Coupled Numerical Simulation of CO2 - EOR Flooding: Integrating Multiphysics Interactions

Numerical simulation of CO2-enhanced oil recovery (CO2-EOR) critically advances hydrocarbon field development by quantifying multiphase saturation dynamics during CO2-driven displacement. This study establishes a cylindrically configured 1D triple-phase mathematical model integrating Darcy's law and mass conservation principles, employing an implicit pressure-explicit saturation (IMPES) finite-difference scheme to resolve spatiotemporal evolution of aqueous, oleic, and gaseous phase saturations. Systematic incorporation of chemical reaction kinetics, viscosity-pressure coupling, and dynamic relative permeability effects yields a novel computational framework for immiscible displacement analysis. Simulations reveal two governing mechanisms: 1) CO2-saturated fluid/rock interactions induce pore-throat dilation, amplifying effective flooding radii; 2) Wellbore-formation pressure differentials (ΔP) dictate CO2 plume propagation, where elevated ΔP expands repulsion radii and oil displacement annulus thickness. Paradoxically, increased reservoir porosity reduces annular confinement while diminishing displacement efficiency despite enhanced volumetric throughput, with simulations confirming persistent oil-rich annuli characteristic of non-miscible regimes. These findings provide actionable guidelines for optimizing CO2-EOR injectivity parameters and ensuring long-term carbon sequestration integrity in heterogeneous formations, bridging theoretical modeling with field-scale implementation strategies.