Impact of mineral deposits on CO2 corrosion of carbon steel

Abstract

The present study describes the impact of mineral deposits (SiO2, Al2O3 and CaCO3) on CO2 corrosion of 1030 carbon steel in chloride-containing environment. The corrosion process was investigated using electrochemical and weight loss measurements, followed by surface analysis of the corroded steels conducted by visible light and scanning electron microscopy. It was found that the extent of the corrosion damage is directly related to the nature of the mineral deposits and significant differences were observed in the morphology of the surfaces corroded in the presence/absence of different deposits. The susceptibility of the deposit- covered steels to the localized corrosion and the influence of deposits on corrosion inhibition are also discussed and related to the properties of the deposits. The inhibitor performance at deposit covered steels varied according to the chemical composition of the inhibitor and the nature of the deposit. The study serves to improve the understanding of CO2 corrosion process in the presence of solid deposits and the findings can be applied to address the under-deposit corrosion in oilfield operations.