Patent Publication Number: US-8991508-B2

Title: Pack off device with cable feedthrough

Description:
BACKGROUND 
     The use of packers and pack-off devices is widespread throughout the downhole drilling and completions industry. Packers or pack-off devices come in a myriad of styles for handling a variety of downhole conditions, environments, and structures. One example that necessitates a unique arrangement for a pack-off device is where one or more cables, lines, fibers, wires, or other auxiliary components must be fed through the pack-off device in addition to a primary tubular string, e.g., as with a pack-off device arranged to isolate between two electric submersible pump (ESP) assemblies in a redundant ESP system. While hydraulic pistons, setting devices, slips, and other actuatable components can be used to accommodate such isolation in a redundant ESP system, these components are relatively complex and require the casing or other tubular in which they are installed to have a sufficiently large diameter. Larger diameter casings require increased time and material, and therefore cost, to complete, and there is consequently an ever-present desire in the industry to reduce the radial dimensions of boreholes and completion equipment. As a result, alternative designs for pack-off devices are always well received in the art, particularly those alternatives that can be effectively deployed in boreholes of smaller dimensions. 
     SUMMARY 
     A pack-off device, including a body having a first feedthrough and a second feedthrough formed therein; a projection extending from the body and operatively arranged to engage a restriction of an adjacent structure; and at least one seal element arranged with the body for sealing the device against the adjacent structure when the projection is engaged with the restriction. 
     A method of arranging and operating a completion system, including arranging a first component of the completion system through a first feedthrough of a pack-off device and a second component of the completion system through a second feedthrough of the pack-off device; landing the pack-off device at a restriction due to a projection of the device dimensionally overlapping the restriction; engaging one or more seal elements of the device with the restriction; and isolating areas on opposite sides of the device from each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  is a cross-sectional view of a pack-off device according to one embodiment disclosed herein; 
         FIG. 2  is a cross-sectional view of the pack-off device of  FIG. 1  taken generally along line  2 - 2 ; and 
         FIG. 3  schematically illustrates a redundant electric submersible pump system including the device of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     Referring now to  FIG. 1 , a system  10  is shown including a packer or pack-off device  12 . The device  12  includes a body  14  having a primary passageway or feedthrough  16  and at least one auxiliary feedthrough  18  formed therein. The primary feedthrough  16  is operatively arranged to receive a tubular string  20 , which in one embodiment, is or is included with a production string. The second feedthrough  18  is operatively arranged to receive a control line, electric cable, power lead, wire, fiber, conductor, etc., generally represented as a cable  22 . In one embodiment, feedthroughs  16  and  18  are complementarily threaded with respect to the tubular string  20  and/or the cable  22  for securing the string  20  and/or the cable  22  and the body  14  together. In the case of the cable  22  which has a diameter or dimension smaller than that of the feedthrough  18 , or  FIG. 1 , a sealing cap  24  or other member could be secured in or inserted into the feedthrough  18  (e.g., via threads, force fit, etc.) for sealing opposite sides of the feedthrough from each other. 
     The terms primary and auxiliary with respect to the feedthroughs  16  and  18  are used for convenience only in discussing the illustrated embodiment and it is to be appreciated that the feedthroughs  16  and  18  could take any relative size or orientation. It is to be further appreciated that multiple ones of the primary or auxiliary feedthroughs  16  and  18  could be included in the body  14  of the device  12 . For example, as shown in cross-section in  FIG. 2 , the body  14  includes three of the auxiliary feedthroughs  18  for enabling a greater number of electric cables, power leads, or other conductors, lines, etc., to extend through the device  12 . In order to maximize flow area while minimizing overall dimensions of the device  12  (therefore also minimizing the necessary inner diameter or dimensions of the structure  28 ), the primary feedthrough  16  can be positioned eccentrically, with the relatively smaller auxiliary feedthroughs  18  arranged at least partially circumferentially about the feedthrough  16  in an arcuate pattern, as illustrated in  FIG. 2 . 
     A projection  26  extends from the body  14 , radially in the illustrated embodiment, for enabling the body  14  to locate at a restriction  28  in a structure  30 . That is, the projection  26  and the restriction  28  radially overlap so that the restriction  28  will block travel of the device  12  and cause the body  14  to land at the restriction  28 . In one embodiment the restriction  28  is a polished nipple bore or similar structure having a complementarily formed profile or surface that engages with or against the projection  26  for locating the device  12  within the structure  30 . The structure  30  is, for example, a casing, liner, shroud, string, tubular, etc., and is, e.g., run into a borehole while completing the borehole. The device  12  includes one or more seal elements  32  arranged to seal the body  14  within the restriction  28  when the body  14  is located due to the projection  26  landing at the restriction  28 . The seal elements  32  are, e.g., elastomeric rings or any other known seal member for enabling isolation between the areas within the structure  30  on opposite sides of the device  12 . Advantageously, since the device  12  will be located at the restriction  28  (i.e., due to the projection  26  landing at the restriction  28 ) and the dimensions of the restriction  28  are known (e.g., machined within certain tolerances), the seal elements  32  can be accordingly configured (in shape, size, material, etc.) to provide a predictably reliable seal against the restriction  28 , while occupying a relatively small radial dimension and without the need for any moving components such as slips, pistons, setting assemblies, etc. 
     In the exemplary embodiment shown in  FIG. 3 , the device  12  is located between a pair of electric submersible pump (ESP) assemblies  34  and  36 . The ESP assemblies  34  and  36  may include suitable motors, pumps, intakes, seals, cross-overs, etc., that are generally known in the art. The generically illustrated structure  30  in  FIG. 1  is represented with more specificity in  FIG. 2  by a shroud  38  that surrounds the assemblies  34  and  36 . For example, the shroud  38  is anchored in an outer structure  40 , e.g., a cased or lined borehole by a shroud hanger  42 . It is to be appreciated that in other embodiments, a shroud may not be included, the device  12  may be directly located in a cased or lined borehole, or some other tubular structure, etc. 
     While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.