Apparatus and methods for improved cement plug placement

Abstract

A method and apparatus for making real-time measurements of downhole properties during cement plug placement. A wired placement conduit ( 30 ) is lowered downhole releasing a sensor package ( 34 ). The sensor package is capable of measuring downhole properties in real-time in the period while cement plug sets.

1 . Apparatus for placing a cement plug in a well, comprising:
 a pipe for delivering a cement slurry to a predetermined location in the well to be plugged;   at least one sensor located at a lower end of the pipe and operable to measure parameters in the well at the predetermined location; and   an operating system located at the surface for receiving output signals from the sensor;   wherein the sensor is configured to measure at least one parameter relevant to cement plug placement and is connected to the operating system by means of a cable.   
       wherein the sensor performs a caliper measurement for indicating hole diameter as the pipe is run into the well. 
     
     
         2 . Apparatus as claimed in  claim 1 , wherein the sensor comprises a differential pressure sensor. 
     
     
         3 . Apparatus as claimed in  claim 1 , wherein the sensor comprises a temperature sensor. 
     
     
         4 . A method of placing a cement plug in a well, comprising:
 providing a pipe for delivery of the cement plug with a sensor at its end;   introducing the pipe into the well such that its end is at a predetermined location for placement of the plug;   operating the sensor to measure at least one parameter relevant to cement plug placement to measure parameters in the well at the predetermined location; and   sending output signals from the sensor to an operating system located at the surface by means of a cable.   
       wherein the step of operating the sensor comprises making a caliper measurement of the well, at least in the region of the predetermined location, to determine the diameter of the well. 
     
     
         5 . A method as claimed in  claim 4  wherein the step of operating the sensor further comprises obtaining a differential pressure measurement in the fluids in the well in region of predetermined location. 
     
     
         6 . A method as claimed in  claim 4 , wherein the step of operating the sensor further comprises making a temperature measurement. 
     
     
         7 . (canceled) 
     
     
         8 . A method for real-time measurements of the properties of a wellbore during cement plug placement comprising:
 providing a pipe for delivery of the cement plug with a sensor at its end;   introducing the pipe into the well such that its end is at a predetermined location for placement of the plug;   operating the sensor to measure at least one parameter relevant to cement plug placement to measure parameters in the well at the predetermined location; and   sending output signals from the sensor to an operating system located at the surface by means of a cable.   
       wherein the step of operating the sensor comprises making a caliper measurement of the well, at least in the region of the predetermined location, to determine the diameter of the well. 
     
     
         9 . The method of  claim 8 , wherein the step of operating the sensor further comprises obtaining a differential pressure measurement in the fluids in the well in region of predetermined location. 
     
     
         10 . The method of  claim 8 , wherein the step of operating the sensor further comprises making a temperature measurement. 
     
     
         11 . The method of  claim 8 , wherein the calliper measurement is performed as the pipe is run into the well. 
     
     
         12 . The apparatus of  claim 2  further comprising a sensor for temperature measurement. 
     
     
         13 . The apparatus of  claim 1 , wherein the sensor is detachable from the pipe. 
     
     
         14 . The apparatus of  claim 12 , wherein the caliper, the differential pressure sensor and the temperature sensor are part of a sensor package that is detachable from the pipe so as to remain at the predetermined location in the well and houses a sensor cable which can be withdrawn to connect the sensor to the operating system at the surface. 
     
     
         15 . The method of  claim 5  further comprising making a temperature measurement. 
     
     
         16 . The method of  claim 9  further comprising making a temperature measurement. 
     
     
         17 . The method of  claim 15 , wherein all the measurements are made by sensors located in a sensor package that is detachable from the pipe so as to remain at the predetermined location in the well and houses a sensor cable which can be withdrawn to connect the sensor to the operating system at the surface. 
     
     
         18 . The method of  claim 16 , wherein, all the measurements are made by sensors located in a sensor package that is detachable from the pipe so as to remain at the predetermined location in the well and houses a sensor cable which can be withdrawn to connect the sensor to the operating system at the surface. 
     
     
         19 . The method of  claim 17 , wherein the sensor cable is connected to the pipe such that withdrawal of the pipe from the well causes the sensor cable to be withdrawn from the sensor package. 
     
     
         20 . The method of  claim 17 , wherein the sensor cable is be connected to a cable extending along the pipe to the operating system at the surface. 
     
     
         21 . The method of  claim 4 , wherein the cement plug is made from Portland cement, magnesium oxychloride cement, epoxy resins, or geopolymers, and mixtures thereof.