PROGRESSIVE CAVITY PUMP
An electric submersible progressing cavity pump (ESPCP) assembly that restricts reverse rotation of the pump motor and provides for efficient motor shutdown in the event of reverse rotation is disclosed. When the ESPCP rotates in a reverse direction, components associated with the rotating motor shaft stop rotation of the shaft to increase the torque and current of the motor, and the increased torque/current on the motor actuates a torque or current limit switch to shut off the motor. Also, particle and gas separation mechanisms are disclosed, which separate particulates and gas from the fluid flowing into the pump so that the fluid that reaches the rotor and stator assembly has a higher proportion of liquid than the resident well fluid.
This application claims priority from U.S. Provisional Patent Application Ser. No. 61/691,426, filed Aug. 21, 2012, and U.S. Provisional Patent Application Ser. No. 61/783,263, filed Mar. 14, 2013, the disclosures of which are hereby expressly incorporated by reference herein in their entirety.
BACKGROUND OF THE INVENTION1. Field of the Disclosure
The present disclosure relates generally to systems and methods associated with progressing cavity pumps and, in particular, to systems and methods associated with electric submersible progressing cavity pumps (“ESPCP”).
2. Description of the Related Art
An ESPCP includes a rotor and stator for pressurizing fluid. In one known well arrangement, an ESPCP is positioned in an interior of a well to pump fluid from the well towards the surface. Rotation of the rotor is driven by an electric motor submerged in fluid below the rotor and stator. A shaft allowing for eccentricity connects the electric motor to the rotor. The ESPCP includes a check valve that restricts fluid from flowing through the ESPCP in a reverse direction. If the electric motor is started in a reverse direction, the check valve will prevent downstream fluid from entering the ESPCP, which may cause rapid heating of the rotor and stator.
Also, in many well arrangements which include an ESPCP, pumped fluids may include entrained particles, such as sand, as well as gas in the form of bubbles. Problematically, entrained particles and gas bubbles can prevent optimum operation of the ESPCP.
What is needed is an improvement over the foregoing.
SUMMARYThe present disclosure provides an electric submersible progressing cavity pump (ESPCP) assembly that restricts reverse rotation of the pump motor and provides for efficient motor shutdown in the event of reverse rotation. In particular, when the ESPCP rotates in a reverse direction, components associated with the rotating motor shaft stop rotation of the shaft to increase the torque and current of the motor, and the increased torque/current on the motor actuates a torque or current limit switch to shut off the motor. Also, particle and gas separation mechanisms are provided, which separate particulates and gas from the fluid flowing into the pump so that the fluid that reaches the rotor and stator assembly has a higher proportion of liquid than the resident well fluid.
In one illustrative embodiment, an electric submersible progressing cavity pump assembly includes a motor having a shaft defining a longitudinal axis, the shaft rotatable in a forward direction and in a reverse direction; a coupling rotatably fixed to the shaft; a collar releasably coupled with said coupling, the collar movable along the longitudinal axis; a bracket attached to the motor and at least partially surrounding said collar, the bracket comprising at least one stationary stop; the collar positionable in a first position adjacent the coupling when the shaft is rotated in the forward direction; and the collar displaceable from the coupling along the longitudinal axis to a second position in which the collar contacts the at least one stationary stop when the shaft is rotated in the reverse direction.
In another illustrative embodiment, an electric submersible progressing cavity pump assembly for pumping a fluid having entrained particulates includes a motor having a rotatable shaft defining a longitudinal axis; a pump mechanism driven by the shaft to pump the fluid; a shell disposed intermediate the motor and the pump assembly, the shell including at least one slot; and an inducer at least partially disposed within the shell, the inducer driven by the shaft for rotation about the longitudinal axis, the inducer operable to centrifugally urge particulates in the fluid outwardly from the shell through the at least one slot.
