Chemo-hydro-mechanical effects of CO2 injection into a permeable limestone

Research demonstrates that CO2 injection into carbonate aquifers, such as the Pont du Gard Limestone, significantly alters rock properties due to acid-producing reactions. The study found that HCl solutions cause localized, compact dissolution at the core inlet, affecting hydromechanical properties, while CO2-saturated water leads to widespread chemical reactions along preferential flow pathways, enhancing permeability through wormhole formation. A power-law relationship with a high exponent (up to 24) describes the permeability-porosity variation, and altered cores exhibit reduced mechanical strength and ultrasonic velocities, validated by a Differential Effective Medium approach. These findings highlight the complex chemo-hydro-mechanical effects of CO2 storage in carbonates, crucial for improving predictions and monitoring of storage performance.

Vafaie, A., Cama, J., Soler, J. M., Grgic, D., & Vilarrasa, V. (2023). Chemo-hydro-mechanical effects of CO2 injection into a permeable limestone. International Journal of Coal Geology, 278, 104359. https://doi.org/10.1016/j.coal.2023.104359