NGC said the appointment was an important milestone that would lead to a firm conclusion on the Maui gas reserves.

The gas industry will then have a much clearer picture on the overall gas supply position and participants will be able to develop their plans with greater confidence, the company said.

It is understood Netherland Sewell has not previously worked on any major New Zealand oil industry projects and that the Maui redetermination package will involve a substantial team, probably involving personnel from both the Houston and Dallas offices, working essentially full-time for several months.

The Netherland Sewell appointment, their investigation and subsequent report could end up costing the Maui contract parties $NZ2 million or more if, say, a 10-strong team spends three months conducting due diligence and another month writing up their results.

Netherland Sewell's conclusions should bring to a close the Maui redetermination matter, which could have turned into the most prolonged and bitter battle the New Zealand energy industry had seen for years. All parties to the Maui gas contracts have agreed to abide by the report's recommendations.