Patent Publication Number: US-9885222-B2

Title: Stage tool apparatus and components for same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of the filing date of, and priority to, U.S. Application No. 61/764,629, filed Feb. 14, 2013, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     This disclosure relates in general to oil and gas exploration and production operations, and in particular to supporting a casing that extends within a wellbore, and isolating one or more formations through which the wellbore extends, to facilitate oil and gas exploration and production operations, including drill-out operations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a stage tool apparatus according to an exemplary embodiment, the stage tool apparatus including a box sub, a body assembly and a pin sub. 
         FIG. 2  is a partially exploded view of the stage tool apparatus of  FIG. 1  according to an exemplary embodiment. 
         FIG. 3  is a sectional view of the stage tool apparatus of  FIG. 1  according to an exemplary embodiment. 
         FIG. 4  is a perspective view of the body assembly of  FIG. 1  according to an exemplary embodiment, the body assembly including an outer sleeve and a plurality of components engaged therewith or disposed therein. 
         FIG. 5  is a perspective view of a section of the body assembly of  FIG. 4  according to an exemplary embodiment, and depicts the outer sleeve and at least a portion of the plurality of components engaged therewith or disposed therein. 
         FIG. 6  is a perspective view of the plurality of components of  FIGS. 4 and 5  according to an exemplary embodiment. 
         FIG. 7  is a perspective view of a section of a portion of the plurality of components of  FIGS. 4-6  according to an exemplary embodiment. 
         FIG. 8  is an exploded view of a portion of the plurality of components of  FIGS. 4-7  according to an exemplary embodiment. 
         FIG. 9  is a sectional view of the body assembly of  FIGS. 4 and 5  according to an exemplary embodiment. 
         FIG. 10  is a perspective view of a shear screw according to an exemplary embodiment, the shear screw being one of the components shown in  FIG. 6 . 
         FIG. 11  is an enlarged view of a portion of  FIG. 8  and illustrates a lock key and a spring according to respective exemplary embodiments. 
         FIG. 12  is a perspective view of the lock key and the spring of  FIG. 11 . 
         FIG. 13  is an enlarged view of a portion of  FIG. 3 . 
         FIG. 14  is a partial sectional view of the shear screw of  FIG. 10  extending through the outer sleeve of the body assembly of  FIG. 4 , according to an exemplary embodiment. 
         FIG. 15  is a partial sectional view of the stage tool apparatus of  FIG. 1  extending within a wellbore and placed in an operational mode, according to an exemplary embodiment. 
         FIG. 16  is a partial sectional view of the stage tool apparatus of  FIG. 1  extending within a wellbore and placed in an operational mode similar to that of  FIG. 15 , but also including a dart seated within the apparatus, according to an exemplary embodiment. 
         FIG. 16 a    is a partial sectional view of a shear screw when the stage tool apparatus of  FIG. 1  is in the operational mode of  FIG. 16 , according to an exemplary embodiment. 
         FIG. 17  is a partial sectional view of the stage tool apparatus of  FIG. 1  extending within a wellbore and placed in an operational mode, according to an exemplary embodiment. 
         FIG. 18  is a partial sectional view of the stage tool apparatus of  FIG. 1  extending within a wellbore and placed in an operational mode similar to that of  FIG. 17 , but also including a plug seated within the apparatus, according to an exemplary embodiment. 
         FIG. 18 a    is a view similar to that of  FIG. 13 , but depicting the portion shown in  FIG. 13  when the stage tool apparatus of  FIG. 1  is in the operational mode of  FIG. 18 , according to an exemplary embodiment. 
         FIG. 19  is a partial sectional view of the stage tool apparatus of  FIG. 1  extending within a wellbore and placed in an operational mode, according to an exemplary embodiment. 
         FIG. 19 a    is a view similar to that of  FIG. 18 a   , but depicting the portion shown in  FIG. 18 a    when the stage tool apparatus of  FIG. 1  is in the operational mode of  FIG. 19 , according to an exemplary embodiment. 
         FIG. 20  is a perspective view of a section of a portion of a stage tool apparatus, according to an exemplary embodiment, the stage tool including a dart, a lower seat, a plug, and an upper seat. 
         FIG. 21  is a perspective view of the dart of  FIG. 20  according to an exemplary embodiment. 
         FIG. 21A  is a side view of the dart of  FIG. 20  according to an exemplary embodiment. 
         FIG. 21B  is a sectional view of the dart of  FIG. 20 , taken along line  21 B- 21 B of  FIG. 21A , according to an exemplary embodiment. 
         FIG. 21C  is a bottom plan view of the dart of  FIG. 20  according to an exemplary embodiment. 
         FIG. 21D  is another sectional view of the dart of  FIG. 20 , taken along line  21 D- 21 D of  FIG. 21C  but inverted, according to an exemplary embodiment. 
         FIG. 22  is a perspective view of the lower seat of  FIG. 20  according to an exemplary embodiment. 
         FIG. 22A  is a top plan view of the lower seat of  FIG. 20  according to an exemplary embodiment. 
         FIG. 23  is a perspective view of the plug of  FIG. 20  according to an exemplary embodiment. 
         FIG. 23A  is a side view of the plug of  FIG. 20  according to an exemplary embodiment. 
         FIG. 23B  is a sectional view of the plug of  FIG. 20 , taken along line  23 B- 23 B of  FIG. 23A , according to an exemplary embodiment. 
         FIG. 23C  is a bottom plan view of the plug of  FIG. 20  according to an exemplary embodiment. 
         FIG. 23D  is another sectional view of the plug of  FIG. 20 , taken along line  23 D- 23 D of  FIG. 23C  but inverted, according to an exemplary embodiment. 
         FIG. 24  is a perspective view of the upper seat of  FIG. 20  according to an exemplary embodiment. 
         FIG. 24A  is a top plan view of the upper seat of  FIG. 20  according to an exemplary embodiment. 
         FIG. 25  is a partial sectional view of the stage tool apparatus of  FIG. 20  extending within a wellbore and placed in an operational mode, according to an exemplary embodiment. 
         FIG. 26  is a partial sectional view of the stage tool apparatus of  FIG. 20  extending within a wellbore and placed in an operational mode similar to that of  FIG. 25 , but also including the dart seated in the lower seat, according to an exemplary embodiment. 
         FIG. 26A  is a sectional view, taken along line  26 A- 26 A of  FIG. 26 , of the dart seated in the lower seat when the stage tool apparatus of  FIG. 20  is in the operational mode of  FIG. 26 , according to an exemplary embodiment. 
         FIG. 26B  is an enlarged view of a portion of  FIG. 26 . 
         FIG. 27  is a partial sectional view of the stage tool apparatus of  FIG. 20  extending within a wellbore and placed in an operational mode, according to an exemplary embodiment. 
         FIG. 28  is a partial sectional view of the stage tool apparatus of  FIG. 20  extending within a wellbore and placed in an operational mode similar to that of  FIG. 27 , but also including the plug seated within the upper seat, according to an exemplary embodiment. 
         FIG. 28A  is a partial sectional view of the plug seated in the upper seat when the stage tool apparatus of  FIG. 20  is in the operational mode of  FIG. 28 , according to an exemplary embodiment. 
         FIG. 29  is a partial sectional view of the stage tool apparatus of  FIG. 20  extending within a wellbore and placed in an operational mode, according to an exemplary embodiment. 
         FIG. 30  is a view similar to that of  FIG. 26  but depicting the apparatus of  FIG. 20  placed in another operational mode, according to an exemplary embodiment. 
         FIG. 30A  is a partial sectional view of the dart seated in the lower seat when the stage tool apparatus of  FIG. 20  is in the operational mode of  FIG. 30 , according to an exemplary embodiment. 
         FIG. 30B  is another partial sectional view of the dart seated in the lower seat when the stage tool apparatus of  FIG. 20  is in the operational mode of  FIG. 30 , according to an exemplary embodiment. 
         FIG. 31  is a view similar to that of  FIG. 28A  but depicting the apparatus of  FIG. 20  placed in another operational mode, according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The foregoing disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” “uphole,” “downhole,” “upstream,” “downstream,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the tool, or the apparatus, in use or operation in addition to the orientation depicted in the figures. For example, if the apparatus in the figures is turned over, elements described as being “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
     In an exemplary embodiment, as illustrated in  FIGS. 1-3 , a downhole tool, and in particular a stage tool apparatus, is generally referred to by the reference numeral  10  and includes a box sub  12 , a body assembly  14 , and a pin sub  16 . The box sub  12  includes an internal threaded connection  12   a  at one of its end portions, and an external threaded connection  12   b  that is axially spaced between the internal threaded connection  12   a  and the other of its end portions. The box sub  12  defines an internal passage  12   c.    
     Even though  FIG. 3  depicts the stage tool apparatus  10  in a vertical orientation associated with vertical wellbores, it should be understood by those skilled in the art that the apparatus according to the present disclosure is equally well suited for use in wellbores having other orientations including slanted wellbores, horizontal wellbores, multilateral wellbores or the like. Accordingly, it should be understood by those skilled in the art that the use of directional terms such as “above,” “top,” “below,” “upper,” “lower,” “upward,” “bottom,” “downward,” “uphole,” “downhole” and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure, the uphole direction or top being toward the surface of the well, the downhole direction or bottom being toward the toe of the well. 
