煤矿井下硬岩定向钻进孔底水力加压技术

Hole-bottom hydraulic pressurization technology for directional drilling in hard rock in underground coal mines

为解决煤矿井下硬岩深孔滑动定向钻进过程中因钻柱托压效应引起的给进压力大、钻进效率低、钻孔深度受限等问题,提出了采用孔底水力加压方式提高钻头钻压的技术思路。通过借鉴石油钻井领域水力加压器结构并结合煤矿井下近水平孔钻进工况进行了孔底水力加压器结构设计,运用理论计算和数值模拟方法进行了水力参数设计。对样机进行了室内测试,测试结果表明,采用Φ12 mm、Φ13 mm、Φ14 mm活塞水眼在流量200～450 L/min范围内输出轴向压力2～10 kN。在淮南张集矿进行了现场试验,并总结出了一套孔底水力加压和水力辅助加压工艺,试验结果表明,滑动定向钻进方式下钻孔深度由464m顺利延伸至578m,深孔钻进时最大钻效由之前托压孔段的1 m/h以下提高至3 m/h以上,试验进尺内平均给进表压较托压孔段降低了23.8%、平均钻效提高了137%。

In order to solve the problem of large feeding pressure,low drilling efficiency and limited hole depth caused by the backing effect of drill string during directional drilling of deep hole in underground coal mines,a technical idea of using hydraulic tool to increase WOB was proposed.The structural design of the hydraulic pressurizer at the bottom of the hole was carried out by drawing on the structure of the hydraulic pressurizer in the field of oil drilling and combining the nearly horizontal drilling conditions in underground coal mines.The hydraulic parameters were designed by the theoretical calculation and the numerical simulation method.The indoor test results show that the axial force 2-10 kN is output in the range of flow 200-450 L/min with 12 mm,13 mm,and 14 mm of the piston hole.Field test was carried out in Zhangji coal mine and a set of hole-bottom hydraulic pressurization and auxiliary pressurization were summed up.The test results show that the drilling depth was smoothly extended from 464 m to 578 m under the sliding directional drilling method.The maximum drilling efficiency of the deep hole drilling was increased from below 1 m/h to more than 3 m/h.The feeding pressure was reduced by 23.8% and the average drilling efficiency was increased by 137%.