RU2709580C1 - Slit-type filter - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry and can be used for protection of well pump installations during oil production in conditions complicated by high content of mechanical impurities in formation fluid. Proposed device comprises pipe with filtration section with holes perforations and slots for moving said two-sided thrust. Around the pipe there is a filter element concentrically installed, which is made in the form of a wire wound along a spiral, between the coils of which there formed are slots. Size of slits is adjusted by means of spring, which force exceeds elastic deformation of filtering element wire. Upper and lower stationary stops are mounted on pipe ends, and stiffening ribs are installed on outer surface of filter section. Filter is additionally equipped with elastic element with through holes, channels or cavities, which is fixed on movable double-sided support. Filter element is arranged between movable double-sided and upper fixed stops with rigid end of wire turns. Spring is located between double-sided and lower fixed stops.

EFFECT: higher convenience of maintenance and efficiency of slit-type filter operation in the well due to reduced time for its cleaning and, consequently, increased operating time of the downhole pump unit for failure.

4 cl, 5 dwg

Description

The invention relates to the oil industry and can be used to protect well pump installations during oil production under conditions complicated by a high content of solids in the reservoir fluid.

A device is known, which is a downhole slit filter, including a filter element, drive and driven shafts, interconnected by means of a gearbox, a blade and cleaning elements mounted on a driven shaft. The driven shaft is surrounded by a filter element, the lower end of which is open, and the upper end is closed by a cover through which the driven shaft passes. On the drive shaft is a blade enclosed in a housing with inlet openings at the bottom and outlet openings at the top. O-rings are mounted on the housing above the inlets and on the lower end of the filter element. The cleaning elements interact with the filter element during rotation of the driven shaft, thereby cleaning it during operation in the well. The device is intended for long-term protection of electric centrifugal pumps from ingress of mechanical impurities [US Pat. RU 2618248 C1, IPC Е21В 43/08, publ. 05/03/2017].

The disadvantages of the known device include the fact that its scope is limited to borehole pumping units having submersible motors with two-way output of rotating drive shafts. The device has a complex structure, which includes a gearbox. The contact of the filter element with cleaning elements made in the form of rack brushes or spring-loaded strikers causes accelerated wear of the latter, which reduces the resource of the device as a whole.

Closest to the claimed device, by a combination of features, there is a slit filter containing a pipe, the filter section of which has perforations in the form of holes, a filter element in the form of a spiral wound wire with the formation of gaps between the turns, and a spring. The filter element is located concentrically to the pipe between the fixedly fixed lower stop in the form of a cup and the movable bilateral stop and is installed in the annular gaps between the outer diameter of the pipe and the inner diameters of the lower stop and the movable bilateral stop, with the end ends of the wire resting on the annular area of each of the stops. Between the movable bilateral emphasis and the upper motionlessly fixed emphasis, a spring is installed, the initial force of which exceeds the elastic deformation of the wire of the filter element, which ensures a snug fit of the turns of the wire of the filter element [US Pat. RU 2445146 C1, IPC B01D 29/48, publ. 03/20/2012].

During operation of the described slotted filter, the liquid to be cleaned passes through the slots of the filter element, and the particles of mechanical impurities contained in it are retained on the surface of the filter element, reducing its throughput over time. To clean the filter element from deposits, a backwash is carried out, in which the liquid is fed into the inner space of the perforated pipe section and enters the space between the outer wall of the pipe and the filter element, where it exerts hydraulic pressure on the movable double-sided stop, preloaded by the spring. There are forces exceeding the force of the spring pressing the filter element. The movable double-sided stop begins to move, the coils of the wound wire of the filter element stretch. As a result, the size of the slots between the turns increases and under the influence of the fluid flow the filter element is cleaned of mechanical impurities.

This device is adopted as a prototype.

The signs of the prototype, coinciding with the essential features of the claimed device for cleaning the produced fluid, are: the presence of a pipe containing a filter section with perforation in the form of holes; grooves to limit the mobility of the bilateral emphasis mounted concentrically to the pipe of the filter element in the form of a spiral wound wire with slots between the turns; motionless and mobile bilateral emphasis; spring, the force of which exceeds the elastic deformation of the wire of the filter element.

The disadvantages of the known device include the fact that cleaning the filter element requires a backwash of the filter, which is difficult, and often impossible, to carry out in oil wells. The pump installation must be stopped and raised from the well to clean the filter, which entails significant time and material costs.

The tasks to which the invention is directed are: improving the serviceability and efficiency of the slit filter in the well by reducing the time to clean it and, as a result, increasing the time between the well pump installation for failure.

