Synthesis and application of the novel metal nitrate/graphene oxide nanocomposites in enhancing oil recovery at ultra-high salinities

Abstract

Herein, it was aimed to enhance the oil recovery by exploiting the mechanisms involved in leveraging the rock and fluid characteristics. To this end, various nanostructures, including nanocomposites of Poly Citric Acid (PCA) grafted graphene oxide (G.O) and Al, Cu, and Mg nitrates, were synthesized. The prepared nanocomposites were investigated at high salinities (8 wt% CaCl2 and 8 wt% NaCl) for enhanced oil recovery (EOR). Rock wettability and interfacial tension (IFT) enhancement were investigated to show improvement in the oil recovery. Furthermore, core flood experiments were performed using a crude oil sample and a water solution at high salinities (8 wt% CaCl2 and 8 wt% NaCl). The results revealed that synthesized nanofluids were stable at high water salinities and could displace the trapped oil in sandstone core samples, implying nanofluids' positive role in oil recovery improvement. Also, contact angle values were measured at different concentrations by the time. The results indicated the wettability alteration as an effectual mechanism in the EOR through applied disjoining pressure by these particles. As the second mechanism for fluid-fluid interactions, interfacial tension reduction was investigated at three concentrations. It was also found that at 500 ppm concentration, the best tertiary recovery enhancement of 13.55% was obtained for Mg/GO-g-PCA followed by Cu/GO-g-PCA (11.3%) and Al/GO-g-PCA (9.72%), which is a remarkable result. So, these novel synthesized materials can be applied at such high salinities (8 wt% CaCl2 and 8 wt% NaCl). As high water salinity is one of the main challenges in using chemicals for enhancing oil recovery, the results of this study can be beneficial to overcome this issue.