Comparative Organic Geochemical Characterization of Paleogene-Neogene Sediments in the South Caspian Basin

In the South Caspian basin source rock studies based on Rock-Eval pyrolysis were carried out using three different types of rock material: cores from wells, outcrop samples and mud volcanic ejectas. Three stratigraphic intervals were considered: Oligocene-Lower Miocene Maykop Series, Middle-Upper Miocene and Lower Pliocene Productive Series. For Oligocene-Lower Miocene interval most numerous are outcrop analyses, with their geochemical characteristic being altered by weathering. For two other intervals the bulk of samples is core material. Core samples and ejectas are shown to be less effected by hypergene factors. Estimates of sediments organic content and their hydrocarbon generative potential depends upon sample size and display appreciable variation between wells, outcrops and mud volcanoes. In the Lower Pliocene samples epigenetic hydrocarbons have been found to make up significant proportion of total organic content of sediments, thus pointing to subvertical migration from depths of oil generation.