An exploration well intended to test a combined stratigraphic / structural play, such as Welcome Lake, on the north-western flank of the Patchawarra Trough is considered to have an unacceptably high risk. This risk should be minimised by further geological and geophysical studies, together with additional seismic surveys if considered necessary. The past exploration history of the Patchawarra Trough has shown that it has generated oil and gas in large quantities. These have been trapped in anticlinal structures, and fields such as Tirrawarra, Fly Lake and Kanowana will be produced commercially. It is suggested that many small anticlinal structures remain to be defined and tested, and that these will contain further accumulations. The greatest potential for medium to large hydrocarbon pools may depend upon the discovery of stratigraphic / structural traps on the northwestern flank of the trough. The most likely of these traps to be detected by current seismic techniques are the basinward plunging noses or valleys associated with wedgeout edges. At present the two best defined of these noses are Welcome Lake and the Fly Lake - Brolga - Moorari trend. A trapping mechanism cannot be mapped with surety at Welcome Lake at this stage. Further study of the Fly Lake 1, 2 and 3 well data and detailed seismic work is considered necessary prior to any decision to drill on the flank of the Patchawarra Trough.