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TECHNICAL FIELD 
       [0001]    The present invention relates to earth-boring shoes configured for attachment to a section of wellbore casing, to methods of manufacturing such earth-boring shoes, and to methods of adapting such earth-boring shoes for attachment to a section of wellbore casing. 
       BACKGROUND 
       [0002]    The drilling of wells for oil and gas production conventionally employs longitudinally extending sections or so-called “strings” of drill pipe to which, at one end, is secured a drill bit of a larger diameter. After a selected portion of the borehole has been drilled, the borehole is usually lined or cased with a string or section of casing. Such a casing or liner usually exhibits a larger diameter than the drill pipe and a smaller diameter than the drill bit. Therefore, drilling and casing according to the conventional process typically requires sequentially drilling the borehole using drill string with a drill bit attached thereto, removing the drill string and drill bit from the borehole, and disposing casing into the borehole. Further, often after a section of the borehole is lined with casing, which is usually cemented into place, additional drilling beyond the end of the casing may be desired. 
         [0003]    Unfortunately, sequential drilling and casing may be time consuming because, as may be appreciated, at the considerable depths reached during oil and gas production, the time required to implement complex retrieval procedures to recover the drill string may be considerable. Thus, such operations may be costly as well, since, for example, the beginning of profitable production can be greatly delayed. Moreover, control of the well may be difficult during the period of time that the drill pipe is being removed and the casing is being disposed into the borehole. 
         [0004]    Some approaches have been developed to address the difficulties associated with conventional drilling and casing operations. Of initial interest is an apparatus which is known as a reamer shoe that has been used in conventional drilling operations. Reamer shoes have become available relatively recently and are devices that are able to drill through modest obstructions within a borehole that has been previously drilled. In addition, the reamer shoe may include an inner section manufactured from a material which is drillable by rotary drill bits. Accordingly, when cemented into place, reamer shoes usually pose no difficulty to a subsequent drill bit. For instance, U.S. Pat. No. 6,062,326 to Strong et al. discloses a casing shoe or reamer shoe in which the central portion thereof may be configured to be drilled through. In addition, U.S. Pat. No. 6,062,326 to Strong et al. discloses a casing shoe that may include diamond cutters over the entire face thereof, if it is not desired to drill therethrough. Such reamers that are configured for attachment to a casing string are referred to hereinafter as “reamer shoes.” 
         [0005]    As a further extension of the reamer shoe concept, in order to address the problems with sequential drilling and casing, drilling with casing is gaining popularity as a method for initially drilling a borehole, wherein the casing is used as the drilling conduit and, after drilling, the casing is cemented into and remains within the wellbore to act as the wellbore casing. Drilling with casing employs a drill bit that is configured for attachment to the casing string instead of a drill string, so that the drill bit functions not only to drill the earth formation, but also to guide the casing into the wellbore. This may be advantageous as the casing is disposed into the borehole as it is formed by the drill bit, and therefore eliminates the necessity of retrieving the drill string and drill bit after reaching a target depth where cementing is desired. Such drill bits that are configured for attachment to a casing string are referred to hereinafter as “drill shoes.” 
         [0006]    As used herein, the terms “earth-boring shoes” and “boring shoes” mean and include any device that is configured for attachment to an end of a section of casing and used for at least one of drilling a wellbore, reaming a previously drilled wellbore, and guiding casing through a previously drilled wellbore, as the section of casing to which the device is attached is advanced into a subterranean formation. Earth-boring shoes and boring shoes include, for example, drill shoes, reamer shoes, casing shoes configured to merely guide casing through a wellbore and ensure that the wellbore diameter remains as drilled (i.e., has not decreased as sometimes occurs in reactive or sloughing formations), and shoes that both drill and ream as casing to which they are attached is advanced into a subterranean formation. 
