Pore-Scale Evolution of Carbonate and Sandstone Reservoirs Under CO 2 –Brine Interaction: Implications for Sustainable Carbon Storage

The rise in atmospheric CO 2 intensified the urgency for carbon capture and storage (CCS), yet uncertainties remain in predicting evolution of reservoir properties under CO 2 injection. This study investigates how CO 2 –brine–rock interactions alter porosity and permeability in carbonate and sandstone reservoirs. We quantify pore-scale changes and effects of CO 2 -saturated brine on rock. In calcite-rich carbonates, CO 2 -induced acidification enhances permeability through selective dissolution. Dolomite-rich samples and sandstones exhibit suppressed permeability response due to slower dissolution and pore clogging. μCT and SEM reveal that although bulk porosity changes are small, local changes—especially formation of micropores and mineral occlusions—substantially influence permeability. Geochemical modeling confirms three-stage evolution: early dissolution, intermediate buffering with onset of precipitation, and long-term mineral trapping with near-steady porosity. The results indicate that early injectivity gains may be temporary and that proactive monitoring and management are required to safeguard long-term storage integrity. The findings provide actionable insight for sustainable CCS design, risk assessment, and reservoir stewardship.