Hydrocarbon Source Rock Potential in The Timor Gap Zone of Cooperation and Surrounding Area



A part of the Timor sea between Indonesia and Australia which appears to have good hydrocarbon potential is known as “The Timor Gap Zone of Cooperation”. Exploration activity in this area, such as seismic acquisition and drilling, has been more frequent recently. The objective of this paper is to give a contribution to the hydrocarbon exploration through evaluation of the source rock potential such as hydrocarbon generation, migration as well as trapping mechanism and its implication to the hydrocarbon accumulation within the study area. Hydrocarbon source rock analysis through a number of wells indicated that the Early Jurassic to Early Cretaceous Plover Formation and Flamingo Group are considered to be a major source for genera-tion and expulsion of hydrocarbon in the study area. The Plover Formation is composed of fluvio-deltaic with variable amounts of shales and minor coal. These sediments contain high organic matter assemblages. The Hydrogen Index data suggest that the formation is principally oil prone with some indications of being gas prone. The Flamingo group consists predominantly of shales (Swan Formation in the Vulcan Sub-Basin and Frigate shale over the Sahul platform). Both sequences contain good source sediments which appear to have both oil and gas generative potential. The peak of oil generation (Average GG. = 3 – 5 deg.C/100 m and Vr (%Ro) = 0.60 – 1.3) is located between approximatelly 2,000 m and 6,000 m. The source sequences within the intraformational shales of the Plover Formation are fully mature in the Malita Graben whereas the Flamingo Group is only in the early mature stage to have generated hydrocarbon in the Sahul Syncline and the Vulcan Sub-Basin and is overmature within the Malita Graben. Those areas are identified as potential major kitchens for providing hydrocarbon which may occur in the study area. •


Authors : Eddy Sjahbuddin & Basuki Puspoputro