Interpretation Workflow

First time users: I would suggest quickly scrolling through the seismic survey to get a preliminary feel for fault trends and sand structure.

1. Fault Interpretation – try different color maps; the faults may be more apparent with one color pattern than with another (black-white usually works well) AND remember the software only calculates heaves on interpreted lines and treaces, not on arbitrary lines!

• Correlating faults in Map View (Faults à Correlate) saves time because you do not have to display each seismic line on which you picked fault segments
• You can use fault triangles (Triangulation) as a measure of quality control
• USE Time Slices to verify your fault picks – with dual windows open you can modify the fault plane in Seismic View. Any change to a fault segment or fault plane will make the existing triangulation of that plane obsolete, so be sure to retriangulate after modifications.

1. Horizon Interpretation – having all fault planes toggled on in Seismic View makes the interpretation much easier. SeisWorks has four tracking modes available for digitizing horizons – choose the one most suitable for your needs

 

2. When you are finished interpreting the horizon you must create fault polygons in order to prevent ZAP! from interpolating across the fault gap. The following steps guide you through the process:

• First, use Faults à Parameters to set a maximum limit for how far from the fault the software can search for horizon picks when calculating heaves and to indicate if you want the horizons extended to the faults.
• Second, Display your interpreted horizon
• Third, Display all faults for which you want to calculate heaves
• Fourth, From the menu bar, select Faults à Calculate Heaves
• Fifth, display the fault heaves in Map View

1. Create a new mapping file, for example ‘faults’ – In map view click on (Mapping à Mapping Files à New)

 

2. After the fault heaves are calculated select Faults à Convert Heaves to Polygons. This feature allows you to modify your fault planes/polygons in Map View under Faults à Edit Polygons … be sure to toggle on Fault Polygons in the View à Contents menu box

Move cursor over the polygon you want to edit. When the cursor changes to a "star" shape, click button 1. Circular "handles" appear on the polygon at every point you originally digitized. To edit a polygon, you adjust the position of these handles. You can add new handles and move them too. To add a new handle, move cursor over selected area of polygon until a solid black circle with white outline appears, press button 1 and a new handle is positioned on the outline of the polygon. When you have finished setting the attributes for the fault, select button 3 and drag to Close Create and Editing on the Polygon Create popup menu or Close Editing on the Polygon Edit popup menu.

 

3. When the faults have been edited to your liking … In Map View select Mapping à Convert Polygons à Fault to Control Map.

 

4. Invoke Horizons à ZAP! where you will be able to specify the data, horizons, and tracking types that you want to use for the interpolation. Under the Volume Selection icon in ZAP! I would suggest creating a cube volume. For info and discussion on how to create cube data volumes, see page 291 in the Landmark manual entitled ZAP! As for the Horizon Selection, Snap/Confidence, Optional Constraints, and Tracking Parameters you will have to specify your own … depending on how you want the map to look when completed.

 

5. When you finally have a Zapped horizon the Paintbrush Option perform the functions like delete, Retrack, Fill track, Interpolate, Smooth, etc. …. ZAP! must be opened in either Map View or Seismic View!

 

6. After you have a refined structure map with horizons extending to faults, the next step will be to create a contour map. This is the part where the workflow becomes crucial, so follow the instructions very carefully! I would select your zapped/interpolated horizon and there should be a void space where the faults are located, if you have the original fault polygons toggled on, turn them off now!