The promotional tour also included meals at prestigious restaurants Logan Brown and Martin Bosley.
The oil representatives paid for their own flights, and were given a presentation on New Zealand's regulatory regime while they were here.
Green Party co-leader Russel Norman said National appeared to have a "bottomless slush-fund" for "big oil".
He said Energy Minister Simon Bridges was giving oil industry executives first class treatment while "our precious environment gets third class treatment".
Energy Minister Simon Bridges has described the spending as an investment because royalties from oil profits went into public infrastructure such as schools and hospitals.
Two of the hosted companies - Norway's Statoil and Australia's Woodside - have sought and been granted exploration permits in New Zealand.
Mr Bridges has confirmed that no jobs have been created as a result of these exploration permits, but said the companies planned to invest millions in this country.
He also said the budget for the summit was "very modest".
Dr Norman responded: "The extend of National's indulgence shows just how out of touch it is with ordinary people.
"It's offensive to New Zealand families struggling to get by for their money to be used on yachting and wine tasting for foreign oil executives."
Greens say they would ban deep sea oil drilling and raise oil industry royalties if elected.