Hydrocarbon generation habitat of two Cretaceous carbonate source rocks in SE Turkey

C. Soylu1 , M.N. Yalçın2, B. Horsfield3, H.J. Schenk4 and U. Mann5

1Turkish Petroleum Corporation, Research Center, 06520 Ankara, Turkey.

Author for correspondence, email: csoylu@petrol.tpao.gov.tr

2 Istanbul University, Geological Engineering Department, 34850 Avcılar, Istanbul, Turkey. email: mny@istanbul.edu.tr

3 GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany.


4 Am Wald 28, D-52222 Stolberg, Germany. e-mail: H.J.Schenk@gmx.de

5 Forschungszentrum Jülich, ICG-5, D-52425 Jülich, Germany. e-mail: U.Mann@fz-juelich.de

A detailed petroleum geochemical study has been carried out on two Cretaceous carbonate source rock units, the Karababa Formation A Member and the Karabogaz Formation, in the Adiyaman area, SE Turkey. The purpose was to compare the hydrocarbon generation habitat of these two units which appear to be almost identical in terms of their bulk source rock characteristics. Thus, the TOC contents of the Karababa Formation A Member and the Karabogaz Formation are 0.24-2.09 % and 0.20-4.57 %, respectively. Hydrogen Indices are generally greater than 300 mg HC/ g TOC and both units have similar maturity levels. However, the results of pyrolysis-gas chromatographic analyses showed that the organic matter in the Karababa Formation A Member is richer in sulphur compounds, and the presence of sulphur-rich kerogen resulted in the early generation of hydrocarbons from this unit. Both the dominant activation energy and the frequency factor turned out to be lower for the Karababa Formation A Member. Consequently, oil generation in the Karababa Formation A Member proceeds more rapidly for a given temperature history than it does in the

Karabogaz Formation. Moreover, the results of multi-step Py-GC analyses indicated that the composition of hydrocarbons generated in these two carbonate source rocks will be different, particularly during the early stages of maturation. Early-generated oil from the Karababa Formation A Member has the composition of a mature oil, whereas oil from the Karabogaz Formation reaches the same composition at a higher maturity.

JPG Home (opens in this window)