Patent ID: 7631707

Claim:
A rotary steerable drilling apparatus for drilling a wellbore, comprising: a shaft adapted for joining to a drill string; a sleeve concentric with the shaft, the shaft being free to rotate within the sleeve; a plurality of individually operable actuator modules fixed to the sleeve, each of the actuator modules includes a guide and a movable guide rail, and a wire wound about the guide and the movable guide rail, the wire being formed of a shape memory alloy such that a change in temperature of the alloy within a selected range of temperature causes the alloy to change from a first dimension to a second dimension; a plurality of pads in proximity to the actuator modules and adapted to apply a force to a selected wall of the wellbore in response to the change of the alloy from the first to the second dimension, the shape memory alloy being mechanically linked to the pads to exert an outward force on the pads when the shape memory alloy is actuated.