     The body assembly  14  includes an outer tubular member, such as an outer sleeve  18 , and a plurality of components  20  engaged therewith or disposed therein, which components will be described in greater detail below. The outer sleeve  18  includes an internal threaded connection  18   a  at one of its end portions and an internal threaded connection  18   b  at the other of its end portions. The internal threaded connection  18   a  is coupled to the external threaded connection  12   b  of the box sub  12 , thereby coupling the box sub  12  to the body assembly  14 . The outer sleeve  18  defines an internal passage  18   c . A sealing element, such as an o-ring  22 , extends in an annular channel  12   d  formed in the outside surface of the box sub  12 , the o-ring  22  sealingly engaging the inside surface of the outer sleeve  18 . 
     The pin sub  16  includes an external threaded connection  16   a  at one end portion, which is coupled to the internal threaded connection  18   b  of the outer sleeve  18  of the body assembly  14 , thereby coupling the pin sub  16  to the body assembly  14 . The pin sub  16  further includes an external threaded connection  16   b  at the other end portion that is distal to the body assembly  14 . The pin sub  16  defines an internal passage  16   c . As shown in  FIG. 3 , a sealing element, such as an o-ring  24 , extends in an annular channel  16   d  formed in the outside surface of the pin sub  16 . 
     In an exemplary embodiment, as illustrated in  FIGS. 4-9  with continuing reference to  FIGS. 1-3 , the outer sleeve  18  further includes a plurality of circumferentially-spaced flow ports  18   d , each of which extends radially through the outer sleeve  18 , and a plurality of circumferentially-spaced ports  18   e  spaced axially from the plurality of ports  18   d , with each of the ports  18   e  also extending radially through the outer sleeve  18 . 
     As noted above, the body assembly  14  includes a plurality of components  20  engaged with the outer sleeve  18  or disposed therein. The plurality of components  20  includes an upper tubular member such as an upper sleeve  26 , a lower tubular member such as a lower sleeve  28 , an upper seat  30 , a lower seat  32 , a plurality of components such as fasteners  34 , a plurality of components such as fasteners  36 , a plurality of shear screws  38 , a plurality of shear screws  40 , a plurality of springs  42 , a plurality of lock keys  44 , and sealing elements such as o-rings  46 ,  48 ,  50  and  52 . 
     The upper sleeve  26  includes a plurality of axially-extending channels  26   a  formed in its outside surface, a circumferentially-extending shoulder  26   b  formed in its inside surface, and diametrically opposite arcuate notches  26   c  and  26   d  formed in one of its end portions. Each of the channels  26   a  includes an axially-extending channel or recess  26   aa  formed in a surface of the upper sleeve  26  defined by the channel  26   a . The upper sleeve  26  defines an internal passage  26   e.    
     The lower sleeve  28  includes a plurality of axially-extending channels  28   a  formed in its outside surface, a circumferentially-extending shoulder  28   b  formed in its inside surface, an arcuate notch  28   c  formed in a first end portion of the lower sleeve  28 , and an arcuate notch (not shown) formed in the first end portion of the lower sleeve  28  and diametrically opposite the arcuate notch  28   c . The lower sleeve  28  defines an internal passage  28   e.    
     In an exemplary embodiment, as illustrated in  FIG. 10  with continuing reference to  FIGS. 1-9 , each of the shear screws  38  includes a cylindrical body  38   a , an external threaded connection  38   b  at one end portion of the cylindrical body  38   a , a shoulder  38   c  formed in the cylindrical body  38   a  and adjacent the external threaded connection  38   b , a generally cylindrical shear portion  38   d  extending from the other end portion of the cylindrical body  38   a , and a shoulder  38   e  adjacent the proximal end of the generally cylindrical shear portion  38   d , the shoulder  38   e  defining a flat  38   f . One or more shear planes  38   g  extend through the generally cylindrical shear portion  38   d , and are offset from, and generally parallel to, the flat  38   f . Each of the one or more shear planes  38   g  is adapted to define the location at which at least a portion of the generally cylindrical shear portion  38   d  shears off from the remainder of the shear screw  38 , under conditions to be described below. 
     The shear screws  40  are identical to the shear screws  38 . Each of the shear screws  40  includes features that are identical to the features of each of the shear screws  38 . Reference numerals used to refer to the features of the shear screws  40  that are identical to the features of the shear screws  38  will correspond to the reference numerals used to refer to the features of the shear screws  38  except that the prefix for the reference numerals used to refer to the features of the shear screws  38 , that is,  38 , will be replaced by the prefix of the shear screws  40 , that is,  40 . 
     In an exemplary embodiment, as illustrated in  FIGS. 11 and 12  with continuing reference to  FIGS. 1-10 , each of the springs  42  includes opposing curved end portions  42   a  and  42   b  that define generally flat surfaces  42   aa  and  42   ba , respectively, and a middle portion  42   c . An arcuate portion  42   d  extends between the curved end portion  42   a  and the middle portion  42   c . An arcuate portion  42   e  extends between the curved end portion  42   b  and the middle portion  42   c.    
     Each of the lock keys  44  includes a bar member  44   a  defining sides  44   aa  and  44   ab  spaced in a parallel relation, and having opposing curved end portions  44   ac  and  44   ad . Protrusions  44   b  and  44   c  extend from the side  44   ab  and include curved outer surfaces  44   ba  and  44   ca , respectively, which are flush with the extents of the curved end portions  44   ac  and  44   ad , respectively. The protrusions  44   b  and  44   c  further include facing curved inner surfaces  44   bb  and  44   cb , respectively. An axially-extending region  44   d  is defined by the side  44   ab  and the curved inner surfaces  44   bb  and  44   cb.    
     In an exemplary embodiment with continuing reference to  FIGS. 1-12 , when the stage tool apparatus  10  is in an assembled condition as illustrated in  FIGS. 1 and 3 , the external threaded connection  12   b  of the box sub  12  is threadably engaged with the internal threaded connection  18   a  of the outer sleeve  18 , thereby coupling the box sub  12  to the outer sleeve  18 . The o-ring  22  extends in the annular channel  12   d  formed in the outside surface of the box sub  12 , and sealingly engages the inside surface of the outer sleeve  18 . The external threaded connection  16   a  of the pin sub  16  is threadably engaged with the internal threaded connection  18   b  of the outer sleeve  18 , thereby coupling the pin sub  16  to the outer sleeve  18 . The o-ring  24  extends in the annular channel  16   d  formed in the outside surface of the pin sub  16 , and sealingly engages an inside surface of the outer sleeve  18 . 
     An annular region  54  ( FIG. 3 ) is defined between the inside surface of the outer sleeve  18  and an outside surface of the end portion of the pin sub  16  that extends within the internal passage  18   c  of the outer sleeve  18 . The annular region  54  is in fluid communication with the outside of the outer sleeve  18  and thus the apparatus  10  via the ports  18   e . At least the lower end portion of the lower sleeve  28  extends within the annular region  54 . A plurality of fasteners  56  extend through the outer sleeve  18  and into an annular channel formed in the outside surface of the box sub  12 , thereby locking the box sub  12  to the outer sleeve  18 . A plurality of fasteners  58  extend through the outer sleeve  18  and into an annular channel formed in the outside surface of the pin sub  16 , thereby locking the pin sub  16  to the outer sleeve  18 . 
     The upper sleeve  26  extends within the internal passage  18   c  of the outer sleeve  18 . The lower sleeve  28  also extends within the internal passage  18   c  of the outer sleeve  18 . Within the internal passage  18   c , the upper sleeve  26  is engaged with the lower sleeve  28  so that lower end portions of the upper sleeve  26  defined by the arcuate notches  26   c  and  26   d  are interposed between upper end portions of the lower sleeve  28  defined in part by the arcuate notch  28   c , as shown in  FIGS. 6 and 7 . In an exemplary embodiment, axial gaps are defined between axially-facing end surfaces defined by the interposed lower end portions of the upper sleeve  26  and corresponding axially-facing end surfaces defined by the interposed upper end portions of the lower sleeve  28 ; in an exemplary embodiment, grease is disposed in the axial gaps to eliminate any metal-to-metal surface seal. 
     The upper seat  30  is disposed within the upper sleeve  26 , engaging the shoulder  26   b  of the upper sleeve  26 . The o-ring  46  sealingly engages the inside surface of the outer sleeve  18 , and the o-ring  48 , which is axially spaced from the o-ring  46 , also sealingly engages the inside surface of the outer sleeve  18 . As a result, the channels  26   a  and thus the recesses  26   aa  are fluidically isolated from the internal passages  12   c ,  16   c ,  18   c ,  26   e  and  28   e . The shear screws  38  extend through the outer sleeve  18  and into an opening, such as an annular channel  26   f , formed in the outside surface of the upper sleeve  26 , thereby generally preventing relative axial movement between the upper sleeve  26  and the outer sleeve  18 . 
     The lower seat  32  is disposed within the lower sleeve  28 , engaging the shoulder  28   b  of the lower sleeve  28 . Each of the fasteners  36  is coupled to the outer sleeve  18  and extends radially from the outer sleeve  18  and into a respective one of the channels  28   a  of the lower sleeve  28 , thereby preventing or at least resisting relative rotation between the lower sleeve  28  and the outer sleeve  18 . As shown in  FIG. 5 , the lower sleeve  28  blocks the ports  18   d , the o-ring  50  sealingly engages the inside surface of the outer sleeve  18 , and the o-ring  52 , which is axially spaced from the o-ring  50 , sealingly engages the inside surface of the outer sleeve  18 . As a result, the ports  18   d  are fluidically isolated from the internal passages  12   c ,  16   c ,  18   c ,  26   e  and  28   e . The shear screws  40  extend through the outer sleeve  18  and into an opening, such as an annular channel  28   d , formed in the outside surface of the lower sleeve  28 , thereby generally preventing or at least resisting relative axial movement between the lower sleeve  28  and the outer sleeve  18 . 
