Because there were no reservations in the deed any and all mineral interest the previous owner owned transfers to you. You need to send a copy of your deed to the operator of the well(s) and have them make a change of ownership so you can be placed in pay to start receiving your royalties. If you don’t pay the taxes the mineral interest will be put up for auction and sold. The taxes are only a small portion of the revenue you should be receiving so you’ll want to pay them. The county can tell you who the operator is and their contact information.