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.