The feasibility of enhanced pore space utilization in CO2 storage reservoirs using an artificially emplaced Si-gel flow barrier

Abstract

Carbon capture and storage is a key technology to abate CO₂ emissions. One of the challenges towards ensuring the efficiency and the security of CO₂ storage in reservoirs, such as open saline aquifers, is the low pore space utilization. This study investigates the feasibility of using an artificial Si-gel barrier to enhance pore space utilisation in such reservoirs under variable geological conditions. Conceptually, enhanced CO₂ capillary trapping is achieved by emplacing a disk-shaped, low-permeability barrier above the CO₂ injection point forcing the injected CO₂ to migrate laterally underneath the barrier before transitioning to buoyancy-controlled migration. Multiphase fluid flow simulations were conducted to test the feasibility of this concept. Sensitivity analysis revealed that the barrier exhibits a strong control on CO₂ plume geometry. Specifically, the relative impact of the barrier diameter on increasing the CO₂ plume width, reducing the plume height and enhancing trapping varied between 67 and 86%. Capillary trapping was enhanced by 40-60% with a 20 m increase in barrier diameter in low permeability reservoirs. Additionally, the results indicate that the barrier can enhance the security of trapping CO₂ in high permeability reservoirs. Results were tested for the South-West Hub reservoir, a case study area in Western Australia.