A claim with an oil company - re 1936 deed

An oil company which I have made a claim based on my grandfather’s 1936 mineral deed said they based their title opinion on the 1851 Patent from the State of Texas to October 3, 2011. Does anyone know anything about this patent? I would appreciate any help. Thank you so much.

Could that be a fancy way of saying that the company believes it has done exhaustive title research?

Have you followed the chain of title from your grandfather's mineral deed to the present?

Hi AJ - YES - I have all the docs and the filing records with Gaines County showing the chain of title. Thx AJ for your reply.