Key words: South-Caspian basin, oil-and-gas content, avalanche sedimentogenesis, progradation, geotemperature conditions, deep depth.
The unique South Caspian basin, differing fr om internal and marginal seas by a number of parameters and indicators, is formed as a result of the lithosphere evolution. Study of the hydrocarbons ontogenesis processes indicates that the pool is all-sufficient evolutionary system. Phase transformations of the organic matter in the conditions of the closed physicochemical system create abnormally high pore pressures and provide the initial stage of hydrocarbons emigration beyond argillaceous mass, in reservoirs and fractured zones. The principal difference of the processes of deep oil and gas formation is connected to the hindered mass transfer and physicochemical properties of rocks and fluids, which in relevant thermodynamic conditions represent a single mining solution. Significant subvertical and subhorizontal decompressed geological bodies, essentially representing a new class of geological structures, are revealed in the Caspian Basin. Most of them on the surface are associated with large mud volcanoes, with focused intense shows of hydrocarbons, which are logically to relate with the phase transitions processes of various types. A very important factor is that large accumulations of hydrocarbons are confined to them.
Migration of hydrocarbons fr om fluid-generating intervals and hydrocarbon-generating zones to the pay thickness of South Caspian Basin, occurs against the background of practical absence of infiltration water exchange and significantly limited elision regime. At these depths, the dominant form of the movement of natural fluids is interformational ( between the floors ) pulse-injection subvertical migration along planes of conducting disjunctives, zones of increased fracturing and decompression, eruptives of mud volcanoes , lithofaciesdiscordance and other rocks discontinuities, realizing synchronously with the activation of paleo- and neo-tectonic processes.
South Caspian Basin is multifocal pool, within limits of which several autonomous areas of oil and gas formation with their own areals of distribution and spatial-temporal evolution are established. Areas of hydrocarbon generation are confined to various hypsometric and stratigraphic levels, the lower lim it of the oil and gas formation interval reaches depths of more than 12-15 km, which corresponds to the interval of the Paleogene and Mesozoic sediments, and the upper lim it of the oil window is confined to hypsometric depths of 5-7 km and corresponds to Miocene sediments.
