Patent Publication Number: US-11391106-B2

Title: Nightcap assembly for closing a wellhead and method of using same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Patent Application No. 62/638,801 filed on Mar. 5, 2018, the entire contents of which is hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     The present disclosure relates generally to oilfield technology. More specifically, the present disclosure relates to devices for closing (e.g., securing, capping, and/or sealing) wellheads and/or wellbores at a wellsite. 
     Wells are drilled into subsurface formations to reach subsurface targets, such as valuable hydrocarbons. Drilling equipment is positioned at the surface and drilling tools are advanced into the subsurface formation to form wellbores. Once drilled, casing is inserted into the wellbore and cemented into place. 
     Wellheads are positioned at the opening of the wellbore and secured to the casing. The wellhead supports various surface equipment for performing wellsite operations. See, e.g., Patent/Application Nos. US2016/0273295, U.S. Pat. Nos. 4,442,892, 7,341,109, 5,107,931, 7,051,804, US20080210435 and U.S. Pat. No. 5,005,650, the entire contents of which are hereby incorporated by reference herein. In some cases, pressure control equipment, such as blowout preventers, are connected to the wellhead and activated at increased pressures to prevent blowouts. 
     Downhole equipment is deployed through the wellhead and into the wellbore for performing downhole operations. See, e.g., Patent/Application Nos. U.S. Pat. Nos. 6,085,837, 9,683,425, and US20150226048, the entire contents of which are hereby incorporated by reference herein. In some cases, downhole equipment is deployed through the surface equipment and the wellhead. For example, downhole injection tools can be lowered through the pressure control equipment, the wellhead, and into the wellbore. 
     Despite the advancements in oilfield and/or wellhead technology, there remains a need to quickly and safely close the wellbores. The present disclosure is directed at providing such needs. 
     SUMMARY 
     In at least one aspect, the present disclosure relates to a nightcap assembly for closing a wellhead assembly positioned about a wellbore. The nightcap assembly comprises a boom and a hoist. The boom comprises a boom cylinder connectable to the wellhead assembly and a boom piston extendable from the cylinder. The hoist comprises a hoist cylinder connectable to the wellhead assembly and a hoist piston extendable therefrom. The hoist piston comprises a support member to carry a nightcap. The hoist is connectable to the boom piston and movable therewith whereby the nightcap may be inserted into an opening of the wellhead assembly. 
     The nightcap assembly further comprises a nightcap support. The hoist and the boom are connectable to the wellhead assembly by the nightcap support. The nightcap support comprises a ring with wings. The boom piston is slidably connected to the hoist by a slider. 
     The nightcap assembly further comprises eyebolts connecting the boom piston to the slider, and/or eyebolts connecting each of the hoist pistons to the support member. The wellhead assembly comprises a wellhead, and/or further comprises a hydraulic disconnect. 
     The nightcap assembly further comprises a remote actuator to selectively extend and retract the boom piston and the hoist piston. The remote actuator comprises a hydraulic pump. 
     In another aspect, the disclosure relates to a nightcap system for closing a wellhead assembly positioned about a wellbore. The nightcap assembly comprises a nightcap, a boom and a piston. The boom comprises a boom cylinder connectable to the wellhead assembly and a boom piston extendable from the cylinder. The hoist comprises a hoist cylinder connectable to the wellhead assembly and a hoist piston extendable therefrom. The hoist piston comprises a support member to carry a nightcap. The hoist is connectable to the boom piston and movable therewith whereby the nightcap may be inserted into an opening of the wellhead assembly. 
     The nightcap system further comprises a hydraulic disconnect. The hydraulic disconnect comprises a sealer to sealingly engage with the nightcap. The sealer comprises a clamp comprising dogs rotatable into sealing engagement with the nightcap. 
     Finally, in another aspect, the disclosure relates to a method of closing a wellhead assembly positioned about a wellbore. The method comprises connecting a boom and a hoist to the wellhead assembly, connecting the hoist to the boom, supporting a nightcap on the hoist, and inserting the nightcap into the opening of the wellhead assembly by selectively extending the boom and the hoist. 