         [0007]    Commercially available casing sections are sold in a variety of different diameters and with a variety of different coupling configurations. As a result, when an earth-boring shoe is manufactured for a particular customer, a conventional boring shoe must be manufactured for the particular diameter of casing to which the boring shoe is to be attached. Furthermore, the boring shoe must be provided with a connection portion that is configured (e.g., with threads) to complimentarily engage the particular connection portion of the casing string to which the boring shoe is to be attached. 
         [0008]    There is a need in the art for improved methods of coupling boring shoes to casing strings, and for improved methods of adapting boring shoes for attachment to casing strings having different connection configurations. 
       BRIEF SUMMARY 
       [0009]    In some embodiments, the present invention includes methods of attaching a crown of a boring shoe to a section of casing. A first end of an adaptable shank may be attached to the crown of a boring shoe, and an opposite, second end of the adaptable shank may be machined to configure the second end of the adaptable shank for attachment to a section of casing after attaching the first end of the adaptable shank to the crown. 
         [0010]    In additional embodiments, the present invention includes methods of attaching boring shoes to sections of casing. A first end of an adaptable shank is welded to a crown to form a boring shoe. The adaptable shank is selected to have an average wall thickness greater than about five percent (5%) of a maximum diameter of the crown. An opposite, second end of the adaptable shank is configured for attachment to a particular type of casing section after welding the first end of the adaptable shank to the crown. 
         [0011]    Yet further embodiments of the present invention include boring shoes having an adaptable shank attached to a crown, wherein the adaptable shank comprises a generally cylindrical wall having an average wall thickness greater than about five percent (5%) of a maximum diameter of the crown. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0012]    While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the present invention, the advantages of embodiments of this invention may be more readily ascertained from the following description of certain embodiments of the invention when read in conjunction with the accompanying drawings, in which: 
           [0013]      FIG. 1  is a perspective view of an embodiment of a shoe tool of the present invention that includes a crown attached to an adaptable shank; 
           [0014]      FIG. 2  is a schematic illustration showing the shoe tool of  FIG. 1  attached to a section of casing and disposed within a subterranean formation; 
           [0015]      FIG. 3  is a longitudinal cross-sectional view of an embodiment of a shoe tool like that of  FIG. 1  including a crown attached to an adaptable shank; 
           [0016]      FIG. 4  is an enlarged cross-sectional view of an interface between the crown and the adaptable shank shown in  FIG. 3 ; 
           [0017]      FIG. 5  is a longitudinal cross-sectional view of the shoe tool shown in  FIGS. 3 and 4  after adapting the shank for connection to casing in accordance with embodiments of methods of the present invention; and 
           [0018]      FIG. 6  is a longitudinal cross-sectional view of the shoe tool shown in  FIG. 5 , further illustrating a section of casing coupled to the shank of the shoe tool. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Illustrations presented herein are not meant to be actual views of any particular device or system, but are merely idealized representations which are employed to describe embodiments of the present invention. Additionally, elements common between figures may retain the same numerical designation. 
         [0020]    An embodiment of a boring shoe  10  of the present invention is shown in  FIG. 1 . The boring shoe  10  shown in  FIG. 1  is an intermediate structure that has not yet been adapted for attachment to any particular section of casing. After formation of the intermediate boring shoe  10  shown in  FIG. 1 , the boring shoe  10  may be adapted for attachment to a particular section of casing, as described in further detail herein below. 
