The North West Margin Transects Cruise is part of a program being undertaken by AGSO to determine the structural architecture of the north-western margin of Australia and the influence of structuring on the location, migration and trapping ofhydrocarbons in the region. An important aspect of this program is the acquisition ofa series of full margin 'dip' transects extending from unrifted cratonic basement tobeyond the continent-ocean boundary, and at least two 'strike' transects that willextend along the full length of the shelf from the eastern Timor Sea to North WestCape. The major objective of the proposed cruise is to extend previous AGSO deepseismic surveys across the Browse (Survey 119), offshore Canning (SNOWS-3/Survey 120) and northern Carnarvon Basins (SNOWS-/Survey 101, SNOWS-2/Survey 110) to complete these margin transects. Specific objectives of theproposed survey are: *Determine the regional structural framework of the Scott Plateau area and itsrelationship to adjacent features such as the Argo Abyssal Plain, the BrowseBasin and the Rowley Sub-Basin of the offshore Canning Basin; *Determine the regional structural framework of the Exmouth Plateau and itsrelationship to adjacent features such as the Barrow-Dampier Sub-basin, and theArgo and Gascoyne Abyssal Plains. *Define the broad deep-crustal structure of the region and develop a modelexplaining the tectonic, subsidence and thermal history of the Scott Plateau andthe Exmouth Plateau in relation to the development of the continental margin andadjacent ocean basins. *Assess the effects of the deep crustal structures and their reactivation phases onthe development of known petroleum accumulations. To address these objectives it is proposed that RV Rig Seismic be used to acquireabout 3276 km of deep crustal (16 second record length) multichannel seismic andother geophysical data along 9 transects across the outer margins of the Browse,offshore Canning and northern Carnarvon Basins. The survey will tie into the 1991SNOWS-1 (101), 1992 SNOWS-2 (110), 1993 Browse Basin (119) and SNOWS-3(120) surveys.

The 50 major Australian source rock units can be grouped according to age into 15 intervals comprising Late Neoproterozoic, Middle Early Ordovician, late Early Ordovician, Middle to Late Devonian, Early Carboniferous, Early to early Late Permian, late Late Permian, Early to Middle Triassic, Early to Middle Jurassic, Middle to Late Jurassic, Late Jurassic, latest Jurassic to Early Cretaceous, Early Cretaceous, Late Cretaceous, latest Cretaceous to Eocene. Only marine source rocks are known older than Permian, while both marine and nonmarine source rocks are known from Permian and younger intervals. As expected, the marine source rocks are more common where there is a greater degree of continental inundation, while nonmarine source rocks are present only when the continent was at higher palaeolatitudes and when there was at least a moderate amount of continental inundation.

Subsidence and thermal history analysis of 24 wells and seismic-defined depocentre sites has been undertaken to investigate the generation and expulsion history of the Early Carboniferous and Permian petroleum systems in the Petrel Sub-basin. Modelled oil and gas expulsion from postulated oil-prone source units within the Lower Carboniferous Milligans Formation is restricted to two offshore depocentres immediately north and south of the Turtle-Barnett High. Expulsion commenced in the Late Carboniferous, reached its peak in the Early Permian, and minor expulsion continued throughout the Permian and Early-Mid Triassic prior to the onset of regional uplift associated with the Late Triassic Fitzroy Movement. Limited gas expulsion is also modelled in the onshore Carlton Sub-basin, and although this unit is sufficiently mature in this area to have generated oil, the models suggest that generated volumes are insufficient for expulsion of oil. Modelled oil and gas expulsion from mudstones and coaly mudstones of the Lower Permian Keyling Formation is restricted to the central and outer portions of the Petrel Deep. Expulsion from the outer Petrel Deep occurred in the Late Permian - Early Triassic, and expulsion from the central Petrel Deep commenced and peaked in the Early Triassic, with subsequent phases of minor expulsion in the Late Triassic - Cretaceous. Oil expelled from these source units may have migrated to pre-Fitzroy Movement structures and stratigraphic traps within and on the flanks of the Petrel Deep, but to date the only possible indication of such an oil charge are low confidence SAR slick anomalies east and southeast of the Petrel Field. Modelled gas expulsion from the Upper Permian Hyland Bay Formation is limited to the outboard limits of the Petrel Sub-basin, and occurred in the Jurassic-Cretaceous with peak expulsion in the mid-late Cretaceous. This unit is considered too lean to expel significant quantities of oil. These expulsion models are integrated with the known distribution of hydrocarbon accumulations, shows and SAR anomalies to map the extent of the petroleum systems in the Petrel Sub-basin. These maps can then be used to assess the likely source(s) of the recent Blacktip-1 gas discovery, and to evaluate the charge potential of traps within the sub-basin, including those within the 2002 offshore acreage release areas.

