Patent Publication Number: US-2023146842-A1

Title: Bi-directional wellhead annulus packoff with integral seal and hanger lockdown ring

Description:
BACKGROUND 
     1. Field of Invention 
     This disclosure relates generally to oilfield equipment and more particularly to a bi-directional wellhead annulus packoff and an associated method for energizing and de-energizing the wellhead annulus packoff. 
     2. Description of the Prior Art 
     Hangers may be configured with an external lockdown ring that is located above or below a wellhead annulus packoff. The wellhead annulus packoff can be locked down below the wellhead annulus packoff. However, such a configuration may create a debris pocket for accumulation of matter therein. A debris pocket can impede an ability of the lockdown ring to engage in a housing or hanger. Further, hangers may be configured with an external lockdown ring above the wellhead annulus packoff with some advantages, such as to allow for a debris pocket below the wellhead annulus packoff to accommodate debris. This, however, transfers a hanger lockdown load through the wellhead annulus packoff, which can cause issues for seal components in the wellhead annulus packoff. The wellhead annulus packoff can be locked independently to a neck of the hanger to prevent shuttling relative to the hanger. The timing and mechanism may be an issue while setting the wellhead annulus packoff, and particularly setting a seal lockdown ring and a hanger lockdown ring, in an annular envelop between the hanger neck and a wellhead housing bore. 
     SUMMARY 
     In at least one embodiment, a method to be used for energizing a wellhead annulus packoff is disclosed. The method includes providing at least one seal element, a seal lockdown energizing ring, a hanger lockdown energizing ring, a seal lockdown ring, and a hanger lockdown ring as seal components for the wellhead annulus packoff. The method also includes providing one or more mechanical conditional operators adapted to disengage during energizing of the wellhead annulus packoff. A further feature of the method includes enabling a first energizing force to cause, through the seal lockdown energizing ring, the at least one seal element and the seal lockdown ring to be energized. The method also includes enabling a second energizing force to cause, through the hanger lockdown energizing ring, the hanger lockdown ring to be energized. 
     In at least one embodiment, a further method to be used for de-energizing a wellhead annulus packoff is disclosed. The method is applied to the wellhead annulus packoff that includes at least one seal element, a seal lockdown energizing ring, a hanger lockdown energizing ring, a seal lockdown ring, a hanger lockdown ring, and one or more mechanical conditional operators in a disengaged state with the wellhead annulus packoff in a fully energized stage. The method includes enabling a first de-energizing force through the hanger lockdown energizing ring. The first de-energizing force is to cause the hanger lockdown ring to be de-energized. A further step in the method is for enabling a second de-energizing force through the seal lockdown energizing ring. The second de-energizing force is to cause the at least one seal element and the seal lockdown ring to be de-energized. 
     In at least one embodiment, a wellhead annulus packoff is disclosed. The wellhead annulus packoff includes at least one seal element, a hanger lockdown ring, a seal lockdown ring, and one or more mechanical conditional operators, where the at least one seal element adapted to be energized with a first energizing force and with the one or more mechanical conditional operators being engaged, where the seal lockdown ring is adapted to be energized with the first energizing force and with the one or more mechanical conditional operators being disengaged, and where the hanger lockdown ring is adapted to be energized with a second energizing force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments in accordance with the present disclosure will be described with reference to the drawings, in which: 
         FIG.  1 A  illustrates a cross-sectional view of a wellhead annulus packoff, in accordance to at least one embodiment. 
         FIGS.  1 B,  1 C, and  1 D  illustrate perspective views of a seal lockdown energizing ring associated with an upper seal energizing ring to be installed with a wellhead annulus packoff, in accordance to at least one embodiment. 
         FIG.  1 E  illustrates a further cross-sectional view of a wellhead annulus packoff, in accordance to at least one embodiment. 
         FIG.  2    illustrates a cross-sectional view of a landed wellhead annulus packoff, in accordance to at least one embodiment. 
         FIG.  3    illustrates a cross-sectional view of a wellhead annulus packoff in a first stage of a partly energized state, in accordance to at least one embodiment. 
         FIG.  4    illustrates a cross-sectional view of a wellhead annulus packoff in a second stage of a partly energized state, in accordance to at least one embodiment. 
         FIG.  5    illustrates a cross-sectional view of a wellhead annulus packoff in a third stage of a partly energized state, in accordance to at least one embodiment. 
         FIG.  6    illustrates a cross-sectional view of a wellhead annulus packoff in a fully energized state, in accordance to at least one embodiment. 
         FIG.  7    illustrates a cross-sectional view of a wellhead annulus packoff in a first stage of a partly de-energized state, in accordance to at least one embodiment. 
         FIG.  8    illustrates a cross-sectional view of a part of a wellhead annulus packoff in a second stage of a partly de-energized state, in accordance to at least one embodiment. 
         FIG.  9    illustrates a cross-sectional view of a part of a wellhead annulus packoff in a third stage of a partly de-energized state, in accordance to at least one embodiment. 
         FIG.  10    illustrates a cross-sectional view of a part of a wellhead annulus packoff in a fully de-energized state, in accordance to at least one embodiment. 
         FIG.  11    illustrates a cross-sectional view of a part of a wellhead annulus packoff in a removal stage, in accordance to at least one embodiment. 
         FIG.  12 A  is a flowchart illustrating a method for energizing in a wellhead annulus packoff, in accordance to at least one embodiment. 
         FIG.  12 B  is a flowchart illustrating a further method for de-energizing in a wellhead annulus packoff, in accordance to at least one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, various embodiments will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the embodiments may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the embodiment being described. 
     Various other functions can be implemented within the various embodiments as well as discussed and suggested elsewhere herein. In at least an aspect, the present disclosure is to a system and a method for a wellhead annulus packoff, in accordance to at least one embodiment. 
