Hydrocarbon Seepage Generation and Migration in the Southern Province from the Gulf of Suez, Egypt: Insight from Biomarker Characteristics and Source Rock Modeling
Mohamed Abdel-Aziz Younes1, T. El-Azhary2, M. Said2
(1) Alexandria University, Alexandria, Egypt (2) N/A, Stratochem, Egypt
Active hydrocarbon seepage in Gebel El-Zeit area, southern Gulf of Suez province is associated with the Quaternary outcrop sediments. The oil seepage occurs in faulted zones on the western flank of the East Zeit Basin. The biomarker properties obtained from Gas Chromatography-Mass Spectrometry (GC-MS) proved that the hydrocarbon seepage possesses geochemical characteristics rich in tricyclic terpanes and extended hopanes with few diasteranes, typical characteristics of oils derived from marine siliciclastic source rocks with angiosperm land plants input as indicated from the higher proportion of oleanane index of 32.65% and low gammacerane index of 6.28%. The maturity parameter based on [20S/(20S+20R)]-C29 aaa cholestane to the hydrocarbon seepage was found to be < 0.5; to indicate that the seepage was generated at relatively low grade thermal maturity. The hydrocarbon seepages correlate with the biomarker properties of Miocene crude oils, which were possibly derived from marine siliciclastic syn-rift Lower Rudeis shales rich in Tertiary angiosperm land plants. The incipient oil generation window is believed to have been generated at vitrinite reflectance in the range Ro%=0.60-0.85 at 3-4 million years before present (Mybp). The source rock distribution allows for extensive lateral and vertical migration through faults that reach the surface. Oil expulsion and migration began during Middle Miocene and still continuing at present in Gebel El-Zeit area. Hydrocarbon seepages may have also migrated from leaking accumulations.