Functionally gradient elastomer material for downhole sealing element

Abstract

A sealing device of enhanced configuration for use in downhole in a well. The device may include an element of elastomeric and unitary construction. At the same time, however, the element may include a substantially cured outer shell disposed about a substantially under-cured inner core. Thus, enhanced robustness and durability may be provided to the device in light of downhole conditions without sacrifice to sealable function of the device.

We claim: 
     
         1 . A sealing device for downhole deployment in a well, the device comprising:
 a mandrel;   a first sealing element coupled to the mandrel and being cured to a first curing level; and   a second sealing element coupled to the mandrel and being cured to a second curing level different from the first curing level, wherein the first and second sealing elements are operatively coupled together.   
     
     
         2 . The sealing device of  claim 1 , wherein the first and second sealing elements are formed from a homogeneous material wherein the first sealing element is cured to the first curing level and the second sealing element is cured to the second curing level. 
     
     
         3 . The sealing device of  claim 1 , wherein the first and second sealing elements are discrete pieces of material mechanically coupled together and to the mandrel. 
     
     
         4 . The sealing device of  claim 3  wherein the first sealing component is nested within the second sealing component. 
     
     
         5 . The sealing device of  claim 1 , wherein first and second sealing elements each have a radial cross-sectional shape, wherein the radial cross-sectional shape of the first and second sealing elements is generally similar but the radial cross-sectional shape of the first sealing element is smaller than the radial cross-sectional shape of the second sealing element such that the second sealing element surrounds the first sealing element with a uniform thickness. 
     
     
         6 . The sealing device of  claim 5  wherein the first curing level is lower than the second curing level such that the inner portion defined by the first sealing element has a lower modulus than the second sealing element. 
     
     
         7 . The sealing device of  claim 1  wherein the first curing level is lower than the second curing level such that the first sealing element is configured to improve the sealing characteristics of the sealing device and the second sealing element is configured to resist extrusion. 
     
     
         8 . The sealing device of  claim 1 , wherein the device comprises three or more sealing elements, each cured to a curing level, and wherein at least two of the curing levels of the sealing elements are different. 
     
     
         9 . The sealing device of  claim 1  wherein the first sealing element is an O-ring seal, a T-seal, or a V-seal, and the second sealing element at least partially surrounds the first sealing element. 
     
     
         10 . The sealing device of  claim 1  wherein the first or second sealing element is made of an elastomer such as NBR, HNBR, EPDM, FEPM, FKM, or FFKM. 
     
     
         11 . The sealing device of  claim 1 , further comprising a reinforcement material such as a powder material, fiber material, or a nanoparticle material. 
     
     
         12 . The sealing device of  claim 1 , wherein the first sealing element and second sealing element are formed of an integral material and the curing level varies substantially continuously throughout at least a portion of the elements, such that there is a gradient region within the sealing device. 
     
     
         13 . The sealing device of  claim 12 , wherein the gradient region varies substantially linearly in a predetermined direction throughout the sealing device. 
     
     
         14 . The sealing device of  claim 12 , wherein the gradient region encompasses all of the first sealing element and all of the second sealing element. 
     
     
         15 . The sealing device of  claim 12 , wherein the sealing device is configured for use in a cased hole packer, an open hole packer, or a swell packer. 
     
     
         16 . A functionally gradient elastomer material for use with a packer, the functionally gradient elastomer material comprising:
 a first element having a first characteristic configured to resiliently seal against an exterior surface;   a second element having a second characteristic configured to resist extrusion, wherein the second element resiliently seals against an exterior surface to a lesser degree than the first element, and wherein the first element resists extrusion to a lesser degree than the second element, and further wherein the first and second elements are coupled together such that, when actuated, pressure causes the first and second elements to deform together to form a seal; and   a mandrel coupled to at least one of the first or second elements and configured to support the first and second elements as the functionally gradient elastomer material forms the seal.   
     
     
         17 . The functionally gradient elastomer material of  claim 16 , wherein the first and second elements are formed integrally, the functionally gradient elastomer material further comprising a gradient region between the first and second elements in which the first and second characteristics vary. 
     
     
         18 . The functionally gradient elastomer material of  claim 17 , wherein the gradient varies spatially at least one of linearly, radially, angularly, or axially. 
     
     
         19 . The functionally gradient elastomer material of  claim 16 , wherein the first and second elements are formed of discrete materials. 
     
     
         20 . The functionally gradient elastomer material of  claim 16 , wherein the first characteristic and second characteristic are different levels of curing, reinforcement material, modulus, hardness, strength, elongation, volume swell, or degradation temperature. 
     
     
         21 . A method of forming a sealing device for use with a downhole tool, the method comprising:
 forming a first elastomeric sealing element having a first physical property;   forming a second elastomeric sealing element having a second physical property, wherein the first physical property causes the first elastomeric sealing element to be comparatively more resilient than the second elastomeric sealing element and the second physical characteristic causes the second elastomeric sealing element to be comparatively better at resisting extrusion stresses than the first elastomeric sealing element;   coupling the first and second elastomeric sealing elements together; and   coupling the first and second elastomeric sealing elements to a mandrel configured to support the elastomeric sealing elements as pressure is exerted upon the elastomeric sealing elements to form a seal.   
     
     
         22 . The method of  claim 21 , wherein forming the first elastomeric sealing element comprises curing the elastomeric sealing element to a first level and wherein forming the second elastomeric sealing element comprises curing the elastomeric sealing element to a second level different from the first level. 
     
     
         23 . The method of  claim 21 , wherein forming the first and second elastomeric sealing element comprises integrally forming the first and second elastomeric sealing elements.