NZOG's announcement comes a day ahead of its annual shareholders meeting in Wellington. The company's shares closed yesterday at 42 cents apiece, having fallen 40 percent in the last year, a period in which global oil prices have settled at new, much lower levels than were previously prevailing.
The local oil and gas explorer said its 15 percent share of Kupe developed reserves at June 30 stood at 4.4 million barrels of oil equivalent (boe) and 4.2 million boe after production since then. That total now stood at 5.6 million boe, a 34.7 percent increase.
Light oil volumes of 1 million boe was a 43.2 percent increase, while natural gas reserves now stood at 23.3 petajoules, a 34 percent rise from June. NZOG's share of the field's developed reserves of liquefied petroleum gas (LPG), now stands at 97.4 kilotonnes, a 28.7 percent uplift.
Its share of undeveloped reserves is still believed to sit at 3.2 million boe, the company said, with further work "to assess options for developing potential additional reserves."
"The additional work may provide material additional reserves, provided economic assessments support development," said Knight.
Genesis holds at 31 percent share in Kupe, Origin holds 50 per cent and Japanese multi-national Mitsui holds at 4 percent share.