Abstract:
Disclosed are apparatus and methods for movably securing a radially expandable sand-control screen jacket assembly to a base pipe. The screen jacket assembly is connected to the base pipe with a longitudinally moveable, sand-controlling joint. In use, the joint slides maintain a sand-controlling seal after radial expansion of the sand-control screen jacket assembly.

Description:
TECHNICAL FIELD 
     The present inventions relate to sand-control apparatus for use in subterranean wells, and in particular contemplate improved mechanical apparatus for attaching a sand-control screen jacket assembly to a base pipe and methods of using the same. 
     BACKGROUND OF THE INVENTIONS 
     The control of the movement of sand and gravel into a well bore has been the subject of much importance in the oil production industry. The introduction of sand or gravel into the wellbore commonly occurs under certain well conditions. The introduction of these materials into the well commonly causes problems including plugging and erosion. There have therefore been numerous attempts to prevent the introduction of sand and gravel into the production stream. 
     A common method to prevent the introduction of sand and gravel into the production stream has been a procedure known as gravel packing. In general, this involves placing a selected sand or gravel into the annular space between the wellbore and a base pipe introduced into the wellbore for that purpose. The base pipe contains perforations designed to allow well fluids to flow into the base pipe while excluding other material. A sand-control screen is commonly used in conjunction with a base pipe. An appropriately sized screen is commonly formed into a jacket and wrapped around the outside of the base pipe to prevent the entry of sand. Exemplary apparatus and methods of connecting a sand-control screen jacket assembly to a base pipe are disclosed in U.S. Pat. No. 5,931,232, which is assigned to this assignee and is incorporated herein for all purposes by this reference thereto. 
     One method of enhancing production in a well using a sand-control screen jacket assembly includes causing the radial expansion of the base pipe and surrounding screen jacket assembly by drawing a mechanical expansion tool through the base pipe. The radial expansion of the screen jacket assembly and base pipe is known to cause a related shrinkage in the length of both the base pipe and the screen jacket assembly. Since the base pipe is concentrically enclosed by the screen jacket assembly, the mechanical expander deployed in the base pipe necessarily causes greater expansion in the base pipe than in the surrounding screen jacket assembly. Correspondingly, the base pipe undergoes a greater contraction in length relative to the screen jacket assembly. This differential change in length causes problems such as cracking at the junction between the screen jacket assembly and the base pipe and can lead to the introduction of sand and gravel into the production stream. 
     Due to the aforementioned problems with the introduction of sand and gravel into the production stream, a need exists for apparatus and methods providing a robust mechanical sand-controlling, longitudinally moveable connection between a sand-control screen jacket assembly and a base pipe. Such a connection should withstand downhole production conditions including radial expansion and the related differential longitudinal contraction of the base pipe and sand-control screen jacket assembly. 
     SUMMARY OF THE INVENTIONS 
     In general, the inventions provide apparatus and methods for connecting a sand-control screen jacket assembly to a base pipe while providing for longitudinal movement of the screen jacket assembly relative to the base pipe. 
     The apparatus employs a substantially tubular screen jacket assembly having a first ring affixed to at least one end. A second ring is affixed to the outer surface of the base pipe of the screen jacket assembly wherein the first and second rings have sand-controlling overlapping portions defining a longitudinally movable joint. The joint has a stop integral with the overlapping portions of the first and second rings, which prevents the possibility of longitudinal separation of the screen shroud and base pipe. 
     According to one aspect of the invention the stop comprises a plurality of corresponding screws and slots in the respective overlapping portions of the first and second rings. 
     According to another aspect of the invention, the stop comprises correspondingly opposed surfaces of the respective overlapping portions of the first and second rings. 
     According to yet another aspect of the invention, the ring affixed to the base pipe is attached by a plurality of fasteners such as set screws. 
     According to still other aspects of the invention, the screen jacket assembly has one or more longitudinally deformable pleats or slots. 
