Experimental Drainage Dynamics Study of Supercritical CO2 and Water in Low-Permeability and Heterogeneous Rocks

Flooding experiments with deionized water and supercritical CO2 were conducted at 40 °C and greater than 8 MPa pressure on two cores, a low-permeability sandstone and a heterogeneous carbonate specimen, obtained from rocks outcropping in the Erdos Basin. Located in the northern China, the Erdos Basin has a prospective potential for large- scale CCS deployment. The drainage dynamics were investigated by using transient inlet and outlet pressures and transient flow rates of outflowing supercritical CO2 and water. We observed very different drainage dynamics and high residual water saturations that were interpreted as the combined results of: i) the low permeability of the solid specimens, ii) the large difference in viscosity between CO2 and water, iii) the non-uniform displacement of pore fluids caused by sub-core heterogeneity.