Hydrocarbon source rock potential of the Lower Eocene carbonates from the Abu Darag sub-basin, Gulf of Suez, Egypt: Integrated organic geochemical and petrographic analyses

Abstract

Twenty-four subsurface samples from the Lower Eocene Thebes Formation in the north Gulf of Suez underwent organic geochemical and petrographic analyses. The aim is to evaluate the hydrocarbon source rock potential and understand the organic facies composition of this pre-rift formation, which received little attention. The Thebes Formation is a potential hydrocarbon source rock in the area of the GS 24–1 well with an average TOC of 1.52 wt% (range 0.51–4.23 wt%). The organic geochemical (HI/OI and Pr/Ph vs Pr/n-C17) and petrographic analyses revealed that the organic matter of this conventionally known marine source rock is made up of both marine and terrestrial sources in the Abu Darag sub-basin. The predominant kerogen type II is comprised mainly of liptinitic (dinoflagellate cysts and amorphous organic matter: AOM) and subordinate vitrinitic macerals, which produced mixed cyclo and normal alkanes and some aromatics when subjected to pyrochromatography. The average Tmax value of 428 °C and UV fluorescence of the palynomorphs and AOM indicate that the organic matter has entered the early oil-window stage. The tectonostratigraphic evolution of the Abu Darag sub-basin affected the Thebes Formation source rock quality. More exploration activities across this sub-basin are needed to fully explore the organic facies composition and hydrocarbon potential of the Thebes Formation.