It is Carnarvon's third discovery in a row in Western Australia, following Phoenix South-1 and Roc-1.

While warning that it could take months to report on the final results of the well, Carnarvon boss Adrian Cook said this morning that early interpretation of fluorescence data indicates the well has discovered the presence of hydrocarbons in the target interval.

The JV elected not to complete the full suite of logging activities, believing sufficient information has been acquired.

Some 91m of core has been recovered from the well, which was drilled within WA-155-P(1), and the core is being transported to shore for evaluation at laboratories in Perth, to help the partners determine the extent and quality of the net reservoir and estimate the oil-in-place and recoverable volumes in the Outtrim and Outtrim East structures.

The well was drilled to a total depth of 1441m targeting oil in Pyrenees Member where oil discovered in Outtrim-1 plus secondary targets in the Birdrong Sandstone and Mardie Greensand, where oil discovered in Corowa field some 12km to the north-east.

Outtrim is also close to the Blencathra-1A oil discovery, which like Outtrim-1 was considered too small to be developed alone, but could be combined to develop a new production hub.

The undeveloped Corowa field, owned by the under-administration Hydra Energy, is also within tie-back distance.

Carnarvon says the aim of entering WA-155-P(1) was to discover and aggregate several sufficient small oil resources to underpin a central field development.

The partners need to prove up around 20 million barrels to support an oil development.

The partners have not provided any details about the discovery.

The Tom Prosser jack-up rig will now be released from the well, and after a brief respite will drill the Driftwood-1 exploration well for Quadrant (40.665%), OMV (39.557%), JX Nippon (10%) and Tap Oil (9.778%).

Roc-2

Elsewhere, Quadrant has completed drilling of the Novara-4H development well within WA-35-L and the Ocean Monarch semi-submersible has started spinning the drillbit on the much-anticipated Roc-2 appraisal well in the Bedout Sub-basin.

The well is being drilled up-dip of the Roc-1 gas- condensate discovery to appraise the Caley section and prove up a resource above the minimum economic field size and to establish potential flow rates for future development planning.

The well will also assess the deeper potential of the Milne member, where encouraging hydrocarbon shows were observed during the final phase of drilling the Roc-1 well, and the shallower Huxley member, where oil shows were encountered at Roc-1.

Roc-2 will be drilled in around 100m water depth to a planned total depth of around 5250m.

The partners, Quadrant (80%) and Carnarvon (20%), aim to cut 120m of core before undertaking the first flow testing in the wider Roebuck Basin in decades.

The Ocean Monarch is expected to be on location until October.