The ship, with an international crew of 50 on board, has been using a $13 million installation of 3D seismic scanning equipment to map the sea floor 50km east of Dunedin since early January.
Yesterday, Origin Energy manager of exploration operations Neil Millar confirmed the mapping operation - the largest seismic exploration survey the company had undertaken - was complete.
The vessel had returned to Dunedin to refuel on Saturday, and was now heading across the Pacific on its way to its next job in Norway, he said.
The ship is owned by Norwegian-founded multinational company PGS (Petroleum Geo-Services) but was contracted to Australian-listed oil company Origin for the duration of the mapping operation.
Up to 30 terabytes of raw data collected by the vessel's equipment had been sent to a data processing centre in Perth, he said.
However, it was likely to take more than six months to turn the data into a final 3D image - similar to an ultrasound - showing the geology of the sea, up to 10km below the sea floor, which would then be analysed by Origin geophysicists looking for signs of hydrocarbons.
"It could be some time before Origin makes a decision whether to drill a well in the area," Mr Millar said.
During mapping, the vessel made more than 100 passes of the 1150sq km of sea floor while towing imaging equipment in six "streamers" trailing up to 5.1km astern.
The operation had remained on schedule despite some "challenging" conditions, he said.
Large swells had forced the postponement of the survey on several occasions, with swells of more than 5m prompting the ship to return to Dunedin and refuel in early February.
