Advancements in Surfactant-Polymer Flooding Modeling: An Extensive Review of Reservoir Simulation Tools
Authors: Zeynalli Mursal , Hassan Anas M. , Fathy Ahmed , Al-Shalabi Emad W. , Iskandarov Javad , Arellano Aaron G. Tellez , Kamal Muhammad S. , Patil Shirish 
Published: April 2024

Abstract
Despite advances in renewable energy, fossil fuels remain the primary energy source, necessitating the enhancement of oil recovery techniques for both existing and new oil fields. Surfactant-polymer flooding stands out as a promising method for improving oil recovery, with its potential to alter the intricate dynamics of fluid-rock interactions in porous media. It offers distinct advantages, as polymers enhance the mobility and conformance of the injectant, mitigating issues such as viscous fingering and channeling, whereas surfactants mobilize residual oil by reducing interfacial tension and creating favorable wettability conditions. However, accurate modeling of surfactant-polymer flooding is paramount for optimizing this enhanced oil recovery (EOR) technique by understanding complex interactions, addressing inherent limitations, and facilitating informed decision-making in reservoir engineering. This paper provides a comprehensive investigation of recent advancements in surfactant-polymer modeling within prominent reservoir simulation tools, including UTCHEM, CMG-STARS, ECLIPSE, and MRST simulators. The polymer models implemented in various simulators demonstrate a wide range of functionalities, accurately portraying polymer viscosities under varying salinities and polymer concentrations, capturing non-Newtonian behavior, and accounting for phenomena such as adsorption and permeability reduction. Particularly, both UTCHEM and MRST simulators exhibit remarkable capabilities in handling polymer viscoelasticity and its impact on oil recovery. Moreover, the manually embedded correlations in MRST appear to be well-suited and effective for representing polymer mechanical degradation.
On the other hand, an examination of surfactant modules in the studied simulators demonstrated the exceptional capabilities of UTCHEM, especially in the characterization of microemulsion viscosity and proper analysis of surfactant phase behavior. Unlike other simulators, UTCHEM adeptly identifies all three microemulsion types, encompassing Winsor Type I, II, and Type III. Additionally, for interfacial tension reduction, UTCHEM employs a variety of correlations, setting it apart from other simulators that primarily rely on tabular input for defined interfacial tension values, thereby underscoring another advantage of UTCHEM in modeling surfactant flooding. Finally, the incorporation of geochemical reactions significantly improves the modeling of interactions between the injected materials and the reservoir’s rock and fluids. UTCHEM encompasses extensive geochemical reaction models, covering reactions involving aqueous species, dissolution/precipitation of solid species, exchange species reactions, and surfactant-related exchange species reactions. However, CMG-STARS provides the option to either import geochemical reactions from the CMG library or allow users to insert them, ensuring minimal mass balance errors and using experimentally determined equilibrium constant values. Meanwhile, ECLIPSE triggers geochemical reactions using a specific set of keywords, while the integration of MRST with the PHREEQC system enables the utilization of geochemical reactions to assess the concentration of individual chemical species and mineral properties. The latter involves considerations such as aqueous speciation, mineral dissolution/precipitation, ion-exchange activities, and surface complexation reactions. This research serves as a benchmark for the industry, providing insights into the strengths and limitations of different simulation tools. The findings offer a detailed perspective on the dynamic developments in surfactant-polymer modeling, paving the way for enhanced decision-making in reservoir engineering and contributing to the advancement of enhanced oil recovery practices.