     According to another aspect of the invention, the screen jacket assembly has one or more radially expandable pleats. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are incorporated into and form a part of the specification to illustrate several examples of the present inventions. These drawings together with the description serve to explain the principals of the inventions. The drawings are only for the purpose of illustrating preferred and alternative examples of how the inventions can be made and used and are not to be construed as limiting the inventions to only the illustrated and described examples. The various advantages and features of the present inventions will be apparent from a consideration of the drawings in which: 
     FIG. 1 is a longitudinal cross-sectional view of a sand-control screen jacket assembly mechanically connected to a base pipe; 
     FIG. 2 is a close-up longitudinal cross-sectional view of another example of an embodiment of a sand-control screen jacket assembly mechanically connected to a base pipe; 
     FIG. 3 is a close-up longitudinal cross-sectional view of yet another example of an embodiment of a sand-control screen jacket assembly mechanically connected to a base pipe; 
     FIG. 4 is a close-up longitudinal cross-sectional view of still another example of an embodiment of a sand-control screen jacket assembly mechanically connected to a base pipe; 
     FIG. 5 is a close-up longitudinal cross-sectional view of an example of an embodiment of a sand-control screen jacket assembly mechanically connected to a base pipe; 
     FIG. 6 is a close-up longitudinal cross-sectional view of an example of an embodiment of a sand-control screen jacket assembly mechanically connected to a base pipe; 
     FIG. 6A is a transverse cross-sectional view taken along line A—A of FIG. 6; 
     FIG. 6B is a transverse cross-sectional view taken along line B—B of FIG. 6; 
     FIG. 7 is a close-up longitudinal cross-sectional view of an example of another embodiment of a sand-control screen jacket assembly connected to a base pipe. 
     FIG. 8 is a close-up longitudinal cross-sectional view of an example of another embodiment of a sand-control screen jacket assembly connected to a base pipe. 
     FIG. 9 is a close-up longitudinal cross-sectional view of an example of another embodiment of a sand-control screen jacket assembly connected to a base pipe. 
    
    
     DETAILED DESCRIPTION 
     The present inventions are described by reference to drawings showing one or more examples of how the inventions can be made and used. In these drawings, reference characters are used throughout the several views to indicate like or corresponding parts. 
     In the description which follows, like or corresponding parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the invention. In the following description, the terms “upper,” “upward,” “lower,” “below,” “downhole”, “longitudinally” and the like, as used herein, shall mean in relation to the bottom, or furthest extent of, the surrounding wellbore even though the wellbore or portions of it may be deviated or horizontal. Correspondingly, the “transverse” or “radial” orientation shall mean the orientation perpendicular to the longitudinal orientation. “Longitudinally moveable”, in particular, means movement with a longitudinal component, although a transverse component may be present as well. In the discussion which follows generally cylindrical well, pipe and tube components are assumed unless expressed otherwise. The term “sand-control” used herein means the exclusion of particles larger in cross section than a chosen size, whether sand, gravel, mineral, soil, organic matter, or a combination thereof. 
     Referring now to FIGS. 1 through 9 the general structure of a sand-control screen jacket assembly connection  10  utilizing the present inventive concepts is shown. It will be obvious to those skilled in the arts that the opposite end (not shown) of the screen jacket assembly  20  may be constructed in any conventional manner or in the same manner as the end described. A base pipe  12  is threadably connected to a collar  14  at either end. Each collar  14  is in turn connected to a pipe string (not shown) used in a subterranean well. The base pipe  12  has a plurality of perforations  18  through which fluids in the well enter the interior of the base pipe  12 . The number and configuration of the perforations  18  is not critical to the invention so long as a balance between fluid production and pipe integrity is maintained. A sand-control screen jacket assembly  20  concentrically surrounds the base pipe  12 . The sand-control screen jacket assembly  20  has one or more concentric screens  21 , with or without a layer of packed sand between concentric screen layers, and typically, a surrounding screen shroud  22 . The exact configuration of the screen jacket assembly is not critical to the invention and may be varied by those skilled in the arts according to well conditions. For example, the number and mesh sizes of screen may be varied, or the shroud may be omitted entirely. The screen jacket assembly may be radially expandable. Some examples of variations in the configuration of the screen, shroud, and screen jacket assembly, are further discussed below. 
     The preferred embodiment of the invention shown with an unexpanded screen jacket assembly in FIG. 2 has a substantially tubular screen shroud  22  with a first ring  24  affixed to one end, preferably by a weld  26 . A second ring  28  is affixed to the outer surface of the base pipe  12 , also preferably by a weld  26 . In this embodiment, the second ring  28  is preferably made of a plurality of segments  30  (FIG. 1) captured in a groove  32  provided for this purpose in the base pipe  12 . The first and second rings  24 ,  28  have respective overlapping portions  25 ,  27 . The corresponding overlapping portions  25 ,  27  define a longitudinally slidable joint  34  sufficiently close-fitting to exclude sand particles of a size to also be excluded by the screen  21 , but not necessarily fluid tight. As the base pipe  12  and screen jacket assembly  20  are radially expanded with corresponding differential changes in length, the overlapping portions  25 ,  27  of the joint  34  slide longitudinally with respect to one another while maintaining their sand-controlling fit. An elastomeric seal element  33  may be inserted at slidable joint  34 . The longitudinal separation of the screen jacket assembly  20  and the base pipe  12  is prevented by a stop  36 , preferably an integral portion of the second ring  28 . 
