RU2544930C1 - Return valve of electric centrifugal unit and cleaning method of filter at pump suction - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: valve includes a body with the upper and lower connection threads, valve saddle fixed rigidly inside the body, thrust bush and washer with central and peripheral openings fixed in body by a locking ring, disc valve with rod passing through the central opening of washer, driving washer and spring installed between washer and driving washer. The rod of disc valve is made hollow with horizontal openings in the upper section connecting the tubing area over the valve with the area below the valve. The driving washer is a stepped one, and its lower part with less diameter forms a sliding friction couple with outer surface of the hollow valve rod. In the upper part of the driving washer with screwed cover and centralisers there are horizontal openings with diameter larger than diameter of openings in the valve rod. In the upper part of the valve rod from outside there is a locking ring and O-rings of elastic material, which are placed at both sides of horizontal openings in the valve rod.

EFFECT: improved efficiency of filter cleaning.

2 cl, 3 dwg

Description

The invention relates to the oil industry and can be used to flush the intake and cavity of electric centrifugal pumps from suspended solids of sand, asphalt-resinous substances and salts.

It is known that at the outlet of the electric centrifugal pump (ESP) in the tubing, check valves and drain valves are installed. When the pump stops, the non-return valve prevents the liquid from spilling out of the tubing into the well and unscrewing the pump shaft in the opposite direction. The drain valve allows, on the contrary, to release the tubing from the liquid for lifting equipment during repair (A. Bogdanov, Submersible centrifugal electric pumps for oil production. M: Nedra. 1968. P. 52-54). The liquid is poured from the tubing into the well by dumping the cargo into the tubing, which, having reached the drain valve, breaks it and forms a hole connecting the tubing cavity to the annulus.

A well-known valve of a borehole centrifugal pump (patent RU 72268 U1, application form. 26.12.2007, publ. 10.04.2008), comprising a housing with internal and external connecting threads and a saddle fixed in it and a ball locking element located in the channel of the axial displacement limiter. The valve seat is equipped with a seating groove under the o-ring and is fixed relative to the housing by a cylindrical sleeve and a washer with holes for the passage of formation fluid. In the upper part of the valve body there is a pipe with a sludge trap screwed into it, equipped with radial holes for the passage of formation fluid. A washer with holes for the passage of formation fluid is fixed from axial movement relative to the valve body by means of a spring ring, and the nozzle is mounted in the body by means of a key with a spring ring.

In addition, a check valve is known (patent RU No. 56940 U1, application form 04/07/2006, publ. 09/27/2006), consisting of a housing, a saddle fixed in the housing, a locking element in the form of a ball. A cylindrical channel and a limiter for the axial movement of the locking element in the channel with openings for the fluid flow are formed in the housing, the limiter being made integrally with the housing. The axis of the holes for the fluid duct are located on the generatrices of the cylindrical channel. The saddle is fixed at the inlet with a nut and / or threaded sleeve with keyways.

A common drawback of the above analogues is the inability to flush the ESP during clogging of the receiving part, as well as the injection of various chemicals through the pump into the well.

A well-known well filter being cleaned (patent RU 2441139 C1, application form 12.07.2010, publ. 01/27/2012), including the outer and inner pipes with openings, a filter element fixed between the pipes, a wave converter. The filter element is made in the form of twisted wire height. The wave converter is made in the form of a compression spring.

To clean the filter after clogging, the centrifugal pump is stopped and then started in the opposite direction of rotation of the rotor. A reverse fluid stream flushes adhering sand particles from the filter element.

The specified device has the disadvantage of the impossibility of creating a reverse fluid flow from the tubing through the pump to the well if there is a check valve at the outlet of the centrifugal pump.

Known automatic check valve, consisting of a housing with a seat on which a poppet valve with a stem is mounted (patent RU 2038463 C1. Automatic check valve. Claim. 03/17/1992. Publish. 06/27/1995). The rod is passed through an opening in the crosspiece installed in the housing. A spring is installed between the washer and the spider. On the side of the washer, a sleeve is mounted on the stem. At certain stopper pressures, the stem is jammed, allowing the turbodrill to be cleaned. The disadvantage of this valve is the dependence of the opening or closing of the shut-off element on the pressure and flow rate of the liquid, which is unacceptable for the operation of a submersible pump.

