A state-of-the-art drill rig from Germany is helping extend the life of New Zealand's oldest offshore natural gas field.
In its heyday, the Maui field off Taranaki produced 90% of New Zealand's gas needs, but that has now fallen to 20% and the field is unlikely to last beyond another decade.
The Archers Emerald rig is reaching difficult-to-access pockets of gas 4km under the sea by drilling down through an existing well and branching off horizontally.
Shell Todd Oil Services general manager Rob Jager says the drilling project is costing up to $100 million.
He says if more gas is found, it could add up to 18 months of gas production.
Shell Todd is also planning to drill several exploration wells on the edge of the Maui field.