Patent Application
20190040696
In one or more embodiments, the present application discloses an apparatus for maintaining alignment of a rod. More particularly, in one or more embodiments, the present application relates to an apparatus for maintaining the alignment of a reciprocating rod entering and exiting a bore. Still more particularly, the present application relates to an apparatus for maintaining the alignment of a polished rod reciprocating in and out of an oil well, for example, due to the action of a pump jack.
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Downhole reciprocating pumps may be positioned in a wellbore and actuated by a rod string extending from a pump jack at the surface and downward into the wellbore. The rod string may be a continuous member or a plurality of sucker rods connected end-to-end, with a “polished rod” located at its surface-end. The rod may reciprocate in an up/down motion due to action of the pump jack, for example. The reciprocating motion of the rod may drive a piston or other pump mechanism to create pressure and drive fluid upward and out of the well. A stuffing box may be provided at the surface to create a seal around the polished rod. The stuffing box may include a body with seals located therein to create a seal around the moving polished rod passing therethrough in order to retain wellbore fluid pressures and prevent the leakage of wellbore fluids.
It is not uncommon for the polished rod to become misaligned with the axis of the bore of the stuffing box through normal usage, through damage, or through wear or stress on the system. For example, when the overhead pump jack is not perfectly centered over the stuffing box, it may pull the polished rod off-center. Moreover, the action of the pump jack may be along a radius and, as such, may not pull completely parallel to the rod at all times. Still other factors may contribute to misalignment of the rod with the stuffing box, the other mentioned devices, or other systems.
As may be appreciated, a misaligned polished rod can cause excessive and uneven wear to one or more sides of the seals of the stuffing box. This can lead to premature wear, leakage of wellbore fluids, or even damage to the polished rod. That is, for example, if the stuffing box seals wear to the point where the polished rod contacts the metal body of the stuffing box, the polished rod itself may begin to wear or wear more quickly. Damage to the polished rod can quickly cause leaks and could also result in the rod breaking, dropping the sucker rod string downhole, or other drastic and/or dangerous conditions.
Attempts to maintain rod alignment have included the use of rings or bushings spaced within the bore of the stuffing box. These types of bushings may keep the polished rod aligned with the bore of the stuffing box for a period of time, but their soft nature together with the constant reciprocating motion of the polished rod may cause the bushings to wear relatively quickly, leading to the problems stated above. Moreover, replacement of the bushings requires a stoppage of production in order to access the inside of the stuffing box. This can be time consuming because the pump jack may need to be disconnected and the stuffing box disassembled.
The following presents a simplified summary of one or more embodiments of the present disclosure in order to provide a basic understanding of such embodiments. This summary is not an extensive overview of all contemplated embodiments, and is intended to neither identify key or critical elements of all embodiments, nor delineate the scope of any or all embodiments.
In one or more embodiments, an aligning apparatus may include a housing configured for arrangement about a reciprocating rod. The aligning apparatus may also include a bore extending through the housing and having a size configured to allow the reciprocating rod to pass through the bore in a reciprocating and longitudinal motion. The aligning apparatus may also include a plurality of rolling elements arranged along the bore and configured to guide the rod through the bore during reciprocation operations.
In one or more embodiments, a wellhead assembly may include a blowout preventer arranged at the surface of a well and a stuffing box arranged on the blowout preventer for creating a seal around a reciprocating rod entering the well. The wellhead assembly may also include an aligning apparatus with a housing configured for arrangement about the reciprocating rod. The aligning apparatus may also include a bore extending through the housing and having a size configured to allow the reciprocating rod to pass through the bore in a reciprocating and longitudinal motion. The aligning apparatus may also include a plurality of rolling elements arranged along the bore and configured to guide the rod through the bore during reciprocation operations.
In one or more embodiments, a pump jack may include a pivoting beam, a head arranged on the pivoting beam, a reciprocating mechanism configured to pivotally reciprocate the pivoting beam, and a reciprocating rod coupled to the head and extending into a wellbore for powering a pump to pump fluid from the wellbore. The pump jack may also include a stuffing box arranged at the top of the wellbore and having a bore with the reciprocating rod extending therethrough. The pump jack may also include an aligning device arranged at or around the stuffing box with the reciprocating rod extending therethrough and including rolling elements configured to maintain the reciprocating rod in alignment with the bore of the stuffing box.
While multiple embodiments are disclosed, still other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the various embodiments of the present disclosure are capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter that is regarded as forming the various embodiments of the present disclosure, it is believed that the invention will be better understood from the following description taken in conjunction with the accompanying Figures, in which:
The present application, in one or more embodiments, relates to a method and apparatus for maintaining and/or controlling the alignment of a reciprocating, rotating, or otherwise moving rod. In particular, the method and apparatus may include forcing the rod into alignment using a guide or a series of guides arranged on or about the rod. In some particular cases, the reciprocating rod may include a polished rod portion of a pump jack system where the polished rod extends through a stuffing box into a wellbore and the rod reciprocates up and down to drive a well pump. The present apparatus may be provided at or around the stuffing box to force the rod into alignment with the stuffing box to limit, reduce, or avoid prematurely wearing out of the seals on the stuffing box. That is, by maintaining the rod at or near the center of the stuffing box, the rod may not cause as much wear as it would if it was allowed to drift toward the side. If the rod is allowed to drift to the side, it may rub more vigorously on the seals of the stuffing box and cause them to wear prematurely.
