In oil composition of the Republic of Bashkortostan, along with historically defined metals (V, Ni), two dozen other elements can be found, which are of practical interest in terms of genesis of hydrocarbon fluids, their transformation and determination of migration paths during the geological evolution of the Earth. The article presents the results on adaptation of the method for determination of metals in oil by atomic absorption method with preliminary decomposition of petroleum hydrocarbons in microwave system of mineralization and the application of this approach for oil correlation by trace element composition.
On the basis of obtained data on the content of metals in the fractions of the investigated oil of the western and northern parts of the Republic of Bashkortostan, two groups of characteristic ratios of microelements are proposed (each group contains ten characteristic pairs of metals). In the selection of characteristic ratios, the main role was played by the belonging of metals to a certain fraction of oil, reproducibility over time and upon changing measurement conditions, as well as clear separation of obtained spectra of elements. The first group of metal ratios characterizes the proximity of compositions of individual fractions and oil in general to each other and is associated with primary processes of oil formation, the second group allows to estimate the degree of transformation of oil composition as a result of secondary processes (catagenesis, migration, hypergenesis, biodegradation). This method of correlation allows establishing the proximity of oil with different physicochemical properties and the difference of oil with similar physicochemical properties. The combination developed method of oil correlation with other geochemical methods of research, will allow clarifying geological structure of fields and supplementing the model of formation of oil reserves.
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