SmartWater Synergy with Chemical EOR: Studying the Potential Synergy with Surfactants

Abstract

Abstract The potential synergy between SmartWater and various EOR processes has recently attracted significant attention. In previous work, we demonstrated such favorable synergy for polymer floods not only from a viscosity standpoint but also in terms of wettability. Recent studies suggest that such synergy might extend to even surfactant floods. In this work, we investigate the potential synergy between SmartWater and surfactant flooding. Opposed to previous work, the potential synergy is investigated from ground zero. We concurrently developed two surfactant formulations for conventional high salinity injection water and low salinity SmartWater. The formulations were designed for an actual carbonate case exhibiting harsh reservoir conditions. To design the two surfactant-polymer (SP) formulations, we followed a systematic all-inclusive laboratory workflow. Oil displacement studies were performed in preserved core samples using the two developed formulations with conventional injection water and SmartWater. The results demonstrated the potential of binary surfactant mixtures of Olefin Sulfonate (OS) and Alkyl Glyceryl Ether Sulfonate (AGES) for both waters. The designed binary formulations were able to form to Winsor type III emulsions besides achieving ultralow interfacial tensions. Most importantly, in terms of oil displacement, the developed SP formulations in both injection water and low salinity SmartWater were capable of recovering more than 60% of the remaining oil in core post waterflooding (ROIC). A key novelty of this work is that it investigates the potential synergy between SmartWater and surfactant-based processes from the initial step of surfactant formulation design. Through such from-scratch evaluation, we demonstrate that surfactant-based processes exhibit limited synergies with SmartWater. Comparable processes in terms of performance can be designed with both high-salinity and low-salinity waters. It is also quite possible that the synergistic benefits of SmartWater on oil recovery cannot be effective in SP flooding processes especially under optimal salinity conditions.