     In an exemplary embodiment, as illustrated in  FIG. 13  with continuing reference to  FIGS. 1-12 , when the stage tool apparatus  10  is in an assembled condition as illustrated in  FIGS. 1 and 3 , each of the springs  42  is disposed in a respective one of the recesses  26   aa  of the upper sleeve  26 . Each of the lock keys  44  is disposed in a respective one of the recesses  26   aa  so that the respective spring  42  is disposed radially between the upper sleeve  26  and the lock key  44 , and is biased against the lock key  44  in an outwardly radial direction. At least one of the arcuate portions  42   d  and  42   e  of each spring  42  engages the vertically-extending surface of the sleeve  26  defined by the corresponding recess  26   aa . For each of the springs  42  and its corresponding lock key  44 , the opposing curved end portions  42   a  and  42   b  engage or nearly engage the curved inner surfaces  44   bb  and  44   cb , respectively, the surfaces  42   aa  and  42   ba  engage the side  44   ab , and the spring  42  extends within the region  44   d  of the corresponding lock key  44 . Each of the fasteners  34  is coupled to the outer sleeve  18  and extends radially from the outer sleeve  18  and into a respective one of the channels  26   a  of the upper sleeve  26 , thereby preventing or at least resisting relative rotation between the upper sleeve  26  and the outer sleeve  18 . As shown in  FIG. 13  and also in  FIG. 5 , each of the fasteners  34  engages at least the side  44   aa  of the corresponding lock key  44  at or proximate the curved end portion  44   ac , thereby energizing the corresponding spring  42 . More particularly, as a result of the engagements of the fasteners  34  with the sides  44   aa  of the respective lock keys  44 , at least one of the arcuate portions  42   d  and  42   e  of each of the springs  42  is compressed between the vertically-extending surface of the sleeve  26  defined by the corresponding recess  26   aa  and the side  44   ab  of the corresponding lock key  44 , thereby energizing the at least one of the arcuate portions  42   d  and  42   e  so that each of the springs  42  is energized and urges the corresponding lock key  44  radially outwards and out of the corresponding recess  26   aa . However, the corresponding fastener  34  that is engaged with the side  44   aa  of the corresponding lock key  44  prevents or at least resists at least a portion of the lock key  44  from being pushed radially outwardly by the corresponding spring  42 . 
     As noted above, the shear screws  38  extend through the outer sleeve  18  and into the annular channel  26   f  formed in the outside surface of the upper sleeve  26 , thereby generally preventing or at least resisting relative axial movement between the upper sleeve  26  and the outer sleeve  18 . In an exemplary embodiment, as illustrated in  FIG. 14 , each of the flats  38   f  engages a respective shoulder  18   f  of the outer sleeve  18  defined by, for example, a respective counterbore  18   g  in which the respective shear screw  38  is disposed, so that the shear screw  38  can be tightened up against the outer sleeve  18  for extra support, thereby preventing, or at least resisting, any twisting, slipping or stripping of the external threaded connection  38   b . Each of the counterbores  18   g  includes an internal threaded connection  18   h  that is threadably engaged with the external threaded connection  38   b  of the respective shear screw  38 . Likewise, as noted above, the shear screws  40  extend through the outer sleeve  18  and into the annular channel  28   d  formed in the outside surface of the lower sleeve  28 , thereby generally preventing or at least resisting relative axial movement between the lower sleeve  28  and the outer sleeve  18 . Each of the flats  40   f  engages a shoulder  18   i  (shown in  FIG. 16 a   ) of the outer sleeve  18  defined by, for example, a counterbore  18   j  (shown in  FIG. 16 a   ) in which the shear screw  40  is disposed, so that the shear screw  40  can be tightened up against the outer sleeve  18  for extra support, thereby preventing, or at least resisting, any twisting, slipping or stripping of the threaded connection  40   b . Each of the counterbores  18   j  includes an internal threaded connection  18   k  (shown in  FIG. 16 a   ) that is threadably engaged with the external threaded connection  40   b  of the respective shear screw  40 . 
     In several exemplary embodiments, the apparatus  10  or any component thereof includes, in whole or in part, one or more embodiments or portions thereof disclosed in U.S. patent application Ser. No. 12/898,444, filed Oct. 5, 2010, the entire disclosure of which is incorporated herein by reference. 
     In operation, in an exemplary embodiment, the apparatus  10  is initially in its assembled condition described above and is part of a tubular string or casing. A threaded end of a tubular support member (not shown) that defines an internal passage may be coupled to the internal threaded connection  12   a  of the box sub  12  so that the internal passage of the tubular support member is in fluid communication with the internal passage  12   c  of the box sub  12 , the internal passage  18   c  of the outer sleeve  18 , the internal passage  26   e  of the upper sleeve  26 , the internal passage  28   e  of the lower sleeve  28 , and the internal passage  16   c  of the pin sub  16 . Similarly, a threaded end of another tubular member (not shown) that defines an internal passage may be coupled to the external threaded connection  16   b  of the pin sub  16  so that the internal passage of the other tubular support member is in fluid communication with the internal passage  12   c  of the box sub  12 , the internal passage  18   c  of the outer sleeve  18 , the internal passage  26   e  of the upper sleeve  26 , the internal passage  28   e  of the lower sleeve  28 , and the internal passage  16   c  of the pin sub  16 . 
     As illustrated in  FIG. 15 , the tubular string or casing of which the apparatus  10  is a part is positioned within a preexisting structure such as, for example, a wellbore  60  that traverses one or more subterranean formations, thereby defining an annular region  62  between the inside wall of the wellbore and the outside surface of the outer sleeve  18 . As shown in  FIG. 15 , the apparatus  10  is in a neutral configuration, which generally corresponds to the assembled condition described above in which, inter alia, the lower sleeve  28  blocks the ports  18   d , which are fluidically isolated from the internal passages  12   c ,  16   c ,  18   c ,  26   e  and  28   e . As a result, the annular region  62  is fluidically isolated from the internal passages  12   c ,  16   c ,  18   c ,  26   e  and  28   e.    
     In an exemplary embodiment, during or after the positioning of the apparatus  10  within the wellbore  60 , fluidic materials  64  are injected into and circulated through the apparatus  10  via the internal passage  12   c , the internal passage  18   c , the internal passage  26   e , the internal passage  28   e , and the internal passage  16   c . In an exemplary embodiment, the fluidic materials  64  may be circulated through and out of the tubular string or casing of which the apparatus  10  is a part and into the wellbore  60 . In several exemplary embodiments, the fluidic materials  64  may include drilling fluids, drilling mud, water, other types of fluidic materials, or any combination thereof. 
     As illustrated in  FIG. 16 , a blocking element such as, for example, a dart  66 , is injected into the apparatus  10  through at least the passage  12   c  and the internal passage  26   e  defined by the upper sleeve  26  until the dart  66  is seated in the lower seat  32 . As a result, the flow of any fluidic materials, including the fluidic materials  64 , through the lower sleeve  28  and therebelow is blocked. 
     Continued injection of the fluidic materials  64  into the apparatus  10 , following the seating of the dart  66  in the lower seat  32 , pressurizes the tubular string, of which the apparatus  10  is a part, above the dart  66 . As a result, the dart  66 , the lower seat  32  and the lower sleeve  28  are urged downward, relative to at least the outer sleeve  18  and the shear screws  40 , so that a radially-extending surface  28   f  of the lower sleeve  28  that is defined by the annular channel  28   d  bears against the shear portions  40   d  of the respective shear screws  40 . Continued injection of the fluidic materials  64  into the apparatus  10 , following the surface  28   f  initially bearing against the shear portions  40   d , causes the respective shear portions  40   d  of the shear screws  40  to shear, at which point the dart  66 , the lower seat  32  and the lower sleeve  28  move downward, as viewed in  FIG. 16 , relative to the upper sleeve  26  and the outer sleeve  18  of the apparatus  10 . 
     As illustrated in  FIG. 16 a   , each of the shear portions  40   d  shears along the respective shear plane  40   g . Since the shear plane  40   g  is offset from, and generally parallel to, the flat  40   f  that is tightened against and engages the surface  18   i  of the outer sleeve  18 , or since the shear plane  40   g  extends through the shear portion  40   d  rather than through, for example, the external threaded connection  40   b , a cleaner shear along the shear plane  40   g  is achieved. 
     During the downward movement of the dart  66 , the lower seat  32  and the lower sleeve  28 , the channels  28   a  of the lower sleeve  28  move relative to the fasteners  36 . As a result of the extension of the fasteners  36  into the respective channels  28   a , the fasteners  36  guide the lower sleeve  28  as it moves downward, continuing to prevent or at least resist any relative rotation between the lower sleeve  28  and the outer sleeve  18 . During the downward movement of the dart  66 , the lower seat  32  and the lower sleeve  28 , the lower end of the lower sleeve  28  is further received by the annular region  54 . 
     As illustrated in  FIG. 17 , the dart  66 , the lower seat  32  and the lower sleeve  28  continue to move downward until the fasteners  36  engage the surfaces of the lower sleeve  28  defined by the upper ends of the respective channels  28   a . As a result of these engagements, the lower sleeve  28  and thus the dart  66  and the lower seat  32  are prevented from moving any further downward. As a result of the downward movement of the dart  66 , the lower seat  32  and the lower sleeve  28 , the apparatus  10  is in an open configuration in which the ports  18   d  are not blocked by any of the upper sleeve  26  and the lower sleeve  28  and thus the annular region  62  is in fluid communication with at least the internal passage  12   c , the internal passage  26   e  defined by the upper sleeve  26 , and the internal passage  18   c  via the ports  18   d.    
