Hole liquids and gaskets for the ISTUK deep ice core drill
Memoirs of National Institute of Polar Research, 49, p. 327-334, 1994.
N.S. Gundestrup, H.B. Clausen, S.B. Hansen and S.J. Johnsen
Geofysisk Afdeling, Niels
Bohr Instituttet for Astronomi, Fysik og Geofysik, Københavns Universitet
ABSTRACT.
Deep boreholes in polar ice sheets have to be filled with a liquid in order
to prevent hole closure due to the overburden pressure of the ice. In Greenland,
at ice temperatures of -32 C, the limit for open hole drilling is 400 m. In
Antarctica, a depth of 900 m has been obtained in an open hole. All drilling to
deeper depths needs to be performed in a liquid. The borehole liquid should have
a density close to that of ice, be non-toxic, available in quantities at
reasonable cost, compatible with the materials in the drill, non-aggressive to
ice, and have a low viscosity to allow rapid drill movement in the borehole. In
practice, no liquid has been available that can fulfill all the requirements. In
the past, ethanol/water mixture, DFA/Glycol, DFA/TCE, JET-A1/PCE, DFA/F113,
n-butyl acetate, and D60/F113 have been used. All liquids have their own
advantages and disadvantages, and the use of all have involved severe
compromises. In this paper, these ideal specifications are compared to those of
the actually used hole liquids.
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