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Dampier Sub-basin

Release Area W16-22, Dampier Sub-basin, Northern Carnarvon Basin, Western Australia

Highlights

Prequalification for Release Area W16-22 closes on 20 October 2016, with the cash bidding auction to be held on 2 February 2017.

  • Within one of Australia’s premier offshore producing basins
  • Cash Bid Release Area overlies the Tusk and Oryx oil accumulations and is close to numerous other oil and gas accumulations including Chamois, Corvus, Stag, Wandoo and Reindeer
  • Shallow water depths (40–50 m)
  • Oil-prone Upper Jurassic and gas-prone Triassic to Middle Jurassic source rocks
  • Stacked structural and stratigraphic targets at Triassic, Jurassic and Lower Cretaceous levels
  • Further guidance available, please refer to 2016 Special Notices

Release Area W16-22 is a small area, comprising two graticular blocks, that is considered mature in exploration terms and is available for cash bidding. The area intersects the Tusk and Oryx oil fields and is approximately 70 km northeast of Barrow Island and 70 km northwest of Dampier (Figure 1).

The Dampier Sub-basin is one of a series of large rift depocentres of the Northern Carnarvon Basin. The sub-basin is an elongate northeast-trending depocentre 170 km in length and 100 km in width, and contains Paleozoic to Cenozoic sedimentary successions 10‑20 km in thickness (Figure 2). The main structural elements of the Dampier Sub-basin are aligned northeast-southwest: from northwest to southeast these are; the Kendrew Trough, Madeleine Trend, Lewis Trough, Legendre Trend and Enderby Terrace (Figure 3).

The Dampier Sub-basin hosts proven petroleum systems. Upper Triassic, Lower–Middle and Upper Jurassic source rocks have expelled hydrocarbons that are now reservoired in both structural and stratigraphic traps. Gas is predominantly sourced from Triassic to Middle Jurassic fluvio-deltaic sediments of the Mungaroo and Brigadier formations, the Murat Siltstone, and the Athol and Legendre formations. Oil is predominantly sourced from the Upper Jurassic Dingo Claystone. Structural trap styles in the sub-basin include tilted fault blocks, fault dependent rollovers, anticlines, drape features and horsts (Figure 3).

Figure 4 shows the existing data coverage of the Dampier Sub-basin. Although well coverage is not dense within the sub-basin, Brocket 1 and Oryx 1 wells lie within the Release Area and both have oil shows.  The Release Area is also entirely covered by the Panaeus99ab 3D seismic survey. The release area is close to established infrastructure that could facilitate the development of discoveries (Figure 1).






Figures

Figure 1

Structural elements of the Dampier Sub-basin in the vicinity of the 2016 Release Area, showing petroleum fields, key wells, and the 2016 Release Area


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Figure 2

Stratigraphy and hydrocarbon shows in the Dampier and Beagle sub-basins based on the Northern Carnarvon Basin Biozonation and Stratigraphy Chart (Kelman et al, 2013). Geologic Time Scale after Gradstein et al (2012)


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Figure 3

Selected play types in the vicinity of the Release Area in the Dampier Sub-basin: a. Lower Cretaceous (Muderong Shale) structural/stratigraphic and Upper Triassic–Lower Jurassic (Mungaroo Formation, Athol Formation) horst and tilted fault-block plays (adapted from Ampol Exploration Limited, 1992) b. Lower Cretaceous (Angel Formation) low relief, fault modified, anticlinal play (adapted from Woodside Offshore Petroleum Pty Ltd, 1996); c. Lower Jurassic (Legendre Formation) rollover anticlinal play (adapted from Apache Energy, 2005); d. Upper Triassic (Mungaroo Formation) and Lower Jurassic (Athol Formation) tilted fault-block plays with associated drapes (adapted from Apache Energy, 2008); and e. Permian (Kennedy Group) and Triassic (Locker Shale, Mungaroo Formation) fault-bounded anticlinal play (adapted from Australian Occidental Pty Ltd, 1983). See Figure 1 for well locations


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Figure 4

Seismic and well data in the vicinity of the Release Area in the Dampier Sub-basin, Northern Carnarvon Basin


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