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

cpanm App::SeismicUnixGui

perl -MCPAN -e shell
install App::SeismicUnixGui