Using potential field data for petroleum exploration targeting, Amadeus Basin, Australia
Mike Dentith 1 3 Duncan Cowan 21 Centre for Petroleum Geoscience & CO2 Sequestration, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
2 Cowan Geodata Services, 12 Edna Road, Dalkeith, WA 6009, Australia.
3 Corresponding author. Email: michael.dentith@uwa.edu.au
Exploration Geophysics 42(3) 190-198 https://doi.org/10.1071/EG10018
Submitted: 14 July 2010 Accepted: 15 May 2011 Published: 2 September 2011
Abstract
The Amadeus Basin, a large Proterozoic basin located in central Australia, is one of the least explored onshore petroleum-bearing basins with proven reserves in Australia. The size and remoteness of the Amadeus Basin makes ground exploration expensive so this study uses aerogravity and aeromagnetic data to assess petroleum prospectivity.
In the western part of the Amadeus Basin the Gillen Petroleum System is considered most significant; this system has the important characteristic that the source in the Bitter Springs Formation is stratigraphically higher than the potential reservoirs within the Dean/Heavitree Quartzite. Thin skinned deformation is expected at the source level and above, with detachments at evaporitic horizons, but deformation of the reservoir is expected to be thick-skinned. This model can form the basis for predicting potential field responses. The most prospective areas are where: (i) gravity suggests basement (and reservoir) is shallow; (ii) magnetics maps fold-thrust complexes (structural trap); and (iii) these features occur adjacent to gravity lows, indicative of significant thicknesses of basin fill (source at depth and below reservoir). Faults at the margins of the depocentre (mapped using magnetic data) provide a possible migration path for the hydrocarbons.
Favourable scenarios for younger petroleum systems are antiforms in fold-thrust complexes in units assigned to the Boord Formation and younger units. The juxtaposition of these structures with depocentres suggested by negative gravity anomalies constitutes a favourable exploration scenario.
Regardless of specific exploration targets, this study demonstrates that airborne gravity and magnetic data are capable of resolving intra-basin structures in sufficient detail to allow prospective areas to be identified and for follow-up seismic surveys to be reliably planned.
Key words: Amadeus Basin, aerogravity, aeromagnetics, petroleum exploration, Western Australia.
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