Evaluation of stability and functionality of zinc oxide nanofluids for enhanced oil recovery

Nanofluids for enhanced oil recovery offer a breakthrough solution towards tertiary recovery and consequently higher oil production. Their ability to reduce interfacial tension, alteration of formation’s wettability, higher adsorption capacity, and acceleration of disjoining pressure makes them excellent candidates for enhanced oil recovery. The main objective of this paper is to investigate the effect of polymers on zinc oxide (ZnO) nanofluids for enhanced oil recovery (EOR) and the role played by chemical modification using polymer stabilizers on nanoparticle stability in nanofluids. Nanoparticles with an average particle size of 34 nm were synthesized and used to prepare nanofluids of different concentrations and their stability was evaluated using sedimentation and UV–vis spectrophotometry tests. ZnO-synthesized nanofluids were used solely and in addition to Polyvinylpyrrolidone (PVP) and Polyvinyl alcohol (PVA) as stabilizing agents. It was noted that ZnO nanofluids with PVA stabilizer recorded the highest oil recovery of 82%. In contrast, the ZnO nanofluids without stabilizing agents registered the lowest recovery rate during the flooding experiment. The results revealed that a higher injection rate increases the oil recovery and reduces the viscous fingering effect with a better displacement front. Furthermore, nanofluids containing polymeric stabilizing agents achieved better recovery factors compared to ZnO nanofluids without stabilizing agents. This phenomenon was also observed in the interfacial tension test where nanofluids with PVA and PVP stabilizers reduced the IFT by 59% and 61% respectively.