Patent Publication Number: US-11035198-B2

Title: Multifunction blowout preventer

Description:
PRIORITY APPLICATIONS 
     The present application is a U.S. National Stage Filing under 35 U.S.C. 371 from International Application No. PCT/CA2018/050025, filed Jan. 12, 2018, which claims priority from U.S. Provisional Application No. 62/446,790 filed Jan. 16, 2017. Each of which are incorporated by reference herein by in their entirety. 
    
    
     FIELD 
     Embodiments herein relate generally to wellhead control for oil and/or gas production. More specifically, a low height blowout preventer capable of accommodating free flowing and artificial lift flow techniques is provided. 
     BACKGROUND 
     A variety of techniques can be used to produce oil and gas from wells. For flowing wells, the formation pressure is sufficient to produce oil and/or gas without requiring a pump, and a flow tee can be installed on the wellhead stack to direct the wellbore fluids naturally flowing out of the well. A gate valve can be installed below the flow tee to control the production of fluids. Reservoirs may initially be at pressures sufficient for oil and gas to flow to surface naturally, but can then lose pressure over time such that a well is no longer naturally flowing. In this situation, the wellhead stack must then be retrofitted to introduce artificial lift in the wellbore in order to continue or improve production. 
     Retrofitting a formerly flowing well for artificial lift production can be a labour intensive and costly process, involving the installation of pumping equipment and safety apparatuses, as well as the removal or replacement of existing equipment to accommodate the chosen artificial lift method. Should the chosen method of artificial lift change, another retrofit may be required in order to accommodate the new method. A well can undergo several changes in production methods over the course of its life. 
     Adding equipment to the wellhead stack may increase the height of the stack significantly, which negatively impacts wellhead stability. A higher wellhead stack may also necessitate elevating the service rig, or utilizing a more expensive pump jack. Installing new equipment also introduces additional connections between the various components, consequently increasing the number of potential leak points for wellbore fluids. Adding or replacing components at the wellhead will also often lead to changes in flow lines used to transport the produced wellbore fluid away from the well. Changes in the flow line could also necessitate changes in pipe supports and associated instrumentation. 
     Additionally, disassembling and re-assembling a wellhead stack can cause wear at the connection points between components. For example, components that use threadable engagements are at risk having their threads damaged during each assembly or break up of the wellhead stack. If the thread in a component is damaged, then the entire component must be discarded and replaced. The threads and sealing surfaces in such components also wear out each time the components are assembled and disassembled, allowing for about two to four assembly/break ups before the components are no longer safe to use. Using components with flanged connections reduces the risk of damaging sealing components, but such components are time-consuming to assemble and disassemble due to the numerous bolts that must be secured to strict torque specifications. 
     There is still a need for wellhead components which mitigate the need to remove, introduce, or replace components when a change in production method is desired, reduce the overall height of the wellhead stack, and lessen the risk of damaging the components during assembly and break up. 
     SUMMARY 
     According to a broad aspect of the present disclosure, there is provided a multifunction blowout preventer comprising: a housing formed as a single piece of material and having defined therein a longitudinal bore extending axially therethrough, the housing comprising: a bottom connection for connecting to a wellbore; a gate valve section having defined therein at least one cavity in communication with the bore, each of the at least one cavity for receiving a gate valve for controlling fluid flow through the bore; an integrated ram assembly/flow tee section having defined there: at least two pairs of opposing radial bores for receiving a sealing ram assembly; at least two pairs of opposing radial locking bores for receiving a rod lock ram assembly; and one or more flow bores for removing fluid from the wellbore and/or introducing fluid to the wellbore, wherein the at least two pairs of opposing radial bores, the at least two pairs of opposing radial locking bores, and the one or more flow bores extend radially outwardly from the bore and open to an exterior wall of the housing and are in communication with the bore, and the one or more flow bores are located axially in the housing between one or both of the two pairs of opposing radial bores and the two pairs of opposing radial locking bores that are closest to the bottom connection; and a top connection for connecting to upper wellhead components. 
