A problem encountered in residual statics estimation is the coupling of
velocity and statics. Changing the medium wavelength statics (0.5 to 3
spread length) will change the medium wavelength stacking velocity.
The classic approach to this problem is to repeat the velocity analysis
and residual static estimation sequence. Incorporating rapid lateral
variation in the initial stacking velocity will prevent the medium wavelength
estimation by residual statics. The undesirable rapid velocity variation
is locked into the final velocity field. I used the strategy described on
page 236 of Mike Cox' statics book (Cox, 1999). I ran
velocity analysis and statics twice. On the first
iteration, I used single function velocity function for moveout before
residual static estimation. If the line was longer I might have run
a coarsely sampled set of velocity analyzes. After the first
pass of residual statics, I ran velocity analysis every 48 CDPs (2640 ft
or 0.5 spreadlength). I did not notice improvement when I compared the
stack with the first pass of residual statics and the velocity field from
the 48 CDP velocity analysis with the results after two passes of residual
statics. The next sections step through the velocity analysis and residual
static processes.
Open Data/Open Source: Seismic Unix scripts to process a 2D land line