Geology and petroleum prospectivity of the deepwater Otway and Sorell basins: new insights from an integrated regional study*
A. Stacey A , C. Mitchell A , G. Nayak A , H. Struckmeyer A , M. Morse A , J. Totterdell A and G. Gibson AGeoscience Australia.
The APPEA Journal 51(2) 692-692 https://doi.org/10.1071/AJ10072
Published: 2011
Abstract
The frontier deepwater Otway and Sorell basins lie offshore of southwestern Victoria and western Tasmania at the eastern end of Australia’s Southern Rift System. The basins developed during rifting and continental separation between Australia and Antarctica from the Cretaceous to Cenozoic. The complex structural and depositional history of the basins reflects their location in the transition from an orthogonal–obliquely rifted continental margin (western–central Otway Basin) to a transform continental margin (southern Sorell Basin).
Despite good 2D seismic data coverage, these basins remain relatively untested and their prospectivity poorly understood. The deepwater (> 500 m) section of the Otway Basin has been tested by two wells, of which Somerset–1 recorded minor gas shows. Three wells have been drilled in the Sorell Basin, where minor oil shows were recorded near the base of Cape Sorell–1.
As part of the federal government-funded Offshore Energy Security Program, Geoscience Australia has acquired new aeromagnetic data and used open file seismic datasets to carry out an integrated regional study of the deepwater Otway and Sorell basins. Structural interpretation of the new aeromagnetic data and potential field modelling provide new insights into the basement architecture and tectonic history, and highlights the role of pre-existing structural fabric in controlling the evolution of the basins. Regional scale mapping of key sequence stratigraphic surfaces across the basins, integration of the regional structural analysis, and petroleum systems modelling have resulted in a clearer understanding of the tectonostratigraphic evolution and petroleum prospectivity of this complex basin system.
Andrew Stacey is a basin analyst/structural geologist working in Geoscience Australia’s Southern Frontiers project where he has been leading the deepwater Otway and Sorell basins prospectivity study. Andrew received a BSc (Hons) (Earth science) from UTS, Sydney in 2001 and completed a PhD at Tasmania University in 2009. Since joining Geoscience Australia in 2007, Andrew has been involved in seismic interpretation and structural mapping of the Bight and Otway-Sorell basins and in the acreage release program. Member: AAPG and PESA. |
Cameron Mitchell is a petroleum geoscientist in Geoscience Australia’s Southern Frontiers project. His interests are in basin and margin petroleum prospectivity analysis using seismic, remote sensing and physical acquisition, and integration in the 3D realm. Cameron has a particular interest in marine survey techniques. He has been responsible for managing several large data acquisition programs and, in 2007, was chief scientist of the Bight Basin sampling and seepage survey. Cameron is now involved in a tectonostratigraphic study of the deep-water Otway and Sorell basins as part of Geoscience Australia’s work in investigating the potential of Australia’s continental margins. |
Goutam Kumar Nayak is a geophysicist in Geoscience Australia’s Southern Frontiers project where he has been employed since 2008. Goutam completed an MSc (technology) in applied geophysics at the Indian School of Mines, Dhanbad, India. Afterwards, he joined the National Geophysical Research Institute (NGRI), Hyderabad, India where he worked for nearly 10 years, completing a PhD (aeromagnetic data interpretation) in 2004 at Osmania University, Hyderabad, India. Goutam’s research interest includes modelling and interpretation of potential field data. |
Heike Struckmeyer is a principal research scientist in Geoscience Australia’s petroleum and marine division. She graduated from the University of Göttingen, Germany, in 1981 and received a PhD from Wollongong University in 1989. Since joining Geoscience Australia in 1988, her work has been focused on the evolution and prospectivity of Australia’s northern, northwestern, eastern and southern margins, and on regional basin analysis and petroleum systems modelling. In recent years, she has worked on projects in the Browse, Bight and Arafura Basins. Member: AAPG, PESA. |
Michael Morse graduated with a BSc (Hons) (geophysics) from Melbourne University in 1984 and completed an MSc (IT) from UNSW in 2005. He began his geophysical career with Geoterrex Pty Ltd in 1984, joined Geoscience Australia (then BMR) and worked in aero magnetics, gravity and, for the previous 15 years, worked as a potential field specialist geophysicist in the petroleum and marine division. |
Jennie Totterdell is a principal research scientist in Geoscience Australia’s petroleum and marine division and project leader of the Southern Frontiers project. Since graduating from ANU, Jennie has worked on a range of regional, thematic and basin studies at Geoscience Australia. In the previous 10 years, her work has focused on offshore frontier basins, notably the Bight, Arafura and Browse basins. Her main areas of interest are the structural and stratigraphic evolution and petroleum potential of the southern Australian margin. Member: PESA. |
George Gibson has been a student at the universities of Edinburgh and Otago where he studied petrology and structural geology. After moving out from New Zealand in 1981, he was an academic for 10 years before joining the Commonwealth public service in late 1995. He has been with Geoscience Australia for 14 years, working first on the geodynamic evolution of Broken Hill and Mount Isa before joining the petroleum and marine division in 2007 to further his education on the origin and evolution of passive margins. Member: PESA, GSL, GSAm, GSA, GSNZ. |
References
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, 608–27.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, PESA Special Publication, 97—116.
Morse, M.P., Gibson, G.M., and Mitchell, C.H., 2009—Basement constraints on offshore basement architecture as determined by new aeromagnetic data acquired over Bass Strait and the western margin of Tasmania. Extended Abstract. Australian Society of Exploration Geophysicists and PESA, 20th International Geophysical Conference and Exhibition. Adelaide.
Nayak, G.K., Morse, M.P., Gibson, G.M., Stacey, A.R., and Mitchell, C.H., 2010—Structural architecture of the Otway and Sorell basins derived from potential field modelling. Extended Abstract. Australian Society of Exploration Geophysicists and PESA, 21st International Geophysical Conference and Exhibition. Sydney.
O’Brien, G.W., Boreham, C.J., Thomas, H., and Tingate, P.R. (2009). Understanding the critical success factors determining prospectivity, Otway Basin, Victoria. APPEA Journal 49, 129–70.
