Ion type adjustment with emphasize on the presence of NaCl existence; measuring interfacial tension, wettability and spreading of crude oil in the carbonate reservoir

Finding the high-performance anions and cations in the aqueous solutions are crucially required during the smart water injection make it the main core of many enhanced oil recovery (EOR) studies. Nevertheless the previously published literature revealed a lack of understanding about the synergistic or antagonistic effect of NaCl (as the most abundant salt in the sea water) and other salts with the same ionic strength on the interfacial tension (IFT), wettability alteration and spreading coefficient. Therefore, the main purpose of this study is aimed on this concern. To reach this goal, the dynamic IFT values of crude oil/different aqueous solutions with ionic strength of 0.7M and contact angle values between these phases on the oil wet carbonate surface soaked under different times in the prepared aqueous solutions are measured. After that, the measured values are used to calculate the spreading coefficient and distribution capability of oil and water phases on the carbonate rock surface. The obtained results revealed that to change the wetting state of carbonate rock toward a more water wet state, a synergistic effect was observed between NaCl and salts containing sulfate anion, i.e. Na2SO4. and MgSO4.