oa Unlocking the Upper Shu’aiba stratigraphic play in northern Oman

Three years ago Petroleum Development Oman (PDO) started unravelling a Shu’aiba stratigraphic play in Oman. The reservoirs are thin prograding units deposited on the margin of the shallow Lower Cretaceous Bab Basin. They are sealed above by thick shale (Nahr Umr Formation) and laterally by intercalated argillaceous carbonates. The best reservoir is found in the subcroping shoaling part of the prograding unit. The reservoir units are generally too thin to be resolved by seismic. However, the clinoform geometries, despite the very gentle dips (1° to 2°), are sometimes visible on seismic mainly highlighted by tuning effects. In 2003-2004 a re-processing effort involving receiver-consistent “Al Burj” decon, a simple and practical high-order move-out method combined with a carefully revised velocity field, improved the data quality significantly and permitted the identification of several new Upper Shu’aiba features. To build a better understanding of the multiples and their generation, we have also been using a new kinematic multiple<br>prediction method. The method has been proven robust as we have successfully predicted multiples that have been clearly identified on seismic and later validated by the wells. The detail of the method will not be covered in this presentation but examples will be given. This relatively simple and practical processing sequence has to a large extent been a key to unlock the Shu’aiba potential for PDO and should be of interest for others facing similar geological challenges. It is on-going work but since this play concept was first successfully proven in the PDO concession in 2003, the newly processed data has had significant impact on the play.