Performance of wellbore cement under acetogenic conditions: Degradation mechanisms and the role of microsilica in enhancing the cement sheath integrity for underground hydrogen storage

Abstract

Underground hydrogen storage (UHS) relies critically on the long-term integrity of wellbore cement, yet hydrogen-driven microbial processes can generate acetic acid, that threaten the performance of cement sheath. This study examines the chemical–mechanical degradation of API Class G cement exposed to acetic acid and evaluates whether microsilica can enhance resistance under such conditions. Cylindrical specimens of cement blends and cement-shale composite specimens with neat Class G and Class G with 10 wt% microsilica replacement were cured for 28 days and then immersed in acetic acid solutions (10% and 20% by volume) for a further 28 days. These concentrations represent accelerated, boundi..