Structural architecture and basin evaluation of the North West Shelf

Abstract

The WestraliaSPAN 2D regional program extends across all basins of Australia’s North West Shelf (Carnarvon/Roebuck/Browse/Bonaparte basins) and Arafura regions. The survey is designed with long offset and record length (18 sec) acquisition parameters to image the important deep crustal and sub crustal architecture and depositional systems across this complex margin. The regional program provides unique, state-of-the-art depth imaging of deep-basement rift structures of the Westralian Superbasin, as well as the lower crust and Moho. The survey has multiple transects which cross the transition from continental to oceanic crust, that provide insight into the distribution of volcanics and a possible hyper-extended rift margin. An integrated geological and geophysical interpretation encompasses available well, seismic and potential field data. Gravity models were developed to aid in depth conversion and the structural interpretation of the deep crust and Moho. A comprehensive model of basin formation provides the context for regional correlation of tectonostratigraphic packages throughout these linked basin systems, highlighting pre-Jurassic rift basins and their structural controls. While the North West Shelf, Browse and Bonaparte basins are proven and established hydrocarbon provinces, a future step-change in exploration concepts involves an integrated, margin-scale understanding of these basin systems and their potential resources. Collectively, the new dataset and interpretation will aid explorers in understanding the nature and distribution of key petroleum systems elements (reservoir/source/seal) and processes (heatflow, timing of source maturity, expulsion, migration and entrapment).