Synergistic interaction of nanoparticles with low salinity water and surfactant during alternating injection into sandstone reservoirs to improve oil recovery and reduce formation damage

Several studies have revealed that nanoparticles (NPs) can improve oil recovery when injected into the reservoir by modifying the important properties of the rock and fluid such as wettability, interfacial tension (IFT), and viscosity. A little understanding of the mechanisms involved during the interaction of NPs with the reservoir rock and fluid has been a great concern to apply NPs for enhanced oil recovery (EOR). Therefore, this study presents a comprehensive analysis of the mechanisms involved when NPs are alternatingly injected with low salinity water (LSW) and surfactant into sandstone reservoirs for EOR. A series of coreflooding experiments is performed on different core plugs taken from the outcrops of Bentheimer sandstone to determine the oil recovery during different alternating injections of silica NPs, surfactant, and LSW at temperature and pressure of 70 degrees C and 3000 psi, respectively. In addition, the changes in wettability and IFT with different alternating injections of silica NPs, surfactant, and LSW into the core plugs are measured. The results revealed that the sequential injection of aqueous solution (LSW or surfactant) after injecting NPs restores the permeability of the core plug, which is damaged by the deposition of NPs on the wall of the pores and pore throat. It was also observed that the viscosity of a mixture of NPs and LSW or surfactant is higher than other solutions, which contributed to the oil recovery. This work has shown that the cyclic variation in wettability, IFT reduction, and viscosity change during the alternating injection of NPs, LSW, and surfactant into the reservoir are the best mechanisms to optimize oil recovery and prevent formation damage. Therefore, this study presents a novel method for an economical, efficient, and effective implementation of NPs. (c) 2020 Elsevier B.V. All rights reserved.