Main Content
The North West Shelf Digital Atlas (hereafter referred to as NWSDA) provides the industry with a modern, adaptable digital map library of Australia's North West Shelf hydrocarbon province.
The NWSDA contains a series of gridded two-way-time structure maps (ZMap and Petrosys formats) of most of the important stratigraphic boundaries in the North West Shelf region. Additional features are also presented within the NWSDA, designed to aid in the accessibility of the data for the industry.
PGS have taken released AGSO interpretation, added additional data, utilized further well control and produced a series of regional gridded surfaces over the NW Shelf. Overcoming hardware and software limitations associated with a project of this size and scale, PGS have output a library of data on one common reference grid in ready to use, project and workstation formats.
The NWSDA is the perfect companion to the PGS Australian MegaSurveys providing the user with not just the bigger picture but a comprehensive guide to all of the NWS petroleum provinces.
The Gridded Surfaces
The products of the interpretation are time structure maps in the form of gridded time surfaces in units of milliseconds two way travel time. A total of 7 horizon grids are presented, in digital format and as pre-prepared maps.
- Sea Bed
- Base Miocene
- Top Palaeocene
- Base Tertiary
- Valanginian Unconformity
- Callovian unconformity
- Top Permian
The coverage of the horizons were primarily defined by the extent of the released AGSO interpretation. Subsequently, the addition of the CTT and VTT plus the Vulcan and Carnarvon MegaSurvey data sets required the extents of certain horizons to be modified to incorporate the new data.
The various interpretation data sets from each survey were initially available in a number of differing UTM zones, ranging from 50 to 53. To provide the regional picture, all data was converted to UTM51 with a central meridian of 12300'E prior to gridding.
Once all grids had been generated for the 2D surveys, the horizon data from the PGS Vulcan and Carnarvon MegaSurveys was incorporated.
The Interpretation
In addition to the AGSO interpretation of thirteen surveys covering the North West Shelf, both the VTT and CTT surveys were further interpreted. Once combined, all fifteen surveys provided an extensive coverage of 2D data.
With a suitable 2D interpretation in place, the interpreted horizons of the PGS Carnarvon and Vulcan MegaSurveys were incorporated.
The location and extent of the seismic lines and 3D data employed are available in Adobe PDF format. The seven horizons may be viewed within their stratigraphic context as a large (10Mb+) Adobe PDF format or as a smaller JPEG image.
To give a regional view of the NWS a set of regional geoseismic lines have been produced over the key basins.
- NWSDA Geoseismic Profile 1
- NWSDA Geoseismic Profile 2
- NWSDA Geoseismic Profile 3
- NWSDA Geoseismic Profile 4
- NWSDA Geoseismic Profile 5
- NWSDA Geoseismic Profile 6
Well Database
The NWSDA well database provided by Geoscience Australia and arranged in a Microsoft Access format gives an extensive coverage for the North West Shelf. Well header information, formation tops, time depth curves and deviation data are included in the database. To assist in accessibility, well header and information is additionally presented as printable, well summary reports.
A contemporary online resource is provided by Geoscience Australia. The National Petroleum Wells Database can be accessed from the Geoscience Australia website.
Other Data
By orienting all available data into a master grid framework it allow the ability to easily add further data into the digital picture. This allows the user to have the ability to compare and contrast maps and grids quickly and efficiently. Other data types that has so far been incorporated into the NWSDA include:
- Bouger and Free Air Gravity Data
- Magnetic Data
- Total Organic Carbon Data
- Hydrogen Index Data
- Vitrinite Reflectance Data
- Bathymetry and Topographic Data
- Regional Seismic Lines
