某油井先后出现多起G105钢级钻杆刺漏事故，采用宏观观察、化学成分分析、金相检验、力学性能试验、微观分析、涂层质量评价、能谱分析等方法对钻杆的刺漏原因进行了分析，并对钻杆加厚过渡带的应力分布进行了有限元模拟分析。结果表明：钻杆的内涂层在井内腐蚀介质的长期影响下起泡脱落，钻杆内壁基体被腐蚀，在造斜井段交变载荷作用下于钻杆应力集中的加厚过渡带的腐蚀坑处产生疲劳裂纹，裂纹扩展最终导致钻杆刺漏。

Several drill pipe washout accidents of G105 steel grade occurred successively in an oil well. The causes of washout of the drill pipes were analyzed by means of macroscopic observation, chemical composition analysis, metallographic examination, mechanical property test, micro analysis, coating quality evaluation, energy spectrum analysis and so on. And the stress distribution in the intermediate belt of the drill pipe was simulated by finite element method. The results show that the inner coating of the drill pipes foamed and fell off under the long-term influence of the corrosion medium in the well, and the inner wall matrix of the drill pipes were corroded. Fatigue cracks produced in the corrosion pits of the intermediate belt of the drill pipes under alternating load in inclined section, and the crack propagation eventually led to washout of the drill pipes.