Semai III block is located between Onin Island in the northeast and Seram trough in the southwest, all located in the western part of Papua Island. The Eastern Indonesia (The especially Bird’s head Region) is tectonically and structurally extremely complex. Two major hydrocarbon producing basins were discovered : the Salawati Basin (oil producing) and the Bintuni basin (gas producing). This paper is presenting internal house study results of ongoing study about structural geology framework and its implication to the hydrocarbon exploration in Semai III blok.
Based on the 2D seismic interpretation in the Semai III block generated structure pattern : NW-SE trending anticline and thrust fault as a result from sinistral strike-slip system of the Sorong Fault Zone (SFZ). The SFZ is active and faulting since Late Miocene, and deformation also occurs around the Bird’s Head area. The Misool Onin Kumawa Ridge (MOKR) re-active since the Late Oligocene along with its folding process, then thrust fault developed and continued around the MOKR. The structure reactivation process is also very intensive up to the Jurassic basin area and then created a high area that known as Onin High. The strike-slip system of the SFZ and the MOKR folding and faulting created series of thrust fault in the Semai III block. The anticlines and thrust faults can be potentially as a structural traps in this block.
Based on the 2D seismic composite line from NW-SE from inside to outside the block indicated that the crest of anticline in the Semai III block is higher than the other block as well as the water depth in Semai III is also shallower than the other blocks. On the 2D seismic composite line after flattening at the horizon of the Miocene package indicated that the Semai III block is lower than the surrounding blocks, its explain that all of the Mesozoic to Tertiary sediment that provenance from the Onin High will be deposited in the Semai III block during the uplift and erosion of the MOKR. Therefore, in this block there is a potential reservoir from the sediment accumulation of Onin High.
Authors : Purwanto W. Atmoko, Sukanda Chandrahayat, Rakhmadi Avianto