Wireless telemetry systems for downhole tools

Abstract

Apparatus and method for transmitting data in a borehole ( 10 ) between a downhole installation including one or more tools ( 20 ) (for example downhole testing tools) and a surface installation ( 62 ), wherein the downhole installation is connected to the surface installation by means of a tubular conduit (such as a drill string or production tubing 14 )). The apparatus comprises: an acoustic modem ( 26 ) associated with each tool, the modem acting to convert tool signals such as electrical tool signals into acoustic signals; and a hub ( 90 ) forming part of the downhole installation to which the tools and tubular conduit are connected and comprising an acoustic receiver ( 74 ) and an electromagnetic transmitter ( 80 ). The acoustic modems operate to generate acoustic signals in the downhole installation representative of the tool signals, the acoustic signals passing along the downhole installation to be received at the acoustic receiver of the hub, the received acoustic signals being used to operate the electromagnetic transmitter to transmit electromagnetic signals to the surface for reception at the surface installation.

1 . Apparatus for transmitting data in a borehole between a downhole installation including one or more tools and a surface installation, wherein the downhole installation is connected to the surface installation by means of a tubular conduit, the apparatus comprising:
 an acoustic modem associated with each tool, the modem acting to convert electrical tool signals into acoustic signals; and   a hub forming part of the downhole installation to which the tools and tubular conduit are connected and comprising an acoustic receiver and an electromagnetic transmitter;   wherein the acoustic modems operate to generate acoustic signals in the downhole installation representative of the electrical tool signals, the acoustic signals passing along the downhole installation to be received at the acoustic receiver of the hub, the received acoustic signals being used to operate the electromagnetic transmitter to transmit electromagnetic signals to the surface for reception at the surface installation.   
     
     
         2 . Apparatus as claimed in  claim 1 , wherein the hub further comprises an acoustic transmitter which is operable to transmit the acoustic signals received by the hub to the surface installation via the tubular conduit. 
     
     
         3 . Apparatus as claimed in  claim 2 , further comprising one or more acoustic repeaters disposed along the tubular conduit and operable to retransmit the acoustic signal received from the hub. 
     
     
         4 . Apparatus as claimed in  claim 1 , wherein at least one tool is located below the hub. 
     
     
         5 . Apparatus as claimed in  claim 1 , wherein at least one tool is located above the hub. 
     
     
         6 . Apparatus as claimed in  claim 1 , wherein the downhole installation comprises at least one packer to isolate a zone of the borehole below the hub. 
     
     
         7 . Apparatus as claimed in  claim 6 , comprising multiple packers arranged to isolate multiple zones of the well below the hub. 
     
     
         8 . Apparatus as claimed in  claim 7 , wherein the downhole installation comprises separate tools in each zone. 
     
     
         9 . Apparatus as claimed in  claim 1 , wherein the hub further comprises an electromagnetic receiver for receiving electromagnetic signals from the surface installation, and an acoustic transmitter for transmitting acoustic signals derived from the received electromagnetic signals. 
     
     
         10 . A method of communicating between one or more tools comprising a downhole installation and a surface installation, wherein the downhole installation and surface installation are connected by means of a tubular conduit, the method comprising:
 using electrical signal produced by the tools to generate acoustic signals which pass along the downhole installation to a hub;   receiving the acoustic signals at the hub; and   using the received acoustic signals to generate electromagnetic signals that pass from the hub to the surface location.   
     
     
         11 . A method as claimed in  claim 10 , further comprising generating acoustic signals at the hub which pass along the tubular conduit to the surface installation. 
     
     
         12 . A method as claimed in  claim 11 , further comprising receiving the acoustic signals and retransmitting them at multiple locations along the tubular conduit. 
     
     
         13 . A method as claimed in  claim 10 , further comprising transmitting electromagnetic signals from the surface installation to the hub and converting these signals into acoustic signals for transmission to the tools in the installation. 
     
     
         14 . A method of testing a well, comprising:
 locating testing tools in a borehole in a number of zones to be tested;   isolating the zones from each other and the rest of the well;   operating the testing tools in each zone; and   transmitting data from the testing tools in each zone to a surface installation by means of a method according to any of  claims 10 .