EP1379756A1 - Procede de pompage de fluides - Google Patents

Procede de pompage de fluides

Info

Publication number
EP1379756A1
EP1379756A1 EP02709817A EP02709817A EP1379756A1 EP 1379756 A1 EP1379756 A1 EP 1379756A1 EP 02709817 A EP02709817 A EP 02709817A EP 02709817 A EP02709817 A EP 02709817A EP 1379756 A1 EP1379756 A1 EP 1379756A1
Authority
EP
European Patent Office
Prior art keywords
motor
houow
fluid
rotor shaft
fluids
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02709817A
Other languages
German (de)
English (en)
Other versions
EP1379756A4 (fr
Inventor
Michael G. Hartman
Eric M. Moe
Robert Breidenthal
Jesse S. Rehr
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Centriflow LLC
Original Assignee
Centriflow LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US09/838,744 external-priority patent/US20020153141A1/en
Application filed by Centriflow LLC filed Critical Centriflow LLC
Publication of EP1379756A1 publication Critical patent/EP1379756A1/fr
Publication of EP1379756A4 publication Critical patent/EP1379756A4/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/12—Methods or apparatus for controlling the flow of the obtained fluid to or in wells
    • E21B43/121—Lifting well fluids
    • E21B43/128—Adaptation of pump systems with down-hole electric drives

Definitions

  • the present invention relates to methods for pumping fluids, primarily from wells.
  • Water, oil and natural gas are commonly produced in wells.
  • the wells are formed by drilling a hole into a rock formation to the depth where the fluid reservoir lies.
  • a well casing is inserted into the hole following the drilling. If natural gas is present in the well, it is readily recovered from the well due to its natural buoyancy, while in most cases water and oil must be pumped to the surface.
  • ESP electrical submergible pumps
  • An ESP includes an electric motor that drives a submergible pump that forces fluids from the reservoir to the surface.
  • ESPs are often remotely operated in wells commonly at great depths, in harsh environmental conditions.
  • a challenge in using ESPs is effective heat removal. Resistance in the electric motor windings generates a significant amount of waste heat in operation, as do mechanical friction and fluid friction. If this waste heat is not sufficiently removed, the motor temperature can rise significantly. Increasing the motor temperature leads to a number of problems. Motor life becomes considerably shorter as temperatures increase. Motor winding insulation, bearings, seals, and lubrication are all adversely affected by high temperature.
  • ESPs commonly are removed from wells more often than desired in order to replace or repair the electric motor. In the oil market in particular, this results in high maintenance and repair costs as well as significant losses of revenue due to lost production.
  • the ESP system includes pump 3, motor 4 and seal section 5. Production fluids enter the well at a point below or near the bottom of motor 4, pass by motor 4 in the direction indicated by arrows 8, and then enter pump 3 at pump intake 6. The production fluids are forced upwardly by pump 3, exiting at the top of pump 3 and traveling to the surface in the direction indicated by arrow 9. Cable 10 provides electrical power to motor 4 from the surface. As shown, a packer 16 may be used in the assembly.
  • an improved ESP system would be highly desirable, particularly one which enables more effective and efficient heat removal from the electrical motor particularly if this can be achieved without the expense of additional components or unnecessary features.
  • a further concern in many wells is the separation of liquids and gasses. This problem is often seen in wells that produce both natural gas and oil. Pumping a gas/liquid mixture creates inefficiencies that can be avoided if the gasses and liquids can be separated easily before the liquids enter the pump intakes. It would be desirable to provide a method by which gaseous and liquid fluids can be easily and inexpensively separated before the liquids enter a pumping system.
  • this invention is method of pumping a fluid with a submergible pumping system including a pump and an electrical motor, wherein the electrical motor has a hollow rotor shaft and said pumping system is adapted to pump at least a portion of said fluid through said hollow rotor shaft, and wherein at least a portion of said fluid passes in fluid contact with exterior portions of the electrical motor and remove heat from the electrical motor.
  • this invention is a method of pumping fluids with a submergible pumping system including a pump and an electrical motor, wherein (a) the electrical motor has a hollow rotor shaft and said pumping system is adapted to pump said fluid through said hollow rotor shaft, and (b) the pumping system is submerged in said fluid such that production fluids entering the pumping system pass in fluid contact with exterior portions of the electrical motor and remove heat therefrom before entering the production fluid intakes, and said production fluids then pass through the hollow rotor shaft of the electrical motor as the fluid is pumped, and remove additional heat from the motor.
  • this invention is a method for pumping fluids from a well having a casing that contains perforations through which production fluids enter the well, comprising
  • the pumping system includes a pump, an electrical motor having a hollow rotor shaft and production fluid intakes located below said electrical motor, said pumping system being adapted to pump said production fluids through said hollow rotor shaft of the electrical motor, (ii) liquid production fluids entering the well through at least some of the perforations in the well casing come into fluid contact with exterior portions of the electrical motor and remove heat therefrom before entering the production fluid intakes, and (i ⁇ ) liquid production fluids pass through the hollow rotor shaft of the electrical motor as the fluid travels toward the wellhead, and remove additional heat ⁇ from the motor.
