Electric submersible pump floating ring bearing and method to assemble same

Abstract

A floating ring bearing for an electric submersible pump (ESP) assembly disposable within a cased wellbore and a method to assemble the same are disclosed. The ESP assembly includes a motor, a pump, and a shaft coupling the pump to the pump motor. One or more floating ring bearings are disposed within the motor and the pump, each floating ring bearing circumscribing the shaft to radially support the shaft. A floating ring is disposed within each floating ring bearing. The floating ring circumscribes the shaft so that the floating ring rotates about the shaft in response to rotation of the shaft.

Description

[0001]This application claims priority to and the benefit of co-pending U.S. Provisional Application No. 61 / 448,470, by Forsberg, filed on Mar. 2, 2011, entitled “ELECTRIC SUBMERSIBLE PUMP FLOATING RING BEARING,” which application is incorporated herein by reference.FIELD OF THE INVENTION[0002]This invention relates in general to bearings supporting a rotating member and, in particular, to bearings supporting rotating shafts of an electric submersible pump and a method to assemble the same.BRIEF DESCRIPTION OF RELATED ART[0003]Wells may use an artificial lift system, such as an electric submersible pump (ESP) to lift well fluids to the surface. Where ESPs are used, the ESP may be deployed by connecting the ESP to a downhole end of a tubing string and then run into the well on the end of the tubing string. The ESP may be connected to the tubing string by any suitable manner. In some examples, the ESP connects to the tubing string with a threaded connection so that an uphole end or di...

AI Technical Summary

Benefits of technology

[0009]In accordance with another embodiment of the present invention, an electric submersible pump (ESP) assembly disposable within a cased wellbore is disclosed. The ESP assembly includes a motor, a pump, and a shaft coupled between the pump and the motor. A stationary journal defines a bore through which the shaft extends and fluid circumscribes the shaft in the stationary journal. An annular ring floats in the fluid coaxial with an axis of the shaft and rotatable with respect to the shaft to reduce the rotational inertia of the fluid resulting from rotation of the shaft, the annular ring rotating at a slower speed than the shaft so that fluid between the ring and the shaft has a higher rotational inertia than the fluid between the ring and the stationary journal.

[0011]The disclosed embodiments provide a bearing that can offer improved damping and vibration characteristics. In addition, this bearing type may be used in a system with high vibration to improve the energy dissipation of the rotating shaft and, consequently, the vibration characteristics. Furthermore, the disclosed embodiments will experience reduced wear, such as abrasive wear, compared to similarly situated bearings. This is because the effective velocity between the shaft and the ring, and the ring and the journal is lower.

Problems solved by technology

These types of bearings face problems in environments where high vibration may occur, for example in an eccentrically loaded shaft of an ESP or an imbalanced rotating shaft of the ESP.

In addition, due to the relatively thin lubrication layer between the sleeve and the insert, the bearing may be subject to a high degree of wear at the high rotational operating speeds experienced by ESPs.

This leads to a significantly shorter life that may necessitate frequent replacement of the bearings.

Replacing rotary bearings in an ESP may be extremely costly, particularly where the ESP is positioned within increasingly deep wellbores.

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