A drone and aerial magnetometer prepare for takeoff.

Magnetic surveys measure Earth’s magnetic field variations produced by magnetized or magnetically susceptible targets like buried well casings, drums, tanks, pipelines — anything made with iron or steel or that has been fired or heated. Surveyors often use an aerial magnetometer suspended from an unmanned aerial vehicle (UAV) or drone to access areas of dense vegetation or rugged terrain when suspected targets are in these hard-to-reach areas. The UAV or drone flies as low as possible while remaining above structures or trees, enabling the surveyor to rapidly collect magnetic data over hundreds of acres per day across terrain that would otherwise be unreachable!

Orphans No More: Finding Abandoned Oil and Gas Wells

A drone uses an aerial magnetometer to collect data from high above the tree line.

Over 3 million abandoned or orphan oil and gas wells are scattered across the United States (over 750,000 in Pennsylvania alone!), many installed during the first oil boom in the late 1800s and early 1900s. Once depleted, the owners just walked away – some threw rocks down the well, some put rocks over the well as a makeshift cap – but most were abandoned and became overgrown or buried with time. Many orphan wells are the source of methane emissions or groundwater contamination. Several states have identified an urgent need to locate these wells to cap or decommission them properly. But how is it possible to cover such large swaths of land while looking for these tiny, yet in plain view, ferrous targets? Aerial magnetics has been a game-changer in this challenging quest!

A sample heat map identifies targets.

RETTEW uses an aerial magnetometer suspended from a drone to fly over several thousand acres in the eastern United States to detect orphan wells. Typically, we cover a few hundred acres per day, flying 100 to 150 feet above the ground surface, and, with the property owner’s permission, create a magnetic “heat map” (see example) that identifies ferrous targets at or below the ground surface. Our ground crew uses the coordinates of unidentified features (possible wells or other buried ferrous material) to navigate to the targets and dig to expose them. Since beginning this project, we have flown more than 5,300 acres and detected over 800 undiscovered wells, a great start to remediating an enormous problem!

Meet Mark Snider

Survey/GIS Team Lead

Meet Mark Snider, a multifaceted Team Lead whose career as a surveyor and FAA-licensed drone pilot has been filled with unusual experiences. Read on to go “beneath the surface” and discover what Mark says is his most unique experience on the job.