hydrocarbons

Corrosion and regeneration types of plagioclase albitization have been determined in a terrigenous complex of productive reservoirs within the cover; this reflects two settings of tectonic-hydrothermal activation in a riftogenic sedimentary basin. Under the pulsating stress conditions (geodynamic anomalies), all plagioclases experience corrosion and, consequently, deanorthitization, with formation of authigenic albite foraminated crystals.

The Precaspian depression subsoil geothermal mode characteristics result not only from presence of the huge evaporite formations and salt dome tectonics, but also from the depth structure of its no granite crust and underlying lithospheric mantle. The current heat flow is primarily of mantle origin and correlates with the HC, helium and other mobile components deep fluid flow.

The anomalous characteristics of the Astrakhan Arch crustal structure were revealed during the seismic data interpretation. They indicate plastic deformations of the lower crust at the sites of its fluidization, manifestation of the waveguide and enhanced permeability zone properties in the upper crust in the ways of the fluid flow. The unique Astrakhan gas condensate field, localized in the carbonate platform of the Middle Carboniferous age at a depth of 4.0 – 4.5 km, was formed in the area of HC-containing deep fluid discharge

Reliable isolation of the Bazhenov-Abalak complex of the Krasnoleninskoye field, ensuring its productivity, was provided by the appearance of secondary (hydrothermal) screens in underlying rocks of the Tyumen Suite. This was reflected in the sealing of the intergranular space of sandstones, silty sandstones and other rocks of the Tyumen suite with regenerative quartz, minerals of silica, and rarely sulphates and carbonates.

The article is devoted to the role of algal material of the Bazhenov suite in the the formation of authigenic dolomite. Authigenic dolomite could form in the environment of convergence of two processes: hydrothermal («wedging out» in the rear zones) and catagenetic (background) generated by conductive heat transfer. The development of the algal dolomite in situ shows that the source rocks experienced the stage of intensive (final) hydrocarbons generation.

To assess the influence of zeolite group minerals on the migration of reservoir fluids in terrigenous deposits, complex (X-ray and gas-geochemical) studies of core material in the Yamal oil and gas region field were conducted. 54 core samples from the Pyakyakhinsky and Yuzhno-Messoyakhsky deposits were studied including 43 zeolitized and 11 non-zeolitized samples.

Our own research data as well as numerous publications of recent years on modern problems of oil potential in the West Siberian oil and gas province were used in this study.