NAME
rmsvel - Convert Spectral Picks to Velocities
SYNOPSIS
rmsvel [ -vmvrmsmin ] [ -dvdeltav ] [ -dxdxrec ] [ -rsirs ]
[ -R0rdel ] [ -dtdeltat ] [ -ttoltolerance ] [ -Ppicks ] [
-Mvel ] [ -Zzmax ] [ -h ]
NOTICE
rmsvel will no longer be updated after June 1993. This pro-
gram is being replaced with xsd2vlmx. See the manual page
for xsd2vlmx.
DESCRIPTION
rmsvel reads an xsd pick file and creates a file containing
RMS_velocity/time pairs and interval_velocity/depth pairs.
rmsvel computes a Dix estimate of the interval velocities
and depths. The inputs to rmsvel are the xsd picks, which
were picked on velocity spectra panels (see program vel-
spec), and command line arguments. The output from rmsvel
is a file which will be in the format expected by program
vlmx. Used together, the two programs rmsvel and vlmx may be
used to create a USP-formatted velocity field for input to
either splitss or to the post-stack and pre-stack migration
programs.
The steps below are given as an example to follow when
creating the pick file for input to rmsvel.
1) Sort data into cdp order.
2) Optionally: Run editt to select the records
you will be using to compute the velocity
spectra, using rs and R0 parameter for start
record and record increment, respectively.
3) Run velspec to compute the velocity spectra.
4) Run xsd to plot the spectra.
Use the following settings to create a velocity
field sampled every CDP interval:
Record units: 1 or R0 [from editt]
offsets: 0
Trace units: deltav in velspec, where
deltav=(vmax-vmin)/(nvel+1)
offsets: vmin-deltav [from velspec]
Sample units: dt in ms [from line header
of seismic input to velspec]
offsets: 0
Use the following settings to create a velocity
field sampled every GROUP interval:
Record units: 0.5 or R0/2 [from editt]
offsets: 0
Trace units: deltav in velspec, where
deltav=(vmax-vmin)/(nvel+1)
offsets: vmin-deltav [from velspec]
Sample units: dt in ms [from line header
of seismic input to velspec]
offsets: 0
5) Make spectral picks in xsd, and save these
in a pick file. Make sure the "honor record
numbers" button is on.
6) Use parameters from editt and velspec to
determine rmsvel parameters.
Command line arguments
-vm vrmsmin
Enter the minimum RMS velocity value after typing -vm.
This should be the parameter vmin used in program vel-
spec.
-dv deltav
Enter the increment for the velocities (in ft/sec or
m/sec) after typing -dv. This should be the deltav cal-
culated by velspec, where deltav=(vmax-vmin)/(nvel+1).
There is no default.
-dx dxrec
For the example outlined above dxrec is the cdp spac-
ing, which is normally one-half the group interval.
dxrec is the distance in feet or meters between the
locations of sequential records of the original
dataset, (i.e., the cdp sorted input dataset to editt).
Enter the dxrec value after typing -dx. There is no
default.
-rs irs
Enter the starting record after typing -rs. For accu-
racy this value should match the -rs value for starting
record given to editt. If this value is missing, it
will be set equal to the -R0 value mentioned below.
-R0 rdel
Enter the spacing (in record numbers) of the velocity
spectra panels which were used to create the xsd pick
file. For accuracy this value should match the -R0
value used in program editt.
-dt deltat
Enter the sample interval in ms after typing -dt. This
should match the sample interval of the data which was
input to editt. There is no default.
-ttol ttol
Enter the travel time tolerance interval in ms after
typing -ttol. The default is 240 ms. The
time/velocity values will be output at this time incre-
ment. If a finer sampling is desired for a smoother
velocity field from vlmx, enter a smaller value for
ttol.
-P picks
Enter the name of the file containing the xsd picks
after typing -P.
-M vel
Enter the output velocity file name after typing -M.
This is an ascii file in the format expected by program
vlmx.
-Z zmax
Enter the maximum depth in feet or meters after typing
-Z.
-h Enter -h for online help. Program will terminate after
printing this.
Example of XSD pick file
Units 10.000000 50.000000 8.000000 40 219 497 Offset
10.000000 4950.000000 -8.000000 Count 4 11
Segment = 1 Name NO_PICK_NAME_HERE color = 7 picks = 11
110.000000 5550.000000 120.000000
110.000000 5850.000000 656.000000
110.000000 6150.000000 1168.000000
110.000000 6400.000000 1536.000000
110.000000 6800.000000 1824.000000
110.000000 7350.000000 2136.000000
110.000000 8500.000000 2392.000000
110.000000 9400.000000 2760.000000
110.000000 10550.000000 3064.000000
110.000000 12000.000000 3360.000000
110.000000 15250.000000 3792.000000
Segment = 2 Name NO_PICK_NAME_HERE color = 7 picks = 7
210.000000 5800.000000 160.000000
210.000000 6200.000000 464.000000
210.000000 6350.000000 1024.000000
210.000000 6850.000000 1176.000000
210.000000 8100.000000 1648.000000
210.000000 9650.000000 2152.000000
210.000000 13550.000000 3856.000000
Segment = 3 Name NO_PICK_NAME_HERE color = 7 picks = 9
310.000000 5900.000000 312.000000
310.000000 6250.000000 672.000000
310.000000 6600.000000 968.000000
310.000000 6850.000000 1280.000000
310.000000 7350.000000 1528.000000
310.000000 7900.000000 1736.000000
310.000000 9100.000000 2296.000000
310.000000 9400.000000 2632.000000
310.000000 11000.000000 3848.000000
Segment = 4 Name NO_PICK_NAME_HERE color = 7 picks = 11
410.000000 6000.000000 248.000000
410.000000 6250.000000 608.000000
410.000000 6550.000000 864.000000
410.000000 7200.000000 1192.000000
410.000000 7400.000000 1472.000000
410.000000 8000.000000 1680.000000
410.000000 8750.000000 1968.000000
410.000000 9200.000000 2248.000000
410.000000 10250.000000 2584.000000
410.000000 11550.000000 3200.000000
410.000000 12650.000000 3792.000000
Units card:
First set of three values (10,50,8)
are (record units, trace units, sample units).
Second set of three values (40,219,497)
are (no. records, no. traces, no. samples).
Third set of three values (10,4950,-8) (after Offset)
are (record offset, trace offset, sample offset).
Last set of two values (4,11) (after Count)
are (number of segments, max. no. of picks/segment).
Segment card:
Incremental counter of pick segment number.
Name of pick. (no names applied in this case).
Color used in the picking.
Number of picks for this segment.
Pick card:
Record number (after applying unit and offset).
Trace number (after applying unit and offset).
Sample number (after applying unit and offset).
For each value on a Pick card rmsvel
will apply the offset and units in the following
manner before the value is used.
value = (value - offset) / units
A pick file created before October, 1992 may be in a
slightly different format from that shown above. If so,
rmsvel will detect this and suggest that the user run pro-
gram xsd2xsd to reformat the pick file into the new format
before running rmsvel.
vlmx, splitss, velin, rmsvlmx, mxcvel, xrpm, ivad, swath,
vfnd, vtpad, vtrsiz, vtvzex, vttd, xsd2xsd
BUGS
None known.
AUTHOR
N. D. Whitmore, Jr.
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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