Deformation of a Carbonate-Clayey Caprock Exposed to an Acidic Solution

Permanent subsurface storage of CO2 is a cornerstone technique for the global mitigation of atmospheric emissions. To ensure the long-term integrity of storage sites, this study investigates the geochemical interactions between pore fluids and caprock formations, focusing on the evolution of caprock’s deformation. Experimental reactive transport tests, conducted at the Geotechnical Laboratory of Politecnico di Torino on carbonate–clayey specimens, provide key insights into the mechanical response and time-dependent strain evolution under acidic conditions. By integrating Mercury Intrusion Porosimetry and void ratio measurements, the research characterizes the microstructural changes and fabric collapse occurring within the rock matrix. Furthermore, X-Ray Diffraction analysis and geochem-ical numerical modelling elucidate how global reduction of carbonate content, governed by H+ transport mechanisms (diffusion versus advection), shapes the caprock’s deformation.