Perth Basin

Location Map

Offshore Perth Basin in relation to Australia

Map of South West Australia showing Perth Basin in relation to Australia
© Geoscience Australia

Basin Details and Geological Overview

The Perth Basin is a north to north-northwest trending, onshore and offshore sedimentary basin extending about 1300km along the southwestern margin of the Australian continent. This is a large (172 300km2), structurally complex basin that formed during the separation of Australia and Greater India in the Permian to Early Cretaceous. It includes a significant onshore component and extends offshore to the edge of continental crust in water depths of up to 4500m.

The structural architecture of the Perth Basin is the product of oblique rifting during the Permian, Late Triassic to Early Jurassic and Middle Jurassic to Early Cretaceous, superimposed over pre-existing basement terrains. Extension during the Permian produced a series of deep (up to 15km), north-south trending rift basins (Bunbury Trough and Dandaragan Trough) along the western margin of the Yilgarn Craton. The Abrolhos Sub-basin represents a northwestern branch of the Permian rift system formed along the southwestern margin of the Northampton Complex, which is separated from the Dandaragan Trough by an intra-basin high represented by the Beagle Ridge, Dongara Terrace and Greenough Shelf. The Houtman Sub-basin is a major depocentre for Triassic and Jurassic sedimentary rocks that formed as a westward thickening sag basin across a hinge zone during the Middle Triassic to Middle Jurassic, and was extensively faulted during Late Jurassic to Early Cretaceous rifting. The Vlaming Sub-basin is the major Middle Jurassic to Early Cretaceous rift basin in the Perth Basin and is characterised along its northern extent by a very large and deep half graben that dips to the west. The footwall block of this half graben consists of a series of shallow tilted fault blocks containing mainly Permian and older strata from the Edward's Island Block.

Breakup during the Early Cretaceous (Valanginian) was associated with widespread inversion, erosion, strike-slip tectonics and volcanism, which significantly modified the structural architecture of the Perth Basin. Major structural elements associated with breakup tectonism include an area of inverted Permian half graben in the Turtle Dove Ridge and the Zeewyck Sub-basin which formed in a zone of strike-slip faulting along the Turtle Dove Transfer.

Summary of exploration status and petroleum system elements

PERTH BASIN
State

Western Australia

Area (km2)

172 300

Water depth (m)

0-4500

Maximum thickness (m)

15 000

Age range

Permian to Cainozoic.

Basin Type

Polyhistory: intracratonic rift, strike-slip, thermal sag, divergent passive margin.

Basin Overlies/adjoins

Southern Carnarvon Basin, Yilgarn Craton, Northampton Complex, Leeuwin Complex.

Underlies -
Subdivisions

Houtman, Abrolhos, Vlaming, Zeewyck and Coolcalalaya Sub-basins, Bunbury, Dandaragan, Coomallo and Beermulah troughs, various terraces, shelves and ridges.

Other  
Exploration Status

Submature (northern onshore), immature to frontier (other areas).

Wells

32 offshore, >200 onshore (Dec 2003).

Seismic line-km

Not determined - regional to field scale 2D.

Discoveries

Onshore: 4 oil accumulations, 6 gas accumulations and 1 oil and gas accumulation; 6 gas fields, 4 oil fields, 2 oil and gas fields.
Offshore: Oil field on the Beagle Ridge (Cliff Head), oil accumulation in the Vlaming Sub-basin (Gage Roads 1), gas accumulation in the Vlaming Sub-basin (Marri 1).

Shows (offshore)

Vlaming Sub-basin: Oil at Araucaria 1, oil and gas at Gage Roads 2.
Houtman Sub-basin: Oil and gas at Houtman 1.

HC evidence

Evidence for seepage (several SAR and ALF anomalies).

Geology Source(s)

Permian coals and shales (gas), Lower Triassic shales (oil), Jurassic coals (oil and gas), Jurassic shales (oil and gas), Lower Cretaceous shales (oil).

Reservoirs

Permian shales, Lower Triassic shales, Middle Jurassic shales, Lower Cretaceous shales.

Trap types

Tilted fault blocks, compressional rollovers, anticlines, stratigraphic and combined structural/stratigraphic.

Palaeogeographic summary

Permian: fluvio-glacial, shallow marine (several transgressions in north), coal swamps (particularly in the south), alluvial fan deltas;
Triassic: shallow marine in north, fluvial and coal swamps in south, becoming fluvial throughout;
Jurassic: fluvio-lacustrine, shallow marine, then major uplift of the Yilgarn Craton led to deposition of very thick fluvial sandstones;
Cretaceous: some early volcanism in the south, but mainly shallow marine throughout;
Cainozoic: shallow marine to continental onshore but little deposition, shallow to deep marine clastic and carbonate deposition offshore.

