Drilling at the well confirmed a gross gas and condensate zone of 18m (with no water indicated) in the Elevala sandstone by January 4, while in the following week the subsequent sidetrack was drilled 650m northeast and penetrated the secondary target of the Toro sandstone.
"Logging while drilling, sampling and pressure measurements have defined a gas-water-contact to the hydrocarbon accumulation, successfully fulfilling the primary objective of the sidetrack well," Horizon said.
"This establishes a field gas column height of greater than 50m and further implies that the Elevala structure is full to spill point."
The sidetrack will be plugged and suspended while plans are underway to mobilise the rig to the Ketu-2 appraisal well in the same licence (PRL 21).
In the meantime, new seismic is already being shot over the Elevala, Tingu and Ketu structures and this data will be analysed before resource volumes are revised.
Kina Petroleum managing director Richard Schroder said the new seismic should increase the total resource estimate for the block, "further improving the chance of commercialising the condensate/liquids trapped within in PRL 21".
Horizon chief executive officer Brent Emmett said the Elevala-2 drilling was a good result on a number of fronts.
"Firstly, subject to the new seismic confirming the current map of the Elevala structure, we have a new, potentially commercial, project to evaluate, containing material gas and condensate volumes.
"Secondly, the likelihood that Elevala is full to spill increases the chances of Ketu [appraisal well] also being full, given that it lies between Elevala and the probable hydrocarbon ‘kitchen area to the north."
Emmett said the well also significantly upgraded its Tingu prospect to the northwest and another lead to the west.
Before drilling, Horizon advised of certified mean recoverable contingent resources of 302 billion cubic feet of gas and 19.3 million barrels of condensate.
"Based on the drilling results and the existing seismic data, the well outcome is to the high side of expectations," Horizon said.
The Elevala-1 well was discovered in 1989-1990 and flowed at a rate of 11.9 million cubic feet of gas and 634 barrels of 54-degree API condensate per day in a test.
PRL 21, located in PNG's Western Province, is owned by Horizon (45%), Talisman Energy (40%) and Kina Petroleum (15%).