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软煤层钻进过程中孔壁失稳破坏形成钻穴是致使钻进困难的主要原因。建立常态钻孔、开放型钻穴和填充型钻穴排渣模型,对孔内钻屑运移进行气固耦合动力学分析。研究结果表明,开放型钻穴对钻屑运移的影响较小,仅带来一定的压力损耗;填充型钻穴在钻孔底部的钻屑质量分数成倍增长,钻屑颗粒运动轨迹曲折,排出需要更长时间;填充型钻穴区出现瞬间动压波峰,压差损耗是常态钻孔、开放型钻穴的数倍。基于钻穴区钻屑运移特征,提出降低钻杆排渣阻力、增大排渣空间的钻具设计方法,研制了刻槽螺旋钻杆、低螺旋钻杆、等离子熔涂螺旋钻杆等系列钻杆,通过工程应用,软煤层钻进深度和钻进效率得到了有效改善。
The main cause of drilling difficulties is the formation of drill holes due to the instability of the hole wall during the drilling process of soft coal seams. The normal drilling, open drill hole and filled drilling hole model were established to study the gas-solid coupling dynamics of drill cuttings in the hole. The results show that the open drill hole has little influence on the migration of drill cuttings and only brings some pressure loss; the drill cuttings mass fraction at the bottom of the drill hole multiplied by the filled drill hole, the twists and turns of drill cuttings particle trajectory, Discharge takes longer time; filling drill hole area appear instant dynamic pressure wave peak, pressure loss is normal drilling, open drill hole several times. Based on the characteristics of drill cuttings in drill hole area, a drilling tool design method was proposed to reduce the drag of drill pipe and increase the space for slagging. A series of drilling helical drill pipe, low helical drill pipe and plasma melting helical drill pipe were developed Drill pipe, through engineering applications, soft coal bed depth and drilling efficiency has been effectively improved.