Patent Publication Number: US-8978751-B2

Title: Method and apparatus for sealing a wellbore

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority to U.S. provisional patent application Ser. No. 61/450,965 filed on Mar. 9, 2011 and entitled “METHOD AND APPARATUS FOR SEALING A WELLBORE.” 
    
    
     BACKGROUND 
     The present disclosure relates generally to oilfield operations. More specifically, the present disclosure relates to techniques for sealing a wellbore. 
     Oilfield operations are typically performed to locate and gather valuable downhole fluids. Oil rigs are positioned at wellsites and downhole tools, such as drilling tools, are deployed into the ground to reach subsurface reservoirs. Once the downhole tools form a wellbore to reach a desired reservoir, casings may be cemented into place within the wellbore, and the wellbore completed to initiate production of fluids from the reservoir. Tubing or pipes are typically positioned in the wellbore to enable the passage of subsurface fluids to the surface. 
     Leakage of subsurface fluids may pose a significant environmental threat if released from the wellbore. Equipment, such as blow out preventers (BOPs), are often positioned about the wellbore to form a seal about pipes and to prevent leakage of fluid as it is brought to the surface. BOPs may employ rams and/or ram blocks that seal the wellbore. Some examples of ram BOPs and/or ram blocks are provided in U.S. Pat. Nos. 4,647,002, 6,173,770, 5,025,708, 7,051,989, 5,575,452, 6,374,925, 20080265188, U.S. Pat. No. 5,735,502, U.S. Pat. No. 5,897,094, U.S. Pat. No. 7,234,530 and 2009/0056132. The BOPs may be provided with various devices to seal various portions of the BOP as described, for example, in U.S. Pat. Nos. 4,508,311, 5,975,484, 6,857,634 and 6,955,357. Despite the development of sealing techniques, there remains a need to provide advanced techniques for sealing wellbores. 
     SUMMARY 
     The present disclosure relates to techniques for sealing a pipe of a wellbore. Inserts may be positioned in a seal assembly of carried by a pair of opposing ram blocks of a blowout preventer. The inserts have upper and lower bodies with a rib therebetween. The upper and lower bodies are provided with extended tips on a seal end thereof and tip receptacles on a leading face thereof. The extended tips are receivable in the tip receptacles of an adjacent insert to restrict extrusion of therebetween. The upper and lower bodies may also be provided with recesses and ledges for interlocking engagement and slidable movement between the inserts. Scallops may be provided along the tips to conform to various pipe diameters. 
     In another aspect, the disclosure relates to a seal assembly of a blowout preventer. The blowout preventer includes a pair of opposing ram blocks positionable about a pipe of a wellsite. The seal assembly includes a pair of seals carried by the pair of opposing ram blocks and a plurality of inserts. The inserts carried by the pair of seals and positionable about the pipe in an elliptical array. Each of the inserts having an upper body and a lower body with a rib therebetween. Each of the upper and lower bodies have an extended tip on a seal end thereof and a tip receptacle on a leading face thereof. The extended tips of the upper and lower bodies of each of the inserts are receivable in the tip receptacles of an adjacent one of the inserts whereby extrusion of the pair of seals between the inserts is restricted. 
     In yet another aspect, the disclosure relates to a blowout preventer for sealing a pipe of a wellsite. The blowout preventer includes a housing, a pair of opposing ram blocks positionable about a pipe of a wellsite, and a seal assembly. The seal assembly includes a pair of seals carried by the pair of opposing ram blocks and positionable in sealing engagement about the pipe and a plurality of inserts. The inserts are carried by the pair of seals and positionable about the pipe in an elliptical array. Each of the inserts have an upper body and a lower body with a rib therebetween. Each of the upper and lower bodies have an extended tip on a seal end thereof and a tip receptacle on a leading face thereof. The extended tips of the upper and lower bodies of each of the inserts are receivable in the tip receptacles of an adjacent one of the inserts whereby extrusion of the pair of seals between the inserts is restricted. 
     Finally, in yet another aspect, the disclosure relates to a method of sealing a pipe of a wellsite. The method involves providing a blowout preventer including a housing, a pair of opposing ram blocks positionable about the pipe, and a seal assembly. The seal assembly includes a pair of seals carried by the opposing ram blocks and a plurality of inserts. The carried by the seals. The inserts have an upper body and a lower body with a rib therebetween. Each of the upper and lower bodies has an extended tip on a seal end thereof and a tip receptacle on a leading face thereof. The method further involves positioning the inserts of the seal assembly about the pipe in an elliptical array by advancing the opposing ram blocks toward the pipe, and restricting extrusion of the pair of seals between the inserts by receiving the extended tips of the upper and lower bodies of each of the inserts in the tip receptacles of an adjacent one of the inserts. 
