Geochemical evidence for a thermogenic oil-associated gas petroleum system for JDT field in Abu El Gharadig basin, Egypt

IF 2.2 4区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of African Earth Sciences Pub Date : 2026-05-01 Epub Date: 2026-01-20 DOI:10.1016/j.jafrearsci.2026.106036

Mohamed A. Agamy , Mahmoud Y. Zein El Din , Mohamed M. El Nady , Walid A. Makled

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Abstract

This study presents a comprehensive geochemical assessment of rock samples and natural gas data to evaluate the petroleum system of the Abu El Gharadig Basin. The investigation focuses on the Upper Cretaceous Abu Roash (C –G) members and Middle Jurassic Khatatba Formation which represent the principal source rocks in the basin. Total organic carbon (TOC) and Rock-Eval pyrolysis analyses reveal significant organic richness, with TOC values reaching up to 3.14 wt%, and hydrogen index (HI) values peaking at 489 mg HC/g TOC indicative of Type II kerogen. This indicates a strong potential for liquid hydrocarbon generation. Thermal maturity parameters including Tmax (430–448 °C) and vitrinite reflectance (R_o = 0.50–0.92 %) confirm that these source rocks lie within the oil window, with deeper intervals approaching peak maturity. Geochemical characterization of natural gas from the Apollonia reservoir further supports this interpretation. The gases are gas associated with oil generation with elevated wetness and high ethane concentrations, indicating an association with condensates derived from the thermal cracking of liquid hydrocarbons. The absence of isotopic alteration suggests efficient migration and preservation. Basin modeling shows that hydrocarbon generation in the Abu El Gharadig basin began in the Early Cretaceous, with major oil-to-gas conversion occurring much later, and structural traps forming beforehand to secure these accumulations. Collectively, the results confirm a dynamic and effective petroleum system within the Abu El Gharadig Basin, with the Abu Roash and Khatatba formations as key hydrocarbon sources driving both generation and expulsion processes. Collectively, the results confirm a dynamic and effective petroleum system within the Abu El Gharadig Basin, where the Abu Roash and Khatatba formations as key hydrocarbon sources driving both generation and expulsion processes.

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埃及Abu El Gharadig盆地JDT油田热成油气系统的地球化学证据

通过岩石样品和天然气资料的综合地球化学评价，对Abu El Gharadig盆地的含油气系统进行了评价。以上白垩统Abu Roash （C -G）段和中侏罗统Khatatba组为主要烃源岩。总有机碳（TOC）和岩石热解分析显示有机质丰度显著，TOC值高达3.14 wt%，氢指数（HI）峰值为489 mg HC/g TOC，为ⅱ型干酪根。这表明该区具有强大的生烃潜力。热成熟度参数Tmax（430 ~ 448℃）和镜质组反射率（Ro = 0.50 ~ 0.92%）证实这些烃源岩位于油窗内，层段越深，成熟度越接近峰值。来自Apollonia储层的天然气地球化学特征进一步支持了这一解释。这些气体是与产油有关的气体，具有较高的湿度和较高的乙烷浓度，表明与液态烃热裂解产生的凝析油有关。同位素变化的缺失表明了有效的迁移和保存。盆地模拟表明，Abu El Gharadig盆地的生烃始于早白垩世，主要的油气转化发生在晚得多的时间，构造圈闭的形成提前确保了这些聚集。总的来说，研究结果证实了Abu El Gharadig盆地内存在一个动态而有效的石油系统，Abu Roash和Khatatba组是驱动生排过程的关键烃源。总的来说，这些结果证实了Abu El Gharadig盆地内存在一个动态和有效的石油系统，其中Abu Roash和Khatatba组是驱动生排过程的关键烃源。

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来源期刊

Journal of African Earth Sciences 地学-地球科学综合

CiteScore

4.70

自引率

4.30%

发文量

240

审稿时长

12 months

期刊介绍： The Journal of African Earth Sciences sees itself as the prime geological journal for all aspects of the Earth Sciences about the African plate. Papers dealing with peripheral areas are welcome if they demonstrate a tight link with Africa. The Journal publishes high quality, peer-reviewed scientific papers. It is devoted primarily to research papers but short communications relating to new developments of broad interest, reviews and book reviews will also be considered. Papers must have international appeal and should present work of more regional than local significance and dealing with well identified and justified scientific questions. Specialised technical papers, analytical or exploration reports must be avoided. Papers on applied geology should preferably be linked to such core disciplines and must be addressed to a more general geoscientific audience.