Corrosion Failure Causes of Surface Oil Pipe in an Overseas High-sulfur and High-salt Oilfield

Corrosion failure of oil pipelines in a high-sulfur and high-salt oilfield was analyzed by means of chemical composition and microstructure analyses, microbiological detection of produced water, as well as corrosion morphology observation and corrosion product analysis using SEM, EDS, XRD etc. The results show that microbiological-induced corrosion (MIC) was the main reason of corrosion leakage of the pipeline. The oil production lower than expection resulted in low flow rate of the crude oil in the pipeline, the water cut was higher than expection. And the pipeline was not cleaned in time after the production, causing free water to precipitate at the bottom of pipeline. All of these created favorable conditions for the breeding and reproduction of sulfate reducing bacteria (SRB) and thus led to corrosion failure of the pipeline. H₂S, CO₂ and Cl^- in the corrosive medium jointly participated in the corrosion process.