Lithological characteristic of productive deposits The Aptian layer – К1а is mostly formed by clays, in the top part of the section there are layers of brown or black marbles with inclusion of calcite, and grey fine solid sandstones. Clays are black, thick, law-sandy, fat, micaceous, non-marl, sometimes layered with inclusion and thin layers of grey alevrite sand. In the floor of the layer there is a pack of clay, fine sandstones of low thickness that is a productive horizon of the field. The section of the Aptian layer on the site is completely characterized by micro fauna. Thickness of the layer is from 10 m (well No. К-5) to 105 m (wells No. 32, 34) and in average equals 60 – 70 m. The middle layer is J2. Lithologically a section of the Middle-Jurassic is formed by alternation of sand-clay deposits represented by grey, dark grey, and green-grey clays, light grey, dark green and grey fine solid sandstones with layers of law-clays sands. The entire section is characterized by significant content of fine coalified vegetable residues, layers of brown coal. Inclusions of gravel, marbles also occur. Maximum thickness achieves 347 m (well No. 34), minimal thickness is 17 m (well No. K-34).