Abstract:
An apparatus for reaming a wellbore without rotating a tubular string that is extendable to a surface. A mandrel ( 102 ) is coupled to a downhole end of the tubular string. The mandrel ( 102 ) has at least one groove ( 110 ) in a sidewall portion thereof. A sleeve ( 112 ) is operably associated with the mandrel ( 102 ) such that longitudinal travel of the mandrel ( 102 ) relative to the sleeve ( 112 ) shifts the sleeve ( 112 ) between extended and contracted positions relative to the mandrel ( 102 ). A reamer shoe ( 122 ) is coupled to a downhole end of the sleeve ( 112 ). At least one coupling device ( 116 ) is operably associated with the sleeve ( 112 ) and extendable into the at least one groove ( 110 ) such that longitudinal travel of the mandrel ( 102 ) relative to the sleeve ( 112 ) caused the sleeve ( 112 ) to rotate relative to the mandrel ( 102 ), thereby rotating the reamer shoe ( 122 ).

Description:
FIELD OF THE INVENTION 
     This invention relates, in general, to equipment utilized in conjunction with operations performed in subterranean wells and, in particular, to an apparatus and method for reaming a wellbore during the installation of a tubular string without rotating the tubular string. 
     BACKGROUND OF THE INVENTION 
     Without limiting the scope of the present invention, its background is described with reference to constructing a subterranean well including a liner string, as an example. 
     In conventional practice, the drilling of an oil or gas well involves creating a wellbore that traverses numerous subterranean formations. For a variety reasons, each of the formations through which the well passes is preferably sealed. For example, it is important to avoid an undesirable passage of formation fluids, gases or materials out of the formation and into the wellbore or for wellbore fluids to enter the formation. In addition, it is commonly desired to isolate producing formations from nonproducing formations to avoid contaminating one formation with the fluids from another formation. 
     To avoid these problems, conventional well architecture includes the installation of casing within the wellbore. In addition to providing the sealing function, the casing also provides wellbore stability to counteract the geomechanics of the formation such as compaction forces, seismic forces and tectonic forces, thereby preventing the collapse of the wellbore wall. In standard practice, each succeeding casing string placed in the wellbore has an outside diameter having a reduced size when compared to the previously installed casing string. Specifically, the wellbore is drilled in intervals whereby a casing, which is to be installed in a lower wellbore interval, must be passed through the previously installed casing string in an upper wellbore interval. 
     The casings are generally fixed within the wellbore by a cement layer between the outer wall of the casing and the wall of the wellbore. During the drilling of the wellbore, annuli are provided between the outer surfaces of the casings and the wellbore wall. When a casing string is located in its desired position in the well, a cement slurry is pumped via the interior of the casing, around the lower end of the casing and upwards into the annulus. As soon as the annulus around the casing is sufficiently filled with the cement slurry, the cement slurry is allowed to harden. The cement sets up in the annulus, supporting and positioning the casing and forming a substantially impermeable barrier which divides the wellbore into subterranean zones. 
     In one approach, each casing string extends downhole from the surface such that only a lower section of each casing string is adjacent to the wellbore wall. Alternatively, the wellbore casings may include one or more liner strings, which do not extend to the surface of the wellbore, but instead typically extend from near the downhole end of a previously installed casing downward into the uncased portion of the wellbore. Liner strings are typically lowered downhole on a work string that may include a drill pipe string and a running tool that attaches to the liner string. The liner string typically includes a liner hanger at its uphole end that may be mechanically or hydraulically set. 
     Preferably, the liner string is set or suspended by the liner hanger at a location in the wellbore so that the downhole end of the liner string extends to close proximity of the bottom of the wellbore. It has been found, however, that in certain wellbores such as deviated wellbores, horizontal wellbores, multilateral wellbores and the like, it is difficult to work the liner string to the bottom of the wellbore. For example, during drilling of the lowermost section of the wellbore and the installation of the liner string, debris may build up near the bottom of the wellbore, which prevents installation of the liner string at the desired depth. Attempts have been made to use a conventional reamer shoe at the lower end of the liner string such that rotation of the liner string will allow the cutting structure of the reamer shoe to penetrate through the debris. It has been found, however, that in certain deep wells including the aforementioned deviated wellbores, horizontal wellbores, multilateral wellbores and the like, the torque capacity of the drilling rig, the liner threads or both, limits the ability to rotate the liner string. Accordingly, a need has arisen for an apparatus and method for reaming a wellbore during the installation of a liner string without the requirement of rotating the liner string. 
