Sensitivity of various forms of CO2 sequestration to different parameters in saline aquifers in the Fushan depression based on numerical simulation

CCUS is an effective approach for mitigating greenhouse effects. Saline aquifers are suitable for CO2 sequestration due to widespread distribution and large potential. The Fushan Depression possesses abundant saline aquifers but has been underexplored for CO2 sequestration. Unlike other regions, the unique tropical location characterized by high temperature and pressure, makes it unsuitable to directly apply existing research results. This study aims to fill this gap by developing a two-dimensional model, which incorporated four mechanisms and was subjected to comprehensive sensitivity analyses of aquifer physical properties, water properties, and operational parameters. Additionally, the impact of heterogeneity was analyzed. Simulation results reveal that temporal variation of sequestration vary across different mechanisms, and are influenced by distinct physical properties. Increased water salinity enhances sequestration, except for dissolved and mineral trapping. A threshold exists for bottom hole pressure and injection rate. The injection location determines the dominant sequestration, while well types affect specific mechanisms. The presence of fractures alters CO2 migration pathways, potentially impacting sequestration efficiency. Field research indicates that low-permeability caprocks enhance sequestration when target layers are deeply buried. This study provides guidance for selecting appropriate formations and injection methods to ensure efficient and secure sequestration in regions with similar tropical conditions.