OFFSHORE PETROLEUM EXPLORATIONACREAGE RELEASE AUSTRALIA 2014

Release Area W14-19,

Eyre Sub-basin, Bight Basin,Western Australia

Figure 1 Location of the 2014 Release Area in the Eyre Sub-basin of the Bight Basin

HighlightsWork program bids close 2 April 2015 Under-explored frontier Jurassic–

Cretaceous rift-basin Water depths 100–2800 m Adjacent to active exploration permits

in Ceduna Sub-basin Deltaic and shallow marine depositional

systems Regional 2D seismic coverage Well control provided by Jerboa 1 Special Notices apply, refer to Guidance

Notes

Release Area W14-19 is located 75 to 200 km off the south coast of Western Australia, approximately 400 km east of Esperance, and comprises 360 graticular blocks covering the entire Eyre Sub-basin. The sub-basin represents an offshore frontier where only one exploration phase occurred in the late 1970s to early 1980s, culminating in the well Jerboa 1 which encountered minor residual oil indications.

The Eyre Sub-basin is located in the eastern Bight Basin and comprises a series of Middle Jurassic–Early Cretaceous east-northeast-striking en-echelon half graben. The sub-basin covers an area of approximately 9200 km2, and contains up to 3500 m of Jurassic–Cretaceous sediments. Geological understanding of the Eyre Sub-basin is based on interpretation of a generally good quality, regional scale, 2D seismic data set, which has a line spacing of approximately 20–40 km, and the Jerboa 1 well, drilled by Esso Australia in 1980, which provides valuable stratigraphic control and constraint on seismic-based facies interpretation. Additional stratigraphic information for the Cenozoic section is provided by the results of Ocean Drilling Program Site 182 wells (Feary et al, 2000, 2004).

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DISCLAIMER: This document has been developed as a guide only. Explorers should not rely solely on this information when making commercial decisions. Image courtesy of BHP Billiton Petroleum Pty Ltd.

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DISCLAIMER: This document has been developed as a guide only. Explorers should not rely solely on this information when making commercial decisions. Image courtesy of BHP Billiton Petroleum Pty Ltd.

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Figure 2 Main structural elements of the Eyre Sub-basin showing well coverage, the location of the seismic section and the 2014 Release Area

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Figure 3 Stratigraphy of the Eyre Sub-basin, based on the Bight Basin Biozonation and Stratigraphy Chart (Mantle et al, 2009). Geologic Time Scale after Gradstein et al (2012)

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Figure 4 Seismic line DWGAB-28 across the Eyre Sub-basin. Location of the line is shown in Figure 2

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Figure 5 Seismic and well data coverage in the vicinity of Release Area W14-19 in the Eyre Sub-basin, Bight Basin

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Petroleum systems elementsEyre Sub-basin

Sources Late Jurassic to Early Cretaceous syn-rift lacustrine shales

Early Cretaceous lacustrine deposits and coal

Reservoirs Sandy facies at base of Early Cretaceous supersequences

Southern Right Bronze Whaler Blue Whale White Pointer

Highstand and lowstand sediments at base of Paleogene

Wobbegong Supersequence

Seals Shale facies

Upper Minke Supersequence Southern Right Supersequence

Fault seal

Bronze Whaler Supersequence Sea Lion Supersequence Minke Supersequence White Pointer Supersequence

Traps Structural

Footwall blocks of half-graben bounding faults

Stratigraphic

Onlap onto hanging wall blocks and relay ramps Reactivation anticlines Progradational sandy facies within Wobbegong Supersequence

Infrastructure and marketsThe Eyre Sub-basin is an offshore frontier near the border of Western Australia and South Australia and awaits its first hydrocarbon discovery. Current large scale exploration activity in the adjacent Ceduna Sub-basin will require a supportive infrastructure which could be expanded to cater for future activities in the 2014 Release Area.

Critical risksA key prospectivity risk in the Eyre Sub-basin is the lack of hydrocarbon charge in areas where the basin fill is less than 2500–3000 m. Ruble et al. (2001) argued that timing of trap formation, generation, expulsion and reactivation are all critical issues for the prospectivity. This particularly applies to the timing of migration and accumulation relative to the period of uplift and erosion in the latest Cretaceous–early Paleocene. Given the localised nature of potential source kitchens, accumulation size may also be an issue in the sub-basin.

Jerboa 1 is considered to have been a valid structural test of a drape structure over a basement block, and the cause of failure is likely to be breaching of the trap following the accumulation of the hydrocarbon column (Messent, 1998). Seismic data shows that a group of small faults branch upwards from the half-graben bounding fault, the result of Late Cretaceous fault reactivation (possibly related to the period of uplift), as well as compaction.

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Data setsFor the Wells Data Listing go to http://www.petroleum-acreage.gov.au/2014/support/geo.html

For the Seismic Surveys Listing go to http://www.ga.gov.au/energy/projects/acreage-release-and-promotion/2014.html#data-packages

Geoscience Australia productsRegional geology and seismic Australian Southern Margin Synthesis, Project GA70, 2008. GEOCAT 68892

Basement structure and its influence on the pattern and geometry of continental rifting and breakup along Australia's southern rift margin, 2012. GEOCAT 74031

Stratigraphy Geoscience Australia’s Basin Biozonation and Stratigraphy Chart Series: Bight Basin Biozonation and

Biostratigraphy Chart 35, 2014. GEOCAT 76687

Contact Geoscience Australia’s Sales Centre for more information or to order these reports or products, phone +61 (0)2 6249 9966, email sales@ga.gov.au

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Key referencesBein, J. and Taylor, M.L., 1981. The Eyre Sub-basin: recent exploration results. The APEA Journal, 21(1), 91–98.

