Abstract:
A hydraulic coupler for providing fluid communication between adjacent members that includes a two way check valve formed from a double headed poppet set in a hollow cylinder with corrugated bellows like walls. Contoured bores are provided in the cylinder ends and the poppet heads are profiled to match the contour of the bores. When the heads are seated in the bores they form a sealing surface to block fluid from flowing through the coupler. Compressively preloading the cylinder before assembly provides a sealing force between the heads and the bores. Axially compressing the cylinder with respect to the poppet unseats the heads from the bores to form a flow path through the coupler.

Description:
1. FIELD OF THE INVENTION 
       [0001]    This invention relates in general to production of oil and gas wells, and in particular to a hydraulic coupler that is bi-directionally self sealing. 
       2. DESCRIPTION OF RELATED ART 
       [0002]    Actuators for valves and other components in subsea wellheads and for subsea running tools, may be powered by hydraulic fluid delivered from a pressurized hydraulic fluid source. The fluid is typically delivered through a hydraulic circuit running across separate wellhead components. Hydraulic couplers provide a seal where the circuit crosses from one component to another. Many current subsea hydraulic couplings include elastomeric seals. However elastomers can degrade over time and in response to their operating environment and lose their sealing capability. Some existing couplings employ metal-to-metal seals as primary seal elements. Known metal seal hydraulic couplings are complex in design and include many parts. Additionally, at least some of the parts are fragile, such as metal o-rings or metal face seals. These types of seals are easily misaligned; require a precise connection and/or disconnection angle, and subject to damage from debris. The fragile nature of the seals require small manufacturing tolerances that substantially increase cost. 
       SUMMARY OF INVENTION 
       [0003]    Disclosed herein is a hydraulic coupler for use in a subsea wellhead that communicates fluid between a first and a second member. In one embodiment the coupler includes an axially compressible and resilient corrugated tubular, a lower base connected to a lower end of the tubular having a side for pressure communication with a passage formed in the second member, a bore extending through the lower base, an upper base connected to an upper end of the tubular having an upper side in pressure communication with a region ambient to the second member, a bore extending through the upper base, an elongated shaft coaxially disposed within the tubular, on an end of the shaft, an upper head seated against the upper base and defining a pressure seal between the upper base bore and the region ambient to the second member, and on an end of the shaft opposite the upper head, a lower head seated against the lower base and defining a pressure seal between the lower base bore and the passage foamed in the second member. The coupler can also include an annular retainer circumscribing the tubular and adapted to be threadingly secured to the second member, so that the lower base is wedged between the retainer and the second member. A void may be included between the tubular and the retainer adapted to be in pressure communication with the region ambient the second member. The tubular can be an annular bellows member. Also optionally included is a male stab mountable on the first member having a surface that engages with the upper base and circumscribes the upper head, so that contacting the upper base with the male stab compresses the tubular and moves the upper base relative to the upper head, thereby breaching the pressure seal between the outer head and bore in the upper base. 
         [0004]    Another embodiment described herein is a hydraulic coupler for use in communicating fluid between members used in hydrocarbon production subsea. The hydraulic coupler can include first and second subsea well members, each having a hydraulic fluid port, a hollow tubular mounted to the first member and having a resilient corrugated side wall and a longitudinal axis, the interior of the tubular or sleeve being in fluid communication with the hydraulic fluid port in the second member, an upper seat in an upper end of the sleeve and facing upward, a lower seat in a lower end of the sleeve and facing downward, a poppet member coaxially disposed in the sleeve having an upper end and a lower end, so that when the sleeve is in a pre-loaded axially compressed configuration, the upper end is in sealing engagement with the upper seat and the lower end is in sealing engagement with the lower seat. 
         [0005]    Further disclosed is a method of hydraulically coupling members used in subsea hydrocarbon production. In an embodiment the method includes providing on a member used in subsea hydrocarbon production, a resilient and axially compressible hollow tubular or sleeve having seats at its upper and lower ends, a poppet member coaxially disposed in the sleeve with ends extending outside the ends of the sleeve and in sealing engagement with the seats, so that an end of the sleeve is in pressure communication with a region ambient to the member and the opposite end of the sleeve is in pressure communication with a flow line in the member, compressing the sleeve by applying a force to an end of the sleeve thereby breaching the sealing engagement with the poppet at the end of the sleeve where the force is being applied, pushing the poppet to breach the sealing engagement between the poppet and the other end of the sleeve, flowing fluid between the poppet and an end of the sleeve, through the cylinder, and out the other end of the sleeve, and removing the force compressing the sleeve so that the resilient sleeve returns to its configuration for sealing engagement between the sleeve ends and poppet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a schematical sectional view of a hydraulic coupler between a running tool and a tubing hanger. 
