Key words: high-viscosity oil, water-oil emulsions, rheology curves, oscillations and sharp decreases of shear stress, viscosity super anomaly.
This work is devoted to the study of the features of non-traditional flow curves obtained on the rotational viscometers for heavy oil and water-oil emulsions from Timan-Pechora oil fields. It has been found that the oscillations and sharp decreases of shear stress on rheological curves may occur at certain critical values of the shear rate. It was established that the cause of the observed effects is water film separation from the water-oil emulsion on the surface of the viscometer cylinder. Experiments show that the values of the critical shear rate are reduced with temperature decreasing and water phase concentration increasing. For the dewatered oil from any fields such fluctuations and sharp decreases of shear stress were not observed in all studied ranges of temperature and shear rate.
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