Patent Publication Number: US-9410391-B2

Title: Valve system

Description:
BACKGROUND 
     Hydrocarbon fluids such as oil and natural gas may be obtained from subsea wells. Subsea test trees enable well testing and well cleanup operations to be conducted on subsea wells from an offshore floating rig. In the event the well is to be shut down, the subsea test tree includes valves for shutting in the well and for preventing discharge of the landing string contents into an associated riser. The subsea test tree also comprises a latch mechanism for safely disconnecting the landing string. 
     SUMMARY 
     In general, the present disclosure provides a system and method of utilizing a valve having a configuration which may be used in a subsea test tree. The valve comprises a valve element pivotably mounted in a housing having a passageway therethrough. The valve element may be actuated between an open position and a closed position blocking the passageway. A cutter is disposed along a first surface of the valve element and a seal system is positioned for engagement with a second surface of the valve element to provide separate cutting and sealing surfaces. Actuating the valve element from the open position to the closed position enables cutting of a conveyance, that may be positioned through the passageway, while simultaneously forming a seal along a separate surface to sealingly block the passageway. 
     However, many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and: 
         FIG. 1  is a schematic illustration of a subsea well system having a subsea test tree with a valve for sealing off a flow-through passageway through the subsea test tree, according to an embodiment of the disclosure; 
         FIG. 2  is a cross-sectional view of an example of the valve illustrated in  FIG. 1 , according to an embodiment of the disclosure; 
         FIG. 3  is an orthogonal view of an example of a valve element that may be used in the valve illustrated in  FIG. 2 , according to an embodiment of the disclosure; 
         FIG. 4  is an orthogonal view of an example of a pin member used to mount a cutting insert of the valve to a supporting housing, according to an embodiment of the disclosure; 
         FIG. 5  is an orthogonal view of an example of a cutting insert against which a conveyance may be cut during closure of the valve element, according to an embodiment of the disclosure; 
         FIG. 6  is an orthogonal view of an example of an anchor block by which the pin illustrated in  FIG. 4  may be mounted to the supporting housing, according to an embodiment of the disclosure; 
         FIG. 7  is a cross-sectional view of the valve illustrated in  FIG. 2  but in a different operational configuration, according to an embodiment of the disclosure; 
         FIG. 8  is a cross-sectional view of the valve illustrated in  FIG. 2  but in a different operational configuration, according to an embodiment of the disclosure; 
         FIG. 9  is a cross-sectional view of the valve illustrated in  FIG. 2  but in a different operational configuration, according to an embodiment of the disclosure; 
         FIG. 10  is a cross-sectional view of another example of the valve, according to an embodiment of the disclosure; 
         FIG. 11  is a cross-sectional view of the valve illustrated in  FIG. 10  but in a different operational configuration, according to an embodiment of the disclosure; 
         FIG. 12  is a cross-sectional view of the valve illustrated in  FIG. 10  but in a different operational configuration, according to an embodiment of the disclosure; 
         FIG. 13  is a cross-sectional view of another example of the valve, according to an embodiment of the disclosure; 
         FIG. 14  is a cross-sectional view of the valve illustrated in  FIG. 13  but in a different operational configuration, according to an embodiment of the disclosure; and 
         FIG. 15  is a cross-sectional view of the valve illustrated in  FIG. 13  but in a different operational configuration, according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. 
     The present disclosure generally involves a system and methodology in which a valve is used to perform both a cutting and sealing function upon closure. Such a valve may be used as a safety valve or other type of valve in a variety of subsea well applications and other well related applications. The technique utilizes a valve having a valve element pivotably mounted in a housing with a passageway therethrough. By way of example, the passageway may be designed to accommodate passage of a conveyance, e.g. coil tubing, wireline, or slickline, and/or to accommodate fluid flow. 
     The valve element may be actuated between an open position and a closed position blocking the passageway. A cutter is disposed along a first surface of the valve element and a seal system is positioned for engagement with a second surface of the valve element to provide cutting and sealing functions which are separated from each other. Actuating the valve element from the open position to the closed position enables cutting of a conveyance (that may be positioned through the passageway) while simultaneously forming a seal along a separate surface to sealingly block the passageway. 
