Aussies look to big prizes in NZ

AUSTRALIAN companies Origin Energy and Australian Worldwide Exploration have high hopes that their respective offshore New Zealand exploration programs will yield large oil, condensate and gas finds over the next few years.

AWE New Zealand exploration manager Eric Matthews told the 2008 New Zealand Petroleum Conference in Auckland today that there were no secrets to AWE's strategy for offshore Taranaki.

"Our strategy is to explore more in and around our Tui Area mining permit and to find more oil on the Western Platform that we believe is an oil play, not a gas play," he said.

AWE is the dominant permit holder in offshore Taranaki, with several permits surrounding the Tui Area oil pools that have produced about nine million barrels of oil in seven months of production.

Matthews said there were widely distributed late Cretaceous Rakopi coally measures, about 1000m thick in parts. Those coals had about 4500m of sediments above them.

Although there was quite a lot of shallow, non-biogenic gas, AWE still believed the main prize remained more oil charged from the Tane Trough.

Matthews said last year's Kopuwai-1 well, which encountered a poor quality oil column in the Eocene-aged Kapuni F Sands, had demonstrated charge from Tane. The earlier Pukeko-1 well further south also had oil shows.

AWE and its various partners could drill perhaps several more offshore Taranaki wells using the semi-submersible Kan Tan IV in 2009, according to Matthews.

The strongest candidates were Hoki-1, although the Paua, Toke and Mataku leads were also possibilities.

Paua was a Pliocene Mangaa sands play, involving draping/mounding; Toke was a Cretaceous North Cape play, featuring intrusive doming; Matuku was a Paleocene Kapuni compression play.

Matthews said AWE hoped to replicate its success at Tui, where initial estimates of 2P recoverable reserves had gone from 26.8 million barrels (pre- drill) to 41.7MMbbl after all subsurface data had been re-evaluated after the four development wells had been drilled.

Origin Energy exploration professionals were also bullish on their company's New Zealand prospects.

Principal geophysicist Wayne Mogg said Origin held high hopes for its two offshore Canterbury licences PEP 38262 and 38264.

While few wells had been drilled in this region, some had encountered good oil and/or gas shows.

The 1985 Galleon-1 well had tested about 2240 barrels of condensate and about 10.6 million cubic feet of gas per day. The Clipper-1 well encountered a gross 56m hydrocarbon interval, while the latest well, Cutter-1 also had some shows in the Eocene.

Mogg said Origin had shot several thousand kilometres of 2D seismic and some hundreds of square kilometres of 3D in the basin over the past two years.

Many prospects had been identified, including the Carrack and Caravel structures, with closures of and respectively.

"Carrack and Caravel have the potential to host several Tcf of gas or many hundreds of million barrels of oil," he said.

Origin does not yet have definite drilling dates, amd a decision whether "to drill or drop" half the permit acreage must be made later this year.

The company also believes its two offshore Northland Basin blocks are highly prospective.

Origin staff geologist Kay Bierbrauer told delegates that there was no distinct geological boundary between the Taranaki and Northland basins, and Origin's latest seismic had showed some giant structures at or near the Oligocene level in licences PEP 38618 and 38619.

The best seemed to be the Korimako South prospect, which had strong amplitude and AVO anomalies, and Tarapunga, that had some similarities to Todd Energy's Karewa gas discovery in northern Taranaki.

"We are working on several opportunities that have large upside potential," he said. "We are preparing to drill once we have some more results, in 2010."