What is the Optimum Wettability for Oil Recovery Through Waterflooding?

This work provides a review of Improved/Enhanced oil recovery research to answer the critical question about the optimum wettability for oil recovery through conventional and low salinity waterflooding (LSW). As the answer is not straightforward, this work investigates conflicting views in a manner that justifies conclusions and provides comparisons between different rock types and conditions. Analysis relating all parameters affecting oil recovery is linked to wettability to identify the optimum state for different waterflooding schemes. Relying solely on core-based analysis, or any other method, is argued to be not conclusive without considering the conditions of core handling and testing, pore-network structure, contact angle tests, and field-scale considerations. Therefore, comprehensive conclusions should come from cross-factor analysis rather than isolating certain factors, when studying optimum wettability for oil recovery. This work provides a reference for researchers to approach this dichotomy through an overview of previous works in this area.