  • this invention is a method comprising pumping a fluid with a submergible pumping system including a pump and an electrical motor, wherein (a) the electrical motor has a hollow rotor shaft and the pumping system has a fluid intake below the electrical motor in liquid communication with said hollow rotor shaft; (b) the pumping system has at least one outlet located at or below the electrical motor, said outlet being in liquid communication with the fluid intake; (c) the pumping system is submerged in a well having a well casing;
  • the cross-section of the electrical motor is such that the electrical motor fits within the well casing and a space is defined between the well casing and exterior of the electrical motor; and said pumping system is adapted so that during operation a portion of the fluid entering the fluid intake is pumped through the hollow rotor shaft, and a portion of the fluid entering the fluid intake is pumped through the outlet and upwardly in fluid contact with the of outside of the electrical motor in the space defined between the well casing and the exterior of the electrical motor.
  • this invention is a method of pumping a fluid from a well having a wellhead and a well casing, using a submergible pumping system including a pump and an electrical motor, comprising (I) positioning a pumping system in a well with the pump being located between the electrical motor and the wellhead; wherein (a) electrical motor has a hollow rotor shaft which is in liquid communication with the pump,
  • the cross-section of the electrical motor is such that the electrical motor fits within the well casing and a space is defined between the well casing and the electrical motor;
  • the pumping system has a first fluid intake in liquid communication with said hollow rotor shaft;
  • the pumping system has a second fluid intake above the motor in liquid communication with the space defined between the well casing and the electrical motor, with the at least one outlet located at or below the electrical motor, said outlet being in liquid communication with the fluid intake; and (II) operating said pumping system under conditions such that during operation a portion of the fluids enter said first fluid intake and is pumped through the hollow rotor shaft of the electrical motor, and a second portion of the fluids are pumped through the space defined between the well casing and the electrical motor and in fluid contact with the exterior of the electrical motor to enter the second fluid intake, and said first and second portions of the fluids are then pumped to the wellhead.
  • Production fluids in laminar or turbulent flow that come into fluid contact with the exterior of the electrical motor provide heat removal.
  • the increased flow rate made possible by operating the ESP below the perforations may foster turbulent flow in the annulus between the motor housing and the well casing, contributing to a significant increase in heat transfer.
  • An additional cooling effect is seen when the production fluids pass through the hollow rotor shaft; thus, the production fluids are used to remove heat twice in this invention, once as they pass outside of the motor and a second time as they pass through hollow rotor shaft.
  • the combined cooling effects help maintain the motor within optimal or desired temperature limits. This prolongs motor life and reduces maintenance costs and other expenses attributable to premature motor failure.
  • the cooling effect can be further facilitated if the pump and/or hollow rotor shaft is designed so that the production fluids experience turbulent flow as they pass through the hollow rotor shaft.
  • the combined cooling effect of the well fluids passing the outside of the motor and through the hollow rotor shaft of the motor provides advantages such as prolonged motor life, increased horsepower density and/or greater electrical efficiency. It often provides combinations of these benefits.
  • this invention is a method of pumping fluids with a submergible pumping system including a pump and an electrical motor, wherein the pumping system is submerged in said fluid such that production fluids entering the pumping system pass in fluid contact with exterior portions of the electrical motor and remove heat therefrom before entering the production fluid intakes, wherein the exterior portions of the electrical motor or the interior portions of a surrounding shroud include vortex generators adapted to impart streamwise vorticity to the production fluids as they pass in fluid contact with the exterior portions of the electrical motor.
  • This aspect of the invention provides an economical means for substantially increasing the efficiency of heat removal from the motor.
  • This aspect of the invention can be incorporated into the first and second aspects of the invention.
  • this invention is a mechanism for providing motive force, the mechanism comprising (I) a power unit including:
  • a hollow rotor shaft having a longitudinal axis and opposite ends, the hollow rotor shaft being rotatably mounted within the housing for rotation of the hollow rotor shaft relative to the housing, substantially about the longitudinal axis of the hollow rotor shaft;
  • a drive system mounted within said housing connected to the hollow rotor shaft for causing rotation of the hollow rotor shaft relative to the housing, wherein the drive system includes a plurality of magnets mounted within the housing, located around the hollow rotor shaft, wherein the magnets create magnetic forces for causing the hollow rotor shaft to rotate relative to the housing; and (II) a pumping unit located below the power unit, wherein
  • the pumping unit includes a longitudinal hollow drive shaft that is in fluid communication with the hollow rotor shaft in the power unit, the hollow drive shaft being rotated substantially about its longitudinal axis when the hoUow rotor shaft is rotated;
  • the hollow drive shaft has a shaft inlet proximate to its bottom portion for allowing fluids being pumped to enter the hollow drive shaft;
  • the pumping unit has fluid intakes proximate to a topmost portion of the pumping unit, through which fluids being pumped enter the pumping unit; the fluid intakes, hollow drive shaft, shaft inlet and impellers being adapted such that when the hollow drive shaft is rotated about its longitudinal axis, fluids are pumped into the pumping unit through said fluid intakes, downwardly within the pumping unit to the shaft inlet of the hollow drive shaft, and then through the hollow drive shaft of the pumping unit and through the hollow rotor shaft of the power unit.
