Oil and Gas leases v Royalty interest deed/lease

Hello, my sister and I inherited overriding royalty interests in Upton and Scurry counties. We have the original deeds/leases (dated 1948 and 1951 when Grandpa acquired them) however, I am trying to locate the oil and gas leases to understand what conditions apply to new horizontal wells being drilled on our Upton County ownership. The operator is not being helpful and has made numerous mistakes (including overpaying me and underpaying my sister) and also not paying interest owed. They are a large company but we have dealt with 3 division order analysts in 18 months. They have been responsive to some degree but come across as being overwhelmed.

I live in Maine so the McCamey courthouse is a trek - what type of specialist should I be asking to help me with this?

I am a NARO Texas member which has been really helpful but I missed the convention this year due to having an operation (minor) otherwise I would have gone to McCamey and searched myself.

Thanks for any advice