     In at least one embodiment, a wellhead annulus packoff that embodies a single trip bi-directional and integral seal with a hanger lockdown ring is disclosed. The single trip is in reference to seal components being run and installed in a single operation. Such a single trip may use a first energizing force for energizing a seal element and a seal lockdown ring and may use a second energizing force to energize a hanger lockdown ring. The single trip, therefore, may include two setting strokes, representing the two energizing forces, in a single operation. The two energizing forces are applied to both energize and retain the at least one seal element and the lockdown rings in an installed position. 
     In at least one embodiment, such a wellhead annulus packoff simplifies operational tooling required to set or energize a wellhead annulus packoff. The adaption discussed herein also allows the at least one seal element and hanger to be locked down from above the seal element and allows for improved debris tolerance and installation reliability for a wellhead annulus packoff. In a commercial setting, the adaption enables simultaneous setting and locking of a seal, in place, in a single operation. For example, the present adaption is able to engage both, the seal element and the seal lockdown ring in a single operation, without using wickers. In at least one embodiment, engagement and energizing are interchangeably used herein unless otherwise indicated, such as by an engagement feature first followed by an energizing feature. 
     In at least one embodiment, a wellhead annulus packoff herein is a bi-directional metal-to-metal (MS) annulus seal that includes two annular seals elements that isolate an annular space between a wellhead housing and a hanger, such as the neck of a hanger. At least one MS seal forms an annulus barrier between a volume above and a volume below within the annular space. Further, at least one seal element may be stacked in series to allow for a test volume between the at least one seal element to be formed for an external well barrier integrity testing. 
     In at least one embodiment, the wellhead annulus packoff is also referred to as a seal that may be characterized in two body portions. A lower seal body includes at least one seal element and an upper seal body that includes a seal lockdown ring, a seal lockdown energizing ring, a hanger lockdown ring, and a hanger lockdown energizing ring. The lockdown rings of the upper seal body represents a lockdown ring retention mechanism to lock the upper seal body to the neck of the hanger and to lock the hanger to the housing. This is so that a hanger-to-housing load may be transferred to the housing. The upper seal body may engage teeth of the seal lockdown ring into a matching lockdown profile in the hanger neck. 
     A mechanical conditional operator, such as a shear pin, a shear ring, a buckling member, a tensile coupon, or a spring-loaded member allows a setting or energizing force to be transferred through the upper seal body into the lower seal body to energize the at least one seal element. As part of the seal element being energized, the mechanical conditional operator changes the load path to set or energize the seal lockdown ring. For example, the mechanical conditional operator is adapted to disengage, such as by a change to its state or by shearing. Changes in state or shearing may include changes in a shape by collapsing, by buckling or by stressing or tensing. As such, when engaged, there may be a first load path through a mechanical conditional operator, but when disengaged, there may be a second load path through other seal components. 
     The at least one seal element forms an integrated seal. Once the at least one seal element is energized in place, a further feature herein is to energize other seal components of the wellhead annulus packoff by setting or energizing an external or a hanger lockdown ring to lock the hanger in the wellhead housing. In at least one embodiment, such an adaptation or configuration allows for vastly improved debris tolerance, because a debris pocket can be formed below the wellhead annular packoff, which can accommodate the debris. 
       FIG.  1 A  illustrates a cross-sectional view  100  of a wellhead annulus packoff  102 , in accordance to at least one embodiment. The wellhead annulus packoff  102  includes at least one seal element, such as a lower seal energizing ring  120  and a seal element  114 . The wellhead annulus packoff  102  includes a seal lockdown energizing ring  108 , a hanger lockdown energizing ring  104 , a seal lockdown ring  112 , and a hanger lockdown ring  106 . Further, the at least one seal element may be associated with one or more mechanical conditional operators  116 A,  118 B,  122 . 
     The one or more mechanical conditional operators  116 A,  118 B,  122  are adapted to disengage following energizing of the at least one seal element and prior to energizing of the seal lockdown ring, using a first energizing force applied through the seal lockdown energizing ring  108 . For example, when the mechanical conditional operator is a shear ring or a shear pin, the shear ring or shear pin is adapted to shear upon a first energizing force reaching a certain load. Further, the hanger lockdown ring  106  is adapted to be energized using a second energizing force through the hanger lockdown energizing ring  104 , once the seal lockdown ring has been energized. 
       FIG.  1 A  also illustrates transfer mechanisms  116 B,  118 A and mechanical conditional operators  116 A,  118 B,  122  that may be provided in determined sections  116 ,  118 ,  124  of the wellhead annulus packoff  102 . The transfer mechanisms  116 B,  118 A may be associated with the upper seal energizing ring  110  and the lower seal energizing ring  120 . In at least one embodiment, a transfer mechanism may be a threaded fastener, a segmented ring, or a split C-ring. The transfer mechanisms  116 B,  118 A can enable shoulders or surfaces in the provided sections  116 ,  118  of wellhead annulus packoff  102 . Such shoulders or surfaces are so that at least one seal component of the wellhead annulus packoff  102  may be lifted from an annular space during de-energizing of the wellhead annulus packoff  102 . 
       FIGS.  1 B,  1 C, and  1 D  illustrate perspective views  130 ,  140 ,  150  of a seal lockdown energizing ring associated with an upper seal energizing ring to be installed with a wellhead annulus packoff, in accordance to at least one embodiment. The views illustrated throughout herein are not to scale as is understood by a person of ordinary skill. In  FIG.  1 B , each of the seal lockdown energizing ring  132  and the upper seal energizing ring  134  are semi-circular members. Each semi-circular member is associated together and then the two associated semi-circular members are brought together as illustrated in  FIG.  1 C . 
