Integrated 3D static modeling approach for evaluating the Cenomanian Bahariya reservoir in Falak Field Shushan Basin northwestern desert Egypt

Abstract

This study integrates petrophysical analysis, seismic interpretation, and 3D reservoir modeling to evaluate the hydrocarbon potential of the Albian-Cenomanian Bahariya Fm in the Falak Field. Seismic interpretation reveals a structurally compartmentalized field dominated by a NW-SE trending normal fault system, compartmentalizing the field into distinct up-thrown and down-thrown blocks. Time-to-depth conversion, validated by synthetic seismogram, check shot data that is used to build a velocity model, facilitated the construction of structural contour maps, identifying two primary three-way dip closure prospects. The Bahariya Fm exhibits significant thickness variation (568 ft to 861 ft), with net pay zones ranging from 47 ft to 197.5 ft. The average effective porosity is between 16.3% and 22.7%, while the average oil saturation is between 44.2% and 51.4%. Petrophysical evaluation based on well logs, cross-plots, well-to-well correlation and facies modeling (55.48% sandstone) indicates that sandstone represents the dominant modelled facies, followed by siltstone, shale, and minor carbonate/limestone facies. The sandstone-rich intervals are mainly associated with the lower Bahariya units and represent the most favorable reservoir zones. A 3D geocellular model, incorporating interpreted horizons, faults, facies distributions, and petrophysical properties (populated via Sequential Gaussian Simulation), visualizes the reservoir architecture, confirms superior reservoir quality (higher Øeff, lower Sw/Vsh) within the central, northwestern, and southeastern areas, particularly in the lower fluvial sandstone units. These results prioritize the northern and southeastern structural closures for future development drilling targeting the Bahariya Fm due to optimal reservoir properties and hydrocarbon pore volumes. Model uncertainty is mainly related to sparse and uneven well control, facies distribution away from wells, log upscaling, and variogram-based property modelling. Volumetric calculations estimate the total OIIP/STOIIP of the Bahariya reservoir at approximately 160 MMSTB, with Bahariya-I contributing about 46 MMSTB and Bahariya-III contributing about 114 MMSTB. The workflow is extendable to analogue subsurface clastic reservoirs in the Northwestern Desert and North Africa.