A submersible motor protection device

Abstract

The utility model provides a kind of submersible motor protection device, comprising: center shaft, the first cavity with motor oil inside being arranged around center shaft and the second cavity with well fluid inside being arranged around the first cavity, the first cavity is separated from the second cavity by the communication pipe coaxial with center shaft, and the bottom of communication pipe has the communication hole for the first cavity and the second cavity communication, in along flow path direction, motor oil and well fluid are provided with isolating liquid, the density of isolating liquid is greater than the density of well fluid and the density of motor oil. The utility model can better seal, breathe compensation and protective effect to submersible motor.

Description

Technical Field

[0001] This utility model belongs to the field of electric submersible pump technology, specifically, it relates to a protection device for a submersible motor. Background Technology

[0002] Submersible electric pumps (ESPs) play a crucial role in heavy oil production. In recent years, the proportion of production from ESP wells has gradually increased, leading to greater demand for large-scale development in heavy oil blocks. Simultaneously, the number of ESP wells and their production have continued to rise, making the service life and stable operation of ESPs paramount. Currently, ESP protectors are typically a combination of bladder and settling type protectors. Furthermore, the properties of the fluid produced in heavy oil wells vary significantly. During motor load changes, the protector comes into contact with and exchanges fluids with the well fluid during "breathing," which can easily lead to rapid protector failure. Utility Model Content

[0003] One objective of this invention is to provide a protection device for a submersible motor, which provides better sealing, breathing compensation, and protection for the submersible motor.

[0004] According to this utility model, a submersible motor protection device is provided, comprising: a central shaft, a first cavity surrounding the central shaft and containing motor oil, and a second cavity surrounding the first cavity and containing well fluid. The first cavity and the second cavity are separated by a connecting pipe coaxial with the central shaft, and the bottom of the connecting pipe has a connecting hole connecting the first cavity and the second cavity. Along the flow path direction, an isolation fluid is provided between the motor oil and the well fluid, and the density of the isolation fluid is greater than the density of the well fluid and the density of the motor oil.

[0005] In a preferred embodiment, the submersible motor protection device further includes: a housing, wherein the first cavity, the second cavity, and the connecting pipe are all disposed inside the housing.

[0006] In a preferred embodiment, the submersible motor protection device further includes: a connector portion disposed on the upper part of the housing and a guide portion disposed on the lower part of the housing, wherein the central shaft passes through the interior of the connector portion, the housing, and the guide portion.

[0007] In a preferred embodiment, the connector has a cylindrical accommodating space inside, and a portion of the central shaft is located within the accommodating space and is sealed to the connector via a first mechanical seal.

[0008] In a preferred embodiment, the second cavity is connected to the accommodating space via a pipe, which passes through the interior of the accommodating housing and the connector.

[0009] In a preferred embodiment, the submersible motor protection device further includes: a shaft protector sleeve fitted on the outer surface of the central shaft, the upper surface of the shaft protector sleeve, the inner wall of the joint and the outer surface of the central shaft forming a communicating space, the lower part of the communicating space communicating with the first cavity, and the upper part of the communicating space being connected to external well fluid through a one-way valve.

[0010] In a preferred embodiment, the central shaft and the communicating space are sealed together by a second mechanical seal.

[0011] In a preferred embodiment, the connecting pipe is disposed between the bottom end face of the connector and the top end face of the guide, and a portion of the protective shaft tube is disposed inside the connecting pipe.

[0012] In a preferred embodiment, the inner wall of the connecting pipe, the bottom end face of the connector, the top end face of the guide, and the outer surface of the protective shaft tube together form the first cavity.

[0013] In a preferred embodiment, the bottom end face of the connector, the inner wall of the accommodating housing, the outer wall of the connecting pipe, and the top end face of the guide portion together form the second cavity.