     According to another broad aspect of the present disclosure, there is provided a multifunction blowout preventer comprising: a housing formed as a single piece of material and having defined therein a longitudinal bore extending axially therethrough, the housing comprising: a bottom connection for connecting to a wellbore; a gas lift/electrical ports section having defined therein one or both of: a gas lift bore extending between and opening to a gas lift port on an exterior wall of the housing and the face of the bottom connection; and one or more electrical ports extending between and opening to the exterior wall and the face; a gate valve section having defined therein at least one cavity in communication with the bore, each of the at least one cavity for receiving a gate valve for controlling fluid flow through the bore; an integrated ram assembly/flow tee section having defined there: at least one pair of opposing radial bores for receiving a sealing ram assembly; at least one pair of opposing radial locking bores for receiving a rod lock ram assembly; and one or more flow bores for removing fluid from the wellbore and/or introducing fluid to the wellbore, wherein the at least one pair of opposing radial bores, the at least one pair of opposing radial locking bores, and the one or more flow bores extend radially outwardly from the bore and open to the exterior wall and are in communication with the bore; and a top connection for connecting to upper wellhead components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described by way of an exemplary embodiment with reference to the accompanying simplified, diagrammatic, not-to-scale drawings. Any dimensions provided in the drawings are provided only for illustrative purposes, and do not limit the invention as defined by the claims. In the drawings: 
         FIG. 1A  is a first perspective view of a multifunction blowout preventer according to one embodiment of the present disclosure; 
         FIG. 1B  is a second perspective view of the multifunction blowout preventer; 
         FIG. 2  is a top view of the multifunction blowout preventer; 
         FIG. 3  is a cross-sectional perspective view of the multifunction blowout preventer of  FIG. 2 , along line x-x, showing a gas lift port and flow bores (and rod R is omitted); 
         FIG. 4A  is a first side view of the multifunction blowout preventer; 
         FIG. 4B  is a second side view of the multifunction blowout preventer; 
         FIG. 5A  is a cross-sectional perspective view of the multifunction blowout preventer of  FIG. 4B , along line y-y, showing the gas lift port and electrical ports (and rod R is omitted); 
         FIG. 5B  is a cross-sectional perspective view of the multifunction blowout preventer of  FIG. 4A , along line z-z, showing a gate valve (and rod R is omitted); 
         FIG. 5C  is a cross-sectional perspective view of the multifunction blowout preventer of  FIG. 4A , along line w-w, showing a rod lock ram assembly; 
         FIG. 5D  is a cross-section perspective view of the multifunction blowout preventer of  FIG. 4A , along line v-v, showing a sealing ram assembly; 
         FIGS. 6A and 6B  are a first side view and a cross-sectional view thereof, respectively, of a main housing of the multifunction blowout preventer according to one embodiment of the present disclosure; and 
         FIGS. 7A and 7B  are a second side view and a cross-sectional view thereof, respectively, of the main housing of  FIGS. 6A and 6B . 
     
    
    
     DESCRIPTION 
     When describing the present invention, all terms not defined herein have their common art-recognized meanings. To the extent that the following description is of a specific embodiment or a particular use of the invention, it is intended to be illustrative only, and not limiting of the claimed invention. The following description is intended to cover all alternatives, modifications and equivalents that are included in the spirit and scope of the invention, as defined in the appended claims. 
       FIGS. 1A, 1B, 2, 3, 4A, and 4B  show an embodiment of a multifunction blowout preventer (BOP)  8  which is a monolithic, integrated structural block of suitable material for oil and gas operation at service pressures. The BOP  8  comprises a main housing  10 , having a longitudinal bore  12  extending therethrough for receiving a pump rod, such as a polished rod R. The housing  10  is made of a single piece of material. The housing  10  has a top connection  14  and a bottom connection  15 . 
     Top connection  14  is for sealingly connecting to upper wellhead components (not shown), such as a stuffing box. The top connection  14  is shown, for example in  FIG. 3 , as a connection having a plurality of internally threaded holes opening at its face  13  for receiving a plurality of studs therein for connection to the stuffing box. However, the top connection  14  can be a flanged connection, clamp-hub connection, or rotatable flange connection as well. 
