| 摘要 |
The present invention relates to drilling apparatus comprising a drill-bi t (1) capable of rotary and high frequency oscillatory loading; and control means for controlling applied rotational and/or oscillatory loading of the d rill-bit, the control means having adjustment means for varying the applied rotational and/or oscillatory loading, said adjustment means being responsiv e to conditions of the material through which the drill is passing. The cont rol means is in use provided on the apparatus in a downhole location and inc ludes sensors for taking downhole measurements of material characteristics, whereby the apparatus is operable downhole under closed loop real-time contr ol. The apparatus can determine appropriate loading parameters for the drill -bit in order to achieve and maintain resonance between the drill-bit and th e drilled material in contact therewith.
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