Patent Publication Number: US-9896898-B2

Title: Packer end ring with polymer gripping device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a national stage under 35 USC 371 of International Application No. PCT/IB2012/000394, filed on 1 Mar. 2012. The entire disclosure of this prior application is incorporated herein by this reference. 
     TECHNICAL FIELD 
     This disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in one example described below, more particularly provides a packer end ring with a polymer gripping device for gripping a base pipe. 
     BACKGROUND 
     Packers are used in wells to seal off annuli formed between tubular strings, or between a tubular string and another surface, such as a wall of a wellbore. It is important to construct packers so that they can reliably withstand substantial differential pressure, but it is also important to construct packers in an economical and expeditious manner. 
     Therefore, it will be appreciated that improvements are continually needed in the art of constructing packers for use in wells. 
     SUMMARY 
     In this disclosure, systems and methods are provided which bring improvements to the art of constructing packers. An example is described below in which a gripping device is contained in an end ring, so that the gripping device grips a base pipe and prevents longitudinal displacement of a seal element relative to the base pipe. 
     A packer is provided to the art by the disclosure below. In one example, the packer can include an end ring positioned proximate a seal element on a base pipe, and a gripping device positioned in an annular space between the end ring and the base pipe. The gripping device can comprise a polymer composition material. 
     A method of constructing a packer is also described below. In an example, the method comprises: positioning an end ring on a base pipe, and then injecting a gripping device into an annular space between the end ring and the base pipe, whereby the gripping device grips the base pipe. 
     Another method of constructing a packer can include: positioning an end ring on a base pipe, and positioning a gripping device in an annular space between the end ring and the base pipe, so that the gripping device grips the base pipe, the gripping device comprising a polymer composition material. 
     These and other features, advantages and benefits will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the disclosure below and the accompanying drawings, in which similar elements are indicated in the various figures using the same reference numbers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a representative cross-sectional view of a well system and associated method which can embody principles of this disclosure. 
         FIG. 2  is an enlarged scale representative cross-sectional view of a packer which may be used in the system and method of  FIG. 1 , and which can embody the principles of this disclosure. 
         FIG. 3  is a further enlarged scale representative cross-sectional view of a portion of the packer. 
         FIG. 4  is a representative cross-sectional view of an end ring of the packer. 
     
    
    
     DETAILED DESCRIPTION 
     Representatively illustrated in  FIG. 1  is a system  10  for use with a subterranean well, and an associated method, which can embody principles of this disclosure. However, it should be clearly understood that the system  10  and method are merely one example of an application of the principles of this disclosure in practice, and a wide variety of other examples are possible. Therefore, the scope of this disclosure is not limited at all to the details of the system  10  and method described herein and/or depicted in the drawings. 
     In the  FIG. 1  example, a packer  12  is interconnected in a tubular string  14  and positioned in a wellbore  16 . The packer  12  includes a seal element  18  which extends radially outward into sealing engagement with the wellbore  16 , thereby sealing off an annulus  20  formed radially between the tubular string  14  and the wellbore  16 . 
     In this example, the wellbore  16  is lined with casing  22  and cement  24 . In other examples, the wellbore  16  could be uncased or open hole, in which case the seal element  18  could sealingly engage a wall  26  of an earth formation  28  penetrated by the wellbore  16 . 
     The seal element  18  can comprise a swellable material which swells in response to contact with a particular fluid in the well. The term “swell” (and similar terms, such as, “swellable,” “swelling,” etc.) is used herein to indicate an increase in volume of a material. A seal element can expand outward without swelling (e.g., as in inflatable or compression-set packers, etc.). However, if the material is to be considered swollen, the seal element material itself must increase in volume. 
     Preferably, the swellable material swells when it is contacted with a particular swelling fluid (e.g., oil, gas, other hydrocarbons, water, etc.) in the well. The swelling fluid may already be present in the well, or it may be introduced after installation of the packer  12  in the well, or it may be carried into the well with the packer, etc. The swellable material could instead swell in response to exposure to a particular temperature, or upon passage of a period of time, or in response to another stimulus, etc. 
     End rings  30  longitudinally straddle the seal element  18  on a base pipe  32 , in order to restrict longitudinal displacement of the seal element  18  on the base pipe  32 . In most situations, it is desired for the end rings  30  to substantially prevent any displacement of the seal element  18  relative to the base pipe  32 , so that a desired differential pressure can be sealed against in the annulus  20 . 
     The end rings  30  may directly abut opposite longitudinal ends of the seal element  18  as depicted in  FIG. 1 . In other examples, components such as backup rings, etc. may be interposed between the end rings  30  and the seal element  18 . 
