| 摘要 |
Apparatus and methodology for reducing frictional forces on drilling apparatus when being progressed or retracted within a well bore. This is achieved through mechanical or hydraulic action on the drilling fluid to create a fluid pressure differential which is transmitted on to the drill string via pumps, causing the drill string to oscillate. The oscillation reduces the frictional interface between the drill string and the well bore, thus enabling increased depth or reach of the well bore.
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