Potential Fields for Petroleum Exploration: Salt Walls in the Officer Basin Signature in Aero Magnetic Data

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Potential Fields for Petroleum
Exploration:
Salt Walls in the Officer Basin
Signature in Aero Magnetic
Data

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Location Map: Officer Basin & Yowalga Sub Basin
• Huge Underexplored Basin
• Large Area - Extends from
Western Australia into
South Australia
• Some historic 2D seismic
Coverage
• 500m line spaced magnetic
data (coarse)
• Sparse Gravity data
• Very remote – land access
issues could make further
land seismic surveys
difficult
Yowalga
Sub
Basin

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Location Map: Yowalga Sub Basin
• Intra-Basin Table Hill
Volcanics provide magnetic
signature when ruptured
• Extensive Salt Diapirs in the
South – negative density
contrast in gravity data
• Salt Diapirs, Domes and
Walls can act as
hydrocarbon traps
• Seismic Line T080-007
traverses the Browne Salt
Wall
Seismic line T080-007

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Seismic Line T080-007
Subtle first vertical derivative (1VD) Magnetic
signature from breached Table Hill Volcanics
Salt diapirs are generally well imaged in Seismic reflection Data
In this case the Browne Salt Wall can be seen in the magnetic data because it has
breached a sub horizontal magnetic layer (Table Hill Volcanics)
Browne
Salt Wall
Table Hill Volcanics
Salt
wall?

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Officer Basin – Browne Salt Wall
• The subtle magnetic response from
the breached Table Hill volcanics is
much more apparent in the gridded
1VD magnetic data
• The Browne Salt Wall is visible for 85
Kilometers in the gridded data
• This could provide the means to
target further seismic surveys (salt
wall = possible hydrocarbon trap)
• High resolution magnetic surveys
would improve definition of salt wall

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“blind” Salt wall (has
not breached volcanics)
Table Hill Volcanics
Browne
Salt Wall
Gravity Response – Forward Model Airborne Systems
May not be seen in magnetic
data if volcanics not breached
Low Density salt dome should produce a strong negative
anomaly in airborne gravity and gravity gradiometer surveys

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Conclusions:
• Magnetic data can reveal salt diapirs in basins where they breach or
disturb magnetic units
• Gravity data may reveal “blind” salt diapirs not evident in the magnetic
data (i.e. where they do not breach or disprupt the overlying magnetic
units)
• Both Airborne gravity/gradiometry and magnetic surveys can provide the
means to focus expensive seismic surveys in the right areas
• Further reading
• Salt tectonics in the Officer Basin: implications for trap formation and
petroleum exploration. Anelia Simeonova and Robert Iasky. ASEG
Extended Abstracts 2004(1) 1 - 4
• http://www.publish.csiro.au/paper/ASEG2004ab132
• Using potential field data to map salt distribution in the Western
Officer Basin, Western Australia.
• http://www.publish.csiro.au/?act=view_file&file_id=ASEG2015a
b072.pdf