Experimental investigation of wettability alteration and oil recovery enhance in carbonate reservoirs using iron oxide nanoparticles coated with EDTA or SLS

Recently, nanoparticles (NPs) coated with chemical agents like polymers and surfactants have attracted much attention for the wettability alteration of reservoirs from oil-wetting to water-wetting in order to increase oil production rate. In this research, Fe3O4 NPs were synthesized using the co-precipitation method and coated with Ethylenediaminetetraacetic (EDTA) as a hydrophilic polymer or Sodium Lauryl Sulfate (SLS) as an ionic surfactant by the dip-coating method to alter the wettability from oil-wetting to water-wetting in carbonate rocks. The coated NPs were characterized by the Field Emission Scanning Electron Microscope (FE-SEM), X-ray diffraction device (XRD), Fourier-transform infrared spectroscopy (FTIR), Zeta-potential measurements, and the Vibrating-sample magnetometer (VSM) analysis. In addition, the effect of different parameters on wettability alteration including the variation of nanofluids concentration, pH level, salinity, temperature, pressure, and exposure time via contact angle experiments was investigated. Finally, the imbibition experiments were fulfilled to observe the performance of nanofluids in enhancing oil recovery at core-scale. Our results showed that the coated Fe3O4 NPs have excellent water-wetness properties in low salinities (i.e. less than 5000 ppm). Additionally, the Scanning Electron Microscope (SEM) micrographs, Zeta-potential measurement and FTIR analysis taken from the carbonate plates confirmed the adsorption of NPs on the carbonate-rock surface. Moreover, the Fe3O4 NPs coated with SLS in comparison with those coated with EDTA have higher performance in reduction of contact angle, and hence enhancing more oil recovery (EOR).