SOURCE ROCK EVALUATION AND PETROLEUM GEOCHEMISTRY, OFFSHORE SW IRAN

A. R. Rabbani1 and M. R. Kamali2

1Department of Mining, Metallurgical and Petroleum Engineering, Amirkabir University of Technology (Polytechnic Tehran), 424 Hafez Ave., PO Box 15875-4413, Tehran, Iran. Author for correspondence, email: Rabbani@aut.ac.ir

2Exploration and Production Research Division, Research Institute of Petroleum Industry, Tehran, Iran.

Mesozoic and Tertiary source rocks and crude oils from six oilfields offshore SW Iran, namely Hendijan, Bahrgansar, Abouzar, Nowruz, Dorood and Foroozan, were studied by means of a variety of organic geochemical techniques. Biomarker characteristics were combined with other geochemical data to identify the source rocks which generated the oil in these fields and to reconstruct their depositional environments, and also to characterize the diagenetic and catagenic processes which have occurred. The analyzed oils show a wide range of densities (19 to 39 API) and high sulphur contents. They were generated by Type II-S organic matter; they are not biodegraded and their maturity level is generally low.

Two main oil groups were identified from statistical analysis and can be correlated with different source rocks using age-specific biomarkers and isotope data. Group 1 oils include those from the Hendijan, Bahrgansar and Abouzar fields and were probably generated by a mid-Cretaceous argillaceous source rock. Group 2 oils include those from the Nowruz, Dorood and Foroozan fields, and originated from Jurassic to Early Cretaceous carbonate-rich source rocks.

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