Authors / CoAuthors
Drummond, B.J. | Hobbs, R.W. | Goleby, B.R.
Abstract
Most crustal-scale seismic reflection surveys use single profiles, and are an attempt to create two-dimensional images of three-dimensional structures. CMP data are stacked and migrated assuming that the seismic energy comes from within the plane of the section. However, three-dimensional topography on an interface results in out-of-plane reflected energy coming into the plane of the section, and energy from the plane of the section being lost from the plane of the section. Interfaces with low to moderate relief image as a zone of reflections in which the top of the zone reproduces the shape of the interface within the plane of the reflector fairly accurately, and energy lower in the zone of reflections is from out of the plane. However, if the relief on the interface is significant, reflections from shallower levels of the interface out of the plane of the section can arrive before those from deeper parts of the interface in the plane of the section. This makes interpreting both the position of the interface in the plane of the section and the amount of relief on the interface difficult. Three-dimensional topography on the interface out of the plane of the section generates more diffractions than does two dimensional topography. The amount and nature of diffracted energy in stacked data is a qualitative indicator of structure in and out of the plane of the section. For a synthetic three-dimensional interface with relief ranging over a number of wavelengths, reflection amplitudes up to twice the primary reflection strength were observed; destructive interference produced very weak reflections elsewhere. The absolute amplitude of the strongest reflections is therefore a poor indicator of impedance contrast for reflectors with significant three-dimensional topography.
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nonGeographicDataset
eCat Id
41556
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Keywords
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- External PublicationAbstract
- ( Theme )
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- seismic sections
- ( Theme )
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- seismics
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2003-01-01T00:00:00
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