Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The embodiments of the present invention relate generally to methods and apparatus for hydraulically coupling two components. More particularly, the embodiments provide a hydraulic coupler that shifts the supply of hydraulic fluid from a first source to a second source and prevents external fluid pressure from entering the hydraulic fluid paths. Still more particularly, the embodiments of the present invention relate to hydraulic couplers for subsea equipment, such as hydraulic couplers integrated into a tubing hanger that allow selection between hydraulic control from a running tool and hydraulic control from a subsea christmas tree. 
     In performing a well completion, a tubing hanger supporting a tubing string and downhole control members is placed within a well and landed on a wellhead member, such as a subsea Christmas tree. Hydraulic control lines extend from the tubing hanger to selected downhole control members, such as a downhole safety valve or a downhole chemical injection member, for actuation and control of the downhole control members. Hydraulic control fluid passages in the wellhead member and the tubing hanger are aligned in the landed position of the tubing hanger for the supply of the hydraulic control fluid from the wellhead member through the tubing hanger to downhole control members. 
     To move the tubing hanger to the wellhead, the hanger is releasably connected to a running tool and lowered through a riser connected to the well. The running tool is disconnected from the tubing hanger after landing of the tubing hanger on the wellhead member and hydraulic connectivity has been established between the tubing hanger and the wellhead member. It is often desirable that hydraulic control fluid be supplied, or have the capability of being supplied, to certain downhole control members before the tubing hanger is landed on the wellhead member and under control of the subsea wellhead member. In order to facilitate this control, hydraulic control fluid circuitry extends through a running tool for the supply of hydraulic control fluid to the tubing hanger and the downhole control members and the tubing hanger is constructed so as to receive hydraulic signals from the running tool. 
     Thus, because it is desirable to have the downhole control members under positive hydraulic control at all times, at least two alternate hydraulic fluid paths are required for each control line, a first path from the running tool and a second path for connection to the wellhead member. During the installation of the tubing hanger, the first hydraulic fluid path from the running tool is engaged and in use but the second hydraulic fluid path is left accessible so as to facilitate subsea connection to the wellhead member. Although the second hydraulic fluid path must be able to be connected to the wellhead member, it should also be protected from the ingress of external fluids, such as fluids in the riser, that may tend to contaminate the hydraulic system or interfere with proper operation of the downhole control members. The ingress of drilling fluids from the riser is of particular concern when the drilling fluid has a much higher density or is at a higher pressure than the hydraulic fluid in the tubing hanger and running tool. 
     Therefore, it is desirable to have a system that shifts the supply of hydraulic fluid to the tubing hanger from the running tool to the wellhead member and isolates the non-active hydraulic fluid path in order to prevent contamination or interference with the desired hydraulic communication. Therefore, the embodiments of the present invention are directed to methods and apparatus for providing for the selection between two hydraulic fluid supplies while protecting the hydraulic system from contamination that seek to overcome the limitations of the prior art. 
     SUMMARY OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments provide a hydraulic coupler adapted to select the supply of fluid from a first source or a second source. The fluid selection is achieved by mechanically shifting a fluid selector with a male stab member that also supplies the second fluid source. When shifted the fluid selector positively blocks the first fluid source and opens a hydraulic pathway for the second fluid source. When the male stab is disengaged, the fluid selector is pressure biased by internal and external pressure to a position allowing fluid flow from the first fluid source and preventing external fluids from entering the hydraulic system. In certain embodiments the hydraulic coupler is horizontally installed in a tubing hanger providing horizontal porting for connection with a subsea Christmas tree and vertical porting for connection to a running tool, while preventing riser fluid contamination of the hydraulic system regardless of the differential pressure between the riser fluid and the hydraulic system. 
     In certain embodiments, the hydraulic coupler includes a body having a first fluid supply port and a fluid return port. The body, which may be attached to or integral with another component, such as a tubing hanger, includes a cavity intersecting both the first fluid supply port and the fluid return port. A selector is disposed within and sealingly engages the body cavity and has a first position that allows fluid communication between the first fluid supply port and the fluid return port. The body also includes a receptacle sealingly engaging the selector and including a fluid port that, with the selector in the first position, allows hydraulic pressure external to the coupler to bias the selector into the first position. A male stab, which includes a second fluid supply port, engages the receptacle and moves the selector from the first position to a second position. In the second position fluid communication between the first fluid supply port and the fluid return port is prevented while fluid communication is allowed between the second fluid supply port and the fluid return port. 
