A Light-Weight Hot Water Drill for Large Depth: Experiences with Drilling on Jakobshavns Glacier, Greenland

Near the centerline of Jakobshavns Glacier, at a distance of 45 km from the calcing front, 4 holes were drilled to 1200 m - 1330 m depth, each taking 12 to 18 hours to drill. A few shallow holes were also drilled. Original diameters of the deep holes ranged from 120 mm to 180 mm depending on drill speed. Boreholes froze at a fast rate, e.g. a hole with a diameter of approximately 180 mm froze shut in less than 10 hours. Thermistors were installed in several holes and the temperature adjustment was recorded. The ice temperature decreases almost linearly fro -18 ^oC at 400 m to -22 ^oC at 1000 m depth.

The hot water drill consisted of a 6 m long drill stem with a diameter of 30 mm and 3/4 inch medium-pressure hose. The drill speed was controlled by a capstan-type motor winch. A water discharge of 3.6 m³/h was provided by 3 piston pumps, the water was heated to 58 - 76 ^oC by three to four diesel heating units.