Lithofacies characterization and source rock assessment of the lower-middle Miocene Successions in the northern part of Ramadan oil field, central Gulf of Suez, Egypt

Abstract

Facies of rifting basins reflect different depositional environments from deep to shallow conditions. The present study focuses on subsurface facies characterization and source rock assessment of Kareem and Rudeis rocks in six wells lying in the central Gulf of Suez. The distribution of the lithologic patterns delineated through several constructed facies maps. Porosity cross-plots of Kareem and Rudeis formations to determine the rock minerals and porosity attitudes. Rock–Eval pyrolysis was applied to determine the kerogen type, organic matter richness, percentage, and maturation of the source rocks. The greater depth of the two formations was reflected in the western parts while their stratigraphic thickness increases toward the east and the north directions, with decreasing thickness towards the west direction due to an underlain basin structure of the pre-Miocene. Isolith maps show three deep marine lithologies for the two formations with the anhydrite as a fourth shallow marine lithology in the Kareem Formation only. These lithofacies reflect the turnover from the deep to the shallow depositional environment. The facies change from a main shaly limestone in the Rudeis Formation to calcareous shale in the Kareem formation, indicating transmutation from the lower Miocene deep to the middle Miocene shallow marine environments. The cross-plots reflected the existence of limestone, shale, and anhydrite. Geochemically, both formations are marginally good source rock with a marginally good generation of mixed type II/III and type III. Accordingly, Rudeis and Kareem formations could be good reservoirs rather than being potential source rocks in the central Gulf of Suez.