Enhanced oil recovery using chemical and nanoparticles for heavy oil sandstone reservoirs: Chemical vs nanofluid flooding

• Interaction of nanoparticles , surfactants and polymer in heavy crude oil sandstone reservoirs. • Stability of nanofluid with time as observed by electrostatic interaction . • Understanding oil recovery mechanisms like interfacial tension, emulsification , creaming, wettability alteration and oil displacement. • Potential of emulsion induced by chemicals and nano-emulsion induced by nanofluid towards higher oil recovery. • Highest oil recovery achieved by nanofluid flooding system as compared to chemical flooding system. An enormous amount of trapped residual heavy crude oil that exists inside the reservoir after conventional water flooding can be recovered by enhancing the oil displacement efficiency. This oil displacement inside the rock pores can be governed by the application of chemical flooding schemes. In this investigation, we have examined the efficacy of chemical (surfactant-polymer) and nanofluid (surfactant-polymer-nanoparticles) flooding for recovery of heavy residual crude oil in sandstone reservoirs. Polymer (PAM), four different surfactants (anionic and non-ionic) and SiO 2 nanoparticles (hydrophilic) were examined to understand the synergistic behaviour between chemicals, nanofluids and heavy crude oil. The zeta potential value of nanofluid samples ranges between −60.1 to −36.9 mV after 15 days, indicating long term stability of nanofluid system. Additionally, the average particle size analyses conveyed the negligible sedimentation behaviour as encountered by the nanofluid samples. The reduction in oil–water interfacial tension, extent of emulsification, improved emulsion stability as investigated by creaming index (nano-emulsion vs emulsion), highlighted the potential of chemical and nanofluid flooding towards improved oil recovery factor. Lowest contact angle of 12°–20° as detected by nanofluid further conveys the solid–liquid favourable wettability alteration behaviour. Moreover, core flooding experiments conducted showed improved residual oil recovery between 20–22 % original oil in place (OOIP) for chemical (surfactant-polymer) combinations and 22–26 % OOIP for nanofluid (surfactant-polymer-nanoparticles) combinations. Finally, an economy analysis was executed to detect the optimum flooding schemes for sandstone oil field reservoirs.