Patent Application
20100272504
1. Field of Invention
The present invention relates generally to the field of fluid transfer, and more specifically to submersible and surface pump apparatus and systems and methods of making and using same.
2. Related Art
Vertical and horizontal centrifugal pump systems are designed to operate in downthrust mode, where pressure inside the pump case by action of the pump impellers tends to exert an axial force on the pump shaft toward the suction inlet. Most pump and motor manufacturers instruct users not to operate these pumps in upthrust mode, where pressure exerted by pumped fluid against the impellers at the suction inlet may result in damaged impellers, a damaged pump shaft, and damaged pumps seals and bearings. Upthrust conditions may exist at startup, when operating at high flow rates, and/or when the specific gravity of the fluid being pumped changes. In the upthrust condition, bearings may not be cooled sufficiently due to lack of recirculation and may fail. Some pump manufacturers use a disk-type upthrust pad at the discharge/exit area of the pump to limit the upthrust movement of the shaft. Other pump manufactures have used combinations of a grooved upthrust pad in the diffuser and grooved radial bore in the diffuser to prevent the loss of lubrication to the bearing in the upthrust condition. These approaches are not always successful.
It is evident that there is a need in the art for pump apparatus and methods which more adequately address the upthrust condition problem.
In accordance with the present invention, coupling members, systems including same, and methods of making and using same are described that reduce or overcome problems in previously known apparatus and methods. Apparatus of the invention comprise a securing mechanism to limit upthrust, or limit the tendency of a pump shaft going into the upthrust condition, and therefore reduce or prevent failure. In systems of the invention one shaft, such as a pump shaft, is secured axially and rotationally to the coupling, and the coupling is in turn secured axially and rotationally to a second shaft, such as a thrust chamber shaft.
A first aspect of the invention is coupling members adapted to connect a first shaft, such as a pump shaft, with a second shaft, such as a thrust chamber shaft. The coupling members of the invention are adapted to connect a first shaft with a second shaft, the coupling member comprising means for transmitting rotational movement between the shafts and means for securing the shafts from substantial axial movement during rotation of the shafts and coupling member, the coupling member including at least one torque-limiting element. The first shaft may be a pump shaft while the second shaft may be a thrust chamber shaft, although the invention is not so limited. Any means for securing the first and second shafts to the coupling member may be used, including any combination of male/female connections, as long as the transmission of rotational motion and axial securing functions are achieved. For example, coupling member may have dual female receptacles for accepting ends of the shafts; one side of the coupling member may have a female receptacle while the other has a male portion connecting to a female portion of the other shaft, and so on. In certain embodiments, the coupling member defines a first axial chamber adapted to accept a first end of the first shaft, and a second axial chamber adapted to accept a first end of the second shaft, the axial chambers separated by a coupling plate, which in some embodiments has a through hole adapted to accept a male portion of an axial motion securing member, and in other embodiments is a solid plate. The means for transmitting rotational movement may be selected from splines, pins, bolts, rivets, clamps, rings, threads, grooves, gears, bearings, collets, or other equivalent functional elements. The coupling members may also include axial motion securing elements in the first and second axial chambers for axially securing the shafts in the coupling member.
For convenience only, the first shaft is hereinafter referred to as the pump shaft, and the second shaft is referred to as a thrust chamber shaft, however, those of skill in the art will recognize that the inventive coupling members, systems, and methods may be used when coupling any two rotating shafts.
The inventive coupling members may be used in systems of the invention, which comprise a second aspect of the invention. Systems of the invention comprise a coupling member connecting a first shaft with a second shaft, the coupling member comprising means for transmitting rotational movement between the shafts and means for securing the shafts from substantial axial movement during rotation of the shafts and coupling member, the coupling member including at least one torque-limiting element. In certain embodiments, the first end of the pump shaft, or a sub-shaft or component intermediate of the pump shaft first end is axially secured in the inventive coupling member. One way of accomplishing this is by virtue of a female aperture or receptacle extending inwardly from the pump shaft first end a certain distance and accepting a male portion of a pump shaft axial securing member, the female receptacle and the male portion of the pump shaft axial securing member being threaded in matching relationship. The pump shaft axial securing member may have a head, forming with the male portion a bolt. In these embodiments the male portion protrudes through a central through hole in a coupling plate and threadingly engages the threads in the female receptacle, while the head engages the coupling plate, thus axially securing the pump shaft to the coupling member upon tension forces, in other words, forces tending to move the pump shaft axially away from the coupling plate, such as during upthrust conditions.
