Localized corrosion in sour fields is a challenge persisting in the oil and gas industry since it has frequently been seen as a cause for catastrophic failures of upstream pipelines. Hence, prediction and mitigation of H2S localized corrosion of mild steel is of key importance for integrity management. However, our current understanding of H2S localized corrosion mechanism(s) from numerous studies in both in the laboratory and the field is far from being conclusive. Especially, the environmental conditions that may cause localized H2S corrosion are unclear. Therefore, defining an experimental condition in the laboratory that can replicate localized corrosion in a sour environment is critical to our understanding of mechanisms of localized corrosion. The focus of the present research was to explore environmental conditions leading to localized H2S corrosion. It was found that severe localized corrosion was repeatedly observed in experiments, when there was a simultaneous formation of greigite and/or pyrite. Based on those experimental results, a hypothesis for a mechanism of H2S localized corrosion was proposed.

Subject
X-ray diffraction, Steel surfaces, Mackinawite, Corrosion rate, Profilometry, Iron sulfides, Pyrrhotite, Surface morphology, Corrosion products, Pyrite, Surface layers, Steel, Localized corrosion
Keywords:
Hydrogen sulfide, localized corrosion, iron sulfide, polymorphism
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2016
Association for Materials Protection and Performance (AMPP)
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