Steering System for Drill String

• US 20160002978A1
• Filed: 05/11/2015
• Published: 01/07/2016
• Est. Priority Date: 07/07/2014
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Rushton, Guy James
• Granted Patent: US 9,869,140 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: E21B 17/1014 Flexible or expansible centering means, e.g. with pistons pressing against the wall of the well E21B17/1042 takes precedence
• CPC Class Codes: E21B 7/06 Deflecting the direction of boreholes

Abstract

A technique facilitates directional drilling of boreholes. A steerable system has a plurality of actuator pistons slidably mounted in a mechanical structure. The mechanical structure comprises a radially inward portion containing ports to deliver a portion of drilling mud to the plurality of actuator pistons. The mechanical structure also has a radially outward portion positioned to define a main flow passage extending longitudinally through the steerable system between the radially inward portion and the radially outward portion of the mechanical structure.

Claims

1. A system for forming a directional borehole, comprising:

a rotary steerable system having a plurality of actuator pistons slidably mounted in a mechanical structure, the mechanical structure comprising;

a radially inward portion containing ports to deliver actuating mud to the plurality of actuator pistons;

a radially outward portion; and

a piston chamber portion extending radially between the radially inward portion and the radially outward portion, mechanical structure defining a main flow passage extending longitudinally through the rotary steerable system between the radially inward portion and the radially outward portion for directing a flow of actuating mud to a drill bit.

2. The system as recited in claim 1, further comprising a valve system positioned radially inward of the main flow passage.

3. The system as recited in claim 1, wherein the actuator pistons act against corresponding steering pads.

4. The system as recited in claim 1, wherein the actuator pistons have circular cross-sections.

5. The system as recited in claim 1, wherein the actuator pistons have non-circular cross-sections.

6. The system as recited in claim 1, wherein the rotary steerable system is connected into a drill string.

7. The system as recited in claim 1, wherein the plurality of actuator pistons comprises three actuator pistons.

8. The system as recited in claim 1, wherein at least a portion of each actuator piston reciprocates to a position radially inward of the main flow passage.

9. The system as recited in claim 3, wherein the rotary steerable system further comprises cam followers located between the actuator pistons and the corresponding steering pads.

10. A method, comprising:

positioning a rotary steerable system in a drill string;

routing drilling mud through the drill string;

using the drilling mud to operate actuator pistons of the rotary steerable system via valve controlled ports located at a radially inward position within the rotary steerable system; and

directing a remainder of the drilling mud past the rotary steerable system via a main flow passage located radially outward of the valve controlled ports.

11. The method as recited in claim 10, further comprising locating the valve controlled ports and a corresponding valve system in a radially inward portion of a mechanical structure.

12. The method as recited in claim 11, further comprising mounting the actuator pistons in corresponding piston passages oriented radially in the mechanical structure.

13. The method as recited in claim 12, further comprising actuating the actuator pistons to selectively move a plurality of corresponding steering pads.

14. The method as recited in claim 13, further comprising using cam followers between the actuator pistons and the corresponding steering pads.

15. The method as recited in claim 13, further comprising pivotably coupling each corresponding steering pad to a mechanical structure of the rotary steerable system.

16. The method as recited in claim 10, wherein using comprises reciprocating the actuator pistons such that a portion of each actuator piston moves to a position radially inward of the main flow passage.

17. A system for steering during drilling, comprising:

a drill string having a rotary steerable system, the drill string being constructed to enable a flow of drilling mud therethrough, the rotary steerable system comprising;

a plurality of actuator pistons operated by the flow of drilling mud;

a plurality of ports located at a radially inward position within the rotary steerable system, the ports of the plurality of ports being positioned to direct flow of the drilling mud to corresponding actuator pistons of the plurality of actuator pistons; and

a mechanical structure having a main flow passage located radially outward of the plurality of ports, the main flow passage directing a remainder of the drilling mud past the rotary steerable system.

18. The system as recited in claim 17, wherein the rotary steerable system further comprises a corresponding valve system to control flow of the drilling mud to selected ports of the plurality of ports, the plurality of ports and the corresponding valve system being located in a radially inward portion of the mechanical structure.

19. The system as recited in claim 18, wherein the actuator pistons move within corresponding piston passages oriented radially in the mechanical structure.

20. The system as recited in claim 19, wherein the rotary steerable system further comprises a plurality of corresponding steering pads, the actuator pistons being actuated to move selected, corresponding steering pads.