本煤层钻孔高压长距离封孔技术的研究与应用

Research and Application of High-Pressure Long-Distance Sealing Technology for Coal Seam Borehole

针对桑北矿本煤层瓦斯抽采钻孔封孔漏气的问题,分析了现行封孔工艺的漏气原因,研制了高压长距离自适应囊袋封孔器,并对封孔器结构及配套材料选型进行了优化分析。研究结果表明:封孔注浆压力偏低、穿层钻孔与本煤层钻孔“交叉漏气”是造成封孔漏气的根本原因;高压注浆封孔的合理注浆压力范围是1.5~2.0MPa,可有效封堵钻孔周围漏气通道和煤层裂隙;封孔深度设计为27m,可有效避开钻孔交叉漏气带;抽采管选择PE非常高密度材料能够满足高压长距离封孔的要求,设计抽采管直径为40mm、壁厚为4.5mm;通过工程应用,解决了封孔漏气问题,瓦斯平均抽采浓度提高了53.6%,长效性显著。

Aiming at the problem of gas leakage in the borehole sealing of gas extraction in the coal seam of Sangbei Coal Mine,the reasons of gas leakage in the current sealing process were analyzed,and a high-pressure long-distance adaptive bag sealing device was developed.The structure of the sealing device and the selection of supporting materials were optimized and analyzed.The results are concluded as follows.Firstly,the low pressure of sealing grouting and the cross leakage between the borehole and the coal seam are the fundamental reasons of sealing leakage.Secondly,the reasonable grouting pressure range of highpressure grouting sealing is 1.5-2.0MPa,which can effectively seal the gas leakage channels and coal seam cracks around the borehole.The sealing depth is designed to be 27m,which can effectively avoid the cross leakage zone of the borehole.Thirdly,the selection of PE very high-density material for the extraction pipe can meet the requirements of high-pressure long-distance sealing.Finally,through engineering application,the problem of sealing leakage is solved,and the average gas extraction concentration is increased by 53.6%,with significant long-term effectiveness.