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.
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