Burial History and Hydrocarbon Generation
Modeling
of the Jurassic-Cretaceous Formations in the Alamein-Shushan Basins, Northern
Western Desert of Egypt
Maturity and petroleum generation modeling
of the Jurassic-Cretaceous
succession in the Alamein-Shushan basins shows that the dark shale of Khatatba
Formation (Middle Jurassic) and the shale of Alam El-Bueib Formation (L.
Cretaceous) are the most potential source rocks for oil and gas generation.
Detailed biological marker and stable carbon analyses of crude oils
representing Alamein, Yidma, North Ras Qattara and Shushan fields revealed two
oil families of different geochemical characteristics. Family-I representing
crude oil produced from Bahariya Formation (Upper Cretaceous) and Family-II is
the crude oil produced from of the Lower Cretaceous formations (Aptian
Dolomite, Razzak Sand and Alam El-Bueib) strength the idea of presence of two
different source rock intervals for oil generation and entrapments with two levels
of thermal maturations. Two different marine shale source rocks were considered
in the 2-D
modeling
of source rock maturation and hydrocarbon generation and
each source rock was assigned specific generation potential. Organic rich
source rock with excellent potential to generate oil is present in the Middle
Jurassic Khatatba Formation entered the overmature to late mature stage of oil
and gas generation window at vitrinite reflectance between 1.0 and 1.3 Ro%
during the Late Cretaceous. Meanwhile, a good to fair source rock of Alam
El-Bueib Formation located within the early to mid mature stage of oil
generation window at vitrinite reflectance 0.6 to 1.0 Ro% during the Late
Eocene. These source rocks could have charged stratigraphic as well as structrural
traps that play an important role during the hydrocarbon accumulation. The
biomarker variability among the two oil families presumably reinforced the
hypothesis that the presence of two independent petroleum systems for oil
generation, maturation and entrapment in the Alamein-Shushan basins.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California