Effect of Organically Modified Nanosilica on the Viscosity and Rheological Behavior of Karamay Heavy Crude Oil

The introduction of nanomaterials into oil-soluble viscosity-reducing agents has attracted attention because of the potential to reduce resistance during the injection process in oil recovery. In this paper, toluene was used as a solvent in nanosilica modification, and modified nanosilica with a uniform dispersion was obtained. A series of nanocomposite viscosity reducers was prepared by reacting different proportions of the modified nanosilica with styrene, butyl methacrylate, and acrylamide. Samples were prepared by mixing the modified nanoparticles with heavy crude oil and investigated with polarized light microscopy, rheological behavior tests, and viscoelasticity tests. The results show that the nanocomposites exhibit the special surface effects and nanoslip effects of nanoparticles and inhibit the formation of fractal aggregates of colloidal asphaltenes. As the amount of modified nanosilica increases, the viscosity-reducing effect improves. The viscoelastic tests indicate that the addition of the viscosity-reducing agent with the nanocomposites has a greater influence on the storage modulus G′ and the loss modulus G″ of the fluid than the addition of the polymer without nanoparticles. The results indicate that the viscosity-reducing agent can cause various degrees of damage to the internal structure of the heavy crude oil, and the viscosity reducers prepared using 500 and 600 ppm nanoparticles have the most significant effect on the viscosity reduction of the oil.