Summary
This study aims to combine a novel global interpretation method, using a relative geological time model and spectral decomposition imaging techniques, into a powerful workflow capable of extracting from seismic data very fine geomorphological features. The workflow was applied to a public domain 3D marine seismic data set covering the Exmouth Sub-basin in Northwestern Australia. The analysis at a sub-seismic scale of horizons stacks allowed the interpretation of complex geo-bodies, which would have remained undetected with classical methods.
Introduction
The Exmouth Sub-basin is characterized by a complex geology made of various stratigraphic unconformities and a dense fault system. For those reasons, the interpretation of such a region with classical methods remains an intensive task, where only a few horizons could be obtained with many assumptions. The novel global approach presented in this paper was applied to the Exmouth Sub-basin dataset to build a full interpreted volume and better resolve geological ambiguities and identify sedimentary features.
Geological settings and data
The 1,000-km² seismic survey HCA2000A 3D covers the Jurassic and the Cretaceous depocentres of the Exmouth Sub-basin. The Exmouth Sub-basin is part of the North Carnarvon Basin, along the West Australia margin. From the late Paleozoic to the Early Jurassic, the basin evolved as a sag basin. The dense fault system in the lower part was developed by rifting during the Jurassic-earliest Cretaceous, associated with the breakup of East Gondwana (Tindale, 1998). Thick Jurassic syn-rift marine sediments were deposited in the new accommodation resulting from the extension. Uplift and erosion to the South of the basin provided a supply of sediments for the Lower Cretaceous sandstones, which prograded across the sub-basin.
The geological features from the Jurassic and Cretaceous periods represent potential targets for exploration. Previous work on this area has shown proven reservoirs in the Barrow Group and Dupuy Sandstone. The Muderong Shale is a regional seal and the Jurassic-Cretaceous faulted parts represent a good structural trap within the Mungaroo.
