There are two ways to depth convert faults sticks in Kingdom. You can either generate a velocity volume using VelPAK and then use that to depth convert the surfaces in 2d3dPAK, or depth convert the fault sticks directly in VelPAK.
To depth convert the fault sticks you must use VelPAK profiles, which work with horizons and faults rather than grids. Before detailing the steps required, it is worth mentioning that it is often considered good practise to re-interpret the faults on the depth converted sections, rather than use depth converted faults. Typically fault sticks are under-sampled, and so the depth conversion can create unusually shaped sticks in the depth domain, especially if there are velocity contrasts across grids.
If you have created a velocity model with grids, this same model is used in converting the horizons and faults. Depth converting horizons and fault sticks works on a line by line basis. Load the line geometries into VelPAK using ‘File>Open TKS…’ in the existing model & select the surveys & horizons with the import option set to ‘Merge’. For 3d surveys specify an inline increment of 1 to be sure to capture all the interpretation data (unless interpretation has been done on say every 10th inline, in which case specify the start inline with interpretation then 10 for the increment). Then specify the horizons that match the grids used in exactly the same order & finish the wizard.
Open the profile module and the horizons and any fault sticks picked on that line should be displayed. Before depth converting, it is necessary to ‘snap’ the profile i.e. create a sealed section. Use the ‘Snap’ icon to do this. Snapping can be easy or a time consuming process depending upon how ‘clean’ the interpretation is. Use the ‘Snap’ fly-out and set the options under the ‘Expert’ section to ‘Yes’ to let the software automatically fix problems for quicker snapping, but be sure to review the final snapped sections.
Once the profile is snapped, check if any faults penetrate the deepest horizon. If they do, it is necessary to specify a ‘basement’ velocity so the end of the fault stick can be depth converted. Set the current layer to 32 (“Basement”) and use the ‘Depth’ fly out to specify the depth conversion method. The easiest option is to use ‘Simple Interval Velocity’ and specify a constant as the velocity (although I know some of our customers prefer to use a more complex method such as ‘Hyperbolic Tangent’, which retains a velocity gradient but keeps velocities within a sensible bound).
Then press the ‘Apply’ button on the ‘Depth’ fly-out to depth convert the horizons and fault sticks. Do this line by line for a couple of lines before changing the ‘Snap’ fly-out to work on all unsnapped lines, snap them, then set the ‘Depth’ fly-out to depth convert all unconverted lines automatically. You can use the ‘Display’ fly-out to flip the display from time to depth & fill with interval or average velocities (if you see a blank profile screen, check the domain!)
To move the depth converted fault sticks into 2d3dPAK, you need to export them using ‘File > Export >> Profile Fault > Depth’. On the ‘Filter’ tab, specify the ‘velpak_to_geoquest_m7_2d_3d_faults.awk’ filter. The exported faults can then be imported into 2d3dPAK as GeoQuest CardImage 7 format. Be careful with the import merge options – I’d suggest renaming the fault sets for safety.