Patent Publication Number: US-7584795-B2

Title: Sealed branch wellbore transition joint

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   The present application is a continuation-in-part of U.S. application Ser. No. 10/767,656 filed Jan. 29, 2004 now U.S. Pat. No. 7,213,652. The entire disclosure of this prior application is incorporated herein by this reference. 

   BACKGROUND 
   The present invention relates generally to operations performed and equipment utilized in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a sealed branch wellbore transition joint. 
   A transition joint is used in completing some multilateral wells, for example, in TAML “Level 3” multilateral completions. As the name implies, the transition joint provides a useful transition between a parent wellbore and a branch wellbore drilled-outwardly from the parent wellbore. 
   Unfortunately, it is a difficult problem to seal off a formation surrounding the intersection between the parent and branch wellbores from the parent wellbore. Where a sufficient seal is not provided, formation fines and sand can make their way into the parent wellbore, where they can plug or erode production equipment and cause other problems. 
   Therefore, it may be seen that it would be beneficial to provide improved well completion systems and methods. Such systems and methods could include an improved sealed branch wellbore transition joint. 
   SUMMARY 
   In carrying out the principles of the present invention, in accordance with an embodiment thereof, a sealed branch wellbore transition joint is provided for use in well completion systems and methods. A swelling sealing material is preferably used on the transition joint in order to seal off a formation surrounding an intersection between parent and branch wellbores. 
   In one aspect of the invention, a method of completing a well having intersecting wellbores is provided. The method includes the steps of: positioning a diverter in one of the wellbores; diverting an assembly from the wellbore into another wellbore; and swelling a sealing material on the assembly, so that a seal is formed between the assembly and the diverter. 
   The sealing material may be used to form other seals in the method, as well. For example, a seal may be formed between the diverter and a wellbore, between the assembly and a window at the intersection of the wellbores, and/or between the assembly and a wellbore. In addition, the assembly may be expanded prior to, after, or during swelling of the sealing material. 
   In another aspect of the invention, a completion system is provided for a well having intersecting wellbores. The system includes a diverter positioned in one of the wellbores, and an assembly extending laterally across the wellbore. A sealing material on the assembly is swollen so that a seal is formed between the assembly and the diverter. 
   In a further aspect of the invention, a method of completing a well having a branch wellbore extending outwardly from a window in a parent wellbore is provided. The method includes the steps of: positioning an assembly in the window; and swelling a sealing material on the assembly. A seal is formed between the assembly and the window by the swelling sealing material. 
   In a still further aspect of the invention, a completion system for a well having a branch wellbore extending outwardly from a window in a parent wellbore is provided. The system includes a tubular string having a portion positioned within the window, and a sealing material on the tubular string portion. The sealing material swells in the well to thereby form a seal between the tubular string portion and the window. 
   In yet another aspect of the invention, a completion system for a well having a branch wellbore extending outwardly from a window in a parent wellbore includes an assembly positioned in the parent wellbore, the assembly having an opening formed through a sidewall thereof. The opening is aligned with the window. A sealing material is positioned on the assembly. The sealing material swells in the well to thereby form a seal circumferentially about the opening. 
   In a further aspect of the invention, a method of completing a well having a branch wellbore extending outwardly from a window in a parent wellbore includes the steps of: positioning an assembly in the parent wellbore; forming an opening through a sidewall of the assembly; aligning the assembly with the window; and swelling a sealing material on the assembly, so that a seal is formed about the opening. 
   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 
       FIG. 1  is a schematic partially cross-sectional view of a first well completion system embodying principles of the present invention; 
       FIG. 2  is a schematic partially cross-sectional view of the first system, wherein a branch wellbore transition joint has been sealed; 
       FIG. 3  is a schematic partially cross-sectional view of a second well completion system embodying principles of the present invention; 
       FIG. 4  is a schematic partially cross-sectional view of the second system, wherein an intersection between wellbores has been sealed; and 
       FIG. 5  is a somewhat enlarged scale schematic cross-sectional view of an alternate configuration of the first system. 
   

   DETAILED DESCRIPTION 
   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. 
   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. 
   As depicted in  FIG. 1 , a main or parent wellbore  12  has been drilled, and then lined with protective casing  14 . The parent wellbore  12  may extend continuously to the earth&#39;s surface, or it may be a branch of another wellbore. It is not necessary in keeping with the principles of the invention for the parent wellbore  12  to be cased, since it could be completed open hole if desired. If the parent wellbore  12  is cased, then the wellbore can be considered the interior of the casing  14 . 
   A branch wellbore  16  is drilled extending outwardly from a window  18  formed through a sidewall of the casing  14 . The window  18  can be formed before or after the casing  14  is installed in the parent wellbore  12 . For example, the window  18  could be formed by anchoring a whipstock (not shown in  FIG. 1 , see  FIG. 5 ) in the casing  14 , and then deflecting a mill laterally off of the whipstock to cut the window through the casing sidewall. 
