Natural polymer non-covalently grafted graphene nanoplatelets for improved oil recovery process: A micromodel evaluation

Abstract

Low stability of the colloidal suspension and the agglomeration phenomena of nanoparticles are the main challenges that restrict nanofluid applications in enhanced oil recovery at reservoir conditions. In this study, graphene nanoplatelets (GNPs) grafted with Gum Arabic (GA) were successfully prepared and evaluated as a cost-effective agent for chemically enhanced oil recovery. The physical and morphological properties of the GA-grafted GNPs (GA-GNPs) were characterized using Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, thermal gravimetric analysis, and transmission electron microscope. GA-GNP powder was prepared and dispersed in high-salinity brine of 30,000 ppm as the base fluid with concentrations of 0.01, 0.05, and 0.1 mg/ml. Investigation results showed that the developed nanofluids exhibited good stability at high salinity and temperature. A reduction in the value of oil–brine interfacial tension (IFT) by 61.0% in the presence of GA-GNPs was observed. The contact angle was remarkably changed from 108° to 20° (81.0% reduction) after dispersing 0.05 mg/mL of GA-GNPs in the brine, which indicates that the wettability of glass slices was altered from oil- to water-wet. After flooding GA-GNP-based brine in the glass micromodel, an augmentation in the oil recovery of approximately 15% and 19% was observed for 0.01 and 0.05 mg/ml of GA-GNPs, respectively. Hence, the wettability alteration plays a more important and effective role than IFT in improving oil recovery with even ultralow concentrations of GA-GNPs. The viscosity of the brine was remarkably improved by 63% after adding 0.05 mg/ml of the prepared GA-GNP powder, which in turn reduced the fingering phenomena during flooding noticeably. These findings indicate that the GA-GNP-based nanofluids can significantly improve the mobility of the residual oil from the porous media to the production well with high efficiency of oil displacement at reservoir conditions.