What are some good ways to create synthetic velocity models?
The following describes the workflow to create a Vo+kz velocity model with varying gradients between horizons for the purpose of time/depth conversion.
Create a simple V0 model
![Create a simple V0 model](https://media.screensteps.com/image_assets/assets/003/311/882/original/6ebc82d5-9e96-4dd4-acba-d10720a60961.png)
- In the Process tab, click on the Add icon and select New Process.
- Create a Volume Maths process and type a Name for the process. Click OK.
- In the Details Panel, at Formula, type the formula 1500 to create a velocity model at a constant value of 1500.
- Under the Output Extents section, select a 3D survey.
- Enter the appropriate Inline and Crossline extents for the model.
- Models can be created in TWT or TVDSS, depending on the domain selected in the output extents.
- The velocity model will appear in the Volume tab.
Assign a velocity class to the model
![Assign a velocity class to the model](https://media.screensteps.com/image_assets/assets/003/311/884/original/91e5c850-2496-4e53-822e-f66915edb5f8.png)
- In the Control Panel, open the Volume tab.
- Double click the velocity volume or right-click and select Configure 'Volume'.
- At Class, select Velocity (Interval) from the drop-down list.
- Click OK.
Create a simple V0 + k(z) model
![Create a simple V0 + k(z) model](https://media.screensteps.com/image_assets/assets/003/311/886/original/a58645ea-e3ce-4241-9261-8a2f87ca1f34.png)
- In the Process tab, click on the Add icon and select New Process.
- Create a Volume Maths process and type a Name for the process. Click OK.
- In the Details Panel, at Formula, type the formula 1500+1.05*tvdss_m.
- Under the Output Extents section, select a 3D survey.
- Enter the appropriate Inline and Crossline extents for the model, and select TVDSS as the output domain.
- The velocity model will appear in the Volume tab.
- In the Volume tab, double click the velocity volume or right-click and select Configure 'Volume'.
- Change the Class of the volume to Velocity (Interval) from the drop-down list.
Create a layered V0 model
- Create a Window Model using constants or horizons (see Creating a Window Model).
Note: If you are creating a velocity model in depth, you must create a window model in depth. - In the Process tab, click on the Add icon and select New Process.
- Create a Velocity Model (From Well Checkshots) process and type a Name for the process. Click OK.
![](https://media.screensteps.com/image_assets/assets/003/311/890/original/85e73e6a-091b-4457-9a42-74da8e28713a.png)
- Select the Windowing Model that you have created.
- Under the Output Extents section, select a 3D survey.
- Enter the appropriate Inline and Crossline extents for the model.
- Under the Per-Layer Settings section, change the Calculation types to User-specified constant and enter an appropriate value in the adjacent box.