Statistical Wavelet Extraction
Insight offers a process for statistical wavelet extraction. This process extracts wavelet from seismic data. It considers all input seismic traces within the analysis region specified by the input probe. The frequency spectra of the autocorrelation of all input traces are stacked to produce the wavelet.
As a prerequisite, you should define a probe (see Creating a Probe) to specify the block of seismic data to be used in the extraction. You can configure the wavelet length and phase as well as define the wavelet tapering (in percentage of wavelet length) in the extraction process.
How wavelet is extracted in the process:
- Calculate the autocorrelation of each trace in the analysis window. Length of the autocorrelation is based on the wavelet length you have defined.
- Calculate the frequency spectrum of each autocorrelation.
- Take the square root of the modulus of each frequency spectrum, the zero Hertz component is muted to zero. This step approximates the wavelet spectrum.
- Stack the spectra.
- Add the wavelet phase.
- Take the inverse Fast Fourier Transform (FFT) to extract the wavelet.
Available in: Explorationist module
- In the Control Panel, open the Wavelet tab.
- At the tab header, click the Add icon and click New Wavelet Extractor (Statistical).
- Type a name for the process and click OK. The new process item will be available in the Wavelet tree.
- In the Details Panel at Volume, select the seismic data to be used in the extraction process. The volume must be sampled in time. If the volume is sampled in depth, configure the Time/Depth Conversion for Insight to perform the conversion.
- Select a probe to constrain the seismic traces used in the extraction process. To add more than one prob, click the + icon in the Probes section.
- At Wavelet length (ms), define the length of the output wavelet.
- Define the phase of the wavelet at Wavelet phase (°). After stacking the spectral information extracted from each input trace, the resulting wavelet is shifted by this phase
- At Wavelet tapering %, type the percentage of wavelet length to taper the seismic traces down to zero at each end. This value determines the total proportion of the wavelet which is tapered (e.g. 50% tapering means that 25% of the total wavelet from each endpoint is tapered).
- Type the name of the wavelet at Wavelet name. If you leave this blank, the wavelet name by default will be based on the name of the process that creates it.
- When more than one probe is selected, the following options are visible in the Outputs section:
- Combined wavelet field (selected by default)
- Individual wavelet field per probe
- Click Execute to run the process. For more than one probe, the following occurs:
- If Combined wavelet field was selected, the process creates a single wavelet field containing an entry per probe.
- If Individual wavelet field per probe was selected, the process creates one wavelet field per probe.
- Once the process completes, a new wavelet item is available in the Wavelet tree.
- Save the current session and the wavelet will be saved in the project database.