         [0021]    The boring shoe  10  shown in  FIG. 1  may be a reamer shoe or a drill shoe configured for attachment to a section of casing for use in forming a wellbore in a subterranean formation. As shown in  FIG. 1 , the boring shoe  10  includes a crown  20  and an adaptable shank  30  that is attached to the crown  20 . 
         [0022]    In some embodiments, the crown  20  may be configured to drill a wellbore in a subterranean formation. In other embodiments, the crown  20  may be configured to ream (i.e., enlarge the diameter of) a previously drilled wellbore. In yet other embodiments, the crown  20  may be configured to merely guide casing through a wellbore and ensure that the wellbore diameter remains as previously drilled and has not decreased as sometimes occurs in reactive or sloughing formations. In other words, the crown  20  may only ream sections of the wellbore that have an undersized diameter due, for example, to encroachment of the formation material into the wellbore. 
         [0023]    The crown  20  includes a body  21  that may be formed of and comprise, for example, a metal or metal alloy (e.g., steel, aluminum, brass, or bronze), or a composite material including particles of a relatively harder material (e.g., tungsten carbide) embedded within a relatively softer metal or metal alloy (e.g., steel, aluminum, brass, or bronze). The material of the body  21  may be selected to exhibit physical properties that allow the body  21  to be drilled through by another drill bit after the boring shoe  10  has been used to advance a section of casing attached thereto into a subterranean formation, as known in the art. 
         [0024]    Drilling and/or reaming structures may be provided on exterior surfaces of the body  21  of the crown  20 . For example, the crown  20  may comprise a plurality of blades  22  that define fluid courses  24  therebetween. Apertures  25  may be formed through the crown  20  for allowing fluid (e.g., drilling fluid and/or cement) to be pumped through the interior of the boring shoe  10 , out through the apertures  25  in the crown  20 , and into the annular space between the walls of the formation in which the wellbore is formed and the exterior surfaces of the boring shoe  10  and the casing sections to which the boring shoe  10  may be attached. For example, the apertures  25  may comprise fluid passageways extending through the body  21  of the crown  20 . Optionally, nozzles (not shown) may be secured to the crown  20  within the fluid passageways to selectively tailor the hydraulic characteristics of the boring shoe  10 . Cutting element pockets may be formed in the blades  22 , and cutting elements  26 , such as, for example, polycrystalline diamond compact (PDC) cutting elements, may be secured within the cutting element pockets. 
         [0025]    Also, each of blades  22  may include a gage region  23  that together define the largest diameter of the crown  20  and, thus, the diameter of any wellbore formed using the crown  20  and boring shoe  10 . The gage regions  23  may be longitudinal extensions of the blades  22 . Wear-resistant structures or materials may be provided on the gage regions  23 . For example, tungsten carbide inserts, cutting elements, diamonds (e.g., natural or synthetic diamonds), or hardfacing material may be provided on the gage regions  23  of the crown  20 . 
         [0026]    In additional embodiments, the crown  20  may not include blades  22  and cutting elements  26 , like those shown in  FIG. 1 . In such embodiments, the crown  20  may comprise other cutting and/or reaming structures such as, for example, deposits of hardfacing material (not shown) on the exterior surfaces of the crown  20 . Such a hardfacing material may comprise, for example, hard and abrasive particles (e.g., diamond, boron nitride, silicon carbide, carbides or borides of titanium, tungsten, or tantalum, etc.) embedded within a metal or metal alloy matrix material (e.g., an iron-based, cobalt-based, or nickel-based metal alloy). Such deposits of hardfacing material may be shaped into elongated, protruding structures on the exterior surfaces of the crown  20 . 
         [0027]      FIG. 2  is a simplified schematic illustration showing the boring shoe  10  attached to a section of casing  39  and disposed within a wellbore that has been formed in a subterranean formation using the boring shoe  10 . As previously discussed, the casing  39 , with the boring shoe  10  attached thereto, may be rotated and advanced into the subterranean formation as drilling fluid is pumped down through the interior of the casing  39 , out through the apertures  25  in the crown  20 , and up through the fluid courses  24  ( FIG. 1 ) and up through the annular space between the walls of the formation within the wellbore and the exterior surfaces of the casing  39  to the surface of the formation. 
