And while the results may be smaller than some market watchers expected, they are over just a small area of the sub-basin.
Carnarvon appointed US-based DeGolyer and MacNaughton to assess the potential recoverable oil within the Phoenix 3D seismic area, based on data provided by operator Apache Energy.
The oiler says the Phoenix South structure contains the potential for between 6-56 million barrels, with a best estimate of 19 MMbbl of contingent resources, not exactly the barnstormer the joint venture may have hoped for, but still an interesting new target in the offshore areas Western Australia, and a bonus given the well was originally drilled to assess a gas prospect.
DeGolyer and MacNaughton also verified Apache's initial oil-in-place estimate of up to 300MMbbl for the Phoenix South structure, assessing 296 MMbbl OIP in the Lower Keraudren Formation.
Apache's contingent and prospective recoverable oil assessed in the entire Phoenix 3D study area are for between 48-232 MMbbl (gross) with a best estimate of 104MMbbl.
The Roc prospect, the next structure to be drilled later this year, has recoverable potential of between 12-133 MMbbl, with a best estimate of 42MMbbl, classed as prospective resource.
"In the context of recent Australian oil discoveries, these estimates of recoverable oil within the
Phoenix South and nearby structures are significant and great news in terms of our strategy of opening up an entirely new oil province on the North West Shelf," Carnarvon managing director Adrian Cook explained.
He said the partners were still in the earliest stages of understanding what was uncovered in the previously ignored Triassic fairway, which explains why there is such a high level of uncertainty.
The ongoing technical work, including further core analysis by Apache, is expected to refine the range and provide some indication of recovery potential.
Cook described Roc-1 as a "standout exploration opportunity" with a 42% chance of success and a prospective resource that is commercially attractive.
Other targets, such as Bewdy and Bottler, have best estimates of 7-9MMbbl, and a POS of 42%.
"A high-side outcome of up to 133MMbbl of recoverable oil would be an outstanding result and there is little capital risk to investors as the first $US14 million [$A18.3 million] of Carnarvon's share of any drilling activity in the permit will be paid for by Apache and JX Nippon."
The Apache-led JV continues its work on the Phoenix South-1 well data and the data from previously drilled wells in the permit in a bid to better reservoir development and quality, the type and potential source of the oils discovered and determining where the same results may occur elsewhere in the blocks.
Cook said the work was slow going, given the wildcat nature of the discovery, and that there was no firm timetable for completion of volume estimates.
Apache has 40% of WA-435-P and WA-437-P, while Carnarvon, Finder Exploration and JX Nippon have 20% each.
Carnavon shares were up 4% this morning in early trade at $0.125.
