In this research, we have proposed a very simple and economical preparation method for nanoporous graphene/silica nanohybrid (sol-gel method) that the related Pickering emulsion will be suitable for Chemical Enhanced Oil Recovery (C-EOR). This preparation method is preferred to the similar previous researches. For evaluation of the mentioned Pickering emulsion properties, we have prepared other carbon structures (MWCNT and graphite)/SiO2 nanohybrids with different weight percent. The as-prepared nanomaterials were characterized with X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Thermal Gravimetric Analysis (TGA). The nanohybrids Pickering emulsions were prepared with n-Octane as oil model, suitable anionic surfactant (such as SDBS) and 2-Propanol as alcoholic co-surfactant at pH = 7 in ambient temperature and with distilled water. The mentioned Pickering emulsions stability was controlled for one month. Emulsion phase morphology was investigated with optical microscopic image. Evaluation results demonstrated that the best samples are MWCNT/SiO2 and nanoporous graphene/SiO2 nanohybrids. Stability of the selected nanohybrids was investigated by alteration of salinity, pH and temperature and results showed that the related Pickering emulsions of the selected nanohybrids have very good stability at 1% salinity, ambient and several oil reservoir temperatures (25 degrees C, 90 degrees C, 105 degrees C and 120 degrees C) and neutral and alkaline (7,10) pH that is suitable for the oil reservoirs conditions but contact angle measurement results showed that the nanoporous graphene/SiO2 nanohybrid is more effective for improvement of the stone reservoir wettability alteration from oil-wet to water-wet in comparison to the other samples. Interfacial tension evaluations indicate that the maximum amount is related to the injection of water and the minimum amount is related to the injection of nanoporous graphene/SiO2 nanohybrid nanofluid. This result indicates the nano porous graphene/SiO2 nanohybrid can better reduce the interfacial tension in comparison to the other samples. Our results demonstrated that the nanoporous graphene/SiO2 nanohybrids Pickering emulsion has superior properties to the MWCNT/SiO2 nanohybrids Pickering emulsion (that we presented in our previous research) for Chemical Enhanced Oil Recovery (C-EOR) and the nanoporous graphene/SiO2 nanohybrid can improve the rheological behaviour of polymer suspensions that are suitable for polymer flooding technique. (C) 2017 Elsevier Ltd. All rights reserved.