Patent ID: 6942044

Claim:
A three-dimensional steering tool for use in drilling a borehole in an underground formation in which an elongated conduit extends from the surface through the borehole and in which the steering tool is mounted on the conduit near a drill bit for drilling the borehole, the steering tool comprising an integrated telemetry section, rotary section and flex section aligned axially along the steering tool for separately controlling inclination and azimuth angles at the drill bit; in which the flex section includes an elongated drive shaft coupled to the drill bit and adapted to be rotatably driven for rotating the drill bit, the drive shaft being bendable laterally to define a deflection angle thereof, and a deflection actuator coupled to the drive shaft, the deflection actuator comprising a deflection housing surrounding the drive shaft and having a longitudinal axis and an elongated deflection piston movable in the deflection housing for applying a lateral bending force to the drive shaft for making changes in the deflection angle of the drive shaft and which is transmitted to the drill bit as an inclination angle steering adjustment; in which the rotary section is coupled to the actuator and includes a rotator actuator for transmitting a rotational force to the deflection actuator to rotate the deflection piston to thereby change the rotational angle at which the lateral bending force is applied to the drive shaft which is transmitted to the drill bit as an azimuth angle steering adjustment; and in which the telemetry section measures the inclination angle and the azimuth angle during drilling and compares them with desired inclination and azimuth angle information to produce inclination control signals for operating-the deflection actuator to make steering adjustments in the inclination angle and for separately producing azimuth control signals for operating the rotator actuator for making steering adjustments in the azimuth angle.