NAME

     splitss - Split Spread Synthesis

SYNOPSIS

     splitss   [-Ninput]   [-Ooutput]   [-cdpcdp]   [-vtvelocity]
     [-dxtdx] [-ignoreignore] [-ncsncs] or [-xmaxdist] [-xtolfab]
     [-xsgnxsgn] [-V] [-?]  [-h]

DESCRIPTION

     splitss is a program to  synthesize  regularly-spaced  split
     spread  data. Inputs are a cdp-sorted seismic dataset (which
     can be single-ended or split-spread data) and an  RMS  velo-
     city  field. The output will be a synthesis of a "perfectly-
     acquired" split spread line, i.e., in shot-record space this
     synthesized  data  would  have  offsets  of -n*gi,-(n-1)*gi,
     ...,-2*gi,-1*gi,0,gi,2*gi,...(n-1)*gi,n*gi, (where  gi=group
     interval).   This  synthesis  is  achieved by first invoking
     reciprocity and then interpolating.   By  invoking  recipro-
     city, the program synthesizes dead traces and traces missing
     due to skipped shots or single-ended acquisition  by  repli-
     cating  a  reciprocal  trace  (the  trace  where sources and
     receiver locations are interchanged).  Additionally, missing
     or dead traces are synthesized by interpolation.  The inter-
     polated trace is created by applying a residual  moveout  to
     the  closest trace (or reciprocal trace) within a given spa-
     tial tolerance. Residual moveout values are calculated  from
     the  RMS  velocity  field.  splitss will correctly index the
     headers.

  Command line arguments
     -Ninput
          Enter the input dataset name after typing -N. This data
          must be a cdp-sorted seismic USP-formatted dataset.

     -Ooutput
          Enter the output dataset name after  typing  -O.   This
          will  be  a  regularly-spaced  cdp-sorted USP-formatted
          dataset.

     -cdpcdp
          Enter the CDP interval  (ft  or  meters)  after  typing
          -cdp.  There is no default value.

     -vtvelocity
          Enter the input velocity dataset name after typing -vt.
          This  is  a  USP-formatted  dataset  with sample values
          encoded as RMS velocities and is usually created  using
          either program velin or vlmx.  The output trace is pro-
          duced by applying a residual nmo to the  closest  input
          trace  (or  reciprocal  trace).  If no velocity tape is
          specified, then no  normal  moveout  will  be  applied.
          This  is  useful  if  the  input  has  already  had nmo
          applied.  If this is the case, you will need  to  apply
          reverse nmo after splitss.

     -dxtdx
          Enter the velocity dataset  trace  spacing  (in  ft  or
          meters)  after  typing  -dxt.   The  default is the cdp
          interval.

     -ignoreignore
          Enter a value of 1 if the GI's and SP's are zero on the
          input.  If the GI's and SP's are reasonable, leave this
          parameter off, or set the parameter to 0.  The  default
          is 0.

     -ncsncs
          Indicate how often you  wish  to  synthesize  the  shot
          records  by entering the number of cdp's per shot after
          typing -ncs.  This number must be a  positive  integer.
          Default is 2.
          Examples:
            ncs=1  synthesize a shot at every cdp location
            ncs=2  synthesize a shot at every other cdp location
                   (this is the normal acquisition configuration,
                   where a shot is taken at every receiver
                   location)

     -xmaxdist
          Enter the maximum offset after typing -xmax.  This is a
          positive   number  representing  the  absolute  maximum
          offset in feet or meters which the user desires for the
          output.  No default.

     -xtolfab
          Enter the fabrication tolerance (ft  or  meters)  after
          typing  -xtol. The fabrication tolerance limits how far
          from the nearest live trace the program is  allowed  to
          synthesize  data.  A suggested value is mindist + group
          interval (where mindist = distance from the  source  to
          the closest trace).  The default is 8*CDP interval.

     -xsgnxsgn
          Enter the signed trace distance multiplier after typing
          -xsgn.  The assumed signed trace convention for splitss
          is:

             the negative offset corresponds to data where the
             source precedes the receiver along the line;

             the positive offset corresponds to data where the
             receiver precedes the source along the line.

          If the input data is the  reverse  of  this  convention
          (which  often  is the case with marine data), the value
          for xsgn should be entered as -1. The default is 1.

     -V   Enter -V on the command line for verbose printout.

     -?   Enter this (or '-?' if you are running in  c-shell)  to
          get  online  help.   The  program  will terminate after
          printing this.

     -h   Enter this option to get online help.  The program will
          terminate after printing this.

COMMENTS

     The near trace is used to synthesize all of  the  traces  in
     the gap, so caution must be taken that this trace is free of
     artifacts.

     The following line header words are altered by splitss:
           NumSmp     NumTrc     NumRec
           SmpInt     Format

     The following trace header words are altered by splitss:
           RecNum     TrcNum     SrcPnt
           SrcLoc     PrRcNm     PrTrNm
           DstUsg     RecInd     DstSgn
           DphInd     StaCor     DatShf
           SoPtNm

BUGS

     No known bugs.

AUTHOR

     N. D. Whitmore, Jr.

COPYRIGHT

     copyright 2001, Amoco Production Company
               All Rights Reserved
          an affiliate of BP America Inc.