Lithological characteristics and oil-bearing limestones of the Cherepetskaya horizon tournaisian tier on the territory of the Republic of Tatarstan

The study of the carbonate oil reservoirs of the Cherepetskaya horizon tournaisian tier of the Republic of Tatarstan. It is established that in the context of the Cherepetskaya horizon beds are intercalated three main lithological types of limestones: biocentive zoogenic, phyto-zoogenic and phytogenic. The first two lithotype rocks are oil-saturated reservoirs, and the third refers to rocks of the confining beds. Limestone Cherepetskaya horizon contain heterogeneous composition of water-fluid. At the top of the structural unit of oil enriched with light and medium fractions of hydrocarbons at the bottom - heavy, with a substantial admixture of produced water. This trend indicates the prospects of development of only the upper part of the horizon Cherepetskaya not experienced the process of natural flooding.