Publications

Wiriagar Deep Paleocene is a gas field, forming part of the Tangguh complex in Papua Barat, Eastern Indonesia. The field straddles the northern shoreline of Bintuni Bay,and is defined by 8 exploration and appraisal wells. The field is covered by several 3D seismic surveys. The onshore and transition zone is covered by 1997-vintage 3D data of moderate to poor quality. The offshore part has both 1997-vintage towed streamer and 2010-vintage sparse OBC data, which has good to moderate quality. The Paleocene unit was recently re-interpreted using a dataset with post migration stack reprocessing (PMR) from the onshore and offshore OBC 3D Pre-Stack Depth Migration (PSDM) sets. The PMR included data clean-up via Structurally Conformable Filtering (SCF) implemented in a frequency-dependant and time-variant manner. Individual reservoir sands are difficult to map, but bounding surfaces at Near Top Paleocene and Base of Late Cretaceous were mapped with a fair degree of confidence. Horizons were mapped in the time domain then converted to depth using seismic velocities before calibration to well markers using gridded scale-factors. Due to the limited data quality and lack of direct mapping at target, the structural uncertainty was explored through a conventional drop-out analysis plus a process of integrating different structural scenarios through interpreter guided scaling of the structures and isochores. This suggested up-to 350ft depth uncertainty approximately 5km from well control. A generalized depth uncertainty map was generated with zero uncertainty at well locations, increasing to 350ft depth uncertainty at 5km radius from well influence. Upside and downside depth structure maps were then generated by applying this generalized depth uncertainty map to the reference depth structure map. This was believed to represent the uncertainty in a simple and easy to understand way.