     In further examples, multiple seal elements  18  could be straddled by the end rings  30 , and an end ring could be positioned between a pair of seal elements. Thus, it should be clearly understood that the scope of this disclosure is not limited at all to any of the details of the packer  12 , or seal element  18 , end rings  30  and base pipe  32 , as illustrated in the drawings or described herein. 
     Referring additionally now to  FIG. 2 , an enlarged scale cross-sectional view of the packer  12 , apart from the remainder of the  FIG. 1  system  10 , is representatively illustrated. The packer  12  could, however, be used in other systems and methods, in keeping with the scope of this disclosure. 
     In this view, it may be seen that the seal element  18  comprises a swellable seal material  34 , and encircles the base pipe  32 . The base pipe  32  may be provided with end connectors (not shown) for interconnecting the packer  12  in the tubular string  14 . 
     The end rings  30  are positioned at opposite ends of the seal element  18 . The end rings  30  can serve to protect the seal element  18  as the packer  12  is being conveyed into the wellbore  16 , as well as to prevent displacement of the seal element  18  relative to the base pipe  32 . 
     In the  FIG. 2  example, a gripping device  36  is positioned in each of the end rings  30 . The gripping devices  36  secure the end rings  30  against longitudinal displacement relative to the base pipe  32 , so that the seal element  18  is also secured against longitudinal displacement relative to the base pipe. 
     A further enlarged scale cross-sectional view of a portion of the packer  12  is representatively illustrated in  FIG. 3 . In this view, further details of the end ring  30  and gripping device  36  may be more clearly seen. 
     The gripping device  36  in the  FIG. 3  example is interposed radially between the end ring  30  and the base pipe  32 . The gripping device  36  can adhesively bond to an exterior surface  44  on the base pipe  32  and/or to an interior surface  38  in the end ring  30 . 
     Preferably, the gripping device  36  comprises a polymer composition material  42 , which is injected into an annular space  46  formed radially between the end ring  30  and the base pipe  32 , after the end ring has been positioned on the base pipe. Set screws or another type of centralizers  40  are used to centralize the end ring  30  relative to the base pipe  32 . 
     The centralizers  40  can also retain the end rings  30  in position (longitudinally, rotationally and laterally) relative to the base pipe  32  while the polymer composition “sets” or hardens in the annular space  46  between the end ring and the base pipe. Preferably, a shear strength of the material  42  increases after it has been injected into the annular space  46 . 
     Since the centralizers  40  may only be desired for positioning the end ring  30  on the base pipe  32 , it is preferably not necessary for special materials to be used in the centralizers. For example, relatively high cost materials, such as Inconel, etc., may not be needed in the centralizers  40 . 
     In addition, fewer centralizers  40  may be needed in the end ring  30  of the packer  12 , as compared to a conventional swellable packer in which many set screws are used to prevent longitudinal displacement of a seal element and an end ring in a well. 
     Suitable polymer compositions for use as the material  42  can include PROTECH CRB™ and PROTECH DRB™ casing centralizer resin marketed by Halliburton Energy Services, Inc. of Duncan, Okla. USA, and BELZONE 1591™ marketed by Belzona Inc. of Miami, Fla. USA. Rubber (preferably vulcanized) can be used in the gripping device  36 , if desired. 
     In some examples, the material  42  may comprise a swellable material so that, as the material swells, it applies an increased gripping force between the end ring  30  and the base pipe  32 . The material  42  could swell prior to, during and/or after installation of the packer  12  in the wellbore  16 . 
     In some examples, the material  42  may not be injected between the end ring  30  and the base pipe  32 , and in other examples the material may not be inserted between the end ring and the base pipe after the end ring is positioned on the base pipe. Thus, it should be understood that the scope of this disclosure is not limited to the specific details of the examples described herein and depicted in the drawings. 
     When the gripping device  36  engages the external surface  44  on the base pipe  32 , the gripping device also closes off a radial gap G between the end ring  30  and the base pipe. This can prevent extrusion of the seal element  18  through the gap G, which can increase a differential pressure resisting capability of the packer  12 . 
     A further increase in the differential pressure resisting capability is provided by internal inclined surfaces  48  which taper radially inwardly toward opposite ends of the end ring  30 . These surfaces  48  tend to compress the gripping device  36  between the end ring  30  and the base pipe  32  (and thereby increase the gripping force applied between the end ring and the base pipe) in response to longitudinal displacement of the end ring relative to the base pipe, or in response to swelling of the material  42 . 
     A still further increase in the differential pressure resisting capability can be obtained by including reinforcement in the material  42 . For example, if the shear strength of the material  42  limits the gripping capability of the device  36 , inclusion of a reinforcement having an increased shear strength in the material can increase the gripping capability. 
