Geochemical characteristics of upper Jurassic carbonate reservoir bitumen in the Eastern Kopeh-Dagh, NE Iran

ABSTRACT

Geochemical characteristics of solid bitumen in Upper Jurassic carbonate reservoir are investigated. Aromatic maturity parameters indicate peak to late oil window level of maturity for the bitumen samples. Regular sterane distributions, conical variable (CV), plots of δ¹³C_Sat versus δ¹³C_Aro and Pr/nC₁₇ against Ph/n_C18, predominance of C₂₃ tricyclic terpane, ratios of steranes/hopanes and C₂₃/C₂₁ tricyclic terpane indicate charging from clastic-rich anoxic marine source rocks. Ratios of C₂₉/C₃₀ hopane, Ts/Ts+ Tm, C₂₄ tetracyclic terpane/C_20-26 tricyclic terpanes and plot of C₂₂/C₂₁ versus C₂₄/C₂₃ tricyclic terpanes show influences of carbonate/marl facies. All these would throw crucial guiding light on the interpretation of the future exploration.

KEYWORDS:

• Biomarker
• bitumen
• carbonate reservoir
• eastern kopeh-dagh
• thermal maturity

Acknowledgments

The authors would like to extend their thanks to the Exploration Directorate of the National Iranian Oil Company (NIOC) for providing the samples and the financial support of the project. Sincere thanks are also given to Petroleum Geology and Geochemistry Research Center (PGGRC) of Shahid Chamran University of Ahvaz for providing the laboratory services. The invaluable help of the anonymous reviewers of this manuscript, which their ideas and comments improved the manuscript, is also acknowledged.