Thermally expanding sealing elements

Abstract

A sealing element can be used to create a seal in a wellbore or components of a downhole tool. The sealing element can include an elastomer matrix and a substance embedded within the elastomer that expands at a phase change temperature. The substance can be an organic-based substance, such as a polymeric plastic, a thermoplastic, or a wax. The organic-based substance can expand at a temperature greater than or equal to the phase change temperature. The substance can also be a metal-based substance. The metal-based substance can expand at a temperature less than or equal to the phase change temperature. After expansion, the substance can fill small gaps or cracks formed in the elastomer matrix from temperature fluctuations. The sealing element can be included on a downhole tool. The sealing element can be an O-ring or a gasket or included on packer assembly, a plug, or a liner hanger.

1 . A well system comprising:
 a wellbore that penetrates a subterranean formation; and   a downhole tool comprising a sealing element, wherein the sealing element comprises:
 an elastomer matrix; and 
 a substance embedded within the elastomer matrix, wherein the substance expands at a phase change temperature, wherein the substance expands with a decrease in temperature at or below the phase change temperature, wherein the substance is a metal-based substance consisting of pure metals selected from bismuth, gallium, or germanium or consisting of a metal alloy, wherein the metal alloy comprises bismuth, gallium, or germanium in the greatest percentage of the metal alloy. 
   
     
     
         2 . The well system according to  claim 1 , wherein the downhole tool is selected from a sleeve, a valve, a sensor, an actuator, a telemetry tool, a pressure balancing seal, a packer assembly, a plug, or a liner hanger. 
     
     
         3 . The well system according to  claim 1 , wherein the sealing element creates a seal between components of the downhole tool, and wherein the sealing element is an O-ring, gland seal, stack seal, or gasket. 
     
     
         4 . The well system according to  claim 1 , wherein the sealing element creates a seal between an outside of a mandrel of the downhole tool and the inside of a wall of the wellbore or the inside of a tubing string, and wherein the downhole tool is a packer assembly, a liner hanger, or a plug. 
     
     
         5 . The well system according to  claim 1 , wherein an elastomer of the elastomer matrix is a non-reactive polymer, a degradable polymer, or a polymer that swells in the presence of a fluid. 
     
     
         6 .- 13 . (canceled) 
     
     
         14 . The well system according to  claim 1 , wherein the sealing element further comprises a second metal-based substance, wherein the second metal-based substance has a different phase change temperature than the metal-based substance. 
     
     
         15 . The well system according to  claim 1 , wherein the sealing element further comprises a second substance, and wherein the second substance expands with an increase in temperature at or above a phase change temperature. 
     
     
         16 . The well system according to  claim 1 , wherein the substance is selected such that the substance expands at least 1% in volume. 
     
     
         17 . The well system according to  claim 1 , wherein the substance is in the form of particles having a particle size in the range of 10 millimeters to 1,000 nanometers. 
     
     
         18 . The well system according to  claim 17 , wherein the particles are interspersed throughout the elastomer matrix. 
     
     
         19 . A method of creating a seal within a wellbore comprising:
 introducing a downhole tool into the wellbore, wherein the downhole tool comprises a sealing element, wherein the sealing element comprises:
 an elastomer matrix; and 
 a substance embedded within the elastomer matrix, wherein the substance expands at a phase change temperature, wherein the substance expands with a decrease in temperature at or below the phase change temperature, wherein the substance is a metal-based substance consisting of pure metals selected from bismuth, gallium, or germanium or consisting of a metal alloy, wherein the metal alloy comprises bismuth, gallium, or germanium in the greatest percentage of the metal alloy; and 
   causing or allowing the sealing element to create the seal within the wellbore.   
     
     
         20 . A downhole tool comprising:
 a mandrel; and   a sealing element located adjacent to the mandrel, wherein the sealing element comprises:
 an elastomer matrix; and 
 a substance embedded within the elastomer matrix, wherein the substance expands at a phase change temperature, wherein the substance expands with a decrease in temperature at or below the phase change temperature, wherein the substance is a metal-based substance consisting of pure metals selected from bismuth, gallium, or germanium or consisting of a metal alloy, wherein the metal alloy comprises bismuth, gallium, or germanium in the greatest percentage of the metal alloy. 
   
     
     
         21 . The well system according to  claim 15 , wherein the second substance is an organic-based substance. 
     
     
         22 . The well system according to  claim 21 , wherein the organic-based substance is selected from the group consisting of: a polymeric plastic; a thermoplastic comprising acrylonitrile butadiene styrene, polypropylene, nylon 6/6, acetal, polycarbonate, or polyester; a semi-crystalline organic-based substance; or a wax comprising paraffin or stearic acid. 
     
     
         23 . The well system according to  claim 21 , wherein the organic-based substance is in the form of particles, and wherein the particles are encapsulated in a shell. 
     
     
         24 . The downhole tool according to  claim 20 , wherein an elastomer of the elastomer matrix is a non-reactive polymer, a degradable polymer, or a polymer that swells in the presence of a fluid. 
     
     
         25 . The downhole tool according to  claim 20 , wherein the sealing element further comprises a second metal-based substance, wherein the second metal-based substance has a different phase change temperature than the metal-based substance. 
     
     
         26 . The downhole tool according to  claim 20 , wherein the sealing element further comprises a second substance, and wherein the second substance expands with an increase in temperature at or above a phase change temperature. 
     
     
         27 . The downhole tool according to  claim 26 , wherein the second substance is an organic-based substance. 
     
     
         28 . The downhole tool according to  claim 27 , wherein the organic-based substance is selected from the group consisting of: a polymeric plastic; a thermoplastic comprising acrylonitrile butadiene styrene, polypropylene, nylon 6/6, acetal, polycarbonate, or polyester; a semi-crystalline organic-based substance; or a wax comprising paraffin or stearic acid.