This result is achieved by the fact that in the slotted filter, including a pipe with a filter section with perforation in the form of holes and grooves to limit the movement of the movable two-sided stop, a filter element installed concentrically to the pipe in the form of a spiral-wound wire with slots between the turns, the upper and lower stops, a spring whose force exceeds the elastic deformation of the wire of the filter element, according to the invention, an elastic element with through holes in the channel is fixed on a two-way movable stop or cavities, the end turns of the wire of the filter element are rigidly connected to the stops, and stiffeners are installed on the outer surface of the filter section of the pipe.

When using a slotted filter as an input filter, a drive shaft is additionally passed through the pipe, which is installed in the bearing units.

The use in the design of the proposed device of an elastic element mounted on a two-sided movable stop allows mechanical cleaning of the filter element when operating as part of a downhole pumping unit. Due to the friction of the elastic element against the walls of the production casing of the well, the filter element is deformed, the gaps between the turns of the wires increase. In this case, the mechanical cleaning of the filter element can be carried out directly in the well without removing the installation from it, which eliminates the cost of tripping and long-term shutdown of the production of well fluid. The presence of through holes, channels or cavities in the elastic element ensures the unhindered entry of the borehole fluid to the filter element and the removal of particles of mechanical impurities in the sump of the well when cleaning the filter element.

A rigid connection of the end turns of the wire of the filter element with the movable and fixed stops ensures the deformation of the filter element when moving the movable stop and the increase of the cracks between the turns. Thanks to this, the filter element is cleaned of deposits of mechanical impurities and the restoration of its permeability.

The presence of stiffeners on the outer surface of the pipe helps to prevent deformation of the filter element during operation of the filter and to reduce the area of rubbing surfaces when cleaning the filter element. In addition, the presence of gaps between the pipe and the filter element created by stiffeners, ensures the cleaning of the well fluid the entire surface of the filter element.

Options for the manufacture of the inventive device as a downhole filter and an inlet filter of a downhole pump.

Based on the foregoing, the claimed filter is a technical solution, has novelty and has an inventive step, since it is unknown from the prior art and for specialists it does not explicitly follow from the prior art with an earlier priority. The industrial applicability of the slit filter is confirmed by the possibility of its implementation using well-known tools used in the oil industry and materials.

The essence of the device is illustrated by drawings, where in FIG. 1 shows a longitudinal section of the inventive slotted filter in the embodiment as a downhole filter with an elastic element in the form of a cuff.

In FIG. 2 shows a longitudinal section of the inventive slotted filter in an embodiment as an inlet filter of a well pump with an elastic element.

In FIG. 3 shows a longitudinal section of an elastic element in the form of a cuff with through holes.

In FIG. 4 shows a frontal projection of an elastic element in the form of a cuff with through holes.

In FIG. 5 shows a longitudinal section of the inventive slotted filter in the embodiment as an inlet filter of a well pump with an elastic element in the form of a centralizer with through cavities.

The slit filter (Fig. 1, 2) contains a pipe 1 with a filter section 2, on which perforation is made in the form of through holes 3 and stiffeners 4 are installed on the outer surface. At the ends around the pipe 1, the upper 5 and lower 6 are fixed stops, made in the form of glasses, between the inner surface of the walls of which and the outer surface of the pipe 1 are formed annular gaps. Around the pipe 1, a filter element 7 is arranged concentrically, made in the form of a spiral-wound wire 8, between the turns of which slots are formed 9. The filter element 7 is installed between the upper fixed stop 5 and the two-way movable stop 10, while the end turns of the spiral wire 8 of the filter element 7 placed inside the annular gaps are rigidly connected to the stops 5 and 10.

The bilateral movable stop 10 is able to axially move along the pipe 1, while the movement of the movable bilateral stop 10 is limited by the length of the grooves 11 made on the outer surface of the pipe 1, into which the ends of the screws 12 are recessed. On the lateral surface of the bilateral movable stop 10, for example, by screws 12 fixed elastic element, made, for example, in the form of a cuff 13 with through holes 14 (Fig. 3, 4). The cuff 13 can be made, for example, in the form of a truncated cone with through holes, or in the form of a disk with through holes or channels, or have a complex cross-sectional shape, in particular, a composite structure with separate petals and through cavities for unhindered passage of the well fluid to the filter element. The cuff 13 is in contact in the well with the walls of the production casing 15 (Fig. 1, 2). Between the lower fixed stop 6 and the two-sided movable stop 10 with support on their annular platforms, a spring 16 is installed, the force of which exceeds the elastic deformation of the wire of the filter element 7.

