*Geology Department, Faculty of Sciences, Ain Shams University, 11566 Abbassia, Cairo, Egypt.
Geochemical analyses of mudstones from wells in the NE offshore Nile Delta suggest that the Early Miocene Qantara Formation has good potential to generate hydrocarbons at the studied locations. Its generating capability and oil–proneness increase northwards, where better organic-matter preservation and a greater contribution from marine sources can be expected. By contrast, the Middle Miocene Sidi Salem Formation has poor to fair potential to generate mixed gas and oil, while the overlying Kafr El Sheikh and Wakar Formations have poor capability to generate gas with minor oil. Based on pyrolysis Tmax and thermal alteration index assessments, the Kafr El Sheikh and Wakar Formations are immature to marginally mature in the study area. The Sidi Salem and Qantara Formations are immature in the southern part of the study area, but are within the oil window in the north, around well Temsah-4.
Biomarker distributions based on GC-MS analyses of two condensate samples from the Wakar and Sidi Salem Formations indicate that hydrocarbons are derived from siliciclastic source rocks containing significant terrestrial material and limited marine organic matter. The condensates were generated during early maturation of Type III kerogen from deeper and more mature source rocks than those encountered in the drilled wells. Geochemical and isotopic data from natural gas produced from the Kafr El Sheikh Formation suggest mixed biogenic and thermogenic sources.