Burial History and Hydrocarbon Generation Modeling of the Jurassic-Cretaceous Succession in the Northern Western Desert of Egypt

Abstract

Thermal maturity and hydrocarbon generation modeling of the Jurassic-Cretaceous succession in the Abu Gharadig-Shushan basins show that the dark shale of Khatatba Formation (Middle Jurassic) and the shale of Alam El-Bueib Member (L. Cretaceous) are considered the most potential source rocks for hydrocarbon generation. Biomarker distributions and stable carbon isotope composition of crude oils recovered from Abu Gharadig-Shushan oilfields 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 Cretaceous formations (Alam El-Bueib and Abu Roash-F members) strength the idea of presence of two different source rock intervals for oil generation and entrapments with two levels of thermal maturation. Two different shale source rock types were considered in the 2-D modeling of source rock maturation and hydrocarbon generation and each of them was assigned a specific generation potential. Organic rich shale source rock with excellent potential to generate and expel oil and gas is present in the Middle Jurassic Khatatba Formation that entered the late mature stage of oil and gas generation window at vitrinite reflectance more than 1.35 Ro% during the Late Cretaceous. Meanwhile, a good to fair source rock of Alam El-Bueib Member is located within the early to mid mature stage of oil generation window at vitrinite reflectance 1.0 to less than 1.35 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 Abu Gharadig-Shushan basins.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015