Minority partner New Zealand Oil & Gas this morning said that a detailed field reassessment by AWE had increased proven and probable (2P) reserves for the oil pools of Tui, Pateke and Amokura from 47MMbbl to 50.1MMbbl.

NZOG said its 12.5% share of additional reserves had a gross value of about $NZ70 million ($A56 million) using current oil prices and exchange rates. This would mean the total additional reserves have a gross value of almost $A450 million.

Total production, for the 2007-08 financial year has been increased from 13MMbbl to 14.2MMbbl while production for the 2008-09 financial year was now forecast to be 9MMbbl, NZOG added.

NZOG said Tui continued to perform above expectations, with production so far this month averaging 42,500 barrels per day, compared with the pre-production forecast of less than 18,000bpd.

Today's announcement follows last month's reserves upgrade from 41.7MMbbl to 47MMbbl.

Meanwhile, NZOG said that an additional development well, Tui-4H, and several near-field exploration wells were planned for early 2010 that could be tied back to the Umuroa in the event of success.

The Tui partners are operator AWE (42.5%), Mitsui E&P New Zealand (35%), New Zealand Oil and Gas (12.5%) and Pan Pacific Petroleum (10%).