Patent Publication Number: US-7213652-B2

Title: Sealed branch wellbore transition joint

Description:
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 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 another 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. 

   
     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; and 
       FIG. 4  is a schematic partially cross-sectional view of the second system, wherein an intersection between wellbores has been sealed. 
   

   DETAILED DESCRIPTION 
   Representatively illustrated in  FIG. 1  is a well completion system  10  which embodies principles of the present invention. In the following description of the system  10  and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. In particular, the term “above” means relatively closer to the earth&#39;s surface along a wellbore, and the term “below” means relatively farther from the earth&#39;s surface along a wellbore. Additionally, 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. 
   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 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 a 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 rubber compound, or it could be made of other materials. 
   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 . 
   Of course, a person skilled in the art would, upon a careful consideration of the above description of a representative embodiment of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to this specific embodiment, 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.