Numerical investigations on sc-CO<inf>2</inf>gas sequestration in layered heterogeneous deep saline aquifers

Carbon capture and storage (CCS) technology is regarded as the feasible solution to mitigate CO2 emissions from the burning of fossil fuels in large-scale industries to meet energy demand. The storage of CCS requires the injection of CO2 gas captured from bulk sources into geological formations. Deep saline aquifers are the largest identified storage potential formations for injecting high volumes of gas. The safe storage of CO2 gas requires a better understanding of the gas migration and pore pressure buildup in the aquifer. In the present work, a numerical has been developed to study the various factors impacting the CO2 gas migration in the formation of both homogeneous and multi-layered deep saline aquifers. The numerical model has been history matched with an analytical solution and the plume thickness data reported by Nordbotten, J. M., M. A. Celia, and S. Bachu. (2005). "Injection and Storage of CO2 in Deep Saline Aquifers: Analytical Solution for CO2 Plume Evolution during Injection."Transport in Porous Media 58 (3): 339-60. The saturation distribution and pressure buildup in the aquifer are different for each case. The relative permeability of gas increases in the homogeneous case. The drainage efficiency increases along with injection time in any formation. However, the drainage process is less in layered formation compared with homogeneous formation. The parameterized storage efficiency factor (Ɛ) is calculated to understand the storage capacity of the aquifer along the lateral direction near to injection well. The formations having low permeability in the top and below layers of the aquifer, the storage efficiency factor is high indicating more amount of gas is stored.