Subsidence and thermal history modelling: new insights into hydrocarbon expulsion and multiple petroleum systems in the Petrel Sub-basin, Bonaparte Basin  

Authors / CoAuthors

Kennard, J.M. | Deighton, I. | Edwards, D.S. | Boreham, C.J. | Barrett, A.G.

Abstract

Subsidence and thermal history analysis of 24 wells and seismic-defined depocentre sites has been undertaken to investigate the generation and expulsion history of the Early Carboniferous and Permian petroleum systems in the Petrel Sub-basin. Modelled oil and gas expulsion from postulated oil-prone source units within the Lower Carboniferous Milligans Formation is restricted to two offshore depocentres immediately north and south of the Turtle-Barnett High. Expulsion commenced in the Late Carboniferous, reached its peak in the Early Permian, and minor expulsion continued throughout the Permian and Early-Mid Triassic prior to the onset of regional uplift associated with the Late Triassic Fitzroy Movement. Limited gas expulsion is also modelled in the onshore Carlton Sub-basin, and although this unit is sufficiently mature in this area to have generated oil, the models suggest that generated volumes are insufficient for expulsion of oil. Modelled oil and gas expulsion from mudstones and coaly mudstones of the Lower Permian Keyling Formation is restricted to the central and outer portions of the Petrel Deep. Expulsion from the outer Petrel Deep occurred in the Late Permian - Early Triassic, and expulsion from the central Petrel Deep commenced and peaked in the Early Triassic, with subsequent phases of minor expulsion in the Late Triassic - Cretaceous. Oil expelled from these source units may have migrated to pre-Fitzroy Movement structures and stratigraphic traps within and on the flanks of the Petrel Deep, but to date the only possible indication of such an oil charge are low confidence SAR slick anomalies east and southeast of the Petrel Field. Modelled gas expulsion from the Upper Permian Hyland Bay Formation is limited to the outboard limits of the Petrel Sub-basin, and occurred in the Jurassic-Cretaceous with peak expulsion in the mid-late Cretaceous. This unit is considered too lean to expel significant quantities of oil. These expulsion models are integrated with the known distribution of hydrocarbon accumulations, shows and SAR anomalies to map the extent of the petroleum systems in the Petrel Sub-basin. These maps can then be used to assess the likely source(s) of the recent Blacktip-1 gas discovery, and to evaluate the charge potential of traps within the sub-basin, including those within the 2002 offshore acreage release areas.

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nonGeographicDataset

eCat Id

39801

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Keywords

• External PublicationConference Paper

( Theme )

• petroleum geology

( Theme )

• hydrocarbons

( Theme )

• organic geochemistry

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2002-01-01T00:00:00

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Australian Government Security ClassificationSystem    

Classification - unclassified

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Creative Commons Attribution 4.0 International Licence    

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unknown

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geoscientificInformation

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Unknown

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Extents

[-15.5, -11.0, 127.0, 130.5]

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