     In an exemplary embodiment, instead of placing the apparatus  10  in the open configuration mechanically via the engagement between the dart  66  and the lower seat  32  and the subsequent downward movement of the dart  66 , the lower seat  32  and the lower sleeve  28 , the apparatus  10  is placed in the open configuration hydraulically by pressurizing the tubular string of which the apparatus  10  is a part, and controlling the respective pressures within one or more of the wellbore  60 , the annular region  62 , and the tubular string including the apparatus  10 , so that a differential pressure is created between the pressure applied against, inter alia, at least the lower seat  32  and the upper portion of the lower sleeve  28 , and the pressure within the annular region  54 . This differential pressure is increased by, for example, increasing the pressure applied against, inter alia, at least the lower seat  32  and the upper portion of the lower sleeve  28 , so that the shear screws  40  are sheared and thus the lower seat  32  and the lower sleeve  28  move downward, as viewed in  FIG. 17 . The lower sleeve  28  moves downward in the annular region  54  with hydraulic lock being prevented by the ports  18   e , via which the annular region  54  is in fluid communication with the annular region  62 . In several exemplary embodiments, the ports  18   e  are bleed holes that prevent hydraulic lock. 
     With continuing reference to  FIG. 17 , before, during or after the downward movement of the lower seat  32  and the lower sleeve  28  (and the dart  66  if the apparatus  10  is placed in the open configuration mechanically), a fluidic material, such as a hardenable fluidic material  68 , is injected into the apparatus  10  via the tubular string of which the apparatus  10  is a part, and into the internal passage  12   c , the internal passage defined by the upper sleeve  26 , and the internal passage  18   c . The hardenable fluidic material  68  flows out of the apparatus  10  through the ports  18   d  of the outer sleeve  18  and into the annular region  62 . As a result, an annular body of the hardenable fluidic material  68  is formed within the annular region  62 . After the curing of the annular body of the hardenable fluidic material  68  within the annular region  62 , the apparatus  10  and the tubular string of which the apparatus  10  is a part is better supported within the wellbore  60 , and the portion of the annular region  62  or any formation below the annular body of the hardenable fluidic material  68  is fluidically isolated from the portion of the annular region  62  or any formation above the annular body of the hardenable fluidic material  68 . In several exemplary embodiments, the improved support of the apparatus  10  or the tubular string of which the apparatus  10  is a part, or the fluidic isolation of the portion of the annular region  62  or any formation above the annular body of the hardenable fluidic material  68  from the portion of the annular region  62  or the any formation below the annular body, facilitate oil and gas exploration or production operations subsequent to the operation of the apparatus  10 , as described above and below. In an exemplary embodiment, the hardenable fluidic material  68  is, or includes, cement. In an exemplary embodiment, the hardenable fluidic material  68  is, or includes, cement, and the completion of forming (and subsequently curing) the annular body of the material  68  is the completion of one stage in the stage cementing of the tubular string or casing of which the apparatus  10  is a part in the wellbore  60 . 
     As illustrated in  FIG. 18 , before, during or after the curing of the annular body of the hardenable fluidic material  68 , a blocking element such as, for example, a plug  70 , is injected into the apparatus  10  through at least the passage  12   c , until the plug  70  is seated in the upper seat  30 . As a result, the flow of any fluidic materials through the upper sleeve  26  and the remainder of the apparatus  10  therebelow is blocked. Fluidic materials  72  are injected into the apparatus  10 , following the seating of the plug  70  in the upper seat  30 , thereby pressurizing the tubular string of which the apparatus  10  is a part. Continued injection of the fluidic materials  72  causes the respective shear portions  38   d  of the shear screws  38  to shear, at which point the plug  70 , the upper seat  30  and the upper sleeve  26  move downward, as viewed in  FIG. 18 , relative to the outer sleeve  18  and the lower sleeve  28  of the apparatus  10 . Each of the shear portions  38   d  shears along the respective shear plane  38   g . Since the shear plane  38   g  is offset from, and generally parallel to, the flat  38   f  that is tightened against and engages the surface  18   f  of the outer sleeve  18 , or since the shear plane  38   g  extends through the shear portion  38   d  rather than through, for example, the external threaded connection  38   b , a cleaner shear along the shear plane  38   g  is achieved. During the downward movement of the plug  70 , the upper seat  30 , and the upper sleeve  26 , the channels  26   a  of the upper sleeve  26 , the springs  42 , and the lock keys  44  move relative to the fasteners  34 . As a result of the extension of the fasteners  34  into the respective channels  26   a , the fasteners  34  guide the upper sleeve  28  as it moves downward, continuing to prevent or at least resist any relative rotation between the upper sleeve  26  and the outer sleeve  18 . 
     As illustrated in  FIG. 18 a   , during the downward movement of the upper sleeve  26 , each of the lock keys  44  slides against the corresponding fastener  34 , and conversely each of the fasteners  34  continues to engage the side  44   aa  of the corresponding lock key  44 , thereby continuing to energize the corresponding spring  42 . Since each of the fasteners  34  initially engages the side  44   aa  of the corresponding lock key  44  (as shown in  FIG. 13 ), the lock key  44  moves relative to, and slides against, the fastener  34 , and conversely the fastener  34  continues to engage the side  44   aa  of the lock key  44  during this relative movement, as shown in  FIG. 18   a.    
     As illustrated in  FIGS. 19 and 19   a , the plug  70 , the upper seat  30  and the upper sleeve  26  continue to move downward until the fasteners  34  engage the surfaces of the upper sleeve  26  defined by the upper ends of the respective channels  26   a  (shown in  FIG. 19 a   ). As a result of these engagements, the upper sleeve  26  and thus the plug  70  and the upper seat  30  are prevented from moving any further downward. As a result of this downward movement of the plug  70 , the upper seat  30  and the upper sleeve  26 , the apparatus  10  is in a closed configuration in which the ports  18   d  are blocked by the upper sleeve  26  and thus the annular region  62  is fluidically isolated from at least the internal passage  26   e  defined by the upper sleeve  26 . As another result of this downward movement of the plug  70 , the upper seat  30  and the upper sleeve  26 , each of the fasteners  34  is no longer engaging the side  44   aa  of the bar member  44   a  of the respective lock key  44 . As a result, the springs  42  sufficiently relax to push the respective lock keys  44  radially outward within the respective channels  26   a.    
     As a result of the radially outward movement of the lock keys  44 , the lock keys  44  are radially positioned so that each fastener  34  is axially disposed between a surface of the upper sleeve  26  defined by the upper end of the respective channel  26   a  and at least the end portion  44   ad  of the respective lock key  44 , as shown in  FIG. 19 a   . Moreover, each fastener  34  continues to be circumferentially disposed between the vertically-extending side walls of the upper sleeve  26  that are defined by the respective channel  26   a . As a result, the upper sleeve  26  is jammed; the upper sleeve  26  cannot appreciably translate or rotate relative to the lower sleeve  28  or the outer sleeve  18 . 
     The jammed upper sleeve  26  prevents any appreciable upward movement of the lower sleeve  28 , as viewed in  FIG. 19 , and the respective engagements between the fasteners  36  and the surfaces of the lower sleeve  28  defined by the upper ends of the respective channels  28   a  prevent any downward movement of the lower sleeve  28 , as viewed in  FIG. 19 . Moreover, each fastener  36  continues to be circumferentially disposed between the vertically-extending side walls of the lower sleeve  28  that are defined by the respective channel  28   a . As a result, the lower sleeve  28  is jammed; the lower sleeve  28  is not permitted to appreciably translate or rotate relative to the upper sleeve  26  or the outer sleeve  18 . Since neither the upper sleeve  26  nor the lower sleeve  28  is permitted to appreciably rotate or translate relative to each other or the outer sleeve  18 , the apparatus  10  is thus locked in the closed configuration illustrated in  FIG. 19 . This locking of the upper sleeve  26  and the lower sleeve  28  facilitates any drill-out operation of the upper seat  30  and the lower seat  32 . 
     As yet another result of the above-described downward movement of the upper sleeve  26 , the upper sleeve  26  is engaged with the lower sleeve  28  so that lower end portions of the upper sleeve  26  defined by the arcuate notches  26   c  and  26   d  are again interposed between upper end portions of the lower sleeve  28  defined in part by the arcuate notch  28   c ; and axial gaps are defined between axially-facing end surfaces defined by the interposed lower end portions of the upper sleeve  26  and corresponding axially-facing end surfaces defined by the interposed upper end portions of the lower sleeve  28 ; in an exemplary embodiment, grease is disposed in the axial gaps to eliminate any metal-to-metal surface seal. 
     In an exemplary embodiment, after the apparatus  10  has been placed in the closed configuration illustrated in  FIG. 19 , a drill-out operation occurs during which at least the upper seat  30  and the lower seat  32  are drilled out. As noted above, the locking of the upper sleeve  26  and the lower sleeve  28  in the closed configuration illustrated in  FIG. 19  assists in the drill-out operation by preventing the upper sleeve  26  and the lower sleeve  28  from appreciably translating or rotating within the outer sleeve  18  during the drill-out operation. In an exemplary embodiment, after the apparatus  10  has been placed in the closed configuration illustrated in  FIG. 19 , a drill-out operation occurs during which at least the plug  70 , the upper seat  30 , the dart  66  and the lower seat  32  are drilled out. As noted above, the locking of the upper sleeve  26  and the lower sleeve  28  in the closed configuration illustrated in  FIG. 19  assists in the drill-out operation by preventing the upper sleeve  26  and the lower sleeve  28  from appreciably translating or rotating within the outer sleeve  18  during the drill-out operation. 
