Paid out royalties

My mother passed away in 2013 and American Petroleum has issued checks every year that are sitting in Oklahoma unclaimed property. Prior to her death she signed a pool agreement, but I cannot locate the paperwork and the Company that sent the letter is no longer in business. How do I find out who is issuing the royalty payments. All I know is that it is in Hidalgo County.

Do you have a legal description of the property in question?

No, but I'm working on that the Unclaimed property division will only tell me that it is from American Petroleum