NAME

     VNMO  - module to perform forward or inverse Normal  Moveout
     Correction Using Shifted Hyperbolas

SYNOPSIS

     VNMO [ -Nntap ] [ -Ootap ] [ -vvtap ] [ -rsrs ] [ -rere ]  [
     -R ] [ -? ] [ -h ]

DESCRIPTION

     VNMO computes and applies either forward or  inverse  Normal
     Moveout correction  to seismic data using the shifted hyper-
     bola  [S(x)]  procedure  described  by  Castle  (Geophysics,
     1994).  The corrections are computed from velocity functions
     supplied via a velocity data set in USP  format  (must  have
     one  velocity  trace  for each input cdp) and are applied in
     either direction  using  quadratic  interpolation.   Moveout
     computed  according to the Castle moveout equation including
     the space-variant S-term (S(x)) is effective for  correcting
     non-hyperbolic moveout.  Note that Castle's equations 40 and
     41 are in error.  This program uses the  corrected  versions
     (Steve Markley, Amoco, personal communication).

     VNMO gets its data from command line arguments and its velo-
     city  functions   from  a  TDFN card image file or secondary
     input data set.

  Command line arguments
     -N ntap
          Enter the input data set name or file immediately after
          typing -N.  This input file should include the complete
          path name if the file resides in a different directory.
          Example  -N/b/vsp/dummy  tells  the program to look for
          file 'dummy' in sub-directory 'vsp' of directory 'b'.

     -O otap
          Enter the output data  set  name  or  file  immediately
          after typing -O.  The output data set also requires the
          full path name (see above).

     -v vtap
          Enter the name of the  velocity  data  set  immediately
          after  typing  -v.   This input file should include the
          complete path name if the file resides in  a  different
          directory.  Example -n/b/vsp/dummy tells the program to
          look for file 'dummy' in sub-directory 'vsp' of  direc-
          tory 'b'.

     -rs Start Record
          Enter the (sequential) number of the  first  record  to
          process.   The  default  is the first on the input data
          set.

     -re End Record
          Enter the (sequential) number of  the  last  record  to
          process.   The  default  is  the last on the input data
          set.

     -R   Enter the command line argument '-R' to request inverse
          Normal  Moveout correction.  The default is for forward
          correction.

     -?   Enter the command line  argument  '-?'  to  get  online
          help.   The program terminates after the help screen is
          printed.

     -H   Enter the command line argument -h to get online  help.
          The   program  terminates  after  the  help  screen  is
          printed.

AUTHOR

        Richard Crider STAT  Houston

COPYRIGHT

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