When using the inventive slotted filter as an input filter for a borehole pump (Fig. 2), bearing assemblies 17 are rigidly mounted inside the pipe 1, which serve as supports for the drive shaft 18 passing through them.

As an alternative to the elastic sleeve 13, a centralizer 19 (Fig. 5) may be used, formed, for example, by several curved metal plates 20, the upper ends of which are rigidly fixed to the outer surface of the movable stop 10, and the lower ends can freely move relative to the outer surface of the movable stop 10 with elastic deformation of the plates 20. Between the plates 20 of the centralizer 19, the outer surface of the movable stop 10 and the walls of the production casing 15, through cavities 21 are formed that allow passage of important fluid to the filter element 7. The curved surfaces of the plates 20 are in contact with the walls of the production string 15.

The inventive slit filter operates as follows.

The slotted filter as part of the submersible pump installation layout is lowered into the well. Downhole fluid containing mechanical impurities freely flows to the surface of the filter element 7 through the through holes 14 of the cuff 13 (Fig. 1, 2), or through the through cavities 21 of the centralizer 19 (Fig. 5). Passing between the slots 9 turns of a spirally wound wire 8 of the filter element 7, the borehole fluid is cleaned, and through the holes 3 of the filter section 2 feeds inside the pipe 1, which then goes up into the borehole pump (not shown).

Particles of mechanical impurities, separated from the well fluid, settle on the outer surface of the filter element 7, creating “bridges” of deposits and reducing its permeability (throughput) over time. The increasing pressure drop on the outer and inner surfaces of the filter element 7 leads to an increase in the load on the outer surface, but thanks to the stiffening ribs 4, deformation of the filter element 7 can be avoided. A spring 16 installed in the annular gap of the fixed stop 6 holds the filter element 7 and the two-sided stop 10 in a fixed initial state.

When the filter element 7 is clogged, the selection of the well fluid is stopped, disabling the drive of the well pump. The entire arrangement of the submersible pump unit is moved along the production casing 15 towards the wellhead by an amount equal to the length of 1-2 tubing. During the lifting, the elastic cuff 13 or the curved surfaces of the plates 20 of the centralizer 19 rub against the walls of the production casing 15, while the friction force is directed opposite to the force of the spring 16. As a result, the movable bilateral stop 10 with the elastic element fixed on it moves downward along the grooves 11, compressing spring 16 and stretching the wire of the filter element 7 along the stiffeners 4.

The increase in the slots 9 between the turns of the wire 8 contributes to the destruction of the "bridges" of deposits of mechanical impurities and the restoration of the permeability of the filter element 7. Thus, the mechanical cleaning of the inventive slotted filter.

Particles of mechanical impurities separated from the surface of the filter element 7 through holes 14 in the cuff 13 or through the through cavities 21 of the centralizer 19 are deposited in the sump of the well.

To return to its former place, the layout of the submersible pump unit is moved along the production casing 15 towards the bottom of the well by an amount equal to the length of 1-2 tubing, while the direction of the friction force generated by the contact of the walls of the production casing 15 and the elastic element 13 or 19. Under the action of the spring 16, the movable stop 10 moves upward in the slots 11 and compresses the coils of the wire 8 of the filter element 7, restoring the original size of the slots 9 between the coils 8, after which the eyes enny slotted filter is ready for further use.

Thus, due to the periodic mechanical cleaning of the filter element, the operating time of the slit filter in the well increases and the MTBF of the well pump installation increases.

Claims (4)

1. A slit filter containing a pipe having a filter section with perforations in the form of holes and grooves for moving a movable bilateral stop, a filter element mounted concentrically to the pipe in the form of a spiral wound wire with the formation of slots between the turns, regulated by a spring, the force of which exceeds the elastic deformation filter element wires, fixed upper and lower stops, characterized in that it is additionally equipped with an elastic element with through holes, channels or cavities which is mounted on a movable bilateral stop, the filter element is placed between the movable bilateral and upper fixed stops with rigid attachment of end turns of wire to them, and the spring is located between the bilateral and lower fixed stops, with stiffening ribs installed on the outer surface of the filter section of the pipe. 2. The slotted filter according to claim 1, characterized in that a cuff is used as an elastic element. 3. The slit filter according to claim 1, characterized in that a centralizer with through cavities is used as an elastic element. 4. The slotted filter according to claim 1, characterized in that when used as an input filter, it further comprises bearing assemblies and a drive shaft mounted inside the pipe.

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