Abstract:
An apparatus that is usable with a subterranean well includes a latch and an engagement mechanism. The latch is adapted to form a releasable connection between a first conduit section and a second conduit section in response to engagement of an actuator of the latch and maintain a first distance between an end of the first conduit section and an end of the second conduit section. The engagement mechanism is adapted to continuously engage the actuator to cause the latch to connect the first conduit section and the second conduit section despite the movement of the engagement mechanism between a first position and a second position. The second distance between the first position and the second position is greater than the first distance.

Description:
BACKGROUND  
         [0001]    The invention generally relates to a system to connect conduit sections in a subterranean well, and more particularly, the invention relates to a system to form a releasable connection between conduit sections and to limit movement of the conduit sections with respect to each other when connected together.  
           [0002]    Several different conduit members typically are present in a subterranean well for purposes of communicating well fluids, hydraulic fluids, etc. Some of these conduit members may be formed from connected conduit sections. More particularly, one end of each conduit section may form a female connector, and the other end of the conduit section may form a male connector. The female connector of each conduit section mates with the male connector of an adjacent conduit section so that the conduit sections may be connected in an end-to-end fashion to form the tubular member. An example of a connection between two such conduit sections is depicted in FIG. 1.  
           [0003]    Referring to FIG. 1, as an example, the connection may be formed from a female connector assembly  10  (that is attached to the upper end  21  of a lower conduit section  12 ) and the lower end  20  (forming a male connector) of an upper  14  conduit section. The connection is established by lowering the upper conduit section  14  downhole into the wellbore so that the lower end  20  of the upper conduit section  14  enters, or “stabs,” an upper opening  19  of the female assembly  10 .  
           [0004]    As depicted in FIG. 1, for purposes of guiding the lower end  20  of the upper conduit section  14  into the female connector assembly  10 , the assembly  10  may include such features as an inclined surface  11  (of an upper housing section  17  of the assembly  10 ) that is slanted toward the opening  19 . Furthermore, for purposes of forming a seal between the upper  12  and lower  14  conduit sections, the female connector assembly  10  may include a seal assembly  18  that is contained within a middle section  15  of the assembly  10 . The seal assembly  18  may include a stack of annular seals that reside between the exterior surface of the upper conduit section  14  and the interior surface of the middle section  15  of the female connector assembly  10 . The seal between the conduit sections  12  and  14  exists only for the condition in which a gap d between the lower end  20  of the upper conduit section  14  and the upper end  21  of the lower conduit section  12  remains smaller than a specified distance (0.0250 inches, as an example). For a gap d greater than this specified distance, the integrity of the seal that is formed between the conduit sections  12  and  14  may be affected.  
           [0005]    In a conventional well system, the conduit sections  12  and  14  may form part of a hydraulic conduit string that is used, as its name implies, for purposes communicating hydraulic fluid downhole. This hydraulic conduit string may be located inside or outside of a production tubing string (not shown) of the well. Thus, each conduit section  12 , 14  may be associated with and located inside or outside of a production tubing section (not shown). As a more specific example, the lower conduit section  12  may be located inside or outside of a lower production tubing section, and the upper conduit section  14  may be located inside or outside of an upper production tubing section. Adjacent production tubing sections (that form part of the production tubing string) may be connected together concurrently with the connection of the associated adjacent conduit sections (that form part of the hydraulic conduit string).  
           [0006]    A potential difficulty with the above-described system is the criteria that for establishing an acceptable connection between the production tubing sections may be significantly different than the criteria for establishing an acceptable connection between the conduit sections  12  and  14 . More specifically, the acceptable gap between adjacent ends of the production tubing sections may be significantly larger than the acceptable gap between the upper  20  and lower  21  ends of the conduit sections  12  and  14 . By way of example, it may be acceptable for a gap of 0.75 inches or less (as an example, for comparison) to exist between the lower end of an upper production tubing section and the upper end of an adjacent lower production tubing section. This acceptable gap between production tubing sections may be significantly larger than the acceptable gap of 0.025 inches or less (as an example, for comparison) between the upper  20  and lower  21  ends of the conduit sections  12  and  14 . Due to forces that are exerted on the conduit sections  12  and  14  by the production tubing sections, a movement between the production tubing sections may cause a relatively large movement (i.e., a movement greater than 0.025 inches, for example) between the adjacent ends of the conduit sections  12  and  14  and thus, may impair the seal between the conduit sections  12  and  14 .  
