Abstract:
A swellable material seal includes a quantity of swellable material disposed in a geometric configuration; and a plurality of openings in the material to enhance wettability thereof by a swelling fluid.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No.: 60/991,546, filed Nov. 30, 2007; also from U.S. Provisional Application Ser. No. 60/941,221, filed May 31, 2007, and from U.S. Non Provisional Application Ser. No. 12/126,055, filed May 23, 2008, the entire contents of each of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Swellable materials have been used to assist in setting seals or as seals themselves in various industries. Such materials are capable of generating a contact force against a nearby a structure which is capable of either of the noted uses of setting or sealing, or in some cases both, when exposed to a swelling fluid reactive with the swelling material. 
         [0003]    Swelling can occur through absorption or chemical reaction. In applications where a higher degree of swelling, for either purpose is needed, difficulty has been experienced as sufficient volumetric change has not been reliably achievable and in addition when higher volumetric change is attempted, the material itself loses physical integrity thus compromising the ultimate goal of the application. 
       SUMMARY 
       [0004]    A swellable material seal includes a quantity of swellable material disposed in a geometric configuration; and a plurality of openings in the material to enhance wettability thereof by a swelling fluid. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
           [0006]      FIG. 1  is a schematic perspective cross-sectional representation of a prior art swellable seal; 
           [0007]      FIG. 2  is a schematic cross-sectional view of one embodiment of an improved swelling seal as described herein; 
           [0008]      FIG. 2   a  is a cross-sectional view of the embodiment of  FIG. 2  taken along section line  2   a - 2   a;    
           [0009]      FIG. 3  is a schematic cross-sectional view of a second embodiment of an improved swelling seal as described herein; 
           [0010]      FIG. 3   a  is a cross-sectional view of the embodiment of  FIG. 3  taken along section line  3   a - 3   a;    
           [0011]      FIG. 4  is a schematic cross-sectional view of a third embodiment of an improved swelling seal as described herein; 
           [0012]      FIG. 4   a  is a cross-sectional view of the third embodiment of  FIG. 4  taken along section line  4   a - 4   a;    
           [0013]      FIGS. 4   b - 4   f  are cross-sectional end views of the embodiment of  FIG. 4  illustrating alternate layouts for the fabric bits; 
           [0014]      FIG. 5  is a schematic cross-sectional view of a fourth embodiment of an improved swelling seal as described herein; 
           [0015]      FIG. 5   a  is a cross-sectional view of the fourth embodiment of  FIG. 5  taken along section line  5   a - 5   a;    
           [0016]      FIG. 6  is a schematic cross-sectional view of a fifth embodiment of an improved swelling seal as described herein; 
           [0017]      FIG. 6   a  is a cross-sectional view of the fifth embodiment of  FIG. 6  taken along section line  6   a - 6   a;    
           [0018]      FIG. 7  is a schematic cross-sectional view of a sixth embodiment of an improved swelling seal as described herein; 
           [0019]      FIG. 7   a  is a cross-sectional view of the sixth embodiment of  FIG. 7  taken along section line  7   a - 7   a;    
           [0020]      FIG. 8  is a perspective cross-sectional schematic view of a seventh embodiment disclosed herein; 
           [0021]      FIG. 9  is a cross sectional schematic view of an eighth embodiment related to that of  FIG. 8 ; 
           [0022]      FIG. 10  is a plan view of a portion of  FIG. 9  as indicated by view line  10 - 10 ; 
           [0023]      FIG. 11  is a cross-sectional view of an ninth embodiment disclosed herein; 
           [0024]      FIG. 12  is a cross-sectional view of a tenth embodiment disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Referring to  FIG. 1  (prior art), one of the problems associated with higher volumetric expansions of swellable materials is that the material itself when configured for use as an element such as an annular seal  10  for example, is bonded or otherwise mounted to a mandrel  12 , generally in a way that reduces access of swelling fluid to the swellable material. In other words, the surfaces of an exemplary annular seal that are contactable by swelling fluid are an outside dimension surface  14  of the seal and end surfaces  16  and  18  at the axial ends of the seal. An inside dimension surface  20  of the seal is relatively protected from contact with swelling fluid applied to the annular seal  10 . This is due to whatever means has been used to mount the annular seal to the mandrel. Resultantly, the exposed surfaces of the swellable material  14 ,  16 ,  18  must expand more significantly to achieve contact with an opposing structure (not shown) than they would have to have done if a greater proportion of the swellable material were “wettable” by the swelling fluid. More specifically, swelling would occur to a greater extent and more evenly if a greater percentage of the original volume of the material could be affected by the swelling fluid. Greater distribution of the swelling fluid throughout the volume of the swellable material increases the potential contact pressure generatable by the swellable material, and reduces spongyness of the swelled swellable material. Such sponginess can often be experienced when a greater expansion of some parts of the swellable material than others makes up for the lack of swelling in those other parts of the swellable material. A swellable material as contemplated herein may be an elastomeric material such as rubber, for example, swelling EPDM, swelling Nitrile, etc. 
