Publications

The Suban field is one of the largest gas fields in South Sumatera producing from fractured pre-Tertiary basement, sandstone and carbonate formations. Throughout the life of the reservoir subsurface data acquisition such as static gradient surveys, pressure build ups and production logging tools have been continuously used to improve reservoir characterization. Originally data acquisition was concentrated on wells in flank areas to address the risk of aquifer influx and in-place uncertainty. As the recovery factor increased, aquifer influx and in-place uncertainties have been significantly reduced, and focus has shifted to reservoir connectivity and individual well performance. The field is starting to reveal more complex internal connectivity than the originally assumed single-tank behavior. Additionally, measurements of well deliverability have been historically limited by well test equipment and facility constraints, resulting in significant uncertainty of the actual shape of individual well inflow performance relationships (IPRs) at lower pressures. Future data collection needs to be designed to address these uncertainties, and the dynamic reservoir model must be adjusted to capture the range of their impact on future performance. This paper will present the recent changes to the data collection and reservoir surveillance program. It will discuss the updated strategy of static pressure collection and testing of well performance. Recently gathered data has been combined with geologic information and used to build a dynamic reservoir model for the Suban field. This model considers uncertainty from reservoir connectivity and well deliverability. We will show the results of a comprehensive performance uncertainty analysis. The outcome of this modeling study helps to improve our understanding of the reservoir, further reduces uncertainty in original gas in place, and characterized the uncertainty in the production forecast for various development scenarios. Furthermore, it helps to refine the newly implemented strategy for future data acquisition in the Suban field.