NAME
SLDK - module to compute forward and inverse dip-dependent
stack along user-defined dips with optional predictive
deconvolution and/or dip filtering.
SYNOPSIS
SLDK [ -Nntap ] [ -Ootap ] [ -amam ] [ -axax ] [ -nana ] [
-ppr ] [ -olol ] [ -Pprew ] [ -sist ] [ -eiend ] [ -apapera-
ture ] [ -ovlpoverlap ] [ -dk1dk1 ] [ -dk2dk2 ] [ -tk1tk1 ]
[ -tk2tk2 ] [ -S ] [ -X ] [ -Y ] [ -R ] [ -F ] [ -H ] [ -? ]
DESCRIPTION
SLDK computes the (forward and inverse) dip-dependent stack
along user-defined dips for both unstacked and stacked data.
Predictive deconvolution may be applied to the dip spectrum.
An amplitude scaling option is provided to properly scale
the output amplitudes. Application of a rho filter compen-
sates for the high-cut filtering effects of the transforms
applied. Dip filtering may be accomplished by simply doing a
forward and inverse transform with undesirable dips outside
the range of dips in the transform or by specifying a range
of dips (and times at which they occur) to be attenuated.
SLDK gets both its data file names and its parameters from
command line arguments. These arguments specify the pro-
cessing and output options, the input and output file names,
and the start and end records.
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).
-p pr
This optional parameter is required only if deconvolu-
tion is desired. If a positive value is entered, it is
the zero dip wavelet length or the prediction distance
in ms. If a negative value is entered, it is the pred-
iction distance in zero crossings of the autocorrela-
tion function. As the dip increases the travel time of
the plane wave increases according to a cosine rela-
tion, thus the prediction should also be increased by
the same function. An entry of 0 ms will result in a
unit prediction filter being applied. Sometimes run-
ning auto, with the forward transformed data as input,
before deconvolution can be diagnostic.
-ol ol
If deconvolution is desired, enter the operator length
in ms. This entry should span the multiple period of
interest. If this parameter is not supplied, no decon-
volution is applied.
-P prew
Enter the prewhitening as a fraction. This is neces-
sary to prevent numerical instabilities in the calcula-
tion of the deconvolution operator. The effect on the
output traces of increasing prew is an overall smooth-
ing of the data. The default is .01.
-s ist
Enter start time, in ms, for the deconvolution design
window. Default is 0 ms (first sample).
-e iend
Enter end time, in ms, for the deconvolution design
window. Default is end of trace.
-am dmin
Enter the minimum dip (smallest positive or most nega-
tive), in ms/tr, along which to compute the dip-
dependent stack. Any dips in the data less than this
dip will be attenuated. No default.
-ax dmax
Enter the maximum dip (greatest positive or least nega-
tive), in ms/tr, along which to compute the dip-
dependent stack. Any dips in the data greater than
this dip will be attenuated. No default.
-na na
Enter the number of dips to be included in the dip-
dependent stack. In general, this number should be at
least as great as the number of traces being stacked,
to prevent aliasing. Better results are obtained when
using larger numbers. This parameter is required and
there is no default.
-ap aperature
Enter the width, in traces, of the processing aperature
for stacked data. The entire data set will be pro-
cessed, using groups of this size. The value to be
used here is dependent upon the dips to be stacked and,
in general, the larger the dips the larger the
aperature that should be used. Default is the number
of traces per input record. If the stacked data flag
(-X) is absent, this parameter is ignored.
-ovlp overlap
Enter the width, in traces, of the overlap between pro-
cessing aperatures for stacked data. This overlap is
necessary to minimize edge effects which can occur at
aperature boundaries when the dips change rapidly. The
default is 1/2 the aperature, but in general it may be
set to about 10% of the aperature width.
-dk1 dk1
Enter the minimum dip, in ms/tr, of the range of dips
to be attenuated in the inverse transform. This param-
eter (and the -dk2 parameter) allows SLDK to double as
a dip filtering program. Default is no "filtering",
unless the -dk2 parameter is supplied, in which case
the default is dk2.
-dk2 dk2
Enter the maximum dip, in ms/tr, of the range of dips
to be attenuated in the inverse transform. This param-
eter (and the -dk1 parameter) allows SLDK to double as
a dip filtering program. Default is no "filtering",
unless the -dk1 parameter is supplied, in which case
the default is dk1.
-tk1 tk1
Enter the time, in msec, at which the minimum attenua-
tion dip is to be applied. This parameter is ignored
if the minimum and/or maximum attenuation dips are not
specified. Otherwise, default is 0.
-tk2 tk2
Enter the time, in msec, at which the maximum attenua-
tion dip is to be applied. This parameter is ignored
if the maximum and/or minimum attenuation dips are not
specified. Otherwise, the default is the length of the
input trace.
-X Enter the command line argument '-X' to process stacked
data (or unstacked data as stacked data). If this flag
is set, the -ap parameter is required and the -ovlp
parameter is strongly recommended.
-Y Enter the command line argument '-Y' to process common
offset, common receiver, or other special sorts as
stacked data within each "record". The difference
between this option and the stacked data option above
is that the stacked data option will cause mixing
across sort boundaries, whereas this option honors
those boundaries. If this flag is set, the -ap parame-
ter is required and the -ovlp parameter is strongly
recommended.
-F Enter the command line argument '-F' to request output
of the forward dip-dependent stack only.
-S Enter the command line argument '-S' to apply amplitude
scaling of the output. Although the default is no
scaling, use of this option is recommended.
-R Enter the command line argument '-R' to TURN OFF the
application of the rho filter. This option will prob-
ably be used only when the '-F' option is used, since
application of the rho filter is strongly recommended
when computing the inverse transform. Note: The rho
filter is applied to the inverse transform when decon-
volution is applied and to the forward transform when
no deconvolution is applied.
-? -H
Enter the command line argument '-?' or '-H' to get
online help. The program terminates after the help
screen is printed.
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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