A failure in the liner hanger assembly at about 4000m while cementing seven-inch liner into place in Cardiff-2 means the lower section of the hole is no longer accessible.

The joint venture participants have now agreed to deviate a Cardiff-2A well out of the present wellbore. Cardiff-2A will deviate from the existing wellbore near the 3,000m (depth level and be drilled as a vertical well to a target depth near 4,850m (16,000 feet).

The deviation well is expected to provide an intersection of the Kapuni Formation in Cardiff-2A offset approximately 175m from the Cardiff-2 intersection, and in a similar geological setting on the Cardiff structure.

The Cardiff-2A operation is scheduled to take about six weeks from present in order to case off the Kapuni Formation in preparation for production testing.

"The joint venture participants were unanimous and prompt in their approval of this course of action, which reflects the promising results obtained from electric logging in Cardiff-2 as previously advised," said operator Austral Pacific in a statement.

Meanwhile at the nearby Cheal-A production site, jet pump production test operations on Cheal-A4 and Cheal-A3X are scheduled to commence within a few days.

Austral said it would have to pay its 25.1% share of the costs associated with the sidetrack. It had previously been “free carried” by partner Genesis Energy, which had funded the well to the tune of NZ$15 million in exchange for the rights to all gas accessed from the Eocene-aged Kapuni from this well.