     The bottom connection  15  is for sealingly connecting to a wellbore (not shown). The bottom connection  15  is shown, for example in  FIG. 3 , as a connection having a plurality of internally threaded holes opening at its face  16  for receiving studs therein for connection to the wellbore. However, the bottom connection  15  can be a flanged connection, clamp-hub connection, or rotatable flange connection as well. As best shown in  FIG. 3 , a seal ring groove  17  is defined in the face  16  of the bottom connection  15  and the seal ring groove  17  extends around the bore  12 , so that when a seal ring (not shown) is inserted therein and the bottom connection  15  is tightened against the wellbore, a fluid tight seal is obtained. 
     Referring now to  FIGS. 3, 4B, 5A, 6A, 6B, 7A, and 7B , the BOP  8  has a gas lift/electrical ports section in the housing  10  near the bottom connection  15 . The gas lift/electrical ports section includes a gas lift bore  30  defined in housing  10 , extending between and opening to a gas lift port  32  on the exterior wall  11  of housing  10  and the face  16  of bottom connection  15 , to allow fluid communication between the annulus, defined between the central wellbore tubing and the casing, and the exterior wall  11 . The gas lift port  32  may have a gas lift tubing  33  extending outwardly therefrom. Gas lift bore  30  allows for the use of gas injection artificial lift methods, such as injecting high pressure gas into the annulus via port  32  and bore  30  to create a differential pressure in the wellbore, thereby mobilizing and urging wellbore fluids to flow up the central wellbore tubing. Gas lift bore  30  can also allow wellbore fluids to be produced therethrough, such as with jet pump methods wherein fluid is injected down the central wellbore tubing, and wellbore fluids are produced up the annulus through the gas lift bore  30  and gas lift port  32 . 
     The gas lift/electrical ports section also includes one or more electrical ports  40  defined in housing  10 . Each electrical port  40  extends between and opens to the exterior wall  11  and a location on the bottom face  16  for communication with the annulus between the central wellbore tubing and the casing. Electrical ports  40  are sized to accommodate wiring for an electrical submersible pump (ESP) from outside the BOP  8  to the annulus while maintaining a seal to contain wellbore pressure. Ports  40  are also provided for communication and control capability to monitor the ESP or other downhole equipment through fiber optic cables, pressurized capillary tubing, or other such communication systems. Sealing threads can be provided at both ends of ports  40  for forming a seal with the wiring components of the ESP. A mounting bracket  42  can also be provided on housing  10  for mounting an electrical junction box of the ESP thereon. 
     Referring to  FIGS. 4A and 5B , the BOP  8  has a gate valve section located in housing  10  adjacent the gas lift/electrical ports section. The gate valve section has at least one cavity  19  in communication with bore  12 . Each cavity  19  accommodates a gate valve  20  configured to actuate between an open position to allow fluids and other objects to flow therethrough, and a closed position to prevent fluid communication and other objects from flowing therethrough. Gate valve  20  functions as a master valve to control fluid flow through bore  12 , for isolating the components of the BOP  8  above the gate valve  20  from wellbore pressure as required. The hand wheel and bonnet assembly  21  of gate valve  20  protrude externally of housing  10 . While the gate valve section in the illustrated embodiment shown in  FIG. 4A  has two gate valves  20 , the BOP  8  may have more or fewer gate valves in other embodiments. In some embodiments, gate valve  20  is rated at about 5000 psi, but in other embodiments, gate valve  20  can be rated higher or lower than about 5000 psi depending on the wellbore environment and pressures of the specific well. 
