Publications

The fold-thrust-belt (FTB) system in Eastern Indonesia has produced oil and gas fields, including the Oseil field in Seram Island. This system results from contractional deformation and can be linked to subduction or collisional tectonic settings. The Central Range Papua and Papua New Guinea FTB formed due to Indo-Australian and Pacific plates' collision during the Late Miocene. While hydrocarbons have been discovered and produced from FTB in Papua New Guinea since the early nineties, no fields have been produced from FTB in Indonesia, except for oil and gas discoveries in the Warim block near the border.

The Lengguru FTB is the western extension of the Central Range FTB, located east of the Bintuni basin. However, no significant exploration has been conducted in this belt. A recent study using integrated remote sensing and a regional gravity anomaly, supported by fieldwork, sandbox modeling, and palinspastic reconstructions, revealed new possibilities for exploring this belt further. The Lengguru FTB is characterized by NW-SE trend km-scale folds with subsidiary thrust faults. The fold's orientation changes to N-S in the northern part because of strike-slip faulting. The folding involves Mesozoic and Cenozoic sequences with an average length of 30 km and width of 5-10 km. Based on the structural geology cross-section, the Lengguru FTB is interpreted as basement-involved deformation supported by gravity interpretation. Fieldwork interpretation reveals the Middle to Late Jurassic sandstone of the Woniwogi Formation as the reservoir and Early Jurassic Kopai Formation as the primary source rocks in this area. Palinspastic reconstructions and sandbox modeling suggest the FTB has been experiencing more than 30% shortening. This evidence is critical concerning hydrocarbon maturity and preservation in this FTB. Numerous oil and gas seeps were discovered during fieldwork to the western margin of this FTB. Further work needs to be done to ramification prospect of the Lengguru FTB.