Potential application of low-salinity polymeric-nanofluid in carbonate oil reservoirs: IFT reduction, wettability alteration, rheology and emulsification characteristics

Polymer and low-salinity water flooding have been shown, repeatedly, to be effective methods for chemical Enhanced Oil Recovery (cEOR). The benefits are obtained by increasing the viscosity of the injected fluid, minimizing the interfacial tension (IFT) of the crude oil/aqueous phase, and by wettability alteration. Similarly, nanofluids (fluids injected with nanoparticles) have also been demonstrated to induce the same processes. We have analyzed the EOR response of green nanofluids when formulated with a typical natural polymer mixed with low salinity water. For this purpose, a polymer coated ZnO/SiO2 nanocomposite (NC) has been produced from the pomegranate seed extract using a simple, economical and, importantly, green method. The characterization of the synthesized NC has been investigated using the scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The polymeric nanofluids were then tested in various experimental studies related to the stability of injected fluids, IFT behavior, wettability alteration, oil/nanofluid emulsification, and EOR flooding dependent on the NC concentration, time and salinity. The low salinity-polymeric nanofluid (LPN), with 2000 ppm NC concentration, enabled higher oil recovery by about 1928% OOIP due to a significant reduction in IFT, higher viscosity, better emulsion stability, and wettability alteration towards a stronger water-wet system from 137 degrees to 34 degrees contact angle. (C) 2019 Elsevier B.V. All rights reserved.