Lithological and geochemical characterization of silurian deposits in the Talbeysky block of Chernyshev ridge
The article presents the results of lithological and geochemical research of Silurian deposits in the Talbeysky block of Chernyshev ridge, which are one of the important objects to exploration for hydrocarbon deposits. Based on the structure and lithological composition of the deposits three series were defined in wells section: sulphate-carbonate, carbonate and argillo-carbonate. The Lower Silurian sulphate-carbonate and carbonate series contain mostly poor source rocks (TOC < 0.3 %, HI - 4-173 mg HC/g TOC). The Upper Silurian argillo-carbonate series contain the source rock with fair and good petroleum potential (TOC - 0.5-6 %, HI - 224-580 mg HC / g TOC). The bitumen contents increases from carbonate to argillo-carbonate rocks and varies 0.01-0.02 % and 0.03-0.16 %, respectively. The distributions of n-alkanes and isoprenoids in the hydrocarbon fraction of the studied bitumens show a marine sapropel organic matter in the initial biomass. The maturity of organic matter in Silurian deposits is main oil generation zone and varies on the studied area, ranging from gradations MK1-2 in the north to MK2-3 in the southern part of Talbeysky block.