At the time of the Maari final investment decision in late 2005, the forecast capital expenditure was $US365 million.

Bringing the 50 million-plus barrel oil field into production will involve five production and three water-injection horizontal wells, plus the wellhead platform and a floating production, storage and offloading vessel.

Horizon chief executive Brent Emmett told the Wilson HTM Oil and Gas Conference in Brisbane on Monday that Maari, located about 50km off the south Taranaki coast, was forecast to generate about US$80 million per month of earnings before interest taxation, depreciation and amortisation if crude oil was priced at $US80 per barrel.

He said the wellhead platform - on the Dockwise Blue Marlin heavy lift vessel - was currently under tow from the Kencana yard in Lumut, Malaysia, and is expected in New Zealand waters later this month. The Blue Marlin is also expected to install the wellhead platform.

The conversion of the Raroa FPSO in the Jurong shipyard, Singapore, has also been completed and the vessel is expected to be at the Maari wellsite later this month or next.

The Ensco 107 jack-up drilling rig - presently drilling the Kupe development wells, plus the Momoho well and sidetrack further north - should be ready to start Maari development drilling in June, according to Emmett.

The rig will also appraise the possible reserves from other Maari zones and from Manaia during the development drilling phase of the field.

First commercial oil production from Maari is expected in the third quarter of this year.

A Wilson HTM report earlier this year found there was considerable upside potential within the Maari licence with the M2A sands zone above the main Moki sands structure at Maari had upside potential of about 12 million barrels.

The Maari partners are operator OMV NZ (69%), Horizon Oil (10%), Todd Petroleum Mining (16%) and Cue Energy Resources (5%).