射孔对煤层扩孔段地应力分布影响的分析

Effect of Perforation on In-situ Stress of Enlarged Holes of Coal Seam

在煤层扩孔时由于扩径比过大,扩径钻井时钻具工作扭矩相应也会很大,扩孔钻井工艺实现困难。为此提出了在扩孔前期利用射孔工具在煤岩中先进行射孔的方法,改变目的层煤岩应力,降低煤岩剪切强度,最终达到减小钻头切削接触力,降低钻头工作扭矩,提高钻井效率的目的。建立了煤层扩孔段有限元模型,给出了无射孔时煤层扩孔段井眼的应力分布,同时就煤层扩孔段布孔方案对井眼地应力分布的影响进行了研究。通过不同射孔方案对地应力的影响来确定最终优化的布孔方案。

The reaming diameter ratio was too large to be reamed in coal seam,therefore the operation torque in drilling under reamer would be bigger and it was difficult to implement drilling technique for reamer,Thus it was proposed that perforating tools were used for drilling in the coal seam at initial stage of reaming to change the stress in the coal seam,reduce the contact force on bit and lower drilling torque in order to improve the drilling efficiency.In this paper,the finite element model of coal seam reaming segment is established,a non-perforated section of the borehole reaming seam stress distribution is given,and wellbore stress distribution of the coal-hole reaming section to the program is studied.The optimized program of hole distribution could be determined by various perforation programs.