Petrographic, palynological, and source rock evaluation of Nubia Sandstone: A comparative study of the October and July Oil Fields, Gulf of Suez, Egypt

Abstract

The Nubia Sandstone sediments in the Gulf of Suez, Egypt, represent significant hydrocarbon reservoirs. However, further investigation is necessary better to understand their source rock characteristics and depositional environments. These sediments lack precise chronological data and have limited palynological information, both crucial for compelling petroleum exploration. This research uses an integrated approach that combines palynology, palynofacies analysis, and petrographic methods to clarify the characteristics of the Nubia Sandstone. Two main facies are identified: the older facies in the July Field, which corresponds to the lower interval of the Nubia B Member and dates to the late Devonian, characterized by conodonts and plant fragments. In contrast, the younger facies found in the October Field and are believed to originate from the Permian-Triassic period exhibit foraminifera-rich strata and a transition from monosaccate pollen grains to Classopollis pollen grains. The results suggest that the Nubia Sandstone exhibits a range of transitional maturity to overmaturity, with the Nubia Sandstone B Member showing significant potential for hydrocarbon generation and predominantly comprising type II kerogen. The samples from the October Field show deposition in a suboxic to anoxic basin, while those from the July Field suggest a proximal oxic shelf environment. This study provides the first source rock characterization which could increase research and exploration for hydrocarbons in different areas in the Gulf of Suez containing the Nubia Sandstone.