Natalie Pekney and Jim Sams are hunting across the United States for a treasure they’d rather didn’t exist: undocumented oil and gas wells, some so old that foliage has overgrown them and hidden the environmental hazards they pose. Like any good explorers, the team needs reliable maps—ones they’re constructing, in part, with historical documents.

Old photos and drawings, paired with new data gathered by remote sensing, help Pekney, an engineer with the U.S. National Energy Technology Laboratory (NETL), and Sams, a geologist with the information technology company Leidos, navigate as if they were some of the country’s earliest oil and gas prospectors themselves. “When you go out into the field and attempt to find wells, it can