The original lessees in most cases are just brokers, many of which are long gone. It really depends on whether your lease was drilled or not. To be fair, a majority of leases in Tarrant County have been drilled and are producing / active.
Were the minerals ever reserved between the time they were leased and your purchase?
You will need to use the RRC GIS website to look at wells and see if any are close to you: https://gis.rrc.texas.gov/gisviewer/
All of the deed records are free here: https://tarrant.tx.publicsearch.us/
If you find a well close to you, identify who the operator is and then contact them. They will ask you for a chain of title, which you should be able to get through the other link I provided for Tarrant County Deed Records. There is no need to pay for copies, just download the documents as PDFs. You don’t need certified copies for this purpose either.