Effect of nanoparticles/nanofluids on the rheology of heavy crude oil and its mobility on porous media at reservoir conditions

In this work, we evaluate the effect of nanoparticles and nanofluids as viscosity reducers for heavy crude oil (HO). The effect of alumina, silica and acidic silica nanoparticles was evaluated through n-C7 asphaltene adsorption and aggregation tests using UV-vis spectrophotometry and dynamic light scattering. The nanoparticles of acidic silica were used to prepare a water-based nanofluid at different concentrations in distilled water, and also with the addition of 2.0 wt% of a non-ionic surfactant. The shear rheological response was obtained as function of nanoparticle concentration, temperature (from 298 to 323 K) and shear rate (ranging from 0 to 100 s−1). Experimental results indicate that increasing the concentration of nanoparticles in the mixture, up to 10,000 ppm, leads to a viscosity reduction of approximately 90% in comparison with the nanoparticle-free crude oil. At higher concentration of nanoparticles, the effectiveness of the heavy-oil viscosity reduction diminishes. Rheological tests showed a non-Newtonian behavior for the mixtures tested at 298 K. However, as the temperature reaches 323 K the specimens behave in a Newtonian fashion. Coreflooding tests were conducted under typical reservoir conditions of pore and overburden pressures, i.e. 2600 and 3600 psi, respectively, and at 360 K. Results indicate that the addition of nanoparticles increases the heavy oil mobility and leads to an improvement in oil recovery of roughly 16%.