
%0 Journal Article
%A Auld, K. 
%A Thomas, B. 
%A Goodall, J. 
%A Benson, J. 
%T THE JOHN BROOKES GAS DISCOVERY&#x2014;AN EVOLVING STORY
%J The APPEA Journal
%D 2002/06/30
%V 42
%N 1
%P 443-459
%K 
%R https://doi.org/10.1071/AJ01024
%U https://www.publish.csiro.au/paper/AJ01024 
%X John Brookes&#x2013;1 was drilled as part of a work commitment for the WA-214-P Joint Venture in 1998 and discovered an 85 m gross dry gas column. The objective of the well was to test a structural closure at the base of the Muderong Shale regional seal on the Tryal Rocks anticline, up-dip from Tryal Rocks&#x2013;1, drilled in 1970. Tryal Rocks&#x2013;1, the 31st offshore well to be drilled within the Carnarvon Basin, WA, was initially considered a dry hole. However, a review of the well data in 1997&#x2013;98 suggested that Tryal Rocks&#x2013;1 might contain a hydrocarbon column. The mapping of the structure using initially 2D seismic data acquired post Tryal Rocks&#x2013;1, then 3D data, indicated that Tryal Rocks&#x2013;1 was drilled within closure, but off crest, and that significant closure existed up-dip. The John Brookes&#x2013;1 location was selected to test this updip potential. The John Brookes&#x2013;1 discovery confirmed the validity of the structural mapping. However, the unexpected nature of the reservoir, interpreted as a well developed turbiditic channel of Birdrong Sandstone age, changed the emphasis from purely structural to a play with structural/stratigraphic potential. An amalgamated turbidite complex model was invoked which infers that the John Brookes&#x2013;1 reservoir represents a confined channel system cut into the underlying substrate. This model explains the results to date, with the John Brookes&#x2013;1 gas reservoir being in direct continuity with the sandstones at Tryal Rocks&#x2013;1. A review of the 3D seismic data across the field and seismic modelling support the stratigraphic model developed from the palynological interpretation. 
