Back to Basics: How a Field in Offshore Sarawak Optimize Production and Maximize Recovery Via Analytical Approach

Abstract

Field XX is a mature field located in offshore Sarawak with relatively low RF due to reservoir complexity and compartmentalization. Previous development campaigns focused on specific compartments, while future development plans are targeting less developed compartments to increase the field-wide recovery. This paper is intended to discuss the methods and the success story of production optimization and recovery maximization effort from developed reservoirs: Classical Method: Data and analysis integration allows identification of unswept oil and behind casing opportunities (BCO). The approach begins with incorporating reservoir maps and correlations with current fluid contacts (from reservoir performance and logging data), pressure trending, production bubble maps etc. Identified opportunities are further evaluated using MBAL and Prosper models to de-risk the potential.Dumpflooding: From wellbore utilization review and reservoir performance analysis, in situ dumpflood candidates can be identified. In Field XX, most wells are completed in multiple sand sequences, which open up the opportunity to utilize water-producing reservoir to naturally flood the depleted reservoir via pressure difference in shut-in conditions.Drainage Optimization: Over the production life, numerous development wells were drilled and completed targeting specific reservoirs. After decades of production, adjacent wells started to feel the interference of the other, creating a sub-optimal production condition. Via gross rate vs. top node parameter analysis, well drainage optimization opportunity can be achieved by shutting less productive well to allow the better to continue producing at a higher potential. Using analytical reservoir engineering, Field XX managed to achieve the following: (A) identified 2 unswept/attic oil BCO to increase RF in respective reservoir by 2-4%; (B) implemented drainage optimization to increase the technical potential by 40% and delay water table progression by shutting in the downdip neighbouring well; and (C) identified a dumpflood candidate to provide pressure support prior to a more comprehensive water injection project in the future.