Publication: Eastern Australian Basins Symposium 2001
Authors: V. Stagpoole, C. Uruski, R. Funnell and D. Darby
Date Published: November 2011
Number of Pages: 28
Reference Type: Magazine Article
Abstract:The petroleum potential of the Deepwater Taranaki Basin was recognised after a high quality multi-channel seismic reflection line was acquired over the basin in 1996. Interpretation and modelling of this line extends
the prospective area of the Taranaki Basin, New Zealand's most commercially successful petroleum province, into the 80,000 km2 deep-water region (up to 2,000 m) to the west.
Interpretation of sedimentary facies and potential source rocks in the Deepwater Taranaki Basin is essentially based on reflection characteristics, well ties and our geological knowledge from exploration of the shelf and onshore Taranaki. The principal source rocks are interpreted to be Cretaceous rift sediments comprising terrestrial and paralic coal measure sequences, silts and sands with a potential oil yield of 150 - 280 bbl/acre-foot (from Taranaki Basin). Potential reservoirs include Cretaceous transgressive shoreline sands that overlie the source rock formations, and deepwater turbidite sands around the basin margins. Cretaceous sediments in the Deepwater Taranaki Basin appear to be up to 5,000 m thick, indicating a particularly large gross thickness of
potential source rock. Typically, a further 2,000 to 4,000 m of Cainozoic strata containing abundant siltstone and carbonate sealing rocks, overlie the Cretaceous succession.
A basin model, using rock types based on this interpretation and calibrated to the nearest Taranaki Basin wells, predicts that in the deepest parts of the basin, expulsion of petroleum began in the Late Cretaceous (c. 90 Ma) and continued into the Early Cainozoic (c. 45 Ma). Sufficient seals are developed by the Early Cainozoic to trap hydrocarbons and limit leakage. Models show that accumulations at several levels, principally in latest Cretaceous reservoirs, persist through to the present day. Where suitable structures can be found following further seismic acquisition, modelling predicts that significant quantities of petroleum will still be trapped today, making the Deepwater Taranaki Basin one of the most attractive frontiers for Exploration in eastern Australasia.