Research on CO2 sequestration in saline aquifers with different relative permeability considering CO2 phase conditions

Abstract

Saline aquifers are the most feasible potential site for the storage of CO₂. The behavior of CO₂ in different phase states may significantly affect the flow properties and sequestration efficiency. It is important to understand and predict the effects of different CO₂ phases. This study conducted relative permeability tests under two experimental conditions with CO₂ in different phases. Incorporating experimental data into reservoir-scale simulations to analyze the effects of different phases of CO₂ on structural, solubility, and residual sequestration mechanisms, and to predict CO₂ behavior in saline aquifers. The results show that the CO₂ relative permeability and residual CO₂ saturation are high under supercritical conditions. It is more favorable to consider the relative permeability and hysteresis effects on the supercritical CO₂ results, with a more dispersed distribution of CO₂ at the bottom of the reservoir. There was a significant difference in residual sequestration, with the gaseous group showing a 14.16 % reduction in residual sequestration and a 4.27 % reduction in total sequestration compared to the supercritical group. The ratio of structural sequestration, solubility sequestration, and residual sequestration in the total sequestration in this study is about 50 %:30 %:20 %.