Referring now to
Housing 20 can comprise a first housing portion 22 and a second housing portion 24 which can removably couple with each other to form housing 20. For example, and with reference to
Housing 20 may be removably attached to a stuffing box and other wellhead components via any means known in the art such as a threaded engagement, a flange, welding, clamping over a portion of other wellhead components such as a stuffing box, and the like. Additionally or alternatively, the housing may be furnished with a cylindrical protrusion that gets fed through the stuffing cap bore. The housing may then be secured with a U-shaped field-compatible threaded retainer, for example. Still other securing mechanisms may include bolts or a retainer ring (i.e., snap ring).
Mounting means can be shafts/fasteners such as a shoulder bolt upon which the wheel assemblies 50 rotate, or clamp assemblies each comprising an axle upon which a wheel assembly 50 rotates and clamps for securing the axle to the housing 20. In either case, the wheel 54 may be mounted on a shaft 60 that is arranged generally tangentially to and spaced away from the circumference of the rod such that the rotation plane of the wheel is generally perpendicular to the surface of the rod. The shaft 60 may be spaced from the surface of the rod R a distance substantially equal to the radius of the wheel such that the wheel contacts the surface of the rod. As shown in
In an alternate embodiment, as shown in
Wheel assemblies 50 may be mounted in their respective cavities 32 by installing bearing 52 inside wheel 54, inserting axle 100 through bearing 52 and positioning the wheel assembly 50 inside cavity 32 such that the axle 100 rests in the first axle groove 102. The one or more clamps 110 can then be positioned in cavity 32, such that axle 100 is sandwiched between the first axle groove 102 of the cavity 32 and the second axle groove 116 of the one or more clamps 110, and secured to body 20 by inserting clamp fasteners 112 through fastening apertures 120 and threading them into clamp bores 104. As above, if desired, snap rings 53 can be installed on the axle 100 on either side of the wheel 54 to maintain the position of the bearing and the wheel along the axle. The clamp assemblies and wheel assemblies may be accessible from outside the housing and, as such, may allow for removing or replacing the wheel assemblies while the aligning device remains in place.
In one or more embodiments, the above described clamp assemblies may be adjustable assemblies that may function to move the wheel assemblies inward and outward relative the housing and, as such, accommodate different size polished rods. In this embodiment, a clamp fastener may function to secure the axle to an inner plate or stop and a separate adjustment screw may be provided to adjust the position of the inner plate or stop to allow the wheel assembly to move inwardly or outwardly.
The rod aligning apparatus 10 can be installed on a stuffing box or other wellhead component by positioning the first or second housing portion 22,24 such that polished rod R resides within bore 30, and securing the other of the first or second housing portion 22,24 thereto by aligning the first and second coupling bores 25,26 and fastening coupling fasteners 28 through each of the coupling bores 24,25 to secure first and second portions 22,24 to each other. As such, the aligning device may be installed without interruption or disassembly of the reciprocating rod system. In embodiments with a one-piece housing 20, the housing 20 can be slid onto a polished rod R while the pump jack is disconnected from the rod R such that the rod resides within bore 30. The wheel assemblies 50 can then be installed and secured in their respective cavities 32 in the manner described above. Alternatively or additionally, the wheel assemblies may be pre-installed. The apparatus 10 can be secured to the stuffing box in any manner known in the art, such as by coupling the apparatus 10 to a corresponding threaded or flanged engagement of the stuffing box. In the case of an apparatus 10 with multiple housing portions, the housing portions can be clamped over a corresponding portion of the stuffing box before being coupled together. It is to be appreciated that the installation of the alignment apparatus may be performed in the field with new equipment, in the field as a field retrofit of existing equipment, or it may be secured to or installed in a shop setting, for example, by securing it to a stuffing box or other equipment forming other portions of the wellhead.
While a single aligning apparatus has been described, multiple aligning apparatuses may be provided along the length of the rod to address various issues associated with rod deviation. In one or more embodiments, a second or additional aligning apparatus may be provided directly above the apparatus on the stuffing box. In one or more other embodiments, an additional aligning apparatus may be provided above the apparatus on the stuffing box, but spaced apart from it in an upward direction along the rod. In one or more other embodiments, the aligning apparatus or additional aligning apparatuses may be positioned within the wellhead such as below the stuffing box or between the stuffing box and the blowout preventer. Still other numbers and arrangements of aligning apparatuses may be provided. Still further, in one or more embodiments, mechanisms that may provide for dynamic adjustability of the stuffing box may be provided. These devices may allow the stuffing box location, position, or orientation to be adjustable or moveable to accommodate drift in the position of the polished rod. The present aligning apparatus may be provided in addition and in conjunction with such devices.
