Publications

Middle Jurassic Sub Thrust: The Under-Explored Oil Play in The Offshore West Timor, Nusa Tenggara Timur, Indonesia

Proceedings Title : Proc. Indon. Petrol. Assoc., 47th Ann. Conv., 2023

West Timor is located along the Banda-arc’s collisional trend but has been relatively less explored in comparison to the other hydrocarbon provinces associated with the Banda-arc, such as Buton, Seram, and Timor Leste. Five exploration wells were drilled in the West Timor province targeting three of four anticipated exploration plays. Play 1 is a Middle Jurassic sub-thrust play situated in the front-most traps and facing the matured hydrocarbon kitchens of Bena and Kolbano Deeps; it was solely tested by the Banli-1 well. Play 2 is a Middle Jurassic horst-structural play situated offshore the northwest shelf of Australia, and was tested by the Napoleon-1, Manta-1, Belalang-1 and Mina-1 wells. Play 3 is the Intra Triassic-to-Permian carbonate and clastic play over the NW shelf of Australia that is fully penetrated by the Napoleon-1 and Kelp Deep-1 wells. Play 4 is Neogene orogeny play along the southern coast of West Timor. Post-drill analysis of the Play 2 targets suggest that migration has been the main problem. There are Triassic Aitutu’s type II oil-prone and Triassic Babulu’s type II/III gas-prone source rocks along the Kekneno and Niki-Niki outcrops. Despite good gas readings and oil shows with cut fluorescence in the Jurassic section, the failure of the Banli-1 well may be due to its off-structure position based on the gravity model. We conducted 1D basin modeling on the Triassic source rocks and found that oil dominates most of the hydrocarbon generated from the Bena and Kolbano Deeps. The exploration of Play 1 is highly recommended for prospectivity and is the focus in this study as it remains an under-explored oil play. It could potentially be combined with Play 4 as the secondary target. The exploration Play 3 requires further thorough evaluation regarding the over-matured Permian source rock and highly compacted Middle Triassic sandstone and Permian carbonate. Three (of nine) structural leads were identified immediately in front of the Bena and Kolbano Deeps and consist of unrisked 4.7 Bbo in-place mean resources. These leads are located in moderate water depth and close to the shoreline making them attractive targets for fast track development.

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