       FIG.  1 A  therefore illustrates a wellhead annulus packoff that includes at least one seal element, a seal lockdown energizing ring, a hanger lockdown energizing ring, a seal lockdown ring, a hanger lockdown ring, and one or more mechanical conditional operators. The one or more mechanical conditional operators  116 A,  118 B,  122  are adapted to disengage during energizing of the wellhead annulus packoff using a first energizing force applied through the seal lockdown energizing ring. Then, a second energizing force may be applied through the hanger lockdown energizing ring for energizing of at least the hanger lockdown ring  106 . 
     In  FIG.  1 B , the seal lockdown energizing ring  132  is illustrated as being associated with the upper seal energizing ring  134  via a ridge  134 A that fits within railings  132 C, D defined inside fingers  132 A, B of the seal lockdown energizing ring  132 . The reference to the seal lockdown energizing ring  132  and the upper seal energizing ring  134  here is understood to be made to the semi-circular members where each semi-circular member undergoes a similar association. In other Figures, the reference to the seal lockdown energizing ring  132  and the upper seal energizing ring  132  will be understood to be a reference to the entire ring with the semi-circular members forming a ring, unless otherwise described. 
     The association of the seal lockdown energizing ring  132  and the upper seal energizing ring  134  (the semi-circular members of such rings) here is understood to be so that the ridge  134 A caught within the railings  132 A,  132 B may be used to lift the upper seal energizing ring during retrieval of the wellhead annulus packoff.  FIG.  1 B  also illustrates that the seal lockdown energizing ring  132  and the upper seal energizing ring  134  include through holes  132 E,  134 B which may be used for transfer mechanisms and for mechanical conditional operators. 
       FIG.  1 C  illustrates forming the middle and the upper seal energizing rings. Particularly, once each of semi-circular members of the seal lockdown energizing ring  142  and the upper seal energizing ring  144  are associated together, they are rotated  146  relative to each other, so that the semi-circular members of the seal lockdown energizing ring  142  and the upper seal energizing ring  144  are aligned one over the other.  FIG.  1 C  also illustrates that the upper seal energizing ring  144  includes tracks  144 A,  144 B for a transfer mechanism and/or a mechanical conditional operator. For example, the tracks may include a retainer ring that may enable the seal element to be held with the upper seal energizing ring. 
     The transfer mechanism, therefore, holds two or more seal components together and helps in retrieval of such seal components. However, the transfer mechanism may not transfer energizing forces during energizing. The mechanical conditional operators may transfer portions of the energizing forces through one or more seal components. In at least one embodiment, some seal components may not have association with a mechanical conditional operator but may only have a transfer mechanisms associated therewith. For example, other than a seal lockdown energizing ring and an upper seal energizing ring, some seal components may only have a transfer mechanisms associated therewith. 
       FIG.  1 C , along with  FIG.  1 D , also illustrates a locking feature for the semi-circular members, so that, once associated together with the respective halves while siting one or over the other, the seal lockdown energizing ring  152  and the upper seal energizing ring  154  may be rotated relative to each other so that a split or seam  152 A of the seal lockdown energizing ring  152  is 90 degree or another angle offset from a split or seam  154 A of the upper seal energizing ring  154 . This allows the seal lockdown energizing ring  152  and the upper seal energizing ring  154  to be associated together but also allows the seal lockdown energizing ring  152  and the upper seal energizing ring  154  to be locked together for landing purposes into an annular space. The offset of the splits or seams  152 A,  154 A ensures that the seal lockdown energizing ring  152  and the upper seal energizing ring  154  do not come apart. 
     In at least one embodiment, the association together of the seal lockdown energizing ring  152  and the upper seal energizing ring  154  also allows relative movement between these two parts. Such relative movement (or stroke) may be limited by a gap between a surface of the ridge  136 A and a corresponding mating surface  136 B. As such, these two parts may be held together, but can move by a predetermined amount that may be limited by a gap defined between the two interfacing surfaces  136 A,  136 B. In at least one embodiment, a state of the mechanical condition operator is related to a capability of a relative movement enabled between the seal lockdown energizing ring  152  and the upper seal energizing ring  154 . For example, when a shear pin that associates together the seal lockdown energizing ring  152  and the upper seal energizing ring  154 , is not sheared, there is no relative movement allowed between these two seal components and hence applied load from an energizing force is transferred through the seal. When the shear pin has sheared, these two seal components can move relative to each other and the applied load to a seal lockdown energizing ring  152 , from the energizing force, causes at least the seal lockdown ring  186  to be energized. 
       FIG.  1 E  illustrates a further cross-sectional view  170  of a wellhead annulus packoff, in accordance to at least one embodiment.  FIG.  1 E  illustrates at least one seal element  182  provided above and below other seal components. For example, the seal lockdown energizing ring  172  and the upper seal energizing ring  174  are above the seal element  182 , while the lower seal energizing ring  184  is below the seal element  182 . Further,  FIG.  1 E  illustrates that the through holes (such as, through holes  156  in  FIG.  1 D ) may be aligned for the seal lockdown energizing ring  172  and the upper seal energizing ring  174 . The alignment of the through holes allows shearing pins or other mechanical conditional operators  176  to be provided between the seal lockdown energizing ring  172  and the upper seal energizing ring  174 . This may be a further locking features for the seal lockdown energizing ring  172  and the upper seal energizing ring  174  to be landed together in position. 
       FIG.  1 E  also illustrates further that mechanical conditional operators  176 ,  178 ,  180  may be provided between the seal lockdown energizing ring  172  and the upper seal energizing ring  174 , and separately between the upper seal energizing ring  174  and the seal element  182 . The mechanical conditional operators  176 ,  178 ,  180  may be provided to prevent relative motion between seal components during engagement, such as preventing relative movement between the upper seal energizing ring  174  and the seal element  182  during landing; but may be provided also for enabling relative movement after disengagement so an applied energizing force may transfer elsewhere into a seal. 
