Late Cretaceous Matulla sandstones in the Gulf of Suez Basin: geophysical assessment of pre-rift oil reservoirs

Abstract

This research project aims to conduct a comprehensive geophysical evaluation of the oil potential within the pre-rift Matulla Formation in the Rabeh and Edfu-Saqara fields, situated in the Gulf of Suez Basin. The investigation relies on the analysis of wireline logs from twelve wells, with eight drilled in Rabeh field (Nageh-1, South Malak-1, Tawoos-1, RE-8, RE-22, RE-25, RE-2 & RE-4) in the onshore south-western Gulf of Suez Basin, and four wells (GS323-1 A, GS323-4 A, Edfu A-3 & Edfu A-5 A) drilled in Edfu-Saqara field in the offshore central Gulf of Suez Basin. Additionally, the interpretation of twenty seismic sections covering the Rabeh field reveals the prevalence of NW–SE normal faults, supplemented by minor E–W faults. These faults play a crucial role in creating structural traps conducive to retaining oil and gas. The analysis of well logging data indicates encouraging petrophysical indicators for the Matulla sandstones, suggesting their potential as reservoirs in the studied fields. These reservoirs exhibit a moderate net pay thickness ranging from 25 to 400 feet, a fair to good net/gross ratio between 0.07 and 0.68, low shale content ranging from 0.03 to 0.20, excellent effective porosity ranging from 0.10 to 0.20, minimal water saturation ranging from 0.10 to 0.35, and high hydrocarbon saturation ranging from 0.65 to 0.90. The obtained results revealed that the Matulla Formation is being considered as a prospective hydrocarbon reservoir in addition to the widely recognized Nubia sandstones and Miocene reservoirs in both Rabeh field and Edfu-Saqara field. Moreover, the constructed iso-parametric maps for the calculated petrophysical parameters in the Rabeh field recommend a strategic focus on the eastern side of the Rabeh field for potential drilling locations, given the presence of high-quality Matulla sandstone reservoirs in that area.