Abstract:
A method of making a shape memory structure includes, commingling elastic material with viscoelastic material, and forming a structure with the commingled materials. Altering a shape of the structure, altering an environment the structure is exposed to, to lock in the altered shape of the structure via hardening of the viscoelastic material until the structure is exposed to another environment that softens the viscoelastic material.

Description:
BACKGROUND 
     Filtering contaminates from flowing fluids is a common exercise in systems involved in transportation of fluids. Many such systems employ screens as the filtering mechanism. Screens that expand to substantially fill an annular gap, for example, between concentric tubulars, is another common practice. Some of these systems use swaging equipment to radially expand the screen. Although such equipment serves its purpose it has limitations, including a limited amount of potential expansion, complex and costly equipment and an inability to expand to fill a nonsymmetrical space. Apparatuses that overcome these and other limitations with existing systems are therefore desirable to operators in the field. 
     BRIEF DESCRIPTION 
     Disclosed herein is a shape memory structure. The structure includes, an elastic material, and a viscoelastic material commingled with the elastic material. The shape memory structure is reformable from a first shape to a second shape upon exposure to a change in environment that softens the viscoelastic material thereby allowing the shape memory structure to creep under stress stored in the elastic material. 
     Further disclosed herein is a conformable screen. The screen includes, a structure having, an elastic material and a viscoelastic material commingled with the elastic material, a filter material, and a permeable tubular. The structure is reformable from a first shape to a second shape upon exposure to a first environment that softens the viscoelastic material to thereby allow the structure to creep under stress stored in the elastic material. The filter material is positioned within the structure and is compressible such that the filter material is maintained in a smaller volume when the structure is in the first shape than when the structure is in the second shape. The permeable tubular is in operable communication with the structure such that fluid flowable through one of the filter material and permeable tubular are subsequently flowable through the other of the filter material and the permeable tubular 
     Further disclosed herein is a method of making a shape memory structure. The method includes, commingling elastic material with viscoelastic material, and forming a structure with the commingled materials. Altering a shape of the structure, altering an environment the structure is exposed to, to lock in the altered shape of the structure via hardening of the viscoelastic material until the structure is exposed to another environment that softens the viscoelastic material. 
     Further disclosed herein is a method of making a conformable screen. The method includes, commingling elastic material with viscoelastic material, forming a structure with the commingled materials, surrounding a permeable tubular with the structure, and positioning filter material within the structure. The method further includes, compacting the structure and the filter material into a compaction and altering an environment the compaction is exposed to, to maintain a volume of the compaction until the compaction is exposed to another environment 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  depicts a perspective view of a conformable screen disclosed herein; 
         FIG. 2  depicts a perspective view of the conformable screen of  FIG. 1  with the filter material removed in an un-compacted configuration; 
         FIG. 3  depicts a perspective view of the conformable screen of  FIG. 2  in a compacted configuration; 
         FIG. 4  depicts a partial cross sectional view of the conformable screen of  FIG. 2  with the filter material present; 
         FIG. 5  depicts a partial cross sectional view of the conformable screen of  FIG. 3  with the filter material present; and 
         FIG. 6  depicts a schematic view of commingled fibers of elastic and viscoelastic materials disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     Referring to  FIGS. 1-5 , an embodiment of a conformable screen disclosed herein is illustrated at  10 . The conformable screen  10  includes a structure  14  made of at least two commingled materials, an elastic material  18  and a viscoelastic material  22  (shown in greater detail in  FIG. 6 ). The structure  14 , illustrated herein as a facetted structure, is reformable from a first shape, or compaction (as shown in  FIGS. 3 and 5 ) to a second shape (as shown in  FIGS. 2 and 4 ) upon exposure to an environment that softens the viscoelastic material  22  thereby allowing the facetted structure  14  to creep under stress stored in the elastic material  18 . The conformable screen  10  further includes a filter material  26  positioned within the facetted structure  14 . The filter material  26  may have a mat or foam structure, such as a polyester fiber batting or an open-cell polyurethane form, for example, although embodiments are not limited to these structures. The filter material  26  is volumetrically compactable or compressible and once compacted can be maintained at a smaller volume until allowed to return to its un-compacted larger volume. The filter material  26 , being positioned within the facetted structure  14 , can be maintained in the compacted condition by the facetted structure  14 . The facetted structure  14  and the filter material  26  are positioned radially of a permeable tubular illustrated in this embodiment as a perforated tubular  30  of the conformable screen  10 . As such, fluid is able to flow through perforations  34  in the perforated tubular  30  after flowing through the filter material  26 , and being filtered in the process. Alternately, fluid flowing in a reverse direction could flow through the filter material  26  after flowing through the perforations  34 . 
