What due diligence is required for oil property?

[Marcus Brown]

A seller accepted an offer for a piece of land in east Texas, the land has a part of a refinery on it and a lease in place. The exit strategy is to resell the land, but I have no idea what to look at. Mineral rights and lease agreements? Environmental? I went to https://www.epa.gov/cleanups/cleanups-my-community , clicked on Texas, then entered Henderson County. There were no clean ups
listed, what else should I look for?