IEU钻杆刺穿断裂原因分析

Failure Analysis of IEU Drill Pipes

某油田C1井用的一批127.0 mm×9.19 mm IEU G105钻杆,当纯钻时间2367 h、进尺8769 m时,发生了多起钻杆刺穿和断裂事故。对钻杆的使用工况和受力状态、结构尺寸、化学成分、力学性能、断口宏观形貌和微观形貌、金相组织和腐蚀产物等进行了检测和分析;对钻杆材质腐蚀疲劳裂纹扩展速率进行了测定。结果表明,钻杆刺穿和断裂属于早期腐蚀疲劳失效;钻杆腐蚀疲劳失效既与钻杆本身的结构和材料质量有关,也与钻杆使用井的结构和环境状况有关。

Many 127. 0 mm× 9. 19 mm IEU G105 drill pipes failea after 2 367 h of pure drilling time with 8 726 m of penetration footage. The service and loading conditions configuration dimensions, chemical composition, mechanical properties, metallography, macro-fractography, micro-fractography, and corrosion products of the drill pipes were anolyzed. Crack extending velocity of the drill pipe material in corrosion medium was also tested. The results, indicated that the fracfure of the drill pipe resulted from premature corrosion fatigue failure. The failure courses might be as follows.. Corrosion pits occurred first at the internal surface in the stress concentrating area of the drill pipe, and then fatigue cracks initiated in pit bottoms, and fractured finally as cracks penetrated through the wall thickness of the drill pipe. The fracture was related to the configuration, material quality and load condition of the drill pipe.