NAME

     tvdnmo  - module to apply/remove nmo correction  with  time-
     velocity/dip (CEPDemult)

SYNOPSIS

     tvdnmo [ -Nntap ] [ -Ootap ] [ -vvtap ] [ -rsirs ] [  -reire
     ] [ -svvrs ] [ -evvre ] [ -nsns ] [ -nene ] [ -ddscle ] [ -S
     ] [ -R ] [ -T ] [ -E ] [ -B ] [ -V ] [ -XYrace ] [ -? ]

DESCRIPTION

     tvdnmo takes a set of input traces and applies  the  dynamic
     correction given by the dip moveout equation.  Both velocity
     and dip are functions  of  time  and  are  read  in  from  a
     velocity-dip  disk  file  created by tvdin (these are in the
     form of two-trace records:   the  first  being  velocity  vs
     time;  the second being dip vs time).  Once moveout has been
     computed it is applied/removed  using  quadratic  interpola-
     tion.   The  user  may  choose to output data from before or
     after the last sample cross-over in  the  moveout  map.  The
     default  is  to  output  data from after the last cross-over
     point only.

     tvdnmo gets processing controls from the command line.  Rea-
     sonable  defaults are set up.  In addition, if no input file
     name is given, the binary trace data are expected to  be  on
     the standard input. However, a velocity model must be speci-
     fied.

  Command line arguments
     -N ntap
          Enter the full path of the  file  containing  the  data
          set.   If  not specified, input is expected to be stan-
          dard input.  If standard input  is  not  specified  and
          there  is  no  input,  e.g., program run in background,
          expect a termination. (default standard input )

     -O otap
          Enter the full path of the output file.  If not  speci-
          fied,   output  is  expected  to  be  standard  output.
          (default standard output )

     -v vtap
          Enter  the  full  path  of  the  file  containing   the
          velocity-dip  model.  This file is in SIS format and is
          RMS velocity versus two way travel time followed by dip
          (deg)  versus  two  way  time. Program will stop if the
          velocity model file  is  not  given.  The  velocity-dip
          model  must have the same sample interval and number of
          samples as the trace data.  There is  one  velocity-dip
          record,  consisting  of one velocity-time trace and one
          dip-time trace, for each  input  seismic  record.   The
          header of the vmod file must be consistent with that of
          the data file.  For this  purpose,  the  program  tvdin
          (for  interpolated  multiple/primary velocity-dip func-
          tions) is used to generate the velocity-dip file in SIS
          format.  (default none ).

     -ns ns
          First trace in record to process (default = 1 )

     -ne ne
          Last trace in  record to process (default = all )

     -rs irs
          First  record to process (default = 1 )

     -re ire
          Last  record to process (default = all )

     -sv vrs
          First  velocity record to process (default = 1 )

     -ev vre
          Last  velocity record to process (default = all )

     -d dscle
          Enter the global scale factor for the dip.  This is the
          multiplier  that  will  be  applied to all dips read in
          from the velocity-dip file. (default = 1.0)

     -E   If present data associated  with  the  portion  of  the
          moveout  map  below  the last sample cross-over will be
          output.

     -T   If present data associated  with  the  portion  of  the
          moveout  map  above  the last sample cross-over will be
          output.(note: strange things could occur when  applying
          nmo,  filtering, then removing nmo should more than one
          sample cross-over be present)

     -S   If present apply internal trace header statics  (before
          nmo).

     -R   If present remove normal moveout

     -B   If present  input  velocity  function  is  expected  in
          decreasing shot order.

     -XY trace
          If present the normal moveout sample map for the  trace
          requested  will  be  output  to a file name tvdnmo_fcn.
          This file may be accessed by xgraph for a plot  of  the
          function. (i.e. xgraph -fg black -bg white -zg black -t
          "Moveout Sample Map" -y "sample  in"  -x  "sample  out"
          tvdnmo_fcn)

     -V   Verbose mode. List command line  and  lineheader  input
          parameters.

     -?   Query  mode.   With  this  flag,  tvdnmo  will  give  a
          description  of the command line arguments and stop the
          program.

BUGS

     The routine gets the trace offset from the trace header.  It
     first  checks the DstUsg entry (unsigned trace distance) and
     if this is 0.0 it check the DstSgn entry (signed trace  dis-
     tance).   It  is  therefore  a  good idea to be sure that if
     DstUsg is non-zero, that it is correct.  If not, even if the
     DstSgn  is correct it won't be used and very strange results
     will occur.

SEE ALSO

     tvd, tvdin, tvdnmo

AUTHOR

     P. G. A. Garossino, Amoco Research, Tulsa, 1991

COPYRIGHT

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