Importing Velocities

Owned by Erlend Kvinnesland
Last updated: Sept 11, 2012 by Former user (Deleted)Version comment

Introduction

Geocap supports different velocities formats. The import method varies depending on the format:

  • Stacking velocities - ASCII reader
  • TGS format - Generic import
  • EssoV2 format - ASCII reader

All velocities can be imported into Generic folders in Geocap.

Stacking Velocities - ASCII

Stacking velocities can be imported with or without navigation using the ASCII reader. If the velocities are imported without navigation the reference to geographical position can later be restored by looking at the seismic line name and SP.

Without navigation

The Stacking Velocities (no navigation) menu is a pre-set version of the ASCII import menu with settings to read stacking velocities without navigation (no X's and Y's).


Example of stacking velocity import without navigation

Note that the velocities are defined in time-velocity pairs, locked to a SP and line reference. The goal of the import is to create a dataset for each line, where each cell in a dataset is a SP consisting of several time-velocity pairs. This is achieved by using the Separate cells and Separate data sets as indicated in the image.

Make sure each column numbers are set correctly. The preview of the five first elements should give you a good indication of this.

Before you import, make sure the Schema is set to Stacking Velocities

With navigation

Velocities with navigation is imported exactly the same way as velocities with no navigation, except for that there are 2 more columns to for X and Y.

Since the velocities have no navigation it is necessary to assign navigation after the velocities have been imported.

TGS format

TGS Nopec has created a special format for stacking velocities. This format can be read using the Generic import menu, and setting Format to TGS.

EssoV2 format

The Stacking Velocities, ESSOV2 menu is a pre-set version of the ASCII import menu with settings to read the EssoV2 format.

Note that the EssoV2 velocities do not have navigation. This means that it is necessary to assign navigation after the velocities have been imported.

"Generate Velocity Profile"-format

In order to use the velocities in the command Generate Velocity Profile the velocity data should have the following form:

  • Z value is time.
  • Velocity data is in the scalars field, or it may be in field data Velocity.
  • Shot points in field data SP.
  • 2D line numbers in field data 2Dline.
  • Separate cells by shot points.
  • One seismic line per data set.
  • Import dataset with schema Velocity.