How can I change the primary phase from oil to gas? It seems to be by default set to oil?

That’s correct—by default, the primary phase is set to oil. 

However, if you create a new profile for the same well, you can set gas as the primary phase for that profile. The reason you can’t change the primary phase in the existing profile is due to differences in the input type conditions. We plan to improve this functionality in future versions, but it’s not a current priority.

Additionally, if you combine a gas well with the “start at cut-off” feature, you may need to define a small amount of oil rate for the well to ensure correct timing. This is another area we aim to enhance in later versions.