A new deepwater frontier could be emerging offshore eastern Australia after a fresh geological discovery unexpectedly made by a joint Australian-French survey.

The survey hit on promising results in the Fairway Basin - and this could lead to a whole new batch of offshore licenses within the next few years in a part of the world not previously noted for its hydrocarbon potential.
The mapped area itself lies across French and Australian territory, and the Australian Geological Survey Organisation (AGSO) is already optimistically indicating (as might be expected, of course) that the Fairway Basin may prove as significant to the Australian E&P industry as the North West Shelf if future exploration confirms the presence of petroleum-rich rocks in the sedimentary domes.
The basin, about 500km north-northeast of Lord Howe Island and 1,000km east of Brisbane, and south of New Caledonia, is administered by France. "Around 100 large sedimentary domes were discovered buried under the seabed in the Fairway Basin, where water depths are 1,800-3,500m (5,870-11,413ft)," said AGSO.
Many of the domes are 1,000m (3,261ft) high and more than 10km long and contain sediments dating back 100 million years. Presence of such domes in the Fairway Basin makes the area a very favorable one for exploration, noted AGSO.
According to Dr. Neville Exon, AGSO's research coordinator, International Activities and Sea Bed Mapping, which participated in the survey, follow-up surveys are likely to take place in 2001 in an effort to determine more closely the potential of the region.
He added that Elf Aquitaine and IFP were thought to be seriously considering becoming involved.
"This discovery of salt or shale diapirs was an absolute surprise to us, and means that we now have some very positive information about an offshore basin about which we knew almost nothing two years ago," Exon told Hart's E&P.
However, it is too early to give any indication of possible hydrocarbon reserves, and the first well could be five years away, he said, while noting: "The results to date do suggest some real medium-term potential."
Given the water depths involved and the lack of land and infrastructure in the region, fields would need to be of a very large size to warrant development, which would have to involve floating production facilities, said Exon. With the advance of gas-to-liquids technology for producing marginal gas deposits, this could perhaps be one way forward for any reserves discovered.

Assessment program
In advance of the follow-up work, AGSO intends to start a program within the next few weeks aimed specifically at the petroleum assessment of Lord Howe Rise.
Summarizing the large deepwater Fairway Basin, which lies on a submerged continental ridge, the seabed mapping specialist said: "Very large areas are now known to have geophysical evidence of a thick sedimentary sequence, gas hydrates and large salt or shale domes of probable Cretaceous age. Further work by researchers may well lead to companies taking up petroleum exploration leases there in a few years' time."
Meanwhile, Warren Entsch, parliamentary secretary to the Minister for Industry, Science and Resources, described the survey as excellent news for Australia's petroleum industry which Hart's E&P has already tipped for its long-term potential (see November issue, page 153). "Not only are the preliminary results a very positive sign for our industry, this is all the more exciting for being such an unexpected discovery," he said. "It shows the importance of the geoscientific research conducted by the Australian Geological Survey Organization in little known offshore areas.
"We still have a great deal to learn about this area," said Entsch. "Finding such significant potential targets for petroleum search boosts not only the petroleum exploration industry, but marks a great advancement of our scientific understand-ing of the Lord Howe Rise.
"The age of the sedimentary rocks is extremely significant. Their oil-bearing potential was apparently enhanced by being periodically connected to the open sea early in its formation. We are talking here about a period between 100 million to 150 million years ago when Cretaceous salt or shale formed in the early stages of rifting between the Lord Howe Rise and the Norfolk Ridge."
More than 90,000sq km was mapped during the cruise in the northern Fairway Basin and easternmost Lord Howe Rise. Although only 5,000sq km of mapping was conducted in Australian waters, preliminary results suggest the large southern Australian part of the basin may also be potentially rich in oil and gas.
The discoveries were made during a recent geological research cruise conducted jointly by French and Australian scientists from IFREMER, the premier French marine research institute, AGSO and James Cook University. Research teams from AGSO and French and New Caledonian institutions will continue to carry out research in the area.