Predicting SARA composition of crude oil by means of NMR

Five crude oils with a wide range of API gravities were characterized by means of nuclear magnetic resonance (1H NMR and 13C NMR) and SARA (saturates, aromatics, resins, and asphaltenes) composition. From NMR analyses, the concentrations of aromatic-hydrogen (Har) and aromatic-carbon (Car) were obtained, with which the corresponding aromaticity factors FHA and FCA were calculated. Aromaticity factors were used to develop correlations to predict the SARA concentration of crude oils. The developed correlations showed good accuracy when comparing experimental and calculated values.