Legacy product - no abstract available

The offshore Gippsland Basin is Australia's major producing hydrocarbon province. Acreage has historically been tightly held, and opportunities for new players in this highly prospective basin have been limited. However, recent relinquishments have allowed the Australian Federal and Victorian State Governments to offer three potential permits to petroleum exploration companies and consortia. The Bureau of Mineral Resources Petroleum Group, in collaboration with the Victorian Department of Manufacturing and Industry Development's Petroleum Branch, has produced a hydrocarbon prospectivity package for the Southeast Gippsland Basin, with particular emphasis on the three areas to be released. The package takes the form of this BMR Record 1991/9. The Package covers regional geology, geophysics, palaeogeography, and hydrocarbon play concepts, together with a new structural interpretation for the Gippsland Basin developed at BMR. In addition, for each release area the package covers previous exploration, local geology and play concepts, reservoir geology and engineering, and geohistory. Prospects and leads are described in detail, and the text is complemented by some 80 Plates and Figures.

Processed seismic data (SEG-Y format) and TIFF images for the 2007 Isa-Georgetown Deep Crustal Seismic Survey (L184), acquired by Geoscience Australia (GA) under the Onshore Energy Security Program (OESP), in collaboration with the Queensland Geological Survey. Stack and migrated images and data are included for lines 07GA-IG1 and 07GA-IG2 as well as CDP coordinates and maps. Raw data for this survey are available on request from clientservices@ga.gov.au

Processed seismic data (SEG-Y format) and TIFF images for the Arrowie line acquired as part of the 2008 Curnamona-Gawler-Arrowie Deep Crustal Seismic Survey (L189), acquired by Geoscience Australia (GA) under the Onshore Energy Security Program (OESP). Stack and migrated data for line 08GA-A1 as well as CDP coordinates and gravity data. The Arrrowie line is 60km in length and was sited south of Lake Torrens and north of Port Augusta. Raw data for this survey are available on request from clientservices@ga.gov.au

2002 and 2003 may well prove to be pivotal years for petroleum exploration in Australia as we endeavour to meet our twin imperatives of finding more oil and using gas. Long term gas supply contracts have been signed with China and a number of key oil discoveries have been made both on and offshore. Deep water wells will be drilled that have the potential to usher in another phase of major oil discovery akin to bonanza of the 1960s, when the first steps into the offshore resulted in billion barrel discoveries in Bass Strait. By the close of the first successful cycle of exploration in Australia (1960 to 1972) all currently producing basins were identified as petroliferous, the major play types had been established and over 60% of Australia?s current oil reserves found. The key drivers of this phase were the access to new basins opened up by the move to offshore exploration and the stimulus to further exploration provided by discovery success. The same drivers are apparent now. Recent discoveries in the Perth, Carnarvon, Otway and Browse basins provide strong indications that a significant new cycle of exploration success is already underway. In many cases these finds represent the largest fields yet found in the basin or at least the largest in the last thirty years. The usual discovery history trend of declining field sizes over time has been turned on its head - clearly demonstrating that many of Australia?s currently producing basins still have a long way to run and encouraging further exploration efforts. Perhaps of even more importance to Australia?s long term liquids self sufficiency is the current deepwater drilling campaign which is stepping out beyond former geographic limits. The first wells in major Mesozoic depocentres on the outer margin of the North west Shelf and in the Great Australian Bight are being drilled with the potential to establish entirely new petroleum provinces.

The extreme variation in the natural endowment of petroleum resources between regions has been a key geo-political driver in the last century and may well remain so in the decades ahead. Most of the world?s oil is located in a latitudinal belt lying predominantly north of the equator, running from the Gulf of Mexico and Venezuela, to North Africa, through the Middle East, the Caspian and Central Asia and down to Indonesia. Klemme and Ulmishek (1991) calculated that this Tethyan Petroleum Province contained 68% of global original petroleum reserves. Its vast petroleum resources were derived largely from the organic rich marine rocks deposited in low latitude in restricted basins and on shallow carbonate shelves flanking the various Palaeozoic, Mesozoic and Cainozoic incarnations of the east-west orientated Tethys Ocean.

Conference volume and CD are available through the Petroleum Exploration Society of Australia