     The inserting comprises remotely activating the boom and the hoist. The connecting the hoist to the boom comprises slidably connecting the hoist to the boom, and/or slidably connecting the boom to the hoist. The inserting comprises: extending the hoist; extending the boom; retracting the hoist; and retracting the boom. The inserting further comprises rotating the hoist and the boom. 
     The disclosure also relates to an apparatus for closing a wellhead, comprising: a nightcap; and a nightcap assembly. 
     This Summary is not intended to be limiting and should be read in light of the entire disclosure including text, claims and figures herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the above recited features and advantages of the present disclosure can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof that are illustrated in the appended drawings. The appended drawings illustrate example embodiments and are, therefore, not to be considered limiting of its scope. The figures are not necessarily to scale and certain features, and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness. 
         FIG. 1  is a schematic diagram depicting a pad with multiple wellsites, the wellsites having a wellhead assembly, a wellhead assembly with a nightcap assembly and a hydraulic disconnect, and a wellhead assembly with a hydraulic disconnect, respectively. 
         FIG. 2  is a schematic diagram depicting the wellhead assembly with the nightcap assembly. 
         FIGS. 3A-3B  are front view and side view, respectively, of the wellhead assembly with a ring nightcap assembly. 
         FIG. 4  is an exploded view of the wellhead assembly with the ring nightcap assembly. 
         FIGS. 5A-5B  are longitudinal cross-sectional views of the wellhead assembly depicting the ring nightcap assembly in an open and a closed position, respectively. 
         FIGS. 6A-6D  are schematic views of the wellhead assembly depicting a sequence of operation of the ring nightcap assembly. 
         FIGS. 7A-7E  are schematic views of another wellhead assembly depicting a sequence of operation of a sleeve nightcap assembly. 
         FIGS. 8A-8B  are front view and side view, respectively, of the wellhead assembly with a hinged nightcap assembly. 
         FIG. 9  is an exploded view of the wellhead assembly with the hinged nightcap assembly. 
         FIGS. 10A-10B  are longitudinal cross-sectional views of the wellhead assembly depicting the hinged nightcap assembly in an open and a closed position, respectively. 
         FIGS. 11A-11D  are schematic views of the wellhead assembly depicting a sequence of operation of the hinged nightcap assembly. 
         FIGS. 12A-12B  are schematic views of portions of nightcap assemblies having booms with lift brackets. 
         FIG. 13  is a flow chart depicting a method of closing a wellhead assembly. 
     
    
    
     DETAILED DESCRIPTION 
     The description that follows includes exemplary apparatus, methods, techniques, and/or instruction sequences that embody techniques of the present subject matter. However, it is understood that the described embodiments may be practiced without these specific details. 
     This disclosure relates to wellhead assemblies positioned at an opening of a wellbore of a wellsite. The wellhead assemblies are provided with nightcap assemblies positioned about the wellhead for closing (e.g., securing, capping, and/or sealing) the wellbore. The nightcap assemblies may be retractable to allow access through the wellhead, and activatable to secure the wellbore in a closed position. The nightcap assembly may be attached to the wellhead and moved between an open and the closed position by remote actuation. 
     The nightcap assembly may be removably connected to the wellhead and/or other portion of the wellhead assembly. The nightcap assembly may be automatically and/or manually, remotely and/or locally activated to selectively open and close the wellhead assembly. The nightcap assembly may be configured for use with a variety of surface, downhole, wellhead, and/or associated equipment. 
     The nightcap assembly may be provided with features, such as single piston, dual piston, hinged configurations, and various boom configurations to facilitate lifting, placing, and supporting the nightcap. The nightcap assembly may also be provided with one or more of the following among other features: efficient installation and/or operation, hands free operation, increased safety, flexible operation, adaptability to various wellsites, remote actuation, balanced forces, ease of installation, ease of transfer between wellheads, ease of actuation, ease of insertion and/or removal, usable with wellheads having one or more wellhead valves, capable of sealing with the wellhead equipment, etc. 
