An Extensive Evaluation of Different Reservoir Simulators used for Polymer Flooding Modeling

The global interest in enhanced oil recovery (EOR) methods has been increasing recently as a source of satisfying the ever increasing energy demand. This is due to maturing of most of the existing and significant hydrocarbon reservoirs as well as the very limited number of new oil major reservoir discoveries. This is added to the challenging existing reservoirs conditions such as viscous oil, mixed-to-oil wettability, heterogeneity, and high temperature high salinity (HTHS). Polymer flooding is one of the robust and inexpensive EOR processes that improves sweep as well as displacement efficiencies. However, modeling of polymer flooding is a challenging task due to the difficulty in portraying all of the key physico-chemical aspects such as polymer rheology, adsorption equilibrium, inaccessible pore volume, and behavior against high salinity and hardness. This challenge has shifted the attention and efforts towards developing reliable reservoir simulators as tools for predicting and mitigating the risks-involved with polymer flooding projects. In this study, we present a critical review of recent modules from different numerical simulators with chemical EOR (cEOR) competences such as CMG-STARS, ECLIPSE-100, and UTCHEM to model polymer properties. The review starts with description of numerical formulation and applications for different simulators. This is followed by descriptions of polymer models including viscosity, salinity effect, rheology, adsorption, and permeability reduction. Afterwards, the assessment of different simulators is presented through polymer flooding simulation cases as reported in the literature. It is to be noted that the overall results did not provide an insight into algorithm efficiency or computational cost of different numerical simulators, but instead mainly focused on the mechanistic modeling of the process with different parameters. The results suggest that with an appropriate mechanistic modeling of polymer flooding, there is potential for accurate prediction and optimization of various polymer flooding projects under diverse conditions, which is expected to positively impact the oil recovery efficiency and related economics. This study provides insights about the application scopes of different numerical simulators and their competences under diverse reservoir scenarios in order to obtain optimized performance of a polymer flooding field project.