DEEPWATER AND FRONTIER EXPLORATION IN AUSTRALIA—HISTORICAL PERSPECTIVES, PRESENT ENVIRONMENT AND LIKELY FUTURE TRENDS

Australian deepwater (>500 m) basinal areas are generally extensions of known shallow-water basins, filled with non-marine to marginal marine sedimentary facies. True deepwater sedimentary facies are found in very few of these basins. In Australia, the transition to deep water is often associated with the edge of thick, prograding Tertiary carbonates, which have buried the inboard sediments and promoted recent hydrocarbon generation.Of ~1,040 offshore exploration wells, only 61 have been drilled in deep water, and only one in depths greater than 1,500 m. Most deepwater exploration drilling has occurred on the greater North West Shelf. About 9.4 billion boe of recoverable deepwater resources have been discovered since 1979, of which 94% is gas and 6% liquids. Elsewhere in Australia, deepwater drilling has been sporadic, with only seven wells drilled on the entire southern margin, and none on the southwestern or eastern margins, due to perceptions of limited prospectivity or limited accessibility. The northern basins of Australia lie predominantly in shallow water.An unprecedented amount of deepwater exploration activity will occur in the next three years, with more than 17,500 km of 2D, 14,300 km2 of 3D, and 36 wells committed. Secondary term (variable) commitments comprise a further 5,200 km of 2D, 1,200 km2 of 3D and 24 wells. The challenges for exploration of Australia’s frontier deepwater provinces include identifying new petroleum systems capable of hosting large fields, and working in harsh, remote and high-cost operating environments. Government-sponsored initiatives should encourage future uptake of the frontier areas.