AIRGrav.
Airborne Inertially Referenced Gravimeter. The only purpose-built airborne gravimeter currently flying commercial surveys, designed for the airborne environment.
The AIRGrav gravimeter is mounted on a three axis inertially stabilized platform with high resolution Differential GPS (DGPS). The gyro stabilized platform makes the system far less affected by horizontal accelerations than systems using modified sea based gravimeters.
Terrain corrections are computed from an existing digital terrain model or from terrain data acquired during the survey itself, and no near station corrections are needed. Production conditions include offshore surveys, constant altitude over rolling terrain, loose drape over high mountains above 3,000 m, and moderate to severe turbulence.
The service runs end to end: survey planning, data acquisition, preliminary processing in the field, final processing to terrain corrected Bouguer gravity, a comprehensive technical report, and integrated interpretation.
Interrogate the field.
Move over the field to read it. The value range is illustrative of the Turner Valley case below, where anomalies under 2 mGal correlate with known oil and gas fields. The published evidence for AIRGrav is in the technical papers.
0.3 mGal of noise, over 12,000 line km.
South of Calgary, SGL flew a combined gravity and magnetic survey of more than 12,000 line km: east west lines at 250 m spacing, north south tie lines at 1,000 m, across a block 60 km north to south.
Noise was calculated at 0.3 mGal, and anomalies under 2 mGal correlate with known oil and gas fields. That is the standard the probe above is scaled to, and the standard the parameter table below is built on.
Typical AIRGrav production.
| Platform | Speed | Line spacing | Resolution | Production |
|---|---|---|---|---|
| Fixed wing | 120 kt | 1,000 m | 4,000 m | 500 km2/day |
| Fixed wing | 95 kt | 300 m | 2,200 m | 150 km2/day |
| Helicopter | 50 kt | 200 m | 1,100 m | 100 km2/day |
| Helicopter | 35 kt | 50 to 100 m | 700 m | 30 km2/day |
Accuracy: 0.2 mGal RMS throughout. Speeds, spacings and production from SGL's published AIRGrav parameters.
Gravity is one of seven.
AIRGrav flies in combination with magnetic and radiometric instruments on the same pass. The full method set is on the Services page.