Influence of capillary force heterogeneity and geochemical raction on CO2 flow and trapping

To safely store CO₂, it is necessary to accurately predict the behaviors and trapping evolution of CO₂ in saline aquifers. However, due to the heterogeneity of actual saline aquifers, the evolution of CO₂ plume and accompanying trapping are still unclear during and after injection. Although prior studies have highlighted the impact of capillary entry pressure heterogeneity on CO₂ plume and trapping, the role and influence of CO₂-induced geochemical reactions are still not fully understood. Therefore, the main objectives of this work are to study the evolution of CO₂ plume and storage under heterogeneous capillary entry pressure and geochemical reactions. To illustrate the evolution, a comprehensive CO₂ migration and storage model under heterogeneous capillary entry pressure and geochemical reactions is done to study CO₂ behavior in detail. The results showed that heterogeneous capillary entry pressure in the saline aquifer can hinder the upward migration of CO₂, causing it to redirect and increase its lateral volume. The geochemical reactions can reduce porosity by 10^-4 and permeability by 1 mD within 100 years and hinder CO₂ migration in all directions. The capillary entry pressure magnitude, its heterogeneity, and lateral correlation length are the main parameters affecting the evolution of CO₂ storage. Their increase can greatly limit CO₂ vertical migration rates and decrease dissolution and mineral trapping amount but may double local capillary trapping amount. In contrast, the increase in temperature and the ratio of vertical/horizontal permeability favors CO₂ vertical migration, dissolution, and mineral trapping amount. Therefore, to ensure the long-term safety of CO₂ storage, it is necessary to select a suitable heterogeneous reservoir.