石油钻杆刺穿失效原因分析

某石油钻杆在油田使用过程中发生早期刺穿失效。运用理化检测技术对失效的钻杆进行宏观形貌、化学成分、显微组织、力学性能分析和硬度测定。结果表明,钻井过程中在腐蚀介质的作用下,在钻杆内壁起刺处首先形成腐蚀坑,在复杂交变应力载荷作用下,钻杆表面腐蚀坑底部形成微裂纹并迅速扩展,最终导致钻杆发生腐蚀疲劳失效。为预防此类失效的发生,要严格控制钢管轧制工序,选用合适轧制工具尺寸,提高钢管内外壁表面质量,避免钻杆在油田使用时再次发生腐蚀疲劳失效。

Cause analysis and prevention of oil drill pipe puncture failure

Early perforation failure of a drill pipe occurred in the process of using in the oil field. The macroscopic morphology, chemical composition, microstructure, mechanical properties and hardness of the failed drill pipe were analyzed by physical and chemical testing technology. The results show that under the action of corrosive medium in the process of drilling, a corrosion pit forms at the pricking point of inner wall of the drill pipe. Under the action of complex alternating stress load, microcracks form at the bottom of the corrosion pit on the surface of the drill pipe and propagates rapidly, resulting in the corrosion fatigue failure of the drill pipe. In order to prevent this kind of failure, it is necessary to strictly control the steel pipe rolling process, select the appropriate rolling tool size, improve the surface quality of the inner and outer walls of the steel pipe, and avoid the corrosion fatigue failure of the drill pipe used in the oil field.