Fiberoptic systems and methods for acoustic telemetry

Abstract

A disclosed acoustic telemetry system includes a downhole acoustic telemetry module that generates an acoustic uplink signal such as a pulsed fluid flow or compressional waves in a tubing string wall. An optical waveguide transports an optical signal representing the acoustic uplink signal to the surface interface. A related telemetry method includes acquiring measurements downhole, transmitting the measurements in the form of an acoustic signal, and sensing the acoustic signal via an optical waveguide.

What is claimed is: 
     
         1 . A downhole telemetry method that comprises:
 acquiring measurements downhole;   transmitting downhole measurements in the form of an acoustic signal; and   sensing the acoustic signal downhole via an optical waveguide.   
     
     
         2 . The method of  claim 1 , wherein the optical waveguide comprises an optical fiber and said sensing comprises distributed acoustic sensing along said optical fiber. 
     
     
         3 . The method of  claim 1 , wherein the optical waveguide comprises an optical fiber and said sensing includes transducing motion or pressure associated with the acoustic signal into applied stress or deformation of the optical fiber to modulate passing light. 
     
     
         4 . The method of  claim 1 , wherein said sending includes converting motion or pressure associated with the acoustic signal into a modulated optical signal for transmission via the optical waveguide. 
     
     
         5 . The method of  claim 4 , wherein said converting includes modulating an optical signal received via said optical waveguide. 
     
     
         6 . The method of  claim 4 , wherein said converting includes obtaining an electrical response to said motion or pressure and applying the electrical response to a downhole light emitter that transmits said modulated optical signal. 
     
     
         7 . The method of  claim 4 , wherein said converting includes obtaining an electrical response to said motion or pressure and applying the electrical response to a transducer that deforms or applies stress to the optical fiber to modulate passing light. 
     
     
         8 . The method of  claim 1 , further comprising:
 transmitting one or more commands via the optical waveguide to a downhole transducer; and   generating an acoustic downlink signal representing said one or more commands.   
     
     
         9 . An acoustic telemetry system that comprises:
 a downhole acoustic telemetry module that generates an acoustic uplink signal; and   an optical waveguide that transports an optical signal representing the acoustic uplink signal to a surface interface.   
     
     
         10 . The system of  claim 9 , further comprising one or more downhole sensors coupled to the optical waveguide, wherein the one or more sensors convert the acoustic uplink signal into said optical signal. 
     
     
         11 . The system of  claim 9 , wherein the optical waveguide comprises an optical fiber that converts the acoustic signal into modulation of light provided by distributed acoustic sensing electronics coupled to the surface interface. 
     
     
         12 . The system of  claim 9 , wherein the acoustic signal comprises modulation of a fluid flow. 
     
     
         13 . The system of  claim 12 , wherein the fluid flow comprises a circulated fluid. 
     
     
         14 . The system of  claim 12 , wherein the fluid flow comprises a produced fluid. 
     
     
         15 . The system of  claim 9 , wherein the acoustic signal comprises at least one of compressional, shear, or torsional waves in a tubing string wall. 
     
     
         16 . The system of  claim 15 , wherein the tubing string comprises coiled tubing. 
     
     
         17 . The system of  claim 15 , wherein the tubing string comprises production tubing or a casing string. 
     
     
         18 . The system of  claim 9 , further comprising a downhole optical-to-acoustic transducer that converts an optical downlink signal into an acoustic downlink signal. 
     
     
         19 . The system of  claim 18 , wherein the optical waveguide also transports the optical downlink signal from the surface interface to the downhole transducer.