The Great Australian Bight Seismic Reprocessing Package comprises 21,290 km of reprocessed seismic data, with interpretation of key horizons, together with extensive satellite SAR seep data.
The Great Australian Bight has been included in the Australian Government’s 2009 acreage release, to be formally announced in May 2009, and we also anticipate a 2010 acreage release. Geoscience Australia have recently published results from a geological sampling study, with promising evidence for a world class Cretaceous source rock in the Bight Basin.
The Bight Basin is one of the few remaining large frontier basins in the world, and covers an area in excess of 150,000 km2 along Australia’s southern margin. Water depths range between 200 metres on the shelf margin to +5,000 metres on the outer reaches of the Basin. The Ceduna sub-Basin is one of three sub-Basins comprising the Bight Basin, the Eyre and Recherche Sub-Basins being the other two. Each of these contain thick sedimentary sequences, the Ceduna sub-Basin in particular contains sediment fill up to 18-20 km thick.
There are potentially a variety of petroleum systems at a number of key stratigraphic intervals within the Ceduna sub-Basin. The sediments most likely to possess the highest levels of prospectivity are thought to lie within Middle-Late Cretaceous deltaic and marine deposits. A second sequence of potentially prospective units lies within deeper Late Jurassic fluvio-lacustrine deposits.
A recent Geoscience Australia (GA) geological sampling survey conducted in the GAB has provided new evidence for the presence of potential oil-prone source rocks. The study also predicts the character of the potential source rocks improve basin-ward. Two exploration wells have been drilled to date in the Ceduna sub-Basin; Potoroo-1, drilled in 1975 by Shell, and Gnarlyknots-1A, drilled in 2003 by Woodside. These wells sampled proximal locations of the Cretaceous depositional system. The prospective sequences that GA’s basin modeling results predict lie in more distal basin locations remain untested by drilling to date.
With the new results of the GA source rock study the Ceduna sub-Basin now possesses all the key geological attributes required to become a highly prospective oil and gas province. GA predicts that this region is potentially one of the most prospective deepwater frontier basins in offshore Australia. However, careful targeting and a good understanding of the depositional system are vital to optimizing the potential resources in this region. To help achieve this required level of understanding our data package will be accompanied by an extensive fully integrated interpretation review evaluating the prospectivity of the Ceduna sub-Basin to facilitate and aid any future exploration projects.
The project is comprised of:
- 15,978 km PSTM reprocessing of Flinders 2D seismic data set
- 5,315 km PSTM reprocessing of Deepwater GAB (DWGAB) seismic data set
- ~48 Radarsat scenes, ~47 ERS/Envisat/Palsar scenes satellite data
- Regional seismic interpretation of key horizons
- Trim 3D Post-stack Reprocessing
- 1,250km2 post-stack reprocessing &
- phase-matching of existing 3D to the
- PSTM reprocessed 2D grid
Standard 2D Deliverables Each purchaser and group member will receive one copy of:
- A SEGY format archive tape of the final PSTM seismic data
- An ASCII format diskette containing the seismically derived velocity field
- A diskette with navigation data of the processed lines
- A diskette with sp/cdp relationship data
- All satellite SAR data scenes
- Seismic Interpretation for key horizons
- Gathers (Demultiple Gathers or PSTM Gathers)
- Angle Stacks (nears, mids, fars)
Integrated Interpretation Report
There is also a comprehensive interpretation report available to licensees of the Reprocessing package and the Ceduna Aeromagnetic survey (currently being acquired). This report shall incorporate the new and reprocessed seismic data, existing marine gravity data, the new aeromagnetic data and extensive satellite seep data covering the Bight Basin.
With the seismic interpretation and seep data providing good geological controls, the integrated interpretation report will include:
- Generation of suitable imagery of airborne magnetic data
- Structural interpretation of existing marine gravity and airborne magnetic data (including basement structures and intra-sedimentary structures)
- Depth to basement study, as well as depth to other horizons of interest that are imaged by the magnetic and gravity data
- Construction of key modelled cross-sections
- 3D inversion of key areas of existing marine gravity data
- Provision of summary report, in Powerpoint presentation
- Provision of all products in digital GIS format
Seismic reprocessing of the DWGAB grid is now complete and ready for delivery. The Flinders 2D grid is being nearing completion and will be ready to deliver early April 2009.
The satellite seep data is available immediately, however will be incorporated into the interpretation report, which is scheduled to be delivered October 2009 - over six months prior to the blocks closing for bids.