Seismic survey finished

New Zealand Oil & Gas says it has completed an incident-free 3D seismic survey covering approximately 650 square kilometres of the "Clipper" permit east of Oamaru.

Early in December, NZ Oil and Gas chief executive Andrew Knight said the company was planning seismic investigations for an area off the coast of South Canterbury, colloquially known as the Clipper.

"Oil and gas prices are more favourable now than they were back then [earlier drilling], and the safety technology has improved markedly . . . this is potentially a very exciting opportunity, " he said then.

The seismic vessel Polarcus Alima began the survey on December 17 towing 12 seismic streamers, each 100 metres apart and reaching eight kilometres behind the vessel, NZ Oil & Gas said.

The survey was completed on December 31, more than a week ahead of schedule. The terms of the Clipper exploration permit required a 3D survey to be completed by October 2014.

The Clipper permit is a joint venture with the Australian-based Beach Energy. NZ Oil and Gas bought into the permit in October 2012. The company has said if there is a "decent show" at the site, it would "find partners" for a possible drilling operation.

Extensive seismic surveys were conducted in the Canterbury Basin in the 1970s and 1980s before the only existing well in the block, Clipper-1, was drilled by BP in 1984. It recovered samples of hydrocarbon gas from a depth of over 4000 metres.

Data from the survey would be processed overseas and then analysed by New Zealand Oil & Gas geoscientists in Wellington. That process could take one to two years.

The Clipper and Galleon permits lie in the Canterbury Basin, which is a focus for frontier, conventional oil and gas exploration. Drilling by another operator was scheduled in an adjacent permit in early 2014, NZ Oil & Gas noted. A seismic survey is a method of testing the earth's physical properties using acoustic or sound waves similar to ultrasound. Data collected is analysed to create an image of the subsurface, which helps to determine whether prospects to drill exist and to resolve the location of any potential exploration well.

New Zealand Oil & Gas has a 50 per cent interest in Clipper and is the operator. The remaining 50 per cent is held by ASX-listed Beach Energy.

NZ Oil & Gas' Knight said he wanted to thank the local community. "Tangata whenua, the Department of Conservation and community representatives enabled a successful survey to occur with no impact on the marine environment."