Andre Sougarret, mines manager for state-run copper company Codelco and on-site rescue coordinator, said that operation was stopped Tuesday while the drill head was changed.

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Martin Siegert points out that the water in the drill head will only be a few degrees above 0C as it enters the lake - it inevitably cools as it flows 3km down into a hole that is surrounded by ice at -35C.

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Soon after that, I got it in my head to drill my first well.

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Of the 25, 000 wells Weatherford International helped drill last year, the gnarliest was in the Knotty Head prospect in the Gulf of Mexico.

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The chairman of the Joint Chiefs of Staff, by mentioning that the joint drill had been in the works, was apparently trying to head off criticism that the United States was raising tensions by rushing warships into the troubled area.

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As the head of the company, Hayward became a lightning rod for public and political anger after the drill rig operated by BP exploded in the Gulf of Mexico in April.

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"We know how to drill it, but we don't know how to produce it yet, " says North American exploration head Raymond Wilcox.

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Rear Admiral William McRaven, head of the special forces now operating in the Sahara, says his men are much more likely to drill boreholes and build houses than to shoot at anyone.

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