The presence of legacy oil and gas production infrastructure,including wells and pipelines,sometimes conflicts with present and future land use.Often,the infrastructure has deteriorated with time and is now concealed by vegetation;it must be located before evaluation,plugging,or removal activities can take place.This study evaluates the efficacy of drone magnetic surveys for the rapid,low-cost detection and mapping of wells and pipelines.Results of this study demonstrate the utility of drone magnetic surveys for accurately locating concealed oil and gas wells.Some state oil and gas regulating agencies and private sector companies now routinely use drone magnetic surveys for locating unmarked wells.However,the magnetic method relies on the presence of a steel well casing,which is not always present,having sometimes been removed for metal recycling or reuse.Drone magnetic surveys for locating buried steel pipelines are significantly more challenging than well location surveys because the magnetic anomaly from buried pipelines is discontinuous and less intense than well-type magnetic anomalies.This study determined that drone magnetic surveys can locate steel pipelines ≥ 2 in.diameter buried 1 m deep without a trace current if flown at altitudes of 10 m AGL or lower.Low-altitude flight brings the drone and sensor into potential conflict with ground-based objects,which limits drone pipeline mapping surveys to open areas without trees,overhead utilities,and buildings.
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