Authors / CoAuthors
Borissova, I. | Nicholson, C.J. | Krassay, A.A. | Newmann, V. | Di Primio, R.
Abstract
The Mentelle Basin is a large (36 400 m2) frontier basin lying less than 100 km to the west of the oil and gas producing Perth Basin. The basin was formed during Jurassic extension which preceded the breakup between Australia and Greater India in the Valanginian. The breakup was accompanied by significant volcanism with extensive lava flows overlying the Valanginian unconformity. The Mentelle Basin comprises two structurally different depocentres. The eastern depocentre lying in shallow water (less than 500 m) is a large complex half-graben with up to 8 km of sediments, most of which are synrift section. The Western Mentelle depocentre lies between 2000 to 3300 m water depths and contains up to 7 km synrift and 2.5 km postrift section. The Mentelle Basin has never been drilled. Seismo-stratigraphic correlations are made to the DSDP well 258 on the Naturaliste Plateau and to the exploration wells in the Southern Vlaming Sub-basin. However direct correlations are possible only for the Late Cretaceous to recent part of the section. Recent Geoscience Australia studies involving structural restoration of the margin have shown that major tectonic and accommodation cycles are the same for both basins. The ages of the synrift sequences in the Mentelle basin therefore have been interpreted using the new Vlaming Sub-basin tectonostratigraphic framework. Seismic facies analysis was then used to define potential source rock intervals and correlate them to the known source rocks in the Vlaming Sub-basin. To test petroleum potential of this frontier basin 2D burial history analysis has been performed for the three regional lines. For each line three different scenarios with varying source rock characteristics reflecting end member possibilities have been explored. The potential effect of heat flow variations and intrusive volcanics on the maturation history have also been assessed. The modelling results suggest that source rocks in the deepest part of the synrift section are overmature, while uppermost Berriasian source rocks are immature. Source rocks that are currently within the maturation window are Middle Jurassic to Early Cretaceous shaly and coaly intervals, which commenced generation in the Late Jurassic. The erosion of significant sedimentary thickness in the Eastern Mentelle during continental breakup slowed down and in some cases stopped hydrocarbon generation. As this part of the basin has less that 1 km of postrift section only source rocks with sufficient overburden are still generating. In the Western Mentelle the same source rocks are buried much deeper and continued to generate throughout the Tertiary and up to the present. In the Eastern Mentelle oil generation and migration was roughly synchronous with the development of most structures whereas in the western Mentelle more source rock intervals continued generating after the major structuring. The main risk in the Mentelle Basin is the presence of good quality seals at the right stratigraphic level. Existing seismic coverage is insufficient for detailed structural interpretation needed to define potential traps. Provided suitable structures are found in the Mentelle Basin it may have similar petroleum potential to the Vlaming Sub-basin.
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nonGeographicDataset
eCat Id
65628
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- External Publication
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- hydrocarbons
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- petroleum exploration
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- petroleum reserves
- ( Theme )
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- petroleum geology
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2008-01-23T00:00:00
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