* Institute of Technology Bandung ** FERG Geosains Indonesia *** Pertamina Hulu Energi IPA16-294-G PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION Fortieth Annual Convention & Exhibition, May 2016 EXPLANATION OF SERAM ISLAND’S MORE PROLIFIC OIL POTENTIAL COMPARED TO ITS OFFSHORE AREA USING PALINSPASTIC AND BASIN MODELING APPROACHES Qi Adlan* Sony M. Kartanegara** Asep H. P. Kesumajana* Edin A. Syaripudin*** ABSTRACT Seram Island is located offshore West Papua, Eastern Indonesia. This tectonically complicated area is host of several oil fields such as Oseil and Bula. These oil fields lie on the Seram Fold-Thrust Belt (SFTB) which extends southeastward along the Banda Arc. Oil occurrences in this island are controlled by their position within tectonics related to the SFTB evolution. However, the SFTB extension to the offshore area is considered unattractive in terms of hydrocarbon potential compared to the island. This study focuses on petroleum system investigation in the offshore area, including the presence and the position of the source rock relative to the SFTB deformation. Retro-deformable palinspastic restoration was used to reconstruct the source rock history, combined with geochemical analyses and basin modeling. The geological features recognized on NE-SW seismic are foreland basin features. The source rock analysis showed the Jurassic interval is the primary source rock of the area (Adlan et al., 2016; Bradshaw et al., 1994; Price et al., 1987). The result showed that the Jurassic source rock reached oil maturation window in 33 Ma. Compressional tectonic event in late Neogene caused emergence of the imbrication block sequentially from west to east. This imbricated block emergence increased burial of the source rock in front of it basinward; thus the source rock in the frontal area reached the 1.3–2% Ro gas window before start of imbrication. Gas migration most likely displaced the existing oil from traps in the imbrication block. As a result source rock gradually changing in SFTB, onshore Seram Island is more oil prolific than the offshore area. INTRODUCTION Major tectonic features, Seram Fold-Thrust Belt (SFTB) and Seram Trough, stretch from Seram Island to offshore West Papua. These structural features, especially the trough, extend from south to north along Outer Banda Arc zone and arced open to the west (Charlton, 2001). The outer arc formed as result of collision between Australian continental margin and the Banda Volcanic Arc (Peck and Soulhoul, 1986). This tectonic event created foredeep basin systems at the front of a developing fold-thrust belt in the outer arc (Audley-Charles, 1986; Tandon et al., 2000; Pairault et al., 2003; Hill, 2005; Sapiie et al., 2013).The collision event in Seram Area created repeated Mesozoic–Miocene sequences interpreted as very young zones of thrusting within the Australian continental margin (Pairault et al., 2003). Petroleum system plays in the SFTB Area have been challenging due the structural complexity and poor quality seismic data. The source rocks of the study area expelled hydrocarbons to Seram Island. Primary source rock in this system is Jurassic marine siliciclastic rocks, which were deposited along the rifted margin of Gondwana (Price et al., 1987; Bradshaw et al., 1994). Deepwater drilling of Lengkuas-1 well in Semai Block located in the Seram Trough shows no presence of hydrocarbons. Not far away, oil is produced in Oseil and Bula Fields on Seram Island (Figure 1). The objective of this study is to demonstrate the methodology used in 2D basin modeling, integrated with palinspastic restoration to show how basin modelling can be used to improve understanding of petroleum systems in structurally complex systems while reducing exploration risk and improving exploration success. METHODS This investigation focuses on SFTB part of foreland basin system in the northern Outer Banda Arc. To understand the hydrocarbon potential variation and