Application of gas ground well extraction technology in aquifer formation in mining area

In Duanshi Coal Mine of Shanxi Province, it is found that there is a large amount of water flowing through the formation when the coal bed methane extraction technology is applied to the ground well in the mining area, the formation water inflows from the damaged wellbore into the casing to block the extraction passage, resulting in poor gas production. In order to solve this problem, the damage mode of wellbore was analyzed to determine the aquifer formation position and further optimize the drilling-cementing technology and wellbore structure, after the improvement, the extraction effect of surface well was improved significantly; the effective operation time increased from 30 d to 180 d, and the pure volume of gas extraction increased from 159 500 m³ to 1 722 500 m³, after the operation of ground well, the gas concentration of return air roadway and upper corner of the working face decreased by 29.60% and 46.27% respectively, and there was no increase in water inflow in the underground working face. The field test results show that the extraction technology of ground well in the mining area can be successfully applied in the aquifer occurrence area after optimization and improvement.