           [0007]      FIG. 2  depicts in a side sectional view an embodiment of a hydraulic coupler in accordance with the present disclosure. 
           [0008]      FIG. 3  illustrates a side sectional view of the hydraulic coupler of  FIG. 2  in an engaged configuration. 
           [0009]      FIG. 4  depicts in a side partial sectional view a force schematic of a simplified embodiment of a hydraulic coupler. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]    The apparatus and method of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. This subject of the present disclosure may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. For the convenience in referring to the accompanying figures, directional twins are used for reference and illustration only. For example, the directional terms such as “upper”, “lower”, “above”, “below”, and the like are being used to illustrate a relational location. 
         [0011]    It is to be understood that the subject of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments of the subject disclosure and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the subject disclosure is therefore to be limited only by the scope of the appended claims. 
         [0012]    Shown schematically in a side partial sectional view in  FIG. 1  is an example of a hydraulic coupler for use in coupling hydraulic lines between a running tool  10  and tubing hanger  12 . In this example, a running tool  10  is coupled to a tubing hanger  12  for its deployment within a wellhead housing or production tree (not shown). It can also set a seal or packoff between tubing hanger  12  and the tree. The running tool  10  is shown suspended from a typical drill pipe  14  running string and includes passages  20  each connecting to a hydraulic coupler  22 , shown disposed between both the running tool  10  and tubing hanger  12 . The passages connect on their respective upper ends to umbilicals (not shown) that deliver fluid to the passages  20 . As noted above, the hydraulic couplers  22  can provide a sealed way of communicating hydraulic fluid across an interface between two adjacent components. Shown depending from each hydraulic coupler  22  is a fluid passage  24  for distributing the pressurized hydraulic fluid to components (not shown) that may be actuated by selectively directing hydraulic fluid to that component. 
         [0013]      FIG. 2  provides an example of a hydraulic coupler shown in more detail. A side sectional view is shown of a running tool  30  is shown in  FIG. 2  mating with a tubing hanger  32  and a detail of a hydraulic coupler  34 . As will be described in more detail below, when the tool  30  and hanger  32  are engaged the coupler  34  provides fluid flow therebetween. When the tool  30  and hanger  32  are not engaged, the coupler  34  self seals. In the embodiment of  FIG. 2 , the hydraulic coupler  34  includes a male stab  36  shown as a cylindrical member depending down from the running tool  30 . A bore  38  is shown formed in the stab  36  that extends along the stab  36  axis. The bore  38  is in fluid communication with a fluid lead line  40  within the running tool  30 . The bore  38  extends a portion within the male stab  36 ; distribution lines  42  project obliquely away from the stab  36  axis to a cavity  43  provided on the stab  36  lower face. Through the bore  38  and distribution lines  42 , the cavity  43  is in fluid communication with the passage  40 . 
         [0014]    The hydraulic coupler  34  also includes a cylindrical female portion  44  that is substantially coaxial with the male stab  36  and shown disposed within a pocket  46  in the tubing hanger  32  upper portion. The female portion  44  includes an elongated poppet  48  oriented substantially along the axis of the female portion  44 . The poppet  48 , shown formed from an elongated shaft  50 , includes an upper poppet head  51  on an end shown facing the cavity  43  in the male stab  36 . A lower poppet head  52  is on the shaft  50  and facing the bottom end of the pocket  46 . Each poppet head  51 ,  52  has a generally frusto-conical cross section and a largely planar surface provided on opposing ends and facing opposing ends of the female portion  44 . 
         [0015]    Circumscribing the poppet  48  is an annular sleeve  54 . A disc-like upper base  56  forms the upper end of the sleeve  54  shown disposed proximate the male stab  36 . A bore  57  is provided through the upper base  56  that is contoured in the side of the bore  57  facing the cavity  43 . The contour in the bore  57  is formed to match the frusto-conical shape of the upper poppet head  51 . Moreover, the interface between the upper poppet head  51  and bore  57  when in contact forms a sealing surface. Optional embodiments exist where the poppet head  51  has a planar lower surface that rests on the outer surface of the base  56 . 
