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From the sonic log, assuming constant density, normal incidence, no multiples
or reverberations and no absorption, a synthetic seismic trace was created.
The reflection coefficients for the trace were simply computed with the
recursion:
| |
(180) |
where RCi is the reflection coefficient at the ith interface and
V and represent velocity and density respectively. The density
was assumed to be constant. The depth-to-time conversion was simply done by
integrating the vertical travel time
| |
(181) |
where represents the thickness of the j-th layer. In
this case the layer thickness was kept constant at 10 feet.
Once converted to time, the reflectivity series was interpolated
to a constant time-sampling interval using an 8-point sinc interpolator and
convolved with a Ricker wavelet of 60 Hz peak frequency. The right panel of
Figure shows the resulting synthetic trace with time zero
corresponding to the shallowest depth in the log segment (3600 feet).
input
Figure 1 Left panel: Sub-sampled sonic log used to
generate the synthetic trace on the right panel. The zero of the seismic trace
corresponds to the initial depth of the log.
Next: Velocity Inversion
Up: R. Clapp: STANFORD EXPLORATION
Previous: Preprocessing of the well
Stanford Exploration Project
11/11/2002