New to all of this need guidance

My Dad asked me to seek some info. He just retired from Govt. service and owns along with the mineral rights 11 acres in North Atascosa County. In fact north of Lytle and almost at the tip. On the property there is an old oil well that may have been active in the early 80's. It has black oil residue and all over it and when we put an empty barrel over it with a weight, always the next day the barrel is knocked over. Just a half mile away there is a Lease and the Co. is Omni. Does anyone on this discussion believe there is any merit in exploring if we are possibly sitting on an opportunity and what are the next steps?