A somewhat unusual manner of handling the exploration of a 64,000-sq-mi offshore area in Bass Strait, Australia, has resulted to date in 7 major and 2 minor discoveries out of 16 "new-field" wildcats. In addition, numerous stepout wells, all successful, have been drilled. Each of these wells was drilled offshore from the coast along which 140 onshore dry holes had been drilled in unsuccessful exploration for oil during the past 44 years.

Reasons are expounded why, despite the discouragement onshore, this particular offshore acreage was selected, and why a special manner of handling the exploration was followed.

The results of the exploration illustrate facts of oil occurrence which apply generally in young coastal basins, as is demonstrated repeatedly by rapidly growing worldwide offshore exploration. Geological analysis,

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supported by various fundamental measurements, makes it clear that the best part of most of the world's Cretaceous-Tertiary coastal basins lies offshore. Reasons for this are discussed.

Australia has approximately the same area as the 48 conterminous states of the United States, and it has similarly extensive sedimentary basins. Significant comparisons are made, as between the largely Paleozoic basins on the land and the younger basins along the coasts.

In the search for oil on the Australian continent, about 2,000 wells have been drilled, and several tens of thousands of bores have been drilled for water in the sedimentary basins during the past 80 years. This effort was without commercial petroleum discovery prior to 1962. From 1962 on, several discoveries of oil and gas have been made on the land. The first offshore discovery was made in Bass Strait in 1965 in the first well drilled in water off the Australian continent.

Current proved petroleum reserves in Australia are of the order of 2.5 billion bbl of crude and natural gas liquids, and 11 trillion cu ft of gas. About 92 percent of the oil and 64 percent of the gas have been found in the Bass Strait offshore.

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