SHALE GAS POTENTIAL OF DNIEPER-DONETS AULACOGEN

Abstract

Prodigious resources of natural gas are connected with tight low-permeability gas reservoirs. They are represented by three genetic types: tight silt-sandstones with low permeability (central-basin gas), coal beds (coal methane) and black shales (shale gas). Their reservoir geology generality and gas reservoir engineering similarity are determined by small dimensions of pore channels (0,01-0,5 mem). Deep genetic similarity of central-basin, coal and shale gas is determined by leading role of capillary phenomena in formation of their fields. As this takes place, the hydropho-bization of low-permeable rocks are of prime importance. Among hydrophobic factors one ought to mention the mobile products of catagenetic (mainly at mesocatagenetic stage) kerogen distillation (thermodestruction of polymer-lipids complexes of sedimentary organic mater (kerogen) represented by oils and resinous-asphaltenes comtpounds mesocatagenetic processes also cause physic-chemical and petrophysic activation of black shales and coals - their transformation into gas tight reservoirs. Black shales play leading (potential-seting) role in the unified system of unconventional natural gas sources Dnieper-Donets aulacogen is characterized by close interrelation of all three genetic types of gas tight reservoirs. Among a number objects promising for shale gas (connected to a variable extent with gas of low-permeable silt-sandstones and coals) should be mentioned the following: Lower Famenian of NW part of Dnieper-Donets depression (shale and also central-basin gas), Upper Visean (Xlla microfaunistic horizon) black shales of Srebnjanska sag (shale gas), Upper Visean and Lower Serpuhovian of Northern outlying districts of Donets basin and Eastern segment of Northern flank of Dnieper-Donets depression (shale gas). Besides the shale gas potential of Lower Permian saliferous formation and Mezozoic black clays of Dnieper-Donets depression are viewed. Close interrelation of shale, central-basin and coal gas must be taken into account in development of trementdous unconventional gas resources ofDonets basin. Within its boundaries the supergigantic field (with practically inexhaustible gas resources) of shale gas occurring below coaliferous deposits.