    
    
     
       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 technology herein, briefly summarized above, may be had by reference to the embodiments thereof that are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this technology and are, therefore, not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments. 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 view of an offshore wellsite having a BOP with a seal assembly therein according to the disclosure. 
         FIG. 2  is a schematic view of the BOP of  FIG. 1  having ram blocks with the seal assembly thereon. 
         FIGS. 3A and 3B  are schematic views of ram blocks with a seal assembly thereon in a retracted and sealed position, respectively. 
         FIGS. 4A-4C  are various schematic views of an insert of a seal assembly. 
         FIGS. 5A and 5B  are schematic views of a portion of a seal assembly having a gap and a reduced gap, respectively. 
         FIGS. 6A-6D  are various schematic views of various portions of a seal assembly having a plurality of inserts in accordance with the disclosure. 
         FIGS. 7A-7D  are various schematic views of one of the inserts of  FIG. 6A . 
         FIGS. 7E-7F  are various schematic views of a portion of a seal assembly having a plurality of the inserts of  FIG. 7A . 
         FIGS. 8A-8C  are schematic views of an alternate insert. 
         FIGS. 9A-9C  are schematic views of another alternate insert. 
         FIGS. 10A-10C  are various schematic views of a portion of a seal assembly having a plurality of the inserts of  FIG. 9A . 
     
    
    
     DETAILED DESCRIPTION 
     The description that follows includes exemplary apparatuses, methods, techniques, and 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. 
     The disclosure relates to techniques for sealing a wellbore. The techniques involve inserts used, for example, in a ram block of a blowout preventer. The inserts may be positioned about a tubular (or pipe) for forming a seal therewith. It may be desirable to provide techniques that more effectively seal, even under high pressure conditions. It may be further desirable to provide techniques that more effectively seal about a variety of pipe diameters. Preferably, such techniques involve one or more of the following, among others: ease of operation, simple design, adaptability to a variety of applications, reduced failures, performance under harsh conditions, conformance to equipment shapes and/or sizes, increased capacity, etc. The present disclosure is directed to fulfilling these needs in the art. 
       FIG. 1  depicts an offshore wellsite  100  having a blowout preventer (BOP)  108  configured to seal a wellbore  105  extending into a seabed  107 . The BOP  108  has a seal assembly  102  positioned therein. As shown, the BOP  108  is part of a subsea system  106  positioned on the seabed  107 . The subsea system  106  may also comprise a pipe (or tubular)  104  extending through the wellbore  105 , a wellhead  110  about the wellbore  105 , a conduit  112  extending from the wellbore  105 , and other subsea devices, such as a stripper and a conveyance delivery system (not shown). While the wellsite  100  is depicted as a subsea operation, it will be appreciated that the wellsite  100  may be land or water based. 
     A surface system  120  may be used to facilitate operations at the offshore wellsite  100 . The surface system  120  may comprise a rig  122 , a platform  124  (or vessel) and a surface controller  126 . Further, there may be one or more subsea controllers  128 . While the surface controller  126  is shown as part of the surface system  120  at a surface location and the subsea controller  128  is shown part of the subsea system  106  in a subsea location, it will be appreciated that one or more controllers may be located at various locations to control the surface and/or subsea systems. 
     To operate the BOP  108  and/or other devices associated with the wellsite  100 , the surface controller  126  and/or the subsea controller  128  may be placed in communication. The surface controller  126 , the subsea controller  128 , and/or any devices at the wellsite  100  may communicate via one or more communication links  134 . The communication links  134  may be any suitable communication means, such as hydraulic lines, pneumatic lines, wiring, fiber optics, telemetry, acoustics, wireless communication, any combination thereof, and the like. The BOP  108  and/or other devices at the wellsite  100  may be automatically, manually and/or selectively operated via the controllers  126  and/or  128 . 
