Depositional and diagenetic drivers of a heterogeneous reservoir quality in the Neogene strata of the Red Sea (Egypt)

Petrophysical analyses is the most important, but sophisticated, method for assessing reservoir potential. Herein, we analyzed the Neogene sediments that extend along the Red Sea coast between Wadi Khasheir to Ras Honkorab on South Egypt to evaluate their hydrocarbon potential and to characterize factors behind their evolution. A total of 311 rock samples were collected from 32 measured sections. One hundred and fifty thin sections were made for microfacies analyses. The petrophysical measurements were performed on 185 plug samples representing the different formations. A high porosity was recorded within the conglomerate and greywacke petrofacies of the Miocene Ranga Formation, with an average of 14.5% and have permeability up to 3806 and 3516 mD, respectively. Furthermore, the boundstone microfacies of the Miocene Um Mahara Formation have the highest porosity values with an average of 22.2% and permeability up to 1190 mD. The diagenetic pathways were influenced by the depositional characteristics such as composition in greywacke and feldspathic arenite petrofacies, texture in boundstone microfacies, and the primary porosity as well. The presence of felspars and interparticle pores enhanced the secondary porosity and pore throat size via dissolution. The presence of bitumen as pores-filling material in the Pliocene-Pleistocene sediments reveals their importance as hydrocarbon reservoirs in the subsurface. This tectonic configuration of different sub-basins have controlled the sedimentation and the digenesis processes.