2D SEG-Y Elevation Issue

TimPoole

Using the new Geophysics module in Leapfrog Geo I've been trying to import some 2D SEG-Y files that I have downloaded from SARIG (line 86AK-7)

The profiles plot in the correct XY location however they plot well below the topographic surface.

I've played around with different import parameters but the best I can get is about 300m below the actual topographic surface. 



One thing I have noticed is that Leapfrog brings in or calculates the elevation at -(minus), the screen grab below shows the XYZ for a location on the profile. The elevation is -155m. The actual elevation is 155m which is why its plotting ~300m below the surface. 



Does anyone have any experience or can help in bringing these profiles into Leapfrog Geo at the correct elevation?

Thanks
Tim

jasonMcIntosh

Hi Tim 

Currently when you import a SEG-Y file, the default "first sample at" is correct for Time but wrong for Depth. The user should change this to the channel at byte loc 53 or 57 (source/receiver elevation datum). This should place the section at the correct location on the Z-scale. 

We will look at fixing the incorrect default for a future release.

Thanks,
Jason

TimPoole

Hi Jason

I have tried that, I've also tried using byte location '41 receiver group elevation' and '45 surface elevation at source' but it still plots about 150m below topo.

However using a 'double bluff' type method and setting the First sample at "User" then -150 this does set the top profile elevation to 150m.



This will work for what I need here as its fairly flat but its not ideal.

Thanks
Tim