Razieh Khosravi

One of the key challenges in developing heavy oil fields using water-based injection methods is the early breakthrough of injected water and the lack of adequate oil production. This phenomenon can result from unfavorable mobility conditions, which are further exacerbated by reservoir heterogeneity. Under such circumstances, employing polymer injection-based methods can offer significant potential to enhance water-based injection techniques. In this study, an analytical model has been developed for the rapid prediction of polymer flow behavior in both core-scale (micro) and reservoir-scale conditions within a heavy oil reservoir. To achieve this objective, first, an analytical model based on Buckley–Leverett theory was developed at the core scale to design polymer flooding and to investigate the mechanisms influencing enhanced oil recovery. Subsequently, at the reservoir scale, the effects of heterogeneity, expressed in terms of the Dykstra–Parsons coefficient, and salinity (seawater and its diluted conditions) on the performance of the polymer injection method were considered. According to the results, at the core scale, polymer injection led to a 7% increase in oil recovery compared to seawater injection. Under heterogeneous reservoir conditions, this positive performance was more pronounced, resulting in 12% additional oil production compared to seawater injection. Regarding the effect of salinity, the results indicated a synergistic effect of the low-salinity water–polymer injection method, yielding 10% and 4% higher oil production than polymer injection alone at the core and reservoir scales, respectively. The developed analytical model provides a suitable tool for designing the polymer injection process under various salinity and heterogeneity conditions, which can be used to facilitate technical and economic decision-making at the reservoir scale.