   A formation or zone  20  surrounds the intersection between the parent and branch wellbores  12 ,  16 . In order to seal off the formation  20  from the interior of the parent wellbore  12 , while also providing a useful transition between the parent and branch wellbores  12 ,  16 , an assembly  22  is positioned in the window  18 . The assembly  22  is depicted in  FIG. 1  as including a tubular string  24  having a transition joint  26  interconnected therein. 
   A lower end of the tubular string  24  is deflected into the branch wellbore  16 , for example, by using the whipstock or other deflector positioned in the parent wellbore  12 . The tubular string  24  could be cemented in the branch wellbore  16 , if desired. 
   The transition joint  26  has an opening  28  formed through a sidewall thereof. The opening  28  may be formed in the sidewall of the transition joint  26  before or after the transition joint is installed in the well. The opening  28  provides fluid communication (and preferably access) between an interior of the tubular string  24  and the parent wellbore  12  external to the tubular string below the window  18 . 
   A sealing material  30  is provided on the transition joint  26 . Preferably, the sealing material  30  is provided in the form of a coating adhered externally to the transition joint  26 . However, other methods of attaching the sealing material  30  to the transition joint  26  may be used in keeping with the principles of the invention. 
   The sealing material  30  swells when exposed to fluid in the well. Preferably, the sealing material  30  increases in volume and expands radially outward when a particular fluid contacts the sealing material in the well. For example, the sealing material  30  could swell in response to exposure to hydrocarbon fluid (such as oil or gas), or in response to exposure to water in the well. 
   The sealing material  30  could be made of a specialized rubber compound, or it could be made of other materials. Acceptable materials for the sealing material  30  are available from Easywell A. S. of Stavanger, Norway. 
   Referring additionally now to  FIG. 2 , the system  10  is depicted after the sealing material  30  has swollen in the window  18 . Note that a seal  32  is now formed by the swollen sealing material  30  between the transition joint  26  and the window  18 . This seal  32  may be used to prevent fines, sand, etc. from migrating from the formation  20  into the parent wellbore  12 . The tubular string  24  could be cemented in the branch wellbore  16  before or after the seal  32  is formed. 
   In addition, the swollen sealing material  30  can (but does not necessarily) provide another seal  34  between the transition joint  26  and the casing  14  in the parent wellbore  12 . This seal  34  can be used as an annular barrier above the opening  28 . Note that the opening  28  is conveniently positioned between the seals  32 ,  34  for providing fluid communication between the interior of the tubular string  24  and the parent wellbore  12  below the window  18 . 
   Referring additionally now to  FIG. 3 , another completion system  40  embodying principles of the invention is representatively illustrated. The system  40  is similar in many respects to the system  10  described above, and so elements of the system  40  which are similar to those described above are indicated in  FIG. 3  using the same reference numbers. 
   The system  40  differs from the system  10  in at least one significant respect in that, instead of positioning the tubular string  24  in the parent and branch wellbores  12 ,  16 , an assembly  42  is positioned in the parent wellbore opposite the window  18 . The assembly  42  includes a tubular structure  44  having the sealing material  30  externally secured thereto. In addition, a tubular string  46 , such as a liner string, is positioned in the branch wellbore  16 . 
   The tubular string  46  is preferably positioned in the branch wellbore  16  prior to positioning the assembly  42  in the parent wellbore  12 . The tubular string  46  may be cemented in the branch wellbore  16 , for example, between the window  18  and a packer  48  set in the branch wellbore, or the tubular string may be otherwise cemented or left uncemented in the branch wellbore. An upper end  50  of the tubular string  46  may extend to the parent wellbore  12 , where it may be cut off, such as by use of a washover tool, etc. 
   When the assembly  42  is positioned in the parent wellbore  12 , it may have an opening  52  formed through its sidewall. This opening  52  may be rotationally aligned with the window  18  by engagement between a latch  54  of the assembly  42  and an orienting profile  56  of the casing string  14 . This engagement may also anchor the assembly  42  in the casing string  14 . 
   Alternatively, the opening  52  could be formed after the assembly  42  has been positioned in the parent wellbore  12 . For example, a deflector (such as a whipstock) could be secured in the assembly  42  and used to deflect a cutting tool (such as a mill) to form the opening  52  through the assembly sidewall after the assembly is anchored in the casing string  14 . Furthermore, the opening  52  could be formed through the sidewall of the assembly  42  after the sealing material  30  has swelled. 
   Referring additionally now to  FIG. 4 , the system  40  is representatively illustrated after the sealing material  30  has swelled. The sealing material  30  may be swollen by exposure to fluid in the well, such as hydrocarbon fluid or water, etc. A volume of the sealing material  30  increases as it swells. 
   A sealed flowpath  58  is now provided between the branch wellbore  16  and the parent wellbore  12  through an interior of the assembly  42 . This flowpath  58  is isolated from the formation  20  surrounding the intersection between the parent and branch wellbores  12 ,  16 . 
