Good advice from both. My property is West of yours.
I have had written offers to lease from $5000-6000 per nma. Your offer is a low ball trying to steel your lease and will then sell to an oil company for large dollar amounts. Don't do anything without an attorney representing you as there are more lease concerns in a contract than what a landman will present you, don't sign any documents from the interested party. You have heard of people flipping house for profit, that is what these low ball offer are trying to do to your mineral rights.
There have been many comments in this forum about minerals, etc,, you should go back several pages and read what has been discussed maybe a year or two.
3 year lease, no option and 25% royalty. Also new leases are being negotiated by field formation. Don't give a total depth lease "from the surface of the earth to middle earth or you will give up valuable mineral rights. Current leasing in my area is for the Wolf Camp formation.