     In certain applications, the valve may be designed as a shear/seal rotary curved gate valve which may be used to reliably and repeatedly cut a conveyance and to provide a gas tight seal after cutting of the conveyance. The cutting and sealing functions may be performed along separated surfaces to separate the functionality and to preserve the sealing surface even if the cutter/cutting surface is marred by the cutting operation. When employed in subsea test trees, the valve may be used to provide a fast acting and reliable mechanism for shutting in the well while preventing discharge of landing string contents into the riser and for disconnecting the landing string from the test ring. In some applications, the valve is designed to provide compact radial packaging while utilizing separate cutting and sealing surfaces. 
     Referring generally to  FIG. 1 , an embodiment of a system, e.g. a subsea well system, is illustrated as comprising a valve designed to shear a conveyance and to seal off a passageway. By way of example, the valve may be employed in subsea test trees and in other subsea or surface well equipment. The valve is useful in many types of operations, including service operations and production operations. Additionally, the valve may be designed to accommodate passage of many types of conveyances, including coil tubing conveyances, wireline conveyances, slickline conveyances, and other suitable conveyances. It should further be noted the valve may be used in combination with other types of equipment in both well and non-well related applications. 
     In the example of  FIG. 1 , a subsea well system  20  is illustrated as comprising a surface structure  22 , e.g. a floating rig, positioned at the sea surface  24 . The surface structure  22  may be coupled with a subsea test tree  26 , located at a seafloor  28 , by a riser  30 . The subsea test tree  26  is disposed above a well  32  which may comprise at least one wellbore  34 . In the example illustrated, a valve  36  is mounted in the subsea test tree  26  and comprises a pivotable valve element  38  which may be actuated to an open position allowing access through a subsea test tree passageway  40  or to a closed position blocking access through passageway  40 . The valve element  38  may be pivotably mounted to a supporting housing  42  which surrounds the valve element  38  and may be part of the subsea test tree  26 . In some applications, the valve  36  is a modular valve and housing  42 , as part of that modular valve  36 , is designed for connection into the subsea test tree  26  or into other suitable equipment. 
     Depending on the subsea application, a conveyance  44  may be used to convey tools and/or other equipment down through riser  30  and subsea test tree  26 . The passageway  40  is sized to accommodate passage of the tools, equipment and conveyance  44  down into wellbore  34 . Upon the occurrence of certain events, the passageway  40  may be rapidly closed to shut in the well  32  by actuating valve  36  and shifting the valve element  38  to a closed, sealed position. The valve element  38  is designed to cut through the conveyance  44  to enable the rapid closure and a sealing off of passageway  40 . Depending on the design of valve  36  and on the environment in which it is employed, a variety of actuators  46  may be used to actuate valve element  30  between open and closed positions. By way of example, actuators  46  may comprise hydraulic actuators, e.g. hydraulic pistons, electrical actuators, e.g. solenoids, electromechanical actuators, or other suitable actuators designed to rotate the valve element  38  between open and closed positions. 
     Referring generally to  FIG. 2 , an embodiment of valve  36  is illustrated. In this embodiment, valve element  38  is arcuate in shape and has a first surface, e.g. a first arcuate surface, separated from a second surface, e.g. a second arcuate surface, in a manner that separates cutting and sealing functions. By way of example, the first surface may comprise an interior surface  48  to which a cutter  50  is mounted. Cutter  50  may be formed with a cutting edge  52  attached to or integrally formed from the material used to construct valve element  38 . In this example, the second surface comprises an exterior surface  54  which forms a sealing surface. The interior surface  48  and the exterior surface  54  are separated from each other by a material thickness  56  to separate the cutting and sealing functions. It should be noted, the first and second surfaces may be reversed in some embodiments so that cutter  50  is positioned along the exterior surface. 
     With additional reference to  FIGS. 3-6 , examples of components that may be used to construct valve  36  are illustrated individually to facilitate explanation. For example, valve element  38  may be in the form of a curved gate valve having a full or partial ball valve element with a hollow interior  58  and openings  60 . Opening  60  are aligned with and form part of passageway  40  when valve  36  is in the open position illustrated in  FIG. 2 . The cutter  50  may be positioned adjacent one of the openings  60  and a relief  62  may extend from the other of the openings  60  to accommodate and receive the conveyance  44  when the valve  36  is transitioned to a closed position. In this embodiment, the ball style valve element  38  further comprises pivot openings  64  which allow the valve element  38  to rotate/pivot about pivot pins  66 . 
