Numerical and analytical study of effects of small scale heterogeneity on CO₂/brine multiphase flow system in horizontal corefloods

Here we provide a comprehensive study of the fundamental physics both numerically and analytically, of the combined influence of heterogeneity, viscous forces, gravity, and capillarity on multiphase flow of CO₂ and brine. Specifically, steady-state 3D coreflood displacements in heterogeneous cores over a range of relevant conditions are simulated to study the impact of sub-core heterogeneity on CO₂/brine displacements over a wide range of flowrates. Various degrees of heterogeneity are generated based on the normal random distribution as well as for real models of cores based on 3D X-Ray tomography. A 2D semi-analytical model considering gravity and permeability heterogeneity is developed for predicting brine displacement efficiency over a wide range of capillary numbers that provides good agreement with the simulated 3D results. The analytical derivation is general and the provided solution can estimate the flow regimes for horizontal core floods efficiently.