Velocity Picking Overview
The interactive Velocity Picking tool allows for rapid velocity picking in Insight.
In addition to configuring the display of the semblance and picks, it can also be used to conduct interpolation/extrapolation and calculate stack from your NMO-corrected gathers.
Before you can create a new velocity picking, you have to first create an Episode in the Imaging tab.
Episodes function as folders in the Imaging tree and contain the velocity picks. The prefix is used as DUG's internal naming rule, in which users are required to name their directories (hence their episodes) sequentially. This way, you will be clear in exactly what order things were done as a typical imaging workflow involves multiple iterations of picking/tomography/migration.
When you have your Episode set up, you can create new velocity picks inside the Episode. See Create a Velocity Picking for more information.
As soon as it is created, the Velocity Picking window will automatically be displayed.
The window consists of a Control Panel and three different views:
- Gather View
- Semblance View
- Eta Semblance View.
For descriptions of each view, see Using the Velocity Picking Window.
Most of the velocity picking settings can be found in the Control Panel.
- From the General tab of the Control Panel, you can select mutes to mute your gather, and/or define your water bottom horizon. If you have previously picked on the velocity, you can also import the picks to add or replace any existing picks (see Configuring the Velocity Picker).
- The Semblance tab of the Control Panel allows you to adjust the extents and increments of the time, velocity and eta that Insight will consider when generating the semblance (see Configuring the Semblance).
- Once you have your picks, interpolate or extrapolate them from the Interp tab to create a complete velocity model (see Velocity Picking Interpolation/Extrapolation).
- In the Stacking tab of the Control Panel, select the stacking mode for Insight to calculate the stack (see Stacking).
- The display settings for the Velocity Picking window can be configured from the Display tab (see Configuring Display Settings). There, you can change the line thickness, size and colour of picks.
Now that you have created and configured your velocity picking, it is finally time to start picking in the Semblance View. As you pick the velocity, the gather will be update on-the-fly in the Gather View.
There are several exceptions that make velocity picking unique in Insight. For example, if you click on a point within the minimum pick spacing of another pick, Insight will not create a new point. Instead, the nearest existing pick will move to that point.
For more information, see Picking the Velocity.
To export the completed picks, simply right click on the velocity picking in the Imaging tab and select Export Picks.
If you are working on a project that requires picking to be divided into multiple sub-projects, you may want to import picks to combine them. This will create a smoother velocity model.
For more information on how to import and export picks, see Exporting/Importing Velocity Picks.