Dielectric response as a function of viscosity for two crude oils with different conductivities

Dielectric properties and viscosities of two different crude oils (labelled E and N) and solutions of them diluted in toluene or heptane were measured by frequency domain spectroscopy and rheology, respectively. Crude oils E and N diluted with toluene show a linear trend when plotting conductivity as a function of 1/viscosity. The crude oils diluted with the same amount of heptane show a lower conductivity than those in toluene. These results indicate that the conductivity of crude oil solutions is governed by the aggregation state of the asphaltenes more than their quantity in the crude, since asphaltenes are known to be in a more aggregated state in heptane than in toluene. In order to vary the viscosity while keeping the asphaltene concentration and solvation status constant, conductivity measurements of both crude oils diluted with solutions of polystyrene in toluene were performed. For the results obtained for the polystyrene modified systems, the proportionality between conductivity and 1/viscosity is not valid for low viscosities.