Effect of Ostwald ripening on CO₂ residual trapping

The long-term reliability of residual trapping is a key process for CO₂ storage security and efficiency. After an initial drainage phase during injection, substantial supercritical CO₂ (scCO₂) volumes are disconnected from the plume during brine imbibition. Whereas conventional multi-phase flow models assume that residually trapped portions of the plume are permanently immobilized, multiple physiochemical mechanisms exist which could potentially invalidate this assumption. One mechanism is CO₂ transfer driven by differences in capillary pressure between disconnected neighbor ganglia, called Ostwald Ripening. The aim of this work is to investigate the effect of Ostwald ripening on the long-term evolution of residual trapping by i) assessing the potential for Ostwald ripening in rocks to remobilize trapped CO₂ using synchrotron X-ray microtomography (micro-CT) analysis of pore-scale capillary pressure and modeling of Ostwald ripening mechanism in rocks and ii) observing the stability of residually trapped scCO₂ during the early stages following imbibition CO₂ in a sandstone by conducting a drainage-imbibition experiment with reservoir conditions and time-resolved micro-CT imaging.