The study of fluid-migration processes in oil-and-gas deposits of the Vankor field

The topicality of this work is conditioned by the necessity of improvement of prospecting and exploration methods of oil and gas deposits for a choice of an optimum mode of exploitation of oil-fields with difficult extractive supplies of hydrocarbons. The aim of work was to obtain a detailed lithological, petrographic, mineralogical, geochemical information about the structure of deep well Vankor 11 drilled in the north-eastern part of Western Siberia and preparation of the preliminary forecast of oil and gas potential of the region using the selected set of methods. As a result of research, it was determined that the dislocation-metasomatic processes are accompanied by destruction and dissolution of original rock and removal of petrogenic components and the formation of the newly formed minerals. It was revealed that the epigenetic transformation of rocks in a well is smainly manifested in the form of secondary mineral formation: the formation of carbonates, quartz and clay minerals. When setting out petrogenic components, pores and interporous channels occur in complex conformal contacts, and, under favorable conditions, a secondary highly porous rocks zone is formed. That is, the formation of porous fractured space rocks begins with sedimentation of precipitation and ends with postsedimentation processes, as a result of the latter there is a redistribution of substances, in particular due to the removal of alkaline and alkaline-earth elements (in particular, calcium, potassium and sodium). The studies found that highly porous rocks are partially present in the following suites of the Lower and Upper Cretaceous of well Vankor-11: Dolgan, Yakovlevskaya, Sukhodudinskaya and Nizhnekhetskaya. However, the formation of oil and gas deposits in deposits of these suites is only possible if there is compacted rock. A limited number of seals in the sediments of Suhodudinskaya and Malahetskaya suites let the hydrocarbon migration in the overlying horizons and contributed to the formation of oil and gas deposits in the favorable structures of deposits of Nizhnekamskaya, Yakovlevskaya and Dolgan suites. Fluid-migration processes with the formation of gas deposits were completed in the sediments of Dolgan suite. Thus, character and intensity of the epigenetic of transformations of rocks, formation of collectors and, eventually, hydrocarbon deposits in an essential degree depend not only on existence of rock collectors and seals, but also on subcurrent hydrocarbonic fluids from the deep horizons in zones of tectonic violations. It is possible that this circumstance is essential when forming oil and gas deposits both in Jurassic and Cretaceous deposits. Yanovstanskaya suite and enriched Corg rocks of Malyshevskaya, Leontyevskaya and Vymskaya suites have a determining value in enriching the fluid streams with hydrocarbons in the process of petroleum source rocks.

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