Timing Oil generation

Late Triassic to Middle Jurassic (onshore)
Middle-Late Jurassic (offshore north)
Late Jurassic-Early Cretaceous (offshore south)

Gas generation

Late Triassic to Middle Jurassic peak, generation through Cainozoic (onshore) - Dandaragan gas generation later than oil

Trap formation

Permian (structural and stratigraphic)
Late Triassic to Early Cretaceous (structural)
Early Cretaceous (structural)

Other key times

Main structural events include Permian rifting, Late Triassic-Early Jurassic rifting, Middle Jurassic-Early Cretaceous rifting and Early Cretaceous (Valanginian) continental breakup.

Other important information

All petroleum production to date in the Perth Basin is from the onshore (Gondwanan) petroleum system.

For more web information

Western Australia Department of Industry and Resources

ProvExplorer

 

Stratigraphy

 

The stratigraphy and petroleum system elements of the Perth Basin developed during the tectonic evolution of the basin and vary significantly from north to south. Initial rifting established a series of Permian to Early Triassic depocentres for fluvial and marine siliciclastics with minor carbonates and coals in the north, while in the south fluvial siliciclastics and coals dominated. These Permian- and Early Triassic-age rift-sag deposits are associated with the major petroleum system in the north Perth Basin, particularly the Kockatea Shale which forms an important oil source rock and regional seal to underlying reservoirs.

A second phase of rifting in the Late Triassic and Early Jurassic was associated with widespread fluvial and deltaic deposits, including a thick succession of siliciclastics and coals (Cattamarra Coal Measures), which are overlain by Middle Jurassic marine shales (Cadda Formation) in the north Perth Basin. These Early to Middle Jurassic strata form a second proven petroleum system in the north Perth Basin. The final rift and breakup phase in the Middle Jurassic to Early Cretaceous was associated with deposition of fluvial and marine siliciclastics (Yarragadee Formation, Parmelia Group and Warnbro Group), which form the main petroleum system in the Vlaming Sub-basin.

It is uncertain which petroleum system elements are associated with the Zeewyck Sub-basin. However, it may contain Middle Jurassic to Early Cretaceous age source rocks. Late Cretaceous and Tertiary sedimentation has occurred under stable passive margin conditions and produced a thin cover of predominantly marine carbonates. Potential traps include tilted fault blocks, anticlines, compressional rollovers and structural/stratigraphic traps.

Regional Cross-sections

Seven regional cross-sections have been selected to provide examples of the structural architecture of the Perth Basin. Examples from the onshore Perth Basin are provided courtesy of the Geological Survey of Western Australia.

Perth Basin Location Map showing where each of the Regional Cross Sections have been taken

Figure 3 - Map showing the locations of cross-sections in the
Perth Basin
© Geoscience Australia

Petroleum Systems and Hydrocarbon Potential

Petroleum exploration

Northern Perth Basin Well Locations

Figure 12 - Map of offshore wells
and onshore fields in the
Northern Perth Basin
© Geoscience Australia

The exploration status of the Perth Basin varies from submature in the northern onshore area and immature to frontier in most offshore areas.

Initial exploration for hydrocarbons in the Perth Basin began in the late 1940s with an onshore field survey and evaluation of water drilling commissioned by Ampol and Richfield Oil companies and gravity surveys by the Bureau of Mineral Resources. The onshore portion is extensively explored with over 200 wells drilled.

Offshore exploration began in 1965. The offshore portion is under-explored with only 32 wells drilled (Dec 2003). Seismic coverage over the offshore Perth Basin varies in density and seismic quality ranges from poor in the older surveys to good in more recent data. Ten offshore exploration permits are currently active (WA-226-P, WA-286-P, WA-325-P, WA-326-P, WA-327-P, WA-328-P, WA-349-P, WA-336-P, WA-339-P and WA-337-P), all of which are in the Abrolhos and Houtman Sub-basins.

To date, twenty-six petroleum accumulations have been discovered in the Perth Basin, thirteen of which have proven to be commercial. Most discoveries are from the onshore north Perth Basin. The first discovery was the Yardarino gas field in 1964, while the most significant discovery has been the Dongara oil and gas field (initial reserves of 15.3 billion cubic metres of gas and 10 million barrels of oil).

Hydrocarbon production has occurred from Dongara (gas and some oil), Yardarino (gas and some oil), Beharra Springs (gas), Mondarra (gas), Mt Horner (oil), Woodada (gas), Walyering (gas) and North Yardanogo (oil) in the onshore north Perth Basin. Of these, Dongara, Beharra Springs, Woodada and Mt Horner are still producing.

