Attention to nanotechnology for EOR purposes has been Attention to nanoparticles for EOR purposes has been proliferated in the last decades due to their unique properties. On the other hand, smart water is an efficient EOR method that has been noticed by reservoir engineers. This research attempts to benefit from the synergistic effects of both methods (nanoparticles + smart water) for improved oil production. For this purpose, the smart water was first synthesized in the laboratory by NaCl and MgSO 4 salts, according to the compositional analysis of a seawater sample and the effect of different acids (HCl and C 2 H 4 O 2 ) and bases (NH 3 and NaOH) on the stability of Al 2 O 3 nanofluids were monitored by the imaging technique. The asphaltenic oil/water IFT measurements were designed in two cases: (1) constant NaCl concentration and constant MgSO 4 concentration, both at different concentrations of Al 2 O 3 nanoparticles and different temperatures. The contact angle measurements of oil/nano-smart water/quartz system were carried out for different concentrations of Al 2 O 3 nanoparticles, NaCl, and MgSO 4 at different temperatures. The effect of nanoparticles on the oil/water interfacial viscosity, asphaltene adsorption, and the viscosity of oil bulk and water/oil emulsion was also investigated. In the end, the optimum cases obtained from IFT and contact angle measurements were analyzed by absorbance spectrum for further stability investigation and then were injected into an oil-wet porous medium in a glass micromodel. The stability investigation indicated that HCl provided the highest stability time at pH 2.6, which mainly results from the development of surface charges and repulsive forces between particles in suspension. The results on IFT measurements showed the minimum IFT in two cases: (1) a 50% reduction in IFT value (from 38.1 to 18.9 mN.m -1 ) with the addition of 4 times MgSO 4 seawater concentration (at NaCl seawater concentration) and 0.2 gr/L Al 2 O 3 nanoparticles and (2) a 60% reduction in IFT value (from 38.1 to 15.9 mN.m -1 ) by the reduction of NaCl seawater concentration by 3 times (at MgSO 4 seawater concentration) and 0.1 gr/L Al 2 O 3 nanoparticles, both at pH 2.6 and 60?. The results show that the reduction of inactive ions (Na + and Cl - ) of the base fluid is of greater importance, compared to the increase in potential determining ions (Mg 2+ and SO 4 2- ) since it provides lower IFT values with lower nanoparticle concentrations. The contact angle results show that increasing MgSO 4 seawater concentration by 4 times (at NaCl seawater concentration) has changed the quartz wettability from strongly oil-wet (155°) to the strongly water-wet (42°) over 24 hours. Compared to the IFT results, contact angle measurements show that the increase in potential determining ions of base fluid is of greater importance for wettability alteration. The viscosity measurements showed that the catalytic Al 2 O 3 nanoparticles are able to reduce oil bulk and oil/water interfacial viscosity. With this, a new mechanism was proposed for IFT reduction by nanoparticles. The asphaltene adsorption analysis on the 70/30 vol% (oil/water) samples indicated a good fitting to Langmuir Isotherm type (I) with a monolayer adsorption. In the end, the results on the injection of the optimum cases to the porous medium showed an improved oil production by the addition of Al 2 O 3 nanoparticles. The highest recovery factor was observed for the second optimum case obtained from IFT results which resulted in the production of 40% of the original oil in place as a secondary injection and 10% additional recovery factor in the process of DW/smart water/nano-smart water as a tertiary injection