INTERMEDIATE COMPLEX OF THE NORTHERN PART OF WESTERN SIBERIA. A POSSIBLE SOURCE OF HYDROCARBONS

Abstract

At present, oil and gas fields as well as numerous oil and gas shows have been found in the intermediate complexes of both young and old platforms. On the basis of lithologic and tectonic indicators, potential oil areas related to the intermediate complex of Western Siberia have been contoured. It is believed that the oil and gas occurring in the intermediate complexes are not genetically related to the platform sediments. In the northern part of the lowland direct geochemical studies of hydrocarbon generating potential and hydrocarbon resources of the intermediate complex are not possible. There is, however, another type of geochemical indicators of hydrocarbon-generating processes in deep horizons - the isotopic characteristics of gases. On the basis of isotopic data, one can conclude that in the northern part of Western Siberia the generation and, possibly, concentration of hydrocarbons took place within the intermediate complex. The regionalization of oil generation is also confirmed by geochemical criteria. Isotopic analysis also indicate vertical migration of hydrocarbons from the intermediate complex into the Mesozoic sequence along faults and fractures.