NAME

Kirch_2d_depth - Kirchhoff 2D migration


SYNOPSIS

Kirch_2d_depth <in.H >out.H tfile=tfile.H pars


INPUT PARAMETERS

stdin - sepfile
    File for input seismic traces (must be a sep3d file)
stdout - sepfile
    File for common offset migration output  (  sep regular cube)
ttfile - sepfile
   File for input traveltime tables. First axis is Z, second axis X, third
    axis is regular spaced source locations. If not provided will be
   calculated.
velfile - sepfile
   Velocity file (only needed if travel time file not provided).
dxm - float
   [d3 of grid] Sampling interval of input midpoints
fzo - float
  z-coordinate of first point in output trace
dzo - float
  vertical spacing of output trace
nzo - int
  number of points in output trace
fmax - float
  [0.25/dt]             frequency-highcut for input traces
aperx - float
  [nxt*dxt/2]   migration lateral aperature
angmax - float
 [60]           migration angle aperature from vertical
v0 - float
  [1500](m/s)           reference velocity value at surface
dvz - float
 [0.0]                  reference velocity vertical gradient
ls -int
 [1]                    flag for line source
verb - int
  [0]   Whether or not to be verbose
max_size - int
  [100]  Approximate maximum memory to use


DESCRIPTION

Performs 2D Kirchoff depth migraion.


NOTES

1. Output regular grid is the basis of the output cmp_x and offset_x

   parameters. The input dataset should be sep3d gridded data.
   Axis 1 - time, axis 2 - trace_in_bin, axis3-cmp_x, axis4 - offset_x .
   The header keys offset_x and cmp_x must exist in the dataset.

2. This is SU's sukdmig2d code with only very slight modifications.

   All credit belongs to  CWP.  If you use it in a paper
   make sure to credit them.

3. Only works meters/feet for some reason???

4. Traveltime tables were generated by program rayt2d (or other ones)

   on relatively coarse grids, with dimension ns*nxt*nzt. In the
   migration process, traveltimes are interpolated into shot/gephone
   positions and output grids.                                  ',

5. If the offset value of an input trace is not in the offset array

   of output, the nearest one in the array is chosen.

6. Memory requirement for this program is about

        [ns*nxt*nzt+noff*nxo*nzo+4*nr*nzt+5*nxt*nzt+npa*(2*ns*nxt*nzt

+noff*nxo*nzo+4*nxt*nzt)]*4 bytes

   where nr = 1+min(nxt*dxt,0.5*offmax+aperx)/dxo.

6. Amplitudes are computed using the reference velocity profile, v(z),

   specified by the parameters v0= and dvz=.


AUTHOR

   Zhenyue Liu, 03/01/95,  Colorado School of Mines


CATEGORY

seis/image