Benchmarking Study of Sour Cracking Behavior in CCS Well Injection Systems

Corrosion and materials performance are key considerations in the practical design and operation of Carbon Dioxide capture and storage (CCS) systems. Materials resistance to H2S-related cracking is a mature area with guidance provided in NACE MR0175/ISO 15156. However, dense phase CO2 in equilibrium with free water results in extremely low pH values, below typically evaluated regions of sour performance. Benchmarking study of sour cracking behavior in CCS environment is required with the focus on wells high strength materials. In the study, thermodynamic calculation of H2S level in both CO2 rich phase and H2O rich phase with different conditions is performed. A series of tests is designed per thermodynamic calculation and performed in a state-of-the-art lab. This study to check if SSC resistance in highly buffered pH 3.5 conditions, NACE TM0177 Solution B, is equivalent to lower pH CCS conditions with regards to both SSC initiation and propagation as evaluated by constant deflection specimens and double cantilever beam (DCB) specimens, respectively.