     In another preferred embodiment, a hydraulic coupler comprises a body having a first fluid supply port and a fluid return port in hydraulic communication. A selector is disposed within the body and has a first position that allows hydraulic communication between the first fluid supply port and the fluid return port. A receptacle is connected to the body and provides one or more fluid conduits that allow fluid pressure to bias the selector into the first position. The coupler also includes a stab having a second fluid supply port and adapted to mechanically shift the selector to a second position providing hydraulic communication between the second fluid supply port and the fluid return port and preventing hydraulic communication between the first fluid supply port and the fluid return port. 
     An alternate preferred embodiment includes a method of shifting fluid communication to a return port from a first supply port to a second supply port by providing a selector that has a first position that allows fluid communication between the first supply port and the return port. The selector is biased to the first position by external fluid pressure. Fluid supply is shifted by engaging a male stab that shifts the selector to a second position preventing fluid communication between the first supply port and the return port and allowing fluid communication between the second supply port and the return port. 
     Thus, the present invention comprises a combination of features and advantages that enable it to provide for positive selection between two hydraulic supply sources and prevent the contamination of the hydraulic system by elevated external pressures. These and various other characteristics and advantages of the preferred embodiments will be readily apparent to those skilled in the art upon reading the following detailed description and by referring to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more detailed understanding of the preferred embodiments, reference is made to the accompanying Figures, wherein: 
         FIG. 1  is a partial sectional view of one embodiment of a hydraulic coupler in a disengaged position; 
         FIG. 2  is a partial sectional View of the coupler of  FIG. 1  shown in an engaged position; 
         FIG. 3  is a schematic sectional view of a tubing hanger attached to a running tool and being run through a riser; 
         FIG. 4  is a schematic sectional view of the tubing hanger of  FIG. 3  installed in a subsea tree; 
         FIG. 5  is a partial sectional view of a hydraulic coupler in a disengaged position; and 
         FIG. 6  is a partial section view of the hydraulic coupler of  FIG. 5  shown in an engaged position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. The present invention is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present invention with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results. 
     In particular, various embodiments of the present invention provide a number of different methods and apparatus for selecting the hydraulic supply to a fluid path and protecting the fluid path from external pressure. The concepts of the invention are discussed in the context of a horizontally-oriented hydraulic coupler between a subsea tree and a tubing hanger, but the use of the concepts of the present invention is not limited to this particular application and may be applied in any hydraulic coupling application. The concepts disclosed herein may find application in other subsea oilfield components, as well as other hydraulically actuated components, both within oilfield technology and other applications to which the concepts of the current invention may be applied. 
     Referring to  FIGS. 1 and 2 , coupler  10  mounts to body  11  in threaded cavity  12  that leads into ported cavity  14  into which first fluid supply port  16  and fluid return port  18  are connected. Body  11  may be the body of a subsea component, such as a tubing hanger, or may be a separate, distinct housing constructed specifically as a coupler housing. Receptacle  20  is connected to body  11  by threads  22  and includes a stab cavity  24 , neck  26 , and hydraulic cavity  28  with shoulder  30 . Bypass port  32  provides fluid communication between stab cavity  24  and hydraulic cavity  28 . Receptacle seals  34  maintain a hydraulic seal between receptacle  20  and body  11  while stab seal  36  provides a seal between receptacle  20  and engaged stab  54 . Selector  38  includes rod  40 , flange  42  with face  44 , and selector body  46  which may accommodate spring  48 . Rod  40  seals against rod seal  50  in neck  26  while selector seal  52  seals against the wall of ported cavity  14 . Stab  54  includes a second fluid supply port  56  and a probe  58 . 
     Referring now to  FIG. 1 , hydraulic coupler  10  is shown with stab  54  in a disengaged position relative to receptacle  20 . Selector  38  is in a first position allowing fluid communication between first fluid supply port  16  and fluid return port  18 . Selector seal  52  seals against the wall of ported cavity  14  to isolate the hydraulic fluid flowing between ports  16  and  18 . The combination of fluid pressure in ported cavity  14  and force from spring  48  act to keep selector  38  in the first position with face  44  against shoulder  30 . 
     Selector  38  is also maintained in the first position by any external pressure acting on the coupler  10 . External pressure will flow through bypass port  32  filling hydraulic cavity  28 . Because a metal-to-metal seal will be formed between face  44  and shoulder  30 , the pressure balance across selector  38  will also serve to maintain the selector in the first position, enabling fluid communication between first supply port  16  and return port  18 . External fluid is prevented from entering the hydraulic system by seals  34  and  52 . Thus, regardless of the differential pressure between the external fluid and the hydraulic operating fluid (or the pressure in port cavity  14 ), selector  38  will remain in the first position preventing ingress of external fluid into the hydraulic system. 
