System and method for transmission of pulses

Abstract

A method and a system for monitoring one or more control parameters in a borehole, wherein a downhole tool is mounted in a drill string and is able to measure at least one control parameter using suitable sensor units is provided. The downhole tool generates at least one pulsating signal based on the measurements, wherein this pulsating signal includes a single pulse where the pulse length is determined as function of the value of the measured control parameter. The pulse length may further be determined using a selected resolution for that control parameter. The pulsating signal is then transmitted to ground level via the drilling fluid where it can be read by simply monitoring the pump pressure. A simple test can be performed before starting the operation of the drill string.

1 - 11 . (canceled) 
     
     
         12 . A method for monitoring one or more control parameters in a borehole, comprising the following steps:
 operating a drill string with at least one downhole tool in the borehole,   detecting an event,   measuring at least a first control parameter,   generating at least one pulsating signal via the at least one downhole tool, the at least one pulsating signal comprising a value of the first control parameter,   transmitting the at least one pulsating signal to a ground level,   
       wherein 
       the method further comprises the steps of:
 measuring at least a second control parameter, 
 generating at least a second pulsating signal via the at least one downhole tool, the second pulsating signal comprises a value of the second control parameter, 
 transmitting the second pulsating signal to the ground level, and wherein each of the first and second pulsating signals comprises a single pulse having a pulse length and a predetermined pulse amplitude, wherein the pulse length of the first pulsating signal is determined as a function of the value of the first control parameter, and the pulse length of the second pulsating signal is determined as a function of the value of the second control parameter, and wherein each of said single pulses comprises a first pulse section having a constant pulse length of more than 0 seconds and up to 20 seconds and a second pulse section having a variable pulse length, wherein the variable pulse length of the single pulse of the first pulsating signal is determined as a function of the value of the first control parameter, and the variable pulse length of the single pulse of the second pulsating signal is determined as a function of the value of the second control parameter. 
 
     
     
         13 . A method according to  claim 12 , wherein the pulsating signals have a predetermined resolution which is determined based on a maximum value of said first or second control parameter, respectively, and wherein said pulse length or variable pulse length is determined based on said predetermined resolution. 
     
     
         14 . A method according to  claim 12 , wherein the step of generating at least two pulsating signals each comprises generating positive and/or negative pulsating signals relative to a reference amplitude. 
     
     
         15 . A method according to  claim 12 , wherein the method further comprises the steps of:
 prior to operating the drill string, performing a test of the at least one downhole tool by:
 pumping a drilling fluid into the drill string via a pump system, 
 monitoring the pressure of the drilling fluid within a predetermined time window, 
 stopping the pump system, 
 measuring at least one of the first control parameter and the second control parameter, and 
 restarting the pump system so that pumping of the drilling fluid is resumed. 
   
     
     
         16 . A method according to  claim 12 , wherein the method further comprises the step of activating the at least one downhole tool when a predetermined event is detected. 
     
     
         17 . A method according to  claim 12 , wherein the parameters detected by the first and second sensors are the inclination angle and the azimuth angle. 
     
     
         18 . A system for monitoring two or more control parameters in a borehole, comprising:
 a drill string with at least one downhole tool,   an operating system located at a ground level, wherein the operating system is configured to operate the drill string in the borehole,   the at least one downhole tool comprises at least a first sensor unit configured to measure at least a first control parameter and a control unit configured to detect an event, the at least one downhole tool further comprises a pulse generating unit configured to generate at least one pulsating signal and to transmit said at least one pulsating signal to the ground level, wherein the at least one pulsating signal comprises a value of the first control parameter,   
       wherein the at least one downhole tool further comprises at least a second sensor unit configured to measure at least a second control parameter, wherein the pulse generating unit is further configured to generate at least a second pulsating signal and to transmit said second pulsating signal to the ground level, wherein the second pulsating signal comprises a value of the second control parameter and wherein each of the pulsating signals comprises a single pulse having a pulse length and a predetermined pulse amplitude, wherein the pulse generating unit is further configured to determine the pulse length of the single pulse of the first pulsating signal as a function of the value of the first control parameter, and the pulse generating unit is further configured to determine the pulse length of the single pulse of the second pulsating signal as a function of the value of the second control parameter, and wherein each of the first and second single pulses comprises a first pulse section having a constant pulse length of more than 0 seconds and up to 20 seconds and a second pulse section having a variable pulse length, and wherein the variable pulse length of the single pulse of the first pulsating signal is determined as function of the value of the first control parameter and the variable pulse length of the single pulse of the second pulsating signal is determined as function of the value of the second control parameter. 
     
     
         19 . A system according to  claim 18 , wherein the at least one downhole tool further comprises an activation unit configured to activate the downhole tool when a predetermined event is detected. 
     
     
         20 . A system according to  claim 18 , wherein the control unit is further configured to detect said event by monitoring an operating parameter. 
     
     
         21 . A system according to  claim 18 , wherein the at least one downhole tool further comprises at least one memory unit configured to store measurements of at least one of the first control parameter and the second control parameter.