The Woodside-Burmah Group had drilled 45 wells, totaling 469,692 ft (143,155 m), in this remote offshore region to the end of 1973. Ten of the 37 wildcat wells discovered new fields, and all 8 appraisal wells were successful. Permit areas total 140,000 sq mi (360,000 km²) and water depths are from 150 to 6,000 ft (46-1,830 m).

Major tectonic elements include three essentially onshore Proterozoic cratons separated by the Canning and Bonaparte Gulf sedimentary basins. The sedimentary basins cover both onshore and offshore areas. Other major depocenters--the Dampier and Beagle subbasins and the Browse basin--lie entirely offshore from the cratonic blocks. All five offshore basins are filled with thick Mesozoic to recent sediments. The basins probably formed as a result of continental rifting initiated during Permian time. Many of the basins are subdivided as a result of major block-faulting movements which occurred from Late Triassic to Middle Jurassic time.

Permian and pre-Permian strata have been penetrated in only a few places. Thick marine Early Triassic shales are succeeded by later Triassic to Middle Jurassic fluviodeltaic units. Late Jurassic to Early Cretaceous transgressive marine shales and sandstones cover an irregular block-faulted paleotopography in the Dampier and Beagle subbasins, forming important structural-stratigraphic traps. Early Late Cretaceous fine clastic units grade through later Cretaceous to early Tertiary marlstones and calcilutites to coarse-grained carbonate rocks in the post-Oligocene section. Several Cretaceous and Tertiary unconformities are present.

Recoverable gas reserves found in the Dampier subbasin to date total approximately 18 Tcf. About 13.5 Tcf of the reserves are in the proved and probable categories; the giant North Rankin field alone contains 7.9 Tcf. Another potentially large gas-condensate discovery has been made in the Browse basin.