Impact of Mutual Solvents on Wettability Alteration for EOR Application by Hybrid Smart Water and Green SiO₂/KCl/Xanthan Nanocomposites in Carbonate Reservoirs

Chemical methods have recently been applied in most large projects to enhance oil recovery. However, conventional chemical EOR solutions face problems in displacing and mobilizing crude oil in porous media. To enhance oil recovery and reduce costs, new techniques can be developed that include nanotechnology and combined methods. In this study, ethanol and methyl ethyl ketone were used to evaluate the wettability alteration (quantitative and qualitative wetness) of carbonate reservoir rocks under the influence of synthesized nanocomposites (NCs), called SiO2/KCl/xanthan, at different salinity levels of formation water. The obtained results show that the contact angle decreases with decreasing salinity of the base fluid. However, the contact angle decreases with increasing salinity when the solvent is introduced. As the volume percentage of solvents in the base fluid increases, the contact angle decreases. Meanwhile, the synthesized NCs were able to reduce the contact angle, but the smart water/mutual solvent/NC hybrid solution in the optimal concentration has a better effect on rock wettability alteration from hydrophobic to hydrophilic (a significant change in the contact angle from 125.1 to 39.2 degrees). Finally, a mixture of 50% formation water and 50% distilled water with 15% methyl ethyl ketone showed the highest impact on the wettability alteration in the presence and absence of nanocomposites. Moreover, the original oil in place (OOIP) within the rock core plugs dropped by 53 and 59.15% for the mentioned mixture results with and without the presence of the nanocomposites, respectively.