Petroleum systems and hydrocarbon prospectivity of the offshore Garad Basin, north-central Somalia

The petroleum potential of the offshore Garad Basin in north-central Somalia remains poorly constrained. This study provides an integrated reassessment of the basin’s structural framework and petroleum system using 2D seismic reflection and well data, and 1D/2D basin modeling. Seismic interpretation reveals coast-parallel culminations, tilted fault blocks, and rollover structures at shelf-to-upper slope depths, with several closures identified within the Upper Cretaceous interval. The Upper Jurassic Uarandab marine mudstone is identified as the main source rock in the offshore Garad Basin, with an average thickness of approximately 95 m. Basin modeling results, calibrated to vitrinite reflectance data, indicate that the Uarandab source rock entered the oil window during the Oligocene and reached the main oil window by the Middle–Late Miocene beneath the shelf and upper slope. Transformation ratios increase basinward and approach expulsion thresholds in depocenters during the interval of Oligocene–Miocene trap formation. The Upper Cretaceous Gira rudist-shoal carbonates constitute the main reservoir targets, with dolomitized Hamanlei stringers representing secondary prospects. Key exploration risks include pre-Aptian truncation of the Uarandab source, trap breach during Oligocene–Miocene reactivation, and depth conversion uncertainty. Future work should include long-offset 2D/3D seismic acquisition, checkshot/VSP data, and geochemical calibration to better constrain source kitchens and structural closures.