Abstract:
A swellable packer construction. A method of forming an annular barrier in a well includes the steps of: embedding a reinforcement material within a swellable seal material to form a seal assembly; and swelling the seal material by contacting the seal material with well fluid. A method of constructing a well packer includes the steps of: embedding a reinforcement material in a swellable seal material to form a seal assembly; and then installing the seal assembly on a base pipe. A swellable packer construction comprises a seal assembly including a swellable seal material having a reinforcement material embedded therein, the seal material being cylindrical shaped and disposed both external and internal relative to the reinforcement material, and the seal material being swellable in response to contact with well fluid.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     The present invention claims the benefit under 35 USC §§119 and 365 of the filing date of International Application No. PCT/US2006/035052, filed Sep. 11, 2006. The entire disclosure of this prior application is incorporated herein by this reference. 
     
    
     BACKGROUND  
       [0002]     The present invention relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a swellable packer construction.  
         [0003]     The benefits of using swellable seal materials in well packers are well known. For example, typical swellable seal materials can conform to irregular well surfaces (such as corroded or damaged casing, or uncased wellbores, etc.) and can be expanded radially outward without use of complex and potentially failure-prone downhole mechanisms.  
         [0004]     Prior methods of constructing swellable well packers typically include molding or otherwise bonding the swellable material onto a tubular base pipe. Differently configured base pipes are used for different situations, for example, where different tensile strengths, different threaded connections, different materials, etc. are required.  
         [0005]     Unfortunately, these prior methods of constructing swellable packers require that many different configurations be manufactured, inventoried, appropriately distributed, etc. This increases the cost of providing suitable swellable packers to the industry, and reduces the convenience of using swellable packers.  
         [0006]     Therefore, it may be seen that improvements are needed in the art of swellable packer construction.  
       SUMMARY  
       [0007]     In carrying out the principles of the present invention, a swellable packer construction is provided which solves at least one problem in the art. One example is described below in which a seal assembly including a swellable seal material may be used on a variety of different base pipe configurations, thereby eliminating the need to manufacture and inventory a separate packer construction for each different base pipe configuration. Another example is described below in which the seal assembly includes a reinforcement material embedded in the swellable seal material, thereby providing a more rigid seal assembly suitable for installation on a base pipe.  
         [0008]     In one aspect of the invention, a method of forming an annular barrier in a subterranean well is provided. The method includes the steps of: embedding a reinforcement material within a swellable seal material to thereby form a seal assembly; and swelling the seal material by contacting the seal material with well fluid in the well.  
         [0009]     In another aspect of the invention, a method of constructing a well packer includes the steps of: embedding a reinforcement material in a swellable seal material to thereby form a seal assembly; and then installing the seal assembly on a base pipe.  
         [0010]     In yet another aspect of the invention, a swellable packer construction comprises a seal assembly including a swellable seal material having a reinforcement material embedded therein. The seal material is cylindrical shaped and is disposed both external and internal relative to the reinforcement material. The seal material is swellable in response to contact with well fluid.  
         [0011]     These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings, in which similar elements are indicated in the various figures using the same reference numbers. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a schematic partially cross-sectional view of a well system embodying principles of the present invention;  
         [0013]      FIG. 2  is an enlarged scale schematic cross-sectional view of a swellable packer construction which embodies principles of the present invention; and  
         [0014]      FIGS. 3-7  are further enlarged scale schematic cross-sectional views of various construction techniques for use in the packer construction of  FIG. 2 . 
     
    
     DETAILED DESCRIPTION  
       [0015]     It is to be understood that the various embodiments of the present invention 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 the present invention. The embodiments are described merely as examples of useful applications of the principles of the invention, which is not limited to any specific details of these embodiments.  
         [0016]     In the following description of the representative embodiments of the invention, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. In general, “above”, “upper”, “upward” and similar terms refer to a direction toward the earth&#39;s surface along a wellbore, and “below”, “lower”, “downward” and similar terms refer to a direction away from the earth&#39;s surface along the wellbore.  
         [0017]     Representatively illustrated in  FIG. 1  is a well system  10  which embodies principles of the present invention. In the well system  10 , a tubular string  12  (such as a production tubing string, liner string, etc.) has been installed in a wellbore  14 . The wellbore  14  may be fully or partially cased (as depicted with casing string  16  in an upper portion of  FIG. 1 ), and/or the wellbore may be fully or partially uncased (as depicted in a lower portion of  FIG. 1 ).  
         [0018]     An annular barrier is formed between the tubular string  12  and the casing string  16  by means of a swellable packer  18 . Another annular barrier is formed between the tubular string  12  and the uncased wellbore  14  by means of another swellable packer  20 .  
         [0019]     However, it should be clearly understood that the packers  18 ,  20  are merely two examples of practical uses of the principles of the invention. Other types of packers may be constructed, and other types of annular barriers may be formed, without departing from the principles of the invention.  