           [0007]    Thus, there is a continuing need for a better system for connecting tubular sections in a subterranean well.  
         SUMMARY  
         [0008]    In an embodiment of the invention, an apparatus that is usable with a subterranean well includes a latch and an engagement mechanism. The latch is adapted to form a releasable connection between a first conduit section and a second conduit section in response to engagement of an actuator of the latch and maintain a first distance between an end of the first conduit section and an end of the second conduit section. The engagement mechanism is adapted to continuously engage the actuator to cause the latch to connect the first conduit section and the second conduit section despite the movement of the engagement mechanism between a first position and a second position. The second distance between the first position and the second position is greater than the first distance.  
           [0009]    Advantages and other features of the invention will become apparent from the following drawing, description and claims.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0010]    [0010]FIG. 1 is a schematic diagram of a connection between conduit sections of the prior art.  
         [0011]    [0011]FIG. 2 is a schematic diagram of a system for connecting conduit sections according to an embodiment of the invention.  
         [0012]    [0012]FIG. 3 is a schematic diagram of the system of FIG. 2 after connection of the conduit sections but before engagement of a latch to secure the connection between the conduit sections.  
         [0013]    [0013]FIG. 4 is a schematic diagram of the system of FIG. 2 depicting engagement of the latch to secure the conduit sections together.  
         [0014]    [0014]FIG. 5 is a top view of a plate of the system according to an embodiment of the invention.  
         [0015]    [0015]FIG. 6 is a cross-sectional view taken along line  6 - 6  of FIG. 2.  
         [0016]    [0016]FIG. 7 is a schematic diagram of a portion of the sleeve and upper production tubing section according to another embodiment of the invention.  
         [0017]    [0017]FIG. 8 is a cross-sectional view taken along line  8 - 8  of FIG. 7. 
     
    
     DETAILED DESCRIPTION  
       [0018]    Referring to FIG. 2, an embodiment  30  of a system to releasably connect conduit sections together in a subterranean well in accordance with the invention includes a latch, such as a latch assembly  70 . More specifically, the latch assembly  70  may be operated, as described below, to releasably secure lower conduit sections  94  (conduit sections  94   a  and  94   b , depicted as examples) to corresponding upper conduit sections  45  (conduit sections  45   a  and  45   b , depicted as examples) for purposes of creating portions of conduit strings (two hydraulic conduits, for example) within the well. In operation, the latch assembly  70  may be placed in an engaged state, a state in which the latch assembly  70  secures the conduit sections  45  and  94  together. The latch assembly  70  may also be placed in a disengaged state, a state in which the latch assembly  70  releases the conduit sections  45  and  94  so that the upper conduit sections  45  may be retrieved uphole and be separated from the lower conduit sections  94 .  
         [0019]    As a more specific example, when the latch assembly  70  is engaged, the assembly  70  sealably and mechanically connects the upper conduit section  45   a  to the lower conduit section  94   a , and sealably and mechanically connects the upper conduit section  45   b  to the lower conduit section  94   b . As described below, in this engaged state, the assembly  70  maintains the sealed connections between the upper  45  and lower  94  conduit sections by limiting the relative movement between the upper  45  and lower  94  conduit sections.  
         [0020]    For purposes of placing the latch assembly  70  in its engaged state, the system  30  includes an engagement mechanism, such as a sleeve  40  (in accordance with some embodiments of the invention), that is generally coaxial with the longitudinal axis of the latch assembly  70 . As described further below, after the lower end  50  of each upper conduit section  45  has been inserted into corresponding passageways of the latch  70 , the lower end of the sleeve  40  slides over the outer surface of the latch assembly  70  to engage an actuator (described below) of the assembly  70  to place the assembly  70  in the engaged state.  
