RU2300018C2 - Submersible low-speed direct-drive pumping plant - Google Patents

Abstract

FIELD: oil producing and construction industry.

SUBSTANCE: invention relates to electric machine building and it can be used at designing of submersible plants using as low speed drive of rodless submersible pumps, mainly screw pump, oil-filled synchronous electric motors. Proposed submersible low-speed direct-drive pumping plant for producing formation fluid has control station, three-phase ac supply source and submersible electric pumping unit lowered into well on tubings and consisting of electric motor with hydraulic protections whose windings are connected into star. Pump and cable line. Pump is made in form of screw machine, and electric motor, in form of synchronous electric motor with salient-pole stator, outer surface of poles being either smooth or provided with radial teeth, no-winding rotor on outer surface of which radial teeth are made. Identical inductive windings connected into phases are wound on poles of stator. Each consists of two parallel arms, each including series-connected diode and windings. Diodes in parallel arms are connected, in opposition, and phases are connected through cable line conductors to ac sine voltage source. Diodes are connected into assembly arranged in submerged part of plant to provided possibility of use of three-wire cable line to supply voltage to electric motor.

EFFECT: simplified design of plant, improved efficiency of oil production and reliability in operation.

4 cl, 2 dwg

Description

The invention relates to electrical engineering and can be used in the oil and construction industries for the creation of submersible units having, as a low-speed drive, rodless submersible pumps, mainly screw, oil-filled synchronous motors. The invention is aimed at intensifying the production of formation fluid, including oil, during the operation of medium and low-production wells, as well as wells located in difficult geological conditions, and, in addition, can be used in construction drilling equipment for pumping water and other fluid from wells for various purposes.

A known design of a submersible oil-filled electric motor [RF patent No. 2162272], comprising a head in which a cable entry is located, consisting of a plug, the housing of which is attached to the head, the pins are connected to a cable and a socket containing a block of dielectric material and sleeves connected to output wires of the stator winding. At the same time, the block and sleeves are installed hermetically, and a through axial hole is made in the block, in which a bypass valve is placed to communicate and disconnect the motor cavity with the cavity bounded by the plug body and the block.

Known synchronous motor with variable magnetic resistance according to the application of France No. 7418161 (patent analogue in the US No. 4039908) having a stator containing 3n pole pairs on which identical inductive coils are located, as well as a passive rotor located coaxially relative to the stator. The outer surface of the poles of the stator and rotor have a tooth zone, and the number of teeth on the rotor is two less than the number of teeth on the poles of the stator, taking into account the teeth that would be located in the spaces between the poles. The coils at the poles are connected in a "star", each terminal of which is powered by one phase of a three-phase AC source. For this, the coils are combined in groups of two with one diode, and the groups are connected in parallel in such a way that they allow the passage of oppositely directed magnetic fluxes at two adjacent poles.

Known synchronous motor [RF patent No. 2145460], which is an electric machine consisting of a stator and a passive windingless rotor. The stator contains n distinct poles, where n≥4. The surface of the poles is smooth or provided with a serrated zone. Identical inductive coils are wound at all poles of the stator, connected in phases, each phase consisting of two parallel branches, each of which includes a diode and a coil connected in series, moreover, the diodes in parallel branches are counter-connected, one phase terminal is connected to the zero the input of the motor, and the other output to a source of alternating sinusoidal voltage.

A known installation of a submersible centrifugal pump [2217579], adopted as a prototype, and consisting of a submersible electric pump unit combining an electric motor with hydraulic protection, a pump and a cable line, lowered into the well by lifting tubing, wellhead equipment, a control station and a transformer.

Currently, for pumping viscous grades of oil from wells, as well as during the operation of medium- and low-production wells and wells located in difficult geological conditions, the use of screw pumps, which have a number of advantages compared to centrifugal pumps, is most effective. Moreover, world practice shows that the most preferred for continuous operation of pumps, especially screw pumps, are speeds in the range of 100-500 rpm. To ensure such revolutions, submersible pump units are currently available with an overhead drive. To do this, the electric motor and a speed-reducing mechanism, such as a gearbox, are located on the surface, and the rotation to the submersible pump located in the well is transmitted using rotating rods. Despite the additional difficulties that arise during the installation and operation of such installations, they are widely used in the oil industry. In addition, there are installations with submersible gear inserts, which also complicate the design of the electric pump unit and reduce its reliability.

The present invention is aimed at solving the problem of simplifying the design of the installation, increasing the efficiency of viscous oil production in difficult geological and technical conditions through the use of screw pumps and low-speed gearless synchronous electric motors, as well as simplifying the installation and ease of maintenance of equipment lowered into the well, and, accordingly, increasing the reliability of the installation.

The technical result achieved during the implementation of the invention consists in reducing the speed of the pump drive to optimal values and in localizing the location of the diode assembly, through which the synchronous motor is powered from the alternating sinusoidal voltage network, directly near the motor or in its housing, as well as in increasing the operational reliability of the installation, including its cable line.

