| 摘要 |
A rotatable steerable drill string in which guidance module controls the direction of the drilling. A magnetorheological fluid in the module supplies pressure to pistons that apply forces to the wall of the bore and thereby alter the direction of the drilling. The pressure applied by the magnetorheological fluid is regulated by valves that apply a magnetic field to the fluid so as to increase its fluid shear strength thereby controlling the actuation of the pistons and the direction of the drilling.
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