51314-4299-Impact of Oxygen Ingress in CO2 Corrosion of Mild Steel

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Product Number: 51314-4299-SG

ISBN: 4299 2014 CP

Author: Nor Roslina Rosli

Publication Date: 2014

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The development of Carbon Capture and Storage (CCS) technologies have enabled the success of CO2-EOR injection operations as in the case of the IEA GHG Weyburn-Midale CO2 Monitoring and Storage Project. However captured CO2 from anthropogenic sources is impure and can potentially contain oxygen. A preliminary study was conducted at low pressure to investigate the effect of oxygen ingress on the iron carbonate (FeCO3) corrosion product layers in mild steel CO2 corrosion. Carbon steel (AISI 1018) samples were immersed in a CO2 saturated 1 wt.% NaCl electrolyte for 7 days with the perturbation of 1 ppm oxygen at different duration of the experiments. Iron carbonate film-forming conditions (80°C and pH 6.6 ± 0.1) were maintained throughout the experiment. Electrochemical measurements indicated increased corrosion rates over the first two days of oxygen exposure with a decrease in corrosion rate thereafter due to scale formation that conferred some degree of protection to the steel surface. On the other hand when oxygen was introduced after carbonate scale formation the corrosion rate did not increase. Although the corrosion rates at the conclusion of all tests were relatively low localized corrosion was observed. Surface analysis using SEM EDS XRD & Raman confirms the formation of iron (III) oxides and FeCO3 and its morphologies. A distinct feature of oxygen ingress is the formation of tubercles on steel surface. The degradation of initially formed iron carbonate occurred concurrently with the development of localized corrosion features as deep as 100 µm. It can be concluded that oxygen ingress even at low concentrations can have a profound effect on sweet corrosion of mild steel.