NAME
avepred - do spatially averaged predictive deconvolution
SYNOPSIS
avepred [ -Nntap ] [ -Ootap ] [ -Fftap ] [ -ppr ] [ -olol ]
[ -Pprew ] [ -xldisl ] [ -xudisu ] [ -vsvel1 ] [ -vevel2 ] [
-sist ] [ -eiend ] [ -nsnstr ] [ -nenetr ] [ -rsnrst ] [
-renred ] [ -TV ] [ -wlslide ] [ -S ] [ -C ] [ -B ] [ -G ] [
-A ] [ -D ] [ -W ] [ -H ] [ -hwhdrwrd ] [ -V ] [ -? ]
DESCRIPTION
avepred does predictive deconvolution of selected seismic
traces just like pred except the operator will be spatially
averaged over some trace interval. It will generate either
the standard prediction error output or optionally the
predictable part of the signal. The prediction filter is
designed within a user specified window defined by a start
time and a velocity.
The decon operator can be applied the each entire trace or
within the design window. If the latter, the decon'd data
should meld fairly well with the unprocessed data for most
prediction distances. Seams in the data may appear if a
spiking decon is specified.
avepred gets both its data and its parameters from command
line arguments. These arguments specify the input, output,
the design window, the start and end traces, 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).
-F ftap
Enter the optional output prediction error filter data
set name or file immediately after typing -F. No pip-
ing of this output allowed.
-p pr
This is the wavelet length or the prediction distance
in ms. An entry of 0 ms will result in a unit predic-
tion filter being applied. Otherwise care should be
taken to make this entry correspond approximately to
the nth zero crossing of the trace. Sometimes running
auto before can be diagnostic.
-ol ol
Enter the operator length in ms. This entry should
span the multiple period of interest.
-P prew
Enter the prewhitening as a fraction. This is neces-
sary to prevent numerical instabilities in the calcula-
tions. The effect on the output traces of increasing
prew is an overall smoothing of the data. The default
is .01.
-xl disl
Enter the range below which no operator design will
take place. Default is smallest range in spread. The
absolute value of the trace distance is read from the
input trace so a positive value here is all that is
required.
-xu disu
Enter the range above which no operator design will
take place. Default is largest range in spread. The
absolute value of the trace distance is read from the
input trace so a positive value here is all that is
required.
-s ist
Enter the start time of the design window. The default
is the beginning of the trace. The design window start
time can be:
(1) a constant value (read off the command line),
(2) be driven by a constant value + times derived from
trace distances and a user
supplied velocity (see -v1 command entry below),
(3) be driven by a constant value + time extracted from
a header word in each tra ce (use recshift or flatten
to insert xsd pick times), or
(4) be driven by a constant value + times derived from
the water depth trace head er entry and the user
defined velocity below. Only one of the above 4
choices ca n be made.
Any combination of the above options will also work,
the only restriction is that only one velocity can be
used. The start time units must be consistent with the
input sample interval.
-vs vel1
Enter the start design window velocity in m or ft/s.
Default is infinite velocity or constant start time for
each trace.
-ve vel2
Enter the end design window velocity in m or ft/s.
Default is infinite velocity or constant end time for
each trace.
-e iend
Enter the end time of the design window. The default
is the end of the trace. The end time can be:
(1) a constant value (read off the command line), or
(2) be driven by a constant value + times derived from
trace distances and a user supplied velocity (see -v2
command entry)
-ns nstr
Enter the process start sequential trace number. Trace
numbers below this value will not be processed but will
be passed. The default is 1.
-ne netr
Enter the process end sequential trace number. Trace
numbers above this value will not be processed but will
be passed. The default is the last trace number on the
input data set.
-rs nrst
Enter process start sequential record number. Record
numbers below this value will not be processed but will
be passed. Default value is the first record.
-re nred
Enter process end sequential record number. Record
numbers above this value will not be processed but will
be passed. Default value is last record.
-W Enter the command line argument '-W' to key the start
time to the trace header en try for water depth above
cdpth point. The actual window start time will be the
sum of this time and the command line constant start
time If this option is turn ed on and the user does
not supply a velocity (-vs[]) the line header entry is
examined f or a valid velocity (program quits if this
is not found).
-H Enter the command line argument '-H' to key the start
time on the time found in t he header word specified
below.
-hw hdrwrd
Enter trace header word mnemonic containing design win-
dow start time. The actual
-TV Enter the command line argument '-TV' to apply time
varying predictive decon (see required parameter
below). With this option all design window parameters
above st ill apply although the decon is applied only
within the design window. The -G, -S options below and
the optional operator output above are ignored.
-w lslide
Enter length (ms) of the sliding window. Effectively a
decon is done for each win dow postion on the trace;
the window is moved down by 1/2 its length and the
decon
is computed again. The individual results are merged
together by linear interpol ation. To see large
effects the sliding window length should be longer than
the operator length.
start time will be the sum of this time and the com-
mand line constant start time.
-S Enter the command line argument '-S' to output the
predictable part of the signal, otherwise the standard
unpredictable part or prediction error will be output.
-C Enter the command line argument '-C' to apply cosine
bell taper to the autocorrelation
-B Enter the command line argument '-B' to apply bartlett
(linear) taper to the autoc orrelation
-G Enter the command line argument '-G' to apply the
operator only to the data within the design window
(data outside will be untouched).
-A Enter the command line argument '-A' to use the abso-
lute autocorrelations, otherwise each auto-corr will be
normalized
-D Enter the command line argument '-D' to apply the decon
filter within the minimum and maximum absolute trace
distances used to design the filter.
-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.
AUTHOR
Paul Gutowski, TRCVM(ZPRG03), zprg03@trc.amoco.com
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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