Devonian Sequence consists of Jubah, Jauf and Tawil Formations and overlain unconformably by the clastics of the Permian Unayzah formation. Jubah is the younger formation in Devonian Sequence; its upper part has silicified sandstones, grey to black carbonaceous shales and coal with thin dolomitic shale/sand beds. Lower part has monotonous sequence of very fine to medium grained thick sandstone beds and subordinate grey siltstone, shale interbeds. Jauf formation underlies Jubah and overlies Tawil formation with conformable contacts. After deposition of Tawil, the shallow marine sands of Jauf formation were deposited over a broad shelf. Jauf reservoir is relatively cleanest and most porous of all pre-Unayzah reservoirs. Jauf is the main reservoir tested for gas in Awali field. Tawil is the older formation in Devonian and is mainly of sandstone with Shale intercalations. Depths of Devonian reservoirs of Awali field are in the range of 10,000 ft to 15,000 ft. Individual porous layers are 5-15 ft thick and alternate with tight well-cemented sandstones or shales. Gas shows were also reported in few drilled wells of Awali in Devonian reservoirs, but production testing was not carried out in these wells.

3D Seismic interpretation has been carried out by using 3D Re-processed PSDM volume. Integration of 3D seismic data and Geological information resulted in preparation of detailed subsurface structural and attribute maps at selected levels. Seismic attributes such as Frequency and Amplitude maps show some anomaly on Jubah, Jauf and Tawil levels, these are indirectly indicating the hydrocarbon reservoir development and also validated with the available Well's test results at Jauf level. Few potential stratigraphic and fault closure traps have also been identified in the flank of the Awali field.

The study resulted in identifying potential areas for exploration and supporting the ongoing exploration efforts in surrounding offshore areas for similar gas prospects.

You can access this article if you purchase or spend a download.