Convective dissolution in layered porous media with application to CO2 geological sequestration: Experimental and numerical insights into layering configuration and interface angle

Convective dissolution is crucial for the secure and permanent sequestration of CO2 within deep saline aquifers. Despite the prevalence of inclined stratified formations at potential sequestration sites, there is a lack of systematic investigations about the combined effects of layering configurations and inclination angles on convective dissolution. This study endeavored to bridge this gap by conducting a series of laboratory experiments complemented by numerical simulations. The aim was to elucidate the impact of various inclination angles on convective mixing within diverse stratified structures. Our findings revealed that within stratified formations, phenomena such as finger accumulation and enhanced finger merging at decreasing-permeability interfaces co-occurred with typical fingering patterns in homogeneous media. Additionally, an amplified shielding effect was observed in increasing-permeability formations. Within our research scope, a more significant permeability contrast between layers was found to result in more pronounced variations in convective dissolution characteristics, without altering their inherent pattern. Inclined interfaces within stratified formations were found to further intensify the accumulation of leading fingers at decreasing-permeability interfaces and to facilitate penetration across increasing-permeability interfaces, with these effects being more pronounced at steeper angles. In our study, the average mass flux at interface was considerably higher in configurations with decreasing permeability, diminishing as the interface angle increased. These findings suggest that in practical carbon geological storage applications, employing layers with decreasing permeability and less steep interface angles, coupled with a higher permeability contrast between layers, could enhance the efficiency of dissolution sequestration within inclined stratified layers. This study provides critical insights into the optimization of carbon sequestration strategies within inclined, multi-layered saline aquifers, highlighting the importance of layer configuration and interface geometry in the convective dissolution process.