       FIG. 2  shows a detailed, schematic view of a BOP  108  that may be used as the BOP  108  of  FIG. 1 . The BOP  108  may be a conventional BOP having a body  236  with a central passageway  238  therethrough for receiving a pipe (e.g.,  104  of  FIG. 1 ). The BOP  108  also includes a pair of conventional ram assemblies  240 ,  242  on opposite sides thereof. Examples of BOPs, ram assemblies and/or ram blocks usable with the BOP  108  are described in U.S. Pat. No. 5,735,502, the entire contents of which is hereby incorporated by reference. The ram assembly  240  has been pivotally retracted to reveal ram block  247 . The seal assembly  102  is positionable within each of the ram blocks  247  for providing a seal with a pipe positioned in the central passageway  238 . 
     Each ram assembly  240 ,  242  is in communication with a respective one of the radially opposing chambers  244  in the BOP body that extend radially outward from the central passageway  238 . Each ram assembly  240 ,  242  may include a ram body  246 , the ram block  247  and a ram door  248 . Ram door  248  may be secured to the BOP body  236  by conventional bolts (not shown) which pass through respective apertures  250  in the ram door  248  and thread to corresponding ports  251  in the BOP body  236 . 
     The ram assemblies  240 ,  242  may be pivotally mounted on the BOP body  236  by pivot arms  252 , thereby facilitating repair and maintenance of the ram blocks  247 . Bolts in the passageway  250  may thus be unthreaded from the BOP body  236 , and the ram assembly  240  swung open, as shown in  FIG. 2 , to expose the ram block  247 . 
     The ram blocks  247  have an arcuate shaped body with an arcuate shaped inlet  259  configured to receive a portion of the pipe  104  for sealing engagement therewith. Once in position, the ram block  247  may be selectively activated to move within the seal assembly  102  to a sealed position about the pipe  104  positioned therein. 
       FIGS. 3A-3B  show a portion of conventional ram blocks assemblies  12 ,  14  in various positions about the pipe  104 . The ram block assemblies  12 ,  14  may be used as part of the ram blocks  247  of  FIG. 2 . The ram blocks  247  are provided with a seal assembly  102  thereon for supporting a rubber gland (or seal)  249 . The seal assembly  102  may be configured to seal on multiple pipe diameters. During activation of the ram blocks  247 , the rubber gland  249  is advanced toward the drill pipe  104  and forced under hydraulic pressure to conform to the drill pipe  104 . To protect the rubber gland  249  (and potentially extend its life), the rubber gland  249  may be molded with inserts (or metal reinforcements)  20  that aid in retaining the gland  249  and/or prevent rubber extrusion. 
     As shown in  FIG. 3B , the inserts  20  are positionable in an elliptical, iris configuration, sometimes referred to as an insert array. The movement of the inserts  20  is similar to the iris of an eye that alters the inner diameter of the pupil (or hole) receiving the pipe  104 . The inserts  20  are slidingly moveable between a refracted (or unsealed) and a sealed position, and interlocked for cooperative movement therebetween. The inserts  20  are designed to support the rubber gland  249  to enhance a seal formed by the rubber gland  249  about the pipe  104  during operation. 
     Conventional inserts  20  are detailed in  FIGS. 4A-4C . These inserts  20  are described in further detail in U.S. Pat. No. 6,857,634, the entire contents of which is hereby incorporated by reference. The inserts  20  have an upper body  24  and a lower body  26 . Each of the upper and lower bodies  24 ,  26  are provided with a ledge  30  and a corresponding recess  36  and an anti-extrusion ledge  46  thereon. 
     To enhance the operation of the seal assembly  102 , the inserts  20  may optionally be provided with geometries that provide support to the seal assembly  102  and/or reduce extrusion of the rubber gland  249  about the pipe  104  during operation of the ram blocks  247 .  FIG. 5A  shows a portion of the array of inserts  20  of  FIG. 3B . As shown in  FIG. 5A , conventional inserts  20  define an inner diameter  560  for receiving pipe  104  ( FIG. 1 ). The inserts  20  have tips  564  at an end adjacent the inner diameter  560 , and may define gaps  562  between the inserts  20  along the inner diameter  560 . These large gaps provide space between the inserts and the drill pipe that define an extrusion path or gap for the rubber gland  249 . In some cases, extrusion gaps of up to 0.125 inches (0.32 cm) may be present. 