     In several exemplary embodiments, one or more additional stage tool apparatuses, each of which is substantially similar to the apparatus  10 , are part of the tubular string or casing of which the apparatus  10  is a part. 
     In another embodiment, as illustrated in  FIG. 20  with continuing reference to  FIGS. 1-19   a , the dart  66 , the lower seat  32 , the plug  70 , and the upper seat  30  are omitted from the apparatus  10 . Instead of the dart  66 , the lower seat  32 , the plug  70 , and the upper seat  30 , the exemplary embodiment of the apparatus  10  illustrated in  FIG. 20  includes a dart  74 , a lower seat  76 , a plug  78 , and an upper seat  80 , respectively. 
     In an exemplary embodiment, as illustrated in  FIGS. 21, 21A, 21B, 21C, and 21D  with continuing reference to  FIGS. 1-20 , the dart  74  includes a top body member  74   a  coupled to a bottom body member  74   b . The top body member  74   a  defines an outside surface  74   c , and a plurality of circumferentially-spaced ribs  74   d  extending along the outside surface  74   c . In an exemplary embodiment, the outside surface  74   c  is frusto-conical in shape. In an exemplary embodiment, the outside surface  74   c  and the ribs  74   d  extend downward at a 30 degree angle relative to longitudinal axis  74   da  of the dart  74 . However, the outside surface  74   c  and the ribs  74   d  can extend downward at a variety of angles such as, for example, any angle between 20 degrees and 60 degrees. 
     As shown in  FIG. 21D , the top body member  74   a  includes an internal threaded connection  74   e  that is formed through a bottom surface  74   f . The lower body member  74   b  includes an external threaded connection  74   g  that extends from an upper surface  74   h  of the lower body member  74   b . The internal threaded connection  74   e  is threadably engaged with the external threaded connection  74   g , thereby coupling the top body member  74   a  to the lower body member  74   b . The lower body member  74   b  defines an outside surface  74   i . Proximate the upper surface  74   h , the outside surface  74   i  is cylindrical in shape. As the lower body member  74   b  extends downward, the outside surface  74   i  tapers at a 30 degree angle, relative to the longitudinal axis  74   da  of the dart  74 , towards a nose portion  74   j  of the lower body member  74   b . However, the outside surface  74   i  may taper at a variety of angles such as, for example, any angle between 20 degrees and 60 degrees. An annular channel  74   k  is formed in the portion of the outside surface  74   i  that is cylindrical in shape (proximate the upper surface  74   h ). An annular sealing element, such as an o-ring  74   l , is disposed in the annular channel  74   k . A chamber  74   m , having an opening  74   n , is formed within the lower body member  74   b . In an exemplary embodiment, the chamber  74   m  is formed in the distal axial end of the internal threaded connection  74   g , and extends into the lower body member  74   b  and along the longitudinal axis  74   m , terminating within the nose portion  74   j . In an exemplary embodiment, lead shot or other weighted material is disposed within the chamber  74   m  to ballast the dart  74 . In an exemplary embodiment, the coupling of the top body member  74   a  to the lower body member  74   b  prevents the lead shot that is disposed within the chamber  74   m  from exiting through the opening  74   n . In an exemplary embodiment, the top body member  74   a  has a top surface  74   o.    
     In an exemplary embodiment, the dart  74  is composed of at least one or more non-metallic materials. In an exemplary embodiment, the top body member  74   a  and/or the bottom body member  74   b  is composed of at least one or more non-metallic materials. In an exemplary embodiment, the dart  74  is composed of plastic. In an exemplary embodiment, the dart  74  is composed of phenolic. In an exemplary embodiment, the dart  74  is composed of Durez® 118. In an exemplary embodiment, the dart  74  is composed of Durez® 118 and is filled with lead shot. 
     In an exemplary embodiment, as illustrated in  FIGS. 22 and 22A  with continuing reference to  FIGS. 1-21D , the lower seat  76  includes an annular member  76   a  defining an inside surface  76   b  and an outside surface  76   c . In an exemplary embodiment, the inside surface  76   b  is frusto-conical in shape. A plurality of circumferentially-spaced channels  76   d  are formed in the inside surface  76   b . In an exemplary embodiment, each of the circumferentially-spaced channels  76   d  is sized to accommodate one of the circumferentially-spaced ribs  74   d  of the dart  74 . In an exemplary embodiment, the inside surface  76   b  and the channels  76   d  taper at a 30 degree angle relative to longitudinal axis  76   da  of the lower seat  76 . However, the inside surface  76   b  and the channels  76   d  may taper at a variety of angles such as, for example, any angle between 20 degrees and 60 degrees. The lower seat  76  further defines an inside surface  76   e  extending axially downward from the inside surface  76   b . In an exemplary embodiment, the inside surface  76   e  is cylindrical in shape. In an exemplary embodiment, the outside surface  76   c  tapers inward to form an external shoulder  76   f . The inwardly-tapered external shoulder  76   f  is spaced radially outwardly from the inside surface  76   e . In an exemplary embodiment, the external shoulder  76   f  is configured to mate with the circumferentially-extending shoulder  28   b  to prevent downward movement of the lower seat  76  relative to the lower sleeve  28 . The annular member  76   a  defines a seat passage  76   g . Each of the inside surfaces  76   b  and  76   e  is adjacent the seat passage  76   g.    
     In an exemplary embodiment, the lower seat  76  is composed of at least one or more non-metallic materials. In an exemplary embodiment, the lower seat  76  is composed of plastic. In an exemplary embodiment, the lower seat  76  is composed of phenolic. In an exemplary embodiment, the lower seat  76  is composed of Durez® 118. As shown in  FIG. 20 , the lower seat  76  is disposed in the lower sleeve  28 , with the shoulder  76   f  mating against the shoulder  28   b.    
     In an exemplary embodiment, as illustrated in  FIGS. 23, 23A, 23B, 23C, and 23D  with continuing reference to  FIGS. 1-22A , the plug  78  includes a body member  78   a  defining an outside surface  78   b , and a plurality of circumferentially-spaced ribs  78   c  extending along the outside surface  78   b . In an exemplary embodiment, the outside surface  78   b  is frusto-conical in shape. In an exemplary embodiment, the outside surface  78   b  and the ribs  78   c  taper at a 30 degree angle relative to longitudinal axis  78   ca  of the plug  78 . However, the outside surface  78   b  and the ribs  78   c  may taper at a variety of angles, such as for example, any angle between 20 degrees and 60 degrees. 
     As shown in  FIG. 23D , an external threaded connection  78   d  extends from a top surface  78   e  of the body member  78   a . A core element  78   f  defines a bottom surface  78   g , and includes an internal threaded connection  78   h  formed in the bottom surface  78   g . The internal threaded connection  78   h  is threadably engaged to with external threaded connection  78   d , thereby coupling the core element  78   f  to the body element  78   a . A wiper element  78   i  extends circumferentially around the core element  78   f . In an exemplary embodiment, the wiper element  78   i  includes an inward flange  78   j  that extends between the top surface  78   e  of the body member  78   a  and the bottom surface  78   g  of the core element  78   f . Thus, the coupling of the core element  78   f  to the body element  78   a  secures the wiper element  78   i  to each of the core element  78   f  and the body element  78 . In several exemplary embodiments, one or more adhesives are used to further secure the wiper element  78   i , the core element  78   f , and the body element  78   a  together. The wiper element  78   i  includes a plurality of circumferentially-extending wipers or blades  78   k , which are axially-spaced from one another along the longitudinal axis  78   ca.    
     In an exemplary embodiment, the body member  78   a  is composed of at least one or more non-metallic materials. In an exemplary embodiment, the body member  78   a  is composed of plastic. In an exemplary embodiment, the body member  78   a  is composed of phenolic. In an exemplary embodiment, the body member  78   a  is composed of Durez® 118. In an exemplary embodiment, the core element  78   f  is composed of phenolic. 
     In an exemplary embodiment, as illustrated in  FIGS. 24 and 24A  with continuing reference to  FIGS. 1-23D , the upper seat  80  includes an annular member  80   a  defining an inside surface  80   b  and an outside surface  80   c . In an exemplary embodiment, the inside surface  80   b  is frusto-conical in shape. A plurality of circumferentially-spaced channels  80   d  are formed in the inside surface  80   b . In an exemplary embodiment, each of the circumferentially-spaced channels  80   d  is sized to accommodate one of the circumferentially-spaced ribs  78   c . In an exemplary embodiment, the inside surface  80   b  and the channels  80   d  taper at a 30 degree angle relative to longitudinal axis  80   da  of the upper seat  80 . However, the inside surface  80   b  and the channels  80   d  may taper at a variety of angles such as, for example, any angle between 20 degrees and 60 degrees. The upper seat  80  further defines an inside surface  80   e , which extends axially downward from the inside surface  80   b . In an exemplary embodiment, the inside surface  80   e  is cylindrical in shape. In an exemplary embodiment, the outside surface  80   c  tapers inward to form an external shoulder  80   f . The inwardly-tapered external shoulder  80   f  is spaced radially outwardly from the inside surface  80   e . In an exemplary embodiment, the external shoulder  80   f  is configured to mate with the circumferentially-extending shoulder  26   b  to prevent downward movement of the lower seat  76  relative to the upper sleeve  26 . The annular member  80   a  defines a seat passage  80   g . Each of the inside surfaces  80   b  and  80   e  is adjacent the seat passage  80   g.    
