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Attributes and Data
To describe the Seismic Attributes that Attrib3D computes, we have
adopted a classification system to group them by two classes, physical
or geometric. Physical attributes are computed on a trace-by-trace
basis and describe how attributes change over time whereas geometric
attributes are derived from a multi-trace-based computation scheme
and describe the spatial behavior of the attributes. Data input
to Attrib3D requires a 32-bit floating-point format, however data
may be output in Conventional 32-bit floating-point SEG-Y data,
16-bit fixed-point data, 8-bit fixed-point data, .VOL format.
For more information on Attribute, click on the active hyperlink
that will result in a pop-up window describing it's formulation.
Physical Attributes
Instantaneous Attributes
The Instantaneous Attributes are computed for each sample of the
input trace independently. The basis for the computation of most
instantaneous attributes is the model of the seismic signal as a
complex trace consisting of the real part, which is the signal recorded
by the geophone, and imaginary part, which can be computed as the
Hilbert transform of the real part.
Wavelet Attributes
The Wavelet Attributes are similar to Instantaneous attributes,
but their values are computed at the peaks of the instantaneous
Trace Envelope. Wavelet attributes, by definition, are the instantaneous
attributes computed at the maximum point of the envelope. We assume
that a seismic wavelet or a compound wavelet occupies the timespan
between two adjacent envelope minima. The program searches for positions
of the envelope minima and maxima. All envelope maxima positions
are used to obtain the instantaneous attributes and these values
are assigned to the samples over the time zone between the minima
on either side of the maximum position. We compute the position
of the maximum of the envelope and all of the attributes by quadratic
interpolation in order to be more accurate. The physical meaning
of all the wavelet attributes is essentially the same as their instantaneous
counterparts with Wavelet Apparent Polarity being the only exception.
- Wavelet Envelope
- Wavelet Envelope Time Derivative
- Wavelet Envelope Second Derivative
- Wavelet Phase
- Wavelet Frequency
- Wavelet Frequency Envelope Weighted
- Wavelet Acceleration Of Phase
- Wavelet Dominant Frequency
- Wavelet Band Width
- Wavelet Q
- Wavelet Apparent Polarity
Geometrical Attributes
For each trace, geometrical attributes are calculated by scanning
the adjacent traces and computing various characteristics defining
event dip, continuity, etc.
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