SOURCE ROCK CHARACTERIZATION IN THE SOUTHERN GULF OF SUEZ PROVINCE, EGYPT BASED ON BIOLOGICAL MARKER DISTRIBUTIONS IN CRUDE OILS

M. A. Younes a* and R. Paul Philp b

a* Geology Department, Moharrem Bek, Faculty of Science, Alexandria University,

Alexandria 21511, Egypt

b School of Geology and Geophysics, 100 E. Boyd St., Norman, University of Oklahoma, Oklahoma 73019, USA

* Corresponding author E-mail: mohamedyounes@hotmail.com

ABSTRACT

The depositional environments and maturity of source rocks in the southern Gulf of Suez have been evaluated using biomarker and isotope data of crude oils derived from a variety of source rock types of different geological ages. Two oils families were identified and are referred to as types A and B. Type A oils were characterized by a predominance of oleanane and relatively low gammacerane concentrations suggesting that this group of oils was derived from a terrigenous source rock with a significant input of angiosperm land plant material, deposited within the marginally mature syn-rift Lower Miocene Rudeis Shale. By contrast, type B oils were distinguished by a predominance of gammacerane and relatively low oleanane concentrations, suggesting that they were generated from mature marine carbonate source rocks within the Upper Cretaceous Brown Limestone and Middle Eocene Thebes Formation. Maturity parameters including various sterane isomerisation distributions (C29α/(α+ααα), C29ααα20S/(S+R) and TAS/(TAS+MAS)) and aromatic sulphur compound ratios (such as 4-MDBT/1-MDBT, 4,6-/1,4-DMDBT, 2,4-/1,4-DMDBT and the DBT/Phenanthrenes) further support the higher thermal maturity of type B oils relative to type A oils. Biomarker variability within the two oil groups presumably reflects the hypothesis that there exist's two source rock types, which in turn the presence of two independent petroleum systems for oil generation, maturation and entrapment consistent with the pre-rift and syn-rift tectonic sequences of the Gulf of Suez.

 JPG Home (opens in this window)