The family-owned Todd Energy will be contributing $NZ26 million to the total estimated cost of drilling the onshore and offshore wells, all of which are in the Taranaki Basin.

Todd Energy chief executive Richard Tweedie is thrilled with the program. "This is big by our standards and will be the busiest and most concentrated period exploration we, or New Zealand for that matter, have seen for quite some time," he told EnergyReview.Net from Wellington today.

Tweedie said it was great to be involved in so much exploration at a time the country urgently needed to discover further oil and gas reserves to replace the rapidly depleting Maui field.

While EnergyReview.Net has reported on nearly all the planned wells during the past few weeks, Todd Energy has revealed some interesting details regarding the targeted formations and the hopes of the various consortia involved.

Tweedie said Todd Energy's interests in the wells ranged from 10% to 100% and targeted formations ranged from the shallow Miocene-aged Moki, Mt Messenger and Manutahi sands to the deeper Eocene-aged Kapuni formation.

One of the wells, the deviated Pohokura South-1A well, had already started from the onshore licence PEP 38705 to test the southern limits of the 1tcf Pohokura gas-condensate discovery; while the recently-arrived Ocean Bounty semi-submersible rig was about to start the offshore Pohokura-3 well to test the northern extend of that field.

After Pohokura-3, the Ocean Bounty will move north to off Port Waikato, near the edge of the Taranaki Basin to drill the Karewa-1 well, the second commitment well in PEP 38602 for Conoco, Todd and Inpex Petroleum. The partners will be targeting a prospect with some similarities to the offshore Maari oil discovery further south and will be drilling into a late Miocene target, at a depth of about 2000m.

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The Ocean Bounty will then move south to drill the Maari-2 appraisal well in PEP 38413 for Austrian firm OMV Petroleum and Todd Energy. This well will be drilled on the southern flank of the field and be aimed at increasing the level of certainty about the size of the field's recoverable reserves in the main oil reservoir, the Miocene-aged Moki formation. Following a successful result, detailed planning to develop the field will begin.

Todd Energy and long-time partner Shell New Zealand are to drill two wells in the onshore south Taranaki Kapuni field, this country's first modern-day petroleum discovery, from early 2003. One will be the Kapuni-16 well, to appraise and develop the productive K1 reservoirs on the eastern flank of the field. This well had been located on the basis of interpretation of 3-D seismic and if successful would add "substantial", unspecified new gas-condensate reserves, said Tweedie.

The other will be Ngarewa-1, an exploration well targeting an amplitude anomaly in the shallow Miocene-aged Mt Messenger sandstones immediately southeast of the deeper producing Kapuni formation. The seismic anomaly is believed to represent an oil (or gas) bearing zone at about 1800m depth. If successful, the well could discover up to 11 million barrels of new oil reserves.

Shell and Todd also join forces for the Patea West-1 well in PEP 38737, which will be a deviated well drilled from the adjacent onshore licence PEP 38760 up to 1.5km offshore and into the promising large, shallow oil prospect known as Patea, which is believed to straddle three permits, PEP 38737, 760 and 719.

Oil has already flowed in tests of the shallow Manutahi sandstones in some of Swift Energy's Kauri wells in 38719 and the Patea West location is interpreted to be on the same structural closure, but updip of these wells.

Shell Todd Oil Services then plans to drill the onshore Patea East-1 well in PEP 38760, which Todd alone was awarded earlier this year. Todd Energy says the Patea prospect appears to be separated into eastern and western parts by a subsurface basement ridge and that Patea East-1 will test the eastern part of this structure.

The target zone is predicted at a depth of between 1000 and 1100m, with the prospect having the potential to hold some tens of millions of barrels of oil.

Finally, Tweedie said Todd Energy was conducting a major reservoir review of its McKee and Mangahewa fields, acquired from Shell New Zealand earlier this year, and anticipated increasing the level of recoverable reserves for both these onshore Taranaki fields.