  • this invention is a method of removing a mixture of gaseous and Kquid fluids from a well having at least one point where a mixture of gaseous and fiquid fluids enter the well, comprising (I) positioning a pumping system in the well above the point or points where the mixture of gaseous and Uquid fluids enter the well, wherein:
  • the pumping system includes at least one power unit, at least one pumping unit, and at least one intake through which fluids being pumped enter the pumping system;
  • the power unit includes an electric motor having a hollow rotor shaft in fluid communication said intake, and the pumping system is adapted such that fluids entering the intake are pumped through the hollow rotor shaft of the power unit;
  • the intake is located below at least a portion of the pumping system and is of smaller diameter than at least that portion of the pumping system above the intake;
  • FIG. 1 is a schematic view of two conventional ESP systems.
  • FIGs. 3 and 3A represent a schematic view and deta ⁇ of an embodiment of a motor having vortex generators for use in preferred aspects of the invention.
  • Figures 4-6 are cross-sectional views of embodiments of various aspects of the invention.
  • a submergible pumping system is used to pump a fluid.
  • the system includes a pump and an electrical motor.
  • the electrical motor has a hollow rotor shaft and said pumping system is adapted to pump said fluid through said hollow rotor shaft.
  • External cooling is also provided by the production fluids.
  • the pumping system is submerged in the fluid such that production fluids entering the pumping system pass exterior portions of the electrical motor and remove heat therefrom before entering the production fluid intakes, and said production fluids then pass through the hollow rotor shaft of the electrical motor as the fluid is pumped, and remove additional heat from the motor.
  • the conditions of the fluid flow are preferably such that the fluid flow is turbulent, has streamwise vortices, or both as the fluid passes the exterior portions of the electrical motor, and is turbulent as it passes through the hollow rotor shaft.
  • the production fluids are sp ⁇ t as they are pumped, with some being pumped through a hollow rotor shaft and the remainder being pumped past the exterior surface of the motor.
  • the pumping system is installed in a well, or else has a mechanical means for inducing the fluid to pass in fluid contact with exterior portions of the electrical motor.
  • a mechanical means is a shroud which partially covers the pumping system, and has an opening to the fluid being pumped at the opposite end of the pumping system from where the production fluid intakes are located.
  • This shroud permits the fluids to pass in fluid contact with the exterior portions of the electric motor and enter the production fluid intakes.
  • the spacing between the shroud and the exterior portions of the electrical motor is preferably such that the fluids exhibit turbulent flow as they pass in fluid contact with the exterior of the motor and do not impair installation in the well or create excessive head loss.
  • vortex generators impart streamwise vortices to the production fluids as they flow through the spacing between the shroud and the exterior portions of the electrical motor.
  • the pumping system is installed in a well.
  • the well may be vertical, horizontal, or a so-called "divert" type.
  • the well has a casing that has perforations through which production fluids enter the well.
  • the pumping system includes an electrical motor having a hollow rotor shaft.
  • the pumping system has production fluid intakes through which the production fluids enter. These are located below said electrical motor (in the case of a horizontal well, opposite from the wellhead).
  • the pumping system is adapted to pump said production fluids through the hollow rotor shaft of the electrical motor and then on to the wellhead.
  • production fluids any fluids which are desired to be withdrawn from the well.
  • examples of such fluids include water, oil, natural gas, and the like, with liquids being of particular interest and o ⁇ being of special interest.
  • perforations it is merely meant openings in a well casing through which the production fluids enter the well. No particular configuration or method of forming these openings is critical to the invention.
  • the pumping system is located below at least some of the perforations in the casing. Thus, production fluids entering those perforations that are above the pumping system flow in fluid contact past the exterior portions of the electrical motor and into the production fluid intakes, by force of gravity and/or the action of the pumping system.
  • the pumping system should be below enough of the perforations that sufficient production fluids pass the exterior of the electrical motor to provide a cooling effect.
  • at least half of the production fluids will pass by the exterior of the motor before entering the production fluid intakes.
  • the pumping system is below substantially all of the perforations, and substantially the entire volume of production fluids passes in fluid contact with the exterior of the motor. This tends to maximize the desired cooling effect. Having the pumping system below substantially all of the perforations also facilitates separation of gaseous and hquid production fluids before the liquids enter the pumping system. This will increase the production rate when the well produces a mixture of gasses and liquids.
  • gasses circumvent the pump avoids various associated problems such as gas-lock or pumping inefficiencies that are attributable to entrained gasses. As gasses have lower heat capacities than ⁇ quids, having the gasses circumvent the motor in this manner further improves heat transfer and, thus, motor cooling. Additionally, because the pumping unit does not require oversized equipment or a gas separator as are typically used in conventional systems installed above the perforations, no significant additional power is consumed.
  • the pumping system includes an electrical motor and a submergible pump that is driven by the electrical motor.
  • the motor and pump may have a unitary structure (i.e., share a common housing), but it is often preferred that they are separate units which are connected together directly or indirectly as they are installed in the well.
