Numerical Simulation Guideline of Oil Recovery by Cycle-Dependent Three-Phase Process Using Coreflood Experiments

Many oil reservoirs worldwide have cycle dependent oil recovery either by design (e.g. WAG injection)or unintended (e.g. repeated expansion/shrinkage of gas cap). However, to reliably predict oil recoveryinvolving three-phase flow process, a transformational shift in the procedure to model such complexrecovery method is needed. Therefore, this study focused on identifying the shortcomings of the currentreservoir simulators to improve the simulation formulation of the cycle-dependent three-phase relative-permeability hysteresis. To achieve this objective, several core-scale water-Alternating-gas (WAG) injection experiments wereanalysed to identify the trends and behaviours of oil recovery by the different WAG cycles. Furthermore,these experiments were simulated to identify the limitations of the current commercial simulators availablein the industry. Based on the simulation efforts to match the observed experimental results, a newmethodology to improve the modelling process of WAG injection using the current simulation capabilitieswas suggested. Then the WAG injection core-flood experiments utilized in this study were simulated tovalidate the new approach. The results of unsteady-state WAG injection experiments performed at different conditions were used inthis simulation study. The simulation of the WAG injection experiments confirmed the positive impact ofupdating the three-phase relative-permeability hysteresis parameters in the later WAG injection cycles. Thischange significantly improved the match between simulation and WAG experimental results. Therefore, asystematic workflow for acquiring and analyzing the relevant data to generate the input parameters requiredfor WAG injection simulation is presented. In addition, a logical procedure is suggested to update thesimulation model after the third injection cycle as a workaround to overcome the limitation in the currentcommercial simulators. This guideline can be incorporated in the numerical simulators to improve the accuracy of oil recoveryprediction by any cycle-dependent three-phase process using the current simulation capabilities.