--> Recognition of a Tectonically Displaced Infra-Cambrian Source Rock Based on Biological Markers in the Baghewala-1 Oil, India, by K. E. Peters, U. D. Gupta, M. E. Clark, M. A. McCaffrey, and C. Y. Lee; #90986 (1994).

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Abstract: Recognition of a Tectonically Displaced Infra-Cambrian Source Rock Based on Biological Markers in the Baghewala-1 Oil, India

Kenneth E. Peters, Udayan Das Gupta, Michael E. Clark, Mark A. McCaffrey, Cathy Y. Lee

Infra-Cambrian to Cambrian-reservoired, nonbiodegraded oil from the Baghewala-1 well in northwest India is geochemically similar to Paleozoic-reservoired oils derived from carbonate-evaporite facies of the Infra-Cambrian Huqf Group in South Oman. The Baghewala-1 oil shows many of the distinctive features of Huqf-sourced oils, including a strong predominance of C29 steranes, diasteranes, and monoaromatic (MA-) steroids, a very negative stable carbon isotope ratio (-32 per mil), a low pristane/phytane ratio (0.9), low diasteranes, low API gravity (17.6°), and high sulfur (1.2 wt%).

Abundant C29 steranes and MA-steroids in the Baghewala-1 oil are typical of oils from Devonian or older source rocks. The oil also shows a high ratio of 24-isopropylcholestanes to 24-n-propylcholestanes (>1), like the Huqf-sourced oils and Late Proterozoic to Early Cambrian oils from other localities, while younger and older samples show a lower ratio (<0.4). Low pristane/phytane, high sulfur, and elevated C35 homohopanes and gammacerane indicate that the source rock for the oil contained Type IIS kerogen deposited under anoxic, saline to hypersaline conditions. Geochemical evidence for the correlation of the Baghewala-1 oil with the Huqf-sourced oils from Oman and a heavy oil from the Karampur-1 well in Pakistan is consistent with a widespread carbonate-ev porite source rock which may have been contiguous during the Infra-Cambrian, but is now represented by the Huqf Group in Oman, the Saline Series in Pakistan, and possibly the Hormuz Series in Iran.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994