Azra Tutuncu, Shell Exploration and Production Company.

Viscoelastic measurements of four heavy and extra-heavy oil samples were carried out to analyze the dependence of complex viscosity, loss and storage modulus with temperature and frequency. The dynamic rheological tests showed a shear thinning phenomenon typical of non-Newtonian fluids, highly pronounced for seismic and sonic frequencies and for temperatures below 50˚C. The Power-Law method that explains the shear thinning behavior was modified to incorporate the liquid crystal theory and the viscosity dependence on temperature based on the concept of activation energy. An expression was derived to predict complex viscosity based on frequency and temperature changes