Failure Analysis on the Corrosion Perforation of N80 Oil Pipe in an Offshore Water Injection Well

Abstract

In this paper, the cause and mechanism of local corrosion perforation under the bottom water regulator of an offshore water injection pipe string were analyzed by means of macro analysis, physical and chemical properties analysis, metallographic analysis, XRD analysis, SEM micro morphology analysis, energy spectrum analysis, water content and bacteria test, and finite element analysis and other methods, combined with the actual site conditions. Results showed that the internal corrosion perforation of the oil pipe was caused by bacterial corrosion under the scale, and the high Cl- in the residual acid after acidizing operation accelerated the local corrosion perforation. Based on this, it was suggested to regularly add chemicals and use corrosion-resistant pipes to prevent early corrosion perforation failure of oil pipes.

Keywords

• water injection well|bacterial corrosion|local corrosion perforation|the bottom of pipe string