Oil and gas reserves in this country's largest petroleum field at Pohokura, offshore from New Plymouth, have both been lifted.
The Ministry of Economic Development's latest Energy Data File shows the field's oil reserves up 38 per cent from 44 million barrels to 61.6 million barrels.
Pohokura's totalgas reserves have grown by 24 per cent to 978 billion cubic feet from 791bcf.
Total remaining gas reserves in this country, including upgraded reserves in producing fields as well as estimates from fields still to come into production, increased 17 per cent to 2413bcf at the start of 2008 from 2061bcf a year earlier, Crown Minerals said.
Coal seam gas was included in gas reserve estimates for the first time this year, with the MacDonald coal seam gas field being developed near Greymouth being listed.
Total remaining oil reserves in New Zealand increased 12 per cent to 217 million barrels from 193 million barrels.
Over its lifetime, Pohokura would yield more oil in the form of condensate than crude oil from either the Tui field which recently revised its total reserves up to 50.1 million barrels, or the Maari field now being developed which had a current reserves estimate of 49 million barrels, Crown Minerals said.
Production of condensate at Pohokura rose to 4.7 million barrels in the latest year from 900,000 barrels in 2007.
The Pohokura field is operated by Shell, which has a 48 per cent stake, with partners OMV and Todd Energy, which both have 26 per cent.
