United States oil explorer Anadarko Petroleum is to contribute US$30 million towards exploration of oil and gas prospects about 65km off the coast of Dunedin - and may help send a deep-water oil rig to the area.

Australian-listed Origin Energy, which holds the exploration permit covering the Carrack and Caravel prospects, said Anadarko's would take a 50 per cent interest.

Origin completed a hydrographic seismic survey of the Carrack and Caravel prospects last year, covering about 300sq km within the southern point of the Canterbury Basin.

Anadarko had since paid for specialist processing of the seismic survey material, Origin's executive general manager for geo-science and exploration new ventures Rob Willink said.

"The joint venture [through New Zealand subsidiaries of Origin and Anadarko] will now move forward to secure a suitable rig for the drilling of an exploration well, most likely in 2011," Willink said.

The prospects might hold more than 500 million barrels of oil (and gas) equivalents.

Petroleum Exploration and Production Association chief executive John Pfahlert welcomed the decision, especially in that it meant Origin had "introduced" a new exploration company to New Zealand.

He said a one-hole deep-water drilling programme was likely to cost between US$75 million and US$100 million, with costs beyond Anadarko's US$30 million contribution shared among the joint-venture partners.

Anadarko Petroleum Corporation, listed on the New York Stock Exchange with a market capitalisation of US$36 billion, is one of the largest independent oil and natural gas exploration and production companies in the world.

It is the largest independent deep-water producer in the Gulf of Mexico, and has production or exploration activities under way in Alaska, Algeria, Brazil, China, Indonesia, Mozambique and West Africa, having last year reported record sales of 220 million barrels of oil (and gas equivalents).

Willink highlighted Anadarko's experience and proven capability in deep-water exploration and production work.

Origin's exploration programme in the Canterbury Basin followed that of Australian consortium Tap Oil and Australian Worldwide Exploration's efforts in southern waters in late 2006.

Pfahlert said the deep-water test-drilling rig used for the Origin programme could potentially be co-contracted by permit holders in the Great South Basin.

Willink said Origin was keen to share rig mobilisation and demobilisation costs with other operators wanting to drill in the vicinity.

Crown Minerals has spent about $7 million gathering southern seismic data and is expected to spend another $3 million in the region this year.

Anadarko Petroleum:

* One of the world's largest oil and gas exploration companies.

* Has 2.3 billion barrels of oil reserves.

* Operates in the Gulf of Mexico, Alaska, Algeria, Brazil, China, Indonesia, Mozambique and West Africa.

* Listed on New York Stock Exchange with market capitalisation of US$36 billion.