Drilling into such an oil or gas reservoir presents a risk of the fuels shooting upward in an explosive and uncontrolled way.

在这样的压力环境下钻探石油或天然气，很可能会造成石油以无法控制的爆炸性的方式喷涌而出。

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Note that some horizontal Wells are designed such that after reaching true 90-degree horizontal, the wellbore may actually start drilling upward.

请注意，一些水平井是这样设计的，在井眼倾角到达90度之后，井眼可能实际开始向上钻进。

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This paper has made a detailed introduction of adoption of the construction technology of upward vertical hole in the Heihe Dam, which presents a good example for drilling market.

本文详细介绍了黑河大坝倒垂孔的施工技术，对于开拓钻探市场提供了一个很好的范例。

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