Application of Mineral Nanofluids in Enhanced Oil Recovery (EOR) of Carbonate Oil Reservoirs: A Laboratory Study

One of the most important methods of increasing extraction from carbonate reservoirs is to change the wettability of the reservoir rock with the emergence of nanotechnology, which played a significant role in the framework of methods of increasing Oil Recovery. The purpose of this project is to use nanofluids containing inorganic nanoparticles, which are economical and environmentally friendly. For this purpose, first, 3 types of inorganic nanoparticles SiO₂, Al₂O₃ and TiO₂, which were converted into nanometer size powder by mechanical method (Ball mill). Then, 3 nanofluids containing SiO₂, Al₂O₃ and TiO₂ were prepared along with dispersants and stabilizers. By performing the contact angle test, it was found that the contact angle of the oil drop on the oil-wet carbonate rock changed from 132.1° to 87.1° after coating with nanofluid with a concentration of at least 0.01 wt.%. Then the optimal concentration of nano fluid and the optimal time of thin section aging in nano fluid were determined, and the values of these parameters were 0.01% by weight and 7 days, respectively. In the following, it was shown that the stone coated with these nanofluids maintains its wettability well. Based on the interfacial tension test, it was shown that the interfacial tension decreased from 24.029 mN/m (water and oil) to 4 mN/m (nanofluid and oil) at ambient temperature. Finally, by conducting the Core Flooding test on the oil wet plugs, the investigations show that in the flooding test, the volume of extracted oil increased by 42.06% in the case of water injection to 60.09% in the case of nanofluid injection. (Residual oil decreased from 9.64 cm³ to 6.64 cm³ respectively.) In fact, the flooding recovery factor increased by 18% compared to the previous state.