     Referring now to  FIG. 2 , coupler  10  is shown with stab  54  fully engaged. Selector  38  is pushed into a second position by probe  58  extending from stab  54 . Once stab  54  is fully engaged, selector  38  is in the second position where seal  52  prevents hydraulic communication between first fluid supply port  16  and fluid return port  18 . Second fluid supply port  56 , which may be within stab  54 , is now in fluid communication with return port  18  via bypass port  32 , hydraulic cavity  28 , and a portion of ported cavity  14 . With selector  38  in the second position, selector seals  52  engage the wall of ported cavity  14 , sealing off first fluid supply port  16  whereby all hydraulic communication to fluid return port  18  is from the second fluid supply port  56  and communication from the first fluid supply port  16  is prevented. 
     The design and selection of seals  34 ,  36 ,  50 , and  52  are critical to the performance of coupler  10  and depend on the particular location of the seal and the pressure requirements of the system. The preferred seals are resilient thermoplastic or elastomeric seals suitable for use in hydraulic systems in subsea environments. These seals may be an o-ring, or reinforced o-ring type seals for basic, low wear applications, and may be elastomeric seals reinforced with a stiff support, such as metal or composite. For example, seal  34  is a stationary seal that is pressure balanced when the coupler  10  is disengaged (exposed to external hydraulic pressure on both sides) and is exposed to external pressure on one side and hydraulic pressure on the opposite side when the coupler is engaged. Thus, seal  34  may appropriately be a thermoplastic, metallic, or reinforced elastomeric seal. 
     In considering seals that are potentially environmental barriers and/or highly cycled, such as seals  36  and  52 , a heavier duty, more robust seal design may be appropriate. Because these seals may repeatedly be subjected to energization and pressurization, a molded, metal reinforced elastomeric seal may be appropriate. It may also be preferred that this seal have a rounded or curved shape to reduce damage to the seal during repeated cycling. Those having skill in the arts of sealing hydraulic and subsea systems would realize any number of possible seal arrangements that may appropriate in this application and any combination or selection of seals may be possible. Additionally, the force generated by the make up of threads  22  on the interface  35  between body  11  and receptacle  20  may create a metal-to-metal seal barrier between neck  26  and body  11 . 
     Referring now to  FIG. 3 , a tubing hanger  60  is shown attached to running tool  62  and being run through riser  64 , which contains riser fluid  66 . Tubing hanger  60  includes hydraulic coupler  10  as shown in  FIGS. 1 and 2 . Running tool  62  provides hydraulic fluid, via running tool stab  68 , to first fluid supply port  16 , through fluid return port  18  to conduit  70  in communication with a downhole hydraulic component (not shown), such as a downhole safety valve. In this manner, control of the downhole component can be effectuated during the running of tubing hanger  60  and the attached tubing string. 
     While being run through riser  64 , tubing hanger  60  is subjected to external pressure from the riser fluid  66 , which may have a density significantly higher than the surrounding seawater or the hydraulic fluid in the hanger. Therefore, the external pressure acting on the tubing hanger  60  is potentially much greater than the internal hydraulic pressure of the tubing system. Coupler  10  prevents the riser fluid from entering into the hydraulic system regardless of the differential pressure between the riser fluid and the hydraulic fluid. 
     Referring now to  FIG. 4 , tubing hanger  60  is shown installed into subsea tree  68 . Stab  54  has been extended by actuator  71  and is fully engaged with coupler  10 . Hydraulic fluid can now be supplied from tree  68  through second fluid supply port  56 , through fluid return port  18  to control a downhole hydraulic component. Running tool  62  is detached from tubing hanger  60  and the engagement of stab  54  into coupler  10  isolates the first fluid supply port  16  so that control of the downhole components is shifted from the running tool to the tree  68 . First fluid supply port  16  may also be fitted with a check valve (not shown) to prevent fluid from flowing from the hydraulic system out of port  16 . 
     In  FIGS. 3 and 4 , hydraulic coupler  10  is shown as a component of a tubing hanger as an example of one particular use. It is to be understood that coupler  10 , and other embodiments, may be used in other subsea hydraulic equipment. The unique combination of the ability to select and isolate a particular hydraulic source while preventing contamination from pressurized external fluids may prove useful in other applications, such as subsea manifolds, control systems, chokes, and valves. 
     Referring now to  FIGS. 5 and 6 , an alternative preferred embodiment of a hydraulic coupler  72  is installed in body  74 , which may be the body of a subsea component, such as a tubing hanger, or may be a separate, distinct housing constructed specifically as a coupler housing. Coupler  72  mounts to body  74  in threaded cavity  76  that leads into ported cavity  78  into which first fluid supply port  80  and fluid return port  82  are connected. Receptacle  84  is inserted into cavity  76  and creates a pressure barrier at seal  86 . Receptacle  84  is held in place by retainer  88  that engages body  74  at threads  90 . Receptacle  84  includes a stab cavity  92 , neck  94 , and hydraulic cavity  96  with shoulder  98 . Bypass port  100  provides fluid communication between stab cavity  92  and hydraulic cavity  96 . Selector  102  includes rod  104 , flange  106  having face  108 , and selector body  110  which accommodates spring  112 . Selector body  110  also includes fluid port  114  as well as seals  116 ,  118 , and  120  for sealing against the wall of ported cavity  78 . Rod  104  seals against rod seal  122  in neck  94 . Stab  124  includes a second fluid supply port  126  and a probe  128 . 
