Advances In Smart Water Flooding: A Comprehensive Study On The Interplay Of Ions, Salinity In Carbonate Reservoirs: A comprehensive study on the interplay of ions, salinity in carbonate reservoirs

The utilization of smart water flooding to enhance oil recovery (EOR) has gained great interest in carbonate reservoirs. This research analyzed previous studies on how smart water injection affects the wettability and dissolution of various carbonate rocks. A table was presented summarizing the multiple authors' agreement on primary mechanisms. A critical analysis was then performed, focusing explicitly on the agreement and disagreement among authors regarding various factors related to calcium carbonate, limestone, and dolomite rock. For the first time, salinity vs contact angle change plots have been created based on rock's initial condition. The data collected included contact angle, salinity, ion concentration before and after flooding, temperature, and crude oil properties. The modification of wettability is primarily ascribed to the electrical double layer and multi-ion exchange processes, while rock dissolution plays a secondary role in this regard. The use of low salinity smart water led to a change in wettability from being oil-wet to becoming water-wet when initial conditions strong oil wet, oil wet or intermediate wet. The sulfate ion played an important role in dolomite, calcium ion concentration in limestone, and a combination of calcium-sulfate and magnesium-sulfate ions in calcium carbonate rock. The research has established that high salinity triggers the formation of more oil-wet conditions in calcium carbonate rock, and individual ions have been identified as playing a crucial role in enhancing oil recovery. Dissolution of the rock is not a continuous process and is dependent on equilibrium. This process occurs mainly during the early stages of brine injection. The dissolution rate is affected by the injection pressure and contact time, and it is unlikely to contribute significantly to improving oil recovery by altering permeability. The study has shown that increasing temperature can enhance the rock surface's ability to adsorb ions. These findings are crucial for developing and enhancing smart water flooding techniques aimed at increasing oil recovery from carbonate reservoirs.