Capillary Pressure and Relative Permeability Model Uncertainties in Simulations of Geological CO₂ Sequestration

Precise descriptions of saturation, capillary pressure and relative permeability s-p_c-k_r relations are essential for predictions and simulations on multiphase flow system. The primary object of this work is to investigate their influence on geological CO₂ sequestration processes. Five types of commonly used s-p_c-k_r relations are examined in this study. Simulation results show significant influences of s-p_c-k_r relations on 1) the location and saturation of displacement fronts, 2) buoyancy driven migration speed, 3) horizontal spreading distance and the rate of dissolution of supercritical CO₂. The effects of capillary pressure on the horizontal spreading of supercritical CO₂ plume and its dissolution rate was resolved in this study for the 1st time in literatures. Simulation results of subsurface CO₂ storage suggest that that careful selection of s-p_c-k_r relations and calibration methods are essential for accurate predictions.