[0014] This utility model has at least the following technical effects:

[0015] According to this utility model, a central shaft, a first cavity containing motor oil arranged around the central shaft, and a second cavity containing well fluid arranged around the first cavity are provided. The first cavity and the second cavity are separated by a connecting pipe coaxial with the central shaft, and the bottom of the connecting pipe has a connecting hole connecting the first cavity and the second cavity. An isolation fluid, with a density greater than that of the well fluid, is provided between the motor oil and the well fluid along the flow path. When the motor oil in the first cavity overflows to a certain extent, an equilibrium state is reached. Each time the unit breathes, the isolation fluid dynamically floats at the bottom of the first and second cavities, preventing further overflow of motor oil. Since the density of the external well fluid is less than that of the isolation fluid, the well fluid is always isolated in the second cavity by the isolation fluid, preventing it from entering the submersible motor, thus providing better sealing, breathing compensation, and protection for the submersible motor. Attached Figure Description

[0016] Figure 1 A schematic diagram of the overall structure of a submersible motor protection device according to an embodiment of the present invention is shown.

[0017] In this application, all the accompanying drawings are schematic drawings, used only to illustrate the principle of the present invention, and are not drawn to scale. Detailed Implementation

[0018] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0019] In the description of the utility model, it should be understood that the terms "inner" and "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the utility model.

[0020] In this utility model, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0021] like Figure 1 As shown, the submersible motor protection device 100 of this utility model includes: a central shaft 3, a first cavity 11 surrounding the central shaft 3 and containing motor oil, and a second cavity 12 surrounding the first cavity 11 and containing well fluid. The first cavity 11 and the second cavity 12 are separated by a connecting pipe 7 coaxial with the central shaft 3. The bottom of the connecting pipe 7 has a connecting hole that connects the first cavity 11 and the second cavity 12. Along the flow path direction, an isolation fluid is provided between the motor oil and the well fluid. The density of the isolation fluid is greater than the density of the well fluid and the motor oil. The top of the second cavity 12 is connected to the external well fluid. When the motor oil does not expand, the isolation fluid in the first cavity 11 is located at the lower part of the motor oil, and the isolation fluid in the second cavity 12 is located at the lower part of the well fluid.

[0022] The working principle of the submersible motor protection device 100 described in this utility model is briefly described below. When the submersible motor is running, the motor oil inside the first chamber 11 heats up and expands in volume, pushing the isolation fluid inside through the connecting hole and into the second chamber 12. When the level of the isolation fluid inside the first chamber 11 drops to the connecting hole at the bottom of the connecting pipe 7, some of the motor oil inside the first chamber 11 can overflow into the second chamber 12 and mix with the well fluid above the isolation fluid. Conversely, as the temperature of the motor oil decreases, the motor oil is drawn back and compensated by the motor, causing the level of the isolation fluid inside the first chamber 11 to rise and the level of the isolation fluid inside the second chamber 12 to fall. When the motor oil overflows to a certain extent in the first chamber 11, an equilibrium state is reached. Each time the unit breathes, the isolation fluid dynamically floats at the bottom of the first chamber 11 and the second chamber 12, preventing further overflow of motor oil. Since the density of the external well fluid is less than that of the isolation fluid, the well fluid is always isolated in the second chamber 12 by the isolation fluid, preventing it from entering the first chamber 11 and thus preventing it from entering the submersible motor. This provides better sealing, breathing compensation and protection for the submersible motor.

[0023] In one or more embodiments, the submersible motor protection device 100 of the present invention further includes: a housing 5, wherein a first cavity 11, a second cavity 12, and a connecting pipe 7 are all disposed inside the housing 5.

[0024] In one or more embodiments, the submersible motor protection device 100 of this utility model further includes: a connector portion 1 disposed on the upper part of the housing 5 and a guide portion 8 disposed on the lower part of the housing 5, wherein a central shaft 3 passes through the interior of the connector portion 1, the housing 5, and the guide portion 8. The bottom end of the connector portion 1 and the top end of the guide portion 8 are both inserted into the interior of the housing 5 and connected to the housing 5 by threads.

[0025] In one or more embodiments, the interior of the connector 1 has a cylindrical accommodating space, and a portion of the central shaft 3 is located within the accommodating space and is sealed to the connector 1 by a first mechanical seal 2.

