RU2300022C1 - Submersible centrifugal high-pressure electric pump for lifting liquid from well - Google Patents

Abstract

FIELD: oil producing industry.

SUBSTANCE: proposed electric pump contains drain valve, sludge branch pipe check valve with spring holder of shutoff device, section of pump with inlet module or gas separator and submersible electric motor with hydraulic protection series-connected by means of tubings. Marking of pump with sludge pipe and check valve provided with holder keeping shutoff device in one position during operation precludes choking of check valve when centrifugal electric pump and upper stages of pump are lowered after stopping.

EFFECT: provision of stable operation of pump under unfavorable conditions at failure of delivery.

2 dwg

Description

The invention relates to the field of pump engineering and can be used in submersible centrifugal pumps for the production of formation fluid (oil) from wells.

Known submersible centrifugal high-pressure electric pump for lifting liquids from wells, containing drain and check valves, slurry pipe, pump sections with an input module or gas separator and a submersible electric motor with hydraulic protection, filled with oil, connected in series (RU 2140575 C1, class F04D 13/10, 12/16/1997).

The disadvantages of this pump include the occurrence of a supply interruption when free gas enters the intake of the pump or when the pump switches from a higher density liquid to a lower density liquid (the transition of pumping the kill fluid to reservoir fluid-oil). As a result, accelerated wear of the working parts of the electric centrifugal pump, its heating, melting of the extension cord, cable and the installation failure occurs.

The problem solved by the invention is to increase operational reliability and durability by eliminating the possibility of interruption of supply, as well as facilitating the conclusion of the well on the mode.

The technical result is achieved by the fact that the shut-off device of the non-return valve rises above the spring holder after starting up the installation and is above it in the process of operation. When the flow rate drops to 0 cubic meters / day, the locking device lowers to the spring holder and does not close the check valve. When the unit is turned off, the pressure under the shut-off device drops sharply and the fluid from the tubing, pressing the shut-off device, overpowers the resistance of the holder, closes the check valve.

The invention is illustrated in the drawing, where figure 1 shows a centrifugal electric pump for lifting fluid from wells; figure 2 - check valve with a spring retainer locking device.

The submersible centrifugal pump consists of an asynchronous motor 1 with a cable current lead 2, a compensator 3, a tread 4, a centrifugal multistage multi-section pump 5 with a filter 6, a check valve 8, a slurry pipe 7 and a drain valve 9. The shaft of the electric motor 1 by means of splined couplings 10, 11 and 12 is connected to the shaft of the tread 4 and the centrifugal pump 5. The check valve 8 consists of a housing 13, a locking device 14, a guide cylinder 16, a spring holder of the locking device 15, a locking ring 17, a sludge trap 1 8 with flow channels 19.

Submersible centrifugal pump operates as follows.

Rotating, the shaft of the motor 1 through the spline coupling 12 transmits the rotation of the tread shaft 4 and then through the spline couplings 10 and 11 rotates the shaft of the centrifugal pump 5. The formation fluid through the filter 6 enters the lower stages of the pump 5 and then through the pump through the check valve 8 through the gap between a guide cylinder 16 and a shut-off device 14, through a slurry pipe 18 and a drain valve 9 into a tubing string (string not shown).

During the operation of a centrifugal high-pressure pump, especially in low-production wells and with a high gas factor, even in spite of the presence of a gas separator, supply failures occur. Disruption of supply occurs due to the fact that the pressure created by the pump due to the ingress of free gas to the working parts of the pump becomes less than what it created before under normal operating conditions. This closes the check valve. As soon as the check valve is closed, the flow of fluid through the pump stops and its rapid heating occurs. Due to the absence of fluid flow in the pump, an oil and gas emulsion is formed, on which a centrifugal pump sharply reduces the pressure. At high temperature, salts are deposited in the channels of the pump working bodies, intense wear of the lower impeller washer, melting of the extension cord and cable. Opening the check valve will occur only after the pressure on the pump outboard (under the shut-off device of the check valve) becomes higher than the pressure of the liquid column above it. Opening the check valve will occur only due to an increase in pressure at the pump intake due to inflow and increase in the dynamic level in the well. Such a transient negative process takes a long period of time (more than 10 hours).

If the check valve holder is equipped with a shut-off device in the check valve, the duration of the pump without feeding is reduced, since in the absence of supply the check valve does not close. And due to the increase in pressure at the pump intake due to the ongoing inflow into the well, the pump with an insignificant supply will pump formation fluid and free itself from the free gas plug. There will be no continuous heating of the pump, and the pump will become more durable. When the pump is turned off, the fluid flow passing through the holes 19 in the sludge trap 18, overpowering the spring of the retainer 15, puts the shut-off device 14 in the seat of the non-return valve.

Information sources

1. RF patent No. 2140575, IPC F04D 13/10, 16/16/1997. "Submersible centrifugal high-pressure electric pump for lifting liquids from wells."

Claims (1)

A submersible centrifugal high-pressure electric pump for lifting fluid from a well, containing a drain valve, a slurry pipe, sealed from above and having lower plugs, through radial openings, a check valve with a shut-off device, pump sections with an input module or gas separator and a submersible electric motor with hydraulic protection, connected in series and installed on the tubing string, characterized in that the check valve has a spring retainer of the locking device in the open position.

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