At any other time in the history of New Zealand oil and gas exploration, this week's announcements by US-based Chevron and Norway's Equinor to abandon 25,000 square kilometres of offshore exploration permits would be relatively unremarkable.

The acreage they're quitting is off the east coast of the North Island in areas where geologists know there are hydrocarbons, but where the prospect of a commercial discovery has never been high.

Few have ever explored there seriously and the fact that either company took up those permits in 2014 reflects the enthusiasm of the previous Government to encourage a larger oil