
Your inquiry does not set forth sufficient facts from which it can be concluded that the lease is invalid. We do not know the relationship of the person who solicited your signature to the oil company (employee? independent contractor? outside attorney?). Moreover, there is the very obvious problem that you actually executed, and intended to execute, the document, so you are bound by it even if the notarization is defective, and the oil company may be able to compel you to re-execute a validly notarized copy of the same lease.
If you want to get out of the lease, you should consult an attorney to see if it is possible. It seems unlikely from the facts you post. This is not legal advice.