       FIG.  2    illustrates a cross-sectional view  200  of a landed wellhead annulus packoff  200 A, in accordance to at least one embodiment. The wellhead annulus packoff  200 A is landed in an annular or annulus space  202  and on a shoulder  206 A of the hanger  206 , for instance. Particularly, a bottom surface  220 A of a lower seal energizing ring  220  may be abutting a shoulder  206 A of the hanger  206 . In at least one embodiment, a first energizing force (downward component of the reference arrow  208 A) may be enabled to cause, through a seal lockdown energizing ring  210 , the at least one seal element, such as seal element  216  and a lower seal energizing ring  220 , along with the seal lockdown ring  218 , to be energized. 
     In at least one embodiment, a second energizing force (downward component of the reference arrow  208 B) may be enabled to cause, through a hanger lockdown energizing ring  224 , a hanger lockdown ring  222 , to be energized. The first energizing force  208 A may be applied as a single continuous stroke or force through the stages illustrated in  FIGS.  3  to  5   , with  FIG.  6    illustration the second energizing force applied for energizing the hanger lockdown ring. The energizing stages are therefore illustrated at least via the stages in  FIGS.  3  to  6   , following the landing illustrated in  FIG.  2   , where a fully energized wellhead annulus packoff is illustrated in  FIG.  6   . 
     For removal of the wellhead annulus packoff  200 A, a first de-energizing force (upward component of the reference arrow  208 B) may be applied to cause the hanger lockdown ring  222  to be de-energized. Still further, a second de-energizing force or pulling force (upward component of the reference arrow  208 A) may be provided to the seal lockdown energizing ring  210  during removal of the wellhead annulus packoff  200 A, in accordance to at least one embodiment. At least the second de-energizing force (upward component  208 A) is applied through the stages illustrated in  FIGS.  8  to  11   , with the first de-energizing force (upward component  208 B) applied as illustrated in  FIG.  7   . The de-energizing stages are therefore illustrated at least via the stages in  FIGS.  7  to  10   , with  FIG.  11    illustrating a removal stage for the wellhead annulus packoff  200 A. 
     In at least one embodiment, the lower seal energizing ring  220  is adapted to sit on a shoulder  206 A of the hanger  206 . Further, a seal element  216  includes legs, such as an outer bottom leg  216 C, that may be subsequently energized by the lower seal energizing ring  220 . Further, the lower seal energizing ring  220  may include a straight surface or profile  220 B or a toothed surface or profile to engage with a mating profile provided for a hanger  206 . Furthermore a seal element  216  may include inner legs  216 D that are distinct from the outer bottom leg. In at least one embodiment, the inner legs  216 D provided sealing against the hanger  206  when the seal element  216  moves down relative to the hanger  206 . 
       FIG.  2    also illustrates that one or more mechanical conditional operators  216 A, B are provided with at least the seal element  216 . The one or more mechanical conditional operators  214 A,  216 A,  216 B may be associated between the seal element  216  and the upper seal energizing ring  214  and/or associated between the seal element  216  and the lower seal energizing ring  220 . Further, the one or more mechanical conditional operators  214 A,  216 A,  216 B are adapted to disengage or change state during energizing of at least one seal element of the wellhead annulus packoff, such as energizing of the lower seal energizing ring  220  and of the seal element  216 . 
     In at least one embodiment, the seal lockdown ring  218  is illustrated with a toothed surface or profile  218 A to mate with a matching profile  206 B provided for a hanger  206 . Similarly, the hanger lockdown ring  222  may include a toothed surface or profile  222 A to mate with a matching profile  204 A provided for a housing  204 . The first energizing force  208 A transfers  212  through the seal lockdown energizing ring  210 , the mechanical conditional operator  214 A, and the upper seal energizing ring  214 . Subsequently, a seal element  216  receives the first energizing force  208 A from the upper seal energizing ring  214 . 
     In at least one embodiment, part of the first energizing force  208 A is transferred via a mechanical conditional operator ( 214 A or  176 ), such as a shear pin. The conditional operator  214 A or  176  may change state once the seal element  216 ;  182  is fully energized, and then allows the seal lockdown ring  218  to be set or energized as influenced in part by the second stage  208 A of a continuous first energizing force or stroke, which is also illustrated in  FIG.  5   .  FIG.  2    illustrates that such transfers  212  of energizing force may occur via contacting surfaces between the seal lockdown energizing ring  210 , the seal lockdown ring  218  and the upper seal energizing ring  214 . As such, unless otherwise stated, gaps illustrated between such seal components are not present in an actual physical wellhead annulus packoff  200 A. In at least one embodiment, such features enable the bi-directional wellhead annulus packoff with an associated method for energizing using a single operation having a first energizing force applied as a single continuous stroke or force, followed by a second energizing force applied in a first direction to energize a wellhead annulus packoff. An associated method is provided for de-energizing that may be applied in an opposite direction, than the first direction, to de-energize and remove such a wellhead annulus packoff. 
       FIG.  3    illustrates a cross-sectional view  300  of a wellhead annulus packoff  300 A in a first stage of a partly energized state, in accordance to at least one embodiment. The first energizing force  322  may be introduced to the seal lockdown energizing ring  302 . The first energizing force  322  is a continuous setting or energizing stroke or force applied from this stage till at least the seal lockdown ring  304  is energized (such as, by the stage of  FIG.  5   ). The first energizing force  322 , therefore, transfers to the upper seal energizing ring  306  and to the seal element  312 , through a mechanical conditional operator that then shears and allows the first energizing force  322  to energize the seal lockdown ring  304  (as in  FIG.  5   ). 