         [0026]    In accordance with the teachings hereof, fibrous material is embedded in the swellable material. This has two desirable effects. 1) The fibrous material provides a fluid pathway facilitating movement of the swelling fluid into an interior volume of the swellable material, thereby wetting areas of the volume otherwise insulated from the swelling fluid and, 2) the fibrous material lends mechanical strength to the swellable material, especially after swelling. Fibrous materials contemplated for use herein include but are not limited Kevlar fiber, cotton fiber, etc. each of which have at least one of wicking properties and absorptive properties of for example water or oil. Other fibrous materials include but are not limited to hollow fiber, bicomponent fiber, etc. and act as capillary tubes resulting in swelling fluid transmission to otherwise insulated portions of the swellable material. Such tubes may be long or short or both and may also be used simply as conveyors that move fluid from one end to the other end, or may also be permeable along their respective lengths so that they supply swelling fluid along their lengths to the swellable material. Each of the exemplary fibrous materials listed above also exhibits mechanical properties that enhance the strength of a swellable material into which they are embedded. Increasing the mechanical strength of the swellable material is desirable to improve extrusion resistance, among other things. 
         [0027]    Referring to  FIGS. 2 and 2   a , a first embodiment of the improved swellable material is illustrated in the form of an annular seal  110  mounted at an outside diameter of a mandrel  112 . Fibrous material  130  is visible in the cross section of the seal  110 . As will be evidenced from the drawing, the embodiment utilizes a random distribution of fibrous material  130  within the seal  110 . The fibrous material and swellable material of the seal  110  may be completely homogenously mixed or may be less so depending upon the desired level of homogeneity of swelling of the swellable material of the seal  110 . The fibrous material  130  may be of short fibers, long fibers or both as desired and may be mixed with the swellable material at a time prior to that material becoming relatively non-mixable in form. Stated alternately, the fibrous material  130  is mixed with the swellable material at a point in processing of the swellable material when mixing is possible and in one embodiment easiest to accomplish. The fibrous material  130  acts to wick the swelling fluid into the volume of the swellable material to enhance the wettability of the swellable material and therefore the degree of swelling of the material. 
         [0028]    Referring to  FIGS. 3 and 3   a , another embodiment of the improved swellable material is illustrated in the form of an annular seal  210  mounted at an outside dimension of a mandrel  212 . Fibrous material  230  is visible in the cross section of the seal  210 . It will be appreciated from the drawing  FIGS. 3 and 3   a  that the distribution pattern of fibrous material  230  in the swellable material of seal  210  is in a layered format. The layered format comprises individual fibers  232  laid axially of the element, and in one alternative embodiment comprises fibers grouped with a number of other individual fibers laid side-by-side and axially of the seal  210  as a pad  234 . The layout for this embodiment is best viewed in  FIG. 3   a  where it is apparent that various groups of fibers are laid at differing radial distances from the inside dimension  220  of seal  210 . 
         [0029]    Referring to  FIGS. 4 and 4   a , a third embodiment of the improved material, illustrated in the form of an annular seal  310 , is mounted at an outside dimension of a mandrel  312 . Fibrous material  330  is visible in the cross section of seal  310  in  FIG. 3 . In this embodiment, the fibrous material is arranged as a woven or non woven fabric. Each bit of fabric embedded in the swellable material is about 0.25 in 2  or more. The bits are embedded in a number of possible patterns some examples of which are illustrated in  FIGS. 4   b ,  4   c ,  4   d ,  4   e  and  4   f.    
