Origin said yesterday afternoon that the jack-up Ensco Rig 107 had penetrated the primary Farewell Formation reservoir target at a depth of 2896m and had encountered good gas shows.

The company added that while the presence of gas shows was encouraging, it was not possible to comment on their commercial significance until the rig had drilled through the entire reservoir and logs acquired over this section.

Momoho is being drilled about 6km southeast of the Kupe production facilities to a planned total depth of 3142m and sits between two exploration wells drilled about 20 years ago - Kupe South-4, a sub-commercial gas-condensate discovery, and Kupe South-5, which flowed sub-commercial quantities of oil and some gas.

Minority Kupe partner New Zealand Oil & Gas has said it expects the Momoho prospect to contain estimated total recoverable reserves of about 200 billion cubic feet equivalent of gas in both gas and liquids.

The potential to tie back future near-field discoveries has been incorporated into the Kupe development infrastructure.

The Kupe partners are operator Origin Energy (50%), Genesis Energy (31%), New Zealand Oil & Gas (15%), and Mitsui E&P NZ (4%).