         [0028]    Once the casing  39  has been advanced to a desirable location within the formation, drilling with the boring shoe  10  may be ceased, and the casing  39  may be cemented in place. To cement the casing  39  in place, cement (not shown) or another curable material may be forced through the interior of casing  39 , through the apertures  25  in the crown  20 , up through the fluid courses  24  ( FIG. 1 ), and into the annulus between the wall of wellbore and the outer surface of the casing  39 , where it may be allowed to harden. Of course, conventional float equipment may be used for controlling and delivering the cement through the boring shoe  10  and into the annulus between the wall of the wellbore and the casing  39 . Cementing the casing  39  in place within the wellbore may stabilize the wellbore and seal the subterranean formations penetrated by the boring shoe  10  and the casing  39 . 
         [0029]    In some instances, the size and placement of the apertures  25  that are employed for drilling operations may not be particularly desired for cementing operations. Furthermore, the apertures  25  may become plugged or otherwise obstructed during a drilling operation. As shown in  FIGS. 1 and 2 , at least one of the crown  20  and the shank  30  of the boring shoe  10  may include one or more frangible regions  28  that can be breached (e.g. a metal disc that can be fractured, perforated, ruptured, removed, etc.) to form one or more additional apertures that may be used to provide fluid communication between the interior and the exterior of the boring shoe  10 . Drilling fluid and/or cement optionally may be caused to flow through such frangible regions  28  after breaching the same. 
         [0030]    Referring again to  FIG. 1 , the boring shoe  10  includes an adaptable shank  30  having a first end  31 A attached to the crown  20  and a second end  31 B that may be adapted and used to couple the boring shoe  10  to a section of casing (not shown in  FIG. 1 ). The shank  30  may have a size and shape that allows it to be adapted, after attachment to the crown  20 , for coupling to a wide variety of different casing configurations, as discussed in further detail herein below. 
         [0031]      FIG. 3  is a longitudinal, cross-sectional view of another embodiment of an intermediate boring shoe  50  of the present invention. The intermediate boring shoe  50  is similar to the boring shoe  10  shown in  FIG. 1 , and includes a crown  40  having a body  41  that is attached to an adaptable shank  30 , as previously described in relation to  FIG. 1 . 
         [0032]    The adaptable shank  30  is a cylindrical structure having a length L. By way of example and not limitation, the length L of the adaptable shank  30  may be between about twenty-five (25) centimeters (about ten (10) inches) and about two hundred (200) centimeters (about seventy-nine (79) inches). 
         [0033]    The adaptable shank  30  has a wall thickness T W  that is one-half of the difference between the outer diameter OD of the shank  30  and the inner diameter ID of the shank  30 . The wall thickness T W  may vary, depending upon the size (e.g., the diameter) of the crown  40  to which the shank  30  is attached. The wall thickness T W  of the shank  30 , however, may be sufficiently large to allow the shank  30  to be adapted for use with a number of different casing sections having a variety of weights and coupling configurations that might be used with the particular size of crown  40  to which the shank  30  is attached. Although the shank  30  of  FIG. 3  is shown having an outer diameter that is less than an outer diameter of the crown  40  to which the shank  30  is attached, in additional embodiments, the shank  30  may have an outer diameter that is larger than a diameter of the crown  40  to which the shank  30  is attached. 
         [0034]    Table 1 below lists a variety of different diameters of crowns that are often used in the industry, together with the outer diameter OD, the inner diameter ID, and the wall thickness T W  of examples of adaptable shanks  30  of the present invention that may be attached to such crowns. All dimensions in Table 1 are given in inches, and dimensions in centimeters are provided in parenthesis. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Shank T W  as 
               