Alternatively, systems of the invention include those wherein the female receptacle in the pump shaft first end may comprise one or more grooves, such as J grooves, while the male portion of the pump shaft adjusting member includes one or more radially extending pins or other protuberances, the pins sliding into matching respective grooves and engaging a portion of the groove to axially secure the pump shaft. Other shaped grooves may of course be used, as long as the securing function is achieved. In certain system embodiments the pump shaft may be axially secured to the coupling member by one or more pins inserted through matching transverse passages through walls of the coupling member which define the first chamber and through a corresponding transverse passage in the pump shaft. The pin or pins may be tapered, threaded their whole or a portion of their length, or held by cotter pins. The pins may comprise any shape and material sufficient to provide the axial securing function, that is, of retaining the axial position of the pump shaft and coupling member so that the pump and motor thrust bearings are not damaged by upthrust or other conditions. Alternatively, to avoid forming a passage through the pump shaft, the pump shaft may be modified on its outer surface proximate the first chamber inner wall to be threaded or accept a threaded collar which also has threads on its outer surface and mating with threads on the inner wall of the first chamber. A two-piece ring, a snap ring, or combination thereof, or other axial securing retainer, as described further herein, may be employed. Alternative embodiments include those wherein the pump shaft first end comprises a female receptacle, while the coupling member comprises a male member. Any of the mentioned securing means may be used in these embodiments.
In certain system embodiments the pump shaft axial securing member is adjustable, such as when the male portion is threaded and meshes with a threaded receptacle in the pump shaft or intermediate component, or when the pump shaft end is threaded or a threaded collar is used. This has certain advantages as will be discussed herein. In addition, one or more pump shaft shims may be positioned between the coupling plate and the first end of the pump shaft, the male portion of the pump shaft axial securing member passing through the shims and through the coupling plate. The pump shaft shims, if used, may comprise a material that is the same as or different from the coupling member material and the pump shaft. In certain embodiments the pump shaft, pump shaft shims, and coupling member are all of the same material. The pump shaft axial securing member head may include surfaces allowing the head to be turned by a tool, such as a wrench, screw driver or other tool. The pump shaft axial securing member head may or may not be the same material as the male portion.
Systems of the invention include those wherein the thrust chamber shaft is axially secured in the second chamber. In certain embodiments the thrust chamber shaft is axially secured to the coupling member by a two-piece ring and snap ring. Alternatively, one or more pins may be inserted through matching transverse passages through walls of the coupling member which define the second chamber and through a passage in the thrust chamber shaft. The pin or pins may be tapered, threaded, or held by cotter pins. The pins may be comprised of any shape and material sufficient to provide the axial securing function, that is, of axially securing the relative position of the thrust chamber shaft and coupling member so that the pump and motor thrust bearings are not damaged by upthrust or other conditions. Alternatively, to avoid forming a passage through the thrust chamber shaft, the thrust chamber shaft may be modified on its outer surface proximate the second chamber inner wall to be threaded or accept a threaded collar which also has threads on its outer surface and mating with threads on the inner wall of the second chamber. Alternative embodiments include those wherein the thrust chamber shaft first end comprises a female receptacle, while the coupling member comprises a male member. Any of the mentioned securing means may be used in these embodiments.
