Petrophysical assessment of reservoir quality and recoverable reserves in fluviodeltaic Nubian sandstone Saqqara field Gulf of Suez Egypt

Heterogeneous reservoirs require integrated petrophysical rigor to improve the accuracy of hydrocarbon reserve calculation, minimize uncertainty in reservoir characterization, and optimize development options. Using the Fluvio-Deltaic Nubian Sandstone in the Saqqara Field, Gulf of Suez, as an example, this study uses multi-petrophysical workflows, such as well-log correlation, core-log calibration, petrophysical evaluation, petrophysical distribution maps, and multi-petrophysical cross-plot for lithology, fluid saturation, and reservoir parameters, across four important wells (GS323-1, GS323-2 A, GS323-3, and GS323-4 A). Original hydrocarbons in place (OHIP) and recoverable reserves were calculated using volumetric methods, and thermal maturity was evaluated using geothermal gradient estimations. Lithological interpretation, based on neutron-density cross-plots, confirms the dominance of clean sandstone with minimal clay and anhydrite cementation. Thermal analysis indicates a moderate geothermal gradient (~ 2.75 °C/100 m) and formation temperature (~ 147 °C), supporting hydrocarbon maturation. The reservoir exhibits excellent quality, with low shale volume (~ 0.6%), total porosity averaging 13.5%, and high hydrocarbon saturation (~ 78.5%). Despite variations in permeability, significant net pay zones (ranging from 108.5 to 481.5 ft) offer robust development potential. Using volumetric methods, the estimated hydrocarbons in place reach ~ 106 billion barrels, with ~ 31 × 10 ⁹ barrels considered recoverable. These findings highlight the strategic value of the Nubian Formation in hydrocarbon planning and underline the critical role of integrated petrophysical analysis in maximizing production efficiency in mature basins. Moreover, the insights derived from this study can be effectively applied to similar sandstone reservoirs worldwide, contributing to improved resource management and energy security.