         [0016]    Similarly, on the end of the sleeve  54  proximate the bottom of the pocket  46  is a lower base  58  with a bore  59  formed therethrough and contoured on the side of the bore  59  facing the bottom of the pocket  46 . Similar to the bore  57  on the upper base  56 , the bore  59  is contoured to mate with the inclined surface on the lower poppet head  52  and when engaged form a sealing surface. The portion of the sleeve  54  between the upper and lower bases  56 ,  58  is an annular bellows  60  with an undulating surface and its upper and lower ends connecting respectively to the upper and lower bases  56 ,  58 . Bellows  60  is resilient and in an embodiment formed wholly or partially from steel. As will be described in more detail below, the female portion  44  of the hydraulic coupling  34  is self sealing in both directions across its axis by setting the upper poppet head  51  diameter D 1  greater than the bellows  60  diameter D 3  where it attaches with the lower base  58  (see  FIG. 4 ). 
         [0017]    An annular retainer  62  is shown circumscribing the sleeve  54 . The annular retainer  62  is a tube-like member having an inner diameter exceeding the diameter of the upper head  56  and the maximum diameter of the bellows  60 . However, the lower base  58  outer diameter exceeds the retainer  62  inner diameter so that the retainer  62  rests on the lower base  58  upper surface when both are set within the pocket  46 . Threads  64  are shown formed along corresponding surfaces of the retainer  62  outer surface and pocket  46  inner surface. Engaging these threads  64  secures the retainer  62  within the pocket  46  and wedges the lower base  58  between the retainer  62  and bottom of the pocket  46 . Accordingly, the entire female portion  44  is anchored within the pocket  46  by the retainer  62 . In the embodiment of  FIG. 2 , wedging the lower base  58  into the pocket  46  bottom forms a sealing surface  65 . Although the threads  64  are illustrated proximate the lower base  58 , they can be formed proximate the upper base  56  or between the upper and lower bases  56 ,  58 . 
         [0018]    A space  66  is shown formed between the retainer  62  inner diameter and bellows  60  outer surface. The space  66  is in pressure communication with pressure ambient to the tubing hanger  32  and external to the pocket  46 . Normally the ambient pressure is hydrostatic water pressure and dependent on the tubing hanger  32  depth. A cavity  67  is provided within the tubing hanger  32  beneath the pocket  46 . The cavity  67  is intersected by a flow line  68  shown formed within the tubing hanger  32  in a direction away from the pocket  46  and substantially parallel to the female portion  44  axis. 
         [0019]    In one example, assembling the poppet  48  and sleeve  54  involves a bisected poppet; for example, the shaft  50  may include two shaft members connected by a threaded fitting (not shown). In this example, each section of the poppet  48  is inserted through a corresponding recess, the sleeve  54  is compressed, and the two poppet portions screwed together. In this embodiment, the action of compressing the sleeve  54  preloads the sleeve  54  such that the poppet  48  is maintained in tension in the configuration shown in  FIG. 2 . Other embodiments include threaded fittings at the poppet heads  51 ,  52  or at any location along the shaft  50 . 
         [0020]    As noted above, in the configuration of  FIG. 2 , the hydraulic coupler  34  is self-sealing and prevents fluid flow in either direction across the coupler  34 . For example, if flow or pressure were provided within the flow line  68 , the sealing surface between the poppet head  52  and lower base  58  prevents flow or fluid within flow line  68  from making its way past the coupler  34 . For flow to make its way through the coupler  34 , both the sealing surface between the upper poppet head  51  and upper base  56  and the sealing surface between the lower poppet head  52  and lower base  58  must be breached. The sealing surface between the lower poppet head  52  and lower base  58  may be breached if pressure ambient to the tubing hanger  32  is substantially larger than pressure within the cavity  67  so that the bellows  60  compresses and pushes the lower poppet head  52  away from the lower base  58 . However for fluid to flow through the coupler  34 , the upper sealing surface must also be breached. 
         [0021]      FIG. 3  illustrates an example of a flowing configuration of the hydraulic coupler  34   a . In this example, the male stinger  36  is moved downward within the pocket and aligned such that the surface of the stinger  36  around the cavity  43  is in contact with the upper base  56  but not contacting the upper poppet head  51  because of cavity  43 . Applying a downward force compresses the sleeve  54  (contracts the bellows  60 ) to breach the sealing surface between the poppet head  51  and upper base  56 . Continued downward pushing engages the poppet head  51  with the base of the cavity  43 , ultimately the male stab  36  also downwardly urges the poppet  48  to breach the seal between the lower poppet head  52  and lower base  58 . The lower poppet head  52  abuts the cavity  46  base. This provides a flow path from the flow line  40  through the distribution lines  42  and the sleeve  54  into the cavity  67  and the flow line  68 . When the male stinger  36  is removed, the bellows  60  expands to engage the upper poppet head  51 . The bias force/stored energy in the contracted bellows  60  pushes the poppet head  51  upward back to the closed position of  FIG. 2 . 
