Effective Eta Picking
In the Imaging tab, you can also conduct anisotropic RMO imaging (ETA picking).
Eta picking uses a semblance calculation to determine the optimum parabolic fit of observed events in the gather. You can see the calculated Semblance volumes and parabolic picks in the Gather View.
ETA picking can be done on a full volume or volume between two horizons, and/or constrained within a probe or a polygon area.
Available in: Image Gather Processing module
Settings for Effective Eta picking
- In the Control Panel, open the Imaging tab.
- Click the Episode (see Create Episode for RMO picking).
- Select the RMO to open the Details Panel.
- Inner Mute / Outer Mute: If you have picked the inner and/or outer mutes (see Manually Picking a Mute and Creating an Angle Mute), select to include muting in the RMO picking.
- Use Vertical Ramp: Click to enable vertical ramp.
- Outer Mute: The outer mute to apply to a gather before picking.
- Ramp Distance: Mute ramp distance.
- Constrain to area: Optionally constrain the region picked to the area covered by a polygon or probe.
- Semblance eta: The range and increment of eta for the semblance volume that is produced. The semblance volume will use a varying window length defined by the layers below.
- NMO Velocity volume: Velocity volume to use.
- NMO Velocity type: Type of the velocity volume.
- NMO Velocity unit: Unit of the velocity volume.
You must define at least one layer by specifying a horizon or constant value for top and base. Additional layers may be inserted using the blue “+” button, or removed using the red “x” button.
The layer parameters apply at the layer boundary and are linearly interpolated across the interval between them.
- Pick on this horizon: Place a pick on this horizon (subject to the minimum semblance setting).
- Skip location if horizon missing: If unchecked and the horizon is missing at any gather the picker may still attempt to pick other layers if there is at least one. An out-of order horizon (such as being above the previous layer horizon) will also be treated as missing. The gather may still be skipped if the intervals above and below the missing horizon cannot be combined because they have conflicting settings (such a different event type).
- Window Length (ms): Size of the vertical window used for picking.
- Range of eta: Limits the events that may be picked to those having an effective eta within this range.
- Minimum pick spacing: Prevents events being picked that are closer that this vertical distance.
- Minimum semblance: Events with a computed semblance below this value will not be picked.
Pick this interval: If checked the picker will attempt to pick events in the interval between the horizons above and below, with the other settings linearly interpolated across the interval.
- Positive Event: Pick only events that follow a peak
- Negative Event: Pick only events that follow a trough
- Positive and Negative Events: Pick both types of events
See Configure Display Settings (RMO) to set the display settings.