         [0021]    In some embodiments of the invention, the upper conduit sections  45  may extend along the outside of an upper production tubing section  96 , and the lower conduit sections  94  may extend along the outside of a lower production tubing section  97 . More specifically, the upper conduit sections  45  may be slidably connected to the sleeve  40 , and the sleeve  40  may, in turn, be secured to the outside of the upper production tubing  96 . The upper conduit sections  45  may be located inside the sleeve  40  in some embodiments of the invention. More specifically, referring also to FIG. 6, in some embodiments of the invention, the sleeve  40  may be eccentric with respect to the upper production tubing section  96 . As shown in FIGS. 2 and 6 the upper conduit sections  45  have longitudinal axes that are generally parallel with the longitudinal axis of the upper production tubing section  96 .  
         [0022]    It is noted that in other embodiments of the invention, the orientation of the sleeve  40  with respect to the upper production tubing section  96  may be different from that shown in FIGS. 2 and 6. For example, in some embodiments of the invention, the sleeve  40  may be located inside the upper production tubing section  96 . Furthermore, in some embodiments of the invention, the sleeve  40  may be concentric with the production tubing section  96  so that, depending on the particular embodiment of the invention, one of the upper production tubing section  96  and the sleeve  40  circumscribes the other. Other variations are possible.  
         [0023]    Referring to FIG. 2, in some embodiments of the invention, the upper conduit sections  45  are located inside the sleeve  40  so that each upper conduit section  45  extends through a corresponding opening  39  (see also FIG. 5) in an inner plate  43  of the sleeve  40 . The inner plate  43  is shown for the embodiment in which the sleeve  40  is eccentric to and located on the outside of the upper production tubing section  96 . Each opening  39  (FIG. 5) of the inner plate  43  is sized to permit the conduit section  45  that extends through the opening to generally slide with respect to the sleeve  40 . However, the downward movement of the upper conduit sections  45  relative to the sleeve  40  is limited by annular shoulders  46  of the upper conduits  45 . More particularly, each upper conduit section  45  has an annular shoulder  46  that has an external diameter that is too large for the opening  39  of the plate  43  through which the upper conduit section  45  otherwise slides. Therefore, the upper conduit sections  45  may slide downwardly with respect to the sleeve  40  (and upper production tubing section  96  to which the sleeve  40  is secured) to a certain extent, with the length of travel of the upper conduit sections  45  being limited by the interactions of the shoulders  46  and plate  43 . Therefore, due to the above-described arrangement, the sleeve  40 , upper production tubing section  96  and upper conduit sections  45  may be lowered downhole together as a unit for purposes of forming connections with a lower production tubing section  97  and the lower conduit section  94 . Similarly, for purposes of disconnecting the production tubing sections  96  and  97  and disconnecting the conduit sections  45  and  94 , the sleeve, upper production section  96  and upper conduit sections  45  may be retrieved uphole together as a unit.  
         [0024]    The ability of the upper conduit sections  45  to slide with respect to the sleeve  40  and upper production tubing section  96  permits 1. the upper conduit sections  45  to engage the latch assembly  70  (as described below) for purposes of forming connections and  2 . once the conduit sections are connected together permits the upper production tubing section  96  to slide with respect to the upper conduit sections  45 . This latter feature permits a greater degree of up and down travel between the upper production tubing section  96  and the lower production tubing section  97  relative to the degree of up and down travel that the latch assembly  70  permits between the upper  45  and lower  94  conduit sections.  
         [0025]    The latch assembly  70  is secured to the lower production tubing section  97  and may be located on the outside of the production tubing section  97 , in some embodiments of the invention. As described below, in some embodiments of the invention, the assembly including the upper production tubing section  96 , sleeve  40  and upper conduit sections  45  is lowered downhole until the upper conduit sections  45  slide into the latch assembly  70 . Referring also to FIG. 3, in this downward descent, when the upper conduit sections  45  stop moving relative to the upper production tubing section  96  and the sleeve  40 , the section  96  and sleeve  40  move downwardly with respect to the upper conduit sections  45 . Eventually, the sleeve  40  engages the actuator of the latch assembly  70  (to lock the upper conduit sections  45  in the latch assembly  70 ) and the upper production tubing section  96  mates with the lower production tubing section  97 , as depicted in FIG. 4.  
