Any wells that are currently operating are most likely owned by someone other than the current property owner. The well owners pay a royalty to the property owner. If the land changes hands the wells are not part of the package but the royalties from those wells would be. As for future wells, if they have the rights then they can drill away.
All this is conjecture and may or may not reflect reality, the property owner may be a wildcat driller and does,in fact, own the wells, and anything can be renegotiated.
So who the heck really knows?
Anyway, worst case, this looks like a good pinky gamble to me.