle of effective extraction range of surface well is proposed based on the inflection point of gas pressure gradient attenuation curve in mining fracture field. Then, the evaluation method of gas drainage effect of surface wells in mining area is established, and the calculation model of gas drainage rate index is proposed. Finally, with Yuecheng mine of Jincheng Coal Group as the background, the method of combing COMSOL Multiphysics numerical simulation analysis and field small well group drainage test is used to optimize the parameters and application effects of the gas pressure attenuation gradient change function within the mining area around the surface well under the condition of the surface well in the mining area. Comparative analysis and verification have proved that gas drainage from surface wellgroups in the mining area has high practical value.