某油田钻井公司使用的规格为101.6 mm×8.38 mm的G105钻杆先后发生两起管体刺穿失效事故，通过化学成分分析、力学性能测试、金相检验、X射线衍射等方法并结合钻杆的受力状态对钻杆刺穿原因进行了分析。结果表明: 钻杆刺穿失效形式为腐蚀疲劳，在钻井液中腐蚀介质作用下，钻杆首先发生氧腐蚀和Cl-加速腐蚀，使钻杆外表面产生许多腐蚀坑，并于腐蚀坑底部形成应力集中; 随后在钻井过程的交变应力作用下，应力集中严重的腐蚀坑底部开始萌生裂纹，裂纹不断疲劳扩展直至穿透管壁; 最终在钻杆内钻井液的冲刷作用下发生刺穿失效。

An investigation was made into the failure of a 101.6 mm×8.38 mm G105 drill pipe by chemical compositions analysis, mechanical properties test, metallographic examination and X-ray diffraction, and the stress of the drill pipe during drilling process was also discussed. The results show that the piercement of the drill pipe was corrosion fatigue. On the action of the corrosion mediator, oxygen corrosion firstly occurred on the drill pipe, and then Cl- accelerated the corrosion. Etch pits were generated on exterior surface of the drill pipe which result in stress concentration in bottom of the etch pits. The fatigue crack generated in bottom of the etch pits where the stress concentration were heaviest under alternate load, expanded and finally formed penetrated crack and came into being piercement under the scouring of high pressure drilling fluid.