Study of convective-diffusive flow during CO2 sequestration in fractured heterogeneous saline aquifers

Abstract

CO2 sequestration in naturally fractured saline aquifers is important to be studied. This paper investigates the convective-diffusive flow to study CO2 sequestration by dissolution in single and multi-fractured heterogeneous saline aquifers. The effect of fractures density, orientation, permeability, aperture and surface roughness on CO2 dissolution and propagation of density-driven fingers are investigated. The results indicate that a single fracture causes the growing density fingers to deviate towards the high permeability path of the fracture. Additionally, the higher vertical fracture orientation, aperture and permeability will lead to a higher CO2 storage. In the multiple fracture systems, matrix permeability has a dominant and positive effect on CO2 storage. Nevertheless, the effect of fractures properties such as fracture density, spacing, permeability, aperture and surface roughness on the CO2 storage are dependent on the fractures orientation. For instance, having fractures with rough surface can cause CO2 dissolution retardation in the aquifers with only vertical fractures. This study provides more insights into dissolution trapping of CO2 in fractured heterogeneous saline aquifers.