     FIG. 3 depicts an example of another embodiment of an apparatus using the invention. The screen jacket assembly connection  10  in FIG. 3 has a substantially tubular screen shroud  22  with a first ring  24  affixed to one end, preferably by a weld  26 . The embodiment using the invention depicted in FIG. 3 has a second ring  38  attached to the base pipe  12  with a weld  26 . Additionally, the groove  32  of FIG. 2 is omitted from the embodiment of FIG.  3 . An alternative configuration of the first ring  24  is also shown in FIG.  3 . The first and second rings  24 ,  38  have respective overlapping portions  25 ,  37 . The corresponding overlapping portions  25 ,  37  define a longitudinally slidable joint  34  sufficiently close-fitting to exclude sand particles of a size to also be excluded by the screen  21 , but not necessarily fluid tight. As the base pipe  12  and screen jacket assembly  20  are radially expanded with corresponding differential changes in length, the overlapping portions  25 ,  37  of the joint  34  slide longitudinally with respect to one another while maintaining their sand-controlling fit. An elastomeric seal element  33  may be inserted at slidable joint  34 . The longitudinal separation of the screen jacket assembly  20  and the base pipe  12  is prevented by a stop  36 , preferably an integral portion of the second ring  38 . 
     FIG. 4 depicts an example of another embodiment of an apparatus using the invention. The embodiment shown in FIG. 4 has a substantially tubular screen shroud  22  with a first ring  24  affixed to one end, preferably by a weld  26 . A second ring  40  is attached to the base pipe  12  with a plurality of set screws  41 . A longitudinally slidable joint  34  is defined by the inner surface  25  of the first ring  24  and the corresponding outer surface  13  of the base pipe  12 . The longitudinally slidable joint  34  is sufficiently close-fitting to exclude sand particles of a size to also be excluded by the screen  21 , but not necessarily fluid tight. As the base pipe  12  and screen jacket assembly  20  are radially expanded with corresponding differential changes in length, the overlapping portions  25 ,  13  of the joint  34  slide longitudinally with respect to one another while maintaining their sand-controlling fit. An elastomeric seal element  33  may be inserted at slidable joint  34 . The longitudinal separation of the screen jacket assembly  20  and the base pipe  12  is prevented by the stop  36  defined by the transverse alignment of the first ring  24  and second ring  40 . 
     An alternative embodiment using the invention is shown in FIG. 5. A substantially tubular screen shroud  22  has a first ring  54  affixed to one end, preferably by a weld  26 . Alternatively, the first ring  54  may be integral to shroud  22 . A second ring  55  is affixed to the outer surface of the base pipe  13 , also preferably by a weld  26 . The first and second rings  54 ,  55  have respective overlapping portions  56 ,  57 . The corresponding overlapping portions  56 ,  57  define a longitudinally slidable joint  34  sufficiently close-fitting to exclude sand particles of a size to also be excluded by the screen  21 , but not necessarily fluid tight. As the base pipe  12  and screen jacket assembly  20  are radially expanded with corresponding differential changes in length, the overlapping portions  56 ,  57  of the joint  34  slide longitudinally with respect to one another while maintaining their sand-controlling fit. An elastomeric seal element  33  may be inserted at slidable joint  34 . The longitudinal separation of the screen jacket assembly  20  and the base pipe  12  is prevented by stop assembly  36 , preferably made from a plurality of corresponding screws  58  and slots  59  in the respective overlapping portions  56 ,  57  of the first and second rings  54 ,  55 . 
     FIG. 6 illustrates an alternative embodiment using the invention. The screen  21  has longitudinal pleats  61  to facilitate radial expansion. More extensive pleats or corrugations may also be provided for added surface area. As in the embodiments described with reference to FIGS. 1-5, the embodiment of FIG. 6 may be used with screen jacket assemblies  20  made with various combinations of screen  21  layers and a screen shroud  60 . The embodiment has an end connection assembly  63  with a first ring  64  welded to the base pipe  12 . A second ring  65  has a captured portion  66  captured between an overlapping portion  67  of the first ring and the base pipe  12 . The corresponding overlapping portions  66 ,  67  define a longitudinally slidable joint  34  sufficiently close-fitting to exclude sand particles of a size to also be excluded by the screen  62 , but not necessarily fluid tight. As the base pipe  12  and screen jacket assembly  20  are radially expanded with corresponding differential changes in length, the overlapping portions  66 ,  67  of the joint  34  slide longitudinally with respect to one another while maintaining their sand-controlling fit. An elastomeric seal element  33  may be inserted at slidable joint  34 . The second ring  65  has an integral transition portion  68  welded to the screen jacket assembly  20 . As can best be seen in FIG. 6A, taken in cross section along line A—A of FIG. 6, the captured portion  66  of the second ring  65  is cylindrical in cross section where it meets the base pipe  12 . FIG. 6B, taken in cross-section along line B—B of FIG. 6, illustrates that the transition portion  68  of the second ring is pleated or corrugated in cross-section where it is welded to the screen jacket assembly  20 . A third ring  69  having a transition portion substantially similar to that of the second ring  65  may be welded to the opposite, preferably downhole, end of the screen jacket assembly  20  and the surface  13  of the base pipe  12 . Alternatively, both ends of the screen jacket assembly may employ an end connection assembly  63 . 
