Import velocity model

Import velocity model loads a depth velocity model stored in a SEG-Y file (.sgy / .segy) into a g-Space project. The velocity data is read through the standard SEG-Y reader, but the command lives on its own velocity menu rather than the seismic import.

Purpose

Bring an externally prepared depth velocity model into g-Space as a new velocity model. Each imported trace becomes a velocity function in depth, so the file is interpreted in the depth domain as post-stack velocity data.

Launching the import

In the Data manager, right-click the Velocity model root node and choose Import velocity model from its context menu.

[image: placeholder_Data_manager_context_menu_on_the_Velocit.png]

Step-by-step

In the Import depth velocity file dialog, select one or more .sgy or .segy files (filter Data files (*.sgy *.segy)).
Set the Trace header format so that the SEG-Y reader maps trace coordinates and geometry correctly.
Provide the coordinate reference (EPSG) information requested by the import dialog so the velocity traces are positioned in the project coordinate system.
Confirm to read the file. g-Space snaps traces to the nearest existing bins, builds a velocity gather in the depth domain, and derives the model datum from the data.
A new velocity model is created and set as current in the Velocity model tree, ready for use.

[image: placeholder_Imported_depth_velocity_model_appearing_.png]

Notes

The file is always interpreted as a depth-domain, post-stack velocity model, so the values in the traces should be velocities.
Because the standard SEG-Y reader is used, the same trace-header and coordinate-reference settings that apply to seismic import apply here.
Imported traces are matched to the project geometry by snapping each trace to the nearest bin, so a compatible survey geometry should already exist in the project.