Hi, Del -
Nope, mineral rights never go away. At least not in Texas.
Are you or either of their estates presently receiving any royalty checks? If so, they will help you to discover what properties you have in producing wells.
Beyond that, the least expensive way to discover what you own is to simply wait until a Landman contacts you about what you own.
It might take years, but it’s the right price. They’ll provide you the legal description(s) and copies of your Source Deeds (where your Grandfather either purchased or reserved minerals). Possibly even copies of their Title Notes or Title Runsheets, which set out the history of the land, as well. You can even include a provision in any leases you sign that they provide you with that information.
The issue is, do the Landmen know where to find you.
If either of your Grandfather or Father left a Will and it/they was probated, then you will need to obtain certified copies of the court matter and file them in each County your Grandfather purchased or reserved minerals in.
If neither or either of them did not leave a will, then you will need to prepare an Affidavit of Heirship and file that of record in every County your Grandfather purchased or reserved minerals in.
In either situation, make sure the papers include your name and current contact information - even if only as the person the Clerk’s Offices is asked to return the original(s) back to after filing.
One last item: Reeves County, Texas is really booming right now. It would be wise to have an attorney experienced in oil and gas law look over any lease you are offered before you sign.
OK, one last last item: If you will send me your legal description I will be happy to take a look at the area and tell you what’s going on.