Abstract:
A sealing member including a body having a recess; one or more backups extending from the body and tapering over a length thereof; and a sealing element disposed in the recess, the element including one or more steps, each step being adjacent one of the one or more backups and on a surface of the sealing element intended to make contact with a target sealing surface.

Description:
BACKGROUND 
       [0001]    In the drilling and completion arts, sealing of various components and or spaces is important. Sealing annular spaces is quite common and can significantly affect borehole activity or efficiency. There are many and varied types of seals that have been used successfully over the years in many borehole but there is a particular difficulty with respect to high temperature/high pressure applications. Such applications are becoming more common in connection with the use and exploitation of deeper boreholes for such as Carbon Dioxide sequestration, geothermal activities and Petroleum production, for example. 
         [0002]    High temperature environments tend to degrade sealing materials and high pressure is difficult for obvious reasons. Nevertheless, with increasing depths and a relentless pursuit of subterranean business opportunities, the art is always receptive to improvements in sealing technology. 
       SUMMARY 
       [0003]    A sealing member including a body having a recess; one or more backups extending from the body and tapering over a length thereof; and a sealing element disposed in the recess, the element including one or more steps, each step being adjacent one of the one or more backups and on a surface of the sealing element intended to make contact with a target sealing surface. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0004]    Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
           [0005]      FIG. 1  is a cross sectional representation of a portion of a sealing configuration; and 
           [0006]      FIG. 2  is a cross sectional representation of a portion of an alternate embodiment sealing configuration. 
       
    
    
