Case study by SPH Engineering · Magnetometry · Oil and gas
Drone magnetometry locates abandoned gas wells in agricultural wetlands
Before a wetland restoration project in California could go ahead, the team had to find 25 abandoned gas wells whose recorded positions were uncertain. Targeted drone surveys with SPH Engineering's MagNIMBUS found 22 of them, plus seven old pipelines.
The challenge
The site, used mainly for rice and seasonal waterfowl hunting, was being restored as wetland. California keeps a GIS database of abandoned gas wells, but its locations vary in accuracy. The California Department of Conservation listed 25 wells in the project area, and their exact positions had to be confirmed before work could start.
- Many wells were no longer visible because of farming and sediment.
- Irrigation channels and metal farm features added magnetic noise.
- Wet ground limited access for ground surveys.
- Surveying all 2,200 acres the traditional way would have been slow and disruptive.
The solution
Instead of covering the whole site, the team flew 500 ft × 500 ft blocks centred on known and suspected well positions. A DJI Matrice 350 RTK carried SPH Engineering's MagNIMBUS with the SkyHub onboard computer, and UgCS kept low flights and line spacing consistent: about 5 m above ground and about 5 m between lines.
Fieldwork took four days: three to cover all 25 locations and one to revisit features found in processing, with about 35 flights averaging 20 minutes. SPH Engineering gave remote support and used GeoHammer for quick checks. Full processing in Oasis montaj corrected GNSS time lag, motor interference, stationary artefacts and daily magnetic variation from a base station.
The results
- 22 of the 25 wells were detected.
- Two locations showed no anomaly inside the first 500 ft × 500 ft block.
- One well was partly masked by nearby irrigation infrastructure.
- Seven horizontal pipelines from old gas infrastructure were found.
Focusing on target blocks cut field time while still giving reliable results for restoration and land-use planning.
Where this applies in India
- locating old well casings and buried steel lines in mature oil and gas fields;
- checking farmland or wetland for buried infrastructure before restoration or construction;
- verifying recorded positions of buried assets where records are uncertain;
- industrial land redevelopment where old pipelines may remain.
SPH Engineering's magnetometer training is also available through HobiTech.
The equipment, available from HobiTech
| Magnetometer | MagNIMBUS by SPH Engineering |
| Onboard computer | SkyHub by SPH Engineering with the SkyHub MagNIMBUS software |
| Flight planning | UgCS - Drone Flight Planning Software |
| Drone | DJI Matrice 350 RTK |
| Processing | GeoHammer (quick checks) and Oasis montaj |
Case study by SPH Engineering, published February 2026. This page summarises it in our own words; the survey was carried out by a project team managed by Michael Detwiler (formerly of Wood Rodgers), not by HobiTech. Read the original case study on SPH Engineering ↗
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