采动区瓦斯地面井抽采技术在含水地层矿区的应用

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

山西端氏煤矿在应用采动区地面井抽采煤层气技术时发现钻越地层涌水量较大,地面井受采动影响后地层水从井壁破损处涌入套管内堵塞抽采通道,导致产气效果欠佳。针对这一问题,通过分析井身破坏模式,确定含水地层位置,进一步优化钻固井工艺及井身结构,改进后地面井抽采效果提升显著:有效运行时间从30 d增加到180 d,抽采瓦斯纯量由15.95万m3增加到172.25万m3,地面井运行后工作面回风巷瓦斯浓度降幅为29.60%,工作面上隅角瓦斯浓度降幅为46.27%,井下工作面涌水量没有增加。现场试验结果表明,采动区地面井抽采技术经过优化改进后可以在含水层赋存矿区成功应用。

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 159500 m3 to 1722500 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.