     SUMMARY OF THE INVENTION 
     The present invention disclosed herein is directed to an apparatus for reaming a wellbore during the installation of a tubular string without rotating the tubular string. More specifically, the apparatus and method of the present invention utilize a reamer shoe that does not require rotation of the tubular string during installation but instead utilizes a rotatable sleeve to rotate the reamer shoe. 
     In one aspect, the present invention is directed to an apparatus for reaming a wellbore without rotating the tubular string that extends to the surface of the wellbore. The apparatus includes a mandrel that is coupled to the downhole end of the tubular string. A sleeve is operably associated with the mandrel such that longitudinal travel of the mandrel relative to the sleeve rotates the sleeve relative to the mandrel. A reamer shoe is coupled to a downhole end of the sleeve such that rotation of the sleeve rotates the reamer shoe. 
     In one embodiment, the tubular string may be a liner string, a casing string or the like. In another embodiment, the mandrel includes at least one groove, such as a plurality of spiral grooves or a J-slot, cut in a sidewall portion of the mandrel, such as the inner or outer surface of the mandrel. In this embodiment, a coupling device that is operably associated with the sleeve and extendable into the at least one groove translates the longitudinal travel of the mandrel relative to the sleeve into rotation of the sleeve and the reamer shoe relative to the mandrel. In certain embodiments, a biasing member may be used to urge the sleeve from a contracted position toward an extended position. In this embodiment, at least one of the mandrel and the sleeve may have at least one slot in a sidewall portion thereof. In another embodiment, the reamer shoe may include a cutting structure, at least one flow port or both. 
     In another aspect, the present invention is directed to an apparatus for reaming a wellbore. The apparatus includes a drill pipe string extendable to the surface of the wellbore. A liner string is coupled to the downhole end of the drill pipe string. A mandrel is coupled to the downhole end of the liner string. The mandrel includes at least one groove cut in an outer surface of a sidewall portion thereof. A sleeve is at least partially position about the exterior of the mandrel such that longitudinal travel of the mandrel relative to the sleeve shifts the sleeve between an extended position and a contracted position relative to the mandrel. A reamer shoe is coupled to the downhole end of the sleeve. At least one coupling device is operably associated with the sleeve and extendable into the at least one groove such that the longitudinal travel of the mandrel relative to the sleeve caused the sleeve to rotate relative to the mandrel, thereby rotating the reamer shoe. 
     In another aspect, the present invention is directed to a method for reaming a wellbore. The method includes coupling a reamer assembly to a tubular string, the reamer assembly includes a mandrel, a sleeve operably associated with the mandrel and a reamer shoe coupled to the sleeve, running the tubular string into the wellbore until the reamer shoe contacts a restriction in the wellbore, applying weight on the reamer shoe via the tubular string, longitudinally contracting the reamer assembly to rotate the sleeve relative to the mandrel, thereby rotating the reamer shoe, reducing the weight applied to the reamer shoe and longitudinally extending the reamer assembly. 
     The method may also include coupling the reamer assembly to a liner string, a casing string or the like, sliding a coupling device operably associated with the sleeve in a groove cut in a surface of the mandrel, sliding the coupling device in the groove cut in an outer surface of the mandrel, urging the sleeve toward the extended position of the reamer assembly with a biasing member and urging the sleeve toward the extended position of the reamer assembly by pumping a fluid through at least one flow port of the reamer shoe. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: 
         FIG. 1  is a schematic illustration of an offshore oil and gas platform operating an apparatus for reaming a wellbore according to an embodiment of the present invention; 
         FIG. 2  is a side view of a reamer assembly in its extended configuration for use in an apparatus for reaming a wellbore according to an embodiment of the present invention; 
         FIG. 3  is a top view of a reaming bit for use in an apparatus for reaming a wellbore according to an embodiment of the present invention; 
         FIG. 4  is a side view of the reamer assembly of  FIG. 2  in its contracted configuration; 
         FIG. 5  is a side view of a reamer assembly for use in an apparatus for reaming a wellbore according to an embodiment of the present invention; 
         FIG. 6  is a side view, partially cut away, of a reamer assembly for use in an apparatus for reaming a wellbore according to an embodiment of the present invention; and 
         FIG. 7  is a side view, partially cut away, of a reamer assembly for use in an apparatus for reaming a wellbore according to an embodiment of the present invention; 
         FIG. 8  is a side view, partially cut away, of a reamer assembly for use in an apparatus for reaming a wellbore according to an embodiment of the present invention; and 
         FIG. 9  is a side view of a reamer assembly for use in an apparatus for reaming a wellbore according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention. 
