Using Magnetic and Gravity Data in Basin and Coal-related Geology Studies

Geophysical data plays an important role in basin studies. In particular, gravity and magnetic data can provide a cost-effective means to assist in interpreting basin to lease-scale structural geology and depth to basement studies.

Magnetite is a very minor constituent of sediments, which makes magnetic data valuable for determining the distribution of magnetic sources within the sediments, ranging from heavy minerals deposits (e.g. fans) to basalts.

Gravity and magnetic data provide vital information on the structure and composition of the basin basement. Major basement structures can be interpreted from the presence of consistent discontinuities and/or pattern breaks in the gravity and magnetic data. They permit the determination and definition of structural breaks in areas where the basement composition is not known.

Where the source of the gravity and magnetic signal is very deep and not resolvable by common data processing algorithms, enhancement techniques can be applied to reveal information about the geometry and structure of the basement at depth.

SRK strives to use all available data sets to provide an up-to-date structural interpretation. The image above illustrates the combination of detailed and regional surveys with other information, such as drill hole data and photo/satellite interpretation to provide a structural interpretation.

SRK’s state-of-the-art depth to basement interpretation uses the 2D Werner Deconvolution magnetic inversion algorithm, 3D UBC-GIF magnetic inversion technique and individual 2.5D forward modelling of gravity and magnetic profile data. Except for the seismic data, interpreting the results provides an alternative check on the basement depth and thickness of the target stratigraphy. Companies have discovered that using these tools can be most effective in reducing the costs of new seismic acquisitions.

These geophysical skills complement our structural and coal resource geology capabilities.

Bin Guo: bguo@srk.com.au
Pat Hillsdon: phillsdon@srk.com.au
 

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