Failure Analysis of Fractured Tubing

A P110 oil tubing of oil well fractured in stretching process. The fracture reasons of the P110 tubing were analyzed by means of chemical composition analysis, mechanical performance test, metallographic examination and corrosion product analysis. The results showed that the dissolved oxygen in formation water caused corrosion on tubing surface and pitting appeared in some locations. At the same time, tubing thickness reduced and capacity declined because of corrosion. So cracking appeared and the P110 tubular fractured.