     In an exemplary embodiment, the upper seat  80  is composed of at least one or more non-metallic materials. In an exemplary embodiment, the upper seat  80  is composed of plastic. In an exemplary embodiment, the upper seat  80  is composed of phenolic. In an exemplary embodiment, the upper seat  80  is composed of Durez® 118. As shown in  FIG. 20 , the upper seat  80  is disposed in the upper sleeve  26 , with the shoulder  80   f  mating against the shoulder  26   b.    
     In operation, the embodiment of the apparatus  10  illustrated in  FIG. 20  is identical to the above-described operation of the embodiments of the apparatus  10  illustrated in  FIGS. 1-19   a , subject to operational aspects of the embodiment of the apparatus  10  illustrated in  FIG. 20 , which operational aspects are described below. Similarly to the apparatus  10  illustrated in  FIGS. 1-19   a , the apparatus  10  illustrated in  FIG. 20  is coupled to the box sub  12  and the pin sub  16  while in the assembled position. Additionally, the apparatus  10  illustrated in  FIG. 20  is positioned within the wellbore  60  to define the annular region  62 . As illustrated in  FIG. 25 , the apparatus  10  is in the neutral configuration, in which the lower seat  76  is disposed within the lower sleeve  28 , so that the shoulder  76   f  engages the shoulder  28   b  of the lower sleeve  28  and the upper seat  80  is disposed within the upper sleeve  26 , so that the shoulder  80   f  engages the shoulder  26   b  of the upper sleeve  26 . Additionally, the neutral configuration generally corresponds to the assembled condition previously described above in which, inter alia, the lower sleeve  28  blocks the ports  18   d , which are fluidically isolated from the internal passages  12   c ,  16   c ,  18   c ,  26   e  and  28   e . As a result, the annular region  62  is fluidically isolated from the internal passages  12   c ,  16   c ,  18   c ,  26   e  and  28   e.    
     In an exemplary embodiment, during or after the positioning of the apparatus  10  within the wellbore  60 , the fluidic materials  64  are injected into and circulated through the apparatus  10  via the internal passage  12   c , the internal passage  18   c , the seat passage  80   g , the internal passage  26   e , the internal passage  28   e , the seat passage  76   g , and the internal passage  16   c . In an exemplary embodiment, the fluidic materials  64  may be circulated through and out of the tubular string or casing of which the apparatus  10  is a part and into the wellbore  60 . 
     As illustrated in  FIG. 26 , a blocking element such as, for example, the dart  74 , is injected into the apparatus  10  through at least the passage  12   c  and the internal passage  26   e  defined by the upper sleeve  26  until the dart  74  is seated in the lower seat  76 . As a result, the flow of any fluidic materials, including the fluidic materials  64 , through the seat passage  76   g  and therebelow is prevented or at least partially blocked. 
     In an exemplary embodiment, during operation, as shown in  FIG. 26A , the ribs  74   d  extend within the channels  76   c , respectively, to prevent or at least resist relative rotation between the dart  74  and the lower seat  76 . As shown in  FIG. 26B , the dart  74  has an axial position  82 , relative to the inside surface  76   b  of the lower seat  76 . When the dart  74  is in the axial position  82 , the ribs  74   d  extend within the channels  76   c , respectively, and the o-ring  74   l  sealingly engages the inside surface  76   e . As a result, the flow of any fluidic materials through the seat passage  76   g  is prevented or at least partially blocked. Additionally, the internal passages  12   c  and  26   e  are fluidically isolated from the internal passages  28   c  and  16   c.    
     Continued injection of the fluidic materials  64  into the apparatus  10 , following the seating of the dart  74  in the lower seat  76 , pressurizes the tubular string, of which the apparatus  10  is a part, above the dart  74 . As a result, the fluidic materials  64  exerts a downward force on the top surface  74   o  of the top body  74   a . As a result, the dart  74 , the lower seat  76 , and the lower sleeve  28  are urged downward, relative to at least the outer sleeve  18  and the shear screws  40  (and the wellbore  60 ), so that the radially-extending surface  28   f  of the lower sleeve  28  that is defined by the annular channel  28   d  bears against the shear portions  40   d  of the respective shear screws  40 . Continued injection of the fluidic materials  64  into the apparatus  10 , following the surface  28   f  initially bearing against the shear portions  40   d , causes the respective shear portions  40   d  of the shear screws  40  to shear, at which point the dart  74 , the lower seat  76 , and the lower sleeve  28  move downward, as viewed in  FIG. 27 , relative to the upper sleeve  26  and the outer sleeve  18  of the apparatus  10  and relative to the wellbore  60 . 
     During the downward movement of the dart  74 , the lower seat  76 , and the lower sleeve  28 , the channels  28   a  of the lower sleeve  28  move relative to the fasteners  36 . As a result of the extension of the fasteners  36  into the respective channels  28   a , the fasteners  36  guide the lower sleeve  28  as it moves downward, continuing to prevent or at least resist any relative rotation between the lower sleeve  28  and the outer sleeve  18 . During the downward movement of the dart  74 , the lower seat  76 , and the lower sleeve  28 , the lower end of the lower sleeve  28  is further received by the annular region  54 . 
     As illustrated in  FIG. 27 , the dart  74 , the lower seat  76 , and the lower sleeve  28  continue to move downward until the fasteners  36  engage the surfaces of the lower sleeve  28  defined by the upper ends of the respective channels  28   a . As a result of these engagements, the lower sleeve  28  and thus the dart  74  and the lower seat  76  are prevented from moving any further downward. As a result of the downward movement of the dart  74 , the lower seat  76 , and the lower sleeve  28 , the apparatus  10  is in an open configuration in which the ports  18   d  are not blocked by any of the upper sleeve  26  and the lower sleeve  28  and thus the annular region  62  is in fluid communication with at least the internal passage  12   c , the internal passage  26   e , and the internal passage  18   c  via the ports  18   d . In an exemplary embodiment and while in the open configuration, the o-ring  74   l  continues to sealingly engage the inside surface  76   e  to fluidically isolate the internal passages  12   c  and  26   e  from internal passages  28   c  and  16   c . In an exemplary embodiment and while in the open configuration, the dart  74  continues to prevent or at least partially block the flow of any fluidic materials through the seat passage  76   g  and into the internal passage  26   e.    
     With continuing reference to  FIG. 27 , during or after the downward movement of the lower seat  76  and the lower sleeve  28 , a fluidic material, such as the hardenable fluidic material  68 , is injected into the apparatus  10  via the tubular string of which the apparatus  10  is a part, and into the internal passage  12   c . The hardenable fluidic material  68  flows out of the apparatus  10  through the ports  18   d  of the outer sleeve  18  and into the annular region  62 . As a result, an annular body of the hardenable fluidic material  68  is formed within the annular region  62 . In an exemplary embodiment and while the hardenable fluidic material  68  flows out of the apparatus  10  through the ports  18   d , the o-ring  74   l  continues to sealingly engage the inside surface  76   e  to fluidically isolate the internal passages  12   c  and  26   e  from internal passages  28   c  and  16   c . In an exemplary embodiment and while the hardenable fluidic material  68  flows out of the apparatus  10  through the ports  18   d , the dart  74  continues to block the flow of any fluidic materials through the seat passage  76   g  and into the internal passage  26   e.    
     As illustrated in  FIG. 28 , before, during, or after the curing of the annular body of the hardenable fluidic material  68 , a blocking element such as, for example, the plug  78 , is injected into the apparatus  10  through at least the passage  12   c , until the plug  78  is seated in the upper seat  80 . As a result, the flow of any fluidic materials through the seat passage  80   g , the upper sleeve  26 , and the remainder of the apparatus  10  therebelow is blocked. Fluidic materials  72  are injected into the apparatus  10 , following the seating of the plug  78  in the upper seat  80 , thereby pressurizing the tubular string of which the apparatus  10  is a part. Continued injection of the fluidic materials  72  causes the respective shear portions  38   d  of the shear screws  38  to shear, at which point the plug  78 , the upper seat  80 , and the upper sleeve  26  move downward, as viewed in  FIG. 18 , relative to the outer sleeve  18  and the lower sleeve  28  of the apparatus  10  and relative to the wellbore  60 . Each of the shear portions  38   d  shears along the respective shear plane  38   g . During the downward movement of the plug  78 , the upper seat  80 , and the upper sleeve  26 , the channels  26   a  of the upper sleeve  26 , the springs  42 , and the lock keys  44  move relative to the fasteners  34 . As a result of the extension of the fasteners  34  into the respective channels  26   a , the fasteners  34  guide the upper sleeve  28  as it moves downward, continuing to prevent or at least resist any relative rotation between the upper sleeve  26  and the outer sleeve  18 . In an exemplary embodiment, during operation, as shown in  FIG. 28A , the ribs  78   c  extend within the channels  80   d , respectively, to prevent or at least resist relative rotation between the plug  78  and the upper seat  80 . 
