高瓦斯孤岛工作面预抽钻孔封孔工艺优化研究

针对王坡煤矿高瓦斯孤岛工作面预抽钻孔封孔质量差、抽采效果不理想的问题,基于围岩裂隙演化钻孔封堵原理,采用数值模拟和现场指标测试相结合的方法对巷道围岩应力场分布进行分析,进而确定了3210孤岛工作面抽采钻孔的合理封孔段深度为距煤壁15 m,并考虑距煤壁3 m范围内煤体破碎严重的问题,将原“两堵一注”封孔工艺优化为“三堵一注”封孔工艺。针对两种封孔工艺开展了现场抽采钻孔封孔试验,在60 d的抽采监测期内,优化工艺试验钻孔的平均甲烷体积分数为47.19%,较原有封孔工艺的平均甲烷体积分数高15.90%。现场试验结果表明,数值模拟与钻屑指标测定法综合确定合理封孔深度是科学有效的,抽采钻孔的封孔质量得到明显改善,抽采效果显著提高。

Study on Optimization of Sealing Technology of Gas Isolated Island Working Face with Pre-drainage Borehole

Aiming at poor sealing quality and unsatisfactory drainage effect of pre-drainage boreholes in high gas isolated island working face of Wangpo coal mine,the combination of laboratory numerical simulation and field index test was used to analyze the stress field distribution of surrounding rock of roadway.Furthermore,it was determined that the reasonable sealing depth of the 3210 island working face drainage hole was 15 m away from the coal wall.Considering the serious problem of coal body breakage within 3 m from the coal wall,the original"two plugging and one grouting"sealing process was optimized as the"three plugging and one grouting"sealing process.The field test was carried out for the two sealing processes.During the 60-day extraction monitoring period,the average gas volume fraction of the optimized process test boreholes was 47.19%,which was 15.90%higher than the average gas volume fraction compared with the original sealing process test boreholes.The field test results show that the comprehensive determination of the reasonable sealing depth with numerical simulation and the cuttings index measurement method is scientific and effective,the sealing quality of the extraction drilling hole is obviously improved,and the drainage effect is significantly improved.