Elucidating the Nanoparticle–Asphaltene–Resin Interactions and Their Effect on Heavy Crude Oil Viscosity Changes

Recently, nanotechnology has shown potential in reducing the viscosity of heavy crude oil. However, there are some conditions under which the application of technology is unsuccessful. This work aims to identify the rheological behavior of heavy crude oils with different resins and asphaltene content, to define in which type of heavy crude oil based on this ratio the application of nanotechnology is successful, i.e., where does not produce viscosity reductions in the crude oil, by evaluating different resins/asphaltenes ratios (R/A) in the presence of SiO 2 nanoparticles and their impact on the viscosity of heavy crude oil. Two reconstituted crude oils, heavy oil (HO) and extra heavy oil (EHO), with varying resin contents, were prepared by the isolation and subsequent addition of asphaltenes, modifying the R/A ratio. SiO 2 nanoparticles with a size of 7 nm and dosage of 1000 mg/L were used to reduce the viscosity of the crude oils. Using steady-state rheology tests, it was possible to determine that the viscosity increased exponentially when the R/A ratio was between 1 and 5 and that the nanoparticles had a viscosity reduction effect for asphaltene contents higher than 5 wt % and R/A ratios lower than 10 for both crude oils. The point of maximum viscosity reduction was obtained at an R/A ratio close to 4, with viscosity reductions between 35 and 40%. For ratios higher than 7.5, adding silica nanoparticles did not positively affect the viscosity change; in contrast, it increased the viscosity of crude oil. These findings could have a positive impact on the design of nanofluids applied to improve the transport conditions of heavy oil and open avenues for further exploration, stimulating interest in the future of the field and the potential for new discoveries.