| 摘要 |
A method of conducting borehole operations using a downhole tool positioned in borehole by means of an elongate tubular drill string comprises imposing a torsional vibration upon the tubing string at a frequency of less than about 5 Hz. The vibration may be controlled to a predetermined length of the string, or may encompass its entire length. The operation may be a drilling operation, and the downhole tool a drilling assembly. The string may comprise a coiled tubing. A suitable vibrator may comprise a high torque, low speed electric motor located at the same end of the tubing as the drilling assembly. The vibration may be monitored and a feedback signal produced to be used in controlling the vibration frequency. The vibrations will reduce the amount of friction between the tubing and the walls of the borehole.
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