Closest to the invention in technical essence and the achieved result is a three-way check valve (patent RU No. 104618 U1, application. January 25, 2011, publ. 05/20/2011), which contains a housing with upper and lower connecting threads. The valve body is made integral and has upper, middle and lower parts. The hollow stem is fixed inside the housing motionless, the upper part of the stem is made in the form of a seat for the valve, and under the seat on it there are through radial channels. The movable element of the three-position check valve is a hollow piston located on the outer generatrix of the hollow rod coaxially with it with the ability to overlap and open the radial channels of the hollow rod. The movable hollow piston is spring-loaded and has two shoulders, which are a clamp for the movement of the piston vertically at a certain pressure on the piston.

The disadvantages of the selected prototype are the need for an additional increase in fluid pressure in the tubing, calculated in tens of atmospheres, which increases the risk of an emergency, the presence of two friction surfaces of the hollow movable piston (internal and external), which leads to its jamming, the possibility of accumulation of dirt above the piston, which also leads to jamming friction pairs.

An object of the invention is to provide filter cleaning without additional pressure buildup in the tubing string.

The problem is solved in that in the known device, comprising a housing with upper and lower connecting threads, a valve seat fixed fixed inside the housing, a thrust sleeve and a washer with central and peripheral holes fixed in the housing using a locking ring, a poppet valve with a stem passing through the central hole of the washer, the movable sleeve and the spring installed between the washer and the movable sleeve, according to the invention, the poppet valve stem is hollow with horizontal with holes in the upper part connecting the over-valve area of the tubing with the sub-valve, and the movable sleeve is stepped, the lower part of which with a smaller diameter forms a sliding friction pair with the outer surface of the hollow valve stem, and horizontal holes of a larger compared with the holes of the valve stem diameter, and in the upper part of the valve stem externally mounted circlip and o-rings made of elastic material located on the sides of the horizontal holes of the valve stem.

The solution to this problem was achieved in the method of cleaning the filter at the pump intake without lifting the submersible equipment to the surface by backwashing the filter element with liquid from the tubing string, including stopping the pump for repair, according to the invention, washing is carried out by lowering the load into the tubing string on the scraper wire through the lubricator at the wellhead, which compresses the spring with its own weight and moves the step-shaped movable sleeve downward, combining horizontal holes in the sliding sleeve and the hollow stem of the poppet valve and creating a flow of liquid under pressure from the tubing string into the well through the pump cavity and filter, and after washing the filter, the load is removed from the well and the pump is put into operation.

In fig. 1, 2, and 3, check valve diagrams are shown at various positions. In the valve body 1, installed above the pump, a seat seat 2 of the poppet valve 3 is placed, which passes into the hollow stem with horizontal holes in the upper part. Above the seat 2 are the thrust sleeve 4 and the washer 5 with central channels for the hollow rod and peripheral channels for the fluid flow. Above the washer there is a spring 6, which supports a movable sleeve 7 of a stepped form, closed on top by a cover 8 and having centralizers 9. In the sleeve 7 horizontal holes of larger diameter are also made. The valve 3 for a tight fit in the seat 2 has an elastic sleeve 10. To seal the friction pair: sleeve 7 is the hollow stem of the valve 3, the last one has elastic sleeves 11. To limit the vertical stroke of the sleeve 7, a snap ring 12 is placed on the hollow stem of the valve 3. fixing the liner 4 and the washer in the housing 1 also has a circlip 13. For operation of the valve, a load of 14 is used, which is lowered into the tubing string on the scraper wire through a lubricator (not shown).

The operation of the valve is as follows.