     Referring initially to  FIG. 1 , an apparatus for reaming a wellbore being deployed from an offshore platform is schematically illustrated and generally designated  10 . A semi-submersible platform  12  is centered over submerged oil and gas formation  14  located below sea floor  16 . A subsea conduit  18  extends from deck  20  of platform  12  to wellhead installation  22 , including blowout preventers  24 . Platform  12  has a hoisting apparatus  26 , a derrick  28 , a travel block  30 , a hook  32  and a swivel  34  for raising and lowering pipe strings, such as a liner string  36 . 
     A wellbore  38  extends through the various earth strata including formation  14 . An upper portion of wellbore  38  includes casing  40  that is cemented within wellbore  38  by cement  42 . Disposed within the lower portion of wellbore  38  is liner string  36 . Liner string  36  is being lowered downhole on a work string  44  that includes a setting tool  46  that attaches work string  44  to liner string  36 . Preferably, the upper portion of work string  44  is formed from a drill pipe string or similar tubular members. Liner string  36  includes a liner hanger  48  at its uphole end that is operable to be set by setting tool  46 . 
     A reamer assembly  50  is coupled to the downhole end of liner string  36 . As shown, liner string  36  has been run in wellbore  38  to a position in which reamer assembly  50  has come in contact with debris  52  which has built up in the bottom of wellbore  38 . This debris  52  makes it difficult to work liner string  36  to its desired location proximate the bottom of wellbore  38 . Use of the present invention, however, enables liner string  36  to be positioned as desired. Specifically, reamer assembly  50  is used to clear debris  52  from the bottom of wellbore  38 . Reamer assembly  50  is operated without the need to provide torque from the surface via rotating working string  44  and liner string  36 . Instead, reamer assembly  50  of the present invention is rotatable responsive to the application of a compressive force applied to reamer assembly  50 . This compressive force may be delivered via the application of a longitudinal force in the downhole direction from the surface via liner string  36  and work string  44  to operate reamer assembly  50  of the present invention as described in greater detail below. 
     Even though  FIG. 1  depicts a deviated wellbore, it should be understood by those skilled in the art that the apparatus for reaming a wellbore of the present invention is equally well suited for use in wellbores having other directional orientations including vertical 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, below, upper, lower, upward, downward, uphole, downhole and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the uphole direction being toward the top or the left of the corresponding figure and the downhole direction being toward the bottom or the right of the corresponding figure. Also, even though  FIG. 1  depicts an offshore operation, it should be understood by those skilled in the art that the apparatus for reaming a wellbore of the present invention is equally well suited for use in onshore operations. 
     Referring next to  FIG. 2 , therein is depicted a reamer assembly  100  for use in an apparatus for reaming a wellbore according to the present invention. Reamer assembly  100  is used to clear the bottom of a wellbore of debris or open a restriction encountered during the installation of a tubular string such as a casing string or liner string in a wellbore that has been previously drilled. Reamer assembly  100  includes a mandrel  102  that preferably includes a box end  104  for threadably coupling mandrel  102  with the lower end of a tubular string. In the illustrated embodiment, mandrel  102  includes a radially expanded section  106  that defines a shoulder  108 . As illustrated, mandrel  102  has four spiral grooves  110  forming a plurality of turns around the outer surface of mandrel  102 . Preferably, spiral grooves  110  take the form of helical curves. Even though reamer assembly  100  has be depicted as having a mandrel with four spiral grooves, it should be understood by those skilled in the art that reamer assembly  100  could alternatively have a mandrel with a greater number or lesser number of spiral grooves including a single spiral groove. In addition, even though reamer assembly  100  has be depicted as having a mandrel with spiral grooves formed in the outer surface, it should be understood by those skilled in the art that reamer assembly  100  could alternatively have a mandrel with spiral grooves formed in the inner surface. 