               
                 Crown 
                 Casing 
                   
                   
                   
                 Percentage of 
               
               
                 Diameter 
                 Diameter 
                 Shank OD 
                 Shank ID 
                 Shank T W   
                 Crown Diameter 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 6.00 
                 in 
                 4.50 
                 in 
                 5.125 
                 in 
                 3.625 
                 in 
                 0.750 
                 in 
                 12.5% 
               
               
                 (15.24 
                 cm) 
                 (11.43 
                 cm) 
                 (13.02 
                 cm) 
                 (9.21 
                 cm) 
                 (1.91 
                 cm) 
               
               
                 8.50 
                 in 
                 7.625 
                 in 
                 8.625 
                 in 
                 6.00 
                 in 
                 1.313 
                 in 
                 15.4% 
               
               
                 (21.59 
                 cm) 
                 (19.37 
                 cm) 
                 (21.91 
                 cm) 
                 (15.24 
                 cm) 
                 (3.34 
                 cm) 
               
               
                 12.25 
                 in 
                 9.625 
                 in 
                 10.750 
                 in 
                 8.310 
                 in 
                 1.220 
                 in 
                 10.0% 
               
               
                 (31.12 
                 cm) 
                 (24.45 
                 cm) 
                 (27.31 
                 cm) 
                 (21.11 
                 cm) 
                 (3.10 
                 cm) 
               
               
                 17.50 
                 in 
                 13.375 
                 in 
                 14.500 
                 in 
                 12.250 
                 in 
                 1.125 
                 in 
                 6.4% 
               
               
                 (44.45 
                 cm) 
                 (33.97 
                 cm) 
                 (36.83 
                 cm) 
                 (31.12 
                 cm) 
                 (2.86 
                 cm) 
               
               
                 24.00 
                 in 
                 20.00 
                 in 
                 21.125 
                 in 
                 18.60 
                 in 
                 1.263 
                 in 
                 5.3% 
               
               
                 (60.96 
                 cm) 
                 (50.80 
                 cm) 
                 (53.66 
                 cm) 
                 (47.24 
                 cm) 
                 (3.21 
                 cm) 
               
               
                   
               
             
          
         
       
     
