Autor: Iman Rahimzadeh Kivi. PhD Candidate
Assessment of CO 2 leakage risk within basin-scale CO 2 storage in multi-layered sedimentary basins.
Hundreds of gigatonnes of CO 2 will need to be stored in deep geological formations in the upcoming decades to mitigate climate change. Success in the massive deployment of geologic CO 2 storage depends primarily on the selection of geological settings through which minimal CO 2 leakage toward the surface could take place. Here, I present numerical simulations that allow for understanding the leakage risk from basin-scale CO 2 storage sites over geological time scales (million years), much longer than what had been investigated so far. The model accounts for the vertical two-phase flow of CO 2 and brine and diffusive transport of aqueous CO 2 through multi- layered geological settings. I argue how this model enables us to reliably capture the dynamics of basin-wide vertical CO 2 migration at affordable computational costs. Based on the obtained results, I discuss the effects of geological configurations, caprock thickness, and its notably scale-dependent transport properties on the leakage risk. I conclude that a high-frequency layering of aquifers and caprocks, even if pervasively fractured and a few tens of meters thick, will build confidence in the permanent containment of CO 2 in the subsurface.