         [0022]    Sea water applies hydrostatic pressure in the space  66  and to the bellows  60  outer surface. The pressure inside the bellows  60  may be less than hydrostatic. However the hydrostatic pressure alone cannot open the coupler  34  as shown in  FIG. 3 . Referring now to  FIG. 4 , a schematic example is presented for an explanation of why forming the bellows  60  diameter where it connects to the lower base  58  to be less than the upper poppet head  51  diameter self seals the coupler  34 . As is known, the force from pressurizing a surface is a function of total surface area. Thus the pressure seal between the upper poppet head  51  and upper base  56  will be maintained if the resultant force of ambient pressure applied to the base  56  and bellows  60   a  has an upwardly directed vector. Referring back to  FIGS. 2 and 3 , and assuming the bellows  60  follows a repeating path, resulting forces taken along a period (90 degrees, 180 degrees, 360 degrees, . . . ), will cancel resulting in a net zero force directed along the axis of the coupler  34 . Thus, the simplified version in  FIG. 4  depicts the portion of the bellows  60   a  with its redundant undulations removed. From this view, it can be seen that in order to compress the sleeve  54   a , thereby breaching the seal between the upper poppet head  51  and upper base  56 , the forces resulting from applied pressure on the upper base  56  must exceed the resulting forces of applied pressure, in an upward direction, applied to the bellows  60   a . From  FIG. 4 , it can be seen that the area on the upper base  56  subject to ambient pressure is found by determining the total upper surface area of the female portion  44  (shown having diameter D 2 ) and subtracting the upper poppet head  51  area (shown having diameter D 1 ). Similarly, the upward force on the bellows  60   a  from ambient pressure is found by subtracting the area where the bellows  60   a  connects with the lower base  58  (shown having diameter D 3 ) from the total upper surface area. Accordingly, as long as D 1  exceeds D 3 , the force resulting from applied pressure will have a resultant in an upward direction, thereby maintaining the pressure seal between the upper poppet  51  and upper base  56 . This remains true even if the external hydrostatic pressure compresses the bellows  60   a  so the poppet  48  lower head  52  abuts the cavity  46  base; which prevents further compression. 
         [0023]    In one example of operation, a hydraulic connection is made between two members used in subsea hydrocarbon production, such as a running tool  10  and a tubing hanger  12 . However, other members can include a remotely operated vehicle, casing hanger, wellhead housings, and the like. Making the connection, as example of which is shown in  FIG. 3 , includes pushing the male stab  36  against the outer base  56  and breaching the pressure seal between the upper poppet head  51  and contour in the bore  57 . As noted above, the cavity  43  in the male stab  36  receives the poppet head  51  so the portion of the stab  36  around the cavity  43  can apply a force against the female member  44  to compress the tubular bellows  60 . Further downward urging of the male stab  36  ultimately engages bottom of the cavity  43  with the poppet head  51  to move the poppet  48  with respect to the sleeve  54  and breach the seal between the lower poppet head  52  and lower base  58 . The lower base  58  is always wedged against the sealing surface  65  in the pocket  46  bottom, thus allowing the lower poppet head  52  to move relative to the lower base  58  and into the cavity  67 . This creates a flow path through the bore  57 , the sleeve  54 , and bore  59  that communicates fluid between the running tool  30  and tubing hanger  32 . When fluid flow between the two members is no longer required, the compressive force against the sleeve  54  is removed by retracting the male stab  36 . The resilient bellows  60  returns to its pre-loaded configuration shown in  FIG. 2  and pulls the poppet  48  upward so that its upper and lower heads  51 ,  52  sealingly reseat into the bores  57 ,  59 . The self sealing configuration of the female portion  44  ensures flow across the coupler  34  is blocked. However, the coupler  34  can be re-engaged at a later time with a stab  36 , or other device, to provide fluid flow through the coupler  34 . 
         [0024]    The present system and method described herein, therefore, is well adapted to carry out and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. For example, the male stab  36  can engage the coupler  34  without coupling the members in which the stab  36  and coupler  34  are respectively housed, for example the tubing hanger  32  and running tool  30 . Similarly, in situations where the stab  36  and coupler  34  housings are engaged, the stab  36  can be released from the coupler  34  without disengaged their respective housings (e.g. hanger  32  and running tool  30 ). These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.