         [0020]     For example, an annular barrier could be formed in conjunction with a tubing, liner or casing hanger, a packer may or may not include an anchoring device for securing a tubular string, a bridge plug or other type of plug may include an annular barrier, etc. Thus, the invention is not limited in any manner to the details of the well system  10  described herein.  
         [0021]     Each of the packers  18 ,  20  includes a seal assembly with a swellable seal material which swells when contacted by an appropriate well fluid. The term “swell” and similar terms (such as “swellable”) are used herein to indicate an increase in volume of a seal material. Typically, this increase in volume is due to incorporation of molecular components of the well fluid into the seal material itself, but other swelling mechanisms or techniques may be used, if desired.  
         [0022]     When the seal material swells in the well system  10 , it expands radially outward into contact with the inner surface of the casing string  16  (in the case of the packer  18 ), or the inner surface of the wellbore  14  (in the case of the packer  20 ). Note that swelling is not the same as expanding, although a seal material may expand as a result of swelling.  
         [0023]     For example, in conventional packers, a seal element may be expanded radially outward by longitudinally compressing the seal element, or by inflating the seal element. In each of these cases, the seal element is expanded without any increase in volume of the seal material of which the seal element is made.  
         [0024]     Various techniques may be used for contacting the swellable seal material with appropriate well fluid for causing swelling of the seal material. The well fluid may already be present in the well when the packers  18 ,  20  are installed in the well, in which case the seal assemblies of the packers preferably include features (such as absorption delaying coatings or membranes, swelling delayed material compositions, etc.) for delaying the swelling of the seal material.  
         [0025]     Alternatively, the well fluid which causes swelling of the seal material may be circulated through the well to the packers  18 ,  20  after the packers are in the well. As another alternative, the well fluid which causes swelling of the seal material may be produced into the wellbore  14  from a formation surrounding the wellbore. Thus, it will be appreciated that any method may be used for causing swelling of the seal material of the packers  18 ,  20  in keeping with the principles of the invention.  
         [0026]     The well fluid which causes swelling of the seal material could be water and/or hydrocarbon fluid. For example, water or hydrocarbon fluid produced from a formation surrounding the wellbore  14  could cause the seal material to swell.  
         [0027]     Various seal materials are known to those skilled in the art, which seal materials swell when contacted with water and/or hydrocarbon fluid, so a comprehensive list of these material will not be presented here. Partial lists of swellable seal materials may be found in U.S. Pat. Nos. 3,385,367 and 7,059,415, and in U.S. Published Application No. 2004-0020662, the entire disclosures of which are incorporated herein by this reference. However, it should be understood that any seal material which swells when contacted by any type of well fluid may be used in keeping with the principles of the invention.  
         [0028]     Referring additionally now to  FIG. 2 , a swellable packer construction  30  which embodies principles of the present invention is representatively illustrated. The packer construction  30  may be used for either of the packers  18 ,  20  in the well system  10 . The packer construction  30  may also be used for any other type of packer, and in any other type of well system, in keeping with the principles of the invention.  
         [0029]     The packer construction  30  includes a seal assembly  32  and a base pipe  34 . The base pipe  34  may be made of any type of material, may be any length or thickness, may have any type of end connections, may be radially expandable, etc. Thus, it is one of the many benefits of the packer construction  30  that various base pipes may be used with a given seal assembly  32 .  
         [0030]     For example, the base pipe  34  could be a length of conventional production tubing, coiled tubing or liner already present at a wellsite. In that case, it would only be necessary to install the seal assembly  32  on the tubing or liner to form the packer construction  30 .  
         [0031]     In this manner, there is no need to manufacture, inventory and distribute different packer constructions for different wellsite applications. Only the seal assembly  32  need be manufactured to suit the different wellsite applications.  
         [0032]     Of course, a complete packer construction  30  could be made for each individual application prior to delivery to a corresponding wellsite. However, even in this case it would not be necessary to inventory each of the separate packer constructions. Instead, the seal assembly  32  could be matched to an appropriate base pipe  34  after the specific application is known.  
         [0033]     When the seal assembly  32  is manufactured, it preferably includes a reinforcement material  36  embedded within a swellable seal material  38 . The reinforcement material  36  preferably provides increased rigidity to the seal assembly  32  for convenient installation on the base pipe  34 .  
         [0034]     Note that the seal material  38  is preferably positioned both external relative to the reinforcement material  36  (for sealing contact with a well surface, such as the casing string  16  or the wellbore  14 ) and internal relative to the reinforcement material (for sealing contact with the base pipe  34 ).  
         [0035]     In another beneficial feature of the packer construction  30 , the seal material  38  preferably contacts the base pipe  34  over substantially the entire length of the seal assembly  32  between its opposite ends. Thus, enhanced sealing contact is provided between the seal assembly  32  and the base pipe  34 , even though the seal assembly may not be molded or otherwise bonded onto the base pipe.  
         [0036]     The reinforcement material  36  is preferably in the form of a cylindrical sleeve, and is preferably made of metal. However, other forms and materials may be used for the reinforcement material  36  in keeping with the principles of the invention.  