     The first energizing force  322  causes the at least one seal element  312  to be energized first, with the lower seal energizing ring  316 , by the first energizing force passing through the seal via one or more transfer mechanisms. This is part of a first stage of energizing of the wellhead annulus packoff  300 A. Once the seal element  312  is fully energized (which is also illustrated in  FIG.  4   ), then the mechanical conditional operator  324  changes state, such as by shearing, which allows relative movement between the seal lockdown energizing ring  302  and the upper seal energizing ring  306 . Such relative movement allows the first energizing force on the seal lockdown energizing ring  302 , which is continued in the first stage after the seal element  312  is fully energized, to also energize the seal lockdown ring  304 . 
     The lower seal energizing ring  316  may be associated with a mechanical conditional operator  314 B that is also associated with the seal element  312 . In the first stage of the partly energized state, the mechanical conditional operator  314 B associated between the lower seal energizing ring  316  and the seal element  312  may be caused to shear or change state in other ways so that one of the at least one seal element may slide against the lower seal energizing ring  316  during energizing of the wellhead annulus packoff  300 A. In  FIG.  3   , the mechanical conditional operator  314 B is illustrated as sheared as compared to its initial state  216 A, when landed, in  FIG.  2   . 
     In at least one embodiment, the shearing of the mechanical conditional operator  314 B enables a slot or space  312 B to be formed. Further, a surface or shoulder  312 C of the seal element  312  is exposed and may be used during de-energizing to allow the seal element  312  support a transfer mechanism  314 A during retrieval of the lower seal energizing ring  316  by a pulling force that transfers to the seal element as discussed in at least in  FIG.  10   .  FIG.  3    also illustrates a leg  312 A of the seal element  312  that is driven against the lower seal energizing ring  316  to energize seal leg  312 A against the housing. 
     In at least one embodiment, inner legs  312 E of a seal element  312  form a seal against a neck of a hanger as the seal element  312  moves down during energizing. In a landed position, such as illustrated in  FIG.  2   , such inner legs  312 E have an internal diameter that is less than an outer diameter of the neck of the hanger, at location in which the sealing is enabled. A relative movement of the inner legs  312 E over the neck of the hanger may cause interference. The interference may energize the inner seals  312 E with the hanger. Also, the top and bottom inner legs  312 E may have different internal diameters, which may interface with different hanger outer diameters at their respective locations. In its energized position, a void  226  (in  FIG.  2   ) that was previously above the lower seal energizing ring  316  and the seal element  312  is closed. 
       FIG.  3    also illustrates that a further void  318  between the seal element and an upper seal energizing ring  306  remains so that the first energizing force  322  continues to be provided. Particularly, a different mechanical conditional operator  312 D that is associated between the upper seal energizing ring  306  and the seal element  312  may be intact and yet to be sheared or to change state in other ways so that another one of the at least one seal element may slide against the upper seal energizing ring  306  during energizing of the wellhead annulus packoff  300 A. Still other voids  310 ,  320  may remain at this first stage of energizing of the wellhead annulus packoff  300 A. 
     In at least one embodiment,  FIG.  3    illustrates that the seal element  312  can be energized against a lower seal energizing ring  316  with the first energizing force  322  applied through at least a first one  314 B of one or more mechanical conditional operators that has sheared or changed state. In at least one embodiment,  FIG.  3    also illustrates that the upper seal energizing ring  306  can transfer at least one part of the first energizing force to the seal element  312  so that the seal element  312  energizes against a lower seal energizing ring  316  in the first stage of energizing of the wellhead annulus packoff. 
       FIG.  4    illustrates a cross-sectional view  400  of a wellhead annulus packoff  400 A in a second stage of a partly energized state, in accordance to at least one embodiment. As the first energizing force  402  is continued at the seal lockdown energizing ring  404  for the energizing of the wellhead annulus packoff  400 A, the first energizing force  402  causes the upper seal energizing ring  408  to shear or change state of the mechanical conditional operator  408 A (previously noted as  312 D in  FIG.  3   ) that is associated between the upper seal energizing ring  408  and the seal element  406 .  FIG.  4    also illustrates residual grooves  420 A,  420 B after shearing and which may contain a sheared piece of the mechanical conditional operator. Further, presence of such residual grooves  420 A,  420 B represents a change in state of the mechanical conditional operator  408 A and  408 D. In at least one embodiment, at least shearing of a shear pin may result in residual grooves  420 A,  420 B on the seal element. 
     Then, the upper seal energizing ring  408  closes a previously indicated void ( 318  in  FIG.  3   ) and enables a space or slot  414  for a shoulder  410  for a transfer mechanism  408 B to engage during retrieval of the wellhead annulus packoff  400 A, which is discussed further in  FIG.  9   . With support from underneath, provided by the energized lower seal energizing ring and the seal element, the upper seal energizing ring  408  may energize the top outer leg  406 A, along with the seal element  406 , by the first energizing force  402 . 
       FIG.  4    also illustrates that the wellhead annulus packoff  400 A includes the seal element having an upper leg  406 A and includes the seal lockdown ring  418 . There may be further voids  416 A,  416 B that remain to be addressed by the upper seal components being energizing by the first energizing force  402  that continues to be applied through the seal lockdown energizing ring  404 . In at least one embodiment, the lower seal components (such as, the lower seal energizing ring and the seal element) being energized supports energizing of the upper seal components (such as, the upper seal energizing ring, the seal lockdown energizing ring, the seal lockdown ring, and the hanger lockdown ring). 