In another illustrative embodiment, an electric submersible progressing cavity pump assembly for pumping a fluid having entrained gas bubbles includes a motor having a rotatable shaft defining a longitudinal axis; a pump mechanism driven by the shaft to pump the fluid; a shell disposed intermediate the motor and the pump assembly and comprising at least one hole; and a gas separator at least partially disposed within the shell, the gas separator operable to channel entrained gas bubbles in the fluid outwardly from the shell through the at least one hole.
It should be understood that the components that stop rotation of the shaft to actuate a limit switch to shut off the motor, the particle separation mechanisms that separate particulates from the fluid, and the gas separation mechanisms that separate gas from the fluid may be employed in pump devices individually, or the foregoing devices may be combined, including any two of the features or all three features, into the same device.
Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived.
The above mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of various features and components according to the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present disclosure. The exemplification set out herein illustrates embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
DETAILED DESCRIPTION A. IntroductionFor the purposes of promoting and understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, which are described below. The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise form disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. It will be understood that no limitation of the scope of the invention is thereby intended. The invention includes any alterations and further modifications in the illustrated devices and described methods and further applications of the principles of the invention which would normally occur to one skilled in the art to which the invention relates.
Referring to
Rotation of rotor 20 within stator 22 is powered by electric motor 24. In one embodiment, electric motor 24 is a submersible electric motor configured to be submerged in fluid below progressing cavity pump 18 when ESPCP 12 is positioned in well 14. Electric motor 24 may be, for example, a Franklin Electric CBM plus motor model #23472935256. ESPCP 12 may include a motor lead (not shown) providing electric power and control signals to electric motor 24 from the surface of the well installation. The shaft of electric motor 24 is connected to rotor 20 through flex shaft 26. Extension 28 surrounds flex shaft 26 between electric motor 24 and progressing cavity pump 18. In the embodiment illustrated in
In one embodiment, progressing cavity pump 18 may include a check valve (not shown) at one end. The check valve restricts fluid from flowing through progressing cavity pump 18 in a reverse direction. If electric motor 24 is started in a reverse direction, the check valve will prevent downstream fluid from entering progressing cavity pump 18. Additionally, fluid passing fluid inlets 30 will not be drawn into progressing cavity pump 18 if rotor 20 rotates in a reverse direction. With no fluid in progressing cavity pump 18, reverse rotation of rotor 20 may cause rapid heating of rotor 20 and stator 22. In one embodiment, rapid heating of the rubber forming stator 22 may quickly lead to catastrophic failure. The exemplary backstop elements of the present disclosure restrict electric motor 24 and progressing cavity pump 18 from rotating in a reverse direction, thereby restricting the potential for motor failure.
Electric motor 24 is attached to extension 28 through motor bracket 32. The exterior of electric motor 24 is stationary relative to attached motor bracket 32, the exterior of extension 28, and stator 22. Motor shaft 34 and coupling 36 transmit rotational energy from electric motor 24 to flex shaft 26 and rotor 20.
B. Backstop MechanismsReferring next to
Referring back to
In one embodiment, collar 40 includes an upper portion having a first diameter including upper ramp surfaces 60 with upper projections 54 and a lower portion having a second diameter including ramp surfaces 48 and lower projections 52. In the embodiment illustrated in
In the embodiment illustrated in
Referring next to
In the embodiment illustrated in
In one exemplary embodiment, ramp surfaces 48, 58 have a helical pitch of about 2 inches. In one exemplary embodiment, collar 40 has a shape that flares outwardly from bottom to top and ramp surface 58 has a ramp angle with a horizontal plane orthogonal to an axis aligned with motor shaft 34. In the embodiment illustrated in
Referring again to the embodiment illustrated in
As illustrated in
In one embodiment, electric motor 24 includes a torque limit or torque detection switch. The torque limit switch monitors the torque necessary for electric motor 24 to rotate motor shaft 34 and stops electric motor 24 from applying further torque to motor shaft 34 if the torque limit switch determines that the monitored torque exceeds a predetermined torque limit. In one embodiment, once the torque generated by electric motor 24 does not exceed the predetermined torque limit, the torque limit switch is reset and electric motor 24 can again attempt to rotate motor shaft 34. In one embodiment, the torque limit switch is a physical switch (not shown). Exceeding the predetermined torque limit results in a mechanical action stopping electric motor 24. In another embodiment, the torque limit switch controls the current to the motor. In this embodiment, exceeding a predetermined current results in the torque limit switch turning off electric motor 24.
