Remote actuation of downhole tools using fluid pressure from surface

Abstract

An apparatus for and a method of transmitting signals from the surface of a well to a location downhole in the well utilize a downhole fluid pressure sensor, a signal processing means located downhole in electrical connection with the pressure sensor and a downhole programmable logic unit capable of counting at least two signals received by the downhole pressure sensor. Typically, signals transmitted from the surface comprise a peak in pressure of downhole fluid located in production tubing run into a well bore and these signals are sensed by the downhole fluid pressure sensor. The logic unit outputs a signal to a tool to be actuated if it receives a number of signals within a particular time period, wherein the logic unit actuates the tool by the frequency of signals received rather than the amplitude of the signals received.

1 . An apparatus for transmitting signals from the surface of a well to a location downhole in the well, the apparatus comprising:
 a downhole fluid pressure sensor;   a signal processor located downhole in electrical connection with the pressure sensor; and   a downhole programmable logic unit capable of counting at least two signals received by the downhole pressure sensor.   
   
   
       2 . Apparatus as claimed in  claim 1 , wherein the programmable logic unit is capable of instructing actuation or operation of a tool based upon previously programmed logic. 
   
   
       3 . Apparatus as claimed in  claim 1 , wherein the signals transmitted from the surface comprise a peak in pressure of downhole fluid located in production tubing run into a well bore. 
   
   
       4 . Apparatus as claimed in  claim 1 , further comprising a mechanism to increase pressure of fluid at the surface such that the pressure is transmitted through the fluid to the downhole location. 
   
   
       5 . Apparatus as claimed in  claim 1 , wherein the signal processor comprises a filter to strip away the value of pressure sensed below a pre-determined filter level and furthermore the processor comprises a converter function to convert the value of pressure sensed from an analogue value into a digital value that can be input into the logic unit. 
   
   
       6 . Apparatus as claimed in  claim 1 , wherein the logic unit is adapted to output a signal to a tool to be actuated if it receives a number of signals within a particular time period, wherein the logic unit actuates the tool by the frequency of signals received rather than the amplitude of the signals received. 
   
   
       7 . Apparatus as claimed in  claim 1 , wherein the programmable logic unit is adapted to observe a peak in pressure and further comprises a timer adapted to monitor the time elapsed between a pair of peaks in pressure. 
   
   
       8 . Apparatus as claimed in  claim 1 , wherein the logic unit is adapted to output a signal to a tool to be actuated if it observes a particular number of signals received with each signal counting toward the total observed if it meets certain criteria. 
   
   
       9 . Apparatus as claimed in  claim 1 , wherein a peak in pressure is regarded as a positive value of change in pressure divided by change in time and if the actual pressure sensed is greater than a minimum value. 
   
   
       10 . Apparatus as claimed in  claim 9 , wherein the logic unit comprises a counter adapted to store a value, wherein the value stored is indicative of the number of positive peaks in pressure that are greater than a minimum value that have been observed wherein only separate peaks that occur within a particular time interval will count towards the said stored value. 
   
   
       11 . Apparatus as claimed in  claim 10 , wherein the counter is reset if the time since the last peak or the time between a pair of peaks is greater than a particular maximum time value wherein the said particular maximum time value is determined surface prior to running in to the well bore. 
   
   
       12 . Apparatus as claimed in  claim 10 , wherein the logic unit is further adapted to hold an actuation value, wherein the logic unit compares the counter value with the set actuation value and does not actuate the tool until the counter value matches the set actuation value at which point the logic unit instructs actuation of the tool. 
   
   
       13 . A method of transmitting signals from the surface of a well to a location downhole in the well, the method comprising:
 providing a downhole fluid sensor capable of sensing changes in downhole fluid and installing said sensor downhole;   providing a signal processor and installing said processor downhole in electrical connection with said sensor; and   providing a programmable logic unit capable of counting at least two signals received by the downhole sensor and installing said logic unit downhole in electrical connection with said signal processor.   
   
   
       14 . A method according to  claim 13 , wherein the downhole fluid sensor comprises a downhole fluid pressure sensor. 
   
   
       15 . A method according to  claim 13 , wherein the programmable logic unit is connected with a tool to be actuated and is capable of instructing actuation of the downhole tool based upon previously programmed logic. 
   
   
       16 . A method according to  claim 13 , wherein the signals transmitted from the surface comprise a peak in pressure of downhole fluid located in the well bore and the signals are sent from the surface of the well through the well bore fluid by increasing the pressure of the fluid at the surface such that the pressure is transmitted through the fluid to the downhole location where it is sensed by the downhole fluid sensor. 
   
   
       17 . A method according to  claim 16 , wherein the signal processor strips away the value of pressure sensed below a filter level. 
   
   
       18 . A method according to  claim 13 , wherein the signal processor converts the value of pressure sensed from an analogue value into a digital value that is input into the logic unit. 
   
   
       19 . A method according to  claim 13 , wherein the logic unit outputs a signal to the tool to be actuated if it receives a number of signals within a particular time period such that the logic unit is operated by the frequency of signals received. 
   
   
       20 . A method according to  claim 13 , wherein the programmable logic unit observes a peak in pressure and monitors the time elapsed between a pair of peaks in pressure. 
   
   
       21 . A method according to  claim 13 , wherein the logic unit outputs a signal to a tool to be actuated if it observes a particular number of signals received with each signal counting toward the total observed if it meets certain criteria. 
   
   
       22 . A method according to  claim 13 , wherein a peak in pressure is regarded as a positive value of change in pressure divided by change in time if the actual pressure sensed is greater than a minimum value. 
   
   
       23 . A method according to  claim 13 , wherein the logic unit stores a value indicative of the number of positive peaks in pressure that are greater than a minimum value that have been observed wherein only separate peaks that occur within a particular time interval will count towards the said stored value. 
   
   
       24 . A method according to  claim 23 , wherein the count is reset if the time since the last peak or the time between a pair of peaks is greater than a particular maximum time value wherein the said particular maximum time value is determined prior to running in to the well bore. 
   
   
       25 . A method according to  claim 23 , wherein the logic unit holds an actuation value and the logic unit compares the counted value with the held actuation value and does not actuate the tool until the counted value matches the held actuation value.