HYBRID UAV AEROMAGNETIC SURVEYS FOR ORPHANED WELL DETECTION AND CLASSIFICATION

A significant number of abandoned oil and gas wells in the Continental US are considered orphaned as they lack proper records detailing their location, plugging and abandonment procedures, or current condition of the wellsite. Orphaned oil and gas wells may pose a significant threat to the communities and the environment in which they reside. If these wells were improperly plugged when abandoned, they may be responsible for continuing natural gas and co-emitted toxic gas and fluid release, resulting in air, surface, and groundwater contamination. Recent investments to infrastructure within the United States have included funding to combat excess methane emissions from known abandoned wells. However, any wells drilled prior to regulatory requirements on precise location documentation need to be located and prioritized for remediation, presenting a challenge to state and federal regulators.

Regulatory agencies tasked with locating orphaned wells deployed a number of techniques ranging from visual surveys to terrestrial and aerial geophysical surveys targeting magnetic anomalies associated with well casing at depth. Visual and terrestrial geophysical surveys have limited utility, as they remain time- and resource-consuming. The adoption of low-altitude aerial magnetic surveys relying on unpiloted aerial systems (UAVs) in wide-area surveys, pioneered by the authors, was a critical development allowing to dramatically improve well detection and subsequent identification efforts on the ground. To develop a robust geophysical methodology for well location, identified wells were assessed for emission potential. A remarkable correlation between the well’s magnetic signature and its potential to act as a high-volume source of methane emission was identified, allowing to formulate a framework for remote well prioritization for remediation. We present evidence of a strong correlation between the magnetic field strength of each well and its potential to emit methane and define a traffic light framework for initial wellsite remediation prioritization. This allows stakeholders to determine a priority for each well in terms of classification and remediation, reducing time, equipment, and labor costs associated with remediating orphaned oil and gas wells.