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Briguglio D.,Monash University | Hall M.,Monash University | Keetley J.,3D GEO Pty Ltd.
Australian Journal of Earth Sciences | Year: 2015

The dominant control on the (transition between) depositional settings of the Crayfish Group of the Otway Basin in Victoria, Australia has been determined. The study first involved seismic mapping of six stratigraphic units within the Early Cretaceous, continental Crayfish Group. The resulting 3D structural model was used to identify major Early Cretaceous depocentres, and to determine which Crayfish Group sediments are restricted to individual rift depocentres and which are more widespread as a result of inter-connectivity of the basin. Five structural cross-sections were then constructed across each major depocentre of the basin; these were balanced and restored, and missing section estimated, in order to test the validity of the structural interpretations. This also enabled analysis of differing extensional rates within each depocentre and the calculation of the cumulative displacement of each major bounding fault. Results show that displacement rate, growth and linkage of the faults, as well as the amount of subsidence within the depocentres, had a significant effect on the distribution and development of the major facies within the Crayfish Group. The Casterton Formation and Sawpit Shale equivalent/McEachern Sandstone were restricted to rapidly subsiding, structurally controlled depocentres in the west, while the succeeding Sawpit Sandstone equivalent was deposited within the same depocentres, across the intervening structural highs and in the eastern part of the basin where depocentres had just begun to form. The Pretty Hill Formation shows a similar distribution pattern, while the overlying fine-grained Laira Formation also drapes structural highs but is replaced in the east by coarser-grained sediments of the upper Pretty Hill Formation. Extension was locally up to 21% in the central Otway Basin but was much less in the eastern Otway Basin. © 2015 Geological Society of Australia.

This paper describes a process by which seismic related properties from 2D seismic lines are extracted and a 3D property model is constructed. This interpretation workflow is then tested and described on a pilot area in the northern portion of the onshore Gippsland Basin, Australia. The primary reservoir sands in this region appear to be deposited in a channel recognised on 2D seismic lines. Seismic inversion was performed on each 2D seismic line to differentiate between geological bodies, and these inverted seismic sections were fed into a 3D model in an attempt to track the sand filled channels and seals, based on the seismic-derived attributes. The sealing sequence is characterised by distinctive log/seismic properties, which were modelled in 3D, and attempts are made to discuss seal potential in terms of geometry and integrity. © ASEG 2011.

Nourollah H.,3D GEO Pty Ltd. | Keetley J.,3D GEO Pty Ltd. | O'Brien G.,DPI Victoria
Leading Edge (Tulsa, OK) | Year: 2010

Chimneys are vertical chaotic disturbances in seismic sections related to the propagation of fluids (especially gas) through fissures and fractures in rocks. They can be indicative of mud diapirism, active gas seepage, migration pathways or hydrocarbon reservoirs themselves (Aminzadeh et al., 2002). © 2010 Society of Exploration Geophysicists.

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