RU2455527C1 - Electrical bore-hole pump with common casing - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: electrical bore-hole pump includes pump section, inlet section, section of protection device and section of electrical motor, which includes power supply and communication unit, and common casing passing above all the pump sections.

EFFECT: creation of compact pump due to combination of functions of casings of the pump section, casing of inlet section and multiple casings of protection device section into one common casing, which reduces the problems with joints, misalignment of bearings and reduces concentricity error.

7 cl, 3 dwg

Description

FIELD OF THE INVENTION

The present invention relates to electric submersible pumps, which are typically used to provide mechanized production in low pressure oil wells to lift oil to the surface. In particular, the present invention relates to housings used in such pumps.

BACKGROUND

In FIG. 1 shows a known electric submersible pump. Such pumps are well known in the oil industry, they are installed with immersion in oil wells and used to pump oil to the surface. The electric submersible pump shown in FIG. 1, contains a section 10 of a control and measuring device with electronic circuits, one or more sections 12 of an electric motor (two shown), each of which contains a stator and a rotor mounted on the drive shaft, section 14 of the protective device, which includes four separate housings, an input the hole 16 of the pump and the number of sections 18 of the pump (four are shown here, although the number of sections can be selected in accordance with the height of the feed and the volume of fluid pumped by the pump). A separate casing is provided for each section, which means that in a conventional electric submersible pump system there can be up to 11 casing (four casing of the pump section, two casing of the motor section, one casing of the inlet section and four casing of the protective device section).

In a conventional electric submersible pump assembly, pump housings provide placement of pump sections and bearings, and also provide counter forces to compress a number of pump diffusers. The pump inlet section is usually a separate device that is installed between the pump section and the protective device section (existing pumps have a complete design of the pump inlet section, but the protective device section is separate from it). Such a section of the protective device is made of several housings with internal components attached to them, which are separated by parts of the casing of the protective device, all of which are combined into a section of the protective device at the factory. The pump sections, the inlet section and the section of the protective device are assembled in place, using designs with flange or bolt connection, into the finished unit of the electric submersible pump together with the electric motor.

Many problems are associated with well-known systems, including concentricity errors in the assembly due to accumulation of manufacturing tolerances, problems associated with joints caused by factory defects, and vibrations resulting, for example, from misalignment of the bearing in integrated housings. However, to avoid these problems in a simple way is difficult due to the method of manufacturing such pumps, which involves the manufacture of each section separately with its casing.

The aim of the present invention is to provide a system that is less prone to these problems.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided an electric submersible pump comprising a pump section, an inlet section, a protective device section and an electric motor section including a power supply and a communication unit, and a common casing extending over all pump sections.

Preferably, the common casing comprises a first part accommodating a pump section, an inlet section and a protective device section, a second part containing a power section of an electric motor section, and a third part containing a communication section of an electric motor section

Typically, the pump section contains a set of diffusers held in compression by the first part of the casing. The components of the inlet section and the section of the protective device are also held in compression by the first part of the casing.

Typically, the casing in the area of the inlet section comprises inlets closed by a screen.

The third part of the casing covering the communication unit is usually connected to the second part of the casing covering the power supply by means of a pin connection. This provides precise rotational alignment. The remaining sections can be connected by threaded connections.

The pump may further comprise a groove made in the casing to accommodate the power cable.

Other aspects of the present invention will be apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

In FIG. 1 shows a known electric submersible pump.

In FIG. 2 shows an electric submersible pump in accordance with an embodiment of the present invention.

In FIG. 3 shows a detailed view of the embodiment shown in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 2 shows an embodiment of an electric submersible pump in accordance with the present invention. The electric submersible pump comprises one motor section 20, a protective device section 22 with a transition pipe and a pump inlet, and one pump section 24. The full length of the pump is less than 12 m.

In FIG. 3 is a sectional view of the electric submersible pump shown in FIG. 2, comprising (from left to right) a communication section 20, an engine section 23, an adapter pipe section 21 connected to the upper part of the engine section 23, a protective device section connected to the adapter pipe section, and a pump section 24 connected to the upper part of the protective section 22 devices. The integral shaft 26 passes through all these sections.

The engine section 20 comprises a communication unit 30 located at its lower end for controlling an engine located inside a part 31 of a casing of the communication unit. The farthest end of the shaft 26 is made with a locking ring 32, on which various rotating components of the pump are held. The power supply unit of the engine includes a casing 34 with a stator 36 mounted on its inner surface. The rotor 38 is mounted on a shaft 26 inside the stator 36. The motor is preferably a direct current motor with a plurality of rotor magnetic poles.

