Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available

The Triassic to Jurassic rocks of Clarence-Moreton Basin contain abundant oil-proneorganic matter of terrestrial origin particularly in the Walloon Coal Measures and to a lesserextent in the Koukandowie Formation. This is reflected in petrographic composition, pyrolysisyields, elemental composition and extractable hydrocarbon yields. Maturation levels vary fromimmature to marginally mature in the west to overmature in the eastern part of the basin inNSW. Calculations based on Rock Eval data show that significant oil generation occurred ina narrow maturation range (0.8-1.0% vitrinite reflectance) and that migration has been highlyefficient. Potential reservoirs are present in quartzose sandstones in the KoukandowieFormation, Gatton Sandstone, Ripley Road Sandstone and Raceview Formations. Maturation modelling and fission track analyses indicate that hydrocarbon generation occurred in theperiod 80-100 Ma during a period of high heat flow when the Tasman Sea spreading ridgewas adjacent to the southeastern side of the Logan Sub-basin. Despite the abundance ofoil-prone source rocks, the basin is considered to be largely gas-prone because the drainageareas for most larger structural traps are overmature. The main difficulty in exploration ispredicting the distribution of porosity and permeability which varies because of bothdepositional facies and diagenesis, even in quartzose units. The area with the greatest hydrocarbon prospectivity is the New South Wales part ofthe Logan Sub-basin which has gas potential throughout and a chance of minor oil discoveriesalong its western margin. The northern Logan Sub-basin has some prospectivity for oil andgas and the Laidley Sub-basin has minor prospectivity for oil in the Raceview Formation.

Petroleum source rocks are found at three levels in the Ordovician sectionin the Canning Basin and appear to be at similar stratigraphic levels and ofsimilar organic facies to the source rocks which have produced the gas andgas-condensate fields in the Amadeus Basin. In both basins shallowintersections in drillholes have yielded material at a low level of thermal maturity.Samples have shown that these immature source rocks contain algal-sourcedType 1 kerogens with a high hydrogen index and a large capacity to generate oil(eg Hoffmann et al., 1987). Deeper wells in both basins encountered sourcerocks at higher levels of maturity associated in some cases with oil fluorescenceand shows of live oil. By comparing the results of Rock-Eval pyrolysis analysisfor these more mature source rocks with those of the immature rocks the degreeof kerogen conversion to hydrocarbon (the Transformation Ratio of Espitalie eta)., 1986) can be estimated. The results from 14 wells along the BroomePlatform show a rapid downward increase in transformation ratio (TR) through theOrdovician section which can be correlated to the rapid downward increase in theconodont alteration index (CAI) previously documented by Nicoll & Gorter (1984).This correlation shows that the zone of peak oil generation lies between the endof CAI Zone 1 and the beginning of CAI Zone 2. The Ordovician in the Canning Basin is known mainly from intersectionsin 22 drillholes. It is thickest in two sub-basins: the Willara, bounded to the northby the Admiral Bay Fault, and a larger unnamed sub-basin (roughly coincidentwith the later Fitzroy Trough), bounded to the north by the Oscar Range-Pinnaclefault system. Both fault systems appear to have been active during thedeposition of the Ordovician. The best known source rocks occur along thesouthern side of the northern sub-basin; they appear to be poorly developed, orabsent, in the Willara Sub-basin. Overmature source beds are locally preservedin fault remnants under the Lennard Shelf and may exist at great depth in theFitzroy Trough.

Legacy product - no abstract available

Legacy product - no abstract available

REGIONAL DEEP SEISMIC of the NORTH WEST SHELF by the AGSO North West Shelf Study Group (J.B. Colwell,N.F. Exon, P.J. Hill, G.W. O'Brien, C.J. Pigram, D.C. Ramsay, H.M.J. Stagg, H.I.M. Stracktneyer, P.A. Symonds, J.B. Wilcox) PRE-JURASSIC RIFT ARCHITECTURE AND TECTONIC DEVELOPMENT, TIMOR SEA/ASHMORE CARTIER REGION by G.W. O'Brien, J.B. Wilcox, S. Baldwin, C.J. Pigram, M. Morsel & J. Ostby TECTONIC EVOLUTION OF THE BASS STRAIT REGION, AND ITS IMPLICATIONS FOR PETROLEUM POTENTIAL by J. B. Wilcox & J. Colwell THE OTWAY BASIN - A COMPLEX PASSIVE MARGIN IN SOUTHEASTERN AUSTRALIA by D. M. Finlayson, G. W. O'Brien and C. V. Reeves PHILIPPINE MARINE SEISMIC SURVEY PROJECT^10 by Chao-Shing Lee, Malcolm C. Galloway, Aidan Moore and Andrew Fraser DEEP WATER PETROLEUM PROSPECTS IN THE^12 LORD HOWE RISE REGION by P.A. Symonds & J.B. Wilcox EVOLUTION OF THE CANNING BASIN AND ITS PETROLEUM^14 SYSTEMS: PROGRESS REPORT by M. J. Jackson, J. Kennard, K.. Romine, P. Southgate, M. Sexton, R. Shaw, C. Foster, P. Jones, R. Nicoll, G. Young, I. Zeilinger

The breakup of Gondwana during the Mesozoic resulted in widespread basin formation along Australia's southern margin, of which the Bight Basin is a component. In contrast to many other extensional margins, the Australian southern margin has been classified as a non-volcanic rifted margin, despite the reported occurrence of scattered volcanic and intrusive rocks in the geological literature. Public release of the Flinders 2D seismic survey data in the Bight Basin has allowed the accurate mapping of widespread sills, dykes, lava flows and volcanoes.