Viscoelastic properties of heavy oils

Rheological low frequency measurements were carried out to analyze the viscoelastic properties of four heavy oil samples. At room conditions, the heavy oil samples exhibit non-Newtonian or viscoelastic behavior since they have a viscous component and an elastic component. The latter becomes very important for temperatures below 30°C, and for seismic to ultrasonic frequencies. Above this temperature, the viscous component increases significantly in comparison to the elastic component, and for seismic frequencies heavy oils can be considered as Newtonian fluids.;A new frequency-temperature dispersion model was derived to address the variation of the complex shear modulus (G*) with frequency and temperature for the heavy oil samples. This model fits the data well for seismic and sonic frequencies but it overpredicts G* at ultrasonic frequencies.;A new viscosity model based on the concept of activation energy was derived to predict viscosity in terms of frequency and temperature for temperatures below 60°C.