SeisWare - Velocity as a Background

Seismic RMS Velocities

RMS velocity background
To the right we have a screen capture of a SeisWare seismic display. SeisWare has the ability to display two data vols in the same space. I prefer the underlay as a variable density plot and the overlay as variable area wiggle. Here's how I made the plot at the right using the SeisWare software:

1-Display the seismic line.

2-Right click on the seismic line and select (Main Menu), (Version/Overlay), Select your velocity file as the underlay and normal migrated stack as your overlay.

3-Select (General Properties), (Trace Scale) (Scale Mode) (User Defined) 3000 to 5000, note this is the range of velocities, (Overlay Scale) (File Peak)

There is only one problem with this work flow, you can't easily interpret the seismic. Please phone Blue Castle at (403) 265-6606 and add your name to the list requesting the ability to pick data from the overlay data set! Quote Enhancement number 13540 to have your vote recorded. This should be a very minor change for the programmer! You might also want to consider voting for the ability to set different colours for both the overlay and underlay. The program is now set to use only one set of colours! Quote reference number 13582 for this one.

So how do we do it?

The easiest way is to ask your processor to provide a velocity segy file. This option will have the advantage of using the same interpolation algorithm used by the processor.

Interval velocity background
My way is a little more complicated. I find that velocity segy files are large in size. Normally all I have is a card deck containing the velocity information.

I'm going to show how to take a velocity card image file and create your own velocity segy file! This takes a few steps with the help of BP's FreeUSP software program velin.

To the right we can see the result of having velin compute the Interval Velocity with the -force option that will igmore a RMS velocity inversion.

This even looks somewhat geological!

It takes a time rms velocity card deck and interpolates these data to fill in all time samples with a velocity values!

Here are the steps:

  1. Convert the SeisX/SeisWare segy file into USP format
  2. Create USP velocity velocity file reading a time rms velocity flat file
  3. Convert the USP velocity file back to almost SeisWare format, load this file into SeisWare
If you are brave enough to see how I really do this click on this link. Be warned, you have to be more than a Nintendo button pushing geophysicist!

Pssssst - Like my seismic line?

Pulse Seismic in Calgary has given permission to show these data. The real shot points and XY's have been removed (altered) to protect the innocent.

Do you see how I am using seismic horizons to show shot location, fold, total statics and elevation. Just follow this link to see how this is done.

Site Owner: Eric Keyser
Last Updated: July 26, 2005