       FIG. 1  is a schematic diagram depicting a wellsite  100  having a pad  101  with multiple wells  102   a - c . The wells  102   a - c  have wellbores  106   a - c , the wellbores  106   a - c  having various shapes and sizes that extend into the subterranean formation as indicated by the dashed lines. The wellsite  100  may include surface equipment  104  positioned about the pad  101 . While a pad  101  with three production wells  102   a - c  are depicted, any number of wells may be positioned about one or more pads of one or more wellsites. The example shown is not intended to be limited to a specific application or configuration. 
     The surface equipment  104  may include a crane  108 , pressure control equipment  110 , downhole equipment  112 , and wellhead assemblies  114   a - c . The crane  108  (or other lifting and/or transport equipment) may be positioned at the wellsite  100  for deploying the pressure control equipment  110  (and/or other equipment) about the wellsite  100 . The crane  108  may be used to selectively carry the pressure control equipment  110  to and/or from one or more of the wells  102   a - c  for connection to the wellhead assemblies  114   a - c.    
     The pressure control equipment  110  may be, for example, a blowout preventer, wireline lubricator, and/or other surface equipment positionable about the wellsite  100 . The pressure control equipment  110  may have the downhole equipment  112  positioned therein. The downhole equipment  112  may be, for example, a downhole tool (e.g., injection tool) to be deployed through the pressure control equipment  110  and into the wellbores  106   a - c  for performing downhole operations. 
     The wellhead assemblies  114   a - c  are positioned about each of the wellbores  106   a - c , respectively, after the wellbores  106   a - c  are drilled and completed. The wellhead assemblies  114   a - c  each include a wellhead  116  made of metal tubing positioned about an opening of the wellbores  106   a - c  to secure equipment, such as a Christmas tree, at an uphole end thereof. A downhole end of the wellhead  116  may be secured to casing  119  lining the wellbores  106   a - c.    
     Each wellhead assembly  114   a - c  has a passage  117  in fluid communication with the wellbore, and valve(s)  118  positioned about the passage  117  to restrict fluid flow therethrough. Each of these wellhead assemblies  114   a - c  may selectively permit the downhole equipment  112  to pass through the passage  117  and into the wellbores  106   a - c . Each of the valves  118  may selectively open and close to selectively isolate fluid flow through the passage  117 . 
     The wells  102   a - c  show various devices that may be used for assuring that the wellhead assembly  114   a - c  is closed. These devices may be means for closing (or capping) the well  102   a - c  to assure that no material enters or exits the wellbores  106   a - c . The wellhead assemblies  114   a - c  are depicted as having one or more individual valves  118  along the passage  117 . For descriptive purposes, these valves  118  are schematically depicted as discrete valves positioned along certain parts of the passage  117 , but each valve may be a more complex hydraulic assembly capable of closing a portion of the passage  117 . 
     The wellhead assembly  114   a  includes two valves  118  for closing well  102   a . In this configuration, when no pressure control equipment  110  is attached to the wellhead  116 , the valves  118  are both closed. Once the crane  108  places the pressure control equipment  110  on the wellhead  116  and it is secured in place (e.g., bolted onto the wellhead  116 ), both valves  118  are opened to allow the downhole equipment  112  to pass into the wellbore  106   a.    
     The wellhead assembly  114   c  is similar to the wellhead assembly  114   a  (including two valves), except that it also includes a hydraulic disconnect  120  positioned about an inlet of the wellhead assembly  114   c . The hydraulic disconnect  120  may be a device positioned about an inlet of the wellhead assembly  114   c  to receive and engage the pressure control equipment  110  at the wellhead  116 . In the example shown, the hydraulic disconnect  120  has a funnel shaped inlet or tulip  121   a  to receive the pressure control equipment  110 . The hydraulic disconnect  120  also has a clamp  121   b  to grippingly engage the pressure control equipment  110  that passes into the hydraulic disconnect  120  to form a seal therewith. 