         [0026]    Referring to FIG. 4, when the actuator of the latch assembly  70  is engaged to secure the upper  45  and lower  94  conduit sections together a gap exists between the lower surfaces of the annular shoulders  46  and the plate  43 . This gap, in turn, permits the upper production tubing section  96  to slide with respect to the lower production tubing section  97  and also permits the upper production tubing section  96  to slide with respect to the upper conduit sections  45 . This ability for the upper production tubing section  96  to slide relative to the upper conduit sections  45  prevents the upper production tubing section  96  from exerting a hard force on the latch assembly  70  that may otherwise break the latch assembly  70 .  
         [0027]    The sliding of the upper production tubing section  96  with respect to the upper conduit sections  45 , however, may produce frictional forces that may tend to force the conduit sections  45  and  94  (when connected) apart. However, as described below, the connection that is formed by the latch assembly  70  limits the degree of movement between the upper  45  and lower  94  conduit sections to preserve seal integrity between these sections  45  and  94 . As a more specific example, in some embodiments of the invention, the connection that is formed by latch assembly  70  ensures that the lower end  50  of each upper conduit section  45  does not move beyond 0.025 inches from the upper end  98  of the associated lower conduit section  94 . Other travel limits are possible.  
         [0028]    In some embodiments of the invention, the upper  96  and lower  97  production tubing sections may form portions of a production tubing that extends into the well. In some embodiments of the invention, the upper  45  and lower  94  conduit sections may form portions of two hydraulic conduit strings that extend into the well inside or outside of the production tubing string. As a more specific example, in some embodiments of the invention, one or both hydraulic conduit strings may be used for purposes of pumping an optical fiber downhole via fluid drag, as described further in U.S. Reissue Pat. No. 37,283.  
         [0029]    Although only one latch assembly  70  is depicted in the figures, it is understood that one latch assembly may be located at the union of each conduit section in the assembled hydraulic conduit string. Furthermore, although portions of two hydraulic conduit strings are depicted in the figures, it is understood that a single hydraulic conduit string or more than two hydraulic conduit strings may be installed downhole via the latch assembly  70  at each conduit section connection.  
         [0030]    The two hydraulic conduit string arrangement that is depicted in FIG. 2 may be used for purposes of establishing a U-shaped conduit in which the lower ends of the hydraulic conduit strings are connected together (not shown in FIG. 2) so that fluid may be pumped downhole through one hydraulic conduit string and return uphole through the other hydraulic conduit string. Such an arrangement is advantageous for pumping an optical fiber downhole via fluid drag, as described further in U.S. Reissue Pat. No. 37,283.  
         [0031]    The optical fibers referred to herein may be used for purposes of forming a distributed temperature measurement (DTS) system and/or a Fiber Bragg Grating temperature measurement system, as described in U.S. patent application Ser. No. 10/317,556; and U.S. Pat. Nos. 5,798,521 and 6,246,048, as just a few examples.  
         [0032]    In some embodiments, of the invention, the lower end of the upper production tubing section  96  may have a male connector (not shown) that stabs a female connector in the upper end of the lower production tubing section  96 . The upper production tubing section  96  may have a tendency to significantly move (relating to movement between an upper conduit section  45  and a lower conduit section  94  to which the section  45  is connected) with respect to the lower production tubing section  97  after the two sections  96  and  97  are joined together. Furthermore, because, in some embodiments of the invention, the sleeve  40  is attached to or is part of the upper production tubing section  96 , longitudinal movement of the upper production tubing section  96  may cause a corresponding longitudinal movement in the sleeve  40 .  
         [0033]    As a more specific example, the upper production tubing section  96  may be part of a seal bore so that the upper production tubing  96  (and thus the sleeve  40 ) may significantly move with respect to the lower production tubing  97  after the production tubing sections  96  and  97  mate and the conduit sections  45  and  94  mate. As another example, the upper production tubing  96  may be coiled conduit that has sufficient slack in the wellbore to permit the upper production tubing  96  to significantly move within the wellbore. Other variations are possible. The production tubing sections  96  and  97  maintain their connections even with this movement. As described above, the movement of the upper production section  96  tends to exert forces on the upper conduit sections  45 , and these forces may be directed to separating the upper conduit sections  45  from the lower conduit sections  94 .  
         [0034]    However, regardless of the degree in which the production tubing sections  96  and  97  move relative to each other, the latch assembly  70 , in its engaged state, limits movement of the upper  45  and lower  94  hydraulic conduit sections, relative to each other.  