After the electric centrifugal pump is lowered into the well, the check valve 3, under its own weight, assumes the lowest position indicated in Fig. 1. At the same time, the spring 6 remains in the fully expanded position, in which the horizontal holes in the sleeve 7 and the hollow valve stem 3 do not match, which prevents the flow of fluid from the tubing to the pump.

When the pump starts to work under the action of a liquid pressure from below, valve 3 rises and passes the fluid into the tubing through the peripheral channels of the washer 5 (Fig. 2). Raising the valve 3 will cause the movable sleeve 7 to fall under its own weight relative to the stem, and the horizontal holes of the sleeve and hollow stem will coincide. Spring 6 is the same as in the case indicated in Fig. 1 remains unclenched. Thus, part of the produced fluid from the pump to the tubing will also flow through the hollow valve stem 3.

To clean the filter at the pump inlet from adhering mechanical impurities, it is stopped. Valve 3, under its own weight, will go down and press hydrostatic pressure from above to seat 2 (see Fig. 1). The spring 6 will return the sleeve 7 to its highest position, in which the holes in the sleeve 7 and the hollow stem of the valve 3 do not match, which will prevent the flow of fluid from the tubing into the pump.

Then, in the tubing of the well, a load 14 is lowered through the lubricator on the scraper wire, which, due to the weight exceeding the spring force of the spring 6, compresses it and moves the sleeve 7 down to the position indicated in Fig. 3. In this case, the holes in the sleeve 7 and the hollow stem of the valve 3 will coincide and the liquid from the tubing under high pressure will flow into the well through the pump cavity and the intake filter from its opposite side. Backwashing with filter fluid will allow it to wash away any adhering dirt. After a certain time, the load 14 is lifted and the sleeve 7 under the action of the compressed spring 6 will return to its highest position, at which the flow of fluid from the tubing to the well stops. Subsequently, the load 14 is removed from the well.

The cleaning time of the receiving part of the pump is selected with the calculation of the prevention of liquid reaching a static level in the well, at which repression to the formation is already being created.

After the flushing operation, the pump is started up.

The technical and economic advantages of the proposed device and method are the simplicity and reliability of its operation, as well as the absence of the need to raise the pressure in the tubing by a significant amount for flushing the pump and filter. In addition, the non-return valve can simultaneously serve as a drain valve, which simplifies tripping during well repair. Before lifting the underground equipment, in case of repair work, cargo 14 is discharged into the tubing without scraper wire. The dumped cargo, reaching the valve, will hit the cover 8, compress the spring 6 and hold the sleeve 7 in the lowest position relative to the hollow valve stem and allow fluid from the tubing to flow out of the tubing and the hollow stem into the well when lifting the equipment in repair period.

Claims (2)

1. The check valve of the electric centrifugal installation, comprising a housing with upper and lower connecting threads, a valve seat fixed motionless inside the housing, a thrust sleeve and a washer with central and peripheral holes fixed in the housing using a snap ring, a poppet valve with a stem passing through the central hole of the washer, the movable sleeve and a spring installed between the washer and the movable sleeve, characterized in that the poppet of the poppet valve is hollow with horizontal holes in the upper part connecting the tubular region of the tubing to the subvalvular, and the movable sleeve is stepped, the lower part of which with a smaller diameter forms a sliding friction pair with the outer surface of the hollow valve stem, and the horizontal holes of the upper part of the sleeve with a screwed cap and centralizers are larger than holes of the valve stem diameter, and in the upper part of the valve stem externally mounted circlip and o-rings of elastic material located on both sides of horizontal valve stem bores. 2. A method of cleaning the filter at the pump intake without lifting the submersible equipment to the surface by backwashing the filter element with liquid from the tubing string, including stopping the pump for repairs, characterized in that the washing is carried out by lowering the load into the tubing string on the scraper wire through the lubricator to wellhead, which compresses the spring with its own weight and moves the movable sleeve of a stepped shape downward, combining horizontal holes in the movable sleeve and hollow poppet of the valve and creating a fluid flow under pressure from the column of tubing into the well through the pump cavity and a filter, and the filter after washing load is removed from the well and the pump is started to work.

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