     The wellhead assembly  114   b  of well  102   b  is similar to the wellhead assembly  114   c , except that it has only one valve  118  and also includes a nightcap assembly  124 . The ring nightcap assembly  124  is positioned about the hydraulic disconnect  120  to insert a nightcap assembly  124  into the wellhead assembly  114   b . Like the pressure control equipment  110  of well  102   c , the ring nightcap assembly  124  may be sealingly engaged by the clamp  121   b  of the hydraulic disconnect  120  to seal the passage  117  and close the wellhead assembly  114   b  and the well  102   b  as is described further herein. 
     While  FIG. 1  shows various wells  102   a - c  with various configurations to close the passage  117  and seal the wellbore  106   a - c , a variety of configurations may be provided. In these examples, when the pressure control equipment  110  is secured to the wellhead assembly  114 , the valves are open to permit passage of the downhole equipment  112  through the passage  117  and into the wellbore  106   a - c.    
       FIG. 2  is a schematic diagram depicting an example well  202  in which the ring nightcap assembly  124  may be used. The well  202  includes a wellhead assembly  214 , the pressure control equipment  110 , the hydraulic disconnect  120 , and the ring nightcap assembly  124 . In this example, the pressure control equipment  110  is connected to the hydraulic disconnect  120 . 
     The wellhead assembly  214  may include the wellhead  116  and the hydraulic equipment  226 . The hydraulic equipment  226  may be connected between the wellhead  116  and the casing in the wellbore (not shown). The hydraulic equipment  226  may include devices, such as pressure control equipment, pumping, and/or other equipment for operating the well  202 . The hydraulic disconnect  120  may be any device capable of hydraulically disconnecting the wellhead  116 , such as RIGLOCK™ commercially available from FHE™ at www.builtbyfhe.com. 
     As also shown in  FIG. 2 , the well  202  may have a surface unit  228  and a hydraulic unit  230 . The surface unit  228  may include various devices, such as a central processing unit (CPU), input/output (I/O) devices, power supplies, transceivers, wired and/or wireless connections, measuring devices (e.g., gauges, transducers, etc.), for operating the surface equipment. The hydraulic unit  230  may include hydraulic equipment  226 , such as pumps, fluid sources, etc., for providing pressurized fluid to and/or releasing pressurized fluid from the well  202 . This hydraulic unit  230  may be coupled to the hydraulic disconnect  120  and/or the ring nightcap assembly  124  for hydraulic actuation thereof as is described further herein. 
       FIGS. 3A-6D  show various views of the hydraulic disconnect  120  and the ring nightcap assembly  124  in a ring configuration.  FIGS. 3A, 3B, and 4  show front, side, and exploded views, respectively, of the hydraulic disconnect  120  and the ring nightcap assembly  124 .  FIGS. 5A and 5B  show longitudinal cross-sectional views of the ring nightcap assembly  124  in the open position and the closed position, respectively.  FIGS. 6A-6D  show an example operation using the ring nightcap assembly  124 . As shown by these figures, the ring nightcap assembly  124  carries the nightcap  332  for insertion into the passage  117  of the hydraulic disconnect  120 . The nightcap  332  is shaped for receipt into the passage  117  and for sealing engagement by the hydraulic disconnect  120 . 
     Referring first to  FIGS. 3A-5B , the hydraulic disconnect  120  includes the tulip  121   a , the clamp  121   b , and the base  334 . The tulip  121   a  is a funnel shaped member shaped to receive the pressure control equipment ( 110  of  FIG. 1 ). The tulip  121   a  is supported on the base  334 . The base  334  defines a structure for receiving and supporting the pressure control equipment  110 , and for movably supporting the ring nightcap assembly  124 . 
