NAME

     fluirep - module to perform Biot-Gassmann  consistent  fluid
     replacement modelling on well log data.

SYNOPSIS

     fluirep [ -Nntap ] [ -Ootap ] [ -sdp ] [ -edp ] [ -rhg  ]  [
     -rhf ] [ -rhw ] [ -rhh ] [ -kw ] [ -khy ] [ -sw ] [ -pc ]

DESCRIPTION

     fluirep performs fluid replacement  modelling  on  well  log
     data files using Biot-Gassmann relations.  The logs are sup-
     posedly  from  water  wet  wells   (i.e,   not   hydrocarbon
     affected).   The  only format of the input allowed so far is
     the LPS format used by the ILIS suite of programs, including
     the  24-line  header.  All moduli in the input are expressed
     in Mpsi, all velocities in ft/sec, densities in  gm/cc,  and
     depth  in feet.  The output is another LPS-formatted file in
     which the P-wave and S-wave velocities and bulk density have
     been  replaced  by the Biot-Gassmann modelled values and the
     second auxiliary trace contains the Vp-Vs ratio. This output
     file  is  suitable  for  further  processing  within ILIS to
     create an offset (acoustic) synthetic.  Fluid replacement is
     performed ONLY in sands, identified by LPS lithology codes 3
     and 4.  It is important to have accurate lithology codes for
     this modelling to work sensibly.

     The fluid properties, that  is  the  densities  and  moduli,
     should  be  those which are relevant for the temperature and
     pressure of the reservoir in question.  These may be derived
     from BIOTMOD within ILIS or from RocKit.

     fluirep gets its data and parameters from command line argu-
     ments described below.

  Command line arguments
     -N ntap
          Enter the input LPS file name immediately after  typing
          -N.   This  input file should include the complete path
          name if the file  resides  in  a  different  directory.
          Example  -n/b/tsp/dummy  tells  the program to look for
          file 'dummy' in directory '/b/tsp'.  (Default = stdin)

     -O otap
          Enter the output LPS file name immediately after typing
          -O.   Specify  the  full  path  to  write the file to a
          directory other than  the  current  working  directory.
          (Default = stdout )

     -sdp start depth
          Enter the starting depth, in feet, for  fluid  replace-
          ment.   All moduli for depths less than this are output
          unchanged.  Default = 1.0.

     -edp end depth
          Enter the ending depth, in feet, for fluid replacement.
          All  moduli  for  depths  grater  than  this are output
          unchanged.  Default = 1000.

     -rhg grain density
          Enter the density of the grains making up the matrix of
          the  rock  being  modelled, in gm/cc.  Enter a value of
          '0' (-rhg0.0) to cause the program  to  use  the  grain
          density  values  from  the  input file.  Otherwise, the
          entered value or the default will be used.   Default  =
          2.65.

     -rhf fluid density
          Enter the apparent fluid density, in gm/cc, as seen  by
          the  logs.   This  will often be very close to 1.0, but
          will vary in the presence of  hydrocarbons,  especially
          gas.  The  entry here is probably close to the mud den-
          sity, but in the absence of other information, use  the
          default.  Default = 1.0

     -rhw brine density
          Enter the  density  of  the  brine  in  the  formation.
          Default = 1.0

     -rhh hydrocarbon density
          Enter the density of the hydrocarbon in the  formation.
          Default = 1.0

     -kw bulk modulus of brine
          Enter the bulk modulus, in Mpsi, of the  brine  in  the
          system.

     -khy bulk modulus of hydrocarbon
          Enter the bulk modulus, in  Mpsi,  of  the  hydrocarbon
          being modelled in the system.

     -sw water saturation
          Enter the  average  water  saturation  over  the  depth
          interval  being  modelled.   If  this  parameter is not
          entered, the Sw will be assumed to exist in  the  third
          auxiliary column of the input file.

     -pc porosity cutoff
          Enter the minimum value  of  sand  porosity  for  which
          fluid  replacement will be performed.  For any porosity
          values less than this, the fluid  replacement  will  be
          skipped. Default = 3%.

AUTHOR

        Richard Margesson  London

COPYRIGHT

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