Shell health, safety, security, environmental and social performance exploration manager Grant Batterham said the owners of the vessel were on route to New Zealand and a meeting would be held tomorrow on where to base the operation.
Things under consideration included security, safety, crew and the community. The survey vessel carried 42 crew and the support craft had up to 14 crew.
The seismic survey would be conducted 150km off the coast of Dunedin and was expected to take 70 days.
The cost was in the ''tens of millions'' of dollars and was just stage one of what could turn out to be a 10-year programme if gas was found in the 21,200km sq survey area, he said.
The survey was similar to an ultrasound in which air under high pressure was released to provide sound waves down to the ocean floor. Behind the survey vessel, an 8km ''streamer'' sat below the surface, measuring the sound waves. A computer program was then used to create a 2-D image of the sea floor.
Otago Chamber of Commerce president Peter McIntyre said the visit by Shell was further confirmation the coast of Otago was of interest to both Shell and Anadarko.
''We can only hope they are successful with exploration and Dunedin becomes the base for a significant gas industry. Shell has committed to a significant large investment - large on any scale - and hopefully they find something out there.
"Our expectation is for gas, and we need to be positive about that,'' he said.
Mr Batterham, who had been in his role for about three weeks, said looking for hydrocarbons in the Great South Basin was not new.
Eight explorations had taken place in the basin between 1976 and 1983. Two had identified hydrocarbons. Both had gas and both were thought to be uneconomic.
Asked about Shell's attempt, the third major survey, he said the company was ''hopeful'' but the survey came with high costs and a high risk of failure.
The best estimate was a 30% chance of gas being found.
''It is risk and reward. If we find an economic field, it will be of benefit to the joint venture partners and New Zealand.''
There was a 1% probability of oil being found, he said. Condensate could also be found, along with the gas, but it evaporated quickly and did not develop into a thick floating mass.
Mr Batterham went to great lengths to stress Shell was a signatory to the original voluntary Department of Conservation code to minimise disturbance to marine mammals.
The seismic vessel would have a team of four independent marine observers on board who would maintain a 24-hour visual and passive acoustic watch.
If marine mammals were detected within specific zones, as defined by the code, the survey would be shut down until they had moved out of the area. The observers were also required to record data on all marine mammal observations and report the information to the department, he said.
''There is always room for improvement but we take the latest science on board.''
Shell acknowledged the protest activity around New Zealand regarding surveys and exploration. However, there were all sorts of misunderstandings around the industry, Mr Batterham said.
Gas produced about half of the carbon dioxide emissions of coal and future energy needs could be met by the use of more gas.
Already, Shell produced more gas than oil. Shell New Zealand country chairman Rob Jager said in a statement to the Otago Daily Times the company was committed to open communication with local stakeholders and to adhering to stringent safety and environmental standards to minimise potential harm to people and the environment.
''We believe that continuing community engagement and participation is crucial for developing open, meaningful dialogue and building trust.
"Our commitment is to hold regular community meetings in the areas where we operate, to listen, receive feedback and respond to queries about our business activities,'' he said.
Dunedin city councillor Jinty MacTavish still has misgivings concerning the exploration process of Shell. There was not much new coming from Shell's meetings in the city this week.
The oil and gas debate was a side issue, she said. She remained concerned the world could only burn one-third of the hydrocarbons already found and did not believe there was a need to look for more.
''I have concerns about the impact of hydrocarbons on the climate. The numbers they gave us show there is a 70% chance of finding nothing and only a 30% chance of finding gas,'' Cr MacTavish said.
