There is a section in the Velit Tutorial PDF on data preparation, found under the Velit Help > Explore menu, that goes into detail, but here is a summary.
1. Grid Creation
- Grids should be created from the key horizon interpretations on your 2d & 3d surveys. Only use horizons where it looks like you have significant velocity changes (based on your well logs and/or seismic velocities). Typically, 3 to 6 grids are used.
- Ensure the grids are created using the parent grid option in Petrel so that each grid has the same cell size and origin (and ideally the origin should be an even multiple of the cell size).
2. Wells
- One or more wells with a cleaned & edited sonic log (Vp) and/or a T-D curve derived from check shots. If the sonic logs are reasonably long, use those, otherwise use the TD curves.
- If you have generated synthetics, apply the resultant T-D curve to the sonic log to give a calibrated sonic log for the best well velocity data to use.
- Formation tops corresponding to the grids from above should also be present in each well, ideally with the same marker name.
3. Seismic velocities [optional]
- If they are in SEG Y format, load them into the Petrel project & they are then easy to import into the Velit model. Later version of Velit support both SEG Y and ZGY (realized) formats.
- If the velocities are ASCII files, they need to be reformatted into columnar format. Velit has a tool to do this – if you can send me an example file, I can record the steps on how to reformat the files for you (this will save time during the WebEx).