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Experimental data on structural group composition and macro-structural characteristics of hydrocarbons and petroleum high-molecular compounds (PHMC) – resins and asphaltenes – from more than 150 samples of crude oil samples extracted on the oil-fields of Pannonian (Serbia), Volgo-Ural, South-Caspian, West-Kazakhstanian, West-Siberian, and several Eastand Southeast Asian oil-bearing basins are summarized. It was shown that the number of carbon atoms in the highest n-alkane molecules reaches up to 70-71 in Cenozoic, but only 35-40 in Jurassic and Paleozoic oils. Petroleum hybrid naphtheno-aromatic hydrocarbons are compounds with up to six rings to 24 C-atoms in alkyl fragments of molecules. Resin molecules contain, on a mass weighted average, 1-3 structural blocks each consisting of 0-3 aromatic and 0-5 naphthenic rings in such combinations that the total number of cycles in each block does not exceed 5-6. The weight of average molecular masses of resins does not exceed 1000-1500 g/mole. Asphaltenes differ from resins from the same source by larger average numbers of structural blocks in molecules (up to 5), by the predominantly tri- and/or tetracycloaromatic nature of these blocks, by lesser substitution factors of aromatic nuclei and lesser proportions of C-atoms in saturated fragments. The weight of average masses of asphaltene molecules measured by cryoscopy in naphthalene does not exceed 2500 g/mole. Owing to strong intermolecular interactions, PHMC molecules form various associated structures and poly-molecular particles, including quasicrystalline “batches” and multi-batch aggregates, especially in asphaltenes. Through spontaneous decay and formation of such particles the oils have the character of dynamically equilibrium poly-disperse systems. Compositional and structural variations of PHMC were studied depending on the depths at which they occurred, age and lithological composition of oil-bearing sediments. Although thermal histories are not considered here, clear regularities are established. PHMC, consisting of chemically labile hetero-organic substances, under any bedded conditions are subjected to compositional and structural transformations which are more rapid and substantial as compared with petroleum hydrocarbons.

Principal Regularities in Compositions and Structures of High-Molecular Compounds from Crude Oils and Natural Bitumens