Electrochemical Testing to Determine the Critical Pitting Temperature in Supercritical CO2 and Brine Using a Modified ASTM G150 Test Procedure

Abstract There continues to be insufficient corrosion data for many alloys being considered for casing and tubing in carbon capture and sequestration (CCS) injection wells. The performance limits of corrosion resistant alloys (CRAs) are not well established in such CCS environments. In the absence of industry standards, injection well completion equipment frequently considers using 13Cr (UNS S42000) and Super 13Cr (UNS S41426) martensitic stainless steels based on years of good experience in oil and gas production. Recent studies and test programs have indicated that these alloys are far more limited in CCS. In prior work, an electrochemical technique was developed to rapidly screen alloys in a simulated environment consistent with water condensing from a supercritical CO2 injectate. A similar electrochemical study was performed to explore how 10,000 ppm to 100,000 ppm chlorides in the formation brine affects the critical pitting temperatures (CPTs) of plain and modified 13Cr alloys using a modified ASTM G150 test method to simulate CCS environments. This approach is intended for fast determination of the risk of pitting for CRAs to augment the need for longer term high pressure autoclave tests.