     Referring now to  FIG. 5 , hydraulic coupler  72  is shown with stab  124  in a disengaged position. Selector  102  is in a first position allowing fluid communication between first fluid supply port  80  and fluid return port  82 . Seals  118  and  120  seal between selector body  110  and ported cavity  78  forcing the hydraulic fluid flowing from port  80  into cavity  78 , through counterbore  79  housing spring  112 , and through fluid port  114  to return port  82 . Seal  116  prevents the hydraulic fluid from flowing out of ported cavity  78  and prevents external fluids from entering the hydraulic system. 
     Selector  102  is maintained in the first position, as shown in  FIG. 5 , by fluid pressure in ported cavity  78 , force from spring  112  against body  74  and selector  102 , and external pressure acting on body  74  and coupler  72 . With selector  102  in the first position, face  108  bears against shoulder  98  and creates a metal-to-metal seal and rod seal  122  prevents pressure from passing between rod  104  and neck  94 . External pressure is allowed to flow through bypass port  100  filling hydraulic cavity  96  in receptacle  84 . Because of the metal-to-metal seal formed between face  108  and shoulder  98 , the pressure balance across selector  102  will force the selector  102  into the first position, enabling fluid communication between first supply port  80  and return port  82 . Thus, regardless of the differential pressure between the external fluid and the hydraulic operating fluid (or the pressure in ported cavity  78 ), selector  102  will remain in the first position preventing ingress of external fluid into the hydraulic system. 
     Referring now to  FIG. 6 , coupler  72  is shown with stab  124  fully engaged. Selector  102  is pushed into a second position by probe  128  extending from stab  124 . Once stab  124  is fully engaged and sealed against seal  93 , selector  102  is in the second position where seals  118  and  120 , on each side of first fluid supply port  80 , isolate port  80  and prevent hydraulic communication between the first fluid supply port  80  and fluid return port  82 . Seal  116  is moved to a position to allow hydraulic communication between hydraulic cavity  96  in receptacle  84 . Second fluid supply port  126 , integrated into stab  124 , is now in fluid communication with return port  82  via bypass port  100  and hydraulic cavity  96 . With selector  102  in the second position, all hydraulic communication to fluid return port  82  is from the second fluid supply port  126  and communication from the first fluid supply port  80  is prevented. 
     As with the seals of coupler  10 , the design and selection of seals  86 ,  93 ,  116 ,  118 ,  120 , and  122  are critical to the performance of coupler  72  and depend on the particular location of the seal and the pressure requirements of the system. The preferred seals are resilient thermoplastic or elastomeric seals suitable for use in hydraulic systems in subsea environments. These seals may be an o-ring, or reinforced o-ring type seals for basic, low wear applications, and may be elastomeric seals reinforce with a stiff support, such as metal or composite. For example, seal  86  is a stationary seal that is pressure balanced when the coupler  72  is disengaged (exposed to external hydraulic pressure on both sides) and is exposed to external pressure on one side and hydraulic pressure on the opposite side when the coupler is engaged. Thus, seal  86  may appropriately be a thermoplastic, metallic, or reinforced elastomeric seal. 
     In considering seals that are potentially environmental barriers and/or highly cycled, such as seals  93 ,  116 ,  118 ,  120 , and  122 , a heavier duty, more robust seal design may be appropriate. Because these seals may repeatedly be subjected to energization and pressurization, a molded, metal reinforced elastomeric seal may be appropriate. It may also be preferred that this seal have a rounded or curved shape to reduce damage to the seal during repeated cycling. Those having skill in the arts of sealing hydraulic and subsea systems would realize any number of possible seal arrangements that may appropriate in this application and any combination or selection of seals may be possible. Additionally, the force generated by the make up of threads  90  on the interface  87  between body  74  and receptacle  84  may create a metal-to-metal seal barrier at this interface. 
     The embodiments set forth herein are merely illustrative and do not limit the scope of the invention or the details therein. It will be appreciated that many other modifications and improvements to the disclosure herein may be made without departing from the scope of the invention or the inventive concepts herein disclosed. Because many varying and different embodiments may be made within the scope of the present inventive concept, including equivalent structures or materials hereafter thought of, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.

Technology Category: f