In use, rod R reciprocates inside the bore 30 of aligning apparatus 10. Wheels 54 maintain the rod R in alignment with the bore of the stuffing box. As the rod R reciprocates, wheels 54 rotate to reduce frictional wear of the rod R thereon. In the event that bearings 52 seize, wheels 54 continue to maintain rod R in alignment by acting as bushings. If the pump jack is not centered over the wellhead stack, or other conditions cause rod R to be misaligned, rod R may tend to exert more wear on to one of the wheels 54 compared to the others. In this situation, for embodiments with multiple housing portions, aligning apparatus 10 can be rotated about rod R by loosening coupling fasteners 28 sufficiently to allow apparatus 10 to be rotated. Apparatus 10 can then be rotated such that rod R will wear on another wheel 54, for example by rotating the aligning apparatus 120 degrees clockwise or counterclockwise. The range or degree of rotation may be any selected degree and while 120 degrees may be suitable for a system of three wheel assemblies, other degrees may be selected based on the number of wheel assemblies and the desired rotation for exposing a less worn wheel assembly to a higher wear condition and removing a highly worn wheel from the higher wear condition. In embodiments with threaded or flanged connections with the stuffing box, the housing 20 can be rotated by tightening or loosening the threaded engagement until the desired degree of rotation is achieved, or by removing the flange bolts, rotating the housing 20, and reinstalling the flange bolts.
When replacement of a wheel 54 and/or bearing 52 is required, the wheel assembly 50 can easily be removed from the housing 20 without removing the apparatus 10 from the wellhead. For example, in embodiments with a fastener 60 mounting means, the fastener 60 of the respective wheel assembly 50 can be loosened and removed to allow the wheel assembly 50 to be removed from its respective cavity 32. In embodiments incorporating a clamp assembly, clamp fasteners 112 and clamp 110 can be removed to free the wheel assembly 50 and axle 100. A new wheel 54 and/or bearing 52 can then be provided to replace the worn wheel 54 and/or bearing 52, and the wheel assembly 50 can be re-secured to the housing 20 in the manner described above.
While the aligning device has been shown for use with a pump jack system such as that shown in
It is to be appreciated that while the aligning apparatus 10 has been described as including wheels or wheel assemblies around the circumference of the polished rod R, other aligning mechanisms may also be provided. For example, a static, low friction element, may be provided rather than a mechanical rolling element, for example. In one or more embodiments, a low friction bushing or series of surrounding bumpers may be provided within the housing of the aligning device. For example, rather than wheel assemblies, a similarly structured assembly may be provided with a supporting axle, but in lieu of a wheel, a low friction slide or bumper may be provided. The low friction bumper assembly may have the advantage over donut shaped bushings in that one or more bumpers may be replaced similar to the wheels and, as such, maintenance may be performed without disassembly of the system. In another example, other rotating or rolling elements may be provided other than isolate wheels or wheel assemblies. For example, one or more linear bearings may be arranged on an inner surface of the housing along the bore for guiding the polished rod. In one or more embodiments, a customized cage with a series of ball bearings arranged in the cage may also be used. In still other embodiments, wheels or rollers may be used. In one or more embodiments, the rollers may be cylindrical, spherical, or conical, for example. In still other embodiments, needle bearings could also be used. Still other types of rotating or rolling elements may be used.
The rolling or rotating elements (including the above-described wheels or the series of rotating or rolling elements introduced here) may include one or more materials selected from metals, coated materials, Teflon, plastic, other materials, or a combination of materials. In one or more embodiments, the material selected may include a hardness that is less than that of the polished rod to avoid marring, scratching, or otherwise wearing on the polished rod. In one or more embodiments, the wheels or the surface of the wheels may include bronze or other relatively soft metals.
As used herein, the terms “substantially” or “generally” refer to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is “substantially” or “generally” enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking, the nearness of completion will be so as to have generally the same overall result as if absolute and total completion were obtained. The use of “substantially” or “generally” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result. For example, an element, combination, embodiment, or composition that is “substantially free of” or “generally free of” an element may still actually contain such element as long as there is generally no significant effect thereof.
In the foregoing description various embodiments of the present disclosure have been presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The various embodiments were chosen and described to provide the best illustration of the principals of the disclosure and their practical application, and to enable one of ordinary skill in the art to utilize the various embodiments with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present disclosure as determined by the appended claims when interpreted in accordance with the breadth they are fairly, legally, and equitably entitled.
The present application claims priority to U.S. Provisional Application No. 62/511,452, filed on May 26, 2017, entitled Method and Apparatus for Rod Alignment, the content of which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62511452 | May 2017 | US |