     In at least one embodiment,  FIG.  4    illustrates that the upper seal energizing ring  408  can energize the seal element  406  with the first energizing force applied after a second one  408 A of the one or more mechanical conditional operators has sheared or changed state. In at least one embodiment, the seal lockdown energizing ring  404  has transferred at least one part of the first energizing force to the upper seal energizing ring  408  so that the upper seal energizing ring  408  energizes a seal element  406  in the second stage of energizing of the wellhead annulus packoff. 
     In at least one embodiment, a third one  408 C of the one or more mechanical conditional operators, also illustrated as reference numeral  176  in  FIG.  1 E , has not sheared yet and allows the first energizing force to be transferred through the seal lockdown energizing ring  404  and through the upper seal energizing ring  408 . In at least one embodiment, the top inner and outer legs of the seal element may be energized before the bottom inner and outer legs of the seal element are energized. In at least one embodiment, both the top and the bottom inner and outer legs of the seal element may be energized simultaneously. Therefore, an order of engagement of the upper and lower seal energizing rings may not be restrictive. For example, the top inner and outer legs of the seal element may be set or energized by the upper seal energizing ring, prior to the bottom inner and outer legs of the seal element being set or energized by the lower seal energizing ring. 
       FIG.  5    illustrates a cross-sectional view  500  of a wellhead annulus packoff  500 A in a third stage of a partly energized state, in accordance to at least one embodiment. As the single continuous stroke or force  502  is applied through the seal lockdown energizing ring  504 , the remaining voids in the upper seal components of the upper seal energizing ring  508 , the seal lockdown energizing ring  504 , the seal lockdown ring  506  close. In at least one embodiment, the seal lockdown ring  506  may be an outwards biased split C-ring. For example, the mechanical conditional operator  508 A (previously illustrated as reference numeral  176  in  FIG.  1 E  that had not sheared) is now sheared or has changed state (shear occurs when a shear pin is used as the mechanical conditional operator  508 A). Once sheared, relative movement between the seal lockdown energizing ring  504  and the upper seal energizing ring  508  occurs. 
     Particularly, with the lower seal components being energized and offering support from underneath to the upper seal components, the first energizing force  502  cannot cause further movements to the lower seal components and instead causes the seal lockdown energizing ring  504  to settle between the seal lockdown ring  506  and the upper seal energizing ring  508 . A finger  504 A of the seal lockdown energizing ring may energize the seal lockdown ring  506  with support from the upper seal energizing ring  508  and another finger  504 B of the seal lockdown energizing ring  504 . A finger  504 A of the seal lockdown energizing ring  504  causes inward radial movement (such as, towards an axis of a wellbore) of the seal lockdown ring  506 . This allows the seal lockdown ring  506  to be driven towards engagement with a matching profile on a neck of the hanger. The seal lockdown ring is made to sit within a matching profile of the hanger. 
       FIG.  6    illustrates a cross-sectional view  600  of a wellhead annulus packoff  600 A in a fully energized state, in accordance to at least one embodiment.  FIG.  6    also illustrates that a second energizing force  602  may be applied, different from the first energizing force applied as a single continuous stroke or force to achieve different stages one to four of energizing, in  FIGS.  3  to  5   . The second energizing force  602  may be applied once the seal lockdown ring is energized and may be applied to a hanger lockdown energizing ring  604 . The second energizing force  602  causes at least the hanger lockdown ring  606  to be energized against a matching profile of the housing. The hanger lockdown ring  606  may be an inwards biased split C-ring. The hanger lockdown energizing ring  604  may cause outward radial movement (such as, away from an axis of a wellbore) of the hanger lockdown ring  606 . This allows the hanger lockdown ring  606  to be driven towards engagement with a matching profile on the housing. The wellhead annulus packoff  600 A is therefore in a fully energized state. 
       FIG.  7    illustrates a cross-sectional view  700  of a wellhead annulus packoff  700 A in a first stage of a partly de-energized state, in accordance to at least one embodiment. Initially a first de-energizing force  702  may be applied as a pulling force to the hanger lockdown energizing ring  704 . As the hanger lockdown energizing ring  704  has been pulled up, the hanger lockdown ring  706  releases and both these seal components may be removed. In at least one embodiment, removal of radial support, previously provided by a hanger lockdown energizing ring  704  to the hanger lockdown ring  706 , enables an inwards bias of the hanger lockdown ring  706  to activate thereby retracting away the hanger lockdown ring  706  from a matching profile in the housing. 
       FIG.  8    illustrates a cross-sectional view  800  of a part of a wellhead annulus packoff  800 A in a second stage of a partly de-energized state, in accordance to at least one embodiment. With the hanger lockdown energizing ring and the hanger lockdown ring removed (for illustrative purposes), a second de-energizing force  802  that is a single continuous de-energizing stroke or force may be applied through the seal lockdown energizing ring  804 . In at least one embodiment, the hanger lockdown energizing ring and the hanger lockdown ring are not fully removed, but in this stage, the hanger lock down ring and the hanger lockdown energizing ring will remain associated with the wellhead annulus packoff  800 A, but in the unenergized state. This at least causes a finger of the seal lockdown energizing ring  804  to release from against the seal lockdown ring  806 . The seal lockdown ring  806  may be released as a result. 
     The removal of radial support, previously provided by at least a finger of the seal lockdown energizing ring  804  to the seal lockdown ring  806  can cause an outwards bias of the seal lockdown ring  806  to activate and enables the seal lockdown ring  806  to retract away from a matching profile in the hanger. The second de-energizing force  802  also allows a flange of the upper seal energizing ring  810  to catch within a narrow neck between the fingers of the seal lockdown energizing ring in the area  808  illustrated in  FIG.  8   . Such a catch allows the second de-energizing force  802  to transfer to the upper seal energizing ring  810  to be pulled upwards for de-energizing the seal element  812 . Also illustrated is that a shoulder  810 A of the upper seal energizing ring  810  provides support to lift the seal lockdown ring  806  out of the annular space. 
