某S135钻杆接头刺漏原因分析

Cause Analysis on Leakage of a S135 Drill Pipe Joint

为探究某井钻杆接头刺漏失效原因,通过宏观观察、无损检测、化学成分分析、力学性能测试、金相检测、扫描电镜(SEM)等手段,对该失效钻杆接头进行了综合分析。结果表明,钻杆接头刺漏的主要原因是钻杆接头在井下作业时承受拉伸、压缩、弯曲等复杂载荷作用,钻柱发生剧烈振动造成松动现象或上扣扭矩不足,高压钻井液进入接头缝隙形成冲蚀孔,萌生裂纹,在拉伸、压缩、弯曲等复杂载荷和Cl-作用下发生裂纹扩展,裂纹穿透整个壁厚,最终导致钻杆接头刺漏失效。

In order to explore the cause of drill pipe joint leakage in a well,the failure drill pipe joint was comprehensively analyzed by means of macro observation,non-destructive testing,chemical composition analysis,mechanical property testing,metallographic testing and scanning electron microscope(SEM).The results show that the main cause of drill pipe joint leakage is that the drill pipe joint bears complex loads such as tension,compression and bending during downhole operation,the drill string vibrates violently resulting in loosening or insufficient make-up torque,the high pressure drilling fluid enters into the joint gap to form erosion holes,cracks initiate,the crack propagation occurs under complex loads such as tension,compression and bending and Cl-.The crack penetrates the whole wall thickness,and eventually leads to drill pipe joint leakage failure.