The study of ultralow interfacial tension SiO2-surfactant foam for enhanced oil recovery

Surfactant selection and formulation are key factors in technological and economic success in chemically enhanced oil recovery (cEOR) applications. In this study, the silica nanoparticle (SNP) was added in an ultralow interfacial tension foam (ULIFT), called SNP-ULIFT foam, which was successfully prepared by ternary surfactant systems. The Carboxylate-based extended surfactant (Carboxylate), Dioctyl Sulfosuccinate Sodium salt (AOT), and Sodium Diphenyl Oxide Disulfonate (DODS) at a 0.48:0.48:0.04 wt ratio were conducted as the surfactant system. Remarkable results in the selected surfactant system were observed in terms of the ability to form foaming and ultralow interfacial tension (IFT) at 60 +/- 2 degrees C with the ADNOC crude oil (Abu Dhabi National Oil Company) as model oil. The optimum salinity of the surfactant system was found at 2.5 wt% (8:2 Na:Ca by weight), indicating a minimum IFT of 0.0019 mN/m. The adsorption capacities at the optimum salinity condition of each surfactant in the mixture onto the SNP's surface were 1.4, 7.3 and 19.4 molecule/nm2 for the DODS, Carboxylate and AOT surfactants, respectively; the calculated total surfactant adsorption was 2.6 mg surfactant/ mg nanoparticles. While in the presence of SNP, the surfactant adsorption of the ternary surfactant foam system onto the sand surface was significantly reduced by 16.2% at 200 psi and 60 degrees C when compared with the neat ULIFT foam system. It was remarkably noted that the adsorption of the surfactant onto the SNP surface could result in a reduction of surfactant adsorption onto the sand surface. The oil recovery performance in the core flood by ULIFT foam was the greatest with 43% of Original Oil in Place (OOIP), and it further increased by 13% in the presence of 200 ppm SNP. In addition, the stress and viscosity of ULIFT microemulsion significantly decreased with SNP. This suspension exhibited the most non-Newtonian behavior with shear-thinning behavior over different ranges of shear rate. Therefore, SNP-ULIFT foam with the appropriate surfactant selection was a successful method for improving oil recovery performance.

Automated summary

The study successfully prepared silica nanoparticle (SNP) added ultralow interfacial tension foam (SNP-ULIFT foam) using ternary surfactant systems. The foam exhibited remarkable ability to form foam and ultralow interfacial tension, leading to significant improvement in oil recovery performance in core flood experiments.