The Perth-based company said the vessel 'Geco Beta' was expected to spend up to 25 days collecting data in an area of the Otway Basin just north of Blackfellow Caves.

"We view the area as being prospective for gas rather than oil," said Woodside's senior geophysicist, Mark Taylor. "Any decision about drilling will be contingent on receiving positive results from the 3D survey."

Mr Taylor said earlier Woodside studies of the target area had shown it to be an area of particular interest to the company and a subsequent 3D seismic program in the eastern section of the Otway Basin gave it the confidence to go ahead with a drilling program, which proved to be successful. "We would hope for similar encouragement in our upcoming survey," he said.

The company has a 90 per cent stake in the project with Perth-based partner Great Artesian Oil and Gas holding the remainder.

Woodside said a successful seismic shoot could lead to an offshore well being drilled as early as 2004 with any commercial quantities of gas discovered likely be sold to South Australian and Victorian markets.