Earlier this month, Auckland-headquartered Greymouth subsidiary Bonus Drilling brought the big rig to Taranaki from Taupo where it had been stacked for a year or so after doing some geothermal work for a private company, believed to be Geotherm Drilling Services, which subsequently went into receivership.

The rig, now renamed Bonus Drilling Rig #3, is at Greymouth’s Turangi production station site, overhauled and rigged up, with Bonus Drilling ready to spud the first of two appraisal wells in the gas-condensate field.

Greymouth chief operating officer John Sturgess said the rig was a welcome addition to the Bonus stable as Greymouth looked to an active year of onshore exploration.

Sturgess said more wells at Turangi would be necessary, though he declined to comment further on Greymouth’s 2008 exploration program.

“We will need to drill again at Turangi, to have increased security of supply to our customers who are taking increasing amounts of Turangi spot gas,” Sturgess said.

However, it is known two wells are included in Greymouth’s current program to appraise Turangi. The company discovered the field in mid-2006 and has since estimated 2P (proved and probable) reserves of 144 petajoules of gas and 4.8 million barrels of associated condensate.

Turangi is the country's third-largest onshore gas discovery behind the Kapuni and McKee fields.

Greymouth set up Bonus Drilling several years ago with a small, specially constructed rig – originally nicknamed the Orange Toughy but now known as Bonus Drilling Rig #1 – that is mostly used for well workovers.

Then, in August 2006, it imported the former Nabors International Drilling Rig 647 from Western Australia's Barrow Island to Taranaki where the rig, now known as Bonus Drilling Rig #2, has drilled several wells, including the commercial Moturoa-5, 6 and 7 wells at the historic Moturoa oil field at Port Taranaki, New Plymouth.