Blevin, J.E., Totterdell, J.M., Logan, G.A., Kennard, J.M., Struckmeyer, H.I.M. and Colwell, J.B., 2000. Hydrocarbon prospectivity of the Bight Basin—petroleum systems analysis in a frontier basin. In: 2nd Sprigg Symposium – Frontier Basins, Frontier Ideas, Adelaide, 29–30 June, 2000. Geological Society of Australia, Abstracts 60, 24–29.

Boreham, C.J., Krassay, A.A. and Totterdell, J.M., 2001. Geochemical comparisons between asphaltites on the southern Australian margin and Cretaceous source rock analogues. In: Hill, K.C. and Bernecker, T. (eds), Eastern Australasian Basins Symposium: a refocused energy perspective for the future. Petroleum Exploration Society of Australia, Special Publication, 531–541.

Bradshaw, B.E., Rollet, N., Totterdell, J.M. and Borissova, I., 2003. A revised structural framework for frontier basins on the southern and southwestern Australian continental margin. Geoscience Australia Record 2003/03.

Feary, D.A. and James, N.P., 1998. Seismic stratigraphy and geological evolution of the Cenozoic, cool-water Eucla Platform, Great Australian Bight. AAPG Bulletin, 82 (5A), 792–816.

Feary, D.A., Hine, A.C., Malone, M.J. et al., 2000. Leg 182 summary: Great Australian Bight—Cenozoic cool-water carbonates. Proceedings of the Ocean Drilling Program, Initial Reports Volume 182.

Feary, D.A., Hine, A.C., James, N.P. and Malone, M.J., 2004. Leg 182 synthesis: exposed secrets of the Great Australian Bight. Proceedings of the Ocean Drilling Program, Scientific Results, Volume 182.

Liu, K. and Eadington, P.J. 1998. Hydrocarbon petrography of Jerboa-1, Eyre Sub-basin, The Great Australian Bight. CSIRO Petroleum Confidential Report 98-031 (unpublished).

Messent, B.E.J., Wilson, C. and Flynn, K., 1996. Assessment of the seal potential of Tertiary carbonates, Duntroon Basin, South Australia. The APPEA Journal, 36 (1), 233–247.

Morgan, R.P., 1999. Palynology review of the pre-Tertiary of the Bight–Duntroon basins. Report for Primary Industries and Resources South Australia (unpublished).

Quinn, D.M.T., 1999. An evaluation of seals, reservoirs, and fault sealing potential in the Eyre Sub-basin, Great Australian Bight. BSc Honours Thesis, University of Adelaide, National Centre for Petroleum Geology and Geophysics (unpublished).

Ruble, T.E., Logan, G.A., Blevin, J.E., Struckmeyer, H.I.M., Liu, K., Ahmed, M., Eadington, P.J. and Quezada, R.A., 2001. Geochemistry and charge history of a palaeo-oil column: Jerboa-1, Eyre Sub-basin, Great Australian Bight. In: Hill, K.C. and Bernecker, T. (Eds), Eastern Australasian Basins Symposium: a refocused energy perspective for the future. Petroleum Exploration Society of Australia, Special Publication, 521–530.

Stagg, H.M.V., Cockshell, C.D., Willcox, J.B., Hill, A.J., Needham, D.V.L., Thomas, B., O’Brien, G.W. and Hough, L.P., 1990. Basins of the Great Australian Bight region, geology and petroleum potential. Bureau of Mineral Resources, Australia, Continental Margins Program Folio 5.

Struckmeyer, H.I.M., Totterdell, J.M., Blevin, J.E., Logan, G.A., Boreham, C.J., Deighton, I., Krassay, A.A. and Bradshaw, M.T., 2001. Character, maturity and distribution of potential Cretaceous oil source rocks in the Ceduna Sub-basin, Bight Basin, Great Australian Bight. In: Hill, K.C. and Bernecker, T. (eds), Eastern Australian Basin Symposium: a refocused energy perspective for the future. Petroleum Exploration Society of Australia, Special Publication, 543–552.

Totterdell, J.M., Blevin, J.E., Struckmeyer, H.I.M., Bradshaw, B.E., Colwell, J.B. and Kennard, J.M., 2000. A new sequence framework for the Great Australian Bight: starting with a clean slate. The APPEA Journal, 40(1), 95–117.

Totterdell, J.M. and Krassay, A.A., 2003. Sequence stratigraphic correlation of onshore and offshore Bight Basin successions. Geoscience Australia Record 2003/02.

Totterdell, J.M. and Mitchell, C. (editors), 2009. Bight Basin geological sampling and seepage survey, R/V Southern Surveyor Survey SS01/2007: post-survey report. Geoscience Australia Record 2009/24.

Wilcox, J.B., Stagg, H.M.J., Davies, H.L. Shipboard Party. Rig Seismic research cruises 10 and 11: geology of the central Great Australian Bight region. Bureau of Mineral Resources, Geology and Geophysics, Report 286.

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