Failure Analysis of Cracked and Corroded Tubings in Sudong Block of Changqing Oilfield

Abstract

In the process of layer inspection and hole mending, it was found that the corrosion of tubing in a well was serious, and perforation and fracture occurred. Part of the tubing was found to be cracked from the failed pipe samples, and relatively serious pitting corrosion pits were found on the surface of the outer wall. The fracture morphology and corrosion products were analyzed by means of macroscopic analysis and metallographic microscope, SEM and EDS. The result show that the mechanical damage of the outer wall of the tubing was the primary condition for accelerating corrosion, and the severe corrosion thinning of the inner and outer walls of the tubing was the main reason for the failure of the tubing string. The corrosion perforation of tubing was mainly caused by internal corrosion.