     Referring specifically to  FIGS. 4 and 5 , the conformable screen  10  is shown employed in a borehole  38  in an earth formation  42  such as when used in a hydrocarbon recovery application or a carbon dioxide sequestration application, for example. The conformable screen  10  is run into the borehole  38  when in the first shape, or compaction, wherein the facetted structure  14  is hardened and maintains the filter material  26  in the smaller volume configuration. The conformable screen  10  has a first radial dimension  46  when in the first shape and a second radial dimension  50  when in the second shape. The first radial dimension  46  is smaller than the second radial dimension  50 , thereby providing radial clearance between the conformable screen  10  and the borehole  38  while running the conformable screen  10  therewithin. Once the conformable screen  10  is positioned at a selected location within the borehole  38 , exposure of the conformable screen  10 , and more particularly of the facetted structure  14 , to an alternate environment causes a softening of the viscoelastic material  22  thereby allowing stresses within the elastic material  18  to cause the facetted structure  14  to change from the first shape to the second shape (it should be noted that, although not required, the filter material can also provide loads that assist in returning the facetted structure  14  from the first shape to the second shape). In so doing the conformable screen  10  undergoes a change from the first radial dimension  46  toward the second radial dimension  50  resulting in contact between the filter material  26  and walls  54  of the borehole  38  in the process. The contact between the filter material  26  and the walls  54  minimizes or eliminates annular clearance  58  therebetween and erosion that could result due to fluid flow if the annular clearance  58  were allowed to exist. The contact between the filter material  26  and the walls  54  also provides support to the walls  54  lessening the potential for undesirable conditions such as collapses and voids in the formation  42 , for example. 
     Referring to  FIG. 6 , an embodiment illustrating how the elastic material  18  and the viscoelastic material  22  may be commingled is illustrated. In this embodiment the elastic material  18  and the viscoelastic material  22  are formed into fibers  62  or fibrils such that the fibers  62  of the viscoelastic material  22  effectively surround the fibers  62  of the elastic material  18 . The commingled fibers  62  are formed into the facetted structure  14 . The elastic material  18  has different chemical, mechanical and structural characteristics to provide the facetted structure  14  with the shape memory properties described above. The elastic material  18  may be one of aramid, glass, boron, basalt, carbon, graphite, quartz, liquid crystal polymer, aluminum, titanium and steel, for example that has a relatively high modulus to provide structure and memory of the original shape to the facetted structure  14 . 
     The viscoelastic material  22  on the other hand may be a thermoplastic polymer such as polyether ether ketone (PEEK), for example, that melts around the fibers  62  of the elastic material  14  during fabrication. The viscoelastic material  22  provides the capacity to be softened in some environments and hardened in others. In the example of the thermoplastic polymer for the viscoelastic material  22  temperature is the changeable environment. As such, heating will soften the viscoelastic material  22  allowing it to creep under loads such as compaction loads applied to cause the facetted structure  14  to be reshaped from the second shape to the first shape. Cooling of the facetted structure  14  allows the viscoelastic material  22  to harden and lock in the first shape until the environment (temperature) is increased to again soften the viscoelastic material  22  thereby allowing it to again creep under load. By configuring the facetted structure  14  and in particular the elastic material  18  therewithin to undergo only elastic deformation when reshaped from the second shape to the first shape, the elastic material  18  will maintain a load on the viscoelastic material  22  all the while that the structure is locked in the first shape. It is this stress locked in the elastic material  18  that allows the facetted structure  14  to creep back from the first shape to the second shape once the viscoelastic material  22  has again been softened by the increase in temperature. 
     Although the embodiment illustrated herein employs a thermoplastic polymer as the viscoelastic material  22  that hardens and then softens in response to changes in temperature, alternate embodiments could be employed that use other changes in environment to cause the viscoelastic material  22  to harden and soften. Examples include materials that respond to changes in humidity and changes in available plasticizers. 
     While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.