SYNOPSIS
PERL PROGRAM NAME:
AUTHOR: Juan Lorenzo (Perl module only)
DATE:
DESCRIPTION:
Version:
USE
NOTES
Examples
SYNOPSIS
SEISMIC UNIX NOTES SUKDMDCR - 2.5D datuming of receivers for prestack, common source
data using constant-background data mapping formula.
(See selfdoc for specific survey requirements.)
sukdmdcr infile= outfile= [parameters]
Required file parameters:
infile=stdin file for input seismic traces
outfile=stdout file for output
ttfile= file for input traveltime tables
Required parameters describing the 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 in table
ns= number of sources in table
ds= x-coordinate increment of sources in table
Parameters describing the input data:
nxso= number of shots
dxso= shot interval
fxso=0 x-coordinate of first shot
nxgo= number of receiver offsets per shot
dxgo= receiver offset interval
fxgo=0 first receiver offset
dt= or from header (dt) time sampling interval of input data
ft= or from header (ft) first time sample of input data
Parameters describing the domain of the problem:
dzo=0.2*dzt vertical spacing in surface determination
offmax=99999 maximum absolute offset allowed
Parameters describing the recording and datuming surfaces:
recsurf=0 recording surface (horizontal=0, topographic=1)
zrec= defines recording surface when recsurf=0
recfile= defines recording surface when recsurf=1
datsurf=0 datuming surface (horizontal=0, irregular=1)
zdat= defines datuming surface when datsurf=0
datfile= defines datuming surface when datsurf=1
Optional parameters describing the extrapolation:
aperx=nxt*dxt/2 lateral half-aperture
v0=1500(m/s) reference wavespeed
freq=50 dominant frequency in data, used to determine
the minimum distance below the datum that
the stationary phase calculation is valid.
scale=1.0 user defined scale factor for output
jpfile=stderr job print file name
mtr=100 print verbal information at every mtr traces
ntr=100000 maximum number of input traces to be datumed
Computational Notes:
1. Input traces must be SU format and organized in common shot gathers.
2. Traveltime tables were generated by program rayt2d (or equivalent)
on any grid, with dimension ns*nxt*nzt. In the extrapolation process,
traveltimes are interpolated into shot/geophone locations and
output grids.
3. If the offset value of an input trace is not in the offset array
of output, the nearest one in the array is chosen.
4. Amplitudes are computed using the constant reference wavepeed v0.
5. Input traces must specify source and receiver positions via the header
fields tr.sx and tr.gx.
6. Recording and datuming surfaces are defined as follows: If recording
surface is horizontal, set recsurf=0 (default). Then, zrec will be a
required parameter, set to the depth of surface. If the recording
surface is topographic, then set recsurf=1. Then, recfile is a required
input file. The input file recfile should be a single column ascii file
with the depth of the recording surface at every surface location (first
source to last offset), with spacing equal to dxgo.
The same holds for the datuming surface, using datsurf, zdat, and datfile.
Assumptions and limitations:
1. This code implements a 2.5D extraplolation operator that allows to
transfer data from one reference surface to another. The formula used in
this application is an adaptation of Bleistein & Jaramillo's 2.5D data
mapping formula for receiver extrapolation. This is the result of a
stationary phase analysis of the data mapping equation in the case of
a constant source location (shot gather).
Credits:
Authors: Steven D. Sheaffer (CWP), 11/97
References: Sheaffer, S., 1999, "2.5D Downward Continuation of the Seismic
Wavefield Using Kirchhoff Data Mapping." M.Sc. Thesis,
Dept. of Mathematical & Computer Sciences,
Colorado School of Mines.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 aperx
sub datfile
sub datsurf
sub ds
sub dt
sub dxgo
sub dxso
sub dxt
sub dzo
sub dzt
sub freq
sub fs
sub ft
sub fxgo
sub fxso
sub fxt
sub fzt
sub infile
sub jpfile
sub mtr
sub ns
sub ntr
sub nxgo
sub nxso
sub nxt
sub nzt
sub offmax
sub outfile
sub recfile
sub recsurf
sub scale
sub ttfile
sub v0
sub zdat
sub zrec
sub get_max_index
max index = number of input variables -1