Downhole wireline communication

Abstract

Disclosed is a method for downhole data communication in a downhole communications system. The method is performed by a communication equipment configured to be arranged to transmit and receive signals via an associated wireline at a bitrate. The method comprises the steps of, determining, at one or more frequencies, one or more characteristics of the wireline associated with each of the one or more frequencies, and adjusting the bitrate based on the determined one or more characteristics. Also, a downhole data communications system, comprising at least one communication equipment configured to perform the method is presented. Further to this, a communication equipment configured to be arranged to perform the method is disclosed.

1 . A method for downhole data communication in a downhole communications system performed by a communication equipment configured to be arranged to transmit and receive signals via an associated wireline at a bitrate, the method comprising:
 determining, at one or more frequencies, one or more characteristics of the wireline associated with each of the one or more frequencies,   estimating, from the one or more characteristics, a wireline frequency response function associated with each of the one or more frequencies, and wherein the step of adjusting the bitrate is further based on the estimated wireline frequency response function, and   adjusting the bitrate based on the determined one or more characteristics, wherein the step of adjusting comprises comparing the estimated wireline frequency response function with a first threshold and a second threshold and if the estimated wireline frequency response function is:   above the first threshold, increase the bitrate,   below the second threshold, decrease the bitrate, and   wherein the step of adjusting comprises comparing at least one of the values of the estimated wireline frequency response function with a third threshold and for each value below the third threshold, bar a frequency being associated with such value from use.   
     
     
         2 . The method according to  claim 1 , wherein the one or more characteristics of the wireline comprises a loss characteristic. 
     
     
         3 . The method according to  claim 1 , wherein the step of determining comprises transmitting and/or receiving at least one single tone characterisation signal. 
     
     
         4 . The method according to  claim 3 , wherein more than one single tone characterisation signal is sent, each single tone characterisation signal having different frequency and/or amplitude. 
     
     
         5 . The method according to  claim 1 , wherein the step of determining comprises receiving one or more single tone characterisation signals and the step of estimating comprises comparing the one or more received single tone characterization signals to a reference characterisation signal. 
     
     
         6 . The method according to  claim 3 , wherein the one or more single tone characterisation signals are more than one single tone characterisation signal and the single tone characterisation signal spaced in frequency between 1 Hz and 10 Mhz, preferably between 10 Hz and 1 MHz. 
     
     
         7 . The method according to  claim 1 , further comprising, after the step of estimating, a step of shaping the signal, wherein the step of shaping comprises calculating and applying one or more shaping parameters. 
     
     
         8 . The method according to  claim 1 , wherein the method is initiated by the detection a characterisation trigger. 
     
     
         9 . The method according to  claim 8 , wherein the characterisation trigger comprises the detection of start-up of the wireline transceiver. 
     
     
         10 . The method according to  claim 8 , wherein the characterisation trigger comprises detecting a change in one or more environmental parameters. 
     
     
         11 . The method according to  claim 10 , wherein the one or more environmental parameters comprise(s) any or all of temperature, acidic concentration, air pressure, humidity and cable changes. 
     
     
         12 . A downhole data communications system, comprising at least one communication equipment configured to perform the method according to  claim 1 . 
     
     
         13 . A communication equipment configured to be arranged to perform the method according to  claim 1 .