The operator, Austrian oil giant OMV, says the production plateau rate from the field, south of Maui, is aimed at 35,000 barrels of oil per day (bopd).

Current estimates of the P50 field reserves are about 50 million barrels with a field life exceeding 10 years, said OMV executive board member responsible for exploration and production Helmut Langanger.

"This is a major step forward in strengthening our position in one of our international core areas," Langanger said.

“With the Pohokura gas field development project well underway and now the Maari oil field development being approved, New Zealand is a country where OMV has a high level of development activities."

The Maari field was discovered in 1983 in 100m of water, some 80km off the south Taranaki coast. The main reservoir, the Miocene-aged Moki formation, flowed over 3650 bopd during a Maari-1 production test.

Langanger said the agreed scheme was a sound development plan. The partners had applied to Crown Minerals for a petroleum mining permit, which was expected to be granted soon.

All the major work scopes had been tendered and tender evaluation was nearing completion. The development contracts are expected to be awarded within the next few weeks.

The development work scope comprised a normally unmanned wellhead platform, a FPSO for the processing and storing the crude oil, five production and three water injection wells.

All wells would be drilled from a common seabed location, with the wellheads located on the fixed wellhead platform for easy access for routine and unplanned well interventions during the field's life.

The platform would have spare slots for future platform wells and would provide the facility to tie-back any satellite fields.

Earlier this month, Horizon Oil told the ASX it had already made its positive final investment decision and had development finance of up to US$40 million approved with Bank of Scotland subsidiary BOS International.

Horizon has also reported a July 2003 independent report, by Perth-based Resource Investment Strategy Consultants, which said likely recoverable reserves for Maari were 49 million barrels of oil from the Moki and Mangahewa reservoirs, plus the M2A sands. There was additional upside potential of a further six million barrels from the Manaia prospect to the southwest.

The Maari (PEP 38413) partners are: operator OMV NZ (69%), Horizon Oil (10%), Todd Petroleum Mining (16%) and Cue Energy (via Highlands Oil & Gas) (5%).