     Each pivot pin  66  may be designed with a generally cylindrical center region  68  sized for receipt in a corresponding pivot opening  64 . As best illustrated in  FIG. 4 , the pivot pin  66  also may comprise profiled regions  70  located at opposing longitudinal ends of the cylindrical center region  68 . The profiled regions  70  are designed to engage a corresponding opening  72  formed in a cutting insert  74  (see  FIG. 5 ) and a corresponding opening  76  formed in housing  42 . By way of example, the corresponding opening  76  may be formed in an anchor block  78  (see  FIG. 6 ) forming part of housing  42 , e.g anchor block  78  may be held in a corresponding slot of housing  42 . By way of example, profiled regions  70  and corresponding openings  72 ,  76  may be rectangular in shape (or of another suitable shape) to prevent relative rotation between the cutting insert  74  and the housing  42 /anchor block  78  when the valve  36  is assembled as illustrated in  FIG. 2 . 
     When valve  36  is assembled as illustrated in  FIG. 2 , the cutting insert  74  is located in the hollow interior  58  of valve element  38 . The cutting insert  74  comprises a hollow interior  80  which aligns with openings  60  when valve  36  is in the illustrated open position. This allows movement of conveyance  44  and/or fluids through valve  36  and along the passageway  40  extending through valve  36 . The cutting insert  74  is prevented from rotating with respect to housing  42 /anchor block  78  via engagement of profiled regions  70  with the corresponding openings  72 ,  76 . However, valve element  38  may be freely rotated/pivoted via actuator  46  about the cylindrical center regions  68  of pivot pins  66 . The cutting insert  74  supports the conveyance  44  during cutting and provides an edge for cutter  50  to act against when severing conveyance  44  during a valve closure. 
     As further illustrated in  FIG. 2 , the valve  36  comprises a seal system  82  which may comprise a seal retainer  84  for carrying a seal or seals  86 . The seal retainer  84  is designed to position seal  86  against the exterior seal surface  54  when valve  36  is transitioned to a closed position. Thus, the cutting function is performed along the interior surface  48  and the sealing function is performed along the exterior surface  54  separated from interior surface  48  by thickness  56 . In subsea well applications, the seal retainer  84  and seal  86  may be used to ensure a gas tight barrier/seal in the wellbore before disconnecting the landing string from the test string. 
     Referring generally to  FIGS. 7-9 , a cutting operation is illustrated in which the valve  36  is transitioned from an open position (see  FIG. 2 ) to a closed position (see  FIG. 9 ). When an event occurs which makes it desirable to transition valve  36  to a closed position, an appropriate signal is provided to actuator  46  which may comprise a translatable piston or other actuating device pivotably coupled to valve element  38 . The actuator  46  causes valve element  38  to pivot/rotate about pins  66  such that cutting edge  52  transitions across passageway  40 , as illustrated in  FIG. 7 . If a conveyance  44 , e.g. coil tubing, is positioned through valve  36  along passageway  40 , the pivoting movement of valve member  38  causes cutting edge  52  to cut/shear the conveyance against the corresponding edge of cutting insert  74 , as best illustrated in  FIG. 8 . However, the relief  62  located on the opposite side of valve element  38  from cutter  50  reduces the potential for double cutting the conveyance. 
     Continued transition of valve element  38  to the closed position illustrated in  FIG. 9  causes seal  86  to fully engage exterior sealing surface  54 . Because the cutting is performed at the separated, interior surface  48 , the exterior sealing surface  54  is not marred or abraded during the cutting process so as to provide a secure, repeatable, gas tight seal. After cutting the conveyance  44 , the severed portions of the conveyance  44  may be dropped or removed from the subsea test tree  26  or other equipment containing valve  36 . 
     Referring generally to  FIGS. 10-12 , another embodiment of valve  36  is illustrated. In this embodiment, valve element  38  again has arcuate inner and outer surfaces  48 ,  54 , however the cutter  50  and cutting edge  52  have been located along the exterior surface  54 . Additionally, the inner surface  48  serves as an arcuate sealing surface to provide the gas tight seal upon closure of valve  36 . Thus, the cutting function and the sealing function are again separated and occur on opposed surfaces separated by material thickness  56 . 
