Airborne gravity gradiometry for exploration geophysics- the first 5 years

Abstract

Gravity Gradiometry for exploration geophysics became reality after declassification of the Bell Aerospace Full Tensor Gradiometer system in the mid 1990’s. Initially the system was deployed seaborne for hydrocarbon exploration. Airborne applications ensued after improvements in acquisition procedures and data processing. Airborne surveys are typically flown with a Cessna Grand Caravan. - Post processing accuracy levels are in the order of 3 E over wavelengths of 400 meters. Data processing is a five stage process. These include: high rate software to remove self gradient effects, terrain correction, a stage with redundancies and correlation to filter out obvious spikes and shifts, manual levelling to take out drift effects and “Full Tensor Processing” to remove uncorrelated noise in the tensor components. Slowing down the platform improves spatial resolution. This is currently observed with an instrument operating on a Zeppelin NT airship for De Beers exploration in Botswana. The results of this method are comparable to high resolution ground gravity offering less than 2 E over 100 meter wavelengths detectability.