Aiming at improved classification of crude oils, naphthalene and phenanthrene isomerization and dealkylation processes were considered in detail as a possible basis to select new maturation parameters. Crude oils originating from the Banat depression (Southeastern Pannonian Basin, Serbia) were used as objects of our study. Four new maturation parameters are proposed in this paper. Two of them are based on dimethylnaphthalene (DMN) and trimethylnaphthalene (TMN) isomerization reactions: DN_x = (1,3-DMN + 1,6-DMN)/(1,4-DMN + 1,5-DMN) and TNy = (1,3,6-TMN + 1,3,7-TMN)/(1,3,5-TMN + 1,4,6-TMN). The other two are based on demethylation of dimethyl-and trimethylphenanthrenes (DMP and TMP) into corresponding methylphenanthrenes (MP): MDR = ΣMP/ΣDMP and MTR = ΣMP/ΣTMP. The new parameters’ advantageous applicability was demonstrated by factor analysis, comparing them with maturation parameters known from literature.

The aim of this work was to study the fractional composition of super-viscous oil resins from the Ashalcha field, as well as the catalytic aquathermolysis product in the presence of a cobalt-containing catalyst precursor and a hydrogen donor. The study was conducted at various durations of thermal steam exposure. In this regard, the work enabled the identification of the distribution of resin fractions. These fractions, obtained by liquid adsorption chromatography, were extracted with individual solvents and their binary mixtures in various ratios. The results of MALDI spectroscopy revealed a decrease in the molecular mass of all resin fractions after catalytic treatment, mainly with a hydrogen donor. However, the elemental analysis data indicated a decrease in the H/C ratio for resin fractions as a result of removing alkyl substituents in resins and asphaltenes. Moreover, the data of ¹H NMR spectroscopy of resin fractions indicated an increase in the aliphatic hydrogen index during catalytic aquathermolysis at the high molecular parts of the resins R3 and R4. Finally, a structural group analysis was carried out in this study, and hypothetical structures of the initial oil resin molecules and aquathermolysis products were constructed as well.

Thermal transformations of petroleum components of paraffin-base heavy crude oil and oils (hydrocarbon concentrate), a mixture of oils and resins (maltenes), and a mixture of oils with asphaltenes isolated from the crude have been studied in order to assess the effect of resins and asphaltenes on the hydrocarbon conversion direction. Thermolysis of samples has been conducted at 450°C for 2 h in the isothermal mode. Data on the material balance of the process have been obtained, and the composition of the gaseous and liquid products of thermolysis has been determined. The gaseous products of thermolysis consist of hydrogen, carbon dioxide, and C–C hydrocarbons. It has been shown that the thermolysis of all the samples is accompanied by the appearance of newly formed resins and asphaltenes. Analysis of the dynamics of changes in the hydrocarbon composition of the liquid thermolysis products has shown that the resins, rather than asphaltenes affect to a greater extent the direction of hydrocarbon cracking reactions.

Thermal transformations of hydrocarbons, resins, and a mixture of hydrocarbons and resins of heavy petroleum from the Usinskoe oilfield (Russia, Komi) have been studied. Data on the material balance of the process and the composition of gaseous and liquid products of thermolysis have been obtained. The structural characteristics of asphaltenes and resins resulting from thermolysis have been investigated, and changes in the hydrocarbon composition of the thermolysis products have been analyzed. It has been shown that the direction of thermal transformations of hydrocarbons changes in the presence of resins. During thermolysis, the resin degradation reactions facilitate the formation of hydrocarbons and polycondensation reactions give rise to asphaltenes.

Influence of the WC/Ni–Cr additive on the cracking of maltenes of naphthenic crude oil from the Usa oil field has been studied. Maltene cracking was carried out at 450°С for 2 h in the isothermal mode. Material balance of cracking, the composition of gaseous products, and the fractional, component, and hydrocarbon compositions of feed maltenes and liquid products of their cracking have been determined. It has been shown that cracking with WC/Ni–Cr gives more gaseous and solid products. In comparison with starting maltenes and the product of their cracking in the absence of the additive, the yield of IBP–360°С distillate fractions increases by factors of 1.6 and 1.4, respectively. It has been found that cracking reactions lead to degradation of resinous components to give low-molecular-weight resins and light hydrocarbons and parallel condensation reactions promote the formation of asphaltenes and solid products. It has been shown that the additive WC/Ni–Cr has cracking properties, as indicated by significant differences in fractional and hydrocarbon compositions of liquid products, and by the fact that the amount of Н₂ and С₁–С₂ hydrocarbon gases in the products of cracking is much higher in the presence than in the absence of WC/Ni–Cr. This difference can be due to degradation of not only resins, but also high-molecular-weight naphthenoaromatic hydrocarbons.

Thermolysis of crude oil at a temperature of 350°C for 1 h with and without aluminosilicates has been conducted in the isothermal regime mode. The composition of liquid and gaseous thermolysis products has been analyzed. The amount of resins and asphaltenes in the liquid products of thermal or thermocatalytic treatment decreases and that of oils increases as compared with the crude oil. The individual composition of saturated hydrocarbons (alkanes, steranes, terpanes) and alkylaromatic compounds (benzenes, naphthalenes, and phenanthrenes homologoues) has been studied. It has been shown that thermolysis increases the amount of thermodynamically more stable m- and p-isomers of alkyltoluenes, and the β-isomers of alkyl-naphthalenes and alkylphenanthrenes. Geochemical parameters for the composition of alkyl substituted benzenes, naphthalenes, and phenanthrenes have been calculated.