FWI artefact for some profile

[kerim371]

Hi,

Shot point spacing is 200 m.
On the picture (clipped FWI result on 5 Hz) on the top you can see vertical lines (artefacts).
Can't unrestand why this is happening... any ideas?

[mloubout]

Is this with limit_m ? If so you will get these type of artifacts if the aperture isn't large enough to have "zeros" at the edge especially for marine data so you may need larger buffer size

[kerim371]

limit_m is ON and the buffer size is 0.
But I used to do that on Viking Graben line 12 with 75 m shot spacing and there was such artefact (at least visually).
Here I have 8000m cable length... But I will test with larger buffer size and report here

[kerim371]

@mloubout you were right!
After increasing buffer size the probelm was solved.
Thank you!

[kerim371]

@mloubout I have one related question.

Do you have any ideas why such curvy lines at the top may appear?
They start to appear from 8Hz.
At 5 Hz there no such artefacts..

The streamer length is 8km and and buffer_size=1.5 km