Petroleum generation modelling of the Middle‐Late Cretaceous sediments in the Abu Gharadig Field, Northwestern Desert, Egypt

Abstract

The present work introduces an integral study concerning the Middle‐Late Cretaceous source rocks in Abu Gharadig (AG) Field utilizing source rock evaluation techniques and hydrocarbon generation modelling. The used methods include TOC%, Rock‐Eval pyrolysis, vitrinite reflectance (Ro%), and 1D basin modelling data. Our results show that most of the studied marine Middle‐Late Cretaceous intervals in AG Field are considerable as source rocks, excluding the Abu Roash A‐D members. The Kharita, Bahariya, and Abu Roash E & G intervals have mainly gas‐prone kerogen. The Abu Roash F and Khoman B members contain mixed kerogen type II/III with oil/gas‐prone generative potential. Khoman A member has marine type II kerogen with mainly oil‐ and minor gas‐prone generative potential. Among the Middle‐Late Cretaceous rock units, the Khoman Formation is either immature or early mature, whereas others are mature enough to generate hydrocarbons. The burial history models typify a high subsidence rate during the deposition of Kharita, Bahariya, and Abu Roash formations in response to the Tethyan rifting phase. The timing of the peak of oil generation window for the Abu Roash G interval is ranged as Late Oligocene‐Early Pliocene time. Moreover, the timing of the peak of oil generation for the Abu Roash F interval is ranged as Early Miocene‐Latest Miocene. Based on transformation ratios (TR), the Abu Roash F member demonstrates a limited hydrocarbon expulsion (25% > TR <50), whereas both Abu Roash G and Khoman B members can generate in‐situ hydrocarbon (TR ≤10%). Compiling data along the AG basin from previous works infers that there are spatial and temporal discrepancies in organics composition and thermal maturity of the Middle‐Late Cretaceous intervals. Changes in paleoclimate, eustatic, and basin tectonics can be considered as the primary drivers that triggered such spatiotemporal variation. Integrated approaches are needed to constrain the multi‐geospheric interactions of major Cretaceous anoxic events in the Northwestern Desert of Egypt, and to explore the driving forces on these organics‐accumulating events.