NAME

     pptrnehz - Compute a Velocity Trendline  based  on  the  EHZ
     Method

SYNOPSIS

     pptrnehz [-OBG ntap] [-VTR otap] [-nhg nhg] [-comp  cmp]  [-
     sphi phi] [-vclay clay] [-met] [-eng] [-V] [-?]  [-h]

DESCRIPTION

     pptrnehz will create  a  velocity  trendline  based  on  the
     Eberhart-Phillips,  Han, and Zoback method.  For an explana-
     tion of this method see:

          GEOPHYSICS, VOL. 54, No.1, (January 1989), P.82-89.
          "Empirical relationships among seismic velocity, effective
          pressure, proosity, and clay content in sandstone"
          D. Eberhart-Phillips, D-H. Han, and M. C. Zoback

     The program will read an overburden gradient field to deter-
     mine  the  depth,  the  depth sample rate, and the number of
     records and traces to output.  The dataset names  and  other
     parameters  are read from command line arguments.  This pro-
     gram expects the header value "Dz1000" to be present in  the
     line header.

  Command line arguments
     -OBGntap
          Enter the name of the input overburden  gradient  field
          after  typing -OBG.  This input file should include the
          complete path name if the file resides in  a  different
          directory.  Example -L/b/vsp/dummy tells the program to
          look for file 'dummy' in directory 'vsp' stored on  the
          'b' disk.

     -VTRotap
          Enter the name of the output velocity  trendline  field
          after  typing -VTR. This dataset also requires the full
          pathname (see above).  The velocity  trendline  dataset
          will be the same size as the input velocity dataset.

     -nhg nhg
          Enter the  normal  hydrostatic  gradient  after  typing
          -nhg.  The default is .465 which is correct for the USA
          Gulf Coast area.

     -comp cmp
          Enter the compaction facter after  typing  -comp.   The
          default is 5000.

     -sphi phi
          Enter the surface porosity  after  typing  -sphi.   The
          default is .4.

     -vclay clay
          Enter the volume of  clay  after  typing  -vclay.   The
          default is .4.

     -met If this flag is present on the command  line,  it  will
          indicate  that  the  depth  sample  rate from the input
          overburden gradient dataset is in meters/second.

     -eng If this flag is present on the command  line,  it  will
          indicate  that  the  depth  sample  rate from the input
          overburden gradient dataset is in feet/second.

          Note:  Units must be specified on the command line.

     -V   Enter the command line argument '-V' to get  additional
          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.

SEE ALSO

     pptrn, vel2den, ppdenobg, ppetn

BUGS

     None known.

AUTHORS

     N. D. Whitmore, Jr., Mary Ann Thornton

COPYRIGHT

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