     Consequently, the cutting insert  74  is located outside of valve element  38  for cooperation with the external cutting edge  52  of cutter  50 . In this example, the seal system  82  is located in hollow interior  58  of valve element  38 . The seal system  82  is designed so that seal retainer  84  positions the seal or seals  86  against interior surface  48  when valve  36  is transitioned to a closed position. 
     Similar to the embodiment illustrated in  FIG. 2 , when an event occurs which makes it desirable to transition valve  36  to a closed position, an appropriate signal is provided to actuator  46  which causes valve element  38  to pivot/rotate about pins  66  such that cutting edge  52  (the external edge in this embodiment) transitions across passageway  40 , as illustrated in  FIG. 11 . If a conveyance  44 , e.g. coil tubing, is positioned through valve  36  along passageway  40 , the pivoting movement of valve member  38  causes the outer cutting edge  52  to cut/shear the conveyance  44  against the corresponding edge of external cutting insert  74 . Relief  62  reduces the potential for double cutting the conveyance. 
     Continued transition of valve element  38  to the closed position illustrated in  FIG. 12  causes seal  86  to fully engage the interior sealing surface  48 . Because the cutting is performed at the separated, exterior surface  54 , the interior sealing surface  48  is not marred or abraded during the cutting process so as to provide a secure, repeatable, gas tight seal. As with the previously described embodiment, the valve element  38  may be in the form of a full or partial ball element pivotably mounted on pivot pins  66 . In this embodiment, the pivot pins  66  may be positioned to extend between seal system  82  and housing  42 , e.g. anchor block  78 . 
     Referring generally to  FIGS. 13-15 , another embodiment of valve  36  is illustrated. In this embodiment, valve element  38  again has arcuate inner and outer surfaces  48 ,  54 , however the valve element  38  is formed as a partial ball, e.g. a half ball, which cuts along the interior surface  48  and seals along the exterior surface  54 . Again, because the cutting surfaces can become scarred due to cutting, the separation of the seal surface, e.g. arcuate surface  54 , from the cutting surface enables secure, gas tight seals even if the valve  36  undergoes repeated actuations. 
     In this embodiment, the space normally occupied by the omitted part of the ball  38  can be used to create a rigid cutting support  88  which, in combination with the cutting edge  52  located on the inside diameter of valve element  38  provides a mechanically efficient mechanism for cutting. In this example, the valve element  38  is actuated, e.g. pivoted, by an articulating actuator arm  90  which is positioned to apply force more in the direction of cutting. This directionally controlled force also creates greater efficiency with respect to cutting and enables use of a lower powered actuator  46 . By way of example, actuator  46  may comprise a hydraulic controller  92  connected to a piston member  94 . The piston member  94  is slidably mounted in housing  42  and coupled to articulating actuator arm  90  to move the actuator arm  90 , and thus the valve element  38 , upon hydraulic input from hydraulic controller  92 . In some applications, a spring member  96  may be used in cooperation with piston member  94  to bias valve member  38  toward a desired position, such as the open position illustrated in  FIG. 13 . It should be noted, however, that other types of actuators  46  may be employed as discussed above. 
     If valve  36  is to be transitioned to a closed position, an appropriate signal is provided to actuator  46 , e.g. to hydraulic controller  92 , to shift piston member  94  and to thus actuate articulated actuating arm  90 . As illustrated in  FIG. 14 , articulated actuating arm  90  pivots valve element  38  about pivot pin  66  and drives cutting edge  52  into conveyance  44 . Continued rotation of valve member  38  severs the conveyance  44  and places the external, sealing surface  54  into sealing engagement with seal  86  of seal system  82 . The separation of cutting and sealing functions combined with the efficiency of the cutting action enable rapid shut-in and disconnect operations which can be repeated. 
     The valve  36  may have a variety of configurations for use in subsea applications and other applications. Additionally, the components and materials used in constructing the valve may vary from one application to another depending on operational and environmental parameters. The cutting and sealing functions may be on opposed inner or outer surfaces or on other separated surfaces depending on the design and arrangement of valve components. Similarly, the valve actuation mechanisms may rely on hydraulic systems powered via control lines, wellbore pressures, pressure storage devices, or other suitable pressure sources. The valve actuation mechanisms also may utilize electrical actuators, electromechanical actuators, combinations of actuators, and other suitable mechanisms for achieving the desired valve actuation. Cutters and cutting edges also may be designed from a variety of components and/or materials which may be selected based on the environment and/or materials to be cut. 
     Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.