Topic:
How to make a synthetic and tie it to the seismic.

Description:
This is a bare-bones description of how to make a synthetic, tie it to your
seismic, and create a shifted synthetic and a new DVT that will correctly
position your tops, logs, etc., along the borehole.
This description assumes that your well information (datums, deviation survey)
is correct, and that your sonic log is of decent quality.
* For more detailed synthetic workflow, see the entry:
  How to checkshot correct a sonic log and use that calibrated log 
  to create a synthetic

Solution:
First create a synthetic:

1.)  Open Synthetics (Session Manager > Application > Synthetics), and under
     File > Well > Well list >, select the well, then click the 'OK' button.

* For this example, we will use the default wavelet, which is a 30 Hz Ricker.
  If you want to create your own wavelet, it can be easily done under 
  Mode > Wavelet.  Details on creating a wavelet can be found in the entry:
  How to checkshot correct a sonic log and use that calibrated log to create
  a synthetic (Step 9). 

2.)   Under Mode > Synthetics >, Select your sonic log, click 'Apply', and then 
      click 'Apply' in the 'Generate synthetics/multiples' window.

3.)  Under File > Save > Synthetic data, select 'Synthetic 1' in the 'Synthetic
      tracks' dialog box, and type in a class name in the 'Name' field under
      'Synthetic classes' (and a description in the 'Description' field if
      desired).  Then, under 'DVT Operations', toggle on 'Create New DVT',
      and toggle on 'Yes' under 'Preferred DVT', and click 'Save Synthetic
      Class' (answer Yes to questions concerning deviations/DVTs).  Then dismiss
      the 'Save synthetic data' window.

  Note: This process integrates the us/ft values from the sonic log into 
        ft/sec values for the well's DVT, 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 synthetic to be positioned incorrectly.

To tie the synthetic to the seismic:

1.)  In the Seis3DV/2DV window, select Define > Well Appearance > Vertical, and 
     select an appearance file from the list.
  
2.)  Click on the 'Synthetics options' box, and in the Synthetic Selection
     menu, toggle 'Display synthetics' on, toggle 'Synthetic location' to 
    'placed'.  Select the Synthetic class you created in step 3 when creating
     a synthetic, fill in the display parameters and click 'Dismiss'.  Enter a 
     new name for the well appearance and click the 'Create' button, and then
     click the 'Dismiss' button.

3.)  In a Seis3DV/2DV window select a line near your borehole, (Session Manager 
     > Application > Interpretation > Seis3DV > Display > Seismic Line, select
     a survey and line and click the 'OK' button), and post the borehole with 
     the appearance set created in step 2 above (Post > Wells, select a well 
     set and appearance set and then click on the down arrow, and click the  
     'Ok' button).

4.)  The synthetic will now be posted at the borehole.  To tie the synthetic
      to your seismic, select Tools > Synthetic >, and after the Synthetic
      Placement box pops up, click on your synthetic with MB1, and a box will
      appear around it.  Use the up and down arrows to position your synthetic 
      so that it ties your seismic.  Note the time shift in the Synthetic 
      placement box.

Now we will create a synthetic that is shifted to tie your seismic.  We will
also use the time shift information to create a corrected DVT which will
position your curves, markers, etc. along the borehole, reflecting the time 
shift you just picked.

1.)  Open Synthetics (Session Manager > Application > Synthetics), and under
     File > Well > Well list, select the well.

2.)  Under Mode > Synthetics, click on the 'Select sonic' button, select your 
     sonic log from the list and click 'Apply'. Enter the time shift in the  
     'Bulk shift (msec)' text box, and click the 'Apply' button.

3.)  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' 
     (answer Yes to questions concerning deviations/DVTs).  Then dismiss the 
     'Save synthetic data' window.

The log displayed in the seismic window will now be shifted the amount 
specified in synthetics.



Last Modified on: 26-JAN-99