Integrated Characterization for Development of the Northeast Betara Field, South Sumatra Basin, Indonesia
Suta I Nyoman, Utomo Budi Tyas, Roger M. Slatt, 2006. "Integrated Characterization for Development of the Northeast Betara Field, South Sumatra Basin, Indonesia", Reservoir Characterization: Integrating Technology and Business Practices, Roger M. Slatt, Norman c. Rosen, Michael Bowman, John Castagna, Timothy Good, Robert Loucks, Rebecca Latimer, Mark Scheihing, Hu Smith
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Northeast Betara Field, located in the south Sumatra basin of Indonesia, is a fault-bounded reservoir comprised of the Oligocene lower Talang Akar Formation. The reservoir consists of two fluvial facies, a lower braided river facies and an upper meandering river facies. Both facies are separated by areally extensive floodplain/marine shale. Based upon both sequence stratigraphic and structural analysis of 3D seismic and well/core data, the distribution of braided river facies is controlled strongly by block faulting coupled with a significant drop in relative sea level. During subsequent early rise in relative sea level, reservoir sands have been re-cycled and reworked to provide better reservoir quality of the upper meandering river sandstones. This facies has tested >1400 BOPD, >10 MCFGPD, and some condensate from NEB #7 well.
The Northeast Betara Field is highly compartmentalized both structurally (faults and folds) and stratigraphically (discontinuous sandstones and shale interbeds). The field consists of separate oil and gas-condensate reservoir systems. Volumetric reserves calculation, combined with material balance studies, indicate the potential oil reserves comprise approximately 10 to 15% of the total potential gas-condensate reserves.
Recognition of reservoir compartments having varying fluid contacts constitutes an important interwell frontier for development of Northeast Betara and other, similar fields in the area. Compartments have been identified using the integrated methodology described here. In structurally and stratigraphically compartmentalized reservoirs such as Northeast Betara Field, development of an integrated 3D geologic model, numerical reservoir simulation model, and production strategy has been critical to optimize both oil and gas production. Oil rim reserves have been produced in the early stage of development, followed by current production from the main gas-condensate reservoir.