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T. R. Falconer – Antarctic Research Centre, Victoria Univ. of Wellington, New Zealand
A. R. Pyne – Antarctic Research Centre, Victoria Univ. of Wellington, New Zealand
J. Cowie – Antarctica New Zealand, Christchurch, New Zealand
D. Huey – Stress Engineering Services, Inc., Houston, Texas, USA
J. Leitch – Antarctica New Zealand, Christchurch, New Zealand
M. Mitchell – OPUS Engineering, Christchurch, New Zealand
B. Webster – Webster Drilling & Exploration Limited, Porirua, New Zealand
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In 2006/07 in McMurdo Sound, Antarctica, the ANDRILL drill rig successfully cored to 1285 metres below sea floor with 98% recovery, from an 82-m thick ice shelf platform overlying 850 m of water. The drilling system was developed with a mix of minerals coring technology and innovative custom-built components. Technological challenges overcome at the McMurdo Shelf (MIS) site included: the development of a hot water drill that utilized seawater heated to 90°C under pressure up to 1200 psi; the maintenance of a sea riser access hole through the ice shelf for up to three months; a lateral platform movement rate of 100m/year due to ice shelf flow; and vertical tidal movement of up to 1.7m.
Future proposed drill sites include locations with significantly thicker shelf ice, and lateral movement rates of 750 m/year and higher. In developing drilling strategies for these locations, the major challenge will be determining how to achieve target depths within allowable operational limits of sea riser and casing bending. Options under investigation include sea floor re-entry, accelerated drilling and multiple holes.
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McMurdo Ice Shelf Site
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Drilling Dates
Oct 2006 – Jan 2007 |
Final Depth Drilled
1285 mbsf |
Water Column
916 m |
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Target Depth
approx. 1200 mbsf |
Ice Shelf Thickness
approx 82 m |
Core Recovery
98% |
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References:
Huey D.P. et al. (2004), "Final Report: Analysis of proposed 6-inch Pipe and Couplings for ANDRILL Sea Riser," Stress Engineering Services, Inc. Report contract submitted to Antarctica New Zealand, Christchurch, N.Z.
Naish, T. and Powell, R. (2006), "ANDRILL McMurdo Ice Shelf Project Scientific Prospectus," ANDRILL Science Management Office, Lincoln, Nebraska, USA.
Robinson, N. and Pyne, A. (2004), "Water Column Current Profile Analysis from beneath the McMurdo Ice Shelf at Windless Bight and under the sea ice in Granite Harbour, Antarctica," Antarctic Data Series No. 26, Antarctic Research Centre, Victoria University of Wellington.
For more information on the Andrill Ice Shelf Platform Drilling Project, download the pdf. |
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