The company said wireline logs indicated the presence of gas throughout the relatively low-permeability sandstone interval in the primary Brewster Sandstone while pressure data acquired within the reservoir supported the potential for the gas column to extend below the base of the sand.

The company also said the reservoir penetrated in the well is within the same geologic formation that is gas-bearing in nearby fields such as Ichthys, Mimia and Prelude.

Santos vice president exploration Trevor Brown said it was pleasing to make a discovery in a basin with so many developments under consideration.

"Further work will now be done on recovered samples to understand the reservoir characteristics and an appraisal plan will be developed to define the size of the resource."

Santos started drilling the well, which targeted a large stratigraphic prospect near Ichthys, in June but had to sidetrack it due to mechanical issues.

The well is less than 50km southwest of Ichthys and is targeting the gas potential of the lower Cretaceous sands.

Santos has said Burnside-1ST1 has an upside resource potential of 100-500 million barrels of oil equivalent.

The well, in WA-281-P, was drilled with the Songa Mercur semi-submersible drilling rig to a depth of 4182m.

Santos is operator and holds 47.38% of WA-281-P. Chevron has a 24.83% stake, Inpex has 20% and Beach Petroleum holds the remaining 7.34%.