Enhanced oil recovery by wettability alteration using iron oxide nanoparticles covered with PVP or SDS

Wetting phenomena have been extensively investigated in treatment of rocks surface in oil reservoirs using nanofluids for enhanced oil recovery (EOR) purposes. Nanoparticles (NPs) have shown their potential in EOR through surface modification, which results in wettability alteration. In our previous study, the synthesized Fe3O4 NPs coated with Ethylenediaminetetraacetic (EDTA) or Sodium Lauryl Sulfate (SLS) showed good results for wettability alteration phenomenon resulting in EOR. In the present study, the same synthesized iron oxide NPs have been covered with new agents of Polyvinylpyrrilidone (PVP) as a hydrophilic polymer or Sodium Dodecyl Sulfate (SDS) as an ionic surfactant using the same experimental technique as before. Full characterization of the modified NPs has been carried out using Field Emission Scanning Electron Microscope (FE-SEM), X-ray Diffraction device (XRD), Transmission Electron Microscopy (TEM), Fourier-Transform Infrared spectroscopy (FTIR), and the Vibrating-Sample Magnetometer (VSM) analysis. The Scanning Electron Microscope (SEM) micrographs and FTIR analysis and Zeta-potential measurements on the treated carbonate-rock surface decorated with the NPs showed strong wettability alteration from oil-wet to water wet. The effect of various parameters including the concentration of the mentioned NPs in water-based nanofluid, exposure time, pH, salinity, temperature and pressure on wettability alteration of oil-wet carbonate-rock surface was comprehensively investigated by contact angle measurements. Additionally, the imbibition tests were conducted to determine the potential of the nanofluids in EOR at core-scale. Moreover, the stability of nanofluids in the absence and presence of salts was assessed with Zeta-potential measurements. Our final results showed that NPs covered with PVP and or SDS resulted in 16 % and 13 % increase in oil recovery compared to brine alone, respectively.