oa CO2 Migration and Trapping Behavior in a Heterogeneous Media: Core- and Pore-scale Study

Understanding the migration of CO2 and water in complex geologic media is crucial for ensuring the safety and long-term efficacy of CO2 geological storage. Geologic heterogeneity has a significant effect on multiphase flow properties as well as CO2 trapping mechanisms. This study investigates CO2 migration and trapping mechanisms in heterogeneous geological media utilizing X-ray imaging technique. Both the core- and pore-scale multiphase flow experiments were conducted using a sandstone with sedimentary lamination. At the core scale, capillary heterogeneities influenced CO2 displacement, with higher initial saturations widening the residual trapping distribution. New flow regimes during dissolution were identified, and a scaling relationship for their temporal evolution was proposed. Pore-scale analysis revealed micro-scale heterogeneities impacting CO2 flow dynamics, with spatial variation in capillary entry pressure leading to non-uniform flow. In-situ imaging captured CO2 cluster breakup and local imbibition processes. These findings enhance our understanding of multiphase flow in heterogeneous porous media, and our study underscores the importance of considering both core- and pore-scale heterogeneities for CO2 geological storage.