         [0035]    As shown in Table 1, in some embodiments of the present invention, the crown  40  may have a diameter that is about 12.25 inches or less, and the adaptable shank  30  may have a wall thickness that is about 10% or more of the diameter of the crown  40 , about 12% or more of the diameter of the crown  40 , or even about 15% or more of the diameter of the crown  40 . As one particular non-limiting example, the crown  40  may have a diameter of about 12.25 inches, the shank  30  may have an outer diameter OD of about 10.750 inches, an inner diameter ID of about 8.310 inches or less, and a wall thickness T W  of about 1.220 inches or more (i.e., about 10.0% or more of the diameter of the crown  40 ). As another particular non-limiting example, the crown  40  may have a diameter of about 8.50 inches, the shank  30  may have an outer diameter OD of about 8.625 inches, an inner diameter ID of about 6.00 inches or less, and a wall thickness T W  of about 1.313 inches or more (i.e., about 15.4% or more of the diameter of the crown  40 ). As yet another particular non-limiting example, the crown  40  may have a diameter of about 6.00 inches, the shank  30  may have an outer diameter OD of about 5.125 inches, an inner diameter ID of about 3.625 inches or less, and a wall thickness T W  of about 0.750 inches or more (i.e., about 12.5% or more of the diameter of the crown  40 ). Other non-limiting examples of embodiments of the invention are also set forth in Table 1 above. 
         [0036]    As shown in Table 1, in additional embodiments of the present invention, the crown  40  may have a diameter that is greater than about 12.25 inches, and the adaptable shank  30  may have a wall thickness that is about 5% or more of the diameter of the crown  40 , or even about 6% or more of the diameter of the crown  40 . As one particular non-limiting example, the crown  40  may have a diameter of about 17.50 inches, the shank  30  may have an outer diameter OD of about 14.500 inches, an inner diameter ID of about 12.250 inches or less, and a wall thickness T W  of about 1.125 inches or more (i.e., about 6.4% or more of the diameter of the crown  40 ). As another particular non-limiting example, the crown  40  may have a diameter of about 24.00 inches, the shank  30  may have an outer diameter OD of about 21.125 inches, an inner diameter ID of about 18.60 inches or less, and a wall thickness T W  of about 1.263 inches or more (i.e., about 5.3% or more of the diameter of the crown  40 ). 
         [0037]    The adaptable shank  30  may be formed from and comprise a metal material such as, for example, an iron-based metal alloy (e.g., a steel alloy). In some embodiments, the adaptable shank  30  may be formed from and comprise a material that exhibits a tensile yield strength of at least about 60,000 pounds per square inch (PSI), at least about 90,000 pounds per square inch (PSI), or even at least about 120,000 PSI pounds per square inch (PSI). As previously mentioned, the adaptable shank  30  may be separately formed from the crown  40  and subsequently attached thereto. 
         [0038]      FIG. 4  is an enlarged cross-sectional view of an interface between the crown  40  and the adaptable shank  30  shown in  FIG. 3 . As shown in  FIG. 4 , the shank  30  may be attached to the crown  40  by abutting an end surface  34  of the shank  30  against an end surface  48  of the crown  40  and welding an interface between the shank  30  and the crown  40 . In other words, a weld material  60  (e.g., one or more weld beads) may be provided around an exterior surface of the intermediate boring shoe  50  along the interface between the crown  40  and the shank  30 . In some embodiments, the shank  30  may have a beveled, frustoconical surface  36  at the first longitudinal end  31 A thereof, and the crown  40  may have a complementary beveled, frustoconical surface  49 . The frustoconical surface  36  of the shank  30  and the frustoconical surface  49  of the crown  40  may define a weld groove therebetween when the shank  30  is abutted against the crown  40 . A weld material  60  may be deposited in the form of one or more weld beads within the weld groove to weld the shank  30  and the crown  40  together. The shank  30  may be abutted against, and welded to, the crown  40  prior to adapting the shank  30  for attachment to a section of casing. 
         [0039]    In additional embodiments, complementary threads (not shown) may be provided on the crown  40  and the shank  30  to allow the crown  40  and the shank  30  to be threaded together to attach the crown  40  and the shank  30  together. In such embodiments, a weld material  60  also may be provided along the interface between the crown  40  and the shank  30  to further secure the crown  40  and the shank  30  together. 
         [0040]    Referring to  FIG. 5 , after attaching the shank  30  and the crown  40  together, the shank  30  may be adapted for attachment to a particular section of casing. The shank  30  may be adapted for attachment to a particular section of casing by, for example, doing one or more of the following: reducing the length L of the shank  30 , reducing the wall thickness T W  of the shank  30 , and providing one or more features on the shank  30 , and/or shaping one or more surfaces of the shank  30 , for coupling to an end of a section of casing. The wall thickness T W  of the shank  30  may be reduced by reducing the outer diameter of the shank  30 , by increasing the inner diameter of the shank  30 , or by both reducing the outer diameter and increasing the inner diameter of the shank  30 . 
         [0041]    The outer diameter of the shank  30  may be reduced, and the inner diameter of the shank  30  may be increased, as desirable, using, for example, conventional machining processes such as turning processes, milling processes, and combinations of turning and milling processes. 
         [0042]    To configure the shank  30  for coupling to a section of casing, one or more features may be provided on the shank  30 , and/or one or more surfaces of the shank  30  may be provided with a certain shape, as previously mentioned. For example, an inner surface  38 A of the shank  30  may be formed to comprise what is referred to in the art as a “threaded box.” 
