Hi Ann -
The County Offices are not allowed to answer the types of questions you have or to offer legal advice. They are not Attorneys and the Counties' Employees are not allowed to put the County in any position of possible liability.
"Jaguar" was probably the Shell Oil Company Prospect Name. If so, that wouldn't have anything to do with your interests.
If you will send me your legal description I will see if I can map your lands out for you and tell you what is going on out there. Please accept my offer to become "A Friend" on The Forum. You can send it to me privately that way.
As far as Sales or Purchase Prices go, buying low and selling high is one of the founding principals of our nation. You, as the potential Seller, need to educate and protect yourself - which appears to be what you are doing. Smart Girl.
If there are producing Wells on the property, then there are various ways to come up with a purchase price. You can have an expensive Reserve Study prepared by a Petroleum Engineer (or one mutually agreed upon between you and any potential Buyer), but many people consider that trying to sell oil still in the ground.
The simplest way that I am familiar with is to take the average of the most recent 3 month's worth of royalty checks and multiply that by from between 36 months (3 years) to 60 months (5 years). The difference being based on the projected future or remaining life of the Well(s).
If there are no producing Wells on the land, then the sales or purchase price is whatever you can get someone to pay you for it. There is no magical mathematical formula to rely upon to come up with a purchase price. Some people will use "3 times the last leasing Bonus Payment" as an offer, but I don't especially agree with that.
To some degree you may be able to use production and royalty figures from nearby Wells, but even that will be only so accurate.
Send me your legal description and let's see what's going on in your area first.