Yousef Kazemzadeh

This study intends to take a new look at the application of NPs as a nanocomposite form for the first time to gain the most from the effects of them for EOR purposes. For this, TiO2/SiO2 and Fe3O4/SiO2 nanocomposites were first synthesized and investigated for EOR purposes by different experiments, including contact angle, interfacial tension (IFT), injected fluid viscosity, NPs retention in porous medium and carbonate sand pack floodings. The results showed that each NP and nanocomposite presents a distinctive behavior depending on the pressure of the porous medium, with all bringing higher oil production compared to that of seawater (SW) injection. At the ambient pressure, the dominant mechanism during TiO2 and TiO2/SiO2 nanofluid injection was found to be the IFT reduction along with wettability alteration. Whereas, at the intermediate pressure (1500 psi), the wettability alteration by TiO2 NPs and TiO2/SiO2 nanofluids was regarded to be the dominant EOR mechanism and recorded a recovery factor of 60 and 72%, respectively. At the high pressure (3500 psi), the dominant mechanism was observed to be asphaltene adsorption by Fe3O4 NPs and Fe3O4/SiO2 nanocomposites leading to the ultimate recovery factor of 56 and 69%, respectively. The highest incremental recovery for NPs was observed for tertiary injection of SiO2 nanofluid at 1500 psi, which increased the oil recovery by 14%. Whereas, Fe3O4/SiO2 and TiO2/SiO2 nanofluids increased the oil recovery by 24 and 23% at the pressures of 3500 and 1500 psi, respectively. This confirms the efficient role of the synthesized nanocomposites for improved oil recovery. Finally, the results of absorbance measurements of the inlet and outlet of the sand pack during Fe3O4/SiO2 nanofluid injection indicated a 32.4% NPs retention in the porous medium.