How do I perform an amplitude extraction at different angles through the volumes?
This can be done by performing amplitude extractions on horizons that dip at specific angles.
Creating the initial angle horizon
- From the View menu in the Control Panel, open the Map View.
- Select an existing horizon that covers the area (the waterbottom might be a good choice).
- Expand the Operations tab and select Horizon Maths.
- Use the base formula:
IL - <minimum inline>*<inline spacing>*tan(<oblique angle>*pi/180)- This formula calculates a new horizon with depth values at a specific angle dipping in the crossline direction.
- You can replace the IL with CL to set the dip direction to the inline direction.
- Define the output as TVDSS (m) since the survey spacing is measured in meters.
- Click Run to begin the operation.
Once you have this base angle horizon, you can use the Ghost operation in Map View to move the horizon up or down by a constant amount (see Ghost). This will allow you to cut the volumes at different depths/times.
Converting time-depth
If you need to convert the horizon to time so you can extract amplitudes from time volumes, a constant velocity volume that will allow a 1:1 conversion between the TWT and TVDSS for the horizon can easily be created.
- From the Control Panel, open the Process tab.
- Click the Add icon and select New Process.
- Select Volume Maths and give the process an appropriate name.
- Set the Formula to a constant 2000. This will create a new volume under the Volume tab.
- Change the class of the volume to Average Velocity.
- From the File menu in the Control Panel, select Configure Time/Depth Conversion.
- Choose the new volume as the Velocity Volume.
Now you have dipping horizons on which you can view amplitudes/values from your volumes. Remember you can just change the horizon property to Amplitude in the Map View to do the on-the-fly amplitude extraction.