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As a simple example of the methodology, we started from a single CMP
gather (Figure data).
We then scanned over velocities calculating semblance
and instantaneous stack energy (Figure rmspicks).
We started with an initial RMS velocity function
by picking the maximum semblance
within a fairway. We used the corresponding instantaneous stack energy
for our weighting function, .
data
Figure 1 Input CMP gather from the Gulf
of Mexico.

 
rmspicks
Figure 2 Two different approaches to picking starting RMS and weighting functions. Both start by scanning over velocity and
then picking maximum amplitude within a fairway. To avoid edge problems
early and late time velocities are predetermined.
The left frame shows a semblance scan and the resulting RMS function;
the right panel, same information for instantaneous stack energy
We applied fitting goals (7) and (8) to the picked
RMS function and obtained Figure a smooth,
reasonable velocity function.
scaleresiduals
Figure 3 Estimated interval
velocity obtained from fitting goals (7) and (8).

 
Next: Block Models
Up: Velocity estimation: Clapp, et
Previous: BASIC IDEA
Stanford Exploration Project
7/6/1998