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

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.