     In some examples, the reinforcement could comprise very small particles, and in other examples the reinforcement could comprise relatively large elements. The relatively large elements (e.g., steel spheres, etc.) could be larger than the gap G between the end ring  30  and the base pipe  32 . This can aid in closing off the gap G to extrusion, and in enhancing the shear strength of the material  42 . 
     Referring additionally now to  FIG. 4 , the end ring  30  is representatively illustrated, apart from the packer  12 . The end ring  30  may be used with packers other than the packer  12 , in keeping with the scope of this disclosure. 
     In the  FIG. 4  example, four threaded openings  50  (one of which is not visible) are used to receive the centralizers  40 . Of course, if another type of centralizer is used (e.g., biasing devices, etc.), then the threaded openings  50  may not be used. Any number of the openings  50  and/or centralizers  40  may be used, as desired. 
     One or more of the openings  50  (or another opening, etc.) may be used to inject the material  42  into the annular space  46  between the end ring  30  and the base pipe  32 . If the material  42  is not injected into the annular space  46 , then another device may be used to retain the material between the end ring  30  and the base pipe  32 . 
     It may now be fully appreciated that the above disclosure provides significant advances to the art of constructing packers for use with a well. In examples described above, the end rings  30  and gripping devices  36  can effectively retain the seal element  18  on the base pipe  32 , while being economical to manufacture and convenient to install. 
     The above disclosure provides to the art an improved packer  12 . In one example, the packer  12  can include an end ring  30  positioned proximate a seal element  18  on a base pipe  32 , and a gripping device  36  positioned in an annular space  46  between the end ring  30  and the base pipe  32 , the gripping device  36  comprising a polymer composition material  42 . 
     The polymer composition material  42  may be injected between the end ring  30  and the base pipe  32 . The polymer composition material  42  may set and/or harden in the annular space  46 . A shear strength of the polymer composition material  42  can increase in the annular space  46 . 
     The polymer composition material  42  can comprise a swellable material. The polymer composition material  42  may swell and thereby apply increased gripping force to the base pipe  32 . 
     The gripping device  36  may encircle the base pipe  32  and be compressed radially inward by a surface  48  formed in the end ring  30 . The gripping device  36  can increasingly grip the base pipe  32  in response to longitudinal displacement of the end ring  30  relative to the base pipe  32 . 
     The seal element  18  can comprise a swellable material which swells in response to contact with a fluid. 
     The gripping device  36  may close off a gap G formed radially between the base pipe  32  and the end ring  30 . 
     The packer can also include a reinforcement in the polymer composition material  42 . The reinforcement can have a dimension larger than the gap G formed radially between the base pipe  32  and the end ring  30 . 
     A method of constructing a packer  12  is also described above. In one example, the method can include positioning an end ring  30  on a base pipe  32 , and then injecting a gripping device  36  into an annular space  46  between the end ring  30  and the base pipe  32 , whereby the gripping device  36  grips the base pipe  32 . 
     The method can also include the gripping device  36  swelling, thereby increasing a gripping force applied by the gripping device  36  to the base pipe  32 . 
     Another method of constructing a packer  12  is described above. The method can include positioning an end ring  30  on a base pipe  32 , and positioning a gripping device  36  in an annular space  46  between the end ring  30  and the base pipe  32 , so that the gripping device  36  grips the base pipe  32 , the gripping device  36  comprising a polymer composition material  42 . 
     The gripping device positioning can be performed after the end ring positioning. The gripping device positioning may be performed concurrently with the end ring positioning. 
     Although various examples have been described above, with each example having certain features, it should be understood that it is not necessary for a particular feature of one example to be used exclusively with that example. Instead, any of the features described above and/or depicted in the drawings can be combined with any of the examples, in addition to or in substitution for any of the other features of those examples. One example&#39;s features are not mutually exclusive to another example&#39;s features. Instead, the scope of this disclosure encompasses any combination of any of the features. 
     Although each example described above includes a certain combination of features, it should be understood that it is not necessary for all features of an example to be used. Instead, any of the features described above can be used, without any other particular feature or features also being used. 
     It should be understood that the various embodiments described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of this disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments. 
     In the above description of the representative examples, directional terms (such as “above,” “below,” “upper,” “lower,” etc.) are used for convenience in referring to the accompanying drawings. However, it should be clearly understood that the scope of this disclosure is not limited to any particular directions described herein. 
     The terms “including,” “includes,” “comprising,” “comprises,” and similar terms are used in a non-limiting sense in this specification. For example, if a system, method, apparatus, device, etc., is described as “including” a certain feature or element, the system, method, apparatus, device, etc., can include that feature or element, and can also include other features or elements. Similarly, the term “comprises” is considered to mean “comprises, but is not limited to.” 
     Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of this disclosure. For example, structures disclosed as being separately formed can, in other examples, be integrally formed and vice versa. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the invention being limited solely by the appended claims and their equivalents.