         [0030]    Referring to  FIGS. 5 and 5   a  and  6  and  6   a , another embodiment of the improved swellable material is illustrated in the form of an annular seal  410  mounted at an outside dimension of a mandrel  412 . Fibrous material  430  is visible in the cross section of the seal  410 . It will be appreciated from the drawing  FIGS. 5 and 5   a  that the distribution pattern of fibrous material  430  in the swellable material of seal  410  is in a layered format. In this embodiment the distribution of a fibrous material is a woven or non woven fabric arranged frustoconically through the swellable material seal  410 . This is best viewed in  FIG. 5 . It will be appreciated that one or more frustocones of fabric may be employed and that they may be arranged such that the frustocone angles outwardly as radial dimension from an axis of the element grows or angles inwardly as radial dimension from an axis of the element grows as in  FIG. 5  or  FIG. 6 , respectively, or in any combination of  FIGS. 5 and 6 . 
         [0031]    Referring now to  FIG. 7  another embodiment is illustrated very similar to the embodiment of  FIG. 4  but utilizing corrugated fabric instead of planar fabric. 
         [0032]    In another embodiment, referring to  FIG. 8 , the swellable annular seal material  510 , disposed upon mandrel  512  is configured to have a number of openings  550  therein. The openings may be radially directed as shown or may have different angularity if desired or if useful for a particular application. The openings  550  may be of any desired depth, including completely through the swellable material  510 , and the greater the depth the greater the wettability of the swellable material. In one embodiment and as shown, the openings  550  are in a grid pattern. It is further noted that the density of the openings  550  may be greater or less than what is shown in  FIG. 8 . 
         [0033]    Referring to  FIGS. 9 and 10 , a related embodiment to that of  FIG. 8  is illustrated. In the embodiment of  FIG. 9 , not only do the openings  550  extend to the surface of the mandrel  512 , but in addition, they are aligned with openings  560  in the mandrel itself. Where the openings  550  are aligned with openings  560 , the openings  550  can be used as swellable material conduits once the swellable material has been swelled into contact with another structure. For example, where openings  550  are aligned with openings  560  and the “another structure” is the borehole wall (not shown), an isolated swellable material conduit directly from the mandrel to the borehole wall can be created upon swelling of the swellable material. When used in conjunction with a flow isolation configuration in the mandrel itself, operations such as fracing, stimulation, or any other operation where fluid is applied from the mandrel to another structure can be undertaken in a specific area while maintaining isolation from any other area radially outwardly of the mandrel. Such a configuration of the swellable material and the underlying mandrel opening  560  can be obtained by punching an opening in the swellable material either before or after applying the swellable material to the mandrel and then drilling the opening  560  through the mandrel in register with the opening  550 . It is also possible to simply apply the swellable material opening  550  over an existing opening  560  in the mandrel  512 . Further, it is pointed out that although the embodiment is illustrated with the openings  550  extending completely through the swellable material, there are applications where it is desirable to extend the openings to close to the surface of the mandrel  512  but to not actually reach it. In such configuration the openings  560  will be sealed until a desired time when an appropriate diverter device allows pressure from a fluid to act on the swellable material from within the mandrel  512  and rupture the relatively thin material left in place over the opening  560 . 
         [0034]    In yet another embodiment, referring to  FIG. 11 , a configuration of individual components of swellable seal material  610  is illustrated. This embodiment combines the concept of primary sealing structures and backup rings with swellable material construction and additionally with an understanding of exposed surface area of the swellable material. As has been clearly indicated hereinabove, causing the swellable material to be wettable improves the swelling characteristics thereof. Increasing the wettable surface area to volume ratio certainly increases the wettability. In this embodiment, the seal  610  is segmented into a primary seal  652 , a set of cups  654  and a set of backups  656 . The configuration of the segments causes the primary seal to remain sealed similarly to packers that use backups for the same reason but in this case, it has been discovered that swellable material in segments begets an advantage if so configured. Swellable material alone could be employed or any of the improved swellable materials disclosed hereinabove could be employed in the configuration of  FIG. 11 . 
         [0035]    Finally,  FIG. 12  is a reversed configuration of the concept of  FIG. 11  where the center piece  752  acts as the backup,  754  are the cups and  756  are additional backups. 
         [0036]    While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.