Study of the Distribution of Microelements in Hydrocarbon Groups of Oil

Information on the expanded microelement composition of oil from various classes has practical significance and is of interest for both scientific research and the development of technological processes for its refining. From a geochemical perspective, data on the features on the quantitative distribution of microelements in oil provide an opportunity to identify its genetic differences for oil exploration tasks. In the petrochemical industry, the results of analysis of microelement composition allow for assessing the oil composition at the production stage and monitoring the quality of the obtained products at different stages of refining. In this study, the distribution of microelements in hydrocarbon groups (SARA groups) was investigated using two samples of commercial oil of Russian origin differing in physicochemical properties (heavy high-viscosity and bituminous super-viscous). The content of microelements in the oil samples, comprising their maltenes and asphaltenes, as well as in paraffinic–naphthenic hydrocarbons, aromatic hydrocarbons and resins, was determined using inductively coupled plasma mass spectrometry. These components, exept for asphaltenes, were isolated from the maltenes part using liquid adsorption chromatography according to the generally accepted research procedure developed by Joint-Stock Company VNII NP. It was found that most of the detected elements are present in the oil samples at levels more than 1.0, 0.1–1.0, and less than 0.1 μg/g. The concentrations of other elements were below the limits of detection (0.3–9 ng/g). On the basis of the results of analysis, it was established that both oils studied are enriched in microelements and belong to the “vanadium” type. The main trends in the distribution of microelements in hydrocarbon groups indicate their concentration within polar polycondensed structures (resins and asphaltenes).