A huge drill borrowed from an oil company has joined two others digging through the 630m (2,060ft) of rock separating the miners from the surface.

从一家石油公司借来的巨大钻机加入到另两个钻机之中，为的是把隔开矿工与地面的630米(2,060英尺)岩石挖穿。

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Bissell hired Edwin Drake to drill for rock oil, not salt, and in 1859 Drake found what Bissell was looking for.

FORBES: Magazine Article

Drillers have learned to drill horizontally into long, thin seams of shale and other rock that holds oil, instead of searching for rare underground pools of hydrocarbons that have accumulated over millions of years.

FORBES: IEA Report: USA Set To Become Number One Oil Producer By 2020-Energy Independent By 2035