Patent Grant
11976521
The present application is generally related to centralizers and more particularly to a centralizer for use within a long-spanning, cylindrical tube or pipe in high speed rotor dynamics applications.
A rod centralizer or a drive shaft centralizer is often used to keep a rotating rod (or a rod string) centered in a tubing string and functions to prevent the rotating rod from contacting the inner surface of the tubing. In some applications, a rod may need to be rotated at a relatively high rate. In general, the conventional commercially available rod or drive shaft centralizer technology (i.e., spin-through technology) is not suitable for use in high speed rotary applications. Conventional rod or drive shaft centralizers are generally not designed to handle the high speed rod/shaft rotations and resulting rotor dynamic loadings.
Some existing centralizers that are used with a rotating rod may include solid vanes, ribs or other rigid features that abut against the inner surface of a tubing to keep the rod centered. However, such rigid structures cannot assure that the centralizer is held fixed to the tubing (i.e. rotationally static). A centralizer that has solid vanes may rotate relative to the tubing after insertion into the tubing because an interference fit cannot be guaranteed due to wear during the insertion. Further, the overall outer diameter of centralizer vanes that may be required to provide a desired rigidity and/or fixity may prevent the rod from reaching desired depths because the centralizer can get stuck by interference with the tubing internal diameter. Furthermore, some existing centralizers with vanes have cutout features, but such cutouts may get caught (or hung up) at tubing connections, resulting in the centralizer again potentially being stuck in the tubing and unable to go further into the tubing. Some existing centralizers, such as bow-spring centralizers, are typically designed for non-rotational applications and do not incorporate bearings (roller, thrust or otherwise), and, thus, such centralizers are generally not suitable for high speed rotational and/or long duration use. Thus, a centralizer that does not rely on rigid vanes, ribs or similar features to center a rod string due to the aforementioned issues, but can be rotationally fixed or coupled to the tubing and that can be utilized at coupling points of the rod string at high rotational velocities (e.g., 1000-4000 rpm) while providing the flexibility for use in internal areas/volumes of a tubing may be desirable.
The present application is generally related to centralizers and more particularly to a centralizer for use within long spanning cylindrical tube or pipe in high speed rotor dynamics applications. In an example embodiment, a centralizer for use in high speed rotor dynamics applications includes a housing having a first end portion and a second end portion. The centralizer further includes a rotatable shaft positioned within a cavity of the housing. The centralizer also includes flexure springs that are each attached to and extend between the first end portion and the second end portion. The flexure springs are compressible toward a middle portion of the housing that is between the first end portion and the second end portion. The centralizer further includes roller wheels attached to the flexure springs.
In another example embodiment, a system for use in high speed rotor dynamics applications includes a centralizer. The centralizer includes a cylindrical housing having a first end portion and a second end portion, a rotatable shaft positioned within a cavity of the cylindrical housing, and flexure springs that are each attached to and extend between the first end portion and the second end portion. The rotatable shaft is supported within and transmits loads to the cavity of the cylindrical housing via bearings (roller, thrust and/or otherwise). The flexure springs are compressible toward a middle portion of the cylindrical housing that is between the first end portion and the second end portion. The centralizer further includes roller wheels attached to the flexure springs. The system further includes a first rod attached to the centralizer and a second rod attached to the centralizer at an opposite side from the first rod.
These and other aspects, objects, features, and embodiments will be apparent from the following description and the appended claims.
Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The drawings illustrate only example embodiments and are therefore not to be considered limiting in scope. The elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the example embodiments. Additionally, certain dimensions or placements may be exaggerated to help visually convey such principles. In the drawings, the same reference numerals used in different drawings may designate like or corresponding but not necessarily identical elements.
In the following paragraphs, particular embodiments will be described in further detail by way of example with reference to the drawings. In the description, well-known components, methods, and/or processing techniques are omitted or briefly described. Furthermore, reference to various feature(s) of the embodiments is not to suggest that all embodiments must include the referenced feature(s).
The present application is generally related to centralizers and more particularly to a centralizer for use within a cylindrical tube or pipe in high speed rotor dynamics applications.
In some example embodiments, each flexure spring of the centralizer 100 may include a spring element that includes attachment end portions that are attached to respective mounting structures of the housing 102. For example, the flexure spring 104 extends between the end portions 112, 114 spaced from a middle portion 116 of the housing 102 that is between the end portions 112, 114. To illustrate, the flexure spring 104 may include an attachment end portion 126 that is attached to the mounting structure 118 using, for example, a clevis pin 130. The flexure spring 104 may also include an attachment end portion 128 at an opposite end of the flexure spring 104 that is attached to the mounting structure 120 using, for example, a clevis pin 132. The flexure spring 106 and the third flexure spring may be similarly attached to mounting structures at the end portions 112, 114 using clevis pins and may extend between the end portions 112, 114 spaced from the middle portion 116 of the housing 102 in a similar manner as the flexure spring 104.