     The base  334  includes a tulip ring  334   a , a sleeve  334   b , a sleeve ring  334   c , a shaft  334   d , and a wellhead connector  334   e . The sleeve  334   b  and the shaft  334   d  are tubular members defining the passage  117  for receiving the downhole tool  112  ( FIG. 1 ). The sleeve  334   b  is threadedly connected to the tulip ring  334   a  at one end and the shaft  334   d  at the other end. The shaft  334   d  is connected to the wellhead  116  ( FIG. 1 ). 
     The tulip ring  334   a  is slidably positioned about a periphery of an upper end of the sleeve  334   b . The sleeve ring  334   c  is threadedly connected about the periphery of a lower end of the sleeve  334   b  and the wellhead connector  334   e  is threadedly connected about a periphery of the shaft  334   d . The wellhead connector  334   e  is positioned adjacent the sleeve ring  334   c.    
     The clamp  121   b  is movably connected to the sleeve  334   b . The clamp  121   b  includes dogs  336   a , pivots  336   b , and long bolts  336   c . The dogs  336   a  have holes  337   a , receptacles  337   b , and tips  337   c . The holes  337   a  are shaped to receive portions of the sleeve  334   b  such that the dogs  336   a  are rotatably connected about openings in the sleeve  334   b . Shoulders of the dogs  336   a  may be moved through the sleeve  334   b  to engage the nightcap  332 . The tips  337   c  engage an inner surface of the tulip ring  334   a . The long bolts  336   c  extend through the sleeve ring  334   c  and the wellhead connector  334   e . The long bolts  336   c  are slidably movable through the sleeve ring  334   c  and the wellhead connector  334   e  as the locking dogs  336   a  and the pivots  336   b  rotate as is described further herein. 
     The ring nightcap assembly  124  includes a nightcap support  338   a , boom  338   b , hoist  338   c , and the nightcap  332 . The nightcap support  338   a  includes a support ring  340   a  and support wings  340   b . The support ring  340   a  is positioned on the sleeve ring  334   c  and/or the wellhead connector  334   e . The support wings  340   b  include a pair of fixed portions that extend below the support ring  340   a  and a pair of movable portions pivotally connected to the fixed portions. 
     The boom  338   b  includes a pair of boom cylinders  342   a  pivotally connected to an end of the movable portions of the support wings  340   b . Each boom cylinder  342   a  includes a boom piston  342   b  extendable therefrom and sliders  342   c  movably positioned along the boom pistons  342   b . Each of the sliders  342   c  may be fixed to the boom  338   b , with each slider  342   c  having holes therethrough to slidingly receive the boom pistons  342   b . Boom eyebolts  342   d  are connected to an end of each piston  342   b . A support member  342   e  is connected to the boom eyebolts  342   d  and supports the nightcap  332  thereon. The support member  342   e  is shown as a bar to rotatably support the nightcap  332 . 
     The hoist  338   c  includes a pair of hoist cylinders  344   a  with hoist pistons  344   b  and hoist eyebolts  344   c . The hoist pistons  344   b  extend from the hoist cylinders  344   a  and have the hoist eyebolts  344   c  at an end thereof. Connectors  345  pivotally connect the boom cylinders  342   a  and the hoist cylinders  344   a  to the nightcap support  338   a , and the hoist eyebolts  344   c  to the sliders  342   c.    
       FIGS. 6A-6D  show a sequence of operation of the ring nightcap assembly  124 .  FIGS. 6A-6D  show the ring nightcap assembly  124  in the retracted, extended, lifted, and closed positions, respectively. In the retracted position of  FIG. 6A , the ring nightcap assembly  124  supports the nightcap  332  adjacent the hydraulic disconnect  120  for insertion into the passage  117  to close and seal the wellhead  116  ( FIG. 1 ). 
     In the retracted position of  FIG. 6A , the boom piston  342   b  of the boom  338   b  is retracted and the hoist piston  344   b  of the hoist  338   c  is extended. The boom  338   b  is rotated by extension of the hoist piston  344   b  as indicated by the curved arrow. In the extended position of  FIG. 6B , the boom piston  342   b  of the boom  338   b  extends to move the nightcap  332  outward as indicated by the arrow. 
