Surface pump assembly

Abstract

A surface mounted pump assembly includes a centrifugal pump having a plurality of impellers and an electric motor adapted to drive the pump such that a thrust load from the pump is transmitted to the motor.

Claims

1. A method of using a pump assembly, comprising: wherein the pump assembly comprises: a skid; an electric motor mounted on the skid; a pump, comprising: a housing mounted on the skid; an intake chamber connected to the housing; a shaft rotationally coupled to the motor and disposed in the housing; and a plurality of stages, each stage comprising: a mixed axial and radial flow impeller rotationally coupled to the shaft; and a diffuser in fluid communication with the impeller; and wherein each stage is oriented in the same direction; a mechanical seal disposed between the motor and the pump and around the shaft; coupling the shaft and the motor directly rotationally using a coupling disposed between the mechanical seal and the motor; connecting the pump directly to the electric motor without a thrust chamber by connecting the intake chamber of the pump directly to a bell housing of the electric motor, wherein the coupling is disposed in the bell housing; exposing the coupling to atmosphere; and injecting water into a wellbore using the pump located at a surface of the wellbore.

2. The method of claim 1, wherein: the wellbore is an injection wellbore in fluid communication with a formation, and the method further comprises recovering oil from a second wellbore in fluid communication with the formation.

3. The method of claim 1, wherein: the injected water mixes with oil in the wellbore, and the method further comprises recovering the oil and water mixture at the surface.

4. The method of claim 1, further comprising supplying fluid to the pump using the intake chamber.

5. The method of claim 4, further comprising sealing the intake chamber from atmosphere using the mechanical seal.

6. The method of claim 1, further comprising discharging water from the pump using a discharge flange, wherein the discharge flange is connected to the housing at an end distal from the intake chamber.

7. The method of claim 6, further comprising filling the motor with oil, thereby lubricating thrust bearings disposed in the motor, wherein the thrust bearings are angular contact ball bearings.

8. The method of claim 1, wherein the bell housing has a window formed through a wall of the bell housing.

9. The method of claim 1, further comprising transmitting thrust from the shaft to the motor using thrust bearings disposed in the motor, wherein the thrust bearings are angular contact bearings.

10. The method of claim 9, further comprising filling the motor with oil, thereby lubricating the angular contact bearings.

11. A method of using a pump assembly, comprising: wherein the pump assembly comprises: a skid; an electric motor mounted on the skid; a pump, comprising: a housing mounted on the skid; an intake chamber connected to the housing; a shaft rotationally coupled to the motor and disposed in the housing; and a plurality of stages, each stage comprising: a mixed axial and radial flow impeller rotationally coupled to the shaft; and a diffuser in fluid communication with the impeller; and wherein each stage is oriented in the same direction; a mechanical seal disposed between the motor and the pump and around the shaft; coupling the shaft and the motor directly rotationally using a coupling disposed between the mechanical seal and the motor; connecting the pump directly to the electric motor without a thrust chamber by connecting the intake chamber of the pump directly to a bell housing of the electric motor, wherein the coupling is disposed in the bell housing; exposing the coupling to atmosphere; locating the pump at a surface of the wellbore; and operating the pump to inject water into the wellbore or to pump oil from the wellbore into a pipeline.

12. The method of claim 11, further comprising supplying fluid to the pump using the intake chamber.

13. The method of claim 11, further comprising sealing the intake chamber from atmosphere using the mechanical seal.

14. The method of claim 11, further comprising transmitting thrust from the shaft to the motor using angular contact bearings disposed in the motor.

15. A method of using a pump assembly, comprising: supplying fluid to a pump with an intake chamber; sealing the intake chamber from atmosphere using a mechanical seal; coupling a shaft of the pump and a motor rotationally using a coupling disposed between the mechanical seal and the motor; connecting the pump directly to the motor without a thrust chamber by connecting the intake chamber of the pump directly to a bell housing bolted onto the motor, wherein the coupling is disposed in the bell housing; exposing the coupling to atmosphere; rotating the shaft using the motor, thereby driving the fluid through at least one mixed axial and radial flow impeller of the pump connected to the shaft; and wherein each impeller is oriented in the same direction.

16. The method of claim 15, further comprising transmitting thrust from the shaft to the motor using thrust bearings disposed in the motor, wherein the thrust bearings are angular contact ball bearings.

17. The method of claim 16, further comprising filling the motor with oil, thereby lubricating the angular contact bearings.

18. The method of claim 16, wherein the bell housing has a window formed through a wall of the bell housing.

19. The method of claim 17, wherein the angular contact bearings are disposed around a shaft of the motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings 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.

(2) FIG. 1 is a schematic view of one embodiment of a surface pump assembly.

(3) FIG. 2 is a cross-sectional view of the surface pump assembly of FIG. 1.

(4) FIG. 3 is a partial cross-sectional view of the centrifugal pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(5) FIG. 1 is a schematic view of one embodiment of a surface pump assembly 100. FIG. 2 is a cross-sectional view of the surface pump assembly 100. As shown, the surface pump assembly 100 is horizontally mounted and includes a centrifugal pump 110 driven by an electric motor 120. The pump 110 is supported on a skid 105 by a plurality of support members 115. The support members 115 are adapted to prevent rotation of the pump housing 125 of the pump 110. In one embodiment, the support members 115 comprise clamp assemblies that can be bolted to the skid 105.

