To which extent does the EIA study represents a governing factor in oil & gas projects?

I personally think such study is definitely important considering environmental impacts when deciding whether or not to proceed with a project.
Secondly, in case such study is not made and it may result to major delays or maybe failure of the project.
So its always a good idea to have this at planning stage so that any diversions, amendments etc.
can be made at right time

I am not in the sector of the oil and gases, I am in the sector of IT, but any technical study make you expert in that technical field but not in the managerial field.