Are oil royalties reported in the state where the wells are located, or the physical location of the companies of whom are supplying the royalty payments?

Oil royalties are reported in the state the wells are located (you would file as a nonresident)  and on your resident state, NOT where the payers are. 

Please file nonresident state first, if you are required to file.  If you have paid any tax, your resident state will give you credit for taxes paid to another state...