Synthesis of a novel carbon-based nano-emulsifier and its application in viscosity reduction of emulsified Jurassic oil in the Sichuan Basin

Abstract

A study was undertaken into the emulsification and viscosity reduction processes of crude oil originating from the Jurassic formation of the Sichuan Basin. Central to this investigation was the successful synthesis of a carbon-based nano emulsifier named GOPH, utilizing graphene oxide as substrate and hydrophilic alkyl glycidyl ether and polyoxyethylene ether as modifiers. The structural integrity of this nano-emulsifier was comprehensively characterized via Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. Notably, GOPH nanofluids exhibited a remarkable merit in decreasing the oil/water interfacial tension from 31.96 mN m⁻¹ to a low value of 9.76 mN m⁻¹ with a critical concentration of 45 ppm. Moreover, interfacial film folding experiments revealed that GOPH nanoparticles “jammed” at the oil–water interface, forming a robust film. When Jurassic crude oil was the oil phase, and GOPH nanofluids were introduced into the water phase, the crude oil was successfully induced to form a low-viscosity oil-in-water (O/W) emulsion. Emulsion droplet size and viscosity measurements demonstrated that this emulsion possessed small size distributions with remarkable stability, achieving a viscosity reduction of up to 91.6% at a water content of 80%. The underlying mechanism for this phenomenon mainly lies in the interaction between the carbon-based nano-emulsifier and asphaltene, which form a composite unit, enabling the construction of a flexible interfacial film that significantly stabilizes the O/W emulsion.