Results of a delayed drilling programme at the Hoki wildcat well off Taranaki should be known around the end of the month.
Drilling resumed on Monday following a three-week delay caused by problems with the Kan Tan IV rig.
The Hoki-1 well is about 135km west of New Plymouth in
water depth of 330m. It is one of the deepest wells in the region.
Analysis by McDouall Stuart found that although chances of commercial success were between 10 per cent and 15 per cent, the field's operator, AWE has said it had the potential to contain 250 million barrels of oil.
"In the event [albeit unlikely given Hoki's wildcat characteristics] that a commercial discovery is made, the probability would be that it is larger than Tui and perhaps substantially so," McDouall Stuart says.
Tui has about 50 million barrels of oil.
New Zealand Oil & Gas Ltd has a 10 per cent stake in the Hoki project and describes the delay as frustrating.
A spokesman yesterday said repairs to the drilling mast were required and questions were now being asked of the rig's operator, Maersk Drilling, why they had not been carried out earlier.
Drilling should be completed within two weeks. The well is planned to be drilled to a total depth of 3570m.
The participants in the joint venture are AWE, with 50 per cent; OMV New Zealand, 21.25 per cent; Todd Energy, 18.75 per cent; and NZOG (through its subsidiary Petroleum Resources), with 10 per cent.
McDouall Stuart estimates that in the event of a failure NZOG would face a write-off of around $5 million.
Following drilling at Hoki the Kan Tan IV will move to two new targets in and near the Tui field and then on to an Origin Energy prospect further north.
* Greymouth Petroleum's Chilean subsidiary PetroMagallanes has found gas at the Clarencia 1A well in the Caupolican Block, located on Tierra del Fuego. It says it is confident the discovery will lead to a declaration of commercial exploitation.
