This disclosure relates in general to electrical submersible well pumps (ESP), particularly to a thrust bearing having a thrust runner keyed to the shaft and having a radially compressible vibration dampening ring between the thrust runner and the shaft.
Electrical submersible well pumps are often used to pump liquids from hydrocarbon producing wells. A typical ESP includes a pump driven by an electrical motor. The motor is filled with a dielectric lubricant for lubricating motor bearings. A pressure equalizer reduces a differential between the hydrostatic well fluid pressure and the lubricant pressure. The pressure equalizer may be located in a seal section between the motor and the pump.
The well fluid pump generates axial thrust on a drive shaft extending through the seal section. Both down thrust toward the motor and up thrust away from the motor can occur. A thrust bearing unit, usually within the seal section, transfers the down thrust and up thrust to the motor. The thrust bearing unit includes a thrust runner mounted to the shaft for rotation with the shaft. The thrust runner slides on non-rotating down thrust bearing pads during down thrust, transferring the down thrust on the shaft to the housing. The thrust runner slides against non-rotating up thrust bearing pads during up thrust, transferring the up thrust to the housing. The thrust bearing unit may include a screw pump that rotates with the shaft for circulating motor lubricant within the thrust bearing unit. The shaft in the seal section is radially supported at its ends by radial bearings.
The shaft in the seal section may vibrate, particularly at high rotational speeds. Vibration can cause fatigue of components in the seal section. Also, the shaft has a primary mechanical seal at its upper end, and vibration can cause leakage of well fluid into the seal section. The well fluid can migrate through the motor lubricant in the seal section, eventually reaching the motor. Contamination of the motor lubricant in the motor by well fluid can quickly cause failure of the motor.
A submersible pump assembly (ESP) comprises a well fluid pump, a motor, and a seal section between the motor and the well fluid pump. The seal section has a housing with a longitudinal axis. A shaft extends though the housing on the axis, the shaft being driven by the motor for driving the well fluid pump. A thrust bearing base is mounted in the housing for non-rotation relative to the housing. A thrust runner has a runner bore through which the shaft extends. The thrust runner has an outer diameter spaced radially inward from an inner surface of the housing by an annular clearance. The thrust runner is axially secured to the shaft to prevent axial movement of the thrust runner relative to the shaft. The thrust runner is in rotational, sliding engagement with an upper side of the thrust bearing base. A thrust runner wave spring rotates in unison with the shaft and the thrust runner. The thrust runner wave spring is annular, metal and has an inner diameter surface in contact with the shaft and an outer diameter surface in contact with the runner bore. The thrust runner wave spring has a transverse width between the inner diameter surface and the outer diameter surface that is elastically deflectable, exerting an inward bias force against the shaft and an outward bias force against the runner bore to reduce radial vibration movement of the thrust runner.
An annular thrust runner recess is selectively in the runner bore or on the shaft. The thrust runner wave spring is located in the thrust runner recess. In the embodiment shown, the annular thrust runner recess is on the shaft. The annular thrust runner recess may have an upper shoulder facing a lower shoulder. The thrust runner wave spring has an axial dimension less than a distance from the lower shoulder to the upper shoulder.
In the embodiment shown, an axially extending shaft slot is formed on the shaft and an axially extending runner bore slot is formed in the runner bore. A key inserts into both of the slots to cause rotation of the thrust runner in unison with the shaft. The thrust runner wave spring has two ends spaced apart from each other by a gap through which the key extends.
In one embodiment, an annular thrust runner recess is on the shaft, the thrust runner recess having an upper shoulder facing a lower shoulder and a recess cylindrical surface between the upper and lower shoulders. The thrust runner wave spring is located in the thrust runner recess with an inner diameter surface of the thrust runner wave spring in contact with the recess cylindrical surface. An axially extending shaft slot formed on the shaft extends through the upper shoulder and the lower shoulder but not the recess cylindrical surface. An axially extending runner bore slot is formed in the runner bore. A key fits within both of the slots to cause rotation of the thrust runner in unison with the shaft. The key extends through the shoulders of the recess and has an inward facing surface that is at a radial distance from the axis not less than a radial distance from the axis to the recess cylindrical surface. The thrust runner wave spring has two ends spaced apart from each other by a gap through which the key extends.
The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. In an embodiment, usage of the term “about” includes +/−5% of the cited magnitude. In an embodiment, usage of the term “substantially” includes +/−5% of the cited magnitude. The terms “upper” and “lower” and the like bare used only for convenience as the well pump may operate in positions other than vertical, including in horizontal sections of a well.
It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation.
Referring to
ESP 11 also includes an electrical motor 17 for driving pump 12. Motor 17 connects to pump 12 via a seal section 19, which has means for reducing a pressure differential between lubricant within motor 17 and the hydrostatic pressure of well fluid in the well. Intake 15 may be at the lower end of pump 12, in the upper end of seal section 19 or in a separate module. Also, ESP 11 may also include a gas separator, and if so intake 15 would be in the gas separator.
