Pore-scale Considerations on Ostwald Ripening in Rocks

Abstract

Residually trapped CO₂ is often assumed to be stable when simulating its long-term fate in geological storage reservoirs. Ostwald ripening is a mechanism that could potentially cause remobilization. We compare the case of bubbles of gas in a free liquid to that of a solid porous matrix. Using a new continuous pore network model, we gain insights on Ostwald Ripening in rocks and estimate time scales of evolution of multi-ganglia systems. Evolution is found to be highly dependent on system initialization as well as on pore structure. For residually trapped CO₂ in homogeneous rocks, a stable equilibrium is conceptually possible.