||Institute of Oil and Gas Problems RAS
||Institute of Oil and Gas Problems RAS; Institute of the theory of earthquake prediction and mathematical geophysics RAS
The results of an analysis of the trace element composition of oil in a number of oil-bearing basins, so-called young oils, other caustobiolytes, organic matter and the average composition of the Earth's crust are briefly reviewed. Quantitatively, the tightness of the trace element composition of various oils with the chemical composition of possible sources of trace element in petroleum was compared. The obtained results testify to the model in which the dominant source of trace elements in oils is an organic matter with the fundamentally important role in the naftidogenesis of the ascending flows of the lower crustal fluids.
Materials and methods
The ratio of biogenic and deep processes of naftidogenesis was carried out based on the content of Trace Elements (ТЕ) in the oils of the deposits of the Volga-Ural, West Siberian oil and gas basins, and deposits in Kamchatka. Data were also used for the thermal waters of the Uzon volcano caldera. Significant correlation between the content of TE in the investigated oils, various geo-reservoirs, lower, middle and upper crust and biota was obtained by correlation methods.
An analysis was made of character of the correlation of the trace elements composition of various oils and other caustobioliths with the average chemical composition of organic matter and the lower, middle, and the upper continental crust. The nature of the connection for various investigated basins of naftidogenesis, including the group of the Romashkinskoye deposits, turned out to be close. For all oils, besides the young oils of the Uzon caldera, a closer correlation with the composition of the lower crust was revealed. There is no such trend for young oils of the Uzon caldera in Kamchatka, and for statistically more reliable data on the trace elements composition of the hydrothermal waters of the Uzon caldera; in these cases a closer correlation was found with the average chemical composition of the upper crust.
The results of the obtained analysis support the model for the implementation of massive naftidogenesis according to the scheme of a flow-through non-equilibrium chemical reactor, when the trace elements composition is largely determined by the depth of the formation of upstream flow of the mobilized during dehydration deep waters. Under conditions of a typical continental thermal regime, this level corresponds to the depths of the lower crust. For the active thermal regime of areas of recent volcanism, this level shifts to the area of the middle and the upper crust.