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The need to minimize in situ heat loss and reduce steam consumption are the main challenges in using steam injection as an enhanced oil recovery (EOR) method for heavy oil. Nanofluids, with their unique thermophysical characteristics, have been successfully used in redesigned thermal systems for various engineering applications, including EOR operations. In this study, a nanofluid-assisted steam injection approach for the enhanced recovery of heavy oil is investigated where a hot hydrophilic nanofluid (HNF) slug is injected, followed by superheated steam (SHS) in a second slug, to effectively synergize the recovery mechanisms of both EOR agents. Initial core flooding experiments were conducted using ZrO2, TiO2, Fe2O3 and ZnO HNFs for the selection of nanoparticle type, concentration, and injection rate. Hot Formation Water (HFW), instead of HNFs, was used as a reference fluid. Superheated steam flooding was tested, and it significantly outperformed continuous HNF injection which slightly improved IFT and wettability. The proposed nanofluid-assisted steam injection approach was tested using ZrO2 and ZnO for three different HNF/SHS PV ratios. Pressure and temperature profiles were continuously monitored to investigate thermal performance and potential formation damage, however this was not observed. The proposed approach significantly improved oil recovery to a maximum of 68%, using 0.50 PV HNF-ZrO2/0.5 PV SHS, compared with 52.9% if 1.0 PV of SHS had been used. No change in oil composition or water content was observed, suggesting that the observed increase in recovery is due to the thermophysical properties of the hydrophilic nanoparticles which improve the thermal performance of the SHS injection and increase oil mobility. Thus, this study presents a promising first-of-a-kind approach which can substantially reduce steam consumption by up to 50% while also improving oil recovery through the utilization of nanotechnology. |
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