     To reduce or restrict the extrusion between the inserts, it may be desirable to reduce the gaps  562 . These reduced gaps may reduce the open area (or space) between the pipe  104  and the inserts  20  to restrict extrusion therethrough. As shown in  FIG. 5B , alternate inserts  20   a  are provided with extended tips  564   a  that extend beyond a secondary tip  565   a  on a seal end of the insert  20   a . The extended tips  564   a  may be used to provide a reduced gap  562   a  therebetween along inner diameter  560   a . The geometry of the inserts  20   a  may be used to minimize the extrusion gap  562   a  by providing geometry that incrementally matches various pipe sizes. The shape, size and quantity of the geometries may vary based on a desired range of coverage and/or operating conditions. 
     The inserts may be provided with various features, such as scallops (or facets) as will be described further herein, to reduce this gap to, for example, about 0.015-0.030 inches (0.38-0.76 mm) or less. In addition the inserts may also have overlapping features, such as tips, ledges or shoulders as will be described further herein, to allow greater surface area to distribute the features. Such overlapping features may be used on portions of the insert for supporting an adjacent insert from internal rubber pressures, preventing extrusion between inserts, and/or adding stiffness to the seal assembly. 
       FIGS. 6A-6D  show various views of an insert  20   a  usable in the seal assembly  102  of  FIGS. 1-3B .  FIG. 6A  shows an elliptical array of the inserts  20   a  forming a portion of an alternate seal assembly  102   a  and defining a variable inner diameter  560   a .  FIG. 6B  shows a portion of the array of inserts  20   a  of  FIG. 6A  taken along line  6 B- 6 B.  FIG. 6C  is a detailed view of a portion  6 C of the assembly  102   a  of  FIG. 6A .  FIG. 6D  is a detailed view of two of the inserts  20   a  interlocked together for slidable movement therebetween. 
     As shown in  FIGS. 6C-6D , the inserts  20   a  may be provided with extended (or pointed) tips  564   a  that terminate at a point to fill the gap  562   a  (see, e.g.,  FIG. 5B ). The extended tip  564   a  may, for example, have a radius R of about 0.03-0.05 inches (0.76-1.27 mm) near an end thereof. A tip receptacle  667   a  may be provided in the insert  20   a  for receiving the extended tip  564   a  of an adjacent insert  20   a , and for providing overlap between the inserts  20   a , as will be described further herein. 
     The elliptical array of inserts defines an inner contact surface for engaging the pipe. The inserts  20   a  may also be provided with scallops (or contact surfaces)  566   a  for engaging the pipe  104  and further filling the gaps  562   a  about inner diameter  560   a . One or more scallops  566   a  may be provided along the extended tip to define the contact surface for receiving the pipe  104 . Multiple scallops may be provided to a curved contact surface that may conform to the shape of a variety of pipe diameters. The inserts may contract and expand about the pipe to conform to the size and shape of the pipe, and the shape of the scallops can conform to the various pipes. 
       FIGS. 7A-7D  show the inserts  20   a  in greater detail. The inserts  20   a  cooperate with each other to radially expand and contract in an iris pattern (see, e.g.,  FIG. 3B ,  6 B). Each insert  20   a  has an upper body  768   a  and a lower body  770   a  with a rib  772   a  therebetween integrally made of metal. The upper body  768   a  has the same shape as the lower body  770   a  and is a mirror image thereof. The rib  772   a  is substantially smaller than the upper body  768   a  and lower body  770   a  to allow the rubber gland  249  to flow between the metal inserts  20   a  as the ram blocks  247  are pressed together as shown in  FIG. 3B . 
     The upper body  768   a  and the lower body  770   a  each have a leading face  774   a  a shown in  FIG. 7A  and a trailing face  776   a  as shown in  FIG. 7B . The leading face  774   a  and the trailing face  776   a  meet at the extended tip  564   a  on one end beyond secondary tip  565   a , and are joined by a heel (or radially outwardly opposing face)  778   a  at an opposite end thereof. The upper body  768   a  and the lower body  770   a  each also have an inverted ledge  782   a  extending from the leading face  774   a , and an inverted recess  784   a  indented into the trailing face  776   a  as shown in  FIG. 7C . The inverted recess  784   a  is configured to receive the inverted ledge  782   a  of an adjacent insert as depicted in  FIG. 6D  for slidable support therebetween. The inverted recess  784   a  and the inverted ledge  782   a  may be mated to cooperatively interact similar to the ledge  30  and recess  36  of  FIG. 4A . The ledges  782   a  and recesses  784   a  may be inverted from the configuration of ledge  30  and recess  36  positioned on an outer surface of the insert  20  of  FIG. 4A . In the inverted configuration, the ledges  782   a  and recesses  784   a  are positioned on an inner surface of the upper and lower bodies  768   a ,  770   a  to further support the inserts  20   a  as pressure is applied thereto during a sealing operation. 