     Reamer assembly  100  includes a sleeve  112 . In the illustrated embodiment, sleeve  112  is partially positioned around mandrel  102  and is sized such that mandrel  102  can move longitudinally within sleeve  112 . In other embodiments, such as those embodiments in which the spiral grooves are formed in the inner surface of mandrel  102 , sleeve  112  could alternative be positioned partially within mandrel  102  and sized such that mandrel  102  could move longitudinally along the exterior of sleeve  112 . Sleeve  112  has a plurality of openings  114  that are preferably threaded. A pin  116  is securably received within each of the openings  114  such that pins  116  extend into spiral grooves  110  to secure sleeve  112  and mandrel  102  together. At its upper end, sleeve  112  defines a shoulder  118 . Preferably, sleeve  112  has a box end  120  for threadably coupling sleeve  112  with the upper end of a reamer shoe  122 . Positioned around mandrel  102  and between shoulder  108  of mandrel  102  and shoulder  118  of sleeve  112  is a biasing member depicted as a spiral wound compression spring  132  that urges sleeve  102  in the downhole direction away from radially expanded section  106  of mandrel  102 . Even though a particular type of biasing member has been depicted and described, those skilled in the art will recognize that other types of biasing members, such as wave springs, spring stacks and the like could alternatively be used in conjunction with the present invention. 
     As best seen in  FIG. 3 , reamer shoe  122  has a cutting structure  124  that preferably includes a plurality of inserts  126  such as tungsten carbide inserts, polycrystalline diamond compact inserts or the like. As illustrated, inserts  126  are positioned on the leading edges of a plurality of reaming blades  128  such that inserts  126  will contact not only the bottom of the wellbore or restriction in the wellbore but also the sides of the wellbore during rotation of reamer shoe  122 . Reamer shoe  122  includes a plurality of flow ports that are depicted as nozzles  130 . Even though a particular type of reamer shoe has been depicted and described, those skilled in the art will recognize that other types of reamer shoes having cutting structures that are operable to ream a wellbore when rotated could alternatively be used in conjunction with the present invention. 
     In operation, reamer assembly  100  is coupled to the lower end of a tubular string such as a liner string, a casing string or the like and is run downhole until, for example, reamer shoe  122  contacts debris or a restriction in the wellbore. At this point, the operator can apply weight on reamer shoe  122  via the tubular string. The applied weight creates a compressive force within reamer assembly  100 . The compressive force within reamer assembly  100  causes mandrel  102  to longitudinally move within sleeve  112 , which contracts reamer assembly  100 , as best seen in  FIG. 4 . Due to the pin  116  and groove  110  coupling of sleeve  112  and mandrel  102 , this longitudinal movement of mandrel  102  relative to sleeve  112  causes sleeve  112  to rotate relative to mandrel  102 . As reamer shoe  122  is securably coupled to sleeve  112 , this rotation of sleeve  112  causes reamer shoe  122  to rotate, thereby reaming the wellbore. Preferably, fluid is circulated from the surface through the tubular string and reamer assembly  100  such that the fluid is injected out of reamer shoe  122  via nozzles  130 . The fluid then carries the cutting to the surface by traveling up through the annulus surrounding the tubular string. 
     The process of rotating reamer shoe  122  can be repeated as necessary such that the tubular string may be positioned in the wellbore as desired. Specifically, by slacking off on the weight being applied to reamer shoe  122 , the tensile force generated by spring  132  as well as the downhole force generated by the pressure drop of fluids travel through nozzles  130 , during pumping operations, will urge sleeve  112  to travel longitudinally relative to mandrel  102  and return reamer assembly  100  to the position depicted in  FIG. 2 . Thereafter, repeated cycles of weight on reamer shoe  122  will rotate reamer shoe  122  as required. 
