Secondary and tertiary mode of recovery in low salinity waterflooding: a comprehensive study with insights into wettability alteration and interfacial tension

This study offers a thorough examination of Enhanced Oil Recovery (EOR) tactics using core flooding and imbibition cell experiments. It aims to evaluate how using low-salinity water (LSW) influences crude oil displacement in low-permeable sandstone formations. The primary objective was to discern and quantify the differences between the secondary and tertiary recovery modes while investigating wettability alteration with low- and high-salinity waters (LSW and HSW) and interfacial tension (IFT) reduction. A specialized core flooding setup was employed to simulate reservoir conditions in low permeable sandstone rock, a crucial yet challenging reservoir type. The experimental design incorporated both secondary and tertiary flooding modes, allowing for a systematic comparison of their efficacy in enhancing oil recovery. Imbibition cell studies provided additional insights into the dynamic relationships among the rock matrix, varying salinity water, and crude oil. The study delved into wettability alteration to grasp the subtle impacts on the rock’s surface of both LSW and HSW. The findings underscore the significance of water salinity in altering rock wettability and its consequent influence on the effectiveness of oil extraction. Remarkably, the analysis reveals that the secondary mode yields greater extra oil recovery in sandstone rock with low permeability, as compared to the tertiary mode. IFT measurements were conducted to complement the findings, offering a detailed understanding of the fluid–fluid interactions within the porous media. The differences in IFT between LSW and HSW systems contribute significantly to fully understanding the complex connections between fluid properties and rock wettability. The outcomes of this study have significant implications for EOR strategies in low permeable sandstone reservoirs, as the preference for secondary mode flooding over tertiary mode is demonstrated. The insights gained regarding wettability alteration and IFT provide valuable guidance for optimizing EOR techniques tailored to the specific challenges posed by low-permeable sandstone rock formations.