I’m not an expert but I am a mineral owner in your general area. Unless the original lease was negotiated by my expert oil and gas lawyer, I definitely would not sign an extension. IOW, if I had pretty much signed the lease handed to me by the oil company, I’d be verrrrry happy to get out of that lease! Oil company leases naturally favor the companies, often bigtime.
Even if that lease had been negotiated by my lawyer, I still might not want to extend it. Some important legal things have changed in the last few years! You want an expert to make sure that your original lease, or a new lease, has precise language to keep the oil company from deducting expenses against your production. The wordage that used to work in leases often no longer does and mineral owners are suddenly finding that substantial sums are being deducted from their oil revenues.
In addition, bonuses have gone up quite a lot in your area in the past five years. Bonuses can go from maybe $8,000 to $12,000 or even $15,000 an acre now, three-year lease, 25% royalty.
We never negotiate a three year plus two year lease. The owner never wins with that scenario. Longest we will go is three years. But leases can be as short as a year (with lower bonuses, of course).
If you need a good mineral lawyer, we’ve used Wade Caldwell and been very happy with him. He is listed on this site somewhere. Best luck to your grandmother!