     Above the gate valve section, as shown in  FIGS. 6A, 6B, 7A, and 7B , the BOP  8  has an integrated ram assembly/flow tee section in housing  10 . At least one pair of opposing radial bores  50 , at least one pair of opposing radial locking bores  70 , and one or more flow bores  60  are defined in the integrated ram assembly/flow tee section. Bores  50 , locking bores  70 , and flow bores  60  each extend radially outwardly from bore  12  and open to the exterior wall  11 , and are each in communication with bore  12 . In some embodiments, each pair of bores  50  and locking bores  70  intersect bore  12  at a different axial location thereof. Flow bores  60  also intersect bore  12  at a different axial location than those of bores  50  and locking bores  70 . In the illustrated embodiment, as shown in  FIGS. 6A, 6B, 7A, and 7B , the BOP  8  has two pairs of radial bores  50  and two pairs of radial locking bores  70 , and flow bores  60  intersect bore  12  at an axial location between the two pairs of bores  50  and the two pairs of locking bores  70 . While two pairs of bores  50 ,  70  are shown in the illustrated embodiment, more or fewer pairs of bores  50 ,  70  may be included other embodiments of the BOP  8 , and flow bore  60  can be located between any adjacent pairs of bores  50  and/or bores  70 . Furthermore, while the flow bores  60  are shown in the illustrated embodiment to be located above the lowermost pair of bores  50  and locking bores  70 , the flow bores  60  may be located elsewhere axially in other embodiments. 
     As best shown in  FIG. 5D , each pair of radial bores  50  is formed to receive a sealing ram assembly  52 , comprising a pair of ram blocks  54  actuable to engage the pump rod R and a pair of ram rods  56  each extending from its respective ram block  54  through a ram housing  58  to an actuator (not shown). Ram housing  58  sealably retains ram block  54  and ram rod  56  to the housing  10 , and ram rod  56  extends sealingly through its respective ram housing  58  and substantially laterally from exterior wall  11 . Each ram housing  58  may be secured to housing  10 , for example with a flanged connection. 
     The ram assembly  52  has a deactivated position, wherein ram blocks  54  are not engaged with the pump rod R, and an activated position, wherein ram blocks  54  are driven into radial sealing engagement with the pump rod R. Ram blocks  54  can be shaped and configured to create a fluid tight seal against the exterior surface of the pump rod R. For example, an inward face  55  of each ram block  54  has a semicircular channel, fit with annular, semi-circular seals, to ensure that a substantially fluid tight seal is created when the inward face  55  is urged against the exterior surface of the pump rod R. The ram blocks  54  seal against the pump rod R when the ram blocks  54  are driven inward in the activated position. 
     One or more actuators (not shown) can be used to shift the ram assemblies  52  between the deactivated position and the activated position. A variety of actuator mechanisms may be used to move the ram assemblies  52  between their activated and deactivated positions. Such mechanisms include, for example, manual, hydraulic, pneumatic, electric actuators, and any combination thereof. The ram housings  58 , ram blocks  54  and ram rods  56  can be of conventional construction known in the art. If desired, additional pairs of radial bores  50  and ram assemblies  52  can be included in the BOP  8  to provide greater safety and redundancy. 
     As best shown in  FIG. 5C , each pair of radial locking bores  70  is formed to receive a rod lock ram assembly  72 , comprising a pair of locking ram blocks  74  and a pair of locking ram rods  76 . Each locking ram rod  76  extends from its respective locking ram block  74  through a locking ram housing  78  to an actuator (not shown). Locking ram housing  78  sealably retains locking ram block  74  and locking ram rod  76  to housing  10 , and locking ram rod  76  extends sealingly through its respective locking ram housing  78  and substantially laterally from exterior wall  11 . Each locking ram housing  78  may be secured to the housing  10 , for example with a flanged connection. 
     The rod lock ram assembly  72  has a deactivated position, wherein locking ram blocks  74  are not engaged with the pump rod R, and an activated position, wherein locking ram blocks  74  are driven into radial gripping engagement with the pump rod R to clamp the pump rod R to restrict rotational and/or axial movement of same. Ram lock blocks  74  can be shaped and configured to create a surface to matingly grip the exterior surface of the pump rod R. For example, an inward face  75  of each ram lock block  74  has a semicircular channel to matingly engage the pump R when the inward face  75  is urged against the exterior surface of the pump rod R. The ram lock blocks  74  securely grips the pump rod R when the ram lock blocks  74  are driven inward in the activated position. 
