Modeling imbibition coreflooding in heterogeneous cores with sub-core scale hysteresis

Coreflooding experiments with computed tomography imaging are becoming common practice. They allow to investigate the sub-core scale properties such as relative permeability (k_r) and capillary pressure (P_c), and to construct multiphase flow models that not only capture the core average flow, but also the flow on the sub-core (millimeter) scale. This work presents two-phase flow models of imbibition coreflooding in two heterogeneous core samples which underwent drainage and imbibition experiments, as part of a previous investigation. The models incorporate hysteresis in two approaches: global and sub-core. The latter includes unique P_c and k_r for each grid block of the core depending on the turning point and residual saturations measured in the experiments. The simulation output of grid-block (sub-core) saturation distribution is compared to the experimental data. Results show that the sub-core hysteresis model matches the experiments more accurately than the global model. This is particularly important for the core with a higher degree of heterogeneity in which the global hysteresis model shows large errors while the model incorporating sub-core hysteresis is significantly more accurate.