         [0035]    In some embodiments of the invention, the latch assembly  70  is generally attached to the upper ends of the lower conduit sections  94 . The latch assembly  70  may be formed from a generally circularly cylindrical housing  73  that is coaxial with the longitudinal axis of the well. The housing includes a generally dome-shaped top surface  71  that includes two openings  72 , each of which receives the lower end  50  of one of the upper conduit sections  45 . Each opening  72  provides an entry port into an associated longitudinal passageway  74  of the latch assembly  70 . Thus, each longitudinal passageway  74  receives the lower end  50  of one of the upper conduit sections  45  when the upper sections  45  are lowered into the latch assembly  70 . As depicted in FIG. 2, for each longitudinal passageway  74 , the latch assembly  70  includes at least one associated radial passageway  80  that intersects the passageway  74 . Each radial passageway  80 , in turn, provides a path for an associated actuator, or dog  78 , to move inside the longitudinal passageway  74 .  
         [0036]    When the latch  70  is not engaged (FIG. 2 or  3 ), each dog  78  is located entirely outside of the passageway  74  so that in this position, an exterior surface of the dog  78  protrudes slightly beyond the general outer cylindrical surface of the housing  73 . Due to the absence of each dog  78  from its associated passageway  74 , the passageway  74  is unobstructed for purposes of allowing the lower end  50  of the upper conduit section  45  to pass through the passageway  74  into an associated female connector  90  (female connectors  90   a  and  90   b , depicted as examples), described below.  
         [0037]    Each female connector  90  guides the lower end  50  of the upper conduit section  45  into an associated lower conduit section  94 . In some embodiments of the invention, the female connectors  90  may be part of the latch assembly  70 . In some embodiments of the invention, each passageway  74  is coaxial with a central passageway  91  of the associated female connector  90 . Each female connector  90 , in turn, is connected to the upper end  98  of the associated lower conduit section  94 . The female assembly  90  receives the lower end  50  of the upper conduit section  45  and includes seals that closely circumscribe the lower end  50  to form a sealed connection between the upper conduit section  45  and the lower conduit section  90 . When the two conduit sections  45  and  94  meet inside the female connector  90 , the upper  45  and lower  94  conduit sections may move apart by a relatively small distance, and the latch assembly  70  controls this distance to ensure that the gap between the matting ends of the upper  45  and lower  94  conduit sections does not exceed a predetermined maximum distance (a 0.025 inch maximum distance, for example) apart. Regulating this gap to ensure the gap does not exceed a certain distance maintains the integrity of the sealed connection between these conduit sections. In embodiments of the invention in which an optical fiber is pumped through the conduit that is formed the conduit sections  45  and  94 , at least one of the reasons to confine the gap to a maximum distance and preserve seal integrity is to ensure proper pumping of the optical fiber.  
         [0038]    Because the conduit sections  45  and  94  are slidably connected to production tubing sections, relative movement of these production tubing sections may impart separation forces on the conduit sections  12  and  14 , and these forces may move the hydraulic sections farther apart, if not for the securement of the conduit sections by the latch assembly  70 . More specifically, it may be acceptable for the production tubing sections  96  and  97  to move a relatively larger distance apart (0.075 inches, for example), as compared to the acceptable distance by which the ends  50  and  98  of the conduit sections  45  and  94  may be separated. Therefore, relative movement of the production tubing sections  96  and  97  with respect to each other may, if not for the features of the latch assembly  70 , cause an undesirable separation between the conduit sections  45  and  94 .  
         [0039]    To limit any potential travel, or separations between the conduit sections  45  and  94 , in some embodiments of the invention, the lower end  50  of the upper conduit section  45  includes a profile, or notch  51 , that is engaged by one or more dogs  78  of the latch assembly  70  when the lower end  50  of the upper conduit section  45  is lowered into the corresponding passageway  91  of the female connector  90  and the latch assembly  70  is engaged, as depicted in FIG. 3.  
