| 摘要 |
A deflection control sub to be used with or as part of a down hole drilling motor, is a drill string element consisting of an upper and a lower portion connected by bearings for relative rotation about an axis that is not parallel to the axes of the two portions. When assembled ,and in the straight configuration the bearing axis has about a two degree angle relative to the other two axes. When one portion is rotated relative to the other one half turn, the axes of opposite ends of the sub are deflected about four degrees. The actual amount is a designers choice, and deflects the axis of an associated drill string that amount within the sub. The sub portions are rotated relative to each other by a drilling fluid powered motor in response to drilling fluid pressure difference between a fluid channel extending through the sub and the annulus outside the sub. A spring biases the opposite ends to rotate to the straight configuration until the motor overcomes the spring to deflect the axis. Options include two forms of deflection motor disablers which respond to different mud flow rate controls. A further option includes a signal valve operated by the moving motor to briefly produce a pressure pulse detectable at the surface to indicate that the sub is changing configuration.
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