This presentation was given at APPEA 2016 Conference 6-8 June 2016, by I Longley (GIS-Pax Pty Ltd) and J Dirstein (Total Depth Pty Ltd).
The deep water portion of the Great Australian Bight remains an untested basin with the Gnarlyknots-1A well drilled in 2003 not penetrating deep enough to test the well’s targets within the Upper Cretaceous Ceduna Delta section. If an anoxic marine shale source system, that is an effective source in many parts of West Africa, is present beneath the delta, then this cou
ld supply a material oil charge into the numerous fault block structures identified on seismic data. With either wells du to be drilled in the next few years, this area will be one of the most active exploration frontier settings in the region.
Since Australia has an open file system for technical data, the regional Flinders 2000 2D Marine Seismic Interpretation report containing five regional time structure maps is now available in the public domain, as is the Gnarlyknots-1A well data and the raw seismic data from the Ceduna 3D survey acquired in 2012. These data were used to evaluate the untested Confucian play interval with the construction of reservoir presence and quality, seal and charge relative probability maps made from various proxies that were then stacked to show areas of relative prospectively. This traditional approach was supplemented by an example showing pre-interpretation surfaces from the pre-Cenomanian portion of the 2D volume to help develop a better understanding of the potential prospectivity of deeper intervals not captured on the submitted open file maps. The workflow presented here suggests some parts of the Ceduna Sub Basin are significantly more prospect than others. Moreover, we demonstrate that even in frontier settings with minimal well data, pre-interpretation processing and simple play analysis together can be a useful and efficient approach for delivering significant insights into prospectively. This workflow will ultimately promote more exploration thinking and activity in the future.
To get the full presentation: Prospectivity and Play Analysis in the frontier Great Australian Bight