Abstract 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 km 2 ) 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 Culf 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.

Abstract The Northwest Shelf of Australia is herein considered to be the part of the continental margin of Western Australia extending south westward to approximately lat. 22 °S and northeastward to approximately long. 131 °E (Figure 1). It was formed by a series of major tectonic episodes that began in the late Paleozoic and continued into the Cretaceous, and that resulted in the complete breakup of eastern Gondwana and the formation of the Indian Ocean. Woodside Offshore Petroleum and its related predecessors have been Operator for the Northwest Shelf Joint Venture Group during more than 20 years of exploration in the region. Initially, the Group held exploration permits covering parts of all four basins of the Northwest Shelf, though these have now been substantially reduced. Most of the Joint Venture’s work has been centered on the Dampier area of the offshore northern Carnarvon basin, for which reason this chapter concentrates on the Barrow-Dampier subbasin. Discussion of the Beagle subbasin is included with that on the Barrow-Dampier subbasin because those two adjoining subbasins are similar in style. This is followed by a brief review of the Browse basin, in which the Joint Venture has also been active. Only four wells have been drilled by the Joint Venture in the offshore Canning basin, the last one in 1971, and few wells have been drilled there by other operators. Warris (1973) summarized the geology and exploration history of the offshore Canning basin, and since then virtually no new work has been done in

Abstract The Carnarvon Basin is an epicratonic, faulted and folded Phanerozoic basin that encompasses more than 1000 km (621 mi) of the west and northwest coast of Western Australia (Figure 12 ).