Recently,
researchers have proved the application of nanoparticles
(NPs) for enhanced oil recovery (EOR) in ambient temperature. However,
to our knowledge no attempt has been undertaken experimentally to
investigate the influence of NPs on EOR at higher temperatures. In
this study, aluminum oxide (Al2O3), titanium
dioxide (TiO2), and silicon dioxide (SiO2) were
selected for EOR purposes from an intermediate-wet limestone sample
at 26, 40, 50, and 60 °C. These metal NPs were dispersed in deionized
water at concentration of 0.005 wt %. First, transportation of
the NPs through limestone was evaluated. It was found that Al2O3 (8.2%) had the lowest and TiO2 (27.8%)
and SiO2 (43.4%) had the highest adsorption on the limestone.
Consequently, wettability of the limestone was changed into water-wet
through NPs adsorption. The contact angle in the presence of Al2O3, TiO2, and SiO2 nanofluids
was measured as 71° ± 2°, 57° ± 2°,
and 26° ± 2°, respectively. Interfacial tension was
also noticeably reduced with these nanofluids at all temperatures.
Al2O3 and TiO2 nanofluids respectively
demonstrated better results in EOR compared to SiO2 at
all temperatures. Reduction of capillary force was the main reason
for EOR via the nanofluids. Moreover, a considerable reduction in
oil viscosity was observed after Al2O3 and TiO2 nanofluids flooding at 50 and 60 °C.