     In the lifted position of  FIG. 6C , the piston  342   b  of the boom  338   b  remains extended as the piston  344   b  of hoist  338   c  is retracted as indicated by the straight arrow. The retraction of the piston  344   b  rotates the boom  338   b  as indicated by the curved arrow. In the closed position of  FIG. 6D , the boom piston  342   b  is retracted to pull the nightcap  332  into the tulip  121   a  as indicated by the downward arrow. In the closed position of  FIG. 6D , the clamp  121   b  ( FIG. 5B ) may be activated to seal with the nightcap  332 . The nightcap  332  may be sealed by various means, such as gaskets, sealing pistons, and/or other devices. The process may be reversed to remove the nightcap  332  from the hydraulic disconnect  120 . 
     As shown by the example of  FIGS. 5A-5B , the nightcap  332  may be sealed in the passage  117  by activating the dogs  336   a  to rotate from the open position of  FIG. 5A  to the closed position of  FIG. 5B . The long bolts extend vertically upward to rotate the pivots  336   b  which then rotate the dogs  336   a . The dogs  336   a  extend through the openings in the sleeve  334   b  and grippingly engage the nightcap  332 . The tulip ring  334   a  may be lowered over the tips  337   c  of the dogs  336   a  to secure (lock) the dogs  336   a  in the sealed position. In this closed position, a downhole end of the nightcap  332  is fittingly received into the shaft  334   d  for sealing engagement therewith thereby securing the well in the closed position. 
     The ring nightcap assembly  124  may be operated by manual and/or automatic activation. The hydraulic unit  230  may include or be coupled to valves, pistons, or other devices that may be used to move parts of the ring nightcap assembly  124  for actuation thereof. For example, the hydraulic unit  230  may be fluidly coupled to the boom and/or hoist cylinders  342   a ,  344   a  to selectively drive the boom and/or hoist pistons  342   b ,  344   b  to move the nightcap  332  into position. Similarly, the dogs  336   a  may be provided with a piston connected to the long bolts  336   c  to selectively move the long bolts  336   c  and thereby the pivots  336   b  and the dogs  336   a  to selectively seal with the nightcap  332 . 
     Devices, such as controllers (electric, hydraulic, pneumatic, etc.), sensors, communicators, remote controllers, and/or other devices (e.g., surface unit  228  of  FIG. 2 ), may be coupled to the hydraulic unit  230  and/or the ring nightcap assembly  124 , the clamp  121   b , and/or the hydraulic disconnect  120  to trigger actuation thereof (locally and/or remotely). The controllers may include and/or be coupled to the surface unit  228  ( FIG. 2 ) for monitoring and control of operation. The hydraulic unit  230  and/or the surface unit  228  may be provided with remote controllers for remote actuation. 
       FIGS. 7A-7E  show the hydraulic disconnect  120  with a sleeve piston nightcap assembly  724  in a sleeve configuration. These figures show operation of the sleeve nightcap assembly  724  as it places the nightcap  332  into the hydraulic disconnect  120 . This version is similar to the previous version, except that the sleeve nightcap assembly  724  has a different configuration.  FIGS. 7A-7E  show the sleeve nightcap assembly  724  in the retracted, extended, further extended, lifted, and closed position, respectively. 
     As shown in  FIGS. 7A-7E , the sleeve nightcap assembly  724  may include a tubular sleeve  747  positioned on an outer surface of the hydraulic disconnect  120 . The sleeve  747  may be interference fit or connected to one or more portions of the hydraulic disconnect  120 . Optionally, this sleeve  747  may be incorporated into the hydraulic disconnect  120  for use therewith. As shown, the sleeve  747  is a cylindrical member that fits about a periphery of a portion of the hydraulic disconnect  120 , but can be any shape and/or material capable of supporting the sleeve nightcap assembly  724  about the hydraulic disconnect  120 . 
