Locating undocumented orphaned oil and gas wells with smartphones

Abstract

It is estimated that about 3 million orphaned and abandoned oil and gas wells exist in the U.S. that are leaking greenhouse gases and dangerous chemicals into the environment and thus pose both environmental and health risks to the public. Although about 130,000 of these wells have been identified, a large portion of them have either missing or incomplete documents making them difficult to locate and plug. Most of these wells have been out of use since early 1900s and may be missing wellheads or are rusted and covered by overgrown vegetation. Therefore, they are difficult to visibly notice and locate. However, the majority of them used one form of iron alloy casings. Such alloys are magnetic material that can be sensed by magnetometers. Most smartphones nowadays come with a magnetometer (as a compass) sensor. Here we utilize an iPhone 12 mini for the purpose of locating two abandoned wells (one with an exposed wellhead and one without any visible signs at the surface). We designed a simple unmanned aerial vehicle (UAV) survey setup where the iPhone 12 mini was put inside a custom-made sleeve and hung from a DJI Phantom 4 drone at about 1.5 m below the drone. We surveyed the two sites by flying the drone at three different altitudes, 10 m, 15 m, and 20 m above ground level (AGL). Our results show that at altitude of 10 m AGL the iPhone 12 mini magnetometer could pick the magnetic anomaly of either of the wells at intensities ≥52 μT; sufficient to accurately locate the wells. At altitude of 15 m AGL the iPhone 12 mini was able to locate the wells but within ∼5 m radius of the actual wells' location, and it was unable to detect any magnetic anomalies at 20 m AGL. This UAV setup cost about $2000 and was simple to operate. No data processing was done to create the magnetic maps showing where the wells were located in the survey areas. Thus, this setup is accessible to a broad range of users who are looking for ways to locate orphaned wells fast and easily.