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The Bass basin is the sister basin to the Gippsland. Both are extensional basins in southeast Australia between Tasmania and the mainland, and both occupy areas in excess of 60,000 km2. The Bass and Gippsland basins were resurveyed seismically by the Bureau of Mineral Resources to provide regional correlation and to penetrate seismic energy barriers caused by Eocene coals.
Analyses of these recent good quality deep seismic data, existing seismic data, and well information including thermal maturity, source rock richness, porosity, and permeability suggest that the Bass basin is not fully analogous to the Gippsland basin. Though stratigraphy is similar, there is a paucity of significant secondary faulting in Bass basin to act as paths for migration of hydrocarbons to thermally immature levels, as is the case in the Gippsland basin. Consequently, in spite of minor oil and gas in the thermally immature section, the hydrocarbon potential of Bass basin could be substantially limited to thermally mature levels.
Reservoir, seal, and source appear to be present in the Bass at thermally mature but rarely drilled levels within the deeper lower Tertiary and Upper Cretaceous lower Eastern View coal measures and in the rifted Lower Cretaceous Otway Group. Hydrocarbon leads at these levels are predicted from structural analysis, with synsedimentary transverse faults that developed during the extensional phase of the basin providing an important trapping component. Such leads are defined at drillable depths by seismic mapping. The Bass basin could thus ultimately emerge as a deeper hydrocarbon province.
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