Exmouth Sub-basin

Release Areas W16-24 and W16-25, Exmouth Sub-basin, Northern Carnarvon Basin, Western Australia

Highlights

Bids close for Release Area W16-24 on 23 March 2017.

Prequalification for Release Area W16-25 closes on 20 October 2016, with the cash bidding auction to be held on 2 February 2017.

  • One of Australia’s major oil producing provinces, adjacent to multi-Tcf gas fields
  • Proximal to Macedon gas pipeline with tieback to onshore gas plant
  • Shallow to deep water depths, 350–1100 m
  • Oil-prone Upper Jurassic and gas‑prone Triassic to Middle Jurassic source rocks
  • Triassic fault block and Cretaceous stratigraphic traps
  • Further guidance available, please refer to 2016 Special Notices

Release Areas W16-24 and W16-25 are within the northern Exmouth Sub-basin, approximately 75-125 km north of Exmouth. W16-25 comprises two graticular blocks and is available for cash bidding, while the more northerly W16-24 comprises a larger area of twelve graticular blocks, with a slight extension into the southern Exmouth Plateau (Figure 1) and is available for work program bidding. The Release Areas are in the vicinity of numerous oil and gas accumulations including Vincent/Van Gogh, Pyrenees/Macedon, Skiddaw/Laverda, Stybarrow and Coniston (Figure 1).

The Exmouth Sub-basin formed as one of a series of northeast–southwest trending, en-echelon structural depressions during the Pliensbachian to Oxfordian. Pre-rift sediments are of Permian and Early to Middle Triassic age, and are gas‑prone (Figure 2). The Upper Jurassic Dingo Claystone is the main oil-prone source rock within the Exmouth Sub-basin. Proven reservoirs occur within the Barrow Group and Dupuy Sandstone, with the Muderong Shale acting as the regional seal. Play types include fault block traps within the Mungaroo Formation with an intraformational or Dingo Claystone seal, stratigraphic plays within the Barrow Group and complex structural/stratigraphic Jurassic channel fill plays (Figure 3). Infrastructure is in-place for oil and gas production, with the Macedon gas pipeline in operation (Figure 1).

Figure 4 shows the existing data coverage in the vicinity of the Release Areas, with only one well, Furness 1, being located within Release Area W16-25. Release Area W16-24 has 2D seismic coverage, with an average line spacing of less than 5 km, and is largely covered by the HCA04 3D seismic survey. Release Area W16-25 has 2D seismic coverage, with an average line spacing of less than 2.5 km, and is fully covered by the HCA2000A 3D seismic survey, and has additional coverage from the West-Gorgon 3D and Vincent 3D seismic surveys that overlap parts of the Release Area.






Figures

Figure 1

Structural elements of the Exmouth Sub-basin and Exmouth Plateau in the vicinity of the 2016 Release Areas, showing petroleum fields, key wells, and the 2016 Release Areas


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Figure 2

Stratigraphy and hydrocarbon shows in the Exmouth Sub-basin and Exmouth Plateau, 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 Areas in the Exmouth Sub-basin: a. Lower Cretaceous (Barrow Group) low relief domed anticlinal play (adapted from Esso Australia Limited, 1983); b. Upper Triassic (Mungaroo and Brigadier formations) rotated fault block play with stratigraphic elements (adapted from Woodside Energy Ltd, 2006); c. Upper Triassic (Mungaroo Formation) horst block play (adapted from Esso Australia Limited, 1980); d. Lower Cretaceous (Barrow Group) rotated fault block play (adapted from Woodside Energy Ltd, 1999); and e. Upper Jurassic (Dupuy Formation) structural/stratigraphic channel play (adapted from McArdle et al, 2014). See Figure 1 for well locations


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Figure 4

Seismic and well data in the vicinity of the Release Areas in the Exmouth Sub-basin and Exmouth Plateau, Northern Carnarvon Basin


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