In another embodiment, illustrated in
Referring again to
An exemplary processing sequence 110 for switch 100 is illustrated in
In the embodiment illustrated in
Backstop mechanisms including various coupling-collar combinations can be constructed. Referring next to
As illustrated in
In one embodiment, as electric motor 24 rotates coupling 36A in a forward direction, ramp surfaces 46A of coupling 36A and ramp surfaces 48A of collar 40A cooperate such that collar 40A rotates with coupling 36A in the forward direction. During rotation in the forward direction, upper projections 54A are positioned below stationary stops 42 and do not engage stationary stops 42.
In this illustrated embodiment, when electric motor 24 rotates coupling 36A in reverse direction 56, ramp surface 46A of coupling 36A engages ramp surface 48A of collar 40A. The force of ramp surface 46A against ramp surface 48A in reverse direction 56 causes collar 40A to axially displace relative to coupling 36A and begin to rotate collar 40A in reverse direction 56. Rotating collar 40A in reverse direction 56 causes collar 40A to be forced upwardly and away from coupling 36A along the axis of motor shaft 34 until upper projections 54A of collar 40A engage the stationary stop elements 42. Once upper projections 54A engage the stationary stop elements 42, collar 40A transmits a force through ramp surfaces 48A to coupling 36A through adjacent ramp surfaces 46A, resisting the further rotation of coupling 36A. Because coupling 36A is attached to motor shaft 34, this force is further transmitted to motor shaft 34 and electric motor 24. Thus, in the illustrated embodiment, rotation of electric motor 24 in reverse direction 56 will cause collar 40A to engage stationary stop elements 42 and stop movement of motor shaft 34. In one embodiment, a torque limit switch stops electric motor 24 from applying torque to attempt to rotate motor shaft 34.
Referring now to
Additionally, during rotation in the forward direction, a downforce F1 is exerted on the top surfaces of vanes 80B as the top surfaces of vanes 80B are angled such that each vane 80B resistingly confronts the fluid as vanes 80B are rotated. This downforce helps maintain the engagement between coupling 36B and collar 40B by preventing axial displacement of collar 40B away from coupling 36B and advantageously provides additional pumping force to the fluid flowing through the pump. In this manner, because axial displacement of collar 40B from coupling 36B is prevented, vanes 80B rotate and pass underneath stationary stops 42B formed along the interior of bracket 32B.
This axial displacement of collar 40B from coupling 36B effects the stoppage of electric motor 24 in the manner described above. Additionally, as collar 40B is urged in the reverse direction, portion 52B begins to separate from portion 50B due to the inertia of collar 40B to expose portion 52B. Fluid force F3 acts on exposed portion 52B to urge ramp surface 48B upward along ramp surface 46B so that collar 40B rises. Further, as coupling 36B rotates in the reverse direction, vanes 80B contribute to the axial displacement of collar 40B because, as previously described, collar 40B is urged in the reverse direction and the bottom surface of each vane 80B faces and pushes against the fluid. Because each vane 80B is angled as shown, this pushing causes lift F2 on that bottom surface of each vane 80B to assist with the axial displacement of collar 40B relative to coupling 36B. These two fluid forces F3 and F2 combine to effect the axial displacement of collar 40B from coupling 36B so that vanes 80B can engage stationary stops 42B. As previously described in further detail for other embodiments, when vanes 80B strike stationary stops 42B, the stoppage of the reverse rotation increases the torque on motor shaft 34 that actuates a torque limit switch to shut off electric motor 24.
