Shear modulus of heavy oils: Confinement effects in rheometer measurements

Abstract

Abstract Viscosity of heavy oil constitutes an important property that governs the productivity of these reservoirs. The viscosity of these crude oils is highly dependent on many variables like temperature, frequency, and strain amplitude. In this paper we show that viscosity measurements of heavy oils can also depend on a measurement variable like the gap thickness in a parallel plate rheometer. In this paper we measured how the confinement of heavy oils between parallel plates induces an increase in shear modulus. We propose that the increase in shear modulus can be linked to the surface-active nature of heavy oils that can cause re-orientation of the molecules at the surface of the plates and producing a measurable increase in the shear modulus. The findings were observed in three different samples of heavy oils. The results of this work have major implications in the measurement of viscosity of heavy oils but more importantly in the flow of heavy oils in porous media.