NAME
arnmo - automatic rnmo (residual normal moceout) correction
SYNOPSIS
arnmo [ -Nntap ] [ -Ootap ] [ -Rrtap ] [ -nsnstr ] [ -nenetr
] [ -rsnrst ] [ -renred ] [ -hwhdrwrd ] [ -sist ] [ -eied ]
[ -wiwin ] [ -llags ] [ -mistk ] [ -smt ] [ -ordtordt ] [
-smx ] [ -ordxordx ] [ -T ] [ -I ] [ -V ] [ -? ]
DESCRIPTION
arnmo reads each gather (probably but not exclusively CDPs)
and uses a sliding window correlation method to determine
the time - trace residual corrections to be applied to the
events. A model trace is built using either the first live
(near) offset trace or a summation of the first n near
traces. A time weighted sliding window is then run down the
gather. At each time position the data across the gather is
extracted and the correlations of the traces with the model
trace are analysed. The correlation peaks then determine
the residual time differences between the model trace window
and the target trace window. The process is repeated for
each window position and the residual times are stored in a
matrix. Optional smoothing of the matrix is allowed and then
the the residual times are applied using a quadratice inter-
polator. Optionally, the time matrix itself may be output
so that external smoothing or other processes may be run on
the residual times. At a later stage the times may be read
back into the program for application. Results will be
dependent on the signal to noise of the data so care should
be taken to attenuate as much of the coherent noise as pos-
sible since this will confuse the correlation process. As an
example it seems to work better on angle stacks, even narrow
band stacks, than on raw cdp gathers because of the noise
attenuation that partial stacking affords.
arnmo gets both its data and its parameters from command
line arguments. These arguments specify the input, output,
the start and end traces, the start and end records, the
window length and lags, and verbose printout, if desired.
Command line arguments
-N ntap
Enter the input data set name or file immediately after
typing -N unless the input is from a pipe in which case
the -N entry must be omitted. This input file should
include the complete path name if the file resides in a
different directory. Example -N/b/vsp/dummy tells the
program to look for file 'dummy' in directory '/b/vsp'.
-O otap
Enter the output data set name or file immediately
after typing -O. This output file is not required when
piping the output to another process. The output data
set also requires the full path name (see above).
-R rtap
Enter the optional input time matrix data set. This
assumes a prior run of arnmo has generated a time data
set that has exactly the same number of records, traces
per record, and samples per trace as the input data
set. In XIKP this is port "3"
-w iwin
Enter the length of the sliding window in ms. No
default. This will govern the basic resolution of the
residual time estimation. It should be at least a cou-
ple of zero crossings to be stable and of course must
span the maximum residual time expected in the data.
-l lags
Enter the one-sided cross-correlation lags in samples.
This is the half length of the cross-correlation. If
this does not span the maximum residual time expected
in the data then this time will be missed in the
analysis. Default is 1/4 window length.
-m istk
Enter the number of nearest offset traces to stack to
build the model trace. Default = 1. Sometimes the
nearest offset traces can be weak and noisy so this is
an attempt to garner a little extra signal to noise.
-s ist
Enter the processing start time (ms). Default is the
start of the trace. Trace samples less than this will
be untouched.
-e ied
Enter the processing end time (ms). Default is the end
of the trace. Trace samples greater than this will be
untouched.
-hw hdrwrd
Enter the trace header word to extract a start time.
This values will be added to any -s[] command line
start time.
-ns nstr
Enter the start trace number. The default is the first
trace of the record.
-ne netr
Enter the end trace number. The default is the last
trace of the record.
-rs nrst
Enter start record number. Default value is the first
record.
-re nred
Enter end record number. Default value is last record.
-smt Enter the command line argument '-smt' to turn on
internal smoothing of the time matrix in the temporal
direction.
-ordt ordt
Enter the temporal smoothing order. Smoothing is done
in the isotime direction using an FFT smoother. The
default smoother is an order of 1/3 the total number of
live traces in the gather. The FFT smoother is used
because of its kind response at the edges.
-smx Enter the command line argument '-smx' to turn on
internal smoothing of the time matrix in the spatial
direction.
-ordx ordx
Enter the spatial smoothing order. The default smooth-
ing in the spatial direction is done using an order of
1/2 the sliding window length. The FFT smoother is used
because of its kind response at the edges.
-T Enter the command line argument '-T' to output the time
matrix only. The time matrix will be in units of sam-
ple.
-I Enter the command line argument '-I' to input both the
data and the times from a prior arnmo run.
-V Enter the command line argument '-V' to get additional
printout.
-? Enter the command line argument '-?' to get online
help. The program terminates after the help screen is
printed.
BUGS
Who knows; who cares
SEE ALSO
rnmo
AUTHOR
Nobody in his right mind would admit to coding this
EXAMPLES
arnmo -Nrec99 -Ojunk -w64 -l3 -m3
Assuming this is 4ms data then the sliding window is 64ms
with a maximum one-sided correlation lag of 3 samples
(12ms). The model trace is the stack of the near 3 live
traces.
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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