In embodiments employing a coupling plate, the coupling plate may be positioned anywhere internally of the coupling member as long as it separates the two chambers and serves the pump shaft axially securing function in conjunction with the pump shaft axial securing member. The coupling plate may be integral to the coupling member body or a separate piece inserted into the coupling member body. Further, the coupling plate is only required when using a bolt to secure the coupling member to one of the shafts. Apparatus and systems of the invention include those wherein the coupling member is cylindrical in shape, as are the first and second axial chambers. However, neither the axial chambers nor the portions of the shafts which fit therein are required to be cylindrical in shape. In fact, square shafts, hex shafts or any other of a number of configurations could be employed for engaging the chambers or shafts together. The coupling member and coupling plate (if present) may be all one and the same material, but this is not required. Combinations of different materials may be used as desired. The coupling plate may have two substantially parallel surfaces substantially perpendicular to the longitudinal axis of the pump shaft and thrust chamber shaft. In these embodiments the pump shaft axial securing member interacts with the coupling plate by way of a head that abuts against a surface of the coupling plate that faces the thrust chamber shaft. In other embodiments, the side of the coupling plate facing the thrust chamber shaft may have a recessed area that accepts the head of the pump shaft axial securing member so that it abuts the recessed area, allowing the first end of the thrust chamber shaft to be positioned substantially flush against the coupling plate. In certain embodiments the coupling plate is positioned approximately midway between the ends of the coupling member. Apparatus and systems of the invention include those wherein the first and second axial chambers of the coupling member have equal diameters, apparatus and systems wherein the chambers have different diameters, and apparatus and systems wherein one or both axial chambers have truncated conical shape.
Apparatus and systems of the invention include a torque-limiting feature functioning to physically break the coupling member upon exposure to excessive torque conditions. One such feature is a portion of the coupling member having a reduced thickness cross section, as described more fully herein. The reduced thickness cross section or sections may be positioned anywhere, but in certain embodiments it may be advantageous to place one reduced thickness portion approximately at the axial midpoint of the coupling member, or between the coupling plate (if present) and one of the ends of the coupling member, either on the thrust shaft side or the pump shaft side of the coupling member. Two or more reduced thickness portions may be envisioned in certain other embodiments. The reduce thickness cross sections may be annular grooves or depressions of any shape. Alternatively, or in conjunction with reduced thickness cross sections, apparatus and systems of the invention may include one or more radially and/or longitudinally extending shear pins. Another alternative is the use of spring-load mechanisms, such as spring-load ball and groove features.
Another aspect of the invention are methods of making a locked pair of shafts, one method of the invention comprising:
Methods of the invention include those wherein the selecting a coupling member to limit shaft movement includes calculating the width and/or number of shaft shims required to limit the axial shaft movement, and installing one or more shaft shims in the coupling by bolting or other means. In one embodiment, the first shaft is a pump shaft that is axially secured using a bolt and optional shaft shims, while the second shaft is a thrust chamber shaft that is secured axially to the coupling using one or more pins, bolts, or other means. In horizontal and other pumping systems, the pin (or bolt or screw) may be inserted through the intake of the pump.
Yet another aspect of the invention are methods of pumping fluids, one method comprising:
Apparatus and systems of the invention may be used downhole pumping systems, in submersible pump systems, and in horizontal pumping systems, and may be used between any two shafts in such systems, such as shafts between a driver and a pump, between two pump sections, between a pump and an auxiliary device such as an auger or other fluid transmission device. In pumping systems including motors, especially downhole pumping systems, the systems may include a motor protector, which may or may not be integral with the motor, and may include integral instrumentation adapted to measure one or more downhole parameters. Pump systems employing apparatus and systems of the invention may be adapted to produce a dynamic head up to 7,500 feet or more. The driver shaft may be one and the same as the pump shaft in certain embodiments, and in certain other embodiments the pump shaft may be mechanically coupled to and driven by the driver shaft. In other embodiments, the driver shaft and the pump shaft may be distinct and not be coupled mechanically, such as in magnetic couplings wherein the driver shaft drives a magnetic coupling comprising magnets on the driver shaft which interact with magnets in a protector, in which case the protector shaft mechanically connects to and drives the pump shaft.
Apparatus and methods of the invention will become more apparent upon review of the brief description of the drawings, the detailed description of the invention, and the claims that follow.
The manner in which the objectives of the invention and other desirable characteristics can be obtained is explained in the following description and attached drawings in which:
It is to be noted, however, that the appended drawings are not to scale and illustrate only typical embodiments of this invention, and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
All phrases, derivations, collocations and multiword expressions used herein, in particular in the claims that follow, are expressly not limited to nouns and verbs. It is apparent that meanings are not just expressed by nouns and verbs or single words. Languages use a variety of ways to express content. The existence of inventive concepts and the ways in which these are expressed varies in language-cultures. For example, many lexicalized compounds in Germanic languages are often expressed as adjective-noun combinations, noun-preposition-noun combinations or derivations in Romanic languages. The possibility to include phrases, derivations and collocations in the claims is essential for high-quality patents, making it possible to reduce expressions to their conceptual content, and all possible conceptual combinations of words that are compatible with such content (either within a language or across languages) are intended to be included in the used phrases.
