Traditionally we have mapped the subsurface using surveys, carried out by large ships towing streamers through the water. However, this is expensive and time-consuming and can have safety implications, so Maersk Oil and partners have been exploring the use of airborne Full Tensor Gravity Gradiometry (FTG).
This method generates a detailed picture of the subsurface by measuring changes in gravity (or, to be precise, gravitational acceleration), which tell us about changes in the density of subsurface material. This can then complement existing seismic data to give a clearer, more accurate image of geological complexities of the subsurface.
We used one of BellGeo’s Basler Turbo BT67 aircraft (a converted DC-3T) with a Lockheed Martin FTG system.
The aircraft is ideally suited to fly low, slowly (about 110 knots) and steadily.