TESTING OF OCTG MATERIALS IN SIMULATED CCS ENVIRONMENTS: COMPARING DIFFERENT APPROACHES FOR IMPURITY CONCENTRATIONS DEFINITION (C2026-00202)

Maria Cancio, Jazmin Poliseno, Martin Emiliano Valdez, PRIYANKA ADAPALA, Xi Wang, Yoon-Seok Choi

The underground injection of dense-phase CO₂ containing impurities for carbon capture and storage (CCS) applications poses potential risks to the integrity of downhole materials, particularly under conditions that may allow the presence of liquid brine. Testing materials for these environments remains challenging due to its complexity and the lack of standardized methodologies. Typically, materials are exposed to simulated CCS environments in autoclaves containing brine in contact with dense-phase CO₂ being the incorporation of impurities one of the main challenges.
This paper compares two approaches for the impurities addition into the autoclave during experimental testing. In the first approach, impurities were added based on the nominal composition of the CO₂ stream. In this case, dissolution into the brine and chemical reactions among impurities will alter the actual composition of the CO₂ phase. In the second approach, the amount of each impurity was adjusted to achieve target concentrations in the CO₂ phase after accounting for dissolution and chemical interactions.
Materials such as Martensitic Stainless Steels—that are susceptible under the low pH that can develop during CO₂ injection—were evaluated under both scenarios. This paper describes the relative severity of each experimental approach and prompts further discussion on the need for standardized testing methodologies.