Multi-disciplinary approach to reservoir characterization and 3D static modeling of the Paleozoic to Middle Jurassic Sequence in the Obaiyed Field, Shushan Basin, Egypt

Abstract

The Obaiyed Field, located in Egypt's Shushan Basin, is a geologically complex tight gas reservoir. Despite its substantial gas reserves, production remains restricted, leading to the suspension of several wells. This study integrates geological and petrophysical datasets, including core descriptions, imaging logs, conventional well logs, and seismic data, to develop detailed structural, facies, petrophysical, and hydraulic flow models. In the uncored zones, permeability was estimated using artificial neural networks calibrated with core data. Structural modeling identified a network of NW–SE and NNE–SSW trending normal faults, adding to the field's structural complexity. The Lower Safa Member shows better reservoir potential and comprises approximately 93.8 % sandstone deposited in a deltaic environment with tidal and fluvial influence. In contrast, the Shifah Formation contains only 22.45 % sandstone, with a higher proportion of shale and siltstone, indicating deposition in a deeper marine environment. Petrophysical analysis of the Lower Safa Member indicates that its reservoir quality decreases toward the north. The study of Hydraulic Flow Units (HFUs) identified five distinct units, with HFU5 (predominant in the Lower Safa Member) having the best reservoir quality, while HFUs 2–3 (common in the Shifah Formation) have much lower flow potential. These findings offer crucial guidance for the exploration and development of tight clastic reservoirs in the Northwestern Desert basins of Egypt and may also be relevant to similar analogues in North Africa.