Ice Sheet Drilling by Soviet Antarctic Expeditions

Scientists of the Leningrad Mining Institute and of the Arctic and Antarctic Research Institute have developed fundamentals of the theory of the process of drilling by melting of open holes. A series of electrothermal core drills used with a cable has been manufactured. Two drilling rigs have also been developed and manufactured: a stationary one for deep drilling, and a mobile one for drilling to 150 m.

The deepest borehole at Vostok Station is 952 m. Core recovery was 99 per cent. The core diameter is 125 mm, and the borehole diameter is 180 mm.

Geophysical and geochemical studies in the boreholes have been made together with observations of ice-sheet dynamics and ice rheology.

The Arctic and Antarctic Research Institute has developed and successfully used lightweight electrothermal core drills for sinking boreholes in warm mountain glaciers without pumping out the water. In addition, thermal drills for drilling without core removal in warm and cold glaciers have been developed. Depths of boreholes in warm glaciers (with and without core removal) and in cold glaciers (without core removal) are 200 m and 80 m, respectively.

At the present, an electromechanical core drill is being tested in laboratory and field conditions, thermal core drills for a non-freezing fluid-filled hole are being developed, effective fluids are being selected, a system of removing ice chips and meltwater from the borehole is being developed, and the equipment for drilling to 4000 m is being designed.

Preparation is underway for drilling a deep borehole at Vostok Station in the 1977-1978 season.