Surface & minieral rights to land from 100 years ago, how do you reasearch?

[David Pennington]

I am purchasing a 3acre lot an hour outside Dallas which not only fails to convey mineral rights, but also gives "appurtenant rights to use the surface of the land" to someone back in 1925. 

I plan on splitting this land into two 1.5 acre lots as there is enough road frontage, but I'm concerned that someone could show up and want to start drilling in the backyard.

I think someone wanting to drill is unlikely for the following reasons:
- the original owners are probably dead and the ownership is split between inheritance to multiple people
- the lot is too small for them to mess with
- there is only a single active well/pump within 30 miles from what I can see online. This is not a good area for drilling.
- the lot is very close to the city limits and might be included within the next few years
- the rights were from a larger 40 acre tract that were from a larger 80 acre tract that were from a larger....

Nevertheless, I am curious if anyone has recommendations on how to research this?

(apologies for the misspellings in the post title)