"The Otway Basin is regarded as the second most prospective basin in South Australia after the Cooper Basin - Australia's largest onshore oil and gas producer," Holloway said.

The OT2008 A, B and C blocks are being offered to explorers on the basis of work program bidding. Bids close at 4pm Thursday November 27 and the winning bidders are to be announced in early 2009.

OT2008-A covers 1173 square kilometres in the Robe Trough. It has three previous exploration wells and 1006 km of 2D seismic. One well in the area (Camelback-1) had significant gas shows but lacked good reservoir.

OT2008-B covers 1580 square kilometres around the Jacaranda Ridge oil/condensate discovery in the Tantanoola and Penola Troughs. There are 10 previous wells and 2045 kilometres of 2D and 160 square kilometres of 3D seismic in the area. It contains a continuation of the Jacaranda Ridge condensate/oil trend, and the main gas producing area (PPL 62) of the Katnook Graben lies directly to the east of the block. The retention licence over the Kilanoola oil field is not included in the licence.

OT2008-C covers 767 square kilometres in the Penola Trough and has nine previous wells and 1161 kilometres of 2D and 265 square kilometres of 3D seismic in the area. Five commercial fields and one retention licence surround the block in separate petroleum licences, and are not included in the release block. Sawpit-1, which lies in the block, recovered 1.5 barrels of 32-35o API oil from fractured basement on test in 1992.

Some potential exists for larger hydrocarbon accumulations than found so far in the onshore Otway Basin, according to the department of Primary Industries and Resources of South Australia.

"Re-interpretation of well and seismic data by. has shown the structural evolution of the onshore and offshore Otway Basin is analogous to basins elsewhere in the world found to contain giant oilfields," PIRSA said.

For more information see www.petroleum.pir.sa.gov.au