The Unayzah formation is a nonmarine siliciclastic unit. It consists of massive quartzose sand to argillaceous sandstone, silty sandstone, siltstone, mudstone, and minor carbonaceous shale. The Unayzah is typically 300-350 ft thick at Awali. The Unayzah consists primarily of braided stream and related floodplain deposits. The depositional model includes flood plain deposits, meandering channels, point bars and alluvial fans. Six Lithostratigraphic units were identified based on the log character in the Unayzah sequence. These units are named as U1, U2, U3, U4, U5 and U6 from top to bottom. Impedance contrasts at the top Unayzah gas reservoir are strong enough to generate a negative reflection at the interface and the resultant amplitude can be directly related to reservoir porosity. This was confirmed by evaluating 1-D forward modeling (synthetic seismogram) results from several wells in the study area. The reflection response was validated in 3-D seismic data by a sharp negative reflection at the top of Unayzah reservoir with good correspondence between reflection intensity and reservoir quality as observed at well penetrations. This study is to test the above mentioned method in the flanks of Awali structure outside the known production area.


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