某油管柱穿孔断裂的原因

Reasons for Perforation and Fracture of a Tubing String

通过对断裂油管进行断裂特征分析、材料性能分析和载荷分析,结合服役环境和运行情况,研究了该油管断裂的原因。结果表明,该油管中硫含量超标,其他元素含量、显微组织、力学性能等都符合标准要求。从断裂特征分析可知,断口表现为韧性断裂特征,无明显腐蚀。通过载荷计算可知,当断裂油管附近套管出现漏点时,环空和地层形成压差,油管在压差作用下与套管接触,在附加应力作用下油管上下移动,不断磨损,最终穿孔断裂。

The fracture causes of a tubing was studied through analysis of fracture characteristics,material properties and load,combined with service environment and operation conditions.The results show that the sulfur content in oil tubing exceeded the standard,but content of other elements,microstructure and mechanical properties of the fractured tubing met the standard requirements.It was found that the fracture was characterized by ductile fracture without obvious corrosion from the analysis of fracture characteristics.According to the load calculation,when there was a leakage point in the casing near the fractured tubing,a pressure difference between the annulus and the formation formed.The tubing contacted with the casing under the action of pressure difference,and was worn constantly by moving up and down under the action of additional stress.Finally it was perforated and fractured.