Convective Mixing Driven by Non-monotonic Density

Abstract CO $$_\text {2}$$ 2 injection for enhanced oil recovery (CO -EOR) or storage in depleted and gas reservoirs can be a means disposing of anthropogenic emissions to mitigate climate change. Fluid flow mixing hydrocarbons such systems are governed by the underlying physics thermodynamics. Gravity effects as gravity override convection mechanisms that alter fluid dynamics, impacting migration, production eventual at field scale. This study focuses on miscible setting caused non-monotonicity density when mixed with , i.e., maximum mixture occurs an intermediate concentration. We perform high-resolution simulations quantify convective behavior simple box system where isolated. show is dependent whether originates from above below zone. From above, follows classic but accelerated viscosity decrease increasing . below, flows upward due buoyancy, countered downward heavier density. significantly more complex efficient than above. characterize instabilities both early- late-time regimes rates. For 100 mD reservoir, fingers would order centimeters width mix over meter length scale within days month, depending placement The performed non-dimensional form thus rescaled different reservoir parameters. Our results give important insights into field-scale impacts guide future work development upscaled models experimental design.