ABSTRACT: The Offshore Canning Basin: A Hydrocarbon Misfit or an Early Developer on the North West Shelf?
PASSMORE, VIRGINIA L., Bureau of Mineral Resources, Canberra, Austrlian Capital Territory, Australia
The offshore part of the Canning basin forms part of the hydrocarbon rich North West Shelf of Australia. A comparison of the Canning with its neighboring basins suggest it is the "odd man out." It is the least explored of the North West Shelf basins. The Canning basin has onshore discoveries; offshore, there are recorded oil shows but no discoveries to date. It lacks the outer margin horst blocks and submerged plateau that characterize the adjacent basins, and has few of their central basin Mesozoic horsts and grabens. The basin's northwesterly Paleozoic structural grain rather than the Mesozoic northeasterly structures associated with the breakup of Gondwana predominate overmost of the present Canning shelf area. Faulting that formed the main hydrocarbon structure traps took place in the Late Paleozoic, Triassic, and Early Jurassic in the Canning basin rather than in the Triassic, Jurassic, and Cretaceous or later age of the neighboring basins. Late Triassic and Early Cretaceous reef complexes form stratigraphic traps in the Canning's western margin. Lower Carboniferous, Triassic, and some Lower Jurassic source rocks are presently within the basin's oil window, but the Upper Jurassic and Cretaceous sequences that source the adjacent basins are immature in the Canning basin.
The lack in the Canning basin of similar age structure, source, and reservoir found in the other North West Shelf basins does not equate to a lack of petroleum potential in the Canning. Hydrocarbon potential appears to have developed earlier in the Canning basin. Source, seal, reservoir and structure are all present -- they are just in older rocks.
AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)