The well is currently running approximately 20 days behind schedule due to slower than expected drilling rates through the complex overthrust geology.

NZOG said progress had been slow because the rocks were hard and relatively unfractured, which they said was consistent with their predictions of an effective seal above the targeted structure.

A range of equipment configurations and drilling parameters was being trialled to improve drilling rate. A report from the company said they expected to intersect the target horizon by late June or early July.