Bids close 21 April 2016
- Under-explored Mesozoic–Cenozoic basin
- Adjacent to the gas producing areas of the inner Otway Basin
- Overlies large areas of the frontier Nelson Sub-basin, a main depocentre within the Otway Basin
- Sub-basin contains up to 8 km of sediment
- Potential presence of petroleum systems proven to be productive in adjacent basin
- Potential good quality reservoirs and seals, oil- and gas-prone source rocks and active petroleum systems
- Deep to ultra-deep water depths, 250–3400 m
- Close to Thylacine and Geographe Gas Pipeline
- Special Notices apply, refer to Guidance Notes
Release Areas V15-1, T15-1 and T15-2 are located on the continental shelf and slope within the Nelson Sub-basin—a frontier exploration province. The areas lie to the south of an established gas producing region in the inner Otway Basin that provides gas for the southeastern Australian energy market. (Figure 1). The greater Melbourne region currently represents Australia’s largest domestic gas market and is supported by a local petroleum refining industry. The Release Areas lie between 20 km and 210 km from the gas pipeline that services the Thylacine and Geographe gas fields. Water depths range from 250 m to 3400 m within V15-1, 260 m to 2400 m in T15-1 and 520 m to 3300 m in T15-2.
The Nelson Sub-basin contains up to 5 s TWT (~8 km) of Cretaceous sediments that are overlain by a thin Cenozoic succession (Figure 2 and Figure 3). The basal section, interpreted to comprise the non-marine, fluvio-lacustrine Lower Cretaceous Crayfish and Eumeralla supersequences (Otway Group), is overlain by a thick, basinward-thickening Upper Cretaceous succession that comprises prodelta and open marine equivalents of the Shipwreck and Sherbrook supersequences (equivalent to the Sherbrook Group). In hydrocarbon producing areas of the Otway Basin, the Waarre and Flaxman formations of the Shipwreck Supersequence, as well as the “Thylacine Sandstone Member” of the Belfast Mudstone, are important petroleum reservoirs.
Although modelling suggests that source rocks within the Lower Cretaceous succession are overmature across much of the deepwater basin, the presence of a thick, predominantly marine Upper Cretaceous succession, and geochemical analyses that suggest input from Upper Cretaceous source rocks in outboard wells, provide encouragement that active petroleum systems are present in the deepwater Otway Basin.
Figure 4 shows the location of seismic and well data within the Release Areas. Numerous 2D and 3D seismic surveys have been acquired. These include the Fugro DS01 and DS02 surveys and the OS02 (Santos), Aragorn (Woodside) and Brandt (Santos) surveys, respectively. The area is also covered by good quality aeromagnetic data. Release Area V15-1 includes the Armit 1 exploration well drilled by Santos in 2004.
Petroleum systems elements
Infrastructure and markets
The Nelson Sub-basin is a frontier exploration province and lacks existing infrastructure. The Release Areas, however, lie between 20 and 210 km from the gas pipeline that services the Thylacine and Geographe gas fields in the adjacent Inner Otway Basin.
As this is a frontier area, primary exploration risks relate to the lack of well control and modern, good quality seismic data. The critical exploration risks are associated with the presence and maturity of source rocks, the presence of effective seals and fault seal integrity. Fault-seal integrity may be less of a risk in the Nelson Sub-basin than in other parts of the deepwater Otway Basin, as the area has been less affected by Late Cretaceous and Cenozoic faulting.
Wells Data and Seismic Survey listings for the Nelson Sub-basin are available on the Supporting Information page.
Geoscience Australia products
Regional geology and seismic
- Petroleum geology inventory of Australia's offshore frontier basins. Geoscience Australia Record by Totterdell et al, 2014.
- Geology and hydrocarbon prospectivity of the deepwater Otway and Sorell basins, offshore southeastern Australia. Geoscience Australia Record by Stacey et al, 2013.
- Basement structure and its influence on the pattern and geometry of continental rifting and breakup along Australia’s southern rift margin. Geoscience Australia Record by Gibson et al, 2012.
