J55 LC套管断裂失效原因分析

针对油田生产过程中油套管断裂失效的问题，通过对失效管体尺寸测量、断口宏观和微观形貌分析以及管材理化性能检测等方法，对某公司J55 LC套管发生断裂失效的原因进行了分析。结果显示，断裂套管的化学成分、拉伸性能、金相组织、套管螺纹参数均符合相关标准要求，套管螺纹断裂失效位置正好处于螺纹啮合后全长上的齿面接触应力最大的部位，接触应力不当是引起套管断裂失效的主要原因。分析结果表明，套管断裂的主要原因为现场上扣作业控制不当，造成螺纹粘着磨损，使套管表面产生大量微裂纹，进而在螺纹接触应力最大处发生脆性断裂

Fracture Failure Analysis of J55 LC Casing

Aiming at the fracture failure of oil casing in oilfield production process, the causes of fracture failure of J55 LC casing in a company were analyzed by measuring the size of the failed tube, analyzing the macro and micro fracture morphology, and testing the physical and chemical properties of the pipe. The results show that the chemical composition, tensile properties, metallographic structure and thread parameters of the fractured casing meet the requirements of relevant standards. The fracture failure position of the casing thread is just at the position with the largest contact stress on the tooth surface of the full length after the thread engagement. Improper contact stress is the main reason for the casing fracture failure. The results show that the main cause of casing fracture is improper control of on-site make-up operation, resulting in adhesion wear of thread and a large number of micro cracks on the surface of casing, and then brittle fracture occurs at screw thread with the maximum contact stress.