Downhole Steering System

摘要

A technique facilitates drilling of deviated boreholes. The technique employs a drilling system which may be disposed along a drill string. The drilling system may be used to drill a straight section of a borehole along a straight borehole axis and to also selectively drill a deviated section of the borehole. The drilling system comprises a housing, a bit shaft rotatably mounted in the housing, and an actuator which may be selectively actuated to shift the bit shaft to another position with respect to the straight borehole axis. The actuator is selectively shiftable between an unbiased mode and a biased mode. In the unbiased mode, the bit shaft axis is in a first position with respect to the straight borehole axis during drilling of the straight section of borehole. The actuator may be selectively shifted to the biased mode in which the bit shaft axis is shifted off axis relative to the straight borehole axis to enable drilling of the desired deviated section of the borehole.

主权项

1. A system for steering during drilling, comprising:
a drill string having a drilling system able to drill a straight section of a borehole along a straight borehole axis and able to drill a deviated section of the borehole, the drilling system comprising:
a bearing housing;a bit shaft rotatably mounted in the bearing housing and having a bit shaft axis; andan actuator selectively shiftable between an unbiased mode in which the bit shaft axis is sufficiently aligned with the straight borehole axis to enable drilling of a straight section of the borehole and a biased mode in which the bit shaft axis is shifted off axis relative to the straight borehole axis to enable deviated drilling while the drill string is rotationally stationary.