Optimizing wettability alteration in carbonate reservoirs using hybrid low saline brine formulations for enhanced oil recovery

Abstract

The study explores the effects of hybrid low-saline brine (LSB) formulations on wettability alteration to promote oil displacement efficiency in carbonate reservoirs. It  addresses the challenges of shifting rock surfaces from oil-wet to water-wet conditions, particularly in high-salinity, and temperature environments. Five hybrid LSB injection schemes were designed, incorporating different salts, xanthan polymer, silica nanoparticles, and reef salts to improve wettability alteration in carbonate cores. The Fourier Transform Infrared spectroscopy (FTIR), revealing significant changes in mineralogy, and surface structure. Contact angle (CA) measurements were performed to evaluate the impacts of modified LSB on carbonate cores, signifying that rock-brine-oil interactions potentially altered the surface chemistry, shifting wettability from oil-wet to water-wet. The findings reveal that higher salinity and temperature improved the wettability shift, decreasing CA from 126° to 80°. Scheme 5, containing silica nanoparticles, reef salts, and xanthan polymer, significantly altered surface alkalinity and wettability by reducing CA over 30° at 60°C. This indicates that higher salinity and temperature in LS brine enhance wettability alteration and decrease interfacial tension, substantial for efficient oil recovery. The study confirms the usefulness of hybrid LSB formulation in wettability alteration, advancing enhanced oil recovery (EOR) techniques in carbonate reservoirs, under complex conditions