Corrosion Resistance of CRA for CCS Applications under O2, SO2 and Practical Mixed Gas Conditions at Different Chloride Levels

Abstract In carbon dioxide capture and storage (CCS), CO2 emitted from various industrial sources, for example fossil-fuel power plants, is captured and injected into the subsurface in a dense or supercritical phase through injection strings. This transported CO2 may contain impurities, such as SOx, NOx, O2. To evaluate the corrosion resistance of CRAs for injection tubing in supercritical CO2 with O2, SO2, and practical mixture of gases, corrosion tests were performed under conditions in 5, 15 and 25 wt% NaCl solutions saturated with CO2. Corrosion resistance of Super Martensitic Stainless Steel (UNS S41426), Duplex Stainless Steel (UNS S82551), and Super Duplex Stainless Steel (UNS S39274) were evaluated. In the case of CO2 with O2 as a contaminant, each material showed different applicable limits with O2 level in 5 wt% NaCl solution under high pressure CO2. On the other hand, only S39274 showed good corrosion resistance up to 0.02 bar O2 in the 25 wt% NaCl solution. In the case of CO2 with SO2, S41426 showed no applicable region even in 5 wt% NaCl solution due to its de-passivation. S39274 showed a narrow range of acceptable limits even in a 25 wt% NaCl solution in terms of crevice corrosion. For mixed gas conditions, S39274 showed good corrosion resistance in most of the conditions. These results be highly dependent on the chloride concentration levels and the total pressure of CO2, meaning the partial pressure of various impurities. Additionally, the effect of oxidants such as NO2 and O2 decreased in mixed gas conditions. Overall, it is considered that S39274 is suitable material for CO2 injection system with practical level of contaminants even if formation water flow back occurs.