     It will be clear to those skilled in the art that the structure shown and described with referrence to rings  65 ,  66  or  69  in FIG. 6 can be adapted for the use of longitudinally pleated screens or shrouds in combination with any of the above-described embodiments shown and discussed with reference to FIGS. 1-5. 
     FIG. 7 depicts yet another alternative embodiment of a screen shroud  70  using the invention. This embodiment incorporates longitudinally deformable slots  71  in the screen shroud  70 . Of course, the embodiment shown and described may be used with a screen jacket assembly made with various combinations of screen and screen shroud layers. The shroud  70  is welded  26  at its end portions  72  to the base pipe  12 . The inner surface  73  of the end portions  72  of the shroud  70  containing the transverse slots  71  is in flush contact with the outer surface  13  of the base pipe  12 . The transverse slots  71  are designed to facilitate longitudinal movement of the shroud  70  relative to the base pipe  12  defining a longitudinally, deformably slidable joint  34  sufficiently close-fitting to exclude sand particles of a size to also be excluded by the screen  21 , but not necessarily fluid tight. As the base pipe  12  and screen jacket assembly  20  are radially expanded with corresponding differential changes in length, the transverse slots  71  of the joint  34  deform longitudinally while maintaining their sand-controlling fit. An elastomeric seal element  33  may be inserted at slidable joint  34 . As in the other embodiments described herein, a screen  21  is captured between the shroud  70  and the base pipe  12 . Of course, the exact orientation and location of the slots is not critical to the invention so long as the slots are configured to incorporate the property of longitudinal movability, for example, helical slots may be used. Optionally, spacer rods  74  may be included between the screen  21  and base pipe  12  to facilitate fluid flow. 
     FIGS. 8 and 9 depict other alternative embodiments using the invention with a screen jacket assembly  20  having a screen shroud  80  concentrically surrounding one or more screens  21 . The screen shroud  80  has one or more longitudinally deformable pleats  82 . The exact orientation and location of the pleats  82  is not critical to the invention so long as the pleats are configured to incorporate the property of longitudinal deformability, for example, transverse pleats  82  or helical pleats may be used. The pleated screen shroud  80  shown is welded  26  to the base pipe at either end  84 , capturing the screen  21  and allowing space  86  for sliding movement at the ends  84 . The pleats  82  may be arranged on the shroud  80  overlapping the screen  21 , as shown in FIG. 9, such that the pleats  82  act as a spacer, maintaining fluid flow space  90  between the screen shroud  80  and screen  21 . 
     Further referring to FIGS. 8-9, the pleats  82  are designed to facilitate longitudinal movement of the shroud  80  relative to the base pipe  12  defining a longitudinally, deformably slidable joint  34  sufficiently close-fitting to exclude sand particles of a size to also be excluded by the screen  21 , but not necessarily fluid tight. As the base pipe  12  and screen jacket assembly  20  are radially expanded with corresponding differential changes in length, the pleats  82  of the shroud  80  deform longitudinally while maintaining their sand-controlling fit. As in the other embodiments described herein, a screen  21  is captured between the shroud  80  and the base pipe  12 . Of course, the exact orientation and location of the pleats is not critical to the invention so long as the pleats are configured to incorporate the property of longitudinal deformability, for example, helical pleats may be used. Optionally, spacer rods  74  may be included between the screen  21  and base pipe  12  to facilitate fluid flow. 
     The embodiments shown and described above are only exemplary. Many details are often found in the art such as: screen mesh size, configurations and materials, the use of longitudinal rods or other spacers between a screen and another surface, or the use of a packed sand layer between screen layers. Therefore, many such details are neither shown nor described. It is not claimed that all of the details, parts, elements, or steps described and shown were invented herein. Even though numerous characteristics and advantages of the present inventions have been set forth in the foregoing description, together with details of the structure and function of the inventions, the disclosure is illustrative only, and changes may be made in the detail, especially in matters of shape, size and arrangement of the parts within the principles of the inventions to the full extent indicated by the broad general meaning of the terms used in the attached claims. 
     The restrictive description and drawings of the specific examples above do not point out what an infringement of this patent would be, but are to provide at least one explanation of how to make and use the inventions. The limits of the inventions and the bounds of the patent protection are measured by and defined in the following claims.