f Mapping and re-evaluation of the main Unayzah A Eolian fairway, southeast of Ghawar field, Saudi Arabia

The Lower Permian – Upper Carboniferous aged Unayzah Group constitutes one of the prime targets of Saudi Aramco’s exploration efforts in the Paleozoic section. The upper reservoir interval, Unayzah A, is characterized in the area southeast of the Ghawar field by a predominance of eolian sandstones that constitute the main reservoir. They are relatively continuous within a west-east trending depositional fairway that has been defined by both well and seismic data. Early exploration targeting these reservoirs was centered on structural closures and resulted in the discovery of several large gas fields, like Tinat and Midrikah. The latter was eventually proved to have a large stratigraphic trap component. A re-evaluation of legacy 3D seismic and interpretation of new 3D seismic and well data has led to an increased prospectivity within the Unayzah A reservoir interval. This has helped to refine the mapping of the hydrocarbon potential in the eolian fairway. Stratigraphic plays were identified in an area of about 8000 sq km where no reliable structural closures are present. These plays are based on reservoir quality and the presence of lateral seals as inferred from seismic and well data.