Relationships between SARA fractions of conventional oil, heavy oil, natural bitumen and residues

A number of indices generated from SARA analyses data are used for characterization of petroleum mixtures (e.g. colloidal instability index Ic = (As + S)/(R + A) and asphaltene index Ia = (As + R)/(S + A)). Knowledge of relationships between SARA fractions is necessary for selection of indices, understanding of chemical continuum from light to heavy compositions and prediction of properties such as density, viscosity, boiling temperature,...