Referring to
Seal section 19 has a conventional pressure equalizer that is not shown but will normally comprise an elastomeric bag. Lubricant from motor 17 communicates through passages in seal section 19 with the interior of the elastomeric bag. Well fluid is admitted into the chamber containing the elastomeric bag for imparting hydrostatic well fluid pressure on the elastomeric bag, which in turn applies the hydrostatic pressure to the motor lubricant. Seal section 19 also has a primary seal, normally a mechanical face seal, in an upper portion of upper connector 27 for sealing well fluid from contact with the motor lubricant in the interior of seal section 19.
In this embodiment, seal section 19 has a thrust bearing assembly for transferring down thrust and up thrust imposed on shaft 21 from pump 12 to housing 25. Seal section 19 could include a separate module for the thrust bearing assembly. The thrust bearing assembly may have various configurations and in this example has a non-rotating base including a down thrust transfer member 29 secured to housing 25 for non-rotation relative to housing 25. Thrust transfer member 29 may have a helical passage 31 on its exterior to allow the flow of motor lubricant between thrust transfer member 29 and housing 25. The base also includes a down thrust bearing 33 mounted on the upper side of thrust transfer member 29 for non-rotation relative to thrust transfer member 29.
A thrust runner 35 is rigidly secured to shaft 21 above thrust transfer member 29 for rotation in unison with shaft 21. Thrust runner 35 is a cylindrical member with bearing pads 37 on its lower side that slidingly engage down thrust bearing 33 to transfer down thrust. Thrust runner 35 also transfers any up thrust that may occur on shaft 21 to non-rotating up thrust pads 39. Thrust runner 35 has appreciable mass, being much larger in outer diameter than shaft 21. It also has a significant axial dimension from its lower end to its upper end.
The thrust bearing assembly may also optionally have an inducer or screw pump 41 for circulating motor lubricant. In this embodiment, screw pump 41 has a helical flight 43 on its exterior that is in close reception with down thrust transfer member bore 45. Screw pump 41 is mounted to shaft 21 for rotation therewith.
In addition to a thrust bearing assembly, seal section 19 also has radial bearing assemblies at the upper and lower ends of housing 25 for providing radial support to shaft 21.
Seal section 19 has one or more thrust runner tolerance rings or wave springs 51 (two shown) between shaft 21 and thrust runner 35. Seal section 19 may also have one or more screw pump tolerance rings or wave springs 53 (two shown) between shaft 21 and screw pump 41. In addition, seal section 19 may have a radial bearing tolerance ring or wave spring 55 between shaft 21 and bearing sleeve 47. The lower radial bearing (not shown) may also have a tolerance ring or wave spring. The various wave springs 51, 53 and 55 reduce vibration of shaft 21, which might occur particularly at high rotational speeds.
Wave springs 51, 53 and 55 are located in annular recesses, and in this embodiment, all of the recesses are selectively located on shaft 21.
Shaft 21 also has a keyway groove or shaft slot 65 extending most of its length and parallel with axis 23. In this embodiment, shaft slot 65 has a radial depth no greater than the radial width of shoulders 57, 59, thus it does not extend through recess cylindrical surface 63. Shaft slot 65 does extend through upper and lower shoulders 59, 61.
A portion of a key 67 extends through shaft slot 65 above and below shoulders 59, 61 and alongside recess cylindrical surface 63. N Key 67 has an inward facing side 66 that is illustrated as being spaced radially outward a slight distance from recess cylindrical surface 63, but it could touch recess cylindrical surface 63. The radial distance from axis 23 to key inward facing side 66 is not less than the radial distance from axis 23 to recess cylindrical surface 63 in this example.
Prior to installation, thrust runner wave spring 51 has a radial or transverse width from its circumscribed outer diameter at outward protruding indentations 71 to its circumscribed inner diameter at inward protruding indentations 73 that is greater than the radial distance from recess cylindrical surface 63 (
As shown in
Thrust runner 35 is axially secured to shaft 21 so as to prevent any axial movement of thrust runner 35 on shaft 21. In this example, a multi-piece upper retainer 75 wedges between shaft 21 and thrust runner bore 68. A retainer ring 77, which may be a snap ring, secures to shaft 21 at the lower end of thrust runner 35.
Referring to
Outward-protruding waves or indentations 71 are permanently formed in thrust runner wave spring 51, creating convex shapes extending around wave spring 51. Outward-protruding indentations 71 extend from upper band 81 to lower band 83 and are parallel with axis 23 (
Referring to
Referring to
In operation, motor 17 and portions of seal section 19 are filled with a dielectric lubricant and assembled with pump 12 to form ESP 11. An operator runs ESP 11 into a well to pump well fluid. Supplying power to the motor 17 rotates shaft 21. The various wave springs 51, 53 and 55 tend to reduce vibration of shaft 21, particularly a high speeds.
The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While only one embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.
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Number | Date | Country | |
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20200362859 A1 | Nov 2020 | US |