         [0037]     The reinforcement material  36  is preferably embedded in the seal material  38  by molding the reinforcement material in the seal material. This method will provide a convenient, integral and economical construction. However, other methods of embedding the reinforcement material  36  in the seal material  38  (such as piecewise construction) may be used in keeping with the principles of the invention.  
         [0038]     End rings  40  may be used to secure the seal assembly  32  on the base pipe  34 , and to prevent extrusion of the seal material  38  in the annular gap between the base pipe and the well surface against which the seal material seals. The end rings  40  may be attached to the base pipe  34  before or after the seal assembly  32  is installed on the base pipe. The end rings  40  may be attached to the base pipe  34  using any appropriate techniques (such as welding, mechanical fasteners, adhesive bonding, etc.).  
         [0039]     Various methods may be used for installing the seal assembly  32  on the base pipe  34 . For example, the base pipe  34  may be inserted longitudinally through an inner passage  42  of the seal assembly  32 . Alternatively, a longitudinal slit (not visible in  FIG. 2 ) may be provided in the seal assembly  32 , so that the base pipe  34  can be installed laterally through the slit into the inner passage  42 . This latter method may be more useful when the seal assembly  32  is very long and/or the base pipe  34  has a rough or irregular outer surface.  
         [0040]     To further enhance the sealing contact between the seal material  38  and the outer surface of the base pipe  34 , a sealant may be used between these elements when the base pipe is installed in the seal assembly  32 . Alternatively, it is possible that the seal material  38  may not sealingly contact the base pipe  34  until the seal material swells in the well.  
         [0041]     An enlarged scale cross-sectional view of one example of the seal assembly  32  is representatively illustrated in  FIG. 3 . In this example, the reinforcement material  36  and the seal material  38  are formed in complete tubular shapes, with the reinforcement material embedded in the seal material. After manufacturing the seal assembly  32 , the appropriate base pipe  34  would preferably be inserted through the inner passage  42  of the seal assembly to form the packer construction  30 .  
         [0042]     A cross-sectional view of another example of the seal assembly  32  is representatively illustrated in  FIG. 4 . In this example, the seal material  38  is formed in a complete tubular shape, but the reinforcement material  36  has a longitudinal slit  44  formed through it.  
         [0043]     This longitudinal slit  44  permits convenient installation of the seal assembly  32  on the base pipe  34 , in a manner described more fully below. In addition, this slit  44  permits the seal assembly  32  to be resealed longitudinally when the seal material  38  swells in the well, as described more fully below.  
         [0044]     Referring additionally now to  FIG. 5 , the seal assembly  32  of  FIG. 4  is representatively illustrated after another longitudinal slit  46  is formed through the seal assembly  32  at the location of the slit  44  in the reinforcement material  36 . The slit  46  in the seal assembly  32  may be formed at any time, for example, when the seal material  38  is molded, or after the seal material is molded, etc.  
         [0045]     The slit  46  permits the seal assembly  32  to be opened up as depicted in  FIG. 6 , so that the base pipe  34  can be inserted laterally through the slit  46  and into the passage  42  (in the direction indicated by the arrow  48 ). Alternatively, the base pipe  34  could be inserted longitudinally through the passage  42  (as with the example of  FIG. 3 ), with the slit  46  enabling the seal assembly  32  to enlarge as needed to accommodate any irregularities on the outer surface of the base pipe and/or to reduce friction between the seal assembly and the base pipe.  
         [0046]     Preferably, the reinforcement material  36  is resilient and will provide a gripping force to secure the seal assembly  32  on the base pipe  34 . However, it is not necessary for the reinforcement material  36  to be resilient or to provide such a gripping force in keeping with the principles of the invention.  
         [0047]     The completed packer construction  30  is depicted in  FIG. 7 , with the base pipe  34  installed in the seal assembly  32 . Note that the slit  46  is closed, or is at least sufficiently closed, so that when the seal material  38  swells in the well the slit will be sealed off and leakage therethrough will be prevented.  
         [0048]     A sealant and/or adhesive may be used in the slit  46 , if desired, to enhance sealing contact therein. A sealant and/or adhesive may also be used between the seal assembly  32  and the base pipe  34  to enhance sealing contact and/or to secure the seal assembly on the base pipe. Clamps, ties, or other attachment devices may also, or alternatively, be used to secure the seal assembly  32  on the base pipe  34 .  
         [0049]     It may now be fully appreciated that the packer construction  30  which incorporates principles of the present invention provides several advances over prior swellable packers. For example, there is no need to manufacture, inventory and distribute different packer constructions for each wellsite application. In addition, the reinforcement material  36  in the seal material  38  provides increased rigidity in the seal assembly  32 . Furthermore, various techniques may be used for conveniently assembling the seal assembly  32  and base pipe  34 .  
         [0050]     Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, 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 the present invention. 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 present invention being limited solely by the appended claims and their equivalents.