Southern Perth Basin Well Locations

Figure 13 - Map of offshore wells
and onshore fields in the Southern
Perth Basin
© Geoscience Australia

Oil and gas has been produced from Jurassic coals within the Cattamarra Coal Measures, from Triassic sandstones within and underlying the Kockatea Shale and from the Late Permian Dongara Sandstone and Wagina Sandstone.

Commercial quantities of gas have also produced from the Permian Carynginia Formation and Irwin River Coal Measures. Important recent discoveries in the onshore Perth Basin include Beharra Springs North (gas), Hovea (oil), Jingemia (oil) and Eremia (oil).

In the onshore south Perth Basin, Gingin 1 has produced gas but is now depleted. Whicher Range contains 46.4 billion cubic metres of gas that was originally considered uneconomical, but is currently being tested to see if economic gas flow rates can be sustained.

Limited exploration in the offshore Perth Basin has identified three discoveries. These include a non-commercial gas accumulation in the Lower Carnac Member at Marri 1 (Vlaming Sub-basin) and a non-commercial oil accumulation in the Gage Sandstone at Gage Roads 1 (Vlaming Sub-basin).

The most significant offshore discovery to date is the Cliff Head oil field, located on the Beagle Ridge just east of the Abrolhos Sub-basin. Cliff Head contains estimated recoverable reserves of 20-30 million barrels of oil within Permian reservoirs that are sealed by the Kockatea Shale. The Cliff Head discovery has stimulated renewed interest in exploration for oil in the offshore Perth Basin.

Key References

Author(s) Year Title
Blyth, C.I. 1994 Beagle seismic survey interpretation report WA-22-P (North). Woodside Offshore Petroleum, PSLA 92/30 (unpublished)
Cadman, S.J., Pain, L. and Vuclovic, V. 1994 Perth Basin, WA. Australian Petroleum Accumulations Report 10, Bureau of Resources Sciences, Canberra
Crostella, A. 1995 An evaluation of the hydrocarbon potential of the onshore northern Perth Basin, Western Australia. Western Australia Geological Survey, Report 43, 67p
Crostella, A. 2001 Geology and petroleum potential of the Abrolhos Sub-basin, Western Australia. Western Australia Geological Survey, Report 75, 57p
Crostella, A. and Backhouse, J. 2000 Geology and petroleum exploration of the central and southern Perth Basin, Western Australia. Western Australia Geological Survey, Report 57, 85p
Jones, N.T. and Hall, A.D. 2002 The Cliff Head Oil Discovery - Offshore Perth Basin. The Sedimentary Basins of Western Australia. Proceedings PESA Symposium, Perth, 901-909
Kempton, R.H., Liu, K., Boreham, C., Bradshaw, B.E., Eadington, P.J. and Passmore, V. 2002 Oil migration and accumulation in the offshore Perth Basin, Western Australia. CSIRO Confidential Report 02-005 to Geoscience Australia, 71p
Marshall, J.F., Lee, C.S., Ramsey, D.C. and Moore, A.M.G. 1989 Tectonic controls on sedimentation and maturation in the offshore north Perth Basin. The Australian Petroleum Production & Exploration Association (APEA) Journal, 29 (1), 450-465
Mory, A.J. and Iasky, R.P. 1996 Stratigraphy and structure of the onshore northern Perth Basin. Western Australia Geological Survey, Report 46
Owad-Jones, D. and Ellis, G. 2000 Western Australia atlas of petroleum fields, onshore Perth Basin. Petroleum Division, Department of Minerals and Energy Western Australia, Volume 1, 114p
Quaife, R., Rosser, J. and Pagnozzi, S. 1994 The structural architecture and stratigraphy of the offshore northern Perth Basin. IN: The Sedimentary Basins of Western Australia (Edited by Purcell, P.G. and Purcell, R.R.). Proceedings of the West Australian Basins Symposium, Western Australia PESA, Perth, 1994, 811-822
Song, T. and Cawood, P.A. 1999 Multistage deformation of linked fault systems in extensional regions; an example from the northern Perth Basin, Western Australia. Australian Journal of Earth Sciences. 46; 6, Pages 897-903
Song, T and Cawood, P.A. 2000 Structural styles in the Perth Basin associated with the Mesozoic break-up of greater India and Australia. Tectonophysics. Vol. 317, Issues: 1-2, Pp 55-72
Stagg, H.H.J, Willcox, J.B., Symonds, P.A, OBrien, G.W., Colwell, J.B., Hill, P.J., Lee, C.S., Moore, A.M.G. and Struckmeyer, H.I.M. 1999 Architecture and evolution of the Australian continental margin. AGSO Journal of Australian Geology and Geophysics. 17; 5-6, Pages 17-33. 1999