Nanofluids of silica nanoparticles in low salinity water with surfactant and polymer (SMART LowSal) for enhanced oil recovery

Spontaneous imbibition is a common phenomenon noticed in low permeability reservoirs during oil recovery. A considerably good amount of oil can be recovered by imbibition of efficient injection fluid for a prolonged time. Recent interest on the low salinity water injection (LSWI/LowSal) has prompted the development of SMART LowSal injection fluid for enhanced oil recovery (EOR). In this work, novel hybrid silica-based nanofluids (NFs) of varying concentrations of silica nanoparticles (SiO2 NPs) in diluted seawater with anionic surfactant (AOT) and polymer (PVP-K30) (referred to as SMART LowSal) were used as an imbibition agent. Interfacial tension (IFT) and contact angle measurements were carried to understand the impact of novel hybrid NFs on the IFT of oil-NFs system and wettability of rock. Berea sandstone cores were used to understand the efficacy of novel SMART LowSal injection fluid for EOR through spontaneous imbibition. The aged oil saturated cores were analyzed with X-ray computed tomography (CT) and energy dispersive X-ray (EDAX). Amott cell was used for imbibition test to evaluate the efficiency of the novel hybrid NFs for EOR. The oil recovery due novel hybrid NFs is found to be significantly higher than that of LSW and deionized water. The oil saturated core surfaces were analyzed with scanning electron microscopy (SEM) and EDAX before and after oil recovery to understand the surface properties of the cores. The novel hybrid NFs showed excellent potential for enhanced oil recovery (EOR). This is one of the first study of its kind using surfactant, polymer and nanoparticles in diluted seawater to prepare NFs and its use for enhanced oil recovery. This study provides vital information about the hybrid NFs as an alternative injection fluid for EOR applications.