Publications

Banggai-Sula Foreland Basin in Matindok Block is the product of Late Miocene to Early Pliocene collision between Banggai-Sula microcontinent and East Sulawesi Ophiolite (ESO) magmatic arc of Sundaland. Celebes Molasse was deposited eastward into basin area in Plio-Pleistocene as post collision sediment. The thickness of Celebes Molasse, based mudlog from several wells in onshore area, varies from 1500 m to 2700 m and comprises conglomeratic sandstone, sandstone, and shale as flysch deposit. A recent condition, Celebes Molasse sediments have steep dip eastward up to 5° – 20° and onlap to Miocene platform carbonate below it due to exhumation process in post collision stage. In order to image the main reservoir Miocene platform carbonate properly, we first have to model the seismic velocity of Celebes Molasse. Comparison between PSTM (post stack time migration), using RMS (root mean square) Velocity, and PSDM (post stack depth migration), using interval velocity, on NW-SE 2D Seismic Line were made and showed significantly different results. RMS Velocity can’t solve significant lateral velocity changes caused by Celebes Molasse high dip sedimentation and significantly affected the Miocene platform carbonate image on PSTM. On the other hand, interval velocity functions handled the lateral velocity problems very well. Miocene platform carbonate was imaged updip westward on PSTM Section but PSDM Section images the Miocene platform carbonate relatively downdip westward. PSDM Section also imaged a new carbonate build-up on top of Miocene platform carbonate, which can become a new drillable prospect. Finally, Interval Velocity Modeling is a must in this area in order to get the proper subsurface imaging.