The negotiating approach Larry suggested is worth a try but, whether you obtain any of the mineral interest or not, as a condition of buying it I’d insist that the seller’s deed to you include a full waiver of the surface rights to the property. In that way the seller could retain control of the mineral interest, be able to lease it and benefit from any future production, but you would be assured that drilling or production could only be done by directional drilling, or pooling, and not involve the surface of the property you are buying.
I would have that deed wording drafted or reviewed by an attorney, and keep in mind that the seller can only waive the surface rights regarding the share of the mineral interest they actually own. If part of the mineral interest was reserved when your seller acquired the property, or at some earlier point in the chain of title, the waiver from your seller wouldn’t fully protect you. Title company’s review and issue of an owner’s title insurance policy doesn’t cover the mineral interest unless specific riders are added to the policy. The title report you receive prior to closing may disclose prior leases or inclusion in producing units but it typically won’t verify the ownership of the mineral interest.