The review discusses currently relevant methods for studying petroleum resins. A significant proportion of the research work deals with the study of resins in heavy oils, for which experimental approaches have been systematized and the possibilities and limitations of the mass spectrometric, spectroscopic, X-ray, and chromatographic methods have been discussed. Published data on the effect of resins on the stability of asphaltenes in heavy oils and other petroleum stocks has been analyzed. In addition to experimental approaches, an important factor for understanding the role of resins in the aggregation of asphaltenes is studying their intermolecular interactions using quantum-mechanical calculations. Commonly known approaches to the concentration, fractionation, and purification of heteroatomic petroleum components from heavy oil resins using extraction and chromatographic methods for the isolation of chemical compounds from complex multicomponent mixtures have also been considered.

Features of changes in the content of nickel and vanadium in heavy oils and their asphaltenes are shown for various fields of Volga-Ural region (Russia). The change in the content of vanadyl complexes in the studied asphaltenes upon increase of vanadium content was demonstrated. Several polar solvents (acetone, N,N-dimethylformamide, isopropanol, acetonitrile) are compared as extractants to obtain crude extracts of vanadyl porphyrins from asphaltenes with vanadium content of 0.44 wt%. The opportunity of more efficient extraction of vanadyl porphyrins from asphaltenes is shown by deposition extraction method, particularly when using N,N-dimethylformamide. Absorption spectra and matrix-assisted laser desorption/ionization (MALDI) mass spectra of the extracts obtained were analyzed. For extracts with maximum content of vanadyl porphyrins, the presence of mainly etio- and deoxophylloerythroetioporphyrins was revealed. It was shown that proportion of etio-type vanadyl porphyrins does not exceed 75% of the amount of porphyrins of DPEP-type. A maximum of molecular weight distribution in both types falls on a homologue of vanadyl porphyrin C₃₁ containing nine carbon atoms in the alkyl substituents.

The presented review considers the currently relevant methods for studying petroleum porphyrins. For this purpose, the experimental approaches used during the investigation of the structure,...

The features of the distribution of vanadium and nickel between asphaltenes and resins have been revealed using heavy oils from Tatarstan and Samara oblast oilfields as an example. It has been shown that depending on the V and Ni content in asphaltenes and resins, heavy oils of different productive plays are divided into two separate groups. An increase in the V or Ni content of heavy oils is accompanied by an increase in the concentration of the respective metal in asphaltenes and resins. The intervals of variation in the V and Ni content of asphaltenes and resins of the oils attributed to each group have been determined. As the V concentration in asphaltenes increases, the V/Ni ratio also increases, a feature that is not characteristic of resins.