Enhanced Heavy Oil Recovery in Sandstone Cores Using TiO₂ Nanofluids

TLDR

The study employed anatase and amorphous TiO₂ nanoparticles, evaluated their stability across salinities using ζ‑potential and UV–vis, and measured contact angles on sandstone cores to elucidate the wettability changes driving enhanced recovery. Injecting a 0.01 % anatase TiO₂ solution into sandstone cores increased oil recovery from 49 % to 80 %, altered rock wettability from oil‑wet to water‑wet, and deposited uniform nanorods (~60 nm) that improved displacement, though higher concentrations caused pore plugging and further study is needed.

Abstract

Anatase and amorphous TiO2 nanoparticles were used to improve recovery of heavy oil from sandstone cores. Before performing core floods, the stability of nanoparticles at different salinities was tested using ζ potential and ultraviolet–visible (UV–vis) methods. While water recovered only 49% of the oil in the core flood experiments, 0.01% anatase structure solution recovered 80% of the oil after injecting two pore volumes at optimum conditions. To understand the mechanism responsible for improved recovery, contact angle measurements were performed on the rock surface before and after treatment with the nanoparticle solution. Contact angle measurements showed that the rock wettability changed from oil-wet to water-wet conditions after treatment with nanoparticles. In 0.01% concentration, scanning electron microscopy (SEM) results showed homogeneous deposition of nanoparticles onto the core plug surface and a few nanorods with a diameter about 60 nm were observed. Energy-dispersive spectrometry (EDS) confirms diffusion of nanoparticles in porous media and uniform distribution. When the nanoparticle concentration was increased, more nanorods with the same diameter were composed, which resulted in plugging to occur. These results indicated the possibility of TiO2 application in enhanced oil recovery (EOR); however, more investigation is required to overcome multi-nanoparticle deposition onto pores.