The impacts of hybrid of microbial enhanced oil recovery and low salinity water flooding on oil recovery mechanisms: An experimental and theoretical Investigation

Microbial enhanced oil recovery (MEOR) and low salinity water flooding have been identified as effective environmentally friendly approaches to enhance oil recovery in different reservoirs. Due to the complexities of behaviors of microorganisms and ions, the impact of low salinity water and MEOR on oil recovery mechanisms is not yet well understood. The present work attempts to study the impact of these approaches on wettability alteration through the measurement of contact angle and zeta potential, as well as theoretical analysis of surface forces. In addition, several lab core flooding scenarios are defined to evaluate the oil recovery and the combination of low salinity water flooding and MEOR increased oil recovery to more than 44 %. In this study, disjoining pressure, which is known as summation of structural forces, electrostatic double layer repulsive forces, and van der Waals attractive forces, is employed to determine the impact of ion types (MgCl2, CaCl2, NaCl, and KCl), concentration (500, 2000, and 4000 ppm) and presence of Acinetobacter lactucae (Ib-30) microorganism on oil recovery mechanisms. The results implied that the disjoining pressure profile is more sensitive to ion types rather than their concentrations. Moreover, removing divalent ions would have a positive effect on the wettability alteration, and there was an interesting consistency between contact angle measurements and disjoining pressure isotherms. © 2024 Elsevier B.V.