  • FIG 2 Two embodiments of the process of the invention are illustrated in Figure 2.
  • well casing 210 extends along the periphery of well 201, which as shown has been bored through a producing subterranean rock stratum 440 and into a lower, non-producing subterranean rock stratum 441.
  • Producing stratum 440 contains production fluids that are to be pumped to the well head.
  • Casing 210 includes perforations 211 through which the production fluids are admitted into the well for pumping to the surface.
  • a pumping system that includes motor 220 and pump 230. Both motor 220 and pump 230 are located below perforations 211.
  • Motor 220 is affixed to production pipe 250, which is shown in section. If desired, production pipe 250 can take the form of a cofled tube.
  • Motor 220 is shown in section to reveal hollow rotor shaft 221, which rotates when motor 220 is operated to provide motive force to operate pump 230.
  • the production fluids pass through the hollow rotor shaft on their way to the wellhead through production pipe 250.
  • Hollow rotor shaft 221 is mechanically connected, directly or indirectly, to pump 230 in a manner such that pump 230 is operated when hollow rotor shaft 221 is rotated.
  • the drive shaft of pump 230 is directly connected to hollow rotor shaft 221, without intermediate apparatus.
  • it may be desirable to include various types of intermediate apparatus such as a sea ⁇ ng section between motor 220 and pump 230.
  • the manner through which motor 220 is affixed to production pipe 250 and pump 230 is not critical; a variety of fasteners, interlocking devices and the like can be used.
  • Power is provided to the motor from the wellhead through a cable or sim ⁇ ar device, which is not shown.
  • Intake 260 is attached to pump 230.
  • hollow rotor shaft 221 rotates substantially along its longitudinal axis, driving the action of pump 230.
  • Production fluids enter the pumping system through intake 260 and enter pump 230.
  • Hollow rotor shaft 221 is in ⁇ quid communication with production pipe 250 and pump 230, so that fluids pumped upwardly by pump 230 pass through hollow rotor shaft 221 and then enter production pipe 250 through which they are delivered to the wellhead.
  • motor 220 is below perforations 211, production fluids that enter weU 201 flow in fluid contact past the exterior of motor 220 before entering intake 260. This can be due to simple gravity, the pumping action of pump 230, or some combination of these. Arrows 290 indicate the direction of flow of the production fluids. As the production fluids must flow between well casing 210 and motor 220 as they travel toward the intake, the motor is somewhat smaller than the diameter of well casing 210, creating an annulus through which the production fluids can move. As the production fluids move in fluid contact past the exterior portion of motor 220, they remove waste heat and thus provide coo ⁇ ng.
  • FIG. 2 is a so-caUed "inverted" pumping system in which the motor is above the pump. Although this is preferred to have the motor above the pump, it is not critical to the invention, and Figure 2A illustrates an embodiment in which the motor is below the pump.
  • well 201 A has casing 210A.
  • the pumping system includes production pipe 250A, pump 230A, motor 220A and intake 260A.
  • Motor 220A includes hollow rotor shaft 221 A through which production fluids pass.
  • hollow rotor shaft 221A is in mechanical communication with pump 230A so that as motor 220A operates, hoUow rotor shaft 221A causes pump 230A to operate and pump the production fluids through hollow rotor shaft 221A and then into production pipe 250A and up to the weUhead.
  • production fluids enter the weU through perforations 211A, travel past the exterior of motor 220A, enter intake 260A, travel upwardly through ho ⁇ ow rotor shaft 221A and into pump 230A and then through production pipe 250A to the weUhead.
  • Motor 220A is cooled twice by the production fluids; once as they pass in fluid contact with the exterior of motor 220A and again as they pass through ho ⁇ ow rotor shaft 221A in motor 220A).
  • a pumping system including electrical motor 402 and pump
  • Fluid intakes 420 are located below electrical motor 402 below packer 414. In the embodiment shown, fluid intakes 420 lead directly into pump 411, which is located below electrical motor 402. However, it is possible to employ multiple pumps and multiple motors in the submergible pumping system, provided that the intakes are located below at least one electrical motor with a hoUow rotor shaft.
  • hoUow rotor shaft 403 of electrical motor 402 rotates about its longitudinal axis when electrical motor 402 is operated. This is conveniently achieved by affixing stationary magnets 404 to hoUow rotor shaft 403 and supplying stators 405 to exterior housing 410 of electrical motor 402.
  • HoUow rotor shaft 403 is coupled directly or indirectly to drive shaft 412 of pump 411, so that drive shaft 412 rotates when hoUow rotor shaft 403 rotates, thereby supplying mechanical energy to pump 411.
  • ImpeUers 413 are affixed to drive shaft 412 which provides motive force to impeUer 413 when shaft 412 is rotated.
  • Thrust bearing and seal 416 connects electrical motor 402 with pump 411 and provides a seal against leakage of production fluids.
  • Packer 414 assists in supporting the weight of the pumping system and prevents pressurized fluids from the pump from flowing downwardly to the pump intake.
