Synthesis of thiol and dodecyl functionalized silica nanoparticles to stabilize Pickering emulsion for enhanced oil recovery

In recent years, silica nanoparticles (SNPs) attracted increasing attention in across various fields, especially in enhancing oil recovery (EOR). Herein, the thiol and dodecyl functionalized silica nanoparticles (fSNPs) grafted with different molar ratios of 3-mercaptopropyl trimethoxy-silane (KH590)/dodecyl trimethoxysilane (DTMS) (1:0, 1:0.2, 1:0.4, 1:0.8, 1:1.6 and 1:4.0) were successfully synthesized via a facile two-step method and subsequently employed to stabilize emulsions for EOR. The SNPs were characterized by the Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectrometer (EDS), thermogravimetric analysis (TGA) and transmission electron microscope (TEM). The water contact angle and interfacial tension (IFT) measurements confirmed the amphiphilicity of the fSNPs. Notably, the fSNPs (1:1.6) grafted with a moderate molar ratio of KH590/DTMS significantly decreased the IFT of n-octane/water interface from 51.0 mN/m to 15.0 mN/m. Both the optical microscopy and static multiple light scattering were utilized for systematical stability evaluation of the fSNPs-stabilized emulsions. The fSNPs (1:1.6) stabilized emulsion exhibited excellent stability and remarkable resifstance to temperature and salinity, which should be attributed to the rigid interfacial film generated by the amphiphilic fSNPs. Moreover, core-flooding experiments demonstrated that the fSNPs (1:1.6)-stabilized emulsion effectively plugged the pore throats and enhanced oil recovery by 18.63 %, confirming its excellent potential in EOR applications.