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Line 28: + + − − [[file:seismic-inversion_fig4.png|thumb|{{figure number|4}}A schematic diagram of a river channel zone. Copyright: the Taber area of southern Alberta. The 3-D survey was done in the area outlined by the rectangle in the center of the map. (Courtesy of Western Geophysical.]]
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The second type of inversion, which is more recent than the band-limited method, involves producing a “blocky” output rather than a band-limited output. There are several methods that produce this type of output, and they are sometimes referred to as ''sparse-spike'' or ''model-based methods''. These methods work by producing a forward model that best reproduces the seismic data when converted to synthetic form (that is, when the reflection coefficients are convolved with the wavelet). This method involves starting with a simple “guess” of this model and changing this guess iteratively until the error between the model and the observed seismic data is minimized (see “Forward Modeling of Seismic Data”). The results of doing such a model-based inversion are shown in [[:file:seismic-inversion_fig3.png|Figure 3]] for the same traces shown in [[:file:seismic-inversion_fig2.png|Figure 2]]. Notice that the carbonate reef is visible, and looks like the blocked version of the log.
The second type of inversion, which is more recent than the band-limited method, involves producing a “blocky” output rather than a band-limited output. There are several methods that produce this type of output, and they are sometimes referred to as ''sparse-spike'' or ''model-based methods''. These methods work by producing a forward model that best reproduces the seismic data when converted to synthetic form (that is, when the reflection coefficients are convolved with the wavelet). This method involves starting with a simple “guess” of this model and changing this guess iteratively until the error between the model and the observed seismic data is minimized (see “Forward Modeling of Seismic Data”). The results of doing such a model-based inversion are shown in [[:file:seismic-inversion_fig3.png|Figure 3]] for the same traces shown in [[:file:seismic-inversion_fig2.png|Figure 2]]. Notice that the carbonate reef is visible, and looks like the blocked version of the log.
[[file:seismic-inversion_fig4.png|thumb|{{figure number|4}}A schematic diagram of a river channel zone. Copyright: the Taber area of southern Alberta. The 3-D survey was done in the area outlined by the rectangle in the center of the map. (Courtesy of Western Geophysical.]]
==Three-dimensional case study==
==Three-dimensional case study==
[[file:seismic-inversion_fig5.png|left|thumb|{{figure number|5}}The model-based inversion of the line through the river channel system of Figure 4. Copyright: Western Geophysical.]]
[[file:seismic-inversion_fig5.png|left|thumb|{{figure number|5}}The model-based inversion of the line through the river channel system of Figure 4. Copyright: Western Geophysical.]]