Cause Analysis on Fracture of Tubing Joint in an Oil Well

Fracture failure of a tubing joint occurred in an oil well after production for 11 months. Through the macroscopic and microscopic morphology observation, microstructure analysis, mechanical property test and chemical composition analysis to the fractured tubing joint, the fracture reasons were found out. The results show that the fracture of the tubing joint was mainly caused by multi cracks stress corrosion cracking on the inner wall of the tubing joint under the production conditions of the oil well. Then under the interaction of corrosion and mechanical loads, the cracks continuously extended and connected with each other, and when the cracks penetrated the wall thickness of the tubing joint, they showed corrosion fatigue cracking, which eventually led to the fracture failure of the tubing joint. Improper processing technology of the tubing joint increased the probability of fracture failure.