ABSTRACT: The Petroleum Potential of the Officer Basin
LINDSAY, JOHN F., and JAMES LEVEN, Bureau of Mineral Resources, Canberra, Australian Capital Territory, and GRAHAM KRIEG and DAVID COCKSHELL, South Australian Department of Mines, Adelaide, South Australia, Australia
The Officer basin is a remote intracratonic basin, which is poorly exposed because of widespread Pleistocene sand-dune and Tertiary limestone cover. Its hydrocarbon prospectivity has been perceived to be relatively limited and in combination with access and logistic problems, the basin has been seen as a high risk prospect but this conclusion needs reappraisal.
Preliminary studies suggest that the basin is a complex, polyphase, stacked basin formed in response to major extensional events that occurred during the-breakup of a supercontinent in the late Proterozoic and early Paleozoic. These events resulted in the initiation of a number of intracratonic basins across Australia, including the Amadeus basin from which there is hydrocarbon production.
Oil shows from a number of exploration wells in the eastern Officer basin have demonstrated in situ oil generation from alkaline playa deposits in the Cambrian Observatory Hill Formation. The Neoproterozoic Rodda beds have relatively low overall TOC measurements, but recent studies indicate the presence of algal mats with excellent source potential. Even with low TOC, the volume of this unit, which has a thickness of greater than 3000 m, suggests it could be a productive source.
Possible reservoirs include the basal Cambrian Relief Sandstone and the Neoproterozoic Murnaroo Formation, both of which have porosities up to 20%, but neither of which has been tested within closure. Intraformational red bed, evaporitic and carbonate units provide seals. Potential plays include salt swells, pillows and walls, related anticlinal doming, and faulting associated with the Late Paleozoic Alice Springs orogeny.
AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)