Have you tried requesting your families chain of title from the title opinion prepared covering your interest in the certain well you are looking for information on??? Sometimes the division order department will supply this.
I myself have been having trouble locating early title documents in several counties in Oklahoma because the records in several counties are only like 1992 forward. When I explain to the oil companies that I have put my own time into looking for the documents in the courthouse and online and fallen short with my search due to the information not being there, and I myself living in Texas, they seem to help me out with searching through their own records.
You can also just try to ask someone in the division order department to supply you with the vesting deed on how your cousin came into title.
I have a contact at Continental in the land department who helped me with an interest in Texas. If you would like I could see if she could put me in direct contact with the division order analyst or landman covering Custer County, OK, and see if they are willling to help?