     The leading face  774   a  has a plurality of scallops (or contact surfaces or facets)  566   a  on a portion thereof as shown in  FIG. 7A . One or more scallops  566   a  may be provided. As shown, four scallops  566   a  extend into the leading face  774   a . The scallops  566   a  may be concave indentations configured to receivingly engage the pipe  104 . To further reduce the gap  562   a  ( FIG. 5B ), the scallops  566   a  of adjacent inserts  20   a  are preferably shaped to conform to the shape of the inner diameter  560   a  ( FIG. 4B ). The scallops  566   a  may also be shaped such that, as the inner diameter  560   a  defined by the inserts adjusts to a given pipe size, the scallops  566   a  conform to the pipe shape. Additional scallops  566   a  may be added to provide conformity to more pipe sizes. In some cases, the scallops  566   a  may define an edge  787   a  therebetween. The edges  787   a  may optionally be flattened or curved to provide a smoother transition between the scallops  566   a.    
       FIG. 7D  shows a portion of the insert  20   a  depicting the extended tip  564   a  in greater detail.  FIGS. 7E and 7F  show views of a portion of an array of the inserts  20   a . The insert  20   a  has a tip receptacle  667   a  extending into the upper body  768   a  for receiving the extended tip  564   a  of an adjacent insert  20   a . This overlapped configuration may be used to more tightly fit the inserts  20   a  together, and further conform the extended tip  564   a  to the shape of the pipe. Additionally, this overlapping configuration may be used to further prevent extrusion between inserts. 
       FIGS. 8A-8B  show an alternate insert  20   b  that is similar to the insert  20   a , except that the upper body  768   b  and lower body  770   b  each have a recess  888   b  extending into leading face  774   b  with corresponding ledges  890   b  extending into trailing face  776   b . The upper body  768   b  and the lower body  770   b  have a rib  772   b  therebetween. In this configuration, the recess  888   b  and ledges  890   b  are upright (not inverted as shown in the insert  20   a  of  FIGS. 7A-7F ), and are positioned on an outer surface of the insert  20   b . The recess  888   b  and ledge  890   b  may cooperatively interact similarly to the ledge  30  and recess  36  of  FIG. 4A . One or more recesses  888   b  and corresponding ledges  890   b  may be provided about various portions of the upper and/or lower body  786   b ,  770   b  of each insert  20   b.    
     As shown in  FIGS. 8A and 8B , a shoulder (or radially inwardly directed anti-extrusion ledge)  892   b  extends from the leading face  774   b  and a corresponding ridge  894   b  extends into a trailing face  776   b  in the upper body  786   b  on each insert  20   a . The shoulder  892   b  and ridge  894   b  may operate similar to the radially inwardly directed anti-extrusion ledge  46  of the insert  20  of  FIG. 4A . 
     The shoulder  892   b  and ridge  894   b  define a first tier for interaction between the inserts  20   b . The ledge  890   b  extends from the trailing face  776   b  to define a second tier for interaction with recess  888   b . This two tier configuration may be used to support the cooperative movement and support of the inserts  20   b , and prevent extrusion therebetween. One or more shoulders  892   b  and corresponding ridges  894   b  may also be provided about various portions of the insert  20   b  to provide support and/or prevent extrusion between adjacent inserts. Scallops  566   b  adjacent extended tip  564   b , similar to the scallops  566   a  of  FIGS. 7A-7C , may also be provided to reduce the gaps between the inserts  20   b  and further prevent extrusion therebetween. Extended tip  564   b  is provided with a secondary tip  565   b  therebelow. 
       FIGS. 9A-9B  show an alternate insert  20   c  that is similar to the insert  20   b , except that the upper body  768   c  and lower body  770   c  each have multiple recesses  888   c  extending into leading face  774   c  with corresponding upright ledges  890   c  extending into trailing face  776   c . The upper body  768   c  and the lower body  770   c  have a rib  772   c  therebetween. The multiple recesses  888   c  and multiple ledges  890   c  may cooperatively interact similarly to the ledges  890   b  and recesses  888   b  of  FIGS. 8A-8B . In this case, multiple recesses  888   c  and corresponding ledges  890   c  are provided at various depths to provide for additional contact between adjacent inserts. Additional ledges  890   c  and recesses  888   c  may be used to increase the amount of overlap between inserts and/or to reduce extrusion therebetween. One or more recesses  888   c  and corresponding ledges  890   c  for receiving that shoulder may also be provided about various portions of the upper and/or lower body of each insert  20   c.    
