Australia has progressed from a continent considered to have little potential for petroleum resources in 1950 to a middle-order oil and gas producer on a worldwide scale in the late 1990s. The Petroleum Search Subsidy Act (1957) encouraged exploration that resulted in discoveries in the Gippsland, Carnarvon, Amadeus, Cooper, Bowen and Surat Basins. Together with the Bonaparte and Eromanga Basins, these basins are now Australias main petroleum producing regions. Subsequently, the Petroleum (Submerged Lands) Act (1967) and various State Acts were passed to manage exploration and production. In Australia, about 7750 million barrels of crude oil and condensate (1230 gigalitres) and 96 trillion cubic feet of gas (2720 billion cubic metres) had been identified to the end of 1996. The Bureau of Resource Sciences (BRS) assessed that between 1320 million barrels (95% probability) and 3440 million barrels (5%) of crude oil remain to be discovered, and between 18 trillion cubic feet (95% probability) and 58 trillion cubic feet (5% probability) of sales gas remain to be discovered. Australias most prospective crude oil basins, ranked in order, are assessed as the Carnarvon, Bonaparte, Gippsland, Browse, Perth, Otway and Eromanga, with speculative potential in the Perth Basin, Otway Basin and other basins. The most prospective basins for sales gas are ranked as Carnarvon, Browse, Otway, Bonaparte, Cooper, Gippsland and Perth Basins. Australias likely ultimate crude oil resource was assessed as being about 52% depleted and sales gas resource as about 10% depleted at mid-1997 (BRS 1998). However, because of the relatively low level of exploration in Australia it is impossible to estimate how long the petroleum resource will last. Approximately 94% of crude oil production and 75% of gas production are from offshore. New production is likely to come mainly from already-known basins with contributions from deepwater areas and possibly the Exclusive Economic Zone.