   Specifically, the sealing material  30  now forms a seal  60  between the assembly  42  and the interior of the casing string  14  circumferentially about the opening  52  and circumferentially about the window  18 . The sealing material  30  also preferably sealingly engages the upper end  50  of the tubular string  46  and seals circumferentially thereabout. In addition, the swollen sealing material  30  forms an annular seal  62  between the tubular structure  44  and the interior of the casing string  14  both above and below the window  18 . 
   Referring additionally now to  FIG. 5 , the system  10  is representatively illustrated in an alternate configuration. In this alternate configuration, the sealing material  30  forms a seal  66  at an upper end of a diverter  68  positioned in the parent wellbore  12 . 
   As described above, the diverter  68  could be used in forming the window  18  and/or in deflecting the lower end of the assembly  22  into the branch wellbore  16  from the parent wellbore  12 . Thus, the diverter  68  could be of the type known to those skilled in the art as a drilling whipstock, completions diverter, or another type of diverter. 
   Note that the diverter  68  has a passage  70  formed completely longitudinally through the diverter. In this manner, the passage  70  permits flow communication and access between the parent wellbore  12  above and below the window  18 . 
   As with the system  10  as depicted in  FIGS. 1 &amp; 2 , the opening  28  may be formed prior to or after installing the assembly  22 . Any method may be used for forming the opening  28 , including but not limited to milling, perforating (e.g., prior to or instead of milling), chemical cutting, etc. 
   The seal  66  is formed at the top of the diverter  68  and extends circumferentially about the passage  70 , so that sealed communication is provided between the passage and the interior of the assembly  22 . This seal  66  may serve as a backup to the seal  32 , in order to prevent sand, fines, debris, etc. from entering the parent wellbore  12  from the formation  20  and the wellbore junction, or the seal  66  could be used in place of the seal  32 . In the latter case, use of the seal  66  may eliminate any need to seal against the window  18 , which may have an irregular interior surface that could be difficult to seal against. 
   In some situations, it may be desired to flow cement or another hardenable sealing substance into the wellbore junction area to seal about the tubular string  24 . In that case, the seal  66  may be used to prevent the cement or other substance from flowing into the passage  70  and remainder of the parent wellbore  12 . 
   The sealing material  30  could also be used on the diverter  68  to form a seal  72  between the diverter and the interior of the casing string  14 . For example, the diverter  68  could be provided with a latch and orienting profile (similar to the latch  54  and orienting profile  56  described above) to orient and anchor the diverter in the casing string  14 , and the sealing material  30  could swell to seal between the diverter and the interior of the casing string (similar to the manner in which the sealing material seals between the tubular structure  44  and the interior of the casing string as depicted in  FIG. 4 ). 
   In the configuration of the system  10  depicted in  FIG. 5 , the tubular string  24  is preferably expanded radially outward after being positioned at the wellbore junction with its lower end in the branch wellbore  16 . In this manner, clearance between the tubular string  24  and the window  18 , casing string  14  and upper end of the diverter  68  can be reduced. This reduced clearance will enhance the formation and maintenance of the seals  32 ,  34 ,  66 . 
   Various methods may be used to expand the tubular string  24 . For example, a swage, drift, rollers, etc. may be used to mechanically deform the tubular string  24  radially outward. As another example, increased pressure may be applied internally to the tubular string  24  to inflate it. Any method of expanding the tubular string  24  may be used in keeping with the principles of the invention. 
   Swelling of the sealing material  30  may be initiated before, during and/or after the expansion of the tubular string  24 . Preferably, the swelling is initiated after the clearance between the tubular string  24  and the structure(s) (casing string  14 , window  18  and/or diverter  68 ) against which the sealing material  30  will seal has been reduced. 
   Note that this expansion process may be used in the system  10  depicted in  FIGS. 1 &amp; 2  and described above, and may also be used in the system  40  depicted in  FIGS. 3 &amp; 4  and described above. Thus, the tubular string  24  could be expanded in the system  10  of  FIGS. 1 &amp; 2 , and the tubular structure  44  could be expanded in the system  40  of  FIGS. 3 &amp; 4 . 
   In addition, although the systems  10 ,  40  have been described above as including the seals  32 ,  34 ,  60 ,  62 ,  66 , it should be clearly understood that it is not necessary for the respective systems to include all or any particular combination of these seals. Any one, and any combination of, the seals  32 ,  34 ,  60 ,  62 ,  66 , and any other seals may be provided in the systems  10 ,  40  in keeping with the principles of the invention. 
   Furthermore, although the sealing material  30  has been depicted in the drawings as being a single element, it will be readily appreciated that the sealing material could be formed in multiple separate elements, if desired. For example, any of the seals  32 ,  34 ,  60 ,  62 ,  66 , and any combination of these, could be formed by separate portions of the sealing material  30 . 
   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 these specific embodiments, and such changes are within the scope of 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.