Petroleum System Evaluation: Hydrocarbon Potential and Basin Dynamics in Abu Darag Sub-Basin, Northern Gulf of Suez (Egypt)

Abstract

The Abu Darag sub-basin in Egypt is a significant hydrocarbon province. This study provides the first thorough evaluation of the petroleum system in the Northern Gulf of Suez, specifically targeting regions with tectonically influenced paleo highs. The research is novel in its holistic approach, linking tectonic activity with hydrocarbon generation and accumulation, particularly in the Nukhul Formation. In the NDARAG-1 well, with the Nukhul Formation serving as its main reservoir, petrophysical analysis estimates an average net pay of 126 ft in the Nukhul Formation, with 19% average shale volume, 17% average effective porosity, and 57% average water saturation. Geochemical evaluation of the shales in the Thebes, Matulla, Raha, and Nubia-A formations indicate source rock potential ranging from fair to very good, with TOC values between 0.5 wt% and 5.4 wt%. The burial history model outlines gradual subsidence and sediment deposition from the Paleozoic to the Early Cretaceous, followed by significant compression and uplift during the Late Cretaceous. Early oil generation in the Nubia-A Lower shales began during the Early Cretaceous (~132 Ma) at a depth of 4000 ft while it occurred in the Early Miocene (~22 Ma) at a depth of 7400 ft. The Nubia-A Lower Member is identified as the key source rock, with vitrinite reflectance values above 0.70%. Continuous subsidence during the Eocene led to the deposition of the Nukhul, Rudeis, and Kareem formations. Oil generation in the Nubia-A Lower shales occurred during both the Early Cretaceous and Early Miocene. The main risk to hydrocarbon accumulation in the Abu Darag sub-basin is related to potential seal failures due to the erosion and/or non-deposition of the Belayim, South Gharib, and Zeit evaporites. The only producing wells are situated in the northwest of the study area, where conditions are conducive to hydrocarbon entrapment and preservation, and secondary migration has occurred in a northwestward direction.