[0026] In one or more embodiments, the second cavity 12 inside the housing 5 is connected to the accommodating space via a connecting pipe. Optionally, the connecting pipe passes through the interior of the housing 5 and the connector 1.

[0027] In one or more embodiments, the submersible motor protection device 100 of the present invention further includes: a shaft guard tube 6 sleeved on the outer surface of the central shaft 3, the upper surface of the shaft guard tube 6, the inner wall of the joint 1 and the outer surface of the central shaft 3 forming a communicating space s, the lower part of the communicating space s communicating with the first cavity 11, and the upper part of the communicating space s being connected to external well fluid through a one-way valve.

[0028] In one or more embodiments, the central shaft 3 is sealed to the communicating space by a second mechanical seal 4.

[0029] In one or more embodiments, the connecting pipe 7 is disposed between the bottom end face of the connector 1 and the top end face of the guide 8, and a portion of the shaft guard 6 is disposed inside the connecting pipe 7. The inner wall of the connecting pipe 7, the bottom end face of the connector 1, the top end face of the guide 8, and the outer surface of the shaft guard 6 together form a first cavity 11.

[0030] In one or more embodiments, the bottom end face of the connector 1, the inner wall of the housing 5, the outer wall of the connecting pipe 7, and the top end face of the guide 8 together form a second cavity 12.

[0031] In one or more embodiments, the connector 1 is connected to the separator or inlet of the submersible electric pump unit, and the guide 8 is connected to the protection mechanism located at its lower end and communicates with the interior of the submersible motor.

[0032] Although the present invention has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A submersible motor protection device, characterized in that, include: The system comprises a central shaft, a first cavity containing motor oil arranged around the central shaft, and a second cavity containing well fluid arranged around the first cavity. The first cavity and the second cavity are separated by a connecting pipe coaxial with the central shaft, and the bottom of the connecting pipe has a connecting hole connecting the first cavity and the second cavity. Along the flow path, an isolation fluid is provided between the motor oil and the well fluid, and the density of the isolation fluid is greater than the density of the well fluid and the density of the motor oil.

2. The electrical submersible motor protection apparatus of claim 1, wherein, Also includes: The housing includes a first cavity, a second cavity, and a connecting pipe, all of which are located inside the housing.

3. The electrical submersible motor protection apparatus of claim 2, wherein, Also includes: A connector portion is provided on the upper part of the housing and a guide portion is provided on the lower part of the housing, and the central shaft passes through the interior of the connector portion, the housing, and the guide portion.

4. The electrical submersible motor protection apparatus of claim 3, wherein, The connector has a cylindrical accommodating space inside, and part of the central shaft is located within the accommodating space and is sealed to the connector by a first mechanical seal.

5. The electrical submersible motor protection apparatus of claim 4, wherein, The second cavity is connected to the accommodating space through a pipe, which passes through the interior of the accommodating shell and the connector.

6. The electrical submersible motor protection apparatus of claim 5, wherein, Also includes: A protective tube is fitted onto the outer surface of the central shaft. The upper surface of the protective tube, the inner wall of the joint, and the outer surface of the central shaft together form a communicating space. The lower part of the communicating space is connected to the first cavity, and the upper part of the communicating space is connected to external well fluid through a one-way valve.

7. The electrical submersible motor protection apparatus of claim 6, wherein, The central shaft and the communicating space are sealed together by a second mechanical seal.

8. The electrical submersible motor protection apparatus of claim 7, wherein, The connecting pipe is disposed between the bottom end face of the connector and the top end face of the guide, and part of the shaft guard is disposed inside the connecting pipe.

9. The electrical submersible motor protection apparatus of claim 8, wherein, The inner wall of the connecting pipe, the bottom end face of the connector, the top end face of the guide, and the outer surface of the protective shaft tube together form the first cavity.

10. The electrical submersible motor protection apparatus of claim 9, wherein, The bottom surface of the connector, the inner wall of the housing, the outer wall of the connecting pipe, and the top surface of the guide form the second cavity.

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