(6) The pump 110 is coupled directly to the motor 120. As shown, a bell housing 123 connects the motor 120 to the intake chamber 127 of the pump 110. A coupling 130 is used to couple to the motor 120 to the shaft 135, which extends from the bell housing 123 into the pump 110. The motor 120 rotates the shaft 135 to drive the pump 110. One or more seal assemblies 140 are provided to seal around the shaft 135 as it passes through the bell housing 123 and the intake chamber 127. Any suitable seal assembly may be used so long as it is capable of sealing the intake chamber 127 from atmosphere. In one embodiment, the seal assembly 140 is a conventional mechanical seal. The mechanical seal can be a double seal having a buffer fluid supplied from an external pressurization source. In this embodiment, the buffer fluid is retained in a reservoir connected to the skid 105. The seal assembly 140 may optionally include thrust bearings 147 to absorb thrust from the pump 110. As shown in FIG. 2, the motor-shaft coupling 130 is advantageously positioned outside of the pumped fluid. As a result, the coupling 130 may be manufactured from a less expensive material.

(7) In one embodiment, the pump 110 for the surface pump assembly 100 is a multistage centrifugal pump. The pump 110 includes the pump housing 125 connected to the intake chamber 127 at one end and a discharge flange 126 at another. FIG. 3 is a partial cross-sectional view of the pump 110. Disposed within the housing 125 is at least one diffuser 142 coupled to an impeller 144, the combination of which is commonly referred to as a stage 150. The impeller 144 is adapted for rotation by the shaft 135. Each impeller 144 is tightly fitted onto the shaft 135 and connected to the shaft 135 using a suitable connection mechanism, for example, a spline connection. The impeller 144 typically includes a plurality of vanes which impart momentum/velocity to the fluid, when the impeller 144 is rotated about its axis within the diffuser 142. The interaction of the fluid with the diffuser 142 converts this velocity to pressure. In this manner, the fluid pressure exiting the discharge flanged 126 may be increased.

(8) A single stage of diffuser 142 and impeller 144 typically cannot impart the desired momentum to the fluid. Therefore, the pump 110 typically includes a plurality, or multistage, of such diffuser 142 and impeller 144 combinations. As shown, the diffusers 142 are aligned such that the centerlines of each of impellers 144 are collinear. The outlet 152 of each stage 150 delivers pumped fluid to the suction inlet 153 of the next stage 150. The first stage has the opening for receiving fluid from the intake chamber 127, and the final stage has an outlet for discharging the pumped fluid. Each diffuser 142 is configured to enable the serial interconnection of the impellers 144. Preferably, each impeller 144 includes a central hub, having a plurality of vanes extending therefrom. In one embodiment, the hub of the impeller 144 includes a recessed female portion adapted to mate with a splined male portion of an adjacent impeller 144. In this respect, the series of impellers 144 may be commonly rotated by the shaft 135. Typically, the pump 110 will include a sufficient number of stages, such that each stage 150 supplies the fluid at an incrementally higher pressure into the next adjacent stage 150. In this manner, the pump 110 is adapted increase the fluid pressure entering the intake chamber 127 and the discharge the fluid at a predetermined pressure. It must be noted other suitable centrifugal pumps known to a person of ordinary skill in the art may be also be employed.

(9) In operation, fluid is supplied through the intake chamber 127, and the motor 120 is activated to rotate the shaft 135 and the impellers 144. Rotation of the impellers 144 increases the pressure of the fluid flowing through each stage 150. Consequently, a pressure differential is developed across each stage 150, with the discharge side having a higher pressure than the intake side. The pressure differential created during operation imparts an axial force or thrust to the shaft 135. This axial thrust is directed in the direction toward the motor 120. Because the impellers 144 are all oriented in the same direction on the shaft 135, the axial thrust from each impeller 144 is additive. This cumulative axial thrust load is transmitted directly to the motor 120.

(10) The motor 120 is adapted to take the thrust load from the pump 110. The motor 120 is equipped with thrust bearings to carry the load of the rotors. The motor 120 may be filled with oil to provide lubrication for the bearings. In one embodiment, the thrust bearings are adapted and sized to absorb the thrust load from the motor 120, thereby improving performance and minimizing down time. Preferably, angular contact bearings are used to absorb the thrust load. It is believed that angular contact bearings, due to their design, are capable of absorbing relatively more thrust loads than radial ball bearings. It must be noted that the pump assembly 100 may be operated with any suitable electric motor known to a person of ordinary skill in the art so long as the bearings in the motor are effective to absorb the thrust load of the pump.

(11) One advantage of the pump assembly is that manufacturing costs are significantly reduced. This is because the pump assembly may be assembled without a thrust chamber and the associated components. As a result, the assembly process is also simplified. Embodiments of the pump assembly are particularly advantageous for smaller pumping systems, preferably, pumping systems of less than 100 horsepower, and more preferably, pumping systems of less than 50 horsepower.

(12) While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.