         [0040]    [0040]FIG. 3 generally depicts the insertion of the lower ends of the upper conduit sections  45  into the female connectors  90  before the mating of the production tubing sections  96  and 9 O 7 . As shown, when full insertion occurs, each notch  51  is located in a position such that a corresponding dog  78  is in a radially outward position from the notch  51 . As can be appreciated from FIG. 3, in some embodiments of the invention, the profile of the interior surface of each dog  78  generally conforms to the profile of the notch  51 .  
         [0041]    The dogs  78  are each biased to remain outside of the passageway  74 , and thus, the dogs  78  do not engage the notches  51  upon mere insertion of the upper conduit sections  45  into the female connectors  90 . However, as depicted in FIG. 3, the sleeve  40  includes an inclined lower section  41  that has a diameter that increases with its downhole position. Thus, as can be seen from FIG. 3, as the sleeve  40  moves in a downward direction, the inner surface of the inclined section  41  exerts a radially inwardly directed force on each dog  78  to force each dog  78  inside the corresponding notch  51 . The engagement of the dogs  78  in the notches  51 , in turn, locks the upper conduit sections  45  in place with respect to the latch assembly  70  and the lower conduit section  94 .  
         [0042]    Referring to FIG. 4, at its lowest point of travel, a radially extending flange  42  of the sleeve  40  contacts a radially extending flange  95  of the latch assembly  70 . At this point, the inclined section  41  of the sleeve  40  has transitioned past the dogs  78  so that the sleeve  40  now closely circumscribes the dogs  78  to force the dogs  78  fully into the notches  51  to engage the latch assembly  70 .  
         [0043]    As depicted in FIG. 4, to release the dogs from the notches, the sleeve  40  must move by a distance D, a distance that is much greater than the acceptable distance for the upper production tubing section  96  to move with respect to the lower production tubing section  97  to maintain a proper connection between. Due to this arrangement, the latch assembly  70  accommodates a wide variation of movement between the upper and lower production tubing sections while maintaining a locked connection between the upper  45  and lower  94  hydraulic conduit sections.  
         [0044]    To disengage the latch assembly  70 , an upward force is exerted on the upper production tubing section  96  from the surface of the well, and the production tubing section  96  is moved upwardly to raise the sleeve  40  also in an upwardly direction. This state is generally depicted in FIG. 3. Eventually, the sleeve  40  is raised past the distance D to allow the dogs  78  to radially expand to release the grip of each dog  78  on the corresponding notch  51 . The sleeve  40  continues to travel in an upward direction (due to the upper travel of the production tubing section  96 ), and at some point, the plate  43  engages the annular shoulders  46  to lift the bottom ends  50  of the upper conduit sections  45  out of the latch assembly  70 , as depicted in FIG. 2.  
         [0045]    Other variations are within the scope of the following claims. For example, in some embodiments of the invention, the hydraulic conduits, latch assembly  70  and sleeve  40  may be located inside the production tubing. As another example, in some embodiments of the invention, the locking of the latch assembly may be performed in response to power that is supplied by an external power source, instead of occurring in response to a mechanical action.  
         [0046]    As another example of another embodiment of the invention, FIG. 7 depicts an arrangement  300  in which an upper production tubing section  396  replaces the upper production tubing section  96  and a sleeve  340  replaces the sleeve  40 . The sleeve  340  is concentric with and circumscribes the upper production tubing section  396 . This arrangement  300  also includes an annular plate  343  that radially extends between the exterior of the upper production tubing section  396  and the interior of the sleeve  340 . In some embodiments of the invention, the annular plate  343  may be secured to both the sleeve  340  and the upper production tubing section  396  to secure these entities together. Referring also to FIG. 8, the annular plate  343  includes openings  339  to receive the upper conduit sections  45  (not shown in FIGS. 7 and 8). Similar to the openings  39  of the plate  43 , the openings  339  of the plate  343  are sized to catch the shoulders  46  of the upper conduit sections  45  to limit downward travel of the upper conduit sections  45  relative to the sleeve  340  and upper production tubing section  396 .  
         [0047]    Although orientational terms such as “up,” “down,” etc. may have been used for purposes of simplifying the preceding discussion, it is understood that other orientations of the system  30  are possible. For example, although a vertical well is depicted in the drawings, it is understood that the system  30  may be used in a lateral wellbore, for example. Other variations are possible.  
         [0048]    While the present invention has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.