The addition of 1000 mg/L of SiO₂ nanoparticles simultaneously reduced both viscosity and yield stress of heavy oil.

The nanoparticles interact directly with the asphaltenes and hence with the viscoelastic network.

The presence of nanoparticles in the matrix of heavy oil generates a change in the internal structure of the fluid.

The results obtained confirm that nanoparticles affect the internal structure of heavy oil, by modifying the viscoelastic network of asphaltenes.