This is achieved due to the fact that, similarly to the prototype, in a submersible pump installation there are a control station located on the surface and a three-phase AC voltage source, as well as an electric submersible pump unit consisting of a hydraulic motor with windings connected to a star, a pump and a cable line. However, in the proposed solution, the pump unit is made in the form of a screw pump as the most productive when pumping viscous and heavy grades of oil, the electric motor is made in the form of a synchronous electric motor, according to the technical solution of which it has a stator with distinct poles, the outer surface of which is smooth or equipped with radial teeth , a windingless rotor, on the outer surface of which radial teeth are made, identical inductive windings connected in phases are wound on the stator poles , each phase consists of two parallel branches, each of which includes a diode and windings connected in series, moreover, the diodes in the parallel branches have an on-off connection, the phases are connected through the cable line wires to a source of alternating sinusoidal voltage. In addition, the diodes are combined in an assembly located in the submersible part of the installation, which makes it possible to use a 3-wire cable line to supply voltage to the electric motor.

In the particular case of using the proposed technical solution in the aforementioned synchronous electric motor, the width of the stator teeth does not exceed 0.7 of the width of the interdental groove of the rotor, and the width of the teeth of the rotor does not exceed 0.7 of the width of the interdental groove of the stator.

In the second particular case of the use of this technical solution, the combination of its features is supplemented by the location of the diode assembly directly in the motor housing, which increases the operational reliability of the installation.

In the third particular case, the installation is supplemented with a frequency converter located next to the power source, which makes it possible to smoothly control the frequency of rotation of the electric motor both up and down, while maintaining a high specific torque. This will allow you to adapt the performance of the installation to the changing flow rate of the well.

The essence of the proposed technical solution is illustrated by the following drawings:

Figure 1 shows a diagram of the basic structural elements of a submersible pump installation.

Figure 2 shows the connection diagram through the diode assembly of the electric motor to a source of alternating sinusoidal voltage.

The submersible pump installation according to the proposed technical solution comprises a control station and a power source 1, as well as an electric submersible unit lowered into the well on lifting tubing, consisting of a screw pump 5, a synchronous motor 4 with hydraulic protection, the windings of which are connected in a "star", diode unit 3 and 3-wire cable line 2, providing voltage supply to the motor. The stator of the electric motor is made with distinct poles, the outer surface of which is smooth or provided with radial teeth, the rotor is winding-free and radial teeth are made on its outer surface, identical inductive windings connected in phases are wound on the stator poles, and each phase consists of two parallel branches , each of which includes a diode and a winding connected in series, the diodes in parallel branches are turned on, and the phases are connected to the unit through the wires of the cable line -mentioned AC sinusoidal voltage source.

Submersible installation operates as follows. At a signal from the control station, a voltage is applied to the electric motor via cable. In this case, a voltage of one phase of the source is supplied to each phase of the motor. Since the voltage on the windings of each phase is supplied through diodes connected in opposite directions, only positive half-waves of voltage are supplied to the windings of one phase branch, and only negative ones to the windings of the other phase branch. So, alternately, voltage pulses in the form of half-waves with a duration equal to a half-period of voltage change and with an offset for branches of one phase equal to a half-cycle arrive in phase windings of each pair of branches. In this case, the voltage pulses arriving at each pair of phase branches are additionally offset from each other in accordance with the phase shift of the power source.

Accordingly, under the action of each voltage pulse, a current pulse is formed in the windings of one phase branch, which, in turn, creates magnetic fluxes in the stator poles and causes magnetic forces between the stator pole teeth and the rotor teeth. In this case, the radial components of the attractive forces of the poles of one phase located symmetrically are mutually balanced, and the tangential components of these forces create a torque on the rotor, under the influence of which the rotor tends to rotate to the position of alignment of the teeth of the rotor with the teeth of the excited pole. At neighboring poles, the teeth of which are offset, for example, by an amount equal to the tooth pitch divided by the number of phases of the motor, the magnetic fluxes that are excited in them during the circular distribution of voltage pulses also create a torque on the rotor. The torques that arise under the action of simultaneously excited poles are summed on the rotor, and the movement of the rotor per revolution of the voltage pulses in the stator is equal to one tooth step. This achieves a reduction in the frequency of rotation of the voltage pulses. The resulting torque from the engine is transmitted through a special coupling to the screw pump.

Claims (4)

1. Submersible low-speed gearless pumping unit for producing formation fluid, comprising a control station, a three-phase AC voltage source and a submersible electric pump unit lowered into the borehole on lifting tubing, consisting of a hydraulic motor with windings connected to a star, a pump and cable line, characterized in that the pump is made in the form of a screw pump, and the electric motor in the form of a synchronous electric motor having a stator with pronounced poles mi, the outer surface of which is smooth or provided with radial teeth, a windingless rotor, on the outer surface of which radial teeth are made, identical inductive windings connected in phases are wound on the poles of the stator, with each phase consisting of two parallel branches, each of which includes diodes and windings connected in series, moreover, the diodes in the parallel branches are counter-turned on, the phases are connected through the cable line wires to a source of alternating sinusoidal voltage, while diodes are combined in an assembly located in the submersible part of the installation to enable the use of a 3-wire cable line to supply voltage to the electric motor. 2. Installation according to claim 1, characterized in that in the synchronous electric motor the width of the stator teeth does not exceed 0.7 of the width of the interdental groove of the rotor, and the width of the teeth of the rotor does not exceed 0.7 of the width of the interdental groove of the stator. 3. Installation according to claim 1, characterized in that the diode assembly is located in the motor housing. 4. Installation according to claim 1, characterized in that the source of alternating voltage comprises a frequency converter.

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