In some example embodiments, two roller wheels may be attached to each flexure spring of the centralizer 100. For example, roller wheels 134, 136 may be attached to the flexure spring 104 and may be oriented to facilitate the movement/insertion of the centralizer 100 in longitudinal directions through a tubing and to resist the rotation of the housing 102 of the centralizer 100 in the tubing. The roller wheels 134, 136 may be rotatably attached to the flexure spring 104 using, for example, a respective clevis wheel such as a clevis pin 138. When the centralizer 100 is positioned in a tubing, the wheels 134, 136 may be in contact with the inner surface of the tubing such that the flexure spring 104 is compressed toward the middle portion 116 of the housing 102, and applies a preload that is intended to rotationally fix or couple the centralizer to the tubing. The roller wheels 134, 136 may be attached to the flexure spring 104 such that the wheels 134, 136 extend radially beyond the flexure spring 104 with respect to a center axis through of the cylindrical housing 102.
In some example embodiments, roller wheels 140, 142 may be similarly attached to the flexure spring 106 using respective clevis pins. The roller wheels 140, 142 may also radially extend beyond the flexure spring 106 in a similar manner as described with respect to the wheels 134, 136. Another pair of roller wheels may also be attached to the third flexure spring of the centralizer 100 and may radially extend beyond the third flexure spring.
In some example embodiments, the centralizer 100 may be mounted to rods using the couplers 108, 110. For example, each coupler 108, 110 may be threaded to receive a threaded end of a respective rod. As explained below with respect to
During operations, the centralizer 100 may be placed in a tubing such that the roller wheels attached to the flexure springs come in contact with the tubing and the flexure springs are compressed by the tubing toward the middle portion 116 of the housing 102. Because of the orientations of the flexure springs, including the flexure springs 104, 106, the housing 102 of the centralizer 100 along flexure springs may remain rotationally static while the centralizer 100 moves through the tubing and/or the couplers 108, 110 along with respective attached rods rotate.
By using the roller wheels that are attached to the flexure springs, the centralizer 100 facilitates the longitudinal movement of the centralizer 100 in a tubing while restraining the rotation of the centralizer 100 in the tubing by virtue of counteracting force exerted by the compressed flexure springs. In contrast to centralizers that use fixed and rigid vanes to provide lateral restraints, the use of the roller wheels attached to the flexure springs enables the centralizer 100 to be moved through a tubing with relatively reduced risk of getting stuck, for example, at tubing joints while enabling the relatively high speed rotation of rods attached to the couplers 108, 110. Further, by providing an open space (i.e., no vanes) between adjacent flexure springs, fluid may flow pass on the outside of the centralizer 100 with relatively less obstruction compared to centralizers that have fixed vanes.
In some example embodiments, the housing 102 may be made from aluminum or another suitable material using methods known by those of ordinary skill in the art with the benefit of this disclosure. In some example embodiments, the flexure springs 104, 106, etc. and the couplers 108, 110 may be made from steel or another suitable material using methods known to those of ordinary skill in the art with the benefit of this disclosure. In some example embodiments, the roller wheels may be made from aluminum or another suitable material using methods known by those of ordinary skill in the art with the benefit of this disclosure.
In some example embodiments, the flexure springs can have a coil, compression, extension, or torsional configuration without departing from the scope of this disclosure. In some example embodiments, the flexure springs may each be a leaf spring or another type of spring. In some alternative embodiments, more or fewer than two roller wheels can be attached to each flexure spring without departing from the scope of this disclosure. In some example embodiments, the centralizer 100 may include more than three flexure springs and more than three corresponding pairs of mounting structures without departing from the scope of this disclosure. In some alternative embodiments, other attachment elements instead of or in addition due clevis pins may be used to attach the flexure springs to the housing 102 and to attach the roller wheels to the flexure springs. In some alternative embodiments, the flexure springs 104, 106, etc. may be attached to the end portions 112, 114 using structures other than the mounting structures, such as the mounting structures 118, 120, 122, 124, etc.
In some example embodiments, the centralizer 100 may include a bearing 202 at each end portion 112, 114, where each end portion of the shaft 214 extends through the respective bearing 202.
In some example embodiments, the centralizer 100 may also include a retaining ring 204 to retain the respective bearing 202 at each end portion 112, 114 of the housing 102. The centralizer 100 may also include a retaining ring 206, a seal backing ring 208, a shaft seal 210, and another retaining ring 212 at each end portion 112, 114. Each retaining ring 204, 206, 212 may be at least partially positioned around a respective end portion of the shaft 214. Each seal backing ring 208 and each shaft seal 210 may be positioned around a respective end portion of the shaft 214. The cavity of the housing 102 may be hermetically sealed by the shaft seal 210 at the end portions 112, 114. The sealed cavity of the housing 102 may serve as a reservoir for containing a lubricant to lubricate the bearing 202 at each end portion 112, 114, which can result in reduced friction and heat and prolong the life of the components of the centralizer 100.