     While the depicted embodiment shows the sealing ram assemblies  52  and rod lock ram assemblies  72  as separate assemblies, it is possible to combine these. A person of skill in the art would understand that both separate and combined sealing ram and rod lock ram assemblies can be used in the multifunction BOP described herein. 
     As best shown in  FIGS. 3, 6A, and 6B , the one or more flow bores  60  are for removing fluids from the wellbore and each flow bore  60  may have a flow connection  62  connected thereto at its opening on exterior wall  11 . Flow connections  62  are configured to connect to fluid lines for transporting wellbore fluids therethrough. If more than one flow bore  60  is used, the flow bores  60  can be of equal or different diameters, such that the housing  10  may engage with fluid lines of equal or different sizes. As in the depicted embodiment, more than one flow connection  62  can be provided such that one flow connection can be used for the regular removal of produced wellbore fluid and another flow connection is available for injection for well workovers, such as hot oil injection for the removal of paraffin wax. 
     In the depicted embodiment shown in the  FIGS. 6A, 6B, 7A, and 7B , the positions of the gas lift bore  30 , electrical ports  40 , cavities  19 , bores  50 , locking bores  70 , and flow bores  60  on exterior wall  11  are axially and/or radially offset or staggered about the periphery of housing  10  so that external parts of the gas lift tubing  33 , connections to ports  40 , gate valves  20 , sealing ram assemblies  52 , rod lock ram assemblies  72 , and flow connections  62  do not interfere with one another, in order to help minimize the height of the multifunction BOP. In some embodiments, the gas lift bore  30 , electrical ports  40 , cavities  19 , bores  50 , locking bores  70 , and flow bores  60  are radially offset from one another about the periphery of housing  10 . In an alternative or additional embodiment, the gas lift bore  30 , electrical ports  40 , cavities  19 , bores  50 , locking bores  70 , and flow bores  60  are axially staggered from one another along the length housing  10 . 
     In use, when the reservoir pressure of a well is sufficient to produce well hydrocarbons to surface without assistance, the multifunction BOP  8  can be configured to have the gate valves  20  in the open position and the sealing ram assemblies  52  and rod lock ram assemblies  72  in the retracted position, while gas lift port  32  and electrical ports  40  are fluidly sealed, for example by using a threaded plug. Further, the bore  12  above the flow bores  60  is fluidly sealed such that the only flow path for fluids produced from the wellbore is through flow bores  60 . 
     When the use of artificial lift methods is desired, the multifunction BOP  8  can be reconfigured without adding or replacing any wellhead stack components. When gas lift methods are to be used, gas lift port  32  can be connected to a gas injection apparatus, to allow gas to be injected through the gas lift bore  30  into the annulus between the wellbore tubing and casing to produce fluids up the wellbore tubing. Alternatively, fluid can be injected through the wellbore tubing to produce hydrocarbons up the annulus and through gas lift port  32  via gas lift bore  30 . 
     When an ESP is to be used, wiring for the ESP can be run from an electrical junction box mounted on mounting bracket  42  through electrical ports  40  and downhole to the pump. Gas lift port  32  can be opened or sealed as needed. 
     When a reciprocating or rotating pump, such as a progressive cavity pump, is to be used, a pump, rod string, and pump rod can be inserted downhole through bore  12  to pump hydrocarbons to surface. Gas lift port  32  and electrical ports  40  can be fluidly sealed such that produced hydrocarbons flow out through flow bores  60 . The sealing ram assemblies  52  function as a blowout preventer to fluidly seal the well to prevent wellbore fluids from escaping to surface, such as when downstream equipment is removed or disassembled for servicing, and to secure the rod string in the event of a pressure increase in the wellbore that could otherwise push the pump rod and the rest of the rod string out of the wellbore. Locking ram assemblies  72  function to further secure the rod string and prevent axial or rotational movement thereof in the event of a pressure increase or to support the rod string when the pump jack is disconnected. 
     The housing  10  can be manufactured by milling a single bar or by forging or casting of material, such as steel, or by other suitable manufacturing methods. Such manufacturing method further increases the structural soundness of the multifunction BOP compared to methods such as joining components with welds. 
     The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.