Rheological behavior from light to heavy oils: construction of master curves

Abstract

"In this work, the rheological behavior of heavy and light stabilized (dead) oils is presented. The viscosity measurements were carried out in two different apparatuses to ensure the repetitiveness and accuracy: a Stabinger viscometer and an Ares G2 strain-controlled rheometer. The samples were previously conditioned with an established methodology. For heavy oils, shear thinning was observed. The zero shear viscosity appears to correlate with the American Petroleum Institute (API) gravity for the case of light oils. However, for heavy oils, the viscosity definitively does not correlate with the API gravity. For example, the viscosity of fluids with an API gravity of around 12° may differ up to a full order of magnitude because of differences in the molecular structure. Saturate, aromatic, resin, and asphaltene analysis is also reported. Viscosity master curves were used to characterize oils. They were produced by applying the time–temperature superposition principle to the isothermal shear rate sweeps. The Williams, Landel, and Ferry equation was used to correlate the shift factor with the temperature. Rheological curves for all of the oils were quite reproduced with this method in all of the operational range."