Experimental viscosities of heavy oil mixtures up to 450 K and high pressures using a mercury capillary viscometer

This paper presents an experimental methodology to determine the viscosity reduction of heavy oils with a solvent and to evaluate the effect of temperature upon the viscosity of light and heavy oil mixtures. These viscosities can be used in designing solvent stimulation of wells and input to reservoir simulators for heavy oil recovery processes. The data obtained can also be used to estimate diluent quantities required to reduce oil viscosity for pipeline transportation of heavy oil. We designed a versatile capillary tube viscometer to measure viscosity of single-phase mixtures at high temperatures and pressures. Mercury (Hg) is used to achieve higher-precision measurements by providing an ideal piston effect, particularly for stabilizing fluid flow movement of heavy oils in capillary coils. The principle of the method is to measure the differential pressure given by a pressure transducer from laminar flow of a single-phase fluid along the capillary coils, and to convert it to absolute viscosity by using the Hagen-Poiscuille equation. We measured the viscosity of heavy oil and light hydrocarbon mixtures at temperatures ranging from ambient to 450 K, and at pressures from 100 to 34,000 kPa. The heavy oil sample was taken from Canada's heavy oil reserves, located in northeastern Alberta and western Saskatchewan; and the light oil, used as a viscosity reducer, was n-decane. The results presented in this paper provide valuable methodologies and experimental data of viscosity of heavy oil and n-decane useful for further studies in enhanced oil recovery of heavy oils and for transportation purposes. (C) 2003 Elsevier Science B.V. All rights reserved.