Variability of Paleogene Source Facies of Circum- and Drifted Sundaland Basins, Western Indonesia: Constraints from Oil Biomarkers and Carbon-13 Isotopes

Satyana, Awang H.¹; Purwaningsih, Margaretha²
¹BPMIGAS, Jakarta, Indonesia.
²ConocoPhillips Indonesia, Jakarta, Indonesia.

The Tertiary basins encircling/circum-Sundaland of Western Indonesia (North Sumatra, Central Sumatra, South Sumatra, Sunda-Asri, West Java, East Java, Barito, Kutei, West Natuna and East Natuna Basins) and its drifted parts (South Makassar Strait, West & South Sulawesi and Bone Basins) were initially formed in the Mid- to Late Eocene mostly related to trans-tensional rifting induced by regional post-collision escape tectonics of India-Eurasia collision and/or roll-back movement resulting in back-arc opening due to slower rate of coeval subduction. Thick intervals of Paleogene sediments were deposited in infra-rift, main rift, late stage-rift and early stage post-rift/sag phases of the basins, covering the depositional environments range from nonmarine, lacustrine, fluvio-deltaic, paralic, and marginal- to fully marine facies.

The syn-rift, late stage-rift and early stage post-rift/sag sediments are the most important hydrocarbon source rocks in the region. These rifts and their overlying early stage post-rift/sag formed active kitchens in the basins. These kitchens are almost always devoid of exploration wells causing precise interpretation of the source facies is impossible due to the absence of samples for biostratigraphic analyses. However, characteristics of the depositional environments and nature of the source rocks deposited within the kitchens can be assessed from a detailed examination of biomarkers and carbon isotopes of oils generated. On this basis, interpretation of variation of the Paleogene source facies of circum- and drifted Sundaland basins is presented.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012