Utilization of Janus-silica/surfactant nanofluid without ultra-low interfacial tension for improving oil recovery

Janus nanoparticles with amphiphilic surfaces could be of particular significance for enhanced oil recovery (EOR) of reservoirs. However, currently available methods for preparing Janus nanoparticles are often complicated. Here we present a highly efficient and easily scalable one-step chemical etching method with NaOH as the etching agent for fabricating amphiphilic Janus-SiO2 nanoparticles. The structure, interfacial behavior and improved oil recovery (IOR) potential of the as-prepared Janus-SiO2 nanoparticles were systematically studied. Results show that Janus-SiO2 nanoparticles with size less than 10 nm exhibit good dispersibility in water and amphiphilicity as well. When combined with various surfactants, they can significantly improve the oil recovery upon simulated water flooding, due to their good abilities to increase the sweep efficiency of surfactants and reduce the interfacial tension of oil-water emulsion. Oil recoveries are improved by 7.4-9.8% with addition of Janus-SiO2 in surfactants compared to pure surfactant solutions, showing promising potential for EOR. (C) 2020 Elsevier Ltd. All rights reserved.