The invention describes coupling members, systems incorporating same, and methods of making and using same for pumping fluids, for example, to and from wellbores, although the invention is applicable to pumps designed for any intended use, including, but not limited to, so-called surface fluid transfer operations. A “wellbore” may be any type of well, including, but not limited to, a producing well, a non-producing well, an experimental well, and exploratory well, and the like. Wellbores may be vertical, horizontal, some angle between vertical and horizontal, and combinations thereof, for example a vertical well with a non-vertical component. As discussed, vertical and horizontal centrifugal pump systems are designed to operate in downthrust mode, where pressure inside the pump case by action of the pump impellers tends to exert an axial force on the pump shaft toward the suction inlet. Most pump and motor manufacturers instruct users not to operate these pumps in upthrust mode, where pressure exerted by pumped fluid against the impellers at the suction inlet may result in damaged impellers, damage the pump shaft, and damaged pumps seals and bearings. Upthrust conditions may exist at startup, when operating at high flow rates, and/or when the specific gravity of the fluid being pumped changes. In the upthrust condition, bearings may not be cooled sufficiently due to lack of recirculation and may fail. Previous approaches to solving these problems are not always successful.
Given that there is considerable investment in existing equipment, it would be an advance in the art if upthrust conditions and their consequences could be avoided or reduced, and further if a torque-limiting feature could be included, so that more expensive components, such as shafts, do not fail before less expensive components, such as couplings. This invention offers methods and apparatus for these purposes. A torque-limiting element is placed in the coupling members of the invention for the purpose of having the coupling “fail” at a specified torque value generally less than the value needed to “fail” either of the shafts. “Failure”, as used herein, means limiting the ability of the coupling to transmit torque between the two shafts. This can be accomplished in any number of ways including appropriate choice of a coupling material(s), employing the use of one or more grooves on the OD or ID of the coupling having a variable length and depth so as to limit the cross sectional area and thus the strength of the coupling to a predetermined value. The depth of the grooves may be equal to zero depending on the design and/or choice of material. Use of one or more radial or longitudinal “shear” pins may provide the torque-limiting feature. Another means for torque limiting employs the use of a press fit member designed to slip under a given torsional load. Spring loaded mechanisms and cam loaded mechanisms may be used. Any combination of these means may be employed in a given situation.
In use, pump shaft 22 movement in upthrust and downthrust conditions may be measured. Shaft shims 44 having a central through hole through which shaft 36 threadedly fits may be employed as desired. Based on the measured or observed axial movement of pump shaft 22, the length (or number) of shaft shims 44 required is calculated so that pump shaft 22 has limited movement. During installation, the required number of shaft shims 44 and pump shaft 22 are bolted to coupling member 35 with bolt 26, 42. The pump is then installed, for example in a horizontal skid. Pump shaft 22 is rotated so that the radial hole 45 in coupling member 35 and though hole 51 in thrust chamber shaft 20 match. Pin 49, which may also be a bolt, or screw, is used to secure coupling member 35 with thrust chamber shaft 20. The securing device may be installed through pump intake 6.
In certain embodiments of the invention, a variety of seals, filters, absorbent assemblies and other protection elements may be used to protect motors and other components, particularly if the apparatus and systems of the invention are to used in downhole applications. These components are not illustrated for clarity, but may include, for example, one or more thrust bearings disposed about shafts 20 and 22 to accommodate and support the thrust load from pump 4. A plurality of shaft seals may also disposed about shaft 20 between pump 4 and motor 2 to isolate a motor fluid in motor 2 from external fluids, such as well fluids and particulates. Shaft seals also may include stationary and rotational components, which may be disposed about the shafts in a variety of configurations. Systems of the invention also may include a plurality of moisture absorbent assemblies disposed throughout housings between a pumps and a motor. These moisture absorbent assemblies absorb and isolate undesirable fluids (for example, water, H2S, and the like) that have entered or may enter housing through shaft seals or though other locations. For example, moisture absorbent assemblies may be disposed about shaft 20 at a location between pump 4 and motor 2. In addition, the actual protector section above the motor may include a hard bearing head with shedder.
