Spectral Decomposition
The Spectral Decomposition dialog allows you to generate a frequency slice file over a selected window, or a time slice for a discrete frequency.
Determine if you are generating a Frequency Slice or Discrete Frequency/Time Slice and follow the appropriate steps. Note: Generally a Frequency Slice is created first to isolate specific frequencies of interest used in the generation of a Discrete Frequency/Time Slice.
How do I generate a Frequency Slice?
- Select the volume
and define map
extents
to be used in the
generation. Note: By default,
the full extents
are in the Data Loading Extents box. You can restrict the data
extents by using
, or by typing in different
extents. - Define the window of data to be
used when generating the
slice volume. Define the Taper
to be used in the transform.
- Set the range of frequencies over
which the slice volume is
to be
generated. Specify output options
for the slice volume.
- (Optional) Set generation parameters
for the optional SEG-Y
volume.
- Click
to generate the frequency slice file.
Note:The results can be displayed in the Seismic Viewer using the Slice selection Icon (
),
and on the Basemap by selected the slice group from the Slice Group to Display list on the Slice Toolbar.
How do I generate a discrete frequency/time slice?-
Select the volume and define map extents to be used in the generation and click next. Note: By default, the full extents are displayed. You can restrict the data extents by using
, or by typing in different
extents. -
Define the zone that will be sliced. Define the taper to be used in the transform and set a slice window. Note: The slice window should be approximately the total time window used when generating the frequency slice.
-
Set the range of frequencies for which a unique slice volume will be generated. If only one volume is required, set the start and end frequencies to the same value. Specify output options for the slice volume. Note: To create a discrete frequency time slice file that can be bulk shifted independently from the SEG-Y volume used to generate the file, create a new SEG-Y file. The bulk shift of the discrete frequency time slice file and the new SEG-Y file will be zero.
-
Click
to generate the discrete frequency time slice file(s) and the SEG-Y file.
Note:The results can be displayed in the Seismic Viewer using the Slice selection Icon (),
and on the Basemap by selected the slice group from the Slice Group to Display list on the Slice Toolbar.
General Information
Select Seismic Files
Left click on the line that you want to use to create a frequency
slice, or set of discrete frequency slices. The working set
version is listed,
but alternate datasets can
be
selected by clicking on the down arrow in the Dataset
cell. To help you make your seismic file selection, you can sort any
column by
left clicking
on the column header, apply a filter (
), or type a search string
into the search
bar to limit the list using Line,
or Dataset information.
When you select a seismic file, the full extents of the file will populate the Data Loading Extents. These can be changed manually, or selected from the map.
For additional selection and navigation options right click on the Seismic Files list to access
the shortcut
menu.
Slice Type
Generate a Frequency Slice:When generating a Frequency Slice file, using the Time Window samples are transformed from the time domain into the frequency domain using a Fourier transformation. A taper can be supplied to eliminate the high frequencies that can appear at the edges of the time window. The frequency slice data is normalized by taking the median amplitude for each slice and scaling the amplitudes up or down by a scale factor relative to this median across all slices. When using the Fourier transformation, phase can also be generated. The phase is useful to delineate lateral discontinuities, such as faults, where as amplitude is used to delineate features.
Generate
Discrete Frequency/Time Slices: When generating
Discrete
Frequency/Time Slices, starting at the first time in the Time Window, the data contained in the Slice Window centered on the first time value is transformed from the time domain into the frequency domain using a
Fourier transform. Then, the
amplitude or phase at the discrete frequency is written
into a slice file at the time corresponding to the first time value in the Time Window. The Time Window is moved downward by one sample, and the process is repeated. One slice file is generated for each discrete frequency of interest.
Data Loading Extents
Start Trace: Specify the start trace for the output file. The default is the start trace of the input file.
End Trace:Specify the end trace for the output data file. The default is the end trace of the input file.
Trace Increment:Specify the trace increment for the output data file. The default is the trace increment of the input file.
Start Line: Specify the start line for the output file. The default is the start line of the input file.
End Line: Specify the end line for the output data file. The default is the end line of the input file.
Line Increment:Specify the line increment for the output data file. The default is the line increment of the input file.
Select
From Map: Define the data loading
extents by selecting from the map.
Click on the Select From Map button, then select
an area of a 3D survey from the Basemap. Click and release the
left mouse
button on the 3D survey to select the start,
and then left click again on the 3D survey to select the end.
This is very useful when trying to select an area that doesn't
encompass the entire 3D survey. If you hit the Select From
Map button by accident, click on it again to cancel the map selection.
Spectral Decomposition Options
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