Dr Henry, who is a marketing lecturer at the University of Otago's School of Business, said Dunedin was "pretty well at the centre of where exploration is".
His audience of engineers, accountants, lawyers, consultants, restaurateurs, plumbers and local government politicians and employees asked questions about the scale of the exploration work, where it might lead and how Dunedin might benefit.
Dr Henry said clothing manufacturer and retailer Hallensteins had proved during the gold rush there was more money in servicing an industry than in actually doing the job.
He suggested Dunedin could gain "at least" 3000 highly paid jobs, or more, if a substantial oil field off the coast went into production and the city was chosen as the supply base.
Asked how big offshore oil reserves were, Dr Henry said the fields "as known" were equivalent to the North Sea.
Five separate ventures are exploring the Canterbury and Great South basins, using seismic testing.
Dr Henry considered that the use made of Port Otago by the seismic vessels already indicated Dunedin was providing the service oil companies were looking for.
A consortium that included the Dunedin City Council, Port Otago, Dunedin International Airport, Engineering Dunedin and the university has created a booklet and DVD promoting the city to international oil companies.
Dr Henry said while such promotion was needed, oil companies did not like people "in their face". They preferred a "soft approach".
The DVD, narrated by Cr Dave Cull, says Dunedin is "the ideal location for your logistics and supply base."
Its final words are: "Dunedin is ready and waiting for you."
The only reference at the seminar to the Gulf of Mexico oil spill was a question about which way the ocean currents ran off the Otago coast.
Dr Henry said they ran south to north and away, towards the Chatham Islands.
