Sticking deep ice core drills: Why, and how to recover

• Main Authors: Niels S. Gundestrup, Sigfus J. Johnsen, Steffen B. Hansen, Hitoshi Shoji, Pavel Talalay, Frank Wilhelms
• Format: Report
• Language: English
• Published: University of Copenhagen, Department of Geophysics/University of Copenhagen, Department of Geophysics/University of Copenhagen, Department of Geophysics/Kitami Institute of Technology/Department of Descriptive Geometry, St. Petersburg State Mining Institute/AWI, Colombusstrasse 2002
• Subjects: Greenland; Freed; Antarc*; Antarctica; EPICA; GISP; ice core; Memoirs of National Institute of Polar Research; NGRIP; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2441; http://id.nii.ac.jp/1291/00002441/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2441&item_no=1&attribute_id=18&file_no=1

The GISP deep drill became stuck in 1981,but was free the following year. The NGRIP/EPICA deep drill has suffered from two big setbacks : The drill is stuck both at NGRIP in Greenland and at Dome C in Antarctica. Both events occurred in a period with routine drilling and high productivity. The reasons for the two events are believed to be different, but the chosen bore-hole liquid seems to be problematic. The densifier can adhere to the surface of the ice cuttings, making fine ice cuttings to sink in the liquid, in spite of a liquid density of 935kg/m^3. In spite of changed procedures and modified constructions, the drill became stuck again at NGRIP. It was freed using glycol, making use of both the temperature and temperature gradient in the hole.