| 摘要 |
A layer is taken off the borehole wall (3) over a set height, as the drilling head (5) is pulled, i.e. raised out. As in the case of downward drilling, the drilling fluid carries off the drillings (50) cut away from the wall. The height of this reverse cutting is limited. It extends from the given depth of drilling, over a given height only. The drilling head cuts away the layer. The drillings are removed, both during drilling and reverse cutting, by indirect hydraulic drilling. The drillings are sucked away immediately beneath the point of origin, during reverse cutting. On reaching the given depth of drilling, the drilling fluid in the borehole is replaced by solids-free water. An Independent claim is included for corresponding jet drilling equipment.
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