NAME

     p2iv - Picks to Interval Velocity Conversion

SYNOPSIS

     p2iv [-Npicks] [-N2vmod]  [-Ooutput]  [-Ccardfile]  [-atype]
     [-V]

DESCRIPTION

     p2iv generates a V(x,z) velocity field from a set  of  input
     picks (apkr picks) that indicate the appropriate position on
     the input model data set (created in vmod).

     The program converts the input model data set  (V(z)  suite)
     to a V(t) suite and then to a Vrms(t) or Vavg(t) suite.  The
     input pick dataset contains a V(t) function number at  every
     time  sample.  This number is used as an index to look up an
     rms or average velocity at every time sample.  Once the  rms
     or  average velocity is determined at each time sample, this
     function is typically converted to V(z) using the Dix method
     and  output.  Other output options are available.  Normally,
     p2iv is run through an apkr.flow script.

  Command line arguments
     -N picks
          Enter the name of the input pick dataset  after  typing
          -N.  These picks were with program apkr.

     -N2 vmod
          Enter the  name  of  the  input  velocity  model  suite
          dataset  after  typing -N2.  These data were created in
          program vmod.

     -O otap
          Enter the name of the output V(x,z) dataset after  typ-
          ing  -O.   This  will  be a USP-formatted dataset where
          sample values are as indicated by the output type flag.

     -aoutput type
          This flag determines the type of output:
              0 - interval velocity vs depth (default)
              1 - interval velocity vs time
              2 - Lp norm velocity vs depth
              3 - Lp norm velocity vs time

     -V   Enter -V for a verbose printout.

     -Ccardfile
          If the parameters are in a separate card file enter the
          name of that file after typing -C, or by using the cat-
          pat command a script file will be  created  which  will
          contain the command line arguments and the other neces-
          sary parameters for executing vmod.   The  script  file
          may  then  be  edited  to enter the correct values. The
          script file may be executed using the  "startjob"  com-
          mand.

          Script file format:
          p2iv -Npicks -N2vmod -Ootap \
          -p2iv.crd"\
          DEPTH       EXPONENT MAX DEPTH   DELTA Z   DELTA X
                           exp      zmax        dz        dx
          PREFILT    TR SMOOTH  Z SMOOTH
                          trsm       zsm
          POSTFILT   TR SMOOTH  Z SMOOTH    CLIP %
                          trsm       zsm      clip
          "
          #...|....1....|....2....|....3....|....4....|....5

     EXPONENT exp
          This value determines the type of  inversion  used.   A
          value  between  1  and 2 is reasonable but, most likely
          you will use 1=average velocity and 2=rms velocity.

     MAX DEPTH zmax
          Maximum depth (ft or meters)  of  the  output  velocity
          model dataset.

Depth sample interval (ms) of the output velocity model dataset.


Trace interval  (ft  or  meters)  to  be  placed  in  the  header
(optional).


     PREFILT TR SMOOTH trsm
          Number of times  to  apply  trace  to  trace  smoothing
          before  inversion.  This parameter can be determined in
          program xcube by iterative guessing.

     PREFILT Z SMOOTH zsm
          Number of times to apply sample smoothing before inver-
          sion.   This  parameter  can  be  determined in program
          xcube by iterative guessing.

     POSTFILT TR SMOOTH trsm
          Number of times to apply trace to trace smoothing after
          inversion.  This parameter can be determined in program
          xcube by iterative guessing.

     POSTFILT Z SMOOTH zsm
          Number of times to apply sample smoothing after  inver-
          sion.   This  parameter  can  be  determined in program
          xcube by iterative guessing.

     CLIP % clip
          Clip percent defines a  minimum  and  maximum  velocity
          fairway  that  the  velocity  model will be clipped to.
          This is done after the inversion  to  interval  veloci-
          ties.  The minimum velocity at each sample in the velo-
          city perturbation model multiplied by the CLIP %   will
          determine  an output minimum velocity.  A maximum velo-
          city is determined similarly.  (i.e. CLIP % = 100  will
          clip  at  the minimum and maximum velocities determined
          by the velocity perturbation  model.)   (Default=0,  no
          clipping)

  Notes on filtering
     Filtering is applied using a simple  time-variant  smoother.
     At  sample  zero (time=0, or depth=0), there is no smoothing
     done. The amount of smoothing varies  linearly  from  sample
     zero  to  the value defined at the last sample on the trace.
     The smoothing parameter defines the number of  passes  of  a
     3-point smoother at the last sample.

     Pre-filtering
          Pre-filtering is performed on rms or  average  velocity
          before  the  inversion from picks to interval velocity.
          This smoothing will help stabilize  the  inversion  and
          may prevent wild velocity variations on the output.

     Post-filtering
          Post-filtering is performed on  the  interval  velocity
          model after inversion in the same manner as the PREFILT
          smoothing. This smoothing is mostly cosmetic.

SEE ALSO

     cubevz, vmod, cubevz.flow, apkr.flow, apkr, fsi

BUGS

     None known.

AUTHOR

     Curtis Kruse

COPYRIGHT

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