Downlinking Communication System and Method Using Signal Transition Detection

• US 20110286309A1
• Filed: 08/04/2011
• Published: 11/24/2011
• Est. Priority Date: 05/24/2010
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Smith International Incorporated (Schlumberger NV)
• Inventors: Sugiura, Junichi
• Granted Patent: US 8,792,304 B2
• Time in Patent Office: Days
• US Class Current: 367/83
• CPC Class Codes: E21B 47/18 through the well fluid , e.g. mud pressure pulse telemetry

Abstract

A downlinking signal is transmitted downhole from the surface using drilling fluid as the communications medium. The downlinking signal includes at least a synchronization phase and a command phase. The downlinking signal is differentiated upon reception such that attributes of the synchronization phase may be used to determine corresponding attributes of the command phase. Commands may be transmitted downhole while drilling and simultaneously while using mud-pulse telemetry uplinking techniques.

Claims

10-1. The method of claim 1, wherein (a) further comprises rotary drilling the borehole.

14. A system for communicating at least one command from a surface location to a bottom hole assembly located in a borehole, the system comprising:

a pump for pumping drilling fluid from the surface through a drill string to the bottom hole assembly;

a flow control apparatus for controlling a flow rate of the drilling fluid, the flow rate encoding a downlinking signal, the downlinking signal including at least a synchronization phase and a command phase, each of the synchronization phase and the command phase including at least one distinct flow rate pulse;

a downhole detector configured to detect the downlinking signal; and

a downhole controlled configured to decode the downlinking signal, the controller configured to (i) differentiate the downlinking signal, (ii) decode the synchronization phase to determine at least one of a bit length and a duration of the command phase and (iii) decode the command phase to determine the command.

15. The system of claim 14, wherein the flow control apparatus is computer controlled.

16. The system of claim 14, wherein the flow control apparatus is configured to selectively open and close a bypass valve, wherein opening the bypass valve reduces the flow rate in the drill string.

17. The system of claim 14, wherein the flow control apparatus is configured to control the rotation rate of the pump.

18. The system of claim 14, wherein the detector comprises a differential transducer configured to measure a pressure differential between drilling fluid in the drill string and drilling fluid in a borehole annulus.

19. The system of claim 14, wherein the controller is configured to compute at least one of the bit length and the duration from a time difference between first and second zero-crossings in said differentiated downlinking signal.

20. The system of claim 14, wherein the controller is configured to determine the command from at least one time difference between first and second zero-crossings in said differentiated downlinking signal.

21. The system of claim 14, further comprising a rotary steerable tool configured to execute the command, the rotary steerable tool including a plurality of extendable and retractable blades, the blades being operative to control a direction of drilling of the borehole, execution of the command causing extension or retraction of at least one of the blades, the command being selected from the group consisting of absolute offset, absolute percentage force, absolute toolface angle, absolute target inclination, absolute target azimuth, absolute dogleg severity, change in offset, change in percentage force, change in toolface angle, change in inclination, change in azimuth, and change in dogleg severity.