  • Intakes 420 are in fluid communication with hoUow rotor shaft 403 of electrical motor 402.
  • fluids entering intakes 420 flow through pump 411 in the general d ⁇ ection indicated by arrows 408.
  • a first portion of the fluids flow in the general direction indicated by arrows 406, entering hoUow rotor shaft 403 through openings 4 1 and flowing upwardly through hoUow rotor shaft 403 and up to the weUhead.
  • a second portion of the fluids flow in the general c ⁇ rection indicated by arrows 407, passing outwardly through pump housing 409 via openings 417, and then upwardly in a space between weU casing 401 and exterior housing 410 of electrical motor 402.
  • the embodiment shown in Figure 4 permits the electrical motor to be cooled by the production fluids both internaUy (i.e., as the fluids pass through the hoUow rotor shaft) and externaUy (i.e., as the fluids pass between the exterior of the electrical motor and the weU casing), without the need to use a shroud, fluid recirculation or locate the pumping system below the perforations in the weU. This avoids having to drill the weU down below the perforations, i.e., no "rathole” is required to achieve the benefits of this aspect of the invention.
  • This embodiment also permits one to avoid exposing the pumping system to sandy conditions as often exist below the perforations.
  • a pumping system includes electrical motor 502 and pump 511. These are located in a weU having casing 501 with perforations 515. As shown, perforations 515 are located above pump intakes 517, as is preferred, but the perforations may be located at the level of or below pump intakes 517.
  • Electrical motor 502 contains hoUow rotor shaft 503. In the preferred embodiment shown, motor 502 includes a drive system including magnets 504 located about hoUow rotor shaft 503 and stators 505 which are located on the interior of housing 510. When operated, hoUow rotor shaft 503 rotates about its longitudinal axis.
  • Pump 511 includes hoUow drive shaft 512 that is in fluid communication with hoUow rotor shaft 503 of motor 502. When hoUow rotor shaft 503 rotates about its longitudinal axis as electrical motor 502 operates, hoUow drive shaft 512 of pump 511 likewise rotates about its own longitudinal axis.
  • HoUow drive shaft 512 includes exterior (to the shaft) impeUers 513 that pump the production fluids when the pumping system is operated.
  • HoUow drive shaft 512 includes shaft inlet 522, through which fluids enter as the pumping system is operated.
  • Pump 511 includes housing 509 having fluid intakes 517. Fluid intakes 517 are located above shaft inlet 522 and below perforations 515.
  • production fluids enter the weU through perforations 515, flow downwardly past the exterior of electrical motor housing 510 and into intakes 517.
  • the fluids are then pumped downwardly in pump 511 by impeUers 513, where they enter shaft inlet 522 and are pumped upwardly through hoUow drive shaft 512 of pump 511 and then through hoUow rotor shaft 503 of motor 502, aU in the direction indicated by arrows 506.
  • the embodiment shown in Figure 5 includes preferred thrust bearing and seal 516.
  • the downward flow of the fluids through pump 511 before entering shaft inlet 522 reduces the downward force produced on pump 511.
  • this aspect of the invention permits the electrical motor to be cooled both on its exterior and its interior by the production fluids.
  • a pumping system including pump 611 and electrical motor 602 is located in a weU having casing 601 with perforations 615, where production fluids enter the weU. Perforations 615 are located below the pumping system.
  • the production fluids are a mixture of at least one Uquid and at least one gas.
  • intake 620 is located below the rest of the pumping system, although it is possible that one or more pumps or electrical motors can be located below the intakes.
  • Intake 620 has diameter D, which is smaUer than the diameter D' of electrical motor 602 (and, as shown, pump 611) which is immediately above intake 620.
  • Electrical motor 609 includes hoUow rotor shaft 603.
  • motor 602 includes a drive system including magnets 604 located about hoUow rotor shaft 603 and stators 605 which are located on the lterior of housing 610.
  • hoUow rotor shaft 603 rotates about its longitudinal axis.
  • HoUow rotor shaft 603 is in fluid communication with intake
  • motor 602 is directly above intake 620, and hoUow rotor shaft 603 communicates directly with intake 620.
  • one or more pumps can be located between motor 602 and intake 620, provided that hoUow rotor shaft 603 is in fluid communication with intake 620 ind ⁇ ectly through the intervening pump.
  • a mixture of gaseous and Uquid fluids enters the weU through perforations 615. These move upwardly in the direction indicated by arrows 606 into vortex zones indicated in Figure 6 by reference numerals 622.
  • Vortex zones 622 are created in part by v ⁇ tue of the diameter of intake 620 being smaUer than that of electrical motor 602.
  • Uquids and gasses separate efficiently. Gasses move upwardly in the direction indicated by arrows 608 between casing 602 and the exterior housings 610 and 609 of electrical motor 602 and pump 611. Liquids enter intake 620, flow downwardly through a section of intake 620, then enter hoUow rotor shaft 603, and then are pumped upwardly to the weUhead. Arrows 607 in Figure 6 indicate the direction of the Uquids.
  • the pumping system may contain additional elements as may be necessary or des ⁇ able in any particular app ⁇ cation.
