Impact of Metal Oxide Nanoparticles on Enhanced Oil Recovery from Limestone Media at Several Temperatures

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 (Al 2 O 3 ), titanium dioxide (TiO 2 ), and silicon dioxide (SiO 2 ) 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 Al 2 O 3 (8.2%) had the lowest and TiO 2 (27.8%) and SiO 2 (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 Al 2 O 3, TiO 2, and SiO 2 nanofluids was measured as 71° ± 2°, 57° ± 2°, and 26° ± 2°, respectively. Interfacial tension was also noticeably reduced with these nanofluids at all temperatures. Al 2 O 3 and TiO 2 nanofluids respectively demonstrated better results in EOR compared to SiO 2 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 Al 2 O 3 and TiO 2 nanofluids flooding at 50 and 60 °C.