- Time-Depth Functions for the Otway Basin. Geoscience Australia Record by Petkovic, 2003.
- An Audit of Selected Offshore Petroleum Exploration Wells in the Otway Basin, Southeastern Australia. Geoscience Australia Record by Smith et al, 2003.
- Deep Structure of the Otway Basin, Southeastern Australia, Survey 137 (Phases 1 and 2): Post-cruise report. Australian Geological Survey Organisation Record by Blevin et al, 1995.
- NGMA/PESA Otway Basin Symposium, Melbourne, 20 April 1994: Extended Abstracts. Australian Geological Survey Organisation Record by Finlayson, 1994.
- Otway Basin Seismic Test Survey 1991 : Operational Report. Australian Geological Survey Organisation Record by Wake-Dyster et al, 1994.
- Otway Basin Seismic Survey 1992 : Operational Report. Australian Geological Survey Organisation Record by Wake-Dyster et al, 1994.
- BMR Cruise 67: Otway Basin and west Tasmanian sampling. Bureau of Mineral Resources Report by Exon et al, 1992.
- Offshore Otway Basin Study. Australian Geological Survey Organisation Geographic Dataset by Williamson,1988.https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&catno=20829
- Extended abstracts: Otway Basin Workshop, Canberra, 17 March 1987. Bureau of Mineral Resources Record, 1987.
- Otway Basin–Biozonation and Stratigraphy Chart No.34. Geoscience Australia Chart by Mantle, 2009.
- New and Revised Palynological Data for the Otway Basin. Geoscience Australia Record by Monteil et al, 2004.
- Otway Basin - Biostratigraphic Dataset. Geoscience Australia Dataset by Buckler, 2001.
- Otway Basin Biozonation and Stratigraphy Chart No.9. Geoscience Australia Chart by Chaproniere, 1998.
Petroleum systems and accumulations
- The Oils of Eastern Australia. Geoscience Australia Report by Summons et al, 2002.
- South-eastern Australia Surface Geochemistry II: Light Hydrocarbon Geochemistry in Bottom-waters of the Gippsland Basin, Eastern Otway Basin, Torquay Sub-basin and the Durroon Sub-basin. Vols 1 and 2. Australian Geological Survey Organisation Record by Bishop et al, 1992.
- Australian Petroleum Accumulations Report. Otway Basin, South Australia, Victoria and Tasmania. Australian Geological Survey Organisation Report by Miyazaki, 1990.
- Preliminary Post-cruise Report: Hydrocarbon Gas Geochemistry in sediments of the offshore Otway and Gippsland Basins: Project 9131.20. Bureau of Mineral Resources Record by Heggie and O’Brien, 1988.
Search for these and other Geoscience Australia reports and products at www.ga.gov.au/search
Contact Geoscience Australia’s Sales Centre for more information or to order these reports or products, phone +61 (0)2 6249 9966, email email@example.com
BLEVIN, J.E. AND CATHRO, D.L., 2008—Australian Southern Margin Synthesis, Project GA707. Client report to Geoscience Australia by FrOG Tech Pty Ltd. https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&catno=68892
BOREHAM, C.J., HOPE, J.M., JACKSON, P., DAVENPORT, R., EARL, K.L., EDWARDS, D.S., LOGAN, G.A. AND KRASSAY, A.A., 2004—Gas–oil–source correlations in the Otway Basin, southern Australia. In: Boult, P.J., Johns, D.R. and Lang, S.C. (eds), Eastern Australasian Basins Symposium II, Petroleum Exploration Society of Australia, Special Publication, 603–627.
CLIFF, D.C.B., TYE, S.C. AND TAYLOR, R., 2004—The Thylacine and Geographe gas discoveries, offshore eastern Otway Basin. The APPEA Journal 44(1), 441–462.
DUDDY, I.R., EROUT, B., GREEN, P.F., CROWHURST, P.V. AND BOULT, P.J., 2003.—Timing constraints on the structural history of the western Otway Basin and implications for hydrocarbon prospectivity around the Morum High, South Australia. The APPEA Journal, 43(1), 59–83.