  • seal chamber sections are often provided in pumping systems for deep hole weUs. Such seal sections may also carry pump thrust and can perform additional functions as weU, as described by Brookbank in "Inverted Pump Systems Design and App ⁇ cations", ESP Workshop, Houston, AprU 26-28, 2000. As described by Brookbank, the functions performed by the seal chamber section can be divided among several pieces of apparatus if des ⁇ ed.
  • a seal chamber section or other device for carrying pump thrust is preferably part of the pumping system.
  • apparatus such as sand sk ⁇ ts, packers, various types of connectors and the like can be incorporated into the pumping system or used in conjunction with the pumping system.
  • the pumping system may contain anti- cavitation devices like a primer pump to prevent cavitation of the fluid in the hoUow rotor shaft or pump. These may be especiaUy useful in configurations where the pump is above the motor.
  • the motor, pump, intakes, seal sections and other apparatus may be constructed as two or more separate sections that are connected together to form the overaU pumping system.
  • a wide variety of electrical motor designs can be used in the pumping system of the invention, provided that the motor contains a hoUow rotor shaft through which the production fluids can flow to provide cooUng and/or vortex generators in the annulus between the motor and the weU casing or shroud.
  • Induction motors and brushless DC motors are useful, among others. Suitable motors of that type are described in U. S. Patent Nos.
  • the motor can be any submergible electric motor having a longitudinal, rotating rotor shaft, in which the rotor shaft has a longitudinal bore.
  • Conventional electric motors having a longitudinal rotor shaft in some cases can be retrofitted for use in this invention simply by boring out the rotor shaft to form the hoUow rotor shaft.
  • the motor may be a single piece or a tandem configuration. Multiple motors can be used and, if des ⁇ ed, pumps can be placed both above and below the motor. Seal sections and other components may be instaUed between the motor and pump.
  • the motor As the motor wUl be submerged in the production fluids, it is preferably adapted to operate in those conditions.
  • the motor preferably will contain a motor fluid that provides lubrication but more importantly retards the entrainment of production fluids in the motor.
  • the motor fluid may also contain various weU- treating materials such as scale inhibitors, emulsifiers, anti-emulsion agents, surfactants, water, and the like.
  • various types of seals can be incorporated into the motor to retard the leakage of production fluids into it, and as mentioned above, seal chamber sections can be used to accommodate thermal expansion of the motor fluid and help equaUze pressure between the inside and outside of the motor.
  • the motor fluid is at a positive pressure relative to the hoUow rotor shaft of the motor and has leaking seals, so that motor fluid slowly leaks from the motor into the production fluid.
  • a source of fresh motor fluid is provided, either from a reservo ⁇ in the pumping system or through a tube or capiUary system from the weUhead.
  • a pressure independent modulating flow control valve such as a SkoFloTM or SubSeaTM valve is suitable for maintaining a suitable positive pressure and flow of fresh lubrication fluid into the motor.
  • a particularly preferred motor has vortex generators on its exterior surface, or else is enclosed within a shroud that has vortex generators on its interior surface.
  • the vortex generators operate to generate streamwise vortices in the production fluids as they pass the exterior of the motor.
  • the vortex generators are preferably static devices having geometry and dimensions such that when the production fluids flow through and past the generators, a swirl in the flow is imparted. These streamwise vortices greatly improve heat transfer from the exterior of the motor to the production fluids, even further increasing the benefits of this invention.
  • FIG. 3 An example of a motor containing vortex generators is schematicaUy Ulustrated in Figure 3.
  • WeU 300 has casing 310 and perforations 311. The internal diameter of weU 300 is D.
  • Motor 320 and pump 330, each having a diameter d, are disposed in the weU.
  • Motor 320 is affixed to production pipe 350, which extends to the weUhead.
  • HoUow rotor shaft 321 connects motor 320 and pump 330, in the same manner as described with respect to Figure 2.
  • Pump 330 includes intake 360, where production fluids enter the pumping system.
  • production fluids enter the weU at perforations 311, flow past the exterior of motor 320, into intake 360, through pump 330, through hoUow rotor shaft 321 in motor 320 and up through production pipe 350 to the weU head, as indicated by arrows 390.
  • the exterior surface of motor 320 has vortex generators.
  • An alternative arrangement would be to surround motor 320 in a shroud that has vortex generators on its interior surface.
  • the vortex generators take the form of a pluraUty of fins 366. Fins 3,66 are s ⁇ ghtly offset to the direction of flow of the production fluids, and adjacent fins 366 are offset in opposite directions. Thus, each pair of fins 366 define a gap which narrows in the direction of flow. The dimensions of fins 366 and the offset angle are sufficient to create streamwise vortices in the production fluids as they flow past the fins.
  • Suitable offset angles are typicaUy +/- 10-30, preferably 10-20 degrees from the d ⁇ ection of flow of the production fluids.
  • Suitable dimensions for fins 366 are iUustrated in Figure 3A.
  • the gap between motor 320 and weU casing 311 is defined by (D-d)/2, where D and d are as described above.
