NAME
logm2vz - convert logm format from gma into format for
xrpm/pwmvzn.
SYNOPSIS
logm2vz [ -Llogm ] [ -VCvcrds ] [ -zblockzb ] [ -lhdln ] [
-vivel ] [ -didepth ] [ -Zzmaxpad ] [ -ZVzmaxv ] [ -Wwatbot
] [ -WVwatvel ] [ -kbbushing ] [ -Ddelimiter ] [ -nncols ] [
-DVdv ] [ -f2mv ] [ -f2md ] [ -micro ] [ -V ] [ -? ] [ -h ]
DESCRIPTION
logm2vz reads depth and interval velocities from a logm-
formatted ascii file (or any ascii file which contains
columns of depths and velocities) and creates an ascii file
that can be used as input to programs pwmvzn, cmmvzn or
3dvzmig. The velocities are carefully blocked in z and out-
put in regular z spacings. The logm format is regular in
time, therefore, irregular in depth. Logm2vz can handle
regular or irregular depth spacing. The program preserves
average travel-time through a blocked layer.
logm2vz gets both its dataset names and its parameters from
command line arguments. These arguments specify the input,
output, water-bottom, and ending-depth options.
Command line arguments
-Llogm
Enter the name of the input logm-formatted ascii
immediately after typing -L. 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.
-VCvcrds
Enter the output data set name or file immediately
after typing -O. The output data set also requires the
full path name (see above).
-zblockzb
logm2vz will compute an interval velocity for every
depth specified by this blocking-factor. For example,
if you used a zblock=10.5 ft, logm2vz will produce an
interval velocity at 10.5, 21, 31.5, ... ft. This
blocking is carefully performed in order to preserve
travel times. NOTE: For best results this blocking
factor should be a multiple of the input log sample
spacing.
-lhdln
Enter the number of lines of header information at the
start of the input file. The logm format usually has
10 rows of header information. If your file contains
something other than 10, use this argument to override
the default. (Default = 10).
-vivel
Enter the field number containing the velocities. The
velocities are usually in the third field. If your
velocities are in some other field, use this argument
to override the default. (Default = 3).
-didepth
Enter the field number containing the depths. The
depths are usually in the second field. If your depths
are in some other field, use this argument to override
the default. (Default = 2). The input depths can be
irregularly spaced, but the output will be regularly
spaced.
-Zzmaxpad
Enter the ending depth (ft or meters) for the output
velocity function. If zmaxpad exceeds the bottom of
the log, velocities will be padded with the values
"zmaxv". (Default is the depth at the bottom of the
log).
-ZVzmaxv
Enter the velocity (ft/sec or m/sec) to use as the last
velocity. This velocity is only used with the zmaxpad
parameter. (Default is last velocity in the log).
-Wwatbot
Enter the depth of the water bottom. If this value is
entered, the output velocity file will contain a water
velocity layer. (Default: not used).
-WVwatvel
Enter the velocity (ft/sec or m/sec) to use for the
water layer. (Default: first velocity on logm).
-kbbushing
Enter the distance (ft or m) from the surface (zero
depth) to the kelly bushing. This value is usually
positive unless datuming has been performed. In the
marine case, this is the distance above the surface of
the water. This value will be subtracted from the
depths in the well-log. (Default is 0).
-Ddelimiter
Enter the minimum velocity (ft/sec or m/sec). Veloci-
ties less than or equal to this value will be ignored.
Note: some logs contain "velocities" such as -999.0.
If you specify -999.0, then these "velocities" will be
ignored. By default, all velocities are used.
-nncols
Enter the number of fields in the well log. (Default is
6).
-DVdv
Enter the minimum amount a velocity must change before
a velocity is written to the output file. This parame-
ter is provided to reduce the size of the output velo-
city function and thereby speed up phase shift migra-
tions (pwmvzn and cmmvzn). Without this parameter, the
program will output a velocity every zblock depth step.
logm2vz will not output at the regular zblock you
requested, but at some multiple of zblock. Velocities
which are within dv of the previously output velocity
will not be written to the output file. Warning:
Currently, the program does not perform this blocking
in the careful manner that is required to preserve
travel times.
-f2mv
Enter the command line argument '-f2mv' to convert
velocities on log from feet to meters. Note: all
input command line arguments must be in meters includ-
ing the delimiter. (Default = Do nothing).
-f2md
Enter the command line argument '-f2md' to convert
depths on log from feet to meters. Note: all input
command line arguments must be in meters i ncluding the
delimiter. (Default = Do nothing).
-micro
Enter the command line argument '-micro' to convert
from microseconds per feet or microseconds per meter to
feet or meters per second (Default = Do nothing).
-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.
LOGM FORMAT EXAMPLE
Content-Length: 1359
X-Lines: 24
Wellname 7/11-9
Time Datum 0.000000 meters
KB 25.000000 meters
Sample Rate = 2.0 Ms. Start = 0 Ms. End = 3578 Ms.
TIME INTERVAL DEPTH REFLECTION AVERAGE RMS
~~~~ VELOCITY ~~~~~ COEFFICIENTS VELOCITY VELOCITY
msec meters/sec meters ............ meters/sec meters/sec
0.0 1871.0 25.00 0.00000 1654.0 1871.0
2.0 1871.0 26.65 0.00000 1654.0 1871.0
4.0 1871.0 28.31 0.00000 1654.0 1871.0
6.0 1871.0 29.96 0.00000 1654.0 1871.0
8.0 1871.0 31.62 0.00000 1654.0 1871.0
10.0 1871.0 33.27 0.00000 1654.0 1870.0
12.0 1871.0 34.93 0.00000 1654.0 1870.0
14.0 1871.0 36.58 0.00000 1654.0 1870.0
16.0 1871.0 38.24 0.00000 1654.0 1870.0
18.0 1871.0 39.89 0.00000 1654.0 1870.0
20.0 1871.0 41.55 0.00000 1654.0 1870.0
22.0 1871.0 43.20 0.00000 1654.0 1870.0
24.0 1871.0 44.86 0.00000 1654.0 1870.0
BUGS
None known.
AUTHOR
Gary Murphy
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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