Patent ID: 7413034

Claim:
A steering tool for use in drilling a borehole, comprising: (a) a tubular housing, the housing having an interior, an exterior, and defining a housing bore; (b) a tool actuating device movably supported within the interior of the housing, the tool actuating device being capable of an actuating movement relative to the housing; (c) a plurality of hydraulically actuated steering devices circumferentially spaced about the exterior of the housing, the steering devices being independently actuatable between a retracted position and an extended position as a result of the actuating movement of the tool actuating device; (d) a hydraulic control system contained within the interior of the housing and operably interposed between the tool actuating device and the steering devices, for converting the actuating movement of the tool actuating device to independent actuation of the steering devices between the retracted position and the extended position; and (e) a hydraulic fluid for use in the hydraulic control system in order to actuate the steering devices, wherein the hydraulic fluid is isolated from other fluids.