  • a suitable fin 366 wUl extend outwardly from the exterior of motor 320 (or inwardly from the exterior surface of a surrounding shroud) approximately 1/3-3/4 of the width of the gap between the motor and weU casing or, when a shroud is used, between the motor and interior surface of the shroud; in Figure 3A an especiaUy preferred dimension of v., the gap width is iUustrated.
  • numeral 325 designates either the exterior surface of the motor or the internal surface of a surrounding shroud.
  • fin 366 is preferably beveled with increasing width in the d ⁇ ection of flow, reaching its maximum width at a point approximately 1/3-3/4 down its length.
  • leading edge 399 can take other shapes, including those shown in out ⁇ ne in Figure 3A.
  • OveraU length is preferably about 1 to about 4, more preferably about 1.5 to about 3 tunes the width of the gap. In Figure 3A, the length is shown as equal to the gap width.
  • two rows of fins 366 are used.
  • a single row can be used, or greater than two rows can be used.
  • a preferred spacing between the rows is about 10-30 times the gap distance. However, the spacing may be adjusted to trade off pressure loss with heat transfer.
  • Other suitable vortex generator designs can be used, such as are described, for example, by Pau ⁇ e and Eaton, Report #MD51, August 1988, "The Fluid Dynamics and Heat Transfer Effect of Streamwise Vortices Embedded in a Turbulent Boundary Layer".
  • the pump itself has no special design reqmrements, other than it is adapted to pump production fluids through the hoUow rotor shaft of the motor.
  • the particulars of the pump design wiU be selected to fit the particular app ⁇ cation.
  • the pump is in Uquid communication with the hoUow rotor shaft of the motor. This is accomp ⁇ shed by buUding the pump and motor as a single unit or incorporating the pump into the motor, as described in U. S. Patent Nos.
  • Pumps of the type conventionaUy used in ESPs are entirely suitable, and can easUy be adapted for use in this invention through the design of the connection between the pump outlet (or inlet) and the motor.
  • Progressive cavity pumps are also preferred types.
  • the pump may be one piece or in tandem sections. Multiple pumps may be used. If desired, separate pumps can be provided above and below the motor.
  • the method of this invention is useful in a variety of weUs, including water, o ⁇ and natural gas weUs.
  • the pumping method is particularly advantageous in weUs where, using a conventional ESP, any flow of production fluids through the annulus between the motor housing and the weU casing would be expected to be laminar.
  • WeUs of this type include those having weU conditions such as high viscosity production fluids, the formation of emulsions, low flow rates, multiphase flows, deviated and horizontal weUs and large motor and/or weU diameters, especiaUy in the o ⁇ industry.
  • the weU operator can take advantage of the enhanced heat transfer and unproved coo ⁇ ng of the motor in several ways.
  • the motor will be more efficiently cooled, and the operating temperature wiU be lower.
  • the operator may choose to take advantage of this lower operating temperature to prolong the motor life.
  • the lower temperature also tends to reduce electrical resistance, thus aUowing equivalent work to be done with less power consumption.
  • the operator may elect to increase the power to the motor so that it runs at higher temperatures sim ⁇ ar to those that would be experienced in prior art processes. In this case, the operator chooses to forego longer motor Ufe in return for higher production rates that are achieved because of the additional power that is used.
  • Turbulent flow can be expressed in terms of Reynolds number (a dimensionless parameter), which is a function of the average fluid velocity, kinematic viscosity of the fluid and diameter of the hoUow rotor shaft.
  • Reynolds number a dimensionless parameter
  • a Reynolds number of about 2300 or higher is typicaUy indicative of turbulent flow.
  • flow conditions of the production fluids through the hoUow rotor shaft of the motor is such that the Reynolds number is at least about 3000.
  • a Reynolds number in excess of 5000 to 10000 is more preferred.
  • Nusselt number is a dimensionless measure of heat transfer.
  • the Nusselt number is a function of the Reynolds number, the Prantl number, and the absolute viscosity of the bulk fluid and fluid at the waU.
  • a high Nusselt number (exceeding 10) represents a high heat transfer rate for a given temperature difference.
  • low Nusselt numbers (below 5) are indicative of poor convective heat transfer.
  • Enhanced heat transfer from the motor to the production fluid can be expected when the Nusselt number is at least 10, preferably at least 50, and the method of the invention is preferably operated under conditions that achieve such Nusselt numbers.
  • Operating conditions preferably are also chosen so as to provide a Brinkmann number (another dimensionless parameter) of less than 2, preferably less than 0.5.
  • the Brinkmann number indicates the direction of heat transfer within a viscous fluid. It is a function of the average velocity of the fluid, its absolute viscosity, the thermal conductivity of the fluid and the temperature difference between the fluid and the inside waU of the hoUow rotor shaft.
  • heat wiU travel from the hot motor to the cooler production fluid and fluid friction wiU not add additional heat to the motor. Viscous dissipation effects are neg ⁇ gible, when the Brinkmann number is less than 0.5.
  • the hoUow rotor shaft is the drive shaft of the motor, operating conditions can be further described with reference to a Rossby number (still another dimensionless parameter).