The shaft extends from the engine section 20 through the adapter pipe section 21 to the protective device section 22, designed to separate the engine section from the pump section, which are located in the casing part 39. The protective device section contains three pressure compensation bags 40, each of which is connected to a high-speed mechanical seal 42. The protective device section also includes a pump inlet with inlets 43 located in the casing 39 and covered by a screen, and other seals and filters for prevent liquid from entering the engine cover 34.

The shaft 26 extends from the protective device section to the pump section 24. The pump contains a continuation of the casing 39, having a set of diffusers 46 attached to it. A set of 46 diffusers and internal components of the inlet, a section of the protective device and a section of the adapter pipe are held in compression by the casing 39. The impellers 48 corresponding to the diffusers 46 are mounted on the shaft 26 with the possibility of their placement near the diffusers and form the elements of a centrifugal pump. A coupling nut 50 is provided on the upper part of the shaft in the pump section. When tightening the coupling nut 50, the impellers and other components mounted on the shaft 26 are compressed with each other and held in contact with the snap ring 32.

The compact design of the electric submersible pump in accordance with the present invention allows to reduce the total number of individual casings from 11 casings in the known electric submersible pump system to three casings (casing of the pump section / inlet section / section of the protective device, casing of the engine section, casing of the communication unit). This reduction in the number of casings can be achieved by several of the following properties of the compact design of the pump according to the invention:

1) the reduced length of the pump sections due to the reduction of the pump stages as a result of an increase in operating speeds up to 6000 rpm;

2) the reduced length of the engine sections due to the use of the design of a high power DC motor;

3) the combination of the functions of the casings of the pump section, the casing of the inlet section and the plurality of casings of the section of the protective device are combined into one casing.

A reduced number of casing joints in a common assembly means reduced concentricity errors in the assembly due to accumulated manufacturing tolerances, reduced risks associated with joints of problems caused by factory defects, and lower vibration levels (fewer possibilities for bearing misalignment in integrated housings).

In the electric submersible pump assembly in accordance with the present invention, the pump diffusers the inlet section housing and the protective device housings can be held in compression by the reaction force exerted by the combined single casing. A complete assembly can be manufactured at the factory, rather than assembled locally. The functions of the housing of the inlet section of the pump (the entry of the borehole fluid into the pump section and protection against downhole scree) are combined in the casing of the compact pump.

If a compact pump with a large diameter (for example, with an outer diameter of 111 mm of the pump section) is installed in a small common casing (for example, with an internal diameter of 120), a partial introduction of the power cable into the discharge groove made in the outer periphery of the casing may be required pump / safety device. This discharge groove can vary in depth from zero on the discharge side (top) of the pump section, where the highest pressure drop between the internal and external parts of the pump is up to 4 mm in depth at the pump inlet, where the pressure drop is the lowest, and keep this depth the entire length of the protective device section. The purpose of this discharge is to provide additional space inside the casing with an inner diameter of 120 mm to accommodate the power cable.

In the compact electric submersible pump described above, both the casing joints in the pump section / inlet section / protective device and the upper casing joint in the engine section are usually made as threaded joints. The joints of the casing on the base of the engine and the top of the communication unit preferably have a pin connection to ensure accurate angular alignment between the motor stator and the communication unit.

Other changes within the scope of the present invention are apparent.

Claims (7)

1. An electric submersible pump comprising a pump section, an inlet section, a protective device section and an electric motor section including a power supply unit and a communication unit, and a common casing extending over all sections of the pump. 2. The pump according to claim 1, in which the common casing contains a first part accommodating the pump section, an inlet section and a protective device section, a second part containing the power supply section of the electric motor, and a third part containing the communication unit of the electric motor section. 3. The pump according to claim 2, in which the section of the pump contains a set of diffusers held in compression by the first part of the casing. 4. The pump according to claim 3, in which the components of the inlet section and sections of the protective device are also held in compression by the first part of the casing. 5. The pump according to any one of the preceding paragraphs, in which the casing in the area of the inlet section contains inlet openings closed by a screen. 6. The pump according to claim 2, in which the third part of the casing is connected to the second part of the casing by means of a pin connection. 7. The pump according to claim 1, additionally containing a groove made in the casing to accommodate the power cable.

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