Visual investigation of CO2 dissolution and convection in heterogeneous porous media at reservoir temperature and pressure conditions

Abstract

CO2 convective mixing in saline aquifers has been widely studied numerically and experimentally. Reservoir heterogeneity is significant for CO2 convective mixing and experimental studies are still limited. In this study, we have conducted a visualization of CO2 convective mixing experiments in heterogeneous porous media at reservoir conditions using CO2 and water. We have used a two-dimension Hele–Shaw cell, different glass beads of different permeability at porous media, and water solution with pH indicator. Glass beads were packed in a different way (horizontally and vertically) to generate the heterogeneity inside the test cell. We have studied transport velocity deviation due to the heterogeneity and effects of permeability transition zone together with the effects of boundary conditions. It was found out that having a low permeable layer below a high permeable layer restructure the flow of CO2 fingers and dampens the CO2 transport velocity. With the vertical permeability zones, having a high permeability zone accelerates CO2 gravity transport through that zone which is a good representation for a fracture or a fault in the reservoir. CO2 convection onset is governed by the vertical high-permeable layer. Boundary conditions have been dominant with the presence of high permeable zones. It also found out that the experimental results presented in this study match with the simulation studies that are available in the literature.