Hydrocarbon potential of Eocene and Oligocene-Miocene source rocks of the Paratethys

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Abstract

The Paratethys area extends from Switzerland to the shores of Kazachstan and hosts a significant number of petroleum provinces. Many of these provinces have been charged by Eocene and Oligo-/Miocene source rocks. For this study, four petroleum provinces have been choosen for source rock analysis: the North Alpine Forlend Basin (Germany), the Waschberg Zone (Austria) and the Rioni and Kura basins in Georgia. The results of this thesis show, that the oil-prone Middle Eocene Kuma Formation contains prolific source rocks and may generate up to 2 tons of hydrocarbons per square metre (tHC/m²) in the Rioni Basin (Georgia). This implies that the Kuma Formation may be an additional source rock in the eastern Black Sea and the entire Caucasus area. Nevertheless, the Oligo-/Lower Miocene source rocks (e.g. Schöneck Formation, Menilite Formation, Maikop Group) are considered the most important source rocks of the Paratethys. Due to the vast extension of the Paratethys and differing depositional environments, the source rock potential of the Oligo-/Lower Miocene source rocks varies laterally. In the North Alpine Foreland Basin, which belongs to the Western and Central Paratethys, the Lower Oligocene Schöneck and Dynow formations are the most prolific source rocks. These rocks have previously been studied in detail in the Austrian part of the basin, but the petroleum potential in the Bavarian part of the basin remained underexplored. Detailed investigations of core material show, that the succession in western and eastern Bavaria is similar to that in Austria and that the highest TOC contents occur in the shaly upper part of the Schöneck Formation. Together, Schöneck and Dynow formations in the Bavaria can generate up to 0.5 tHC/m². The Oligocene succession in the Waschberg Zone, which connects the Alpine Foreland Basin with the Carpathians in the Central Paratethys, includes the Ottenthal and Thomasl formations. Interestingly, the Lower Oligocene Ottenthal Formation includes abundant diatoms in the Chert and in the Dynow members, similar to the Menilite Formation in the Carpathians, but in contrast to coeval rocks in the Alpine Foreland Basin. The source potential of the Oligocene Ottenthal Formation in the studied outcrop section is low, but the Thomasl Formation includes source rocks with a moderate gas potential in the studied boreholes. The most prominent source rock interval in the Eastern Paratethys is the Oligo-/Miocene Maikop Group. In the Rioni Basin, the potential of the oil-prone source rock is rather high (~4 tHC/m²) and higher than in most other parts of the Eastern Paratethys. In contrast, the hydrocarbon potential of the gas-prone Maikop Group in the Georgian part of the Kura Basin (Tbilisi area) is very low. All of the studied sections were deposited in close proximity to the shore under varying dysoxic to anoxic conditions. The Waschberg Zone and Kura Basin have experienced high detrital input of land plant derived organic matter, whereas the organic matter in the studied part of the North Alpine Foreland Basin and the Rioni Basin is manly derived from marine organisms.

Details

Translated title of the contributionKohlenwasserstoffpotential von eozänen und oligo-/miozänen Muttergesteinen in der Paratethys
Original languageEnglish
QualificationDr.mont.
Awarding Institution
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Publication statusPublished - 2018