In some example embodiments, each retaining ring 204 retains the respective bearing 202 in place around the shaft 214 at the respective end portion 112, 114 of the housing 102. For example, the retaining ring 204 may be positioned in an anular groove formed in the shaft 214 as shown in
As more clearly shown in
In general, the bearing 202 may be or may be replaced with a roller bearing, a thrust bearing, a journal bearing, or generally a type including high temperature graphite, ceramic, polycrystalline diamond, tungsten carbide, and magnetic bearing types. In some example embodiments, a polycrystalline diamond bearing may be used in place of the bearing 202, where each bearing at the end portions 112, 114 is unsealed such that fluid freely flows through the bearing interfaces and enabling generated frictional heat to be transferred to the fluid. In some alternative embodiments, the centralizer 100 may include different components and/or a different arrangements of the components than shown in
As shown in
As shown in
In some example embodiments, the clevis pin 130 extends through an elongated attachment hole 502 at the end portion 126 of the flexure spring 126. For example, the clevis pin 130 may extend through the attachment hole 502 as well as through holes in the mounting structure 118 at the end portion 112 of the housing 102.
In some example embodiments, the shaft 214 may be made from aluminum or another suitable material using methods known by those of ordinary skill in the art with the benefit of this disclosure. For example, the shaft 214 may be made using milling and/or other methods. In some alternative embodiments, the shaft 214 may have a different shape than shown without departing from the scope of this disclosure.
In some example embodiments, the ramp portion 710 may be slated to facilitate the flow of fluid around the housing 102. The other mounting structures of the housing 102, such as the mounting structures 120-124, are substantially similar to the mounting structure 118.
In some example embodiments, the mounting structures at each end portion 112, 114 are spaced 120 degrees around the housing 102 when the centralizer 100 includes three mounting flexure springs. In general, the mounting structures are spaced equally around the housing 102. The spaces between adjacent mounting structures at the same end portion 112 or 114 of the housing 102 generally left unoccupied to facilitate the flow of fluid around the housing 102.
In some example embodiments, the shaft 214 extends through the cavity 714 of the housing 102 extend beyond the openings of the housing 102 at the end portions 112, 114 of the housing 102. For example, the end portion 402 of the shaft 214 shown more clearly in
In some alternative embodiments, the housing 102 may have a different shape than shown without departing from the scope of this disclosure. In some alternative embodiments, the mounting structures, such as the mounting structures 118-124, may have a different shape and/or configuration that shown without departing from the scope of this disclosure. In some alternative embodiments, the flexure springs of the centralizer 100 may be attached to the end portions 112, 114 of housing 102 in a different manner than described above without departing from the scope of this disclosure.
In some example embodiments, the flexure spring 802 may include narrow sections 818, 820 and a wide section 816 that is between the narrow sections 818, 820. The wide section 816 may include slots 822, 824, where a respective roller wheel can be positioned in each slot 822, 824. For example, the slot 822 may correspond to the slot 216 shown in
In some example embodiments, the narrow sections 818 are geometry primarily utilized and defined to obtain a specific spring rate, which dictates the amount of preload applied when the centralizer 100 is inserted into the tubing for any given application. The thicker the section 810, the higher the spring rate and thus the higher the preload. In some example embodiments, the narrow sections 818, 820 may also help reduce the resistance to the flow of fluid around the centralizer 100 in contrast to a flexure spring that is entirely or mostly as wide as the wide section 816. In general, the flexure spring 802 may have curved joints between adjoining surfaces where applicable to reduce resistance to fluid flow on the outside of the housing 102. In some alternative embodiments, the flexure spring 802 may have a different shape than shown without departing from the scope of this disclosure. In some alternative embodiments, the attachment holes 810-814 may each have a different shape than shown without departing from the scope of this disclosure.
In some alternative embodiments, instead of fully separating the attachment holes 902, 906 from each other, the middle section 908 may have include a channel 910 that provides a path for fluid to flow between the attachment holes 902, 906. For example, the shaft 214 may be hollow and may allow a fluid to flow therethrough, and the fluid flowing through the shaft 214 mass through the coupler 900 through the channel 910. Alternatively, or in addition, the channel 910 may allow some of the fluid flowing on the outside of the housing 102 to pass through the coupler 900.
In some alternative embodiments, the coupler 900 may have a different shape and/or different features than shown without departing from the scope of this disclosure. In some example embodiments, the threaded holes 902, 906 may be partially threaded. Alternatively, the threaded holes 902, 906 may be fully threaded. In some example embodiments, the threaded holes 902, 906 may be different sizes without departing from the scope of this disclosure.
