PROGRESS OF STUDIES, BASIN STUDY GROUP, BUREAU OF MINERAL RESOURCES

Abstract

The Basins Study Group is part of the Subsurface Section of the Bureau's Petroleum Exploration Branch and was formed in 1962 to collect and review available basic data on the sedimentary basins of Australia and Papua-New Guinea. The Core and Cuttings Laboratory forms the second part of the Subsurface Section, and the Laboratory's technical staff contribute to basin reviews by carrying out analyses of various kinds, and assist in the collection of data principally by providing thin sections of various sedimentary formations.

Recent activities of the Basins Study Group include a review of the Sydney Basin, and an increased effort to assemble basic data on all sedimentary basins, with particular emphasis on the Canning and Carnarvon Basins.

The review of the Sydney Basin is nearing completion. It was undertaken with the co-operation of the Geological Survey of New South Wales and received generous support from petroleum exploration companies active in the Basin. The review included detailed petrological examination of twelve wells and selected outcrop samples. The results confirmed the previously-held opinions that the reservoir characteristics of Sydney Basin sediments are generally unfavourable. At present there are no indications of untested onshore areas where an improvement in reservoir properties may occur. The Bureau petrologists detected the rare mineral dawsonite in eight wells; the mineral occurred mostly in Permian sediments, both in marine and non-marine rocks, but it was recorded also from Triassic rocks in the Kurrajong Heights No. 1 well. The review of geophysical data from the Sydney Basin was concentrated mainly on seismic work. The magnetic tapes of three surveys were replayed and considerable improvement in records was effected. Record sections of all seismic surveys were reduced photographically to a horizontal scale of 1:50,000 and the reductions were spliced to provide easily-managed cross-sections. The geophysical review is nearing completion and structure contour maps and isochrons are in preparation.

The collection of basic data is done for each sedimentary basin as it becomes available, but present emphasis is on assembling data from Western Australian basins: all seismic traverses in the onshore parts of the Canning and Carnarvon Basins have been plotted at 1:250,000 scale, and with the co-operation of the Geological Survey of Western Australia, bibliographies of the Canning, Carnarvon and Perth Basins have been compiled for issue as Open-file Records. Bibliographies of the Papuan and Ipswich-Clarence Basins have also been compiled.