Enhancing oil production using silica-based nanofluids: Preparation, stability, and displacement mechanisms

A novel two-step preparation of a silica nanofluid (Si-NF) with potential for light oil recovery is herein presented. It was observed that a Si-NF, prepared by dispersing silica nanoparticles (Si-NPs) in poly(vinyl alcohol) (1%) under carbon dioxide gas bubbling, is stable for 30 days at a temperature as high as 55 °C without any visible sedimentation. Unstable Si-NFs formed siliceous gels whose strength depends on Si-NP load. The spectral characterization revealed that prepared Si-NFs consisted of silanols, carbonyls, and alcohols. As part of an effort to enhance the light oil production (API 31°), 1, 0.5, and 0.1 wt % Si-NPs were injected in waterflooded Berea sandstone at 55 °C. An increase in oil as high as 7.6% was achieved for the Si-NF with the highest Si-NP load (1 wt % Si-NP). Oil production encompassed the discontinuity of Si-NFs, channel plugging, wettability, and interfacial tension alterations.