Failure Analysis on Cracking Leakage of a Tubing in one Well

The ϕ73 mm×5.51 mm P110 tubing in a well cracked longitudinally during acidification operation. By means of macro examination, chemical composition analysis, mechanical property test, metallographic analysis and scanning electron microscope fracture analysis, the cracking reasons of the tubing were analyzed. The results show that the wall thickness of the tubing was reduced greatly because serious uneven wear happened to the inner wall during oil production, which made the tubing not withstand the test pressure of acidification operation, so ductile cracking occured at the thinnest wall thickness position of the uneven wear groove. Finally, the measure of using partial abrasion protector during oil production was proposed.