Multi-technology Detection of Undocumented Orphaned Oil and Gas Wells: A Large-Scale Drone and Ground-Based Survey in Pennsylvania.

Hundreds of thousands of undocumented orphaned oil and gas wells are estimated to exist in the United States. These wells have no formal owner, and their locations and conditions are unknown. They pose risks to the environment, climate, human health, and safety, and they represent a potential source of methane. While drone-based magnetometry and methane surveys have been used for well detection, no study has systematically integrated these technologies with ground-based methods, multi-stakeholder coordination, and field verification into a single framework at this scale. We conducted a drone-based magnetometry survey over 12 km2 of hilly, forested terrain in Northwest Pennsylvania and identified 31 undocumented wells by regulator-led field verification, with methane emissions detected at three of the 31 wells. Several drone-identified magnetic anomalies (13%, n = 34) were revisited using ground-based magnetometers, indicating the potential presence of 15 buried undocumented wells. However, since the interpretation of both drone- and ground-based magnetometry relies on expert judgment, field verification remains necessary. The drone-based methane sensor detected elevated methane concentrations over forested areas, but emission sources could not be confidently attributed. This study presents the largest drone-based survey of its kind and introduces a multi-technology framework that integrates drone and ground-based magnetometry and methane measurements, along with regulator-led field verification, for systematically locating and evaluating undocumented orphaned wells in complex terrain.