     As illustrated in  FIG. 29 , the plug  78 , the upper seat  80 , and the upper sleeve  26  continue to move downward until the fasteners  34  engage the surfaces of the upper sleeve  26  defined by the upper ends of the respective channels  26   a  (shown in  FIG. 19 a   ). As a result of these engagements, the upper sleeve  26  and thus the plug  78  and the upper seat  80  are prevented from moving any further downward. As a result of this downward movement of the plug  78 , the upper seat  80 , and the upper sleeve  26 , the apparatus  10  is in the closed configuration in which the ports  18   d  are blocked by the upper sleeve  26  and thus the annular region  62  is fluidically isolated from at least the internal passage  26   e  defined by the upper sleeve  26 . As another result of this downward movement of the plug  78 , the upper seat  80 , and the upper sleeve  26 , each of the fasteners  34  is no longer engaging the side  44   aa  of the bar member  44   a  of the respective lock key  44  (shown in  FIG. 19 a   ). As a result, the springs  42  sufficiently relax to push the respective lock keys  44  radially outward within the respective channels  26   a.    
     As a result of the radially outward movement of the lock keys  44 , the lock keys  44  are radially positioned so that each fastener  34  is axially disposed between a surface of the upper sleeve  26  defined by the upper end of the respective channel  26   a  and at least the end portion  44   ad  of the respective lock key  44 , as shown in  FIG. 19 a   . Moreover, each fastener  34  continues to be circumferentially disposed between the vertically-extending side walls of the upper sleeve  26  that are defined by the respective channel  26   a . As a result, the upper sleeve  26  is jammed; the upper sleeve  26  cannot appreciably translate or rotate relative to the lower sleeve  28  or the outer sleeve  18 . 
     The jammed upper sleeve  26  prevents any appreciable upward movement of the lower sleeve  28 , as viewed in  FIG. 29 , and the respective engagements between the fasteners  36  and the surfaces of the lower sleeve  28  defined by the upper ends of the respective channels  28   a  prevent any downward movement of the lower sleeve  28 , as viewed in  FIG. 29 . Moreover, each fastener  36  continues to be circumferentially disposed between the vertically-extending side walls of the lower sleeve  28  that are defined by the respective channel  28   a . As a result, the lower sleeve  28  is jammed; the lower sleeve  28  is not permitted to appreciably translate or rotate relative to the upper sleeve  26  or the outer sleeve  18 . Since neither the upper sleeve  26  nor the lower sleeve  28  is permitted to appreciably rotate or translate relative to each other or the outer sleeve  18 , the apparatus  10  is thus locked in the closed configuration illustrated in  FIG. 29 . This locking of the upper sleeve  26  and the lower sleeve  28  facilitates any drill-out operation of the upper seat  80  and the lower seat  76 . 
     As yet another result of the above-described downward movement of the upper sleeve  26 , the upper sleeve  26  is engaged with the lower sleeve  28  so that lower end portions of the upper sleeve  26  defined by the arcuate notches  26   c  and  26   d  are again interposed between upper end portions of the lower sleeve  28  defined in part by the arcuate notch  28   c ; and axial gaps are defined between axially-facing end surfaces defined by the interposed lower end portions of the upper sleeve  26  and corresponding axially-facing end surfaces defined by the interposed upper end portions of the lower sleeve  28 ; in an exemplary embodiment, grease is disposed in the axial gaps to eliminate any metal-to-metal surface seal. 
     As a result of the ribs  78   c  extending within the channels  80   d , as shown in  FIG. 28A , relative rotation between the plug  78  and the upper seat  80  is prevented or at least resisted. In an exemplary embodiment, the resulting prevention or resistance of relative rotation between the plug  78  and the upper seat  80  facilitates any drill-out operation during which the plug  78 , the upper seat  80 , the dart  74 , and the lower seat  76  are drilled out. Similarly, as a result of the ribs  74   d  extending within the channels  76   c , as shown in  FIG. 26A , the resulting prevention or resistance of relative rotation between the dart  74  and the lower seat  76  facilitates any drill-out operation during which the plug  78 , the upper seat  80 , the dart  74  and the lower seat  76  are drilled out. 
     In several exemplary embodiments, the non-metallic material(s) of which the lower seat  76  are composed facilitate the drill out of the lower seat  76 . The non-metallic material(s), of which the dart  74  or at least the body member  74   a  thereof are composed, facilitate the drill out of the dart  74 . The non-metallic material(s), of which at least the body member  78   a  of the plug  78  are composed, facilitate the drill out of the plug  78 . The non-metallic material(s), of which the upper seat  80  are composed, facilitate the drill out of the upper seat  80 . When compared with metallic materials, the non-metallic material(s) may be less resistant to drill-out operations, increasing the speed at which the apparatus  10  may be drilled out. 
     In another exemplary embodiment and as illustrated in  FIGS. 30, 30A, and 30B , the ribs  74   d  of the dart  74  do not initially extend within the channels  76   c  of the lower seat  76 , respectively, when the apparatus  10  is in the closed configuration. Instead, the ribs  74   d  engage the inside surface  76   b . As a result, and as shown in  FIG. 30B , the dart  74  has an axial position  84 , relative to the inside surface  76   b  of the lower seat  76 . When the dart  74  is in the axial position  84 , the ribs  74   d  do not extend within the channels  76   c , respectively, but the o-ring  74   l  still sealingly engages the inside surface  76   e . Thus, the o-ring  74   l  sealingly engages the inside surface  76   e  when the dart  74  is in either the axial position  82  or the axial position  84 . At the axial position  84 , the o-ring  74   l  is closer to the lower ends of the channels  76   c , than when the dart  74  is in the axial position  82 , because the ribs  74   d  are contacting the inside surface  76   b , rather than extending within the channels  76   c . However, even if the ribs  74   d  do not initially extend within the channels  76   c , respectively, in several exemplary embodiments, during a drill-out operation the dart  74  may undergo rotation, relative to the lower seat  76 , which rotation may cause the ribs  74   d  to extend within the channels  76   c , respectively. Such extensions may facilitate the remainder of the drill-out operation, increasing the speed at which the apparatus  10  may be drilled out. 
     In another exemplary embodiment and as illustrated in  FIG. 31 , the ribs  78   c  of the plug  78  do not initially extend within the channels  80   d  of the upper seat  80 , respectively. Instead, the ribs  78   c  contact or are otherwise engaged with the inside surface  80   b . However, even if the ribs  78   c  do not initially extend within the channels  80   d , respectively, during a drill-out operation the plug  78  may undergo rotation, relative to the upper seat  80 , which rotation may cause the ribs  78   c  to extend within the channels  80   d , respectively. Such extensions may facilitate the remainder of the drill-out operation, increasing the speed at which the apparatus  10  may be drilled out. 
     In an exemplary embodiment, any two or more of the outside surfaces  74   c  and  78   b  and the inside surfaces  76   b  and  80   b  taper at equal angles to encourage the engagement of the outside surface  74   c  to the inside surface  76   b  and the engagement of the outside surface  78   b  to the inside surface  80   b . However in another exemplary embodiment, two or more of the outside surfaces  74   c  and  78   b  and the inside surfaces  76   b  and  80   b  taper at different angles and the outside surface  74   c  still engages the inside surface  76   b  and the outside surface  78   b  still engages the inside surface  80   b . In an exemplary embodiment, any two or more of the ribs  74   d  and  78   c  and the channels  76   d  and  80   d  taper at equal angles to encourage the engagement of the ribs  74   d  to the channels  78   d , respectively, and the engagement of the ribs  78   c  to the channels  80   d , respectively. However in another exemplary embodiment, any two or more of the ribs  74   d  and  78   c  and the channels  76   d  and  80   d  taper at different angles and the ribs  74   d  still engage the channels  76   d , respectively, and the ribs  78   c  still engage the channels  80   d , respectively. 
     In several exemplary embodiments, the apparatus  10  illustrated in  FIGS. 20-31  or any component thereof includes, in whole or in part, one or more embodiments or portions thereof disclosed in U.S. patent application Ser. No. 12/898,444, filed Oct. 5, 2010, the entire disclosure of which is incorporated herein by reference. 
     A stage tool apparatus for forming an annular body of a fluidic material in an annular region that is partially defined by a preexisting structure has been described that includes a first seat, including: a first annular member defining a first seat passage and a first inside surface adjacent the first seat passage; and a plurality of circumferentially-spaced first channels formed in the first inside surface of the first annular member; and a first blocking element adapted to engage the first seat, the first blocking element including: a first body member defining a first outside surface; and a plurality of circumferentially-spaced first ribs extending along the first outside surface of the first body member; wherein the first blocking element engages the first seat so that the fluidic material is at least partially blocked from flowing through the first seat passage; and wherein the first ribs extend within the first channels, respectively, to resist relative rotation between the first seat and the first blocking element. In an exemplary embodiment, the preexisting structure is a wellbore that traverses a subterranean formation. In an exemplary embodiment, the first blocking element defines a second outside surface and further includes: an annular channel formed in the second outside surface; and an annular sealing element disposed in the annular channel and adapted to sealingly engage the first seat; wherein the first blocking element has: a first axial position, relative to the first seat, in which the first ribs do not extend within the first channels, respectively; and a second axial position, relative to the first seat, in which the first ribs do extend within the first channels, respectively; and wherein the annular sealing element sealing engages the first seat when the first blocking element is in either the first axial position or the second axial position. In an exemplary embodiment, each of the first inside surface and the first outside surface has a frusto-conical shape; wherein the second outside surface has a cylindrical shape; wherein the first seat further defines a second inside surface that extends axially from the first inside surface, the second inside surface having a cylindrical shape and being adjacent the first seat passage; and wherein the annular sealing element sealingly engages the second inside surface of the first seat when the first blocking element is in either the first axial position or the second axial position. In an exemplary embodiment, the stage tool apparatus includes a second seat spaced axially from the first seat, including: a second annular member defining a second seat passage and a third inside surface adjacent the second seat passage; and a plurality of circumferentially-spaced second channels formed in the third inside surface of the second annular member; and a second blocking element adapted to engage the second seat, the second blocking element including: a second body member defining a third outside surface; and a plurality of circumferentially-spaced second ribs extending along the third outside surface of the second body member; wherein the second blocking element engages the second seat so that the fluidic material is at least partially blocked from flowing through the second seat passage; and wherein the second ribs extend within the second channels, respectively, to resist relative rotation between the second seat and the second blocking element. In an exemplary embodiment, each of the first seat, the first body member, the second seat, and the second body member is composed of at least one or more non-metallic materials. In an exemplary embodiment, the first blocking element is a dart and the second blocking element is a plug. In an exemplary embodiment, the stage tool apparatus includes a first tubular member defining a first internal passage, wherein the outside surface of the first tubular member is adapted to partially define the annular region; a second tubular member defining a second internal passage, the second tubular member extending within the first internal passage; wherein the first seat is disposed in the second tubular member; wherein the second tubular member is movable, relative to the first tubular member, from a first position to a second position; wherein the first tubular member includes a flow port that is blocked by the second tubular member when the second tubular member is in the first position; and wherein the flow port is not blocked by the second tubular member when the second tubular member is in the second position. In an exemplary embodiment, the stage tool apparatus includes a third tubular member defining a third internal passage, the third tubular member extending within the first internal passage; wherein the second seat is disposed in the third tubular member; wherein the third tubular member is movable, relative to the first tubular member, from a third position to a fourth position; wherein the flow port is not blocked by the third tubular member when the third tubular member is in the third position; and wherein the flow port is blocked by the third tubular member when the third tubular member is in the fourth position. 