     As shown in  FIGS. 9A and 9B , the insert  20   c  may also be provided with a shoulder (or radially inwardly directed antiextrusion ledge)  892   c  extending from the leading face  774   c  and a corresponding ridge  894   c  extending into the trailing face  776   c  in the upper body  786   c  on each insert  20   c . The shoulder  892   c  and ridge  894   c  may operate similar to the shoulder  892   b  and ridge  894   b  of  FIGS. 8A and 8B . 
     The recesses  888   c  and shoulders  890   c  define a first and second tier for interaction between the inserts  20   c . The shoulder  892   c  extends from the leading face  774   c  to define a third tier for interaction between the inserts  20   c . This three tier configuration may be used to support the cooperative movement and support of the inserts  20   c , and prevent extrusion therebetween. One or more shoulders  892   c  and corresponding ridges  894   c  may also be provided about various portions of the insert  20   c  to provide support and/or prevent extrusion between adjacent inserts. Scallops  566   c  positioned about extended tip  564   c , similar to the scallops  566   a  of  FIGS. 7A-7C , may also be provided to reduce the gaps between the inserts  20   c  and further prevent extrusion therebetween. Two extended tips  564   c  are provided with a secondary tip  565   c  therebelow. 
       FIGS. 10A-10C  show views of a portion of an array of the inserts  20   c . Each insert  20   c  has a tip receptacle  667   c  extending into the upper body  768   c  and lower body  770   c  for receiving the extended tip  564   c  of an adjacent insert  20   c  as shown in  FIGS. 10A and 10B . This overlapped configuration may be used to more tightly fit the inserts  20   c  together, and further conform the extended tips  564   c  to the shape of the pipe.  FIG. 10C  also shows the ledges  890   c  and shoulder  892   c  of a first insert  20   c  being received by the recesses  888   c  and ridge  894   c , respectively of an adjacent insert  20   c  for further overlap therebetween. These overlapping configurations may also be used to further prevent extrusion between inserts. 
     In an example operation, the ram blocks  247  may actuated between the retracted position of  FIG. 4A  and to the sealed position of  FIG. 4B . The inserts  20   a - c  of the seal assembly  102   a - c  may slidingly move to cooperatively conform to the shape of the pipe  104  for sealing engagement therewith. The inserts  20   a - c  may be provided with various combinations of features, such as recesses, shoulders, ridges, scallops, receptacles, and extended tips to enhance operation of the seal assembly. 
     It will be appreciated by those skilled in the art that the techniques disclosed herein can be implemented for automated/autonomous applications via software configured with algorithms to perform the desired functions. These aspects can be implemented by programming one or more suitable general-purpose computers having appropriate hardware. The programming may be accomplished through the use of one or more program storage devices readable by the processor(s) and encoding one or more programs of instructions executable by the computer for performing the operations described herein. The program storage device may take the form of, e.g., one or more floppy disks; a CD ROM or other optical disk; a read-only memory chip (ROM); and other forms of the kind well known in the art or subsequently developed. The program of instructions may be “object code,” i.e., in binary form that is executable more-or-less directly by the computer; in “source code” that requires compilation or interpretation before execution; or in some intermediate form such as partially compiled code. The precise forms of the program storage device and of the encoding of instructions are immaterial here. Aspects of the disclosure may also be configured to perform the described functions (via appropriate hardware/software) solely on site and/or remotely controlled via an extended communication (e.g., wireless, internet, satellite, etc.) network. 
     While the present disclosure describes specific aspects of the disclosure, numerous modifications and variations will become apparent to those skilled in the art after studying the disclosure, including use of equivalent functional and/or structural substitutes for elements described herein. For example, aspects of the disclosure can also be implemented using various combinations of one or more recesses, shoulders, ridges, scallops, receptacles, extended tips and/or other features about various portions of the inserts. All such similar variations apparent to those skilled in the art are deemed to be within the scope of the disclosure as defined by the appended claims. 
     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 subject matter herein.