Crude Oil Interfacial Tension Reduction and Reservoir Wettability Alteration with Graphite or Activated Carbon/Silica Nanohybrid Pickering Emulsions

In this research, two carbon structures silica nanohybrids Pickering emulsions were prepared. Graphite and activated carbon were carbon allotropes with different morphologies of laminar and spherical, respectively. The effect of carbon morphology investigated on the related silica nanohybrids Pickering emulsions for C-EOR. Therefore, nanohybrids were prepared with graphite and activated carbon through the sol-gel method based on different weight percents and two different methods. X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and Thermal Gravimetric Analysis (TGA) used characterize the synthesized samples. Pickering emulsions of these nanohybrids were prepared by utilizing octane as oil model, suitable anionic surfactants and an alcoholic co-surfactant with pH=7 at room temperature using distilled water. The apparent stability of Pickering emulsion studied over a period of one month. The results of analyses indicated that graphite/silica nanohybrids Pickering emulsions had superior properties for C-EOR in comparison to activated carbon/silica nanohybrids Pickering emulsions. It concluded that laminar morphology is more significant than the spherical morphology of carbon structure for the mentioned purpose. According to emulsion phase morphology, the optical microscopic images showed that the best samples were 70% graphite/silica (method 2) and 50% activated carbon/silica (method 2). The results of contact angle measurement represented that the 70% graphite/silica nanohybrid (method 2) is more effective on the stone reservoir improvement, which can change the wettability from oil-wet to water-wet. Nanofluid of 70% graphite/silica nanohybrid (method 2) could reduce interfacial tension.