     The sleeve nightcap assembly  724  includes a boom  738   b  and a hoist  738   c . In this version, the booms  738   b  and the hoists  738   c  are pivotally connected to the sleeve  747  by the connectors  345 . Optionally, the booms  738   b  and hoists  738   c  may be connected directly to the hydraulic disconnect  120 . The sleeve nightcap assembly  724  may be connected to the hydraulic unit  230  and/or the surface unit  228  for operation therewith ( FIGS. 5A-5B ). 
     In the retracted position of  FIG. 7A , the boom  738   b  and the hoist  738   c  are retracted and the nightcap  332  is at rest adjacent to the open hydraulic disconnect  120 . In  FIG. 7B , the piston  744   b  of the hoist  738   c  has extended as indicated by the horizontal arrow. In  FIG. 7C-7D , the piston  742   b  of the boom  738   b  also extends as indicated by the straight arrow. The extension of piston  742   b  causes the boom  738   b  and the hoist  738   c  to rotate as indicated by the curved arrows until the nightcap  332  is in the vertical position above the tulip  121   a . In  FIG. 7E , the nightcap  332  is lowered into the tulip  121   a  by retraction of the piston  744   b  of the hoist  738   c . The process may be reversed for removal of the nightcap  332  and/or insertion of the downhole equipment (e.g.,  112  of  FIG. 1 ). 
       FIGS. 8A-11D  show another nightcap assembly  824  in a bracket configuration.  FIGS. 8A-10B  show various views of the bracket nightcap assembly  824 .  FIGS. 8A, 8B, and 9  show front, side, and exploded views, respectively, of the hydraulic disconnect  120  and the bracket nightcap assembly  824 .  FIGS. 10A and 10B  show longitudinal cross-sectional views of the bracket nightcap assembly  824  in the open position and the closed position, respectively.  FIGS. 11A-11D  show an example operation using the bracket nightcap assembly  824 . As shown by these figures, the bracket nightcap assembly  824  carries the nightcap  332  for insertion into the passage  117  of the hydraulic disconnect  120 . The nightcap  332  is shaped for receipt into the passage  117  and for sealing engagement by the hydraulic disconnect  120 . 
     The hydraulic disconnect  120  is the same as previously described. The bracket nightcap assembly  824  is similar to the ring nightcap assembly  324  of  FIGS. 3A-6D , and is provided with similar versions of the nightcap support  338   a , the boom  338   b , the hoist  338   c , support bar  842   e , and the nightcap  332 . As shown by the version of  FIGS. 8A-10B , various connectors and supports can be provided to facilitate operation of the nightcap assembly  824 . For example, this configuration seeks to ensure proper seating of the nightcap  332  in the hydraulic disconnect  120  without causing interference with the boom  338  or the hoist  338   c  even in the fully retracted position. In another example, this configuration seeks to enable hoisting of the nightcap assembly  824  by crane (e.g.,  108  of  FIG. 1 ) without transferring loads to the nightcap assembly  824 . 
     In this version, the sliders  342   c  of  FIGS. 3A-6D  have been replaced with a lift bracket (u-bracket)  845  connected to each of the booms  338   b . The lift bracket  845  is a u-shaped member including arms  847   a  joined by a bar  847   b . Each arm  847   a  is connected to one of the booms  338   b . Each arm  847   a  is also provided with a key  849 . The keys  849  are vertical members with a receptacle  851  at one end and a linear surface engagable with the arm  847   a  to maintain the key  849  in vertical alignment with the boom  338   b . The receptacle  851  is shaped to receive the support bar  842   e . The support bar  842   e  is rotatably supported on the pistons  342   b  by eyebolts  842   d . The support bar  842   e  is provided with connectors to rotatably support the nightcap  332  thereon. 