Advantageously, since assembly and replacement of parts for ESPCP 12 can require installing parts of various sizes, abbreviated vanes 80B allow for the use of modified bracket 32B having minimized stationary stops 42B, as shown in
Referring to
First, referring to
Particulates are expelled from the fluid through particulate slots 204 by rotation of inducer 216, which centrifugally forces particulates radially outwardly. As the fluid, containing entrained particulates, travels the length of inducer 216 along rotating helical thread 220, the relatively heavier particulates in the fluid are centrifugally forced outwardly and are expelled through particulate slots 204 concurrently with the intake of some fluid into slots 204. Further, to prevent redeposition of particulates through one particulate slot 204 that have already been expelled through another particulate slot 204, particulate slots 204 are spirally staggered in a spaced manner along the length of bottom shell 200.
Second, still referring to
Referring to
Referring to
As fluid with entrained gas bubbles is pumped up and along the length of inducer 216 and into crossover 224, the rotation of inducer 216 will tend to centrifugally force the relatively heavier, liquid-heavy fluid outwardly toward shell 200 while the relatively lighter, gas-heavy fluid will remain inwardly adjacent inducer 216. In other words, the fluid having a greater proportion of liquid to gas bubbles (liquid-heavy portion) is directed radially outwardly and away from inducer 216 while the fluid containing a greater proportion of gas bubbles (gas-heavy portion) remains inwardly close to inducer 216. The liquid-heavy portion flows radially outwardly through lower ports 240 (shown by arrows A4) and thence upwardly through liquid channels 244 that direct fluid upward toward rotor-stator housing 152 and into the pumping mechanism of ESPCP 12. The gas-heavy portion flows upwardly past lower ports 240, remaining substantially within crossover 224, toward gas slinger 232. Gas slinger 232 directs the gas-heavy portion outwardly through upper ports 236 (shown by arrows A3) through gas holes 208 in shell 200. Further, since the area immediately outside of gas holes 208 of shell 200 has a lower pressure than the interior of crossover 224, the gas heavy fluid is further drawn outwardly through gas holes 208.
Referring to
Referring to
As fluid with entrained gas bubbles is pumped up and along the length of inducer 216 and into crossover 228, the rotation of inducer 216 will tend to centrifugally force the liquid-heavy fluid outwardly toward shell 200, while the gas-heavy fluid remains inwardly close to rubber inducer 216. Vertical separation D1 helps channel the liquid-heavy fluid to avoid the interior of axial entry crossover 228 and continue (shown by arrows A4) toward rotor-stator housing 152 along circumferential gaps 248. The gas-heavy portion flows upward toward gas slinger 232. Gas slinger 232 directs the gas-heavy fluid outward through upper ports 236 (shown by arrows A3) and out through gas holes 208. Further, as in crossover 224, since the area immediately outside of gas holes 208 has a lower pressure than the interior of crossover 224, the gas-heavy fluid is further drawn outwardly.
Referring to
While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.
Claims
1. An electric submersible progressing cavity pump assembly comprising:
- a motor having a shaft defining a longitudinal axis, said shaft rotatable in a forward direction and in a reverse direction;
- a coupling rotatably fixed to said shaft;
- a collar releasably coupled with said coupling, said collar movable along said longitudinal axis;
- a bracket attached to said motor and at least partially surrounding said collar, said bracket comprising at least one stationary stop; said collar positionable in a first position adjacent said coupling when said shaft is rotated in said forward direction; and said collar displaceable from said coupling along said longitudinal axis to a second position in which said collar contacts said at least one stationary stop when said shaft is rotated in said reverse direction.
2. The pump assembly of claim 1, further comprising a torque detection switch, said torque detection switch operable to stop said motor when said collar contacts said at least one stationary stop.
3. The pump assembly of claim 1, further comprising a current detection switch, said current detection switch operable to stop said motor when said collar contacts said at least one stationary stop.