     Referring next to  FIG. 5 , therein is depicted a reamer assembly  200  for use in an apparatus for reaming a wellbore according to the present invention. Reamer assembly  200  includes a mandrel  202  that preferably includes a box end  204  for threadably coupling mandrel  202  with the lower end of a tubular string. As illustrated, mandrel  202  has four spiral grooves  210  forming a plurality of turns around the outer surface of mandrel  202 . Reamer assembly  200  includes a sleeve  212 . In the illustrated embodiment, sleeve  212  is partially positioned around mandrel  202  and is sized such that mandrel  202  can move longitudinally within sleeve  212 . Sleeve  212  has a plurality of openings  214  that are preferably threaded. A pin  216  is securably received within each of the openings  214  such that pins  216  extend into spiral grooves  210  to secure sleeve  212  and mandrel  202  together. Preferably, sleeve  212  has a box end  220  for threadably coupling sleeve  212  with the upper end of a reamer shoe  222  that includes a cutting structure  224  and a plurality of flow ports (not pictured). 
     In operation, reamer assembly  200  is coupled to the lower end of a tubular string and is run downhole until, for example, reamer shoe  222  contacts debris or a restriction in the wellbore. At this point, the operator can apply weight on reamer shoe  222  via the tubular string. The applied weight creates a compressive force within reamer assembly  200 . The compressive force within reamer assembly  200  causes mandrel  202  to longitudinally move within sleeve  212 , which contracts reamer assembly  200 . Due to the pin  216  and groove  210  coupling of sleeve  212  and mandrel  202 , this longitudinal movement of mandrel  202  relative to sleeve  212  causes sleeve  212  and reamer shoe  222  to rotate relative to mandrel  202 , thereby reaming the wellbore. A fluid is circulated from the surface through the tubular string and reamer assembly  200  such that the fluid is injected out of reamer shoe  222  via the nozzles to carry cutting to the surface. The process of rotating reamer shoe  222  can be repeated as necessary by slacking off on the weight being applied to reamer shoe  222  which allows the downhole force generated by the pressure drop of fluids travel through the nozzles to extend sleeve  212  relative to mandrel  202 . 
     Referring next to  FIG. 6 , therein is depicted a reamer assembly  300  for use in an apparatus for reaming a wellbore according to the present invention. Reamer assembly  300  includes a mandrel  302  that preferably includes a box end  304  for threadably coupling mandrel  302  with the lower end of a tubular string. As illustrated, mandrel  302  has four spiral grooves  310  forming a plurality of turns around the outer surface of mandrel  302 . Reamer assembly  300  includes an outer shroud  306  that is securably coupled to or integral with mandrel  302 . Outer shroud  306  includes a shoulder  308 . Reamer assembly  300  also includes a sleeve  312 . In the illustrated embodiment, sleeve  312  is partially positioned around mandrel  302  and is sized such that mandrel  302  can move longitudinally within sleeve  312 . Sleeve  212  has a plurality of openings  314  that are preferably threaded. A pin  316  is securably received within each of the openings  314  such that pins  316  extend into spiral grooves  310  to secure sleeve  312  and mandrel  302  together. Preferably, sleeve  312  has a box end  320  for threadably coupling sleeve  312  with the upper end of a reamer shoe  322  that includes a cutting structure  324  and a plurality of flow ports (not pictured). Sleeve  312  includes a shoulder  318 . A spring  332  is positioned around mandrel  302 , between shoulder  308  and shoulder  318 . Shroud  306  protects spring  332  from damage during installation and operation of reamer assembly  300 . Reamer assembly  300  operates substantially similar to reamer assembly  100  described above. 
