Core-To-Field Scale Numerical Modeling of CO2-EOR and Storage in a Tight Carbonate Reservoir of the Volga-Ural Basin

Abstract

Depleted tight-carbonate reservoirs are attractive targets for coupling CO2-enhanced oil recovery (CO2-EOR) with geological storage, yet the low viscosity of supercritical CO2 and pronounced permeability contrasts drive early breakthrough and poor sweep. Pre-generated CO2 foam suppresses gas mobility and diverts flow toward bypassed zones, but field implementation will require a demonstration of effectiveness from the laboratory to field scale. This work implements a mechanistic, reaction-based foam formulation (a kinetic network for lamella generation, trapping, decay, and remobilization) within a pseudo-compositional simulator and applies it across scales for a tight carbonate of the Volga-Ural Basin. The model was calibrated by simultaneous history matching of oil recovery, differential pressure, and produced-CO2 fraction from a single-surfactant CO2-foam core flood, cross-validated without further tuning against an independent pure-CO2 flood and then transferred to larger scales without retuning. Long-core simulations indicate that permeability heterogeneity reduces sweep and accelerates CO2 breakthrough in pure CO2 injection, whereas CO2-foam mitigates channeling via lamella-induced mobility control and yields oil recovery that is comparatively insensitive to heterogeneity. At reservoir scale, continuous CO2-foam injection increased cumulative oil recovery by approximately 8 percentage points relative to continuous CO2 injection and improved CO2 retention by reducing early gas channeling, but CO2-foam propagation remained largely near-wellbore (approximately 25–50 m from the injector) due to kinetic decay under field-scale flow conditions. A hybrid strategy (15 years water injection followed by 35 years CO2-foam) increased final recovery by a further 3 percentage points relative to continuous CO2-foam injection, consistent with reduced oil-induced foam destabilization in the near-well region. The study demonstrates that reaction-based foam modeling can provide a physically consistent framework for evaluating mobility control and CO2 retention in tight carbonates, while highlighting the need for further validation of kinetic scaling and uncertainty quantification prior to field application.