Characteristics and generation modeling of some source rocks in the South Eastern offshore Mediterranean area, Egypt

摘要

The offshore North Sinai area contains attractive approaches to be investigated by means of hydrocarbon potential. The present work aims at evaluating three source rock units; the Upper Jurassic, the Lower Cretaceous, and the Upper Oligocene that have a varying lithology including limestones, marl, and shales. The evaluation is based on results of TOC, Rock-Eval pyrolysis, and vitrinite reflectance analyses for ditch cuttings from 5 wells. Besides, constructing 1D basin models for several wells took place in the present study to estimate the generation timing. The geochemical results show that the Upper Jurassic contains poor to good organic quantity with poor to good hydrocarbon generating potential of type II/III and type III kerogen. The Lower Cretaceous rocks are poor to very good in terms of organic richness and hydrocarbon generating potential as well and belong to type II/III and minor type III kerogen. Moreover, a poor to good richness was encountered for the Upper Oligocene, with poor to fair hydrocarbon generation potential of kerogen type III. 1D basin modeling results indicate that three main tectonic phases influenced the burial history comprising the Jurassic-Cretaceous rift, the Late Cretaceous-Oligocene uplift associated with the Syrian arc folding, and the Late Miocene rift. These movements affected the thermal maturity in the studied area. The Upper Oligocene source rock is immature to early mature in most of the studied wells, whereas the Lower Cretaceous and Upper Jurassic source rocks were entered the main stage of hydrocarbon generation earlier in the eastern wells than the western wells, related to a variant tectonic impact in the area. The top oil window was reached at depth ranges from 2300 m in Mango-3 well to 4000 m in Hout-1 well, while the base of the oil window is found only in Mango-1 well at 4300 m depth.