Topic:
How to create a DVT from a sonic that will correctly position my curves and markers.

Description:
Here is the procedure for creating DVT's that will put your sonic in the
correct position on your seismic.  This assumes you have a good marker on 
your sonic, and you know where it belongs on your seismic.

Solution:
Begin by creating a DVT from your sonic.

  1.)  In DataManager > Wells > Wells, select your well, and click on 
       'Log Header.

  2.)  Select your sonic log from the Select Log Name dialog box, and then
       click create DVT from sonic.  Note the name of the DVT created.
       (it should be )

* Note: This process integrates the us/ft values into ft/sec values, and
  creates a Time/Depth/Velocity relationship for the log.  In this process,
  the velocity for the first sample in the log is used for a constant velocity
  from the top of the sonic log to the Seismic datum.  This assumption will
  invariably cause the log to be positioned incorrectly.

  3.)  In DataManager > Wells > Well + T/D, select the well, and associate it
       with the newly created DVT.

  4.)  Display the well with the sonic log, and make note of the time position
       of your marker on the sonic log.

Now we determine the shift required to correctly position the log on the
seismic, and apply the shift.

  5.)  Calculate the shift required for the sonic log marker to line up with the
       seismic event (shifting the marker down requires a positive shift,
       shifting it up requires a negative shift).

  6.)  Open Synthetics, and under File > Well > Well list, select the well.

  7.)  Under Mode > Synthetics, select your sonic log, enter the shift under
       Bulk shift (msec), and click 'Apply'.

  8.)  Under File > Save > Synthetic data > select Synthetic 1 in the Synthetic
       tracks dialog box, and type in a class name in the Name field for
       Synthetic classes.  Then, under DVT Operations, toggle on Create New DVT,
       and toggle on Yes under Preferred DVT, check to make sure the bulk shift
       is what you specified, and click 'Save Synthetic Class'.

The log displayed in the seismic window will now be shifted the amount 
specified in Synthetics.  If you want to refine the shift, follow steps 6
through 8 again, using the new value (if you change your shift from 83 to 88
msec, you must specify 88 msec the second time around, and not just the 5 msec
difference between 83 and 88).



Last Modified on: 04-DEC-98