 |
GEPH316 Seismic Data Processing
Field Data Workshop 2000 |
8 Kill noisy traces |
Noisy traces
Noisy traces usually result from noise at a particular geophone location, which may be due to a bad connection or a bad geophone at a particular receiver location that was not noticed in the field. It is best to set the whole of these traces to zero, even if there are signs of a reflection present, as the Signal/Noise ratio is bad and will damage the final stacked data.
If a particular geophone is noisy on many shots, all the traces in the line may be resorted in ascending order of geophone location. Then all the noisy traces will be grouped together and can be killed easily. Then the original order of the traces can be obtained by resorting in ascending order of shot location.
Killing noisy traces
- The sukill command can be used to kill one or more traces in a section. Try to understand the trace killing options by typing the name of the command.
sukill
- Redisplay the whole seismic line and inspect it for very noisy traces. The suximage and suxwigb plots offer different ways of looking for the noise. Select and enlarge noisy regions using the mouse to determine the trace numbers to kill.
suximage <line.cdp title='Line with noisy traces' label1='Time (s)' label2='Trace number' &
suxwigb <line.cdp title='Line with noisy traces' label1='Time (s)' label2='Trace number' &
- It appears that trace 90 is particularly noisy and should be removed. Use the sukill command to remove it. Then plot the new version of the line to check that the correct trace was removed.
sukill <line.cdp >line.kill min=90 nkill=1
suximage <line.kill title='Line without noisy trace' label1='Time (s)' label2='Trace number' &
suxwigb <line.kill title='Line without noisy trace' label1='Time (s)' label2='Trace number' &
- Check traces 155 and 156 for noise levels.
- Although these and some of the other traces show a little noise, probably they are not sufficiently bad to justify killing them totally.
- When all the correct traces have been killed, replace the original version of the line with the new version.
mv line.kill line.cdp
ls
Comments on this information may be mailed to
B.Robinson@lancaster.ac.uk
Copyright © Brian Robinson 2000. All rights reserved.
Last updated on 7/03/2000 by BR.
