Any or all of Blocks 97-A, B and C, located in the Eromanga Basin of South Australia, are available for application for Petroleum Exploration Licences until 15 October 1997 at 4 p.m. Licences will be offered on the basis of the most competitive work program. Completed application forms (enclosed with this offer document) should be accompanied by a proposed five year work program, a map of the area applied for, a $2 000 application fee and details of the technical and financial resources of the applicant. The blocks on offer overlie prospective sediments of four superimposed intracratonic basins separated by unconformities - the Cambro-Ordovician Warburton Basin, the Permo-Carboniferous Pedirka Basin, the Triassic Simpson Basin, and the Jurassic-Cretaceous Eromanga Basin. The Eromanga Basin is in turn, covered by the Cainozoic Lake Eyre Basin. The three blocks together occupy the entire South Australian portion of the Pedirka Basin east of the Dalhousie-McDills Ridge. The Pedirka and Simpson basins are separated from the Permo-Triassic Cooper Basin by the Birdsville Track Ridge, a complex structural high that formed during the Devonian to Carboniferous in response to the Alice Springs Orogeny. The Cooper Basin is Australia's largest and most important onshore gas and oil province, and significant volumes of oil are being produced from the overlying Eromanga Basin sequence. Although the depositional and structural histories of the Cooper/Eromanga and Pedirka/Eromanga depocentres are similar, exploration in the Pedirka Basin region has been sparse. Only seven petroleum exploration wells have been drilled within the 20 356 square km area occupied by the three offered blocks, and only three of these wells are considered valid structural tests. One of the three wells encountered drilling problems and did not evaluate the Permian (Pedirka Basin) sequence. Seismic coverage is limited with large areas within each of the three blocks not being covered by modern seismic. An approximately 2.5 km spacing of 1980 to 1985 seismic data in a dip direction and 5 km spacing in a strike direction across local areas, provides the most comprehensive seismic grid in the area. Oil accumulations that have been discovered in the Eromanga Basin are commonly in the order of about five million barrels in-place, and the existing seismic grid is far too coarse to locate reserves of this magnitude. Fair to excellent quality sandstone reservoirs sealed by siltstone and shale units are present within the Pedirka, Simpson and Eromanga Basin sequences. Both oil and gas prone, organically rich source rocks are present within the Triassic Peera Peera Formation and the Jurassic Poolowanna Formation. Mainly gas prone source coals and shales are present in the Permian Purni Formation. Nine prospects, 16 strong leads and 19 weak leads are identified within the three blocks and given the current paucity of seismic data in the region, it is certain that numerous additional structures will be found with future seismic acquisition. Most of the structures identified to date access large hydrocarbon drainage areas. There is also considerable stratigraphic trapping potential within the release area with the two Triassic formations, the upper Permian formation and the lowermost Jurassic formation pinching out on the western flank of the basin, and the eastern edge of the Pedirka Basin sequence being more or less coincident with the eastern boundaries of ER97-B and C.