4. The pump assembly of claim 1, wherein said coupling and said collar comprise respective surfaces disposed substantially parallel to said longitudinal axis, said surfaces in driving contact with one another with said shaft is rotated in said forward direction and said surfaces spaced from one another when said shaft is rotated in said reverse direction.
5. The pump assembly of claim 1, wherein said collar further comprises at least one ramped surface, said at least one ramped surface contacting said at least one stationary stop when said shaft is rotated in said reverse direction.
6. The pump assembly of claim 1, wherein said collar further comprises an outer circumference and at least one vane situated along said outer circumference, said at least one vane contacting said at least one stationary stop when said shaft is rotated in said reverse direction.
7. The pump assembly of claim 6, wherein said at least one vane is angled such that a first force, urging said collar into said first position, is applied to each said vane when said collar is rotated in said forward direction, and a second force, urging said collar into said second position, is applied to each said vane when said collar is rotated in said reverse direction.
8. The pump assembly of claim 6, comprising a plurality of said vanes, said plurality of vanes defining a plurality of circumferential gaps each disposed between a respective pair of said vanes.
9. The pump assembly of claim 1, wherein said coupling comprises a first ramp surface and said collar comprises an second ramp surface complementary to said first ramp surface, said first and second ramp surfaces sliding with respect to one another to urge said collar into said second position when said shaft is rotated in said reverse direction.
10. The pump assembly of claim 1, wherein said bracket further comprises at least one fluid inlet.
11. An electric submersible progressing cavity pump assembly for pumping a fluid having entrained particulates, comprising:
- a motor having a rotatable shaft defining a longitudinal axis;
- a pump mechanism driven by said shaft to pump the fluid;
- a shell disposed intermediate said motor and said pump assembly, said shell including at least one slot; and
- an inducer at least partially disposed within said shell, said inducer driven by said shaft for rotation about said longitudinal axis, said inducer operable to centrifugally urge particulates in the fluid outwardly from said shell through said at least one slot.
12. The pump assembly of claim 11, wherein said inducer comprises a helical thread.
13. The pump assembly of claim 11, wherein said inducer is formed of a resilient material and overlies said shaft.
14. The pump assembly of claim 11, wherein said shell comprises a plurality of said slots, said slots disposed in a helically staggered, spaced relation with respect to one another along a length of said shell.
15. An electric submersible progressing cavity pump assembly for pumping a fluid having entrained gas bubbles, comprising:
- a motor having a rotatable shaft defining a longitudinal axis;
- a pump mechanism driven by said shaft to pump the fluid;
- a shell disposed intermediate said motor and said pump assembly and comprising at least one hole; and
- a gas separator at least partially disposed within said shell, said gas separator operable to channel entrained gas bubbles in the fluid outwardly from said shell through said at least one hole.
16. The pump assembly of claim 15, wherein said gas separator is a crossover device comprising at least one port, each said port of said crossover aligned with a respective said hole in said shell.
17. The pump assembly of claim 16, wherein said crossover device further comprises a wall disposed with said shell, said wall including at least one port, said port spaced from said shaft and disposed radially adjacent said shell.
18. The pump assembly of claim 17, wherein said crossover device comprises a plurality of said walls having a respective plurality of said ports, and a plurality of circumferentially spaced channels defined between respective pairs of said walls, said channels aligned with respective said ports.
19. The pump assembly of claim 16, wherein said crossover device further comprises a top opening, and a penetrable resilient gas barrier positioned in said top opening.
20. The pump assembly of claim 16, wherein said crossover device further comprises a top opening, said shaft extending through said top opening.
21. The pump assembly of claim 15, wherein said gas separator further comprises a gas slinger rotatable with said shaft.
Type: Application
Filed: Aug 15, 2013
Publication Date: Apr 17, 2014
Inventor: Russell Bookout (Fort Wayne, IN)
Application Number: 13/967,904
International Classification: F04D 13/10 (20060101); F04D 13/06 (20060101);