SYNOPSIS
PERL PROGRAM NAME:
AUTHOR: Juan Lorenzo (Perl module only)
DATE:
DESCRIPTION:
Version:
USE
NOTES
Examples
SYNOPSIS
SEISMIC UNIX NOTES SUMIGTOPO2D - Kirchhoff Depth Migration of 2D postack/prestack data
from the (variable topography) recording surface
sumigtopo2d infile= outfile= [parameters]
Required parameters:
infile=stdin file for input seismic traces
outfile=stdout file for common offset migration output
ttfile file for input traveltime tables
The following 9 parameters describe traveltime tables:
fzt first depth sample in traveltime table
nzt number of depth samples in traveltime table
dzt depth interval in traveltime table
fxt first lateral sample in traveltime table
nxt number of lateral samples in traveltime table
dxt lateral interval in traveltime table
fs x-coordinate of first source
ns number of sources
ds x-coordinate increment of sources
fxi x-coordinate of the first input trace
dxi horizontal spacing of input data
nxi number of input trace locations in surface
Optional Parameters:
dt= or from header (dt) time sampling interval of input data
ft= or from header (ft) first time sample of input data
dxm= or from header (d2) sampling interval of midpoints
surf="0,0;99999,0" Recording surface "x1,z1;x2,z2;x3,z3;...
fzo=fzt z-coordinate of first point in output trace
dzo=0.2*dzt vertical spacing of output trace
nzo=5*(nzt-1)+1 number of points in output trace ",
fxo=fxt x-coordinate of first output trace
dxo=0.5*dxt horizontal spacing of output trace
nxo=2*(nxt-1)+1 number of output traces ",
off0=0 first offest in output
doff=99999 offset increment in output
noff=1 number of offsets in output ",
fmax=0.25/dt frequency-highcut for input traces
offmax=99999 maximum absolute offset allowed in migration
aperx=nxt*dxt/2 migration lateral aperature
angmax=60 migration angle aperature from vertical
v0=1500(m/s) reference velocity value at surface ",
dvz=0.0 reference velocity vertical gradient
ls=1 flag for line source
jpfile=stderr job print file name
mtr=100 print verbal information at every mtr traces
ntr=100000 maximum number of input traces to be migrated
Notes:
1. Traveltime tables were generated by program rayt2dtopo (or any
other one that considers topography )on relatively coarse grids,
with dimension ns*nxt*nzt. In the migration process, traveltimes
are interpolated into shot/gephone positions and output grids.
2. Input seismic traces must be SU format and can be any type of
gathers (common shot, common offset, common CDP, and so on). ",
3. Migrated traces are output in CDP gathers if velocity analysis
is required, with dimension nxo*noff*nzo. ",
4. If the offset value of an input trace is not in the offset array
of output, the nearest one in the array is chosen.
5. Amplitudes are computed using the reference velocity profile, v(z),
specified by the parameters v0= and dvz=.
6. Input traces must specify source and receiver positions via the header
fields tr.sx and tr.gx. Offset is computed automatically.
Author: Zhenyue Liu, 03/01/95, Colorado School of Mines
Trino Salinas, 07/01/96, Colorado School of Mines,
extended the code to migrate data from a nonflat
recording surface.
References :
Bleistein, N., Cohen, J., and Hagin, F., 1987, Two and one-half
dimensional Born inversion with arbitrary reference: Geophysics,
52, 26-36.
Liu,Z., 1993, A Kirchhoff approach to seismic modeling and
pre-stack depth migration: CWP Annual Report, CWP, Colorado
School of Mines.
Wiggins, J. W., 1984, Kirchhoff integral extrapolation and
migration of nonplanar data: Geophysics, 49, 1239-
1248.User's notes (Juan Lorenzo) untested
CHANGES and their DATES
Import packages
instantiation of packages
Encapsulated hash of private variables
sub Step
collects switches and assembles bash instructions by adding the program name
sub note
collects switches and assembles bash instructions by adding the program name
sub clear
sub angmax
sub aperx
sub doff
sub dt
sub dvz
sub dxm
sub dxo
sub dzo
sub fmax
sub ft
sub fxo
sub fzo
sub infile
sub jpfile
sub ls
sub mtr
sub noff
sub ntr
sub nxo
sub nzo
sub off0
sub offmax
sub outfile
sub surf
sub v0
sub get_max_index
max index = number of input variables -1