Another apparatus and system embodiment 400 is illustrated schematically in
FIGS. 19 and 19A-19D illustrate another embodiment of the invention. Spline connections 28 and 30 are used for torque transfer, while internal circular push on rings 48 and 48′, as well as internal snap rings 50 and 50′ secure shafts 20 and 22 axially to coupling member 35. Snap ring 50 fits into a groove 133 in coupling member 35, while snap ring 50′ fits into a groove 85′ in coupling member 35.
Apparatus, systems, and methods of the invention may be employed in a variety of applications, such as in horizontal pumping systems (“HPS”), such as illustrated generally in
As explained in assignee's U.S. Pat. No. 6,425,735, the motor may be fixedly coupled to horizontal skid at a motor mount surface of the horizontal skid. The pump may be coupled to the horizontal skid by a mount assembly, which may include a support (e.g., a fixed support) and clamp assemblies. The pump may be drivingly coupled to the motor through support. Alternatively, the support may be an external conduit assembly configured for attachment to a pump conduit, such as one of two pump conduits extending from the pump. Pumping systems of the invention may displace water, salt water, sewage, chemicals, oil, liquid propane, or other fluids in through one of the pump conduits and out of another pump conduit. In addition, the temperature of the fluids may vary. For example, some applications may involve pumping hot fluids, while others may involve pumping cold fluids. In addition, the temperature may change during the pumping operation, either from the source of the fluid itself, or possibly due to the heat generated by the operation of the pump and/or driver. In addition, temperature may change dramatically due to weather change.
Electrical submersible pumps (“ESP”), such as pumping systems known under the trade designation Axia™, available from Schlumberger Technology Corporation, may be modified in accordance with the teachings of the invention. Pumps of this type may feature a simplified two-component pump-motor configuration, with pump having one or more stages inside a housing, and a combined motor and protector. The pump may be built with integral intakes and discharge heads. Fewer mechanical connections may contribute to faster installation and higher reliability of this embodiment. The combined motor and protector assembly, known under the trade designation ProMotor™, may be prefilled in a controlled environment, and may include integral instrumentation that measures downhole temperatures and pressures.
An alternative electrical submersible pump configuration in which apparatus and systems of the invention may be employed include an ESP deployed on cable, an ESP deployed on coiled tubing with power cable strapped to the outside of the coiled tubing (the tubing acts as the producing medium), and more recently a system known under the trade designation REDACoil™ having a power cable deployed internally in coiled tubing. For example, three “on top” motors may drive three pump stages, all pump stages enclosed in a housing. The pump stages may be identical in number of pump stages and performance characteristics, while some pump stages may have different performance characteristics. A separate protector may be provided, as well as an optional pressure/temperature gauge, sub-surface safety valve (SSSV) and a chemical injection mandrel. The technology of bottom intake ESPs (with motor on the top) has been established over a period of years. It is important to securely install pump stages, motors, and protector within coiled tubing, enabling quicker installation and retrieval times plus cable protection and the opportunity to strip in and out of a live well. This may be accomplished using a deployment cable, which may be a cable known under the trade designation REDACoil™, including a power cable and flat pack with instrument wire and one or more, typically three hydraulic control lines, one each for operating the lower connector release, SSSV, and packer setting/chemical injection.
Apparatus and systems of the invention may include many optional items. One optional feature of apparatus and systems of the invention is one or more sensors located at the protector to detect the presence of hydrocarbons (or other chemicals of interest) in the internal lubricant fluid. The chemical indicator may communicate its signal to the surface over a fiber optic line, wire line, wireless transmission, and the like. When a certain chemical is detected that would present a safety hazard or possibly damage the motor if allowed to reach the motor, the pump may be shut down long before the chemical creates a problem.
Typical uses of apparatus and systems of the invention will be in downhole and surface fluid transfer applications.
Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, no clauses are intended to be in the means-plus-function format allowed by 35 U.S.C. §112, paragraph 6 unless “means for” is explicitly recited together with an associated function. “Means for” clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11164301 | Nov 2005 | US |
| Child | 12830540 | US |
