Exploitation of thin oil zones overlying thick, productive carbonate formations poses a unique challenge for reservoir development, particularly with strong water drive. The main challenge is effective oil recovery without excessive water production. Reservoir management considerations addressed in this study include locating current fluid contacts, evaluating geological complexity, assessing vertical permeability contrast, optimizing well configuration (length and vertical placement), utilizing appropriate geo-steering techniques to ensure correct well placement, and optimizing completion design. This paper compares comprehensive reservoir simulation findings with field results for various well configurations for a carbonate reservoir in Saudi Arabia. Preferred wellbore configurations have large reservoir contact with laterals placed at the top of the thin oil zone and wells completed to provide uniform flow contribution along the wellbore. Best practices have been developed for effective oil drainage from thin oil zones overlying thick, permeable carbonate formations under strong water drive.

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