Locating undocumented orphaned oil and gas wells with smartphones

Majority of the estimated 3 million abandoned oil and gas wells in the U.S. have missing documents and lack surface equipment making them difficult to locate. However, most of them have casings made of iron alloys which are magnetic and can be sensed by magnetometers. Here we utilize an iPhone 12 mini smartphone as a magnetometer to locate two abandoned wells. We designed a simple unmanned aerial vehicle (UAV) survey setup where the iPhone 12 mini was hung from an inexpensive small drone. We surveyed the two sites by flying the drone at altitudes, 10 m, 15 m, and 20 m above ground level. Our results show that at altitude of 10 magl the smartphone 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 magl the smartphone could locate the wells within ~5 m radius of the actual wells’ location, and it was unable to detect any magnetic anomalies at 20 magl. Simplicity of the setup, minimal required scientific knowledge and low cost of the setup makes this setup an ideal tool for locating orphaned wells by citizen scientists.据估算，美国境内共有300万口废弃油气井，其中绝大多数缺失相关档案资料且无地面配套设备，因此难以定位。但这类井大多带有铁合金制成的套管，该套管具有磁性，可通过磁力计（magnetometer）探测。本研究采用iPhone 12 mini智能手机作为磁力计，完成了两口废弃油气井的定位任务。我们设计了一套简易的无人机（unmanned aerial vehicle, UAV）勘测方案，将iPhone 12 mini挂载于一台廉价小型无人机下方。我们分别在距地面10米、15米及20米的高度操控无人机飞行，对两处作业站点开展勘测。实验结果表明，在10米距地高度下，这款智能手机磁力计可捕捉到强度≥52微特斯拉（μT）的单井磁异常信号，足以精准定位废弃油气井；在15米距地高度下，智能手机可将井位定位误差控制在实际井位周围约5米的范围内；而在20米距地高度下，则无法探测到任何磁异常信号。该方案操作简便、所需专业科学知识门槛极低且成本低廉，可成为平民科学家定位无主废弃油气井的理想工具。