Cause Analysis on Fracture of a Repaired Tubing in a Gas-Lift Well

The fracture reasons of a repaired tubing in a gas-lift well in Tarim oilfield were analyzed through mechanical and chemical property testing, SEM analysis and EDS analysis. The results show that the chemical compositions and mechanical properties of the repaired tubing met the requirements of the relevant standards for the P110 steel grade tubings. The fracture of the tubing was due to the many cracks on the internal surface of the tubing which generated under the co-action of corrosive fatigue and stress corrosion cracking and reduced the bearing capacity of the tubing.