     DETAILED DESCRIPTION 
       [0007]    It is known in the art to urge a member radially outwardly to create a seal with a radially outwardly positioned tubular member. Configurations capable of creating this type of seal are also known to the art. For this reason it is needless to describe such components but rather to focus upon a sealing member portion of a sealing configuration that exemplifies the invention. 
         [0008]    Referring to  FIG. 1 , a first embodiment of a sealing member  10  is illustrated. The member includes a body  12  endowed with one or more seals  14  that will prevent fluid and or pressure migration radially inwardly of the body. As one of skill in the art will recognize, the body includes a tapered surface  16  and hence is configured to ride on a frustoconical member (not shown but a known configuration in the art) to thereby urge the body radially outwardly and into contact with a target surface  18  to be sealed against. The body is composed of one or more materials having good elongation properties such as AISI 8620 annealed metal material. Other materials having similar properties including Polyetheretherketone can also be used. 
         [0009]    The target surface  18  in one embodiment is a casing inside surface. Important to note is that the surface  18  may be not only a smooth easy to seal surface but also may be in for example as-rolled casing having inside dimensional deviations up to about 0.1 inch. Structural aspects of the invention responsible for this benefit are discussed hereunder. 
         [0010]    The body  12  includes a seal element recess  20  sized and configured to receive a seal element  22 . At either longitudinal end of the recess  20  is a backup  30  extending from the body  12 . Upon brief perusal of  FIG. 1 , it will be evident that the backups  30  are unusual. Backups  30  extend for a relatively long distance from the body  12  and taper during that extension. In one embodiment, at least one of the backups  30  embodies two angles over its length, which are identified by  30   a  and  30   b . The change in the angle of the backups  30  provides for increasing the length of the backups to allow for longer engagement with surface  18  without exceeding a drift diameter of the seal member and falls within a range of 5 to 25 degrees. The backups, because of the length of their extension and the continued taper along that extension are quite narrow at terminal ends  32  thereof. The taper employed is selected to ensure that the backups will substantially conform to deviations in the surface  18 . In order to accommodate this result, the taper is in the range of 5 to 15 degrees. 
         [0011]    The configuration of the backups  30 , as described, is beneficial in two ways. First, the longer length of the backups  30  ensure that contact with the surface  18  occurs before the seal element  22  contacts the surface  18  and the second is that because of the thin cross section of the backups near the terminal ends  32 , the backups are capable of seating against inconsistencies in surface  18 . This is particularly beneficial in as-rolled casing, for example, to reduce the possibility of extrusion. The thinner and therefore pliable terminal ends  32  and proximate portions of the backups  30  deform easily into abnormalities of the surface  18 . 
         [0012]    Turning to the seal element  22 , the same comprises, in various embodiments, one or more of a relatively large number of materials such as Fluoro elastomers (FKM), Perfluoro elastomers (FFKM), Hydrogenated Nitrile Butadiene Rubber (HNBR), Nitrile Butadiene Rubber (NBR), Polytetrafluoroethylene, Polyetheretherketone, or other relatively soft material including soft metals such as lead, gold, silver, bronze, copper, etc. 
         [0013]    It will be appreciated from  FIG. 1  that one end  36  of the seal element  22  is configured to closely follow a contour of the recess  20  whereas the other end  38  of the seal element  22  does not closely follow the contour of the recess  20 . Rather, the configuration of end  38  specifically does not follow the contour of the recess proximate thereto. This provides for additional energization of the seal element  22  during and after the setting process. More specifically the configuration as illustrated allows for fluid pressure, which bypasses the backups  30 , to act on end  38  as soon as the seal element  22  contacts surface  18 , that is, when a surface  40  of seal element  22  communicates sufficiently with surface  18  to allow a pressure differential across the sealing member  10  to exist. The pressure that then acts upon end  38 , causes axial compression upon the seal element  22 , energizing the seal element in a similar manner to that of a compression set packer. 
         [0014]    Still referring to  FIG. 1 , it is to be appreciated that the surface  40  includes a step  42  at one end thereof. The step, in an embodiment such as illustrated in  FIG. 1 , will always be at an end of the seal element that comes into contact with the surface  18  last. It will be appreciated that a seal member such as that illustrated is moved axially as it is expanded. The axial movement up the frustocone naturally causes the leading end of the seal element to contact the surface  18  first and begin to drag thereon. Because of the drag, it is possible in prior art devices for the element to extrude over the backups  30  and thereby defeat its purpose. In the invention, the configuration of the seal element  22  is such that drag on the seal surface  40  is insufficient to cause material of element  22  building up enough to crest the backups  30  at end  36  of the member  10 . Rather, the backups  30  at the trailing end of the member  10 , which in the illustrated embodiment of  FIG. 1  is at end  36  of the element  22  will contact and conform to the surface  18  before the element  22  can drag over the backups  30 . The step  42  then is of significant benefit to the art in that it appreciably enhances the ratio of elements set properly to those not set properly. 
         [0015]    Referring now to  FIG. 2 , wherein similar or identical components are numbered using 100 series numbers of those used in connection with the  FIG. 1  embodiment, an alternate embodiment of a sealing member  110  is illustrated. In this embodiment, there are two distinctions over the prior described embodiment of  FIG. 1 . These are: a step  142  on both ends of the element  122 , and that the element  122  closely follows the contour of the recess  120  on both ends  136  and  138  of the element  122 . This embodiment allows for simpler construction of the member  110  as the element  122  does not have a particular orientation for assembly with the body  112 . Rather the element  122  is symmetrical and can be assembled to the body  112  in either direction. 
         [0016]    It is to be noted that in either disclosed embodiment, a bonding agent may be used to secure the element  22  or  122  to the body  12  or  112 . The bonding agent may be placed at an end of the element that closely contours to the recess whether that be at one end ( FIG. 1 ) or at both ends ( FIG. 2 ). It is also possible in some embodiments to bond between the ends  36 / 38 ,  136 / 138 . 
         [0017]    Additionally, in view of thermal expansion of materials, it is desirable in some embodiments to configure the seal element  22 ,  122  to have a resting inside dimension that is smaller than a resting outside dimension of the body  12 ,  112 . This will facilitate maintenance of a sealing interface between the element and the body during exposure to temperatures sufficiently high to cause expansion of the seal element  22 ,  122 . 
         [0018]    While one or more 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.