Publications

In 2020, Pertamina EP made another gas discovery in Banggai-Sula Basin. However, the prediction missed the top of formation by several hundred meters and therefore increased the uncertainty in the actual amount of the discovered gas resources. The previous geological model was based on 3D Pre-Stack Depth Migrated seismic data from 2018. With only one well as data control, plus complex structure and the proximity to the Batui thrust, the velocity has not been modeled correctly. To reduce the uncertainty, a reprocessed seismic data is required to help building an updated geological model. The newly drilled well, WOL-002, provides new velocity information for PSDM reprocessing. It is however located below an ophiolite layer when signals are very weak. To improve the signal to noise ratio, a powerful yet time-consuming 5D Interpolation is employed. This step significantly improves image quality especially below the thrust. Since this project is tightly time constrained, a careful parameterization has been done for improving processing efficiency. As a result, the imaging can be finished ahead of schedule. Reflector’s depth is confirmed using not only velocity data from well W-20 but also from the neighboring field. New interpretation based on the 2020 reprocessing suggests a larger structure in the subsurface compared to the previous model. This newly processed 3D seismic is also used for identifying new prospect closer toward the thrust zones.