Method and apparatus for measuring deformation of elastomeric materials

Abstract

A method for measuring the deformation of elastomeric materials using acoustic signals involves obtaining a sample, positioning the sample in a sealable chamber, sealing the chamber, and setting a temperature and pressure inside the chamber. A test fluid may be introduced to the chamber. An acoustic signal is used to measure a characteristic of the sample, such as a dimension or a modulus. Repeated measurements may be made overtime to monitor changes in the sample in response to temperature and pressure. The acoustic signal may be generated by an acoustic transducer including a backing component including a fluorine-containing polymer in which metal particles are incorporated. The sample may be a non-metallic material. Conditions inside the chamber may be set to simulate a wellbore environment.

1 . A method of measuring deformation of a non-metallic material, comprising:
 placing a sample of a non-metallic material in a sealable chamber;   sealing the sealable chamber;   generating an acoustic signal;   bringing the sealable chamber to a test pressure;   bringing the sealable chamber to a test temperature;   supplying a test medium to the sealable chamber; and   measuring a characteristic of the sample using the acoustic signal.   
     
     
         2 . The method of  claim 1 , wherein the test medium is a hydrocarbon fluid. 
     
     
         3 . The method of  claim 1 , wherein the characteristic is a modulus of the sample. 
     
     
         4 . The method of  claim 1 , wherein the acoustic signal is generated by an acoustic transducer. 
     
     
         5 . The method of  claim 4 , wherein the acoustic transducer comprises:
 a piezoelectric element configured to generate acoustic signals according to an electrical signal that is applied to the piezoelectric element;   a backing component contacting a back-side surface of the piezoelectric element; and   an encasing material that surrounds the piezoelectric element and the backing component,   wherein the backing component comprises a fluorine-containing polymer in which metal particles are incorporated, and   the metal particles comprise greater than 60% of the backing component by volume.   
     
     
         6 . The method of  claim 4 , further comprising positioning an acoustic reflecting plate between the acoustic transducer and the sample such that only a first portion of the acoustic signal generated by the transducer reaches the sample and a second portion of the acoustic signal generated by the transducer is reflected back to the acoustic transducer by the acoustic reflecting plate. 
     
     
         7 . An apparatus for measuring deformation of a non-metallic material, comprising:
 a sealable chamber;   a sample holder for holding a sample of a non-metallic material inside the sealable chamber;   a port for introducing a test medium; and   an acoustic transducer positioned to supply an acoustic signal to the sample.   
     
     
         8 . The apparatus of  claim 7 , wherein a temperature and a pressure inside of the sealable chamber can be controlled. 
     
     
         9 . The apparatus of  claim 7 , wherein the acoustic transducer comprises:
 a piezoelectric element configured to generate acoustic signals according to an electrical signal that is applied to the piezoelectric element;   a backing component contacting a back-side surface of the piezoelectric element; and   an encasing material that surrounds the piezoelectric element and the backing component,   wherein the backing component comprises a fluorine-containing polymer in which metal particles are incorporated, and   the metal particles comprise greater than 60% of the backing component by volume.   
     
     
         10 . The apparatus of  claim 9 , wherein the fluorine-containing polymer is a fluoroelastomer that comprises a di-polymer of vinylidene fluoride and hexafluoropropylene having a Mooney viscosity of less than 20 Mooney units as measured in a Mooney scorch test using a large rotor, a one minute preheat time, a ten minute test time, and a 100° C. test temperature. 
     
     
         11 . The apparatus of  claim 9 , wherein the fluorine-containing polymer comprises a perfluoroelastomer having a Mooney viscosity of less than 20 Mooney units as measured in a Mooney scorch test using a large rotor, a one minute preheat time, a ten minute test time, and a 100° C. test temperature. 
     
     
         12 . The apparatus of  claim 9 , wherein the fluorine-containing polymer comprises a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene having a Mooney viscosity of less than 20 Mooney units as measured in a Mooney scorch test using a large rotor, a one minute preheat time, a ten minute test time, and a 100° C. test temperature 
     
     
         13 . The apparatus of  claim 7 , wherein the sealable chamber comprises a body and lid. 
     
     
         14 . The apparatus of  claim 7 , wherein the sample holder includes a plurality of sample cups. 
     
     
         15 . The apparatus of  claim 7 , further comprising:
 an acoustic reflecting plate positioned between the acoustic transducer and the sample holder such that only a first portion of the acoustic signal generated by the acoustic transducer reaches the sample holder and a second portion of the acoustic signal generated by the transducer is reflected back to the acoustic transducer by the acoustic reflecting plate.   
     
     
         16 . The apparatus of  claim 15 , further comprising a plurality of acoustic transducers. 
     
     
         17 . A method of measuring a downhole characteristic, comprising:
 placing an acoustic transducer in a wellbore; and   using the acoustic transducer to measure a characteristic of a portion of a downhole device, wherein the acoustic transducer comprises:
 a piezoelectric element configured to generate acoustic signals according to an electrical signal that is applied to the piezoelectric element; 
 a backing component contacting a back-side surface of the piezoelectric element; and 
 an encasing material that surrounds the piezoelectric element and the backing component, 
 wherein the backing component comprises a fluorine-containing polymer in which metal particles are incorporated, and 
 the metal particles comprise greater than 40% of the backing component by volume. 
   
     
     
         18 . The method of  claim 17 , wherein the downhole device comprises a packer. 
     
     
         19 . The method of  claim 17 , wherein the electrical signal is supplied from a battery positioned in the wellbore. 
     
     
         20 . An acoustic transducer, comprising:
 a piezoelectric element configured to generate acoustic signals according to an electrical signal that is applied to the piezoelectric element;   a backing component contacting a back-side surface of the piezoelectric element; and   an encasing material that surrounds the piezoelectric element and the backing component,   wherein the backing component includes a fluorine-containing polymer containing metal particles in an amount greater than 40% of the backing component by volume and the fluorine-containing polymer is selected from the group consisting of:   a. a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene having a Mooney viscosity of less than 20 Mooney units as measured in a Mooney scorch test using a large rotor, a one minute preheat time, a ten minute test time, and a 100° C. test temperature;   b. a fluoroelastomer that comprises a di-polymer of vinylidene fluoride and hexafluoropropylene having a Mooney viscosity of less than 20 Mooney units as measured in a Mooney scorch test using a large rotor, a one minute preheat time, a ten minute test time, and a 100° C. test temperature; and   c. a perfluoroelastomer having a Mooney viscosity of less than 20 Mooney units as measured in a Mooney scorch test using a large rotor, a one minute preheat time, a ten minute test time, and a 100° C. test temperature.