Publications

The Jatiluhur Block is located in the southern portion of the West Java Basin and covers Bogor Trough and volcanic centers on the South. The Block is highly prospective but under explored. Perhaps, in the past it was considered as a difficult area to explore, where seismic acquisition was hampered by volcanic cover and rugged topography associated with complicated structures. One of the targets for reservoir in the area is the Batu Raja Limestone. Typically, Batu Raja reservoir quality is best in the reefal buildup facies. The most favorable environment for reefs to develop is on basement highs. If this condition occurs at the perimeter of half graben structures, which are common in the Jatiluhur Block, it is ideal for hydrocarbon sourcing and trapping. However, these locations generally have poor seismic imaging due to lateral velocity variation in the overburden. In addition, in the Jatiluhur Block, complicated thrusting also adds lateral velocity variation.On the northern part of the Block limited seismic data of late 80s and early 90s vintages are available, and have been reprocessed in 1998. However, in these structurally complex areas conventional seismic processing does not provide optimal imaging. Standard velocity analysis is too crude for the purpose and the assumption of hyperbolic moveout does not always apply. Recently, we have successfully utilized pre-stack depth migration (PSDM) to improve imaging. PSDM processing uses advanced velocity analyses techniques including tomography that rely on geologic model, depth focusing and velocity scans. Modeling is done iteratively to arrive at a final velocity model, which is then used to build a final depth section. Results of the PSDM have enhanced the imaging of our prospects, in particular one of our Batu Raja buildups. It is probably a reef structure, resting on a basement high with younger sediments onlapping onto the structure. In addition to clearer definition of fault traces and sedimentary structures, PSDM has better defined the depth, positions and dips of the onlapping layers suspected as potential thief zones on time sections, which are important in our prospect evaluation.