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Enhancing a Seismic Image After Migration Using Deconvolution
Bancroft, John C. (CREWES) | Guirigay, Thais (CREWES) | Isaac, Helen (CREWES)
Summary The inversion process to recover rock properties is typically approximated with seismic migration that is a transpose process. This transpose process limits the frequency content that should be recovered. The lower and higher frequencies that are lost, can be recovered by following a migration with deconvolution. There is opposition to applying deconvolution after migration, and we review those objections and then present two arguments to validate this proposition. The improvement in resolution is illustrate using a simple single trace spiking deconvolution. We propose that additional improvements can be achieved using a more sophisticated deconvolution that incorporates the dip of an event.
Summary Dip-limited migrations are utilized in practice for the purpose of either decreasing the computational cost (e.g., Kirchhoff migration) or suppressing noise (e.g., Kirchhoff and F-K migration). Dip-limited F-K migration is a common Stolt F-K migration with an embedded dip filter; while the dip-limited Kirchhoff migration is implemented by limiting the aperture of migration operators. Either of these methods will cause a dip-filtering action and result in a dip-limited output section. However, there are distinctions between the effects of dip-limited Kirchhoff and F-K migration. Dip-limited F-K migration has an exact dip-filtering effect on the migrated section and can remove all the energy above a defined dip limit, whereas the diplimited Kirchhoff migration will generate additional artifacts when the dip limit is less than the maximum dip on the desired output section. These artifacts are caused by the endpoints of the migration operators.
Summary The inversion of seismic reflectivity data may be approximated by a Kirchhoff migration process. The theory linking these processes is accomplished with cartoon descriptions to visualize the development and simplifying assumptions. The description starts with deconvolution theory that is extended to include time varying wavelets that are modified to become time varying diffractions. Introduction The term inversion is used in a number of different applications in geophysics such as: 1. Estimating source and receiver statics from crosscorrelation statics (trims) 2. Deconvolution 3. Converting seismic data to a geological image. These applications often use the mathematics of least squares inversion, where observations are processed to extract the best estimates of parameters, i.e. over-determined data where we have many more equations than variables.
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Inversion (0.71)
The input data can be borehole VSP data, or vertical locations of the CSP gather and the source-receiver receiver arrays from marine data.