Features of physical-chemical properties of oil as indicators of oil systems (on example of the Permian arch)

The physical-chemical properties of the oil of the Permian Arch oil fields are considered. Based on 838 oil samples from seven Paleozoic gas and oil complexes, ranges of physical-chemical indicators, including density, sulfur, nitrogen, resins, asphaltenes, paraffins and metalloporphyrins, were established. The physical-chemical characteristics of oil are considered as identifiers of the conditions for the formation of oil and gas potential. By performing cluster analysis based on 353 samples, five homogeneous physical-chemical groups of oil (clusters) were identified. The properties of oil of oil and gas complexes and clusters are presented in the "box plot" diagrams. The interpretation of the data was carried out taking into account the ideas about the possible formation of the oil and gas potential of the Permian arch due to three oil systems - "riphean", "devonian terrigenous" and "domanic". The different composition of oil within the field ("diversity of properties") may indicate the features of hypergenic transformations of the composition of oil, as well as possible migration from several generation zones at different time stages. The relatively homogeneous properties of the oil at the Yarinsko-Kamennolozhskoye and Osinskoye fields are interpreted as the result of generation in sources that are productive in volume and intensive in time, and according to the characteristics of the physical-chemical clusters probably belonging to different zones of generation of the "domanic" system.