The Timor Trough: Opportunities and Challenges
By Dr. Nick Hoffman, petroleum geophysicist, 3D-Geo Consultant Group
Presented at the International Energy and Mineral Resources Conference
5 – 7 March 2003, Dili, Timor Leste.
Click here for a slide show that accompanies this paper (Slide references in the text refer to this show).
Timor Island lies close to the intersection of three major tectonic plates: The Pacific Oceanic plate is moving westwards and the Australian plate is moving northwards, while the Indonesian plate strongly opposes their motion and forms a barrier. (Slide 1)
Earthquakes result from this collision – shallow focus quakes south of Timor Leste and deeper and larger quakes to the north. Large Earthquakes recur on a 20-year timescale and can generate damaging ground movements and Tsunami. (Slide 2)
The Timor Trough, south of Timor Island, is a zone of active thrusting and convergence, but is not a plate boundary. Timor Island probably never completely separated from Australia. The Timor Trough is a classic foredeep caused by the weight of thrust sheets forming Timor Island. (Slide 3)
The Timor trough has depths ranging from 1500m to 3 km. (Slides 4-8) Deep seismic lines across the trough (Slides 9-11) show the structure of Timor thrusting over the Australian plate which is bent downwards and fractured. Large oil and gas fields are found in shallow water in ZOCA where the Australian plate begins to bend. Only small fields are possible north of this. (Slide 12)
Many subsea hazards exist to a potential pipeline crossing the trough. These include active thrust faults, seabed hollows and channels (Slide 13). Submarine landslides and avalanches are triggered by modern earthquakes and can destroy pipelines.
Timor Leste is the closest landfall, but the Timor Trough cannot be safely crossed by a pipeline, despite what some pilot studies may have said. Field developments are obliged to either be self-sufficient, or to group together on the Australian side of the trough. Different pipeline options have been proposed for landfall at Darwin or for offshore processing. (Slides 14-19)
Gas sales agreements require confidence and certainty. (Slides 20-22) Unfortunately these do not exist for Timor Leste. Political uncertainties remain over the boundaries and administration of Timor Leste’s offshore area. Technical risk applies to deep pipelines and to Offshore LNG processing. And finally, corporate risk applies to amalgamating reserves between different operators. (Slide 23)
Without positive action to resolve these Political, Technical, and Corporate risks, future developments will NOT go ahead, since many competitors exist who do not have these difficulties. We must all work together to support future national prosperity with oil and gas revenue.
Dr. Nick Hoffman received a B.Sc. degree in geophysics at the University of Edinburgh and a Ph.D. at Cambridge. He then worked as a petroleum geophysicist for BP, working on UK and worldwide projects. In 1991 he moved to Australia and joined BHP Petroleum where he specialized in Asian basins and in the Deepwater areas around the ZOC, including the Timor Trough. He is a specialist in deepwater seismic interpretation and also uses gravity, magnetics, and bathymetry to produce seabed images to study deepwater processes. He now works for the 3D-GEO group of consultant in Melbourne, Australia, and is also a Senior Researcher at the University of Melbourne where he runs research programs into deepwater continental margins and teaches seismic workstation interpretation techniques. Email: nick@3d-geo.com