       FIG.  9    illustrates a cross-sectional view  900  of a part of a wellhead annulus packoff  900 A in a third stage of a partly de-energized state, in accordance to at least one embodiment. As the second de-energizing force  902  is continuously applied via the seal lockdown energizing ring  904 , the second de-energizing force  902  is transferred in part to the upper seal energizing ring  906  so that it can support the seal lockdown ring  908  being removed and can also catch against a shoulder or surface of the seal element  910 . Particularly, a transfer mechanism  906 A engages the shoulder or surface of the seal element  910  after moving through a slot or space  910 A enabled by a mechanical conditional operator. With the seal element  910  caught on the transfer mechanism  906 A, the seal element  910  is caused to be removed by the same second de-energizing force  902  transferred through the seal element  910 . 
       FIG.  10    illustrates a cross-sectional view  1000  of a part of a wellhead annulus packoff  1000 A in a fully de-energized state, in accordance to at least one embodiment. As the second de-energizing force  1002  continues to be applied and transferred through the seal element  1006 , a leg  1006 B of the seal element  1006  releases from against the lower seal energizing ring  1004 . The seal element  1006  being removed also causes a shoulder  1006 A of the seal element  1006  to catch on a transfer mechanism  1004 A of the lower seal energizing ring  1004 . Such a catch causes the lower seal energizing ring  1004  to be removed with the seal element  1006 . The wellhead annulus packoff  1000 A is in a fully de-energized state. 
       FIG.  11    illustrates a cross-sectional view  1100  of a part of a wellhead annulus packoff  1100 A in a removal stage, in accordance to at least one embodiment.  FIG.  11    illustrates that, as the second de-energizing force is continued, the wellhead annulus packoff  1100 A is removed from the shoulder  1102  of the hanger and from the annular space  1104  between the hanger and the housing. The lower seal energizing ring provides the lower most seal component to support the remaining seal components being removed, but each seal component is associated with a prior seal component via shoulders, surfaces, or transfer mechanisms, as discussed. 
       FIG.  12 A  is a flowchart illustrating a method  1200  for energizing in a wellhead annulus packoff, in accordance to at least one embodiment. The method  1200  includes providing ( 1202 ) at least one seal element, a seal lockdown energizing ring, a hanger lockdown energizing ring, a seal lockdown ring, and a hanger lockdown ring for a wellhead annulus packoff. The method includes providing ( 1204 ) one or more mechanical conditional operators that are adapted to disengage during energizing of the at least one seal element of the wellhead annulus packoff. A verification step may be provided to verify that the wellhead annulus packoff is properly landed. A step  1204  or other steps may be repeated if the verification fails. A further step  1206  may be performed otherwise. 
     The method  1200  includes enabling ( 1206 ) a first energizing force to cause, through the seal lockdown energizing ring, the at least one seal element to be energized. A verification step  1208  is performed to verify that the seal element is engaged or energized, otherwise the prior enabling ( 1206 ) step may be repeated. Upon successful verification in step  1208 , another step in the method  1200  includes causing ( 1210 ) one or more mechanical conditional operators to disengage, such as to become sheared or to change state, as the first energizing force is continued. 
     With the one or more mechanical conditional operators disengaged, such as be sheared or change in state, a further step in the method  1200  includes enabling ( 1212 ) the first energizing force to continue further to cause, through the seal lockdown energizing ring, the seal lockdown ring to be energized. A verification step  1214  may occur to ensure that the seal lockdown ring is energized. Upon positive verification, step  1216  may occur; otherwise, step  1212  may be repeated. 
     The method  1200  includes enabling ( 1216 ) a second energizing force to cause, through the hanger lockdown energizing ring, the hanger lockdown ring to be energized. In at least one embodiment, one or more of the steps in the method  1200  may be performed in a combined manner with a built-in verification, such as steps  1206  to  1212  may be performed together with the verification step  1208  as a single continue stroke using the first energizing force and using load limits mechanically built into the one or more mechanical conditional operators. 
     The method  1200  may include further steps or sub-steps for associating the one or more mechanical conditional operators with the at least one seal element or the seal lockdown energizing ring. The method  1200  may include further steps or sub-steps for causing the one or more mechanical conditional operators to shear or change state as part of the disengagement during energizing of the wellhead annulus packoff. 
     The method  1200  may include further steps or sub-steps for enabling the first energizing force to be applied as a single continuous force to the seal lockdown energizing ring. Further, a first part of the single continuous force causes the at least one seal element to be energized. A second part of the single continuous force causes the one or more mechanical conditional operators adapted to be disengaged. A third part of the single continuous force causes the one or more mechanical conditional operators adapted to disengage causes the seal lockdown ring to be energized. 
     The method  1200  may include further steps or sub-steps for enabling, using the first energizing force, the at least one seal element (such as, the bottom inner leg, top inner leg, and bottom outer leg of the seal element) to be energized through a first relative movement against the lower seal energizing ring. The first relative movement may be enabled by a disengagement of a first one of the one or more mechanical conditional operators. The method  1200  may include further steps or sub-steps for enabling, using the first energizing force, the at least one seal element to be energized through a second relative movement against an upper seal energizing ring. The second relative movement may be enabled by a disengagement of a second one of the one or more mechanical conditional operators. 
     The method  1200  may include further steps or sub-steps for enabling one of the one or more mechanical conditional operators to transfer at least one part of the first energizing force, through an upper seal energizing ring, to the at least one seal element. The at least one seal element can energize with a lower seal energizing ring in a first stage of the energizing of the wellhead annulus packoff. The method  1200  may include further steps or sub-steps for enabling the seal lockdown energizing ring to transfer at least another part of the first energizing force to an upper seal energizing ring, with the one of the one or more mechanical conditional operators being disengaged. The at least one seal element can energize with the upper seal energizing ring in a second stage of the energizing of the wellhead annulus packoff. 
