The Pedirka Basin is a Permo-Carboniferous basin.
It is an intracratonic basin unconformably overlying the SE Amadeus Basin and western Warburton Basin which were deformed during the Alice Springs and possibly Delamerian Orogenies.
|Area in South Australia||27 000 km2 (10 420 sq miles)|
|Depth to target zone||600 - >2000m|
|Thickness||Up to 1500m|
|Hydrocarbon shows||Minor fluorescence, trace gas|
|First commercial discovery||None|
|Undiscovered resources (50%)||Not determined|
|Reservoirs||Non marine sandstone|
|Regional structure||Faulted anticlines|
|Seals||Non-marine shale, siltstone|
|Source rocks||Non-marine shale, coal|
|Number of wells||10|
Seismic line km
The Pedirka Basin has an area of 150 000 km2, approximately one fifth of which is in South Australia and the remainder in the Northern Territory, possibly extending from there into Queensland. It is an intracratonic basin unconformably overlying the SE Amadeus Basin and western Warburton Basin which were deformed during the Alice Springs and possibly Delamerian Orogenies.
A final NW–SE compressional phase of the Alice Springs Orogeny in the Mid to Late Carboniferous initiated deposition in the Pedirka Basin and created thrust faults such as occur at Mt Hammersley. Permo-Carboniferous sediments were subsequently deposited in a tectonically quiescent sag phase. In South Australia the Permian is entirely overlain by up to 2500 m of Triassic to Late Cretaceous sediments of the Simpson and Eromanga basins.
The sediments were subsequently uplifted and eroded during two major compressional episodes during the late Early to Late Permian and during the Tertiary.
The Pedirka Basin is currently covered by seven PEL applications and PEL 288.
Two Permo-Carboniferous formations are present in the subsurface and crop out on the basin margin in the Northern Territory. The lowermost unit (Crown Point Formation) consists of fluvioglacial and glaciolacustrine sediments. The overlying Purni Formation was deposited in a floodplain environment containing meandering river systems and extensive swamps in which coal developed.
Three facies suites are distinguishable on the basis of relative proportions of sandstone, shale and coal. Equivalents of the Stuart Range and Mt Toondina formations of the Arckaringa Basin are interpreted in Mt Hammersley 1.
The Purni Formation contains extensive coal-rich organic shale which appears to be both oil and gas-prone. It contains up to 4% dispersed organic matter, with vitrinite and exinite macerals present in moderate abundance. Data from Dalmatia 1 and Mt Hammersley 1 indicate poor to good source potential for oil in the Purni Formation.
In many areas geothermal gradients are too low for the sediments to have generated significant quantities of hydrocarbons. In South Australia thermal maturity appears to increase from west to east with VR approaching 0.9% maximum, equivalent to peak oil generation.
Early to mid Tertiary compressive deformation reactivated older structures and formed anticlines and faulted anticlinal traps. Other potential plays are onlap, unconformity and pinchout traps.
There is no estimate of undiscovered resources.
There are no current projects.
Licence activity in the previous year is detailed in the ‘Exploration and development’ section of this USB, and Figure 5 shows the licence status at the time of publication. Use this link for further information on holders of petroleum tenements in South Australia.
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