In some example embodiments, the rods 1202, 1204 may be standard rods or may be non-standard (e.g., tubular/hollow, pre-balanced, etc.), and the couplers 108, 110 may be designed to accommodate various connection types (e.g., API, Proprietary Service, etc.). As described above, the shaft 214 may also be hollow such that the rods 1202, 1204 are fluidly coupled through the shaft 214 and the couplers 108, 110. In some alternative embodiments, the rods 1202, 1204 may be attached to the centralizer 100 in a different manner than shown without departing from the scope of this disclosure.
In some example embodiments, the longitudinal orientation of the roller wheels with respect to the tubing 1302 resists the rotational motion of the housing 102 and the flexure springs 104, 106, 302 with respect to the tubing while facilitating the axial insertion and movement of the centralizer 100 through the tubing 1302. To illustrate, the preload forces on the flexure springs 104, 106, 302 result in friction between the roller wheels attached to the flexure springs 104, 106, 302 and the tubing 1302, where the friction resists the rotational motion of the housing 102 and the flexure springs 104, 106, 302 with respect to the tubing 1302. As can be seen in
Because the shaft 214 is rotatable relative to the housing 102 that can remain generally rotationally static and because the shaft 214 is attached to the couplers 108, 110 that are also coupled to the rods 1202, 1204, the shaft 214 rotates along with the rods 1202, 1204. The shaft 214 and the rods 1202, 1204 may be coupled to couplers 108, 110 to rotate in a desired direction.
In some example embodiments, multiple ones of the centralizer 100 may be placed in the tubing 1302, where adjacent ones are connected by a respect rod or rod strings and spaced from each other, for example, in a range of about 5 feet to about 30 feet.
In some example embodiments, the retaining rings 206, 212, the seal backing ring 208, and the shaft seal 210 may also be at least partially positioned around the end portion of the shaft 214. The retaining rings 206, 212 may retain the seal backing ring 208 and the shaft seal 210 in place. The cavity 714 of the housing 102 may be hermetically sealed by the shaft seal 210, and the cavity 714 may serve as a reservoir for containing a lubricant to lubricate the bearing 202. As described above, in some alternative embodiments, a different type of bearing may be used than the bearing 202 without departing from the scope of this disclosure.
As more clearly shown in
In some example embodiments, the rods 1202, 1204 may be attached to the shaft 214 using means other than or in addition to the couplers 108, 110 without departing from the scope of this disclosure. In some alternative embodiments, the centralizer 100 may include more than three flexure springs without departing from the scope of this disclosure. In some alternative embodiments, the flexure springs 104, 106, 302 may be attached to the housing 102 in a different manner than shown in the figures without departing from the scope of this disclosure.
As shown in
In some example embodiments, the flexure springs 1504, 1506, 1516 are 120 degrees apart around the housing 1502. In contrast to the flexure springs of the centralizer 100 of
In some example embodiments, a shaft 1510 may extend through a cavity of the housing 1502, where end portions of the shaft 1510 are positioned outside of the housing 1502 and a middle portion of the shaft 1510 is inside the housing 1502. The shaft 1510 may be attached to a coupler 1508 at one end of the shaft 1510. For example, the coupler 1508 may correspond to the coupler 108 shown in
In general, the components of the centralizer 1500 may be made from the same material as described with respect to the centralizer 100. In some example embodiments, some of the components of the centralizer 1500 may have different shapes than shown without departing from the scope of this disclosure. In some alternative embodiments, some of the components of the centralizer 1500 may be used instead of or in addition to the components of the centralizer 100 without departing from the scope of this disclosure. In some example embodiments, the centralizer 1500 may be used instead of the centralizer 100 without departing from the scope of this disclosure.
Referring to
Although some embodiments have been described herein in detail, the descriptions are by way of example. The features of the embodiments described herein are representative and, in alternative embodiments, certain features, elements, and/or steps may be added or omitted. Additionally, modifications to aspects of the embodiments described herein may be made by those skilled in the art without departing from the spirit and scope of the following claims, the scope of which are to be accorded the broadest interpretation so as to encompass modifications and equivalent structures.
The present application claims priority under 35 U.S.C. Section 119(e) to U.S. Provisional Patent Application No. 62/881,469, filed Aug. 1, 2019 and titled “High Speed Rotor Dynamics Centralizer,” and to U.S. Provisional Patent Application No. 63/051,716, filed Jul. 14, 2020 and titled “Artificial Lift Systems Utilizing High Speed Centralizers,” The entire contents of the foregoing applications are hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
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| PCT/US2020/044351 | 7/30/2020 | WO |
| Publishing Document | Publishing Date | Country | Kind |
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| WO2021/022091 | 2/4/2021 | WO | A |
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