| SYDNEY BASIN | ||
|---|---|---|
| State(s) | New South Wales | |
| Area (km2) | Offshore | 28,000 |
| Onshore | 36,000 | |
| Maximum thickness (m) | > 6000 | |
| Age Range | Permian-Triassic (Jurassic and Cretaceous section believed to have existed but now eroded). | |
| Basin | Overlies | Palaeozoic granites, volcanics and metasediments. |
| Underlies | - | |
| Subdivisions | Informal 'West', 'Central', 'South' and 'North' subdivisions are used onshore. | |
| Other | Offshore structure quite different from onshore. | |
| Indicators | Knowledge | Detailed field scale geophysical and well data onshore; regional geophysical data only offshore. |
| Basin type | Convergent margin foreland thrust loaded basin. | |
| System(s) | Gondwanan. | |
| Water Depth (m) | 0-4000 | |
| Exploration | Status | Frontier (offshore). |
| Wells | 0 offshore, 115 onshore petroleum exploration wells. | |
| Seismic line-km | Sparse 2D regional coverage offshore. | |
| Discoveries | Nil | |
| Shows | Widespread oil and gas shows have been encountered throughout the section. | |
| HC evidence | Active petroleum system (Maung and others, 1993). | |
| Geology | Source(s) | Late Permian coal measures and marine shales. |
| Reservoirs | Permian shallow marine to fluvial sands (but often affected by diagenesis); Triassic Narabeen Group has excellent reservoirs. | |
| Seals | Numerous Permo-Triassic intra-formational seals. | |
| Trap types | 1) Wrench related structures, 2) overthrust traps, 3) mild basin inversion features, 4) extension down to basement fault bound blocks, 5) sub-thrust traps, 6) stratigraphic traps, 7) extensional, combination traps. |
|
| Palaeogeographic summary | Early Permian: dominantly marine; late Early Permian to Late Permian: dominantly fluvial, with coal measures; Triassic: dominantly fluvial but some marine and volcanics; Jurassic-Cretaceous: eroded. | |
| Timing | Oil generation | Commenced Middle Jurassic to Early Cretaceous for Late Permian sources depending on location and amount of eroded section, late generation still occurring. A Late Cretaceous peak is probable. |
| Gas generation | Early Cretaceous to present. | |
| Trap formation | Types 2, 4 and 5 Early Permian, type 1 Early Permian to Triassic, type 3 Late Permian, type 6 Late Permian to Triassic, type 7 Early Cretaceous. | |
| Other key times | Major Late Cretaceous erosion accompanied breakup between Australia and the Lord Howe Rise. | |
| Other important information | 1) The offshore basin lies under a while migration path for several months
of the year; 2) The onshore basin includes large urban areas. |
|
| Geoscience Australia products available | 1) Harrington and others, 1989; 2) Maung and others, 1997. 3) Cadman and others, 1998. |
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