“be very sure there is not an easement”
True, and watch whether you own mineral rights or not on any property you own.
It's so complex that there are ARMIES of lawyers who specialize in pipeline routing cases.
I suspect the term "eminent domain" doesn't exactly apply here since the company that owns an existing easement is probably operating under municipal powers granted by Oklahoma DECADES back and has already acquired an easement for which it pays regular rents and fees. Trans Canada merely owns that company.
The people making noise probably have a lawyer who already knows this and is prepared to do the job for which he has been hired. That would be to RAISE THE RENT and guarantee that the property owner has unimpeded rights to cross over the line right of way from one part of his property to the other.
My development has a gigantic pipeline crossing it. It was put in back during WWII for the purpose of bringing Texas and Oklahoma Oil to Refineries in Pennsylvania and New Jersey. They call this one "The Big Inch". Currently this line is used to pump mostly natural gas, the main oil moving job having been passed off to different lines elsewhere.
This thing runs through a residential development through people's backyards. It cuts through our association's property ~ and at the time the development was being reviewed by the county planners the lawyer had to get a specific statement from the line owner that WE could cross THEIR easement.