Oil and gas major Santos on Thursday announced that the Dorado-2 appraisal well had confirmed a “major” oil and gas resource in the Bedout basin, offshore Western Australia.
The well was drilled down-dip about 2 km from the Dorado-1 discovery of July last year, and encountered 85 m of net reservoir in the primary Caley formation.
Santos MD and CEO Kevin Gallagher said the Dorado-2 appraisal well showed that the Dorado discovery was larger than anticipated. “The value of the discovery is greatly enhanced by the high-quality reservoirs and fluids and the shallow-water setting, which should facilitate a cost-competitive development.”
The company said that an oil-water contact was intersected at 4 003 m measured depth, with 40 m of net oil pay encountered. An additional 11 m of pay was encountered in the Upper Caley sands. Preliminary wellsite analysis indicated the upper zone was oil-bearing, but it remained subject to further analysis to confirm the hydrocarbon phase.
A further 32 m of net pay was encountered in the underlying Baxter and Milne sandstones, with no fluid contacts intersected. Both sands were interpreted to be gas bearing, although similar to the Upper Caley, the Milne hydrocarbons would require further analysis to confirm the hydrocarbon phase, Santos said.
Wireline pressure testing had confirmed that all the reservoirs were in pressure communication with the equivalent intervals in Dorado-1, mitigating one of the key pre-drill risks to a future development. Hydrocarbons have also been recovered from each reservoir interval through wireline sampling.
Initial indications were that fluid compositions were similar to the light oils and gases that were sampled in Dorado-1, where condensate yields ranged from 190-barrels to 245-barrels per million standard cubic feet in the Upper Caley, Crespin and Milne Formations, and from 70-barrels to 90-barrels per million standard cubic feet in the Baxter Formation.
“Dorado opens a new basin with high prospectivity in permits where Santos has a high equity position and rich exploration inventory with potential to substantially grow the resource base,” said Gallagher.
Dorado-2 is located in petroleum permit WA-437-P (Santos 80% and operator, Carnarvon Petroleum 20%). It is in commonwealth waters about 160 km north of Port Hedland.