Patent Application
20140262521
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In order to meet consumer and industrial demand for natural resources, companies often invest significant amounts of time and money in finding and extracting oil, natural gas, and other subterranean resources from the earth. Particularly, once a desired subterranean resource such as oil or natural gas is discovered, drilling and production systems are often employed to access and extract the resource. These systems may be located onshore or offshore depending on the location of a desired resource.
Whether onshore or offshore, a drilling rig can be provided to drill a well to access the desired resource. A drill string can be suspended from the drilling rig and rotated to drill the well. While the drill string can be suspended from a kelly and driven by a rotary table on the drill floor of the drilling rig, in some instances the drill string is instead suspended from and driven by a top drive of the drilling rig. Such a top drive generally includes a drive stem (also referred to as a main shaft) that can be connected to the drill string. A motor in the top drive is connected to the drive stem to drive rotation of the drill string via the drive stem. The top drive can be raised and lowered via a hoisting system to raise and lower the drill string within the well.
Certain aspects of some embodiments disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.
Embodiments of the present disclosure generally relate to a top drive having a drive stem with a threaded surface for engaging a threaded load nut. In one embodiment, a top drive includes a load nut and a drive stem that have mating threaded surfaces such that one or more other components of the top drive can be suspended from the drive stem via the load nut. In some instances, a drill string can be suspended from the one or more other components such that the weight of the drill string and the one or more other components cause the load nut to load against the drive stem via the mating threaded surfaces. In at least one embodiment, a portion of one or both of the mating threaded surfaces of the load nut and the drive stem (e.g., one or more thread roots of the drive stem) is shot-peened to increase its load capability. Also, the threadform of one or both of the mating threaded surfaces can include thread roots that are undercut.
Various refinements of the features noted above may exist in relation to various aspects of the present embodiments. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of some embodiments without limitation to the claimed subject matter.
These and other features, aspects, and advantages of certain embodiments will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, any use of “top,” “bottom,” “above,” “below,” other directional terms, and variations of these terms is made for convenience, but does not require any particular orientation of the components.
Turning now to the present figures, a drilling system 10 is illustrated in
The drilling rig 14 also includes a mast 20 and a hoisting system (here generally shown as including a traveling block 22, a crown block 24, and drawworks 26) to enable a top drive 28 to be raised and lowered with respect to a drill floor 30. The drill string 16 is suspended from the top drive 28 through a hole in the drill floor 30 and through surface equipment (e.g., a blowout preventer 32 in the cellar). The drill string 16 can be rotated by the top drive 28 and can be raised and lowered with the top drive 28 (via the traveling block 22) to facilitate drilling operations.
One example of a top drive 28 is generally depicted in
As shown in
A handling ring can include various internal components that enable the weight of the handling ring, the elevator, and the pipe handler, as well as other components connected thereto (such as a drill string), to be supported by a drive stem. In some previous top drives, a handling ring included load collars having multiple, concentric “fingers” provided along the inner bores of the load collars. The fingers of a load collar could interlock with mating grooves on a drive stem to support the weight of the handling ring (and of any equipment suspended from the handling ring, such as a drill string via an elevator or a pipe handler). The load collar could be split into two pieces to facilitate connection of the load collar about the drive stem. In at least some of these previous arrangements, the load collar is retained on the drive stem by a locking hub assembled about the load collar segments with an interference fit. Particularly, the locking hub could be shrink-fitted to the load collar segments by heating the locking hub (causing thermal expansion), installing it on the load collar segments, and then allowing it to cool (resulting in thermal contraction).
But in at least some embodiments of the present technique, the handling ring 48 includes a threaded surface, such as a threaded load nut, rather than a load collar with fingers. One example of such an embodiment is provided in
The load nut 62 includes a threaded surface 64 that allows the load nut 62 to engage a mating threaded surface of the drive stem 46. The connection between these mating threaded surfaces enables the load nut 62 to load against the drive stem 46. A retaining ring 66 is shown as fastened to the load nut 62 and includes a threaded surface 68 that allows the retaining ring 66 to also engage the mating threaded surface of the drive stem 46. Bearings 70 and 72 permit rotation of the load nut 62 and the retaining ring 66 with the drive stem 46. The handling ring 48 also includes a spacer 74 for separating the retaining ring 66 from the bearing 72. The load nut 62, the retaining ring 66, and other components are enclosed within the handling ring 48 by a carrier 76 fastened to the main body 54 and a retaining ring 78 fastened to the carrier 76.
Exploded views of the load nut 62, the retaining ring 66, and a drive stem 86 are provided in
In some embodiments, the number of attachment holes 88 exceeds the number of attachment recesses 90. For example, as depicted in
In some instances, rotating the retaining ring 66 along the threaded surface 94 to tightly engage the load nut 62 can result in the attachment holes 88 of the retaining ring 66 not properly aligning with the attachment recesses 90 of the load nut 62 (e.g., due to manufacturing tolerances). In such instances, the retaining ring 66 may be slightly backed off from the load nut 62 on the threaded surface 94 to align the recesses 90 with the holes 88, or with a subset of the holes 88 if there are a greater number of holes 88 than recesses 90. The inclusion of a greater number of holes 88 than recesses 90 reduces the extent to which the retaining ring 66 would have to be backed off from the load nut 62 to achieve alignment and allow fasteners to be inserted in to the recesses 90 through some of the holes 88.
The mating threaded surfaces 64 and 94 can include any suitable type of threads. For example, these mating threaded surfaces 64 and 94 could include buttress threads in some embodiments. One such embodiment of the threaded surfaces 64 and 94 having buttress threads is generally depicted in
Referring first to
Turning now to the threaded surface 94 of the drive stem 86, the threadform depicted in
When installed in the top drive, the threaded surface 64 of the load nut 62 loads against the threaded surface 94 of the drive stem 86 (e.g., through engagement of the thread flanks 112 and 132). The magnitude of stress on these threaded surfaces generally depends on the weight of components, such as the handling ring 48, the pipe handler 50, the elevator 52, and the drill string 16, suspended from the load nut 62. In some embodiments, the threaded surfaces 64 and 94 are modified for greater strength, durability, and loading capabilities. For instance, at least a portion of one or both of the threaded surfaces 64 and 94 is shot-peened in some embodiments. In one particular embodiment, the only portion of the threaded surfaces 64 and 94 that is shot-peened is a subset of thread roots of the threaded surface 94 (e.g., three thread roots at the top of the threaded surface 94 in
Another modification to increase durability and loading capability of a threaded surface, such as the threaded surface 64 or the threaded surface 94, includes undercutting one or more roots of the threaded surface. Such undercutting may be used in addition to, or instead of the shot peening described above. In one embodiment generally depicted in
While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
