Texas Purchasing rural land

Greetings. My family and I are under contract to purchase 40 acres in Austin County, Texas. My dad is a land owner and is a strong advocate of making sure we have the mineral rights (or a percentage) before I sign the contract. I am not opposed to this, however should this be a deal killer for the land purchase. The seller is giving up all surface rights, but their first offer seems like they are wanting to keep the percentage of mineral rights that they own already, which I think is 50%. To be clear, we would not want any company drilling on our property at any point. So I guess my question is, if we were given a smaller percentage of mineral rights, let’s say 10%, would that be enough for us to stop any kind of lease from happening with an oil company? Thank you