The formation of the principal hydrocarbon resource base of Eastern Azerbaijan is predominantly associated with deeply buried source kitchens within the Middle Eocene to Upper Miocene succession of the South Caspian Basin offshore area. Analogues of these deposits are widely distributed within uplifted onshore structural zones, where they crop out or occur at relatively shallow depths. Geochemical investigation of outcrop samples and rock fragments from mud volcano ejecta revealed that the Middle Eocene (Middle Koun Formation) and Middle-Upper Miocene (Diatom Formation) oil shales are characterized by exceptionally high organic carbon content. The Oligocene-Miocene Maikop Series, traditionally regarded as the principal source rocks of the region, are markedly inferior to these strata in terms of organic matter enrichment. Rock-Eval pyrolysis, thermogravimetric analysis, and kinetic modeling confirm that the Eocene and Diatom shales contain a Type II oil-generating kerogen characterized by low activation energy and active stepwise degradation. The Maikop shales are source rocks with a predominance of Type III kerogen, the degradation of which requires high activation energies and exhibits gas-generating potential. The mineral composition of the samples, characterized by a low degree of illitization, and FTIR spectroscopy data indicating the pronounced presence of long-chain aliphatic compounds, point to the low thermal maturity of the kerogen, which is corroborated by petrographic analysis results. Microscopic investigations and pyrolysis data suggest that shale oil may be retained within the kerogen matrix in an adsorbed or swollen state. The integration of geological and geochemical parameters that characterize the occurrence of immature, high-carbon strata with an effective thickness of up to 40 m at depths of up to 4 km confirms the high potential of their thermal conversion to synthetic hydrocarbons. The research results form a scientific basis for future projects on the development of unconventional hydrocarbons in oil shale strata.
