FMI and 2D seismic integration for fractured basement reservoir assessment, Geisum area, Gulf of Suez.

Fractured basement reservoirs represent critical contributors to global hydrocarbon production, with lithologically heterogeneous systems such as weathered granites serving as economically viable targets. In the tectonically active Gulf of Suez rift basin, fractured basement units are increasingly recognized as high-potential reservoirs for hydrocarbon exploration. This study investigates the Geisum Oil Field, a prolific southern Gulf of Suez hydrocarbon province, where basement-hosted production challenges conventional reservoir paradigms. A multidisciplinary approach combining advanced geophysical well logs (including Formation MicroImager [FMI] and resistivity anisotropy analysis) with 2D seismic interpretation was employed to (1) delineate conductive fracture networks, (2) quantify fracture aperture distributions, and (3) resolve structural controls on reservoir heterogeneity. Results identify three dominant fracture orientations-NE-SW, NW-SE, and ENE-WSW-aligned with regional stress regimes. Quantitative analysis reveals a maximum fracture aperture of ~ 0.7 mm within the uppermost basement interval, correlating with enhanced porosity (φ) and permeability (k) zones. Fault intersection geometries were found to amplify fracture density, creating interconnected conduits that optimize reservoir quality. However, kinematic analysis of fault systems highlights potential compartmentalization risks, as insufficient fault seal integrity may permit hydrocarbon migration along reactivated fault planes. These findings underscore the dual role of tectonic fracturing in basement reservoirs: while fracture networks enhance storage and flow capacity, dynamic fault systems necessitate rigorous seal evaluation to mitigate leakage hazards. This work provides a framework for de-risking basement reservoir exploration in rift-related settings globally.