Polarcus is carrying out a three-week, three-dimensional 600sq km seismic survey of the seabed, understood to be costing $8 million to $10 million, for listed New Zealand Oil and Gas, around the Clipper oil and gas prospect.
NZOG external relations manager John Pagani said when contacted Sealink would be supplying Polarcus, which under other contracts had visited Dunedin in the past, but would not be putting into Dunedin this time.
A year ago, Brazilian oil giant Petrobras exited its New Zealand permits.
Its seismic survey vessel Orient Explorer was dogged at sea by Greenpeace and other protesters, but a subsequent controversial law change raised the penalties against protesting at sea.
During the 3-D survey off Oamaru, Polarcus has 12 sensor streamers, 100m apart and each trailing the vessel by 8km, picking up acoustic soundings, with cautions being relayed to other shipping on maritime radio.
Mr Pagani estimated the data collected would go into a queue for processing in Perth and could take take up to six months to complete.
After that, geo-scientists could take up to a year to analyse the findings.
The Clipper prospect is one of several off Oamaru's coast which have attracted attention during the past more than two decades, including other adjacent prospects Barque, Caravel and Carrack, but none of which have delivered commercially viable exploration or test results.
Sealink 161 is 60m long by 14m wide and variously listed as a supply ship and anchor-handling vessel, with a large, flat aft-deck.
The vessel's arrivals and departures are confidential and tight security has been in place in the boat's upper-harbour berth in Dunedin.
In late November, in a joint venture with OMV New Zealand, the drill programme operator and 65% shareholder, and Octanex (22.5%), NZOG (12.5%) began test-drilling off the Taranaki coast.
The oil rig Kan Tan IV began drilling at Matuku-1, in 130m of water, and is expected to take about 45 days to drill to a depth of 4750m.
Shell is yet to make a final decision whether to drill, or drop, its Southern Ocean exploration permit, but separately is scheduled to go ahead with a two-dimensional, 70-day seismic survey south of Dunedin in the Great South Basin, in January.
•Texas-based Anadarko's contracted drill ship Noble Bob Douglas is still drilling off the coast of Taranaki. Next, it would drill a hole off the Otago coast in late January or February, but no final decision on the date had been made, a spokesman said yesterday.