     The method  1200  may include further steps or sub-steps for enabling, using the first energizing force, the upper seal energizing ring to energize with the at least one seal element and with the seal lockdown ring in a third stage of the energizing of the wellhead annulus packoff. The method  1200  may include further steps or sub-steps for enabling, using the second energizing force, the hanger lockdown energizing ring to energize with the hanger lockdown ring and with the seal lockdown energizing ring to provide a fully energized stage of the wellhead annulus packoff. 
       FIG.  12 B  is a flowchart illustrating a further method  1250  for de-energizing in a wellhead annulus packoff, in accordance to at least one embodiment. The method  1250  is applicable to a wellhead annulus packoff that is in a fully energized stage with the one or more mechanical conditional operators being in a disengaged state. The wellhead annulus packoff includes at least one seal element, a seal lockdown energizing ring, a hanger lockdown energizing ring, a seal lockdown ring, a hanger lockdown ring, and the one or more mechanical conditional operators, with the one or more mechanical conditional operators being in the disengaged state with the wellhead annulus packoff in a fully energized stage. 
     When provided ( 1252 ) with such a wellhead annulus packoff that is in a fully energized stage, the method includes enabling ( 1254 ) a first de-energizing force through the hanger lockdown energizing ring. The first de-energizing force can cause the hanger lockdown ring to be de-energized. A verification step  1256  verifies that the hanger lockdown ring is de-energized. The prior enabling step  1254  may be otherwise repeated. Upon successful verification, a further enabling ( 1258 ) step may be performed for a second de-energizing force through the seal lockdown energizing ring. The second de-energizing force can cause the seal lockdown ring to be de-energized and can cause the at least one seal element to be de-energized. 
     The method  1250  may include further steps or sub-steps for enabling, using first shoulders or surfaces, transfer of the second de-energizing force from the seal lockdown energizing ring to the upper seal energizing ring. The method  1250  may include further steps or sub-steps for enabling, using second shoulders or surfaces, transfer of the second de-energizing force, from the upper seal energizing ring to the at least one seal element. Further, the method  1250  may include further steps or sub-steps for enabling, using third shoulders or surfaces, transfer of the second de-energizing force, from the seal element to a lower seal energizing ring so that the wellhead annulus packoff is de-energized. 
     It should be appreciated that embodiments herein may utilize one or more values that may be experimentally determined or correlated to certain performance characteristics based on operating conditions under similar or different conditions. The present disclosure described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the disclosure has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present disclosure disclosed herein and the scope of the appended claims. 
     While techniques herein may be subject to modifications and alternative constructions, these variations are within spirit of present disclosure. As such, certain illustrated embodiments are shown in drawings and have been described above in detail, but these are not limiting disclosure to specific form or forms disclosed; and instead, cover all modifications, alternative constructions, and equivalents falling within spirit and scope of disclosure, as defined in appended claims. 
     Terms such as a, an, the, and similar referents, in context of describing disclosed embodiments (especially in context of following claims), are understood to cover both singular and plural, unless otherwise indicated herein or clearly contradicted by context, and not as a definition of a term. Including, having, including, and containing are understood to be open-ended terms (meaning a phrase such as, including, but not limited to) unless otherwise noted. Connected, when unmodified and referring to physical connections, may be understood as partly or wholly contained within, attached to, or joined together, even if there is something intervening. 
     Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within range, unless otherwise indicated herein and each separate value is incorporated into specification as if it were individually recited herein. In at least one embodiment, use of a term, such as a set (for a set of items) or subset unless otherwise noted or contradicted by context, is understood to be nonempty collection including one or more members. Further, unless otherwise noted or contradicted by context, term subset of a corresponding set does not necessarily denote a proper subset of corresponding set, but subset and corresponding set may be equal. 
     Conjunctive language, such as phrases of form, at least one of A, B, and C, or at least one of A, B and C, unless specifically stated otherwise or otherwise clearly contradicted by context, is otherwise understood with context as used in general to present that an item, term, etc., may be either A or B or C, or any nonempty subset of set of A and B and C. In at least one embodiment of a set having three members, conjunctive phrases, such as at least one of A, B, and C and at least one of A, B and C refer to any of following sets: {A}, {B}, {C}, {A, B}, {A, C}, {B, C}, {A, B, C}. Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of A, at least one of B and at least one of C each to be present. In addition, unless otherwise noted or contradicted by context, terms such as plurality, indicates a state of being plural (such as, a plurality of items indicates multiple items). In at least one embodiment, a number of items in a plurality is at least two, but can be more when so indicated either explicitly or by context. Further, unless stated otherwise or otherwise clear from context, phrases such as based on means based at least in part on and not based solely on. 
     In at least one embodiment, even though the above discussion provides at least one embodiment having implementations of described techniques, other architectures may be used to implement described functionality, and are intended to be within scope of this disclosure. In addition, although specific responsibilities may be distributed to components and processes, they are defined above for purposes of discussion, and various functions and responsibilities might be distributed and divided in different ways, depending on circumstances. 
     In at least one embodiment, although subject matter has been described in language specific to structures and/or methods or processes, it is to be understood that subject matter claimed in appended claims is not limited to specific structures or methods described. Instead, specific structures or methods are disclosed as example forms of how a claim may be implemented. 
     From all the above, a person of ordinary skill would readily understand that the tool of the present disclosure provides numerous technical and commercial advantages, and can be used in a variety of applications. Various embodiments may be combined or modified based in part on the present disclosure, which is readily understood to support such combination and modifications to achieve the benefits described above.