Modelling of CO2 Sequestration in Deep Saline Aquifer Reservoir using Surface Evolver Software

Abstract

A strategy to mitigate CO2 concentration in the atmosphere is injection of supercritical CO2 in porous sedimentary medium filled with saline water where CO2 gets trapped in the pores. Sequestration is resultant of two processes, drainage and imbibition in accordance with capillary law. Simulation of the pore-scale trapping has been performed on reservoir scale. A simple model reservoir consisting of 1000 tetrahedral subunits was constructed. Using Surface Evolver software, pore volueach subunit. The CO2 pressure and liquid saturation curves of the reservoir displayed hysteretic character, indicating that the evolution of the system is pathway-dependent. The simulated curves illustrate the pathway dependency of the residual gas saturation, an important parameter controlling the amount of CO2 stored in the reservoir, hence the efficiency of the CO2 storage. Our study also shows the existence of critical thresholds in terms of in/out gassing during the drainage or imbibition processes