In last decade, a number of papers about nanoparticles studies have been published related to its benefit for oil and gas industries. Some of them discussed about the potential of nanoparticles for enhanced oil recovery (EOR) in the laboratory scale. One of possible EOR mechanisms of nanofluids has been described as disjoining pressure gradient (Chengara, 2004, and Wasan, 2011). The benefit of using silica nanoparticles was explained by Miranda (2012). Hence, the present study objective is to investigate the potential of hydrophilic silica nanoparticles suspension as enhanced oil recovery agent and find out the main mechanisms of nanofluids for EOR.

In this study, hydrophilic nanoparticles with average particle size of 7 nm were used in both visualization glass micromodel flooding experiments and core flooding experiments. A water-wet transparent glass micromodel and Berea sandstone cores with 300–400 mD permeability were used as porous medium. Synthetic brine was used as disperse fluid for nanoparticles. In order to investigate the recovery mechanisms of nanofluids, interfacial tension (IFT) and contact angle between different concentration nanofluids and crude oil have been measured by using spinning drop and pendent drop methods.

The experimental results indicate that the nanofluids can reduce the IFT between water phase and oil phase and make the solid surface more water wet. In the visualization glass micromodel flooding experiments, it was observed that nanofluids can release oil drops trapped by capillary pressure, while the high concentration nanofluids stabilized oil-water emulsion. For the core flooding experiments, nanofluids can increase recovery about 4–5% compared to brine flooding. These results indicate that these nanoparticles are potential EOR agents. The future expectation is that nanoparticles could mobilize more oil in the pore network at field scale to improve oil recovery.

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