Ultrasound-assisted nanofluid flooding to enhance heavy oil recovery in a simulated porous media

Herein thermally treated empty fruit bunch SiO₂ nanoparticles (EFBSNP) was produced by ultrasound-assisted wet-milling and their effectiveness in enhancing cavitation effect of ultrasound to improve heavy oil recovery was evaluated. Empty fruit bunch ash (EFBA) was thermally treated to enhance its SiO₂ content. Surface properties and size distribution of EFBSNP were studied using transmission electron microscopy and dynamic light scattering. X-ray diffractometer identified the crystal phase, the active group was ascertain using Fourier-transform infrared spectroscopy and thermal stability was established by differential scanning calorimetry. Moreover, the surface chemical composition was determined by X-ray photoelectron spectroscopy. The ability of empty fruit bunch SiO₂ nanofluid (EFBSNF) to absorb ultrasound in heavy oil and the impact of ultrasound assisted EFBSNF flooding to enhance oil recovery of heavy oil was assessed. The microstructure analysis revealed EFBSNP of size ranges 17.78–115.38 nm with a purity of 94%. EFBSNF assisted ultrasound decreased interfacial tension to 0.2 mN/m, thus mobilizing the trapped oil droplet in the pores effectively. Ultrasound assisted EFBSNF flooding increased oil recovery by 44.33% compared to 26.33% without ultrasound.     

Mimic oil recovery with a SDBS–dodecane–silica gel system

The wettability of the solid powder of silica gel was determined via a modified Washburn equation expressed as contact angles. The interfacial tension (γ) between the dodecane and the dilute sodium dodecyl benzene sulfonate (SDBS) aqueous solution was obtained using the spinning drop (γ<10 mN m⁻¹) or drop volume methods (γ>10 mN m⁻¹). Contact angle changes for SDBS aqueous solutions on the surface of a silica gel powder were studied. The average aggregation number of SDBS micelles in aqueous solution was determined using the fluorescence quenching method. The relationship between the wettability of the powder surface, the critical micelle concentration (CMC) of SDBS and the mimic oil recovery of the resident oil on the powder surface has been explored. It has been found that good residual oil recovery was achieved by surface wettability changes at the interfacial tensions around 4–5 mN m⁻¹, which is far from the ‘ultra low’ condition (≤10⁻³ mN m⁻¹).