穿层钻孔挠性钻杆研制及应用

Development and application of flexible drill string in cross-measure borehole

针对高瓦斯工作面顶底板穿层钻孔有效抽采的煤孔段长度短，抽采率低的问题，研制了穿层钻孔挠性钻杆及其配套设备。通过三维建模计算分析，对挠性钻杆的结构进行优化设计；再通过室内模拟实验，测试挠性钻杆的抗扭强度、挠度及密封性能，试验结果表明，钻杆静态抗扭强度达到了4000N·m，挠曲率大于5°/m，且密封可靠，能够满足耐压8MPa的要求。现场工程实践表明：钻孔倾角20°～40°时，利用挠性钻杆施工钻孔的煤孔段长度达到设计长度2倍以上；倾角大于40°时，钻孔煤孔段长度达到设计长度1.5倍以上，钻孔煤孔段长度增大，瓦斯抽采率得到极大提高。

By the ways of 3D modeling and finite element analysis, the structure of flexible drill string was designed. The simulation results showed that the maximum deformation angle of the flexible drill string was 4.46° . By simulation experiments in laboratory, the torsional strength, deflection and leakproofness of the flexible drill string were tested. Experimental results showed that the torsional strength of the flex-ible drill string reached 4000Nm, deflection rate greater than 5＆#176;/m, and it could bear 8MPa pressure. The field application was in Panyi coal mine of Huainan mining （group） co., LTD. The maximum deflection intensity achieved 2°/m and the average deflection intensity was over 1.7°/m. The length in coal seam was more than twice the designed length in 20°40°; boreholes and 1.5 times the designed length in over 40＆#176; boreholes. The exceptive goal was achieved.