Patent Application
20100252331
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.
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.
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.
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.”
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.”
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.
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.
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.
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.
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.
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.
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:
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.
An embodiment of a boring shoe 10 of the present invention is shown in
The boring shoe 10 shown in
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.
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.
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.
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.
In additional embodiments, the crown 20 may not include blades 22 and cutting elements 26, like those shown in
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 (
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
Referring again to
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).
The adaptable shank 30 has a wall thickness TW 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 TW may vary, depending upon the size (e.g., the diameter) of the crown 40 to which the shank 30 is attached. The wall thickness TW 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
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 TW 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.
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 TW 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 TW 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 TW 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.
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 TW 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 TW of about 1.263 inches or more (i.e., about 5.3% or more of the diameter of the crown 40).
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.
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.
Referring to
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.
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 38A of the shank 30 may be formed to comprise what is referred to in the art as a “threaded box.”
To form a threaded box in the inner surface 38A of the shank 30, a section of the inner surface 38A of the shank 30 at the second end 31B thereof may be formed to comprise a taper, such that the section of the inner surface 38A has a frustoconical shape have a diameter that is greatest at the opening of the shank 30 at the second end 31B thereof, the diameter becoming progressively smaller moving in the longitudinal direction toward the first end 31A of the shank 30. The angle of the taper of the inner surface 38A of the shank 30 at the second end 31B 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 38A using, for example, conventional machining processes such as turning processes, milling processes, and combinations of turning and milling processes.
Furthermore, threads 37 may be formed on a section of the inner surface 38A of the shank 30 at the second end 31B (e.g., on a tapered section of the inner surface 38A). 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 38A 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.
In some embodiments, threads 37 may be formed on the inner surface 38A of the shank 30 at the second end 31B thereof without providing any taper on the inner surface 38A. In other words, the inner surface 38A may remain at least substantially cylindrical, and a section of the cylindrical inner surface may be threaded.
In additional embodiments of the present invention, an outer surface 38B 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.
Referring to
In the embodiment shown in
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.
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.
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.
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.
