Hi Cindy! It might not be possible to match the leases with the tax statements right away. The tax statements for mineral interests start with 9999 and they don’t match up with any given surface tract. However, the tax rolls are online and you can track the current tax tickets back to where they changed hands, and even back to where they were originally separated from a surface tract. It takes a while, but it’s doable. Once you know the surface tract, you can follow it forward in time and look for leases in the names of the various surface owners until you get to the leases you have.
The property that was never transferred may need an ancillary estate done. Again, it’s going to take research and some paperwork, but it’s doable. Good luck, and have fun with this! Oil and gas is fascinating.