Stratigraphic Barriers in a Cretaceous Tide‐Dominated Estuary: Integrated Multiscale Analysis of Dry Well Causes, Wadi Rayan Oil Field (Afro–Arabian Shield Margin, Egypt)

Abstract

ABSTRACT The Wadi Rayan oil field has experienced inconsistent production. This stems from lateral and vertical heterogeneities within the sandstone reservoirs, which profoundly impact hydrocarbon flow. A comprehensive multiscale study integrating sequence stratigraphy, seismic interpretation, and petrographic analysis was conducted to characterise the reservoir system. Our results reveal a complex, tidally‐dominated estuarine system deposited during the Cenomanian on a low‐gradient shelf. Crucially, reservoir quality is facies‐controlled, with high‐energy channel sands preserving good porosity (0.15–0.28) despite silica cementation, whereas moderate‐energy tidal bars suffer significant porosity reduction from calcite cementation. Structurally, the main field closure is a NE‐asymmetrical anticline bounded by faults. We constructed a 3D static model using detailed facies and property distributions, estimating cumulative stock tank original oil in place of 16.33 MMSTB across three reservoir intervals. The model definitively identified a critical stratigraphic barrier—composed of low‐permeability shelf shale and carbonate facies—that compartmentalises the reservoir and explains the presence of dry wells (e.g., WR‐2X and WR S‐1X) at structural highs. This finding challenges the notion that structure alone controls entrapment, demonstrating instead that stratigraphic complexity can override the structural template. We consequently propose drilling two appraisal wells to further evaluate future planning. This integrated approach conclusively links dry wells to specific stratigraphic complexities, enhancing reservoir understanding and providing a predictive framework for improving recovery in similar geological settings.