EXPLORATION IN PERMIT NSW/P10 IN THE OFFSHORE SYDNEY BASIN

Abstract

The offshore Sydney Basin is unique frontier acreage because it is adjacent to Australia's largest gas and petroleum market on the east coast of New South Wales. Although the onshore Sydney Basin has been tested by more than 100 petroleum exploration wells, no wells have been drilled offshore.New South Wales Permit NSW/P10 has an area of 9419 km2 and extends over the offshore northern and central Sydney Basin which contains Upper Carboniferous to Middle Triassic lithiclastic and siliciclastic sedimentary rocks and volcanics. Maximum depth to magnetic basement in NSW/P10 is greater that 9 km in the southern Macquarie Syncline and south of the New England Fold Belt at the continental margin. Recent seismic reprocessing and aeromagnetic surveying have focused the exploration effort on northern NSW/P10 where thick (greater than 1600 m) Upper Permian section containing source and reservoir facies is predicted. Other areas in the permit are less prospective because of widespread intrasedimentary magnetic bodies or the absence by erosion of Upper Permian and Triassic section.The Sydney Basin is an exhumed basin that reached its maximum depth of burial in the Early Cretaceous prior to basinwide uplift of 1.5-3.5 km during the Tasman Sea rifting. The magnitude and timing of the exhumation can be demonstrated with fluid inclusion, magnetisation, fission track and vitrinite reflectance data. The presence of commercial quantities of oil or gas in Upper Permian reservoirs depends on trap integrity having been maintained during the epeirogeny, or the re-migration of hydrocarbon into new traps.