GEOLOGICAL SURVEY OF VICTORIA, 1995—The stratigraphy, structure, geophysics and hydrocarbon potential of the Eastern Otway Basin. Geological Survey of Victoria, Report 103, 241 pp.
GIBSON, G.M., MORSE, M.P., IRELAND, T.R. AND NAYAK, G.K., 2011—Arc-continent collision and orogenesis in western Tasmanides: Insights from reactivated basement structures and formation of an ocean-continent transform boundary off western Tasmania. Gondwana Research, 19, 608–627.
GIBSON, G. M., TOTTERDELL, J.M., MORSE, M. P., GONCHAROV, A., MITCHELL, C.H. AND STACEY, A.R., 2012—Basement structure and its influence on the pattern and geometry of continental rifting and breakup along Australia’s southern rift margin. Geoscience Australia, Record, 2012/47.
GRADSTEIN, F.M., OGG, J.G. SCHMITZ, M.D. AND OGG, G.M. (eds), 2012—The Geologic Time Scale 2012: Volumes 1 & 2. Elsevier BV, 1144 pp.
HALL, M. and KEATLEY, J. 2009—Otway Basin, stratigraphic and tectonic framework. GeoScience Victoria 3D Victoria Report 2, Department of Primary Industries.
KRASSAY, A.A., CATHRO, D.L. AND RYAN, D.J., 2004—A regional tectonostratigraphic framework for the Otway Basin. In: Boult, P.J., Johns, D.R. and Lang, S.C. (eds), Eastern Australasian Basins Symposium II, Petroleum Exploration Society of Australia, Special Publication, 97–116.
LUXTON, C.W., HORAN, S.T., PICKAVANCE, D.L. AND DURHAM, M.S., 1995—The La Bella and Minerva gas discoveries, offshore Otway Basin. The APEA Journal, 35, 405–417.
MANTLE, D.J., BERNECKER, T., KELMAN, A.P. AND PATRIDGE, A.D., 2009—Otway Basin Biozonation and Stratigraphy, 2009 Chart 34. In: Smith, T.E., Kelman, A.P., Nicoll, R.S., Laurie, J.R. and Le Poidevin, S.R., 2013. Geoscience Australia's Basin Biozonation and Stratigraphy Chart Series. Basin Biozonation and Stratigraphy Chart Series.
O’BRIEN, G.W., BERNECKER, T., THOMAS, J.H., DRISCOLL, J.P. AND RIKUS, L., 2006—An assessment of the hydrocarbon prospectivity of Areas VIC/O-06(1), VIC/O-06(2), VIC/O-06(3) and V06-1, eastern onshore and offshore Otway Basin, Victoria, Australia. Victorian Initiative for Minerals and Petroleum Report 90, Department of Primary Industries.
O’BRIEN, G.W., BOREHAM, C.J., THOMAS, H.J. AND TINGATE, P.R., 2009—Understanding the critical success factors determining prospectivity—Otway Basin, Victoria. The APPEA Journal, 49(1), 129–170.
PARTRIDGE, A.D., 2001—Revised stratigraphy of the Sherbrook Group, Otway Basin. In: Hill, K.C. and Bernecker, T. (eds), Eastern Australian Basins Symposium, A Refocused Energy Perspective for the Future, Petroleum Exploration Society of Australia, Special Publication, 455–464.
STACEY, A.R., MITCHELL, C.H., STRUCKMEYER, H.I.M. AND TOTTERDELL, J.M., 2013—Geology and hydrocarbon prospectivity of the deepwater Otway and Sorell basins, offshore southeastern Australia. Geoscience Australia, Record, 2013/02.
TOTTERDELL, J., HALL, L., HASHIMOTO, T., OWEN, K. AND BRADSHAW, M., 2014—Petroleum geology inventory of Australia's offshore frontier basins. Geoscience Australia, Record, 2014/009.
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