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Using a complex of physical and chemical methods studied features of the elemental, structural-group, and microelement composition of natural bitumen asphaltenes extracted from bituminous rocks of Tatarstan's Permian deposits. It is an investigated interconnection of value changes of spectral parameters (of aromaticity, oxidation, and aliphatic) characterizing of structural-group composition of original bitumen and asphaltenes. The features of the microelement composition of asphaltenes of bitumen of various types were also revealed. [ABSTRACT FROM AUTHOR]

In this research, four different crude oils from Tatarstan oil fields with wide range of API gravities (from 16.6 to 32.5 °API) were used for hydrogen and carbon nuclear magnetic resonance spectroscopy (H NMR and C NMR) determinations. The hydrogen and carbon aromaticity factors were calculated by using the results of H NMR and C NMR spectroscopy results. The results show that the aromaticity factors were high for heavy crude oils. For predicting SARA fractions, the correlations were developed as a function of aromaticity factors. The developed correlations showed high accuracy for predicting SARA fractions for four crude oils. • The hydrogen and carbon aromaticity factors are increasing with increasing crude oil gravity. • The developed correlations showed high accuracy for predicting SARA fractions for four crude oils. • The maximum error was around 9.4% while the minimum was 0.1% for the developed correlations. [ABSTRACT FROM AUTHOR]