  • the Rossby number provides an indication as to whether spinning flow wiU or wiU not dominate axial flow in the hoUow rotor shaft.
  • Conditions generating a Rossby number of at least about 0.5, preferably at least about 1.0 are preferred.
  • the Rossby number is a function of average fluid velocity, fluid angular velocity and the inside diameter of the hoUow rotor shaft.
  • Yet another advantage of this invention is that it permits gaseous production fluids to separate from Uquids before entering the pumping system.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

Selon la présente invention, le taux de production, la durée de vie utile ainsi que l'efficacité du fonctionnement de systèmes de pompage submersible électrique sont renforcés lorsque le système fonctionne de manière que le moteur (220, 320) soit refroidit par deux passages de fluides de production. Les fluides de production suppriment la chaleur perdue du moteur (220, 230) en passant au contact de l'extérieur du moteur (220, 230), de même qu'en passant par l'arbre (221) du rotor creux du moteur (220, 320). Ce refroidissement renforcé permet au moteur de fonctionner à une température plus basse, ce qui lui permet d'avoir une durée de vie ainsi qu'une efficacité accrues, et/ou de fonctionner à une puissance supérieure sans entraîner de variation de température. En outre, un matériel surdimensionné et en excès n'est pas nécessaire à l'utilisateur, ce qui lui permet d'obtenir un système encore plus performant et plus économique. Dans une autre variante, l'invention se rapporte à un procédé de pompage de fluides faisant appel à un moteur pourvu de générateurs vortex (366) disposés sur ses surfaces extérieures, ou sur les surfaces intérieures d'une enveloppe concentrique.
EP02709817A 2001-03-12 2002-03-11 Procede de pompage de fluides Withdrawn EP1379756A4 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US27567701P 2001-03-12 2001-03-12
US275677P 2001-03-12
US838744 2001-04-19
US09/838,744 US20020153141A1 (en) 2001-04-19 2001-04-19 Method for pumping fluids
PCT/US2002/007348 WO2002072998A1 (fr) 2001-03-12 2002-03-11 Procede de pompage de fluides

Publications (2)

Publication Number Publication Date
EP1379756A1 true EP1379756A1 (fr) 2004-01-14
EP1379756A4 EP1379756A4 (fr) 2005-09-14

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WO (1) WO2002072998A1 (fr)

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US8118089B2 (en) * 2009-06-19 2012-02-21 Harrier Technologies, Inc. Down hole delivery system
WO2013070235A1 (fr) * 2011-11-11 2013-05-16 Halliburton Energy Services, Inc. Ensemble de régulation autonome de fluide comprenant un sélecteur commandé par densité pour diriger l'écoulement de fluide dans un système de régulation de fluide
CN104769216B (zh) * 2012-04-02 2017-05-31 沙特阿拉伯石油公司 用于分离气体和油的电动潜水泵组件
GB2507506B (en) * 2012-10-31 2015-06-10 Hivis Pumps As Method of pumping hydrocarbons
US9356551B2 (en) * 2013-01-31 2016-05-31 GM Global Technology Operations LLC Method and apparatus for controlling an electric motor employed to power a fluidic pump
WO2014209960A2 (fr) * 2013-06-24 2014-12-31 Saudi Arabian Oil Company Pompe et compresseur intégrés et procédé de production de fluide de puits polyphasique en fond de trou et à la surface
US10309381B2 (en) * 2013-12-23 2019-06-04 Baker Hughes, A Ge Company, Llc Downhole motor driven reciprocating well pump
CN105242014A (zh) * 2015-10-22 2016-01-13 中国石油天然气股份有限公司 井下气液模拟检测系统
CN111102209B (zh) * 2019-12-26 2021-06-04 东北石油大学 一种应用于低产井的电潜泵回流举升装置及回流举升方法
US11371326B2 (en) 2020-06-01 2022-06-28 Saudi Arabian Oil Company Downhole pump with switched reluctance motor
US11499563B2 (en) 2020-08-24 2022-11-15 Saudi Arabian Oil Company Self-balancing thrust disk
US11920469B2 (en) 2020-09-08 2024-03-05 Saudi Arabian Oil Company Determining fluid parameters
US11644351B2 (en) 2021-03-19 2023-05-09 Saudi Arabian Oil Company Multiphase flow and salinity meter with dual opposite handed helical resonators
US11591899B2 (en) 2021-04-05 2023-02-28 Saudi Arabian Oil Company Wellbore density meter using a rotor and diffuser
US11913464B2 (en) 2021-04-15 2024-02-27 Saudi Arabian Oil Company Lubricating an electric submersible pump
US11821430B2 (en) 2021-11-17 2023-11-21 Halliburton Energy Services, Inc. Oil transport structure in an electric motor of an electric submersible pump (ESP) assembly
US11994016B2 (en) 2021-12-09 2024-05-28 Saudi Arabian Oil Company Downhole phase separation in deviated wells

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Also Published As

Publication number Publication date
CN1281847C (zh) 2006-10-25
CN1507531A (zh) 2004-06-23
EP1379756A4 (fr) 2005-09-14
WO2002072998A1 (fr) 2002-09-19

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