     Referring next to  FIG. 7 , therein is depicted a reamer assembly  400  for use in an apparatus for reaming a wellbore according to the present invention. Reamer assembly  400  includes a mandrel  402  that preferably includes a box end  404  for threadably coupling mandrel  402  with the lower end of a tubular string. As illustrated, mandrel  402  has four spiral grooves  410  forming a plurality of turns around the outer surface of mandrel  402 . Mandrel  402  includes a radially expanded section  406  that defines a shoulder  408 . Reamer assembly  400  includes a sleeve  412 . In the illustrated embodiment, sleeve  412  is partially positioned around mandrel  402  and is sized such that mandrel  402  can move longitudinally within sleeve  412 . Sleeve  412  has a plurality of openings  414  that are preferably threaded. A pin  416  is securably received within each of the openings  414  such that pins  416  extend into spiral grooves  410  to secure sleeve  412  and mandrel  402  together. Preferably, sleeve  412  has a box end  420  for threadably coupling sleeve  412  with the upper end of a reamer shoe  422  that includes a cutting structure  424  and a plurality of flow ports (not pictured). Sleeve  412  includes a shoulder  418 . A spring  432  is positioned around mandrel  402 , between shoulder  408  and shoulder  418 . Reamer assembly  400  includes an outer shroud  434  that is securably coupled to or integral with sleeve  412 . Shroud  434  includes one or more slots  436 . Shroud  434  protects spring  432  from damage during installation and operation of reamer assembly  400  and slots  436  allow fluid to flow around spring  432  to keep this area free from debris. Reamer assembly  400  operates substantially similar to reamer assembly  100  described above. 
     Referring next to  FIG. 8 , therein is depicted a reamer assembly  500  for use in an apparatus for reaming a wellbore according to the present invention. Reamer assembly  500  includes a mandrel  502  that preferably includes a box end  504  for threadably coupling mandrel  502  with the lower end of a tubular string. Mandrel  502  includes a radially expanded section  506  that defines a shoulder  508 . As illustrated, mandrel  502  has four spiral grooves  510  forming a plurality of turns around the outer surface of mandrel  502 . Mandrel  502  has one or more slots  536 . Reamer assembly  500  includes a sleeve  512 . In the illustrated embodiment, sleeve  512  is partially positioned around mandrel  502  and is sized such that mandrel  502  can move longitudinally within sleeve  512 . Sleeve  512  has a plurality of openings  514  that are preferably threaded. A pin  516  is securably received within each of the openings  514  such that pins  516  extend into spiral grooves  510  to secure sleeve  512  and mandrel  502  together. Preferably, sleeve  512  has a box end  520  for threadably coupling sleeve  512  with the upper end of a reamer shoe  522  that includes a cutting structure  524  and a plurality of flow ports (not pictured). Sleeve  512  includes a shoulder  518 . A spring  532  is positioned around mandrel  502 , between shoulder  508  and shoulder  518 . Reamer assembly  500  includes an outer shroud  534  that is securably coupled to or integral with sleeve  512 . Shroud  534  protects spring  532  from damage during installation and operation of reamer assembly  500  and slots  536  of mandrel  502  allow fluid to flow around spring  532  to keep this area free from debris. Reamer assembly  500  operates substantially similar to reamer assembly  100  described above. 
     Referring next to  FIG. 9 , therein is depicted a reamer assembly  600  for use in an apparatus for reaming a wellbore according to the present invention. Reamer assembly  600  includes a mandrel  602  that preferably includes a box end  604  for threadably coupling mandrel  602  with the lower end of a tubular string. Mandrel  602  includes a radially expanded section  606  that defines a shoulder  608 . As illustrated, mandrel  602  has a single continuous groove depicted as a J-slot  610  forming a plurality of turns around the outer surface of mandrel  602 . Reamer assembly  600  includes a sleeve  612 . In the illustrated embodiment, sleeve  612  is partially positioned around mandrel  602  and is sized such that mandrel  602  can move longitudinally within sleeve  612 . Sleeve  612  has a plurality of openings  614  that are preferably threaded. A pin  616  is securably received within each of the openings  614  such that pins  616  extend into J-slot  610  to secure sleeve  612  and mandrel  602  together. Preferably, sleeve  612  has a box end  620  for threadably coupling sleeve  612  with the upper end of a reamer shoe  622  that includes a cutting structure  624  and a plurality of flow ports (not pictured). Sleeve  612  includes a shoulder  618 . A spring  632  is positioned around mandrel  602 , between shoulder  608  and shoulder  618 . Reamer assembly  600  operates substantially similar to reamer assembly  100  described above except that sleeve  612  and therefore reamer shoe  622  rotate to the right as reamer assembly  600  is compressed but do not counter rotate on the reverse stroke as pins  616  travel in the longitudinal portions of J-slot  610 . 
     While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.