         [0043]    To form a threaded box in the inner surface  38 A of the shank  30 , a section of the inner surface  38 A of the shank  30  at the second end  31 B thereof may be formed to comprise a taper, such that the section of the inner surface  38 A has a frustoconical shape have a diameter that is greatest at the opening of the shank  30  at the second end  31 B thereof, the diameter becoming progressively smaller moving in the longitudinal direction toward the first end  31 A of the shank  30 . The angle of the taper of the inner surface  38 A of the shank  30  at the second end  31 B may be selected to correspond to the angle of a taper on the exterior surface of a section of casing to which the shank  30  is to be attached. Such a taper also may be formed in the inner surface  38 A using, for example, conventional machining processes such as turning processes, milling processes, and combinations of turning and milling processes. 
         [0044]    Furthermore, threads  37  may be formed on a section of the inner surface  38 A of the shank  30  at the second end  31 B (e.g., on a tapered section of the inner surface  38 A). The size (e.g., dimensions), shape, and spacing (e.g., pitch) of the threads  37  also may be selected to correspond to the size (e.g., dimensions), shape, and spacing (e.g., pitch) of complementary threads on a section of casing to which the shank  30  is to be attached. The threads  37  also may be formed in the inner surface  38 A using, for example, conventional machining processes such as turning processes, milling processes, and combinations of turning and milling processes. Threads may also be formed by rolling the surface to be threaded against a threading die, as known in the art, and such roll threading processes also may be employed in embodiments of the present invention. 
         [0045]    In some embodiments, threads  37  may be formed on the inner surface  38 A of the shank  30  at the second end  31 B thereof without providing any taper on the inner surface  38 A. In other words, the inner surface  38 A may remain at least substantially cylindrical, and a section of the cylindrical inner surface may be threaded. 
         [0046]    In additional embodiments of the present invention, an outer surface  38 B of the shank  30  may be formed to comprise what is referred to in the art as a “threaded pin,” which is a male pin member having threads on an exterior surface thereof that is configured to mate with, and engage, a female threaded box, as previously described herein. 
         [0047]    Referring to  FIG. 6 , after adapting the shank  30  for attachment to a particular section of casing  61 , the shank  30  and the section of casing  61  may be coupled together in preparation for drilling and/or reaming with the boring shoe  50  as the casing  61  and the boring shoe  50  are advanced into a subterranean formation. 
         [0048]    In the embodiment shown in  FIG. 6 , a threaded box is provided on the inner surface  38 A of the shank  30  at the second end  31 B thereof, and the section of casing  61  has a threaded pin  62  at an end  64  thereof that is complementary to, and configured to mate with and engage, the threaded box at the second end  31 B of the shank  30 . 
         [0049]    In additional embodiments of the invention, however, the shank  30  may be formed to comprise a threaded pin, and the casing  61  may comprise a complementary threaded box configured to engage the threaded pin of the shank  30 . In yet further embodiments, each of the shank  30  and the casing  61  may comprise a threaded pin, and a collar having a threaded box on both ends thereof may be used to couple the threaded pin of the shank  30  to the threaded pin of the casing  61 . Such collars are commercially available and frequently used in the art. 
         [0050]    Thus, in accordance with some embodiments of methods of the present invention, an adaptable shank may be attached to a crown of a boring shoe prior to identifying the type of casing to which the boring shoe will ultimately be attached. As a result, a manufacturer need not fabricate a variety of different types of shanks for each size of boring shoe, each type corresponding to the different types of casing to which the boring shoe might be attached. In contrast, a single, adaptable shank in accordance with embodiments of the present invention may be fabricated for each size of boring shoe, and the adaptable shank can be adapted, after attachment to a crown, for attachment to a particular type of casing. 
         [0051]    Furthermore, in accordance with some embodiments of methods of the present invention, an adaptable shank may be attached to a crown of a boring shoe prior to identifying the type of casing to which the boring shoe will ultimately be attached. The crown, with the adaptable shank attached thereto, may be transported to another location other than where the crown and shank were attached together (e.g., the location of a distributor, the location of a drilling site, etc.) by way of a vehicle (e.g., a truck, plane, or boat). After transporting the crown, with the adaptable shank attached thereto, to another location, a particular type of casing to which the crown and adaptable shank are to be attached may be identified, and the adaptable shank may be adapted, as previously described herein, for attachment to that particular type of casing. 
         [0052]    While the present invention has been described herein with respect to certain embodiments, those of ordinary skill in the art will recognize and appreciate that it is not so limited. Rather, many additions, deletions and modifications to the embodiments described herein may be made without departing from the scope of the invention as hereinafter claimed. In addition, features from one embodiment may be combined with features of another embodiment while still being encompassed within the scope of the invention as contemplated by the inventors.

Summary:
Methods of attaching a crown of a boring shoe to a casing section include attaching an adaptable shank to a crown, and machining the adaptable shank to configure an end thereof for attachment to a casing section after attaching the adaptable shank to the crown. Additional methods include welding an end of an adaptable shank to a crown to form a boring shoe, selecting the adaptable shank to have an average wall thickness greater than about five percent (5%) of a maximum diameter of the crown, and configuring an opposite end of the adaptable shank for attachment to a particular type of casing section after welding the shank to the crown. Boring shoes have an adaptable shank attached to a crown, wherein the shank comprises a generally cylindrical wall having an average wall thickness greater than about five percent (5%) of a maximum diameter of the crown.