在对某油气井的钻探过程中,钻杆接头发生断裂。采用宏观观察、化学成分分析、扫描电镜分析、力学性能测试、金相检验等方法对该钻杆接头的断裂原因进行分析。结果表明:该钻杆接头的断裂性质为疲劳断裂,钻杆钻进过程中频繁发生跳钻、憋钻现象,使其瞬时载荷较大,在钻杆大端螺纹根部萌生了疲劳裂纹,在复杂的交变载荷作用下,裂纹快速扩展,最终导致钻杆接头发生断裂。

During the drilling process of a certain well, the drill pipe joint broke. The fracture reasons of the drill pipe joint were analyzed by macroscopic observation, chemical composition analysis, scanning electron microscope analysis, mechanical property test and metallographic examination. The results show that the fracture property of the drill pipe joint was fatigue fracture. During the drilling process, frequent jumping and holding of the drill pipe resulted in a large instantaneous load, and fatigue cracks initiated at the root of the large end thread of the drill pipe. Under complex alternating loads, the cracks rapidly expanded, ultimately led to the fracture of the drill pipe joint.