Geological Aspect and Hydrocarbon Potential in West Timor

Abstract

Geological condition of the West Timor is originated from the Australian Continent Terrane, Banda Arc Terrane and local deposited rocks. The geology of the study area specifically is divided into Banda Terrane units, Australian Passive Margin Sequence, Gondwana Sequence, Post-Orogenic Sequence, Syn-Orogenic Sequences and Bobonaro Clay Complex. This study aims to analyze the geology and hydrocarbon potential includes the source rock, reservoir rock and seal rock in the West Timor area. The Oligocene-Miocene Mutis Complex beginning the collision between the Asian Continent and the Australian Continent. In this study, it was shown that the highest collision activity occurred at the end of the Miocene - Early Pliocene and continued to recent. Outcrop samples were collected and GC-MS analyses performed in the laboratory for source rocks. The result shows that the main source rocks found was shale of the Aitutu Formation (Triassic) and shale from the Wailuli Formation (Early Jurassic) with Ro>0.7, they are indicating mature souce rocks. The source rocks are thought to be generated in a shallow marine environment and low energy condition with a mixture of terrestrial material. Halobia fossil was found out on the outcrop, which is play as marker fossil of the Triassic age. A reservoir rock is the sandstone from Oebaat Formation. Oebaat Formation consists of interbedded grainstone-wackestone. Belemnite fossil was found on the outcrops, which is marker as a fossil from Jurassic age. The secondary reservoir is a limestone of the Nakfunu Formation (Lower Cretaceous). The reservoir is thought to be generated in a high-density turbidity condition in shallow marine environment. Shale from Wailuli Formation (Early Jurassic) can be a potential seal rock.