RU2787438C1 - Filter inlet module of submersible electric centrofugal pump - Google Patents

Abstract

FIELD: petroleum engineering.

SUBSTANCE: invention relates to petroleum engineering and can be used in the design of submersible electric submersible pumps for receiving and cleaning the produced product from mechanical impurities. The filter is an inlet module of a submersible electric centrifugal pump, containing a housing in the form of a cylindrical perforated pipe with threaded ends, while the threaded ends are made with the possibility of threaded connection at the upper end of the housing with a head, and at the lower end of the housing with a sub or base, while the head, sub and the base contains a bearing assembly of the shaft, made in such a way that in the installed state the bearing assembly is located outside the boundaries of the housing, while a filter is hermetically installed on the housing, including a filter element containing corrugation.

EFFECT: increasing the efficiency of both the operation of the filter of the input module, and the cleaning of the produced production of wells equipped with installations of submersible electric centrifugal pumps with a decrease in the outer diameter of the module.

17 cl, 2 dwg

Description

Technical field

The invention relates to oil engineering and can be used in the design of submersible electric centrifugal pumps for receiving and cleaning the produced product from mechanical impurities, as well as connecting the hydraulic protection and the pump section with the transmission of torque from the hydraulic protection shaft to the shaft of the pump section.

State of the art

Filter inlet modules are widely used to protect submersible centrifugal pumps from mechanical impurities contained in the extracted fluids. The designs of existing modules are known, for example, from RF patents No. 120999, No. 185867, No. 186587, No. 2551596, No. 189152, No. 144286.

In these devices, the filter element consists of at least one block of autonomous replaceable annular filter sleeves, and wire non-woven material, or "metal rubber", or pressed metal tangle, or porous permeable material, is taken as the filter material, the modules are equipped with a centralizer and a device for optimal compression of the filter element in the axial direction, as well as at least one central and two peripheral plain bearings fixed in the axial direction between the shaft and the inner surface of the housing, can be equipped with a bypass valve.

The disadvantage of these devices is the limited filtration area of the side surface of the filter sleeves, which leads to a low filter life as a result of rapid clogging of the filtration channels or an increase in manufacturing cost with a decrease in reliability due to the need to increase the length of the filter and module to maintain throughput, which is especially critical for wells. with production strings of small diameter, having a nominal diameter of 114 mm or less and a large curvature of the wellbore.

In addition, the disadvantage of these devices is the location of the bearings inside the housing with the filter element, which also limits the reduction in the size of the module without reducing the throughput.

The disadvantage of these devices is also the impossibility to provide a constant fineness of filtration over the entire area of the filter element, due to the use of independent replaceable annular filter sleeves and a device for compressing the filter element in the axial direction. Compression occurs unevenly both along the block of bushings and along the length of the bushings themselves, which cannot provide a constant fineness of filtration, respectively, reduces the filter life due to