This process creates a velocity-semblance gather by calculating the semblance for each input gather over a range of NMO velocities. The Velocity Picking window includes the same semblance velocity spectra in the default display.
See Velocity Picking for additional details on picking velocities and semblance calculations.
- In the Control Panel, open the Process tab.
- At the tab header, click the Add icon and select New Process.
- Scroll down and double-click on Semblance (velocity).
- Type a name for the process and click OK.
- Volume: Select the input gathers to analyse.
- Window Length: The length of the window for the semblance calculation.
- Offset Weighting Power: Increase the weighting of far offsets.
- Normalise: When enabled, normalise the semblance at each time to [ 0.0 to 1.0 ] (for each gather).
- TWT (ms): The maximum time and increment for the calculated semblance gather.
- Velocity: The range of NMO velocities to test
a. For gathers without NMO correction, use absolute velocities:
b. For gathers with NMO correction applied, use relative velocities:
- NMO: The NMO model and order to apply, with an optional Stretch Mute.
- Mute: Select inner and outer mutes to apply to the gathers before calculating the semblance.