De-emulsification and gravity separation of micro-emulsion produced with enhanced oil recovery chemicals flooding

The present study investigates the effect of TiO2 nanoparticles on the stability of Enhanced Oil Recovery (EOR)-produced stable emulsion. The chemical precipitation method is used to synthesize TiO2 nanoparticles, and their properties were determined using various analytical characterization techniques such as X-ray Diffraction (XRD), High-Resolution Transmission Electron Microscopy (HRTEM), and Field Emission Scanning Electron Microscopy (FESEM). The effect of TiO2 nanoparticles is evaluated by measuring oil/water (o/w) separation, rag layer formation, oil droplet size, and zeta potential of the residual EOR produced emulsion. The laser scattering technique is used to determine the o/w separation. The results showed that spherical-shaped anatase phase TiO2 nanoparticles were produced with an average particle size of 122 nm. The TiO2 nanoparticles had a positive effect on o/w separation and the clarity of the separated water. The separated aqueous phases� clarity is 75 and 45 with and without TiO2 nanoparticles, respectively. Laser scattering analysis revealed enhanced light transmission in the presence of TiO2 nanoparticles, suggesting higher o/w separation of the ASP-produced emulsion. The overall increase in the o/w separation was recorded to be 19 in the presence of TiO2 nanoparticles, indicating a decrease in the stability of ASP-produced emulsion. This decrease in the stability can be attributed to the improved coalescence� action between the adjacent oil droplets and improved behavior of o/w interfacial film. An observable difference was found between the oil droplet size before and after the addition of TiO2 nanoparticles, where the oil droplet size increased from 3 µm to 35 µm. A similar trend of zeta potential is also noticed in the presence of TiO2 nanoparticles. Zeta potential was �13 mV to �7 mV, which is in the unstable emulsion range. Overall, the o/w separation is enhanced by introducing TiO2 nanoparticles into ASP-produced stable emulsion. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.