高压脉冲水射流顶底板钻孔提高煤层瓦斯抽采率的应用研究

在分析松软煤层中钻孔塌孔、硬分层中成孔机理的基础上，提出利用高压脉冲水射流在硬分层或顶底板中钻孔，切至软分层提高瓦斯抽采率的新钻孔工艺。并基于高压脉冲射流破煤岩动力特性，分析计算了射流在松软煤层中切缝所需的射流压力及流量；研制出钻孔、切缝系统装置及工艺。在四川某煤矿的松软煤层进行了现场试验，应用结果表明钻孔深度是本煤层钻孔深度的2.7倍，平均单孔瓦斯的抽放纯量为0.19~0.26 m³/min，是采用原工艺钻孔的5.2倍以上。

Application of Technique of Drilling Between Roof and Floor with High Pressure Pulse Water Jet

Owing to low coal strength and high gas pressure, the borehole drilling in the soft seam is hard to reach usable length. Then the gas in soft seam is difficult to drain. For that, it is necessary to analyze the mechanism of borehole collapse in soft seam and borehole completed in hard seam. On that basis, the thesis provides a new way of drilling borehole, which is drilling borehole in hard seam, floor or roof and then slotting the coal with high pulsed pressure water jet. The first important parameters are pressure and flow quantity, which are analyzed according as the parameter of the coal seam of a Sichuan mine. Then the gas drainage system of high pressure pulsed water jet has been developed and applied successfully in a typical mine with rich gas and low permeability in Sichuan. According to the results, the borehole length drilled by new technology is 2.7 times of the original. Besides, the drainage flux mount per borehole is 1.872m3/min, 7.2 times of the original, and the drainage concentration is 66.8%, 3.5 times of the original.