       FIGS. 11A-11D  show a sequence of operation of the bracket nightcap assembly  824 .  FIGS. 11A-11D  show the bracket nightcap assembly  824  in the retracted, extended, lifted, and closed positions, respectively, in a similar manner as the ring nightcap assembly  324  of  FIGS. 6A-6D . In the retracted position of  FIG. 11A , the boom piston  342   b  of the boom  338   b  is retracted and the hoist piston  344   b  of the hoist  338   c  is extended. The boom  338   b  is rotated by extension of the hoist piston  344   b  as indicated by the curved arrow. In the extended position of  FIG. 6B , the boom piston  342   b  of the boom  338   b  extends to move the nightcap  332  outward as indicated by the arrow. 
     In the lifted position of  FIG. 11C , the piston  342   b  of the boom  338   b  remains extended as the piston  344   b  of hoist  338   c  is retracted as indicated by the straight arrow. The retraction of the piston  344   b  rotates the boom  338   b  as indicated by the curved arrow. In the closed position of  FIG. 11D , the boom piston  342   b  is retracted to pull the nightcap  332  into the tulip  121   a  as indicated by the downward arrow. In the closed position of  FIG. 11D , the clamp  121   b  ( FIG. 5B ) may be activated to seal with the nightcap  332  as previously described herein for  FIGS. 6A-6D . The process may be reversed to remove the nightcap  332  from the hydraulic disconnect  120 . 
     Referring to  FIGS. 9, 12A and 12B , the nightcap  332  is supported on the support bar  842   e  by a swivel  841   a  and a pin  841   b . The swivel  841   a  has a hole shaped to receive the support bar  842   e , and a keyway  849  shaped to receive an upper end of the nightcap  332 . The keyway  849  has holes to receive the pin  841   b . A locking member (e.g., locking pin)  843  may extend through the pin  841   b  to rotatably secure the pin  841   b  in place. A clasp  841   c  may also be secured to the swivel  841   a  to receive a cable or other supporting member therethrough for lifting the nightcap  332  and/or bracket nightcap assembly  824  (e.g., by crane  108 ). As shown in  FIG. 12B , a collar  848  may optionally be provided about the support bar  842   a  to secure the swivel  841   a  axially along the support bar  842   a  and between the pistons  342   b.    
       FIG. 13  is a method flow chart showing a method  1300  of closing a wellhead assembly. The method  1300  comprises:  1350 —connecting a boom and a hoist to the wellhead assembly;  1352 —connecting the hoist to the boom,  1354 —supporting a nightcap on the hoist; and  1356 —inserting the nightcap into the opening of the wellhead assembly by selectively extending the boom and the hoist. Portions of the method may be performed in any order and repeated as desired. 
     The connecting  1352  may involve slidably connecting the hoist to the boom as shown, for example, in  FIGS. 6A-6D , slidably connecting the boom to the hoist as shown, for example, in  FIGS. 7A-7E , and/or supportingly connecting the boom to the hoist as shown, for example in  FIGS. 11A-11D . 
     The inserting may involve remotely activating the boom and the hoist as shown, for example, in  FIGS. 5A-5B . The inserting may also involve extending the hoist; extending the boom; retracting the hoist; and retracting the boom as shown in the examples of  FIGS. 6A-6D and/or 7A-7E .  FIGS. 6A-7E  also show rotating the hoist and the boom during the inserting.  FIGS. 11A-11D  also show supporting the pistons during the inserting. 
     While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions and improvements are possible. For example, various combinations of one or more of the features and/or methods provided herein may be used. 
     Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter. 
     For example, while certain connectors are provided herein, it will be appreciated that various forms of connection may be provided. 
     Insofar as the description above and the accompanying drawings disclose any additional subject matter that is not within the scope of the claim(s) herein, the inventions are not dedicated to the public and the right to file one or more applications to claim such additional invention is reserved. Although a very narrow claim may be presented herein, it should be recognized the scope of this invention is much broader than presented by the claim(s). Broader claims may be submitted in an application that claims the benefit of priority from this application.