     A kit for a downhole tool has been described that includes a first seat adapted to be positioned in the downhole tool, the first seat including: a first annular member defining a first seat passage and a first inside surface adjacent the first seat passage; and a plurality of circumferentially-spaced first channels formed in the first inside surface of the first annular member; and a first blocking element adapted to engage the first seat when the first seat is positioned in the downhole tool, the first blocking element including: a first body member defining a first outside surface; and a plurality of circumferentially-spaced first ribs extending along the first outside surface of the first blocking element and adapted to extend within the first channels, respectively; wherein, when the first seat is positioned in the downhole tool, the first blocking element engages the first seat, and the first ribs extend within the first channels, respectively, relative rotation between the first seat and the first blocking element is resisted; and wherein, when the first seat is positioned in the downhole tool and the first blocking element engages the first seat, a fluidic material is at least partially blocked from flowing through the first seat passage. In an exemplary embodiment, the kit includes a second seat adapted to be positioned in the downhole tool and axially spaced from the first seat when the first and second seats are positioned in the downhole tool, the second seat including: a second annular member defining a second seat passage and a second inside surface adjacent the second seat passage; and a plurality of circumferentially-spaced second channels formed in the second inside surface of the second annular member; and a second blocking element adapted to engage the second seat when the second seat is positioned in the downhole tool, the second blocking element including: a second body member defining a second outside surface; and a plurality of circumferentially-spaced second ribs extending along the second outside surface of the second body member and adapted to extend within the second channels, respectively; wherein, when the second seat is positioned in the downhole tool, the second blocking element engages the second seat, and the second ribs extend within the second channels, respectively, relative rotation between the second seat and the second blocking element is resisted; and wherein, when the second seat is positioned in the downhole tool and the second blocking element engages the second seat, the fluidic material is at least partially blocked from flowing through the second seat passage. In an exemplary embodiment, the downhole tool is a stage tool apparatus for forming an annular body of the fluidic material in an annular region that is partially defined by a wellbore that traverses a subterranean formation; wherein the first blocking element is a dart; wherein the second blocking element is a plug; wherein, when the first and second seats are positioned in the stage tool apparatus and the dart engages the first seat, the first seat is adapted to move, relative to the second seat; and wherein, when the first and second seats are positioned in the stage tool apparatus and the plug engages the second seat, the second seat is adapted to move, relative to the first seat. In an exemplary embodiment, each of the first seat, the first body member, the second seat, and the second body member is composed of at least one or more non-metallic materials. In an exemplary embodiment, the first blocking element defines a third outside surface and further includes: an annular channel formed in the third outside surface; and an annular sealing element disposed in the annular channel and adapted to sealingly engage the first seat; wherein the first blocking element has: a first axial position, relative to the first seat, in which the first ribs do not extend within the first channels, respectively; and a second axial position, relative to the first seat, in which the first ribs do extend within the first channels, respectively; and wherein the annular sealing element sealing engages the first seat when the first blocking element is in either the first axial position or the second axial position. In an exemplary embodiment, each of the first inside surface and the first outside surface has a frusto-conical shape; wherein the third outside surface has a cylindrical shape; wherein the first seat further defines a third inside surface that extends axially from the first inside surface, the third inside surface having a cylindrical shape and being adjacent the first seat passage; and wherein the annular sealing element sealingly engages the third inside surface when the first blocking element is in either the first axial position or the second axial position. 
     A blocking element has been described wherein the blocking element is adapted to engage a seat positioned within a downhole tool, the seat including: an annular member defining a seat passage, a first inside surface having a frusto-conical shape, and a second inside surface extending axially from the first inside surface and having a cylindrical shape, the first and second inside surfaces being adjacent the seat passage, and a plurality of circumferentially-spaced channels formed in the first inside surface of the annular member. The blocking element includes: a body member defining a first outside surface, the first outside surface having a frusto-conical shape; and a plurality of circumferentially-spaced ribs extending along the first outside surface of the body member; wherein the blocking element is adapted to engage the seat so that a fluidic material is at least partially blocked from flowing through the seat passage; and wherein the ribs are adapted to extend within the channels, respectively, to resist relative rotation between the seat and the blocking element. In an exemplary embodiment, the blocking element defines a second outside surface, the second outside surface having a cylindrical shape; wherein the blocking element further includes: an annular channel formed in the second outside surface; and an annular sealing element disposed in the annular channel and adapted to sealingly engage the seat; wherein the blocking element is adapted to have: a first axial position, relative to the seat, in which the ribs do not extend within the channels, respectively; and a second axial position, relative to the seat, in which the ribs do extend within the channels, respectively; and wherein the annular sealing element is adapted to sealingly engage the second inside surface of the seat when the blocking element is in either the first axial position or the second axial position. In an exemplary embodiment, the downhole tool is a stage tool apparatus for forming an annular body of a fluidic material in an annular region that is partially defined by a wellbore that traverses a subterranean formation; wherein the blocking element is a plug and further includes a plurality of wiper elements connected to the body member; and wherein the body member is composed of at least one or more non-metallic materials. 
     A seat has been described wherein the seat is adapted to be positioned in a downhole tool and engage one of a dart and a plug when positioned in the downhole tool, the one of the dart and the plug including: a body member defining an outside surface, the outside surface having a frusto-conical shape, and a plurality of circumferentially-spaced ribs extending along the outside surface of the body member. The seat includes an annular member defining: a seat passage; a first inside surface adjacent the seat passage, the first inside surface having a frusto-conical shape; a second inside surface extending axially from the first inside surface, the second inside surface having a cylindrical shape and being adjacent the seat passage; and an inwardly-tapered external shoulder spaced radially outwardly from the second inside surface and adapted to engage another shoulder when positioned in the downhole tool; and a plurality of circumferentially-spaced channels formed in the first inside surface of the annular member; wherein the blocking element is adapted to engage the seat so that a fluidic material is at least partially blocked from flowing through the seat passage; and wherein the ribs are adapted to extend within the channels, respectively, to resist relative rotation between the seat and the one of the dart and the plug. In an exemplary embodiment, the downhole tool is a stage tool apparatus for forming an annular body of the fluidic material in an annular region that is partially defined by a wellbore that traverses a subterranean formation; and wherein the seat is composed of at least one or more non-metallic materials. 
     It is understood that variations may be made in the foregoing without departing from the scope of the disclosure. 
     In several exemplary embodiments, the elements and teachings of the various illustrative exemplary embodiments may be combined in whole or in part in some or all of the illustrative exemplary embodiments. In addition, one or more of the elements and teachings of the various illustrative exemplary embodiments may be omitted, at least in part, or combined, at least in part, with one or more of the other elements and teachings of the various illustrative embodiments. 
     Any spatial references such as, for example, “upper,” “lower,” “above,” “below,” “between,” “bottom,” “vertical,” “horizontal,” “angular,” “upwards,” “downwards,” “side-to-side,” “left-to-right,” “left,” “right,” “right-to-left,” “top-to-bottom,” “bottom-to-top,” “top,” “bottom,” “bottom-up,” “top-down,” etc., are for the purpose of illustration only and do not limit the specific orientation or location of the structure described above. 
     In several exemplary embodiments, while different steps, processes, and procedures are described as appearing as distinct acts, one or more of the steps, one or more of the processes, or one or more of the procedures may also be performed in different orders, simultaneously or sequentially. In several exemplary embodiments, the steps, processes or procedures may be merged into one or more steps, processes or procedures. In several exemplary embodiments, one or more of the operational steps in each embodiment may be omitted. Moreover, in some instances, some features of the present disclosure may be employed without a corresponding use of the other features. Moreover, one or more of the above-described embodiments or variations may be combined in whole or in part with any one or more of the other above-described embodiments or variations. 
     Although several exemplary embodiments have been disclosed in detail above, the embodiments disclosed are exemplary only and are not limiting, and those skilled in the art will readily appreciate that many other modifications, changes and/or substitutions are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the present disclosure. Accordingly, all such modifications, changes and/or substitutions are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.