Initially the well was targeting a potential 1.5 million barrel resource but the companies have now announced that preliminary oil in place is estimated to be between 8.5 million and 12.3 million barrels of oil. Preliminary Proven & Probable (2P) recoverable reserves for the field are estimated to be 3.4 million barrels.

These early estimates are factored on three of the four commercial intersections, as further studies are still needed to assess the potential of the Patchawarra Formation.

Whilst DST # 4 over the Patchawarra Formation flowed gas there is a significant chance that the gas is contained in a small cap sitting on top of an oil zone. The companies said the key issue was to determine the proportion of gas and oil contained in the reservoir.

"The significance of this discovery to a company the size of Cooper, is that, fully developed, Worrior-1 will provide us with enough free cash flow to self fund all future exploration in the area," said Cooper chief executive Greg Hancock.

"Importantly this estimate could be conservative as we have not included any potential reserves from the lower Patchawarra zone, but we believe oil will ultimately be recovered from this sand as well," he said.

Work will now focus on preparing the well for an extended production test (EPT) in November to run for at least six months with an offtake rate of 1200 barrels of oil per day, which will be trucked into Santos's Moomba facility. Construction of permanent facilities would commence in early 2004.

Worrior-1 intersected a total of 35.5m of net hydrocarbon pay in four horizons the McKinlay, Birkhead, Hutton and along with the potentially commercial accumulation in the Patchawarra.

A study will immediately commence for the laying of a pipeline to access the oil pipeline grid system in the Cooper Basin. A pipeline would be expected to at least double the present planned offtake of 1,200 bopd from Worrior-1.

Participants in the PEL 93 Joint Venture are Stuart Petroleum (operator) 70% and Cooper Energy NL 30%.