Density and Refractive Index of Petroleum, Cuts, and Mixtures

Abstract

Densities and refractive indices were measured for native crude oils, distillation cuts, and thermo- and hydrocracked oils at 20 °C and for some samples up to 60 °C, all at atmospheric pressure. These data as well as pure component and crude oil data from the literature were used to develop correlations between the following: the refractive index function (FRI) and density; the thermal and FRI expansion coefficients; and the binary interaction parameters used in mixing rules for the density and FRI of mixtures. The density (or FRI) of the components (or liquids treated as a single component) were both correlated to within 2%. The density (or FRI) of a mixture was fitted also to within 2% using mixing rules with only the known component density (or FRI) at 20 °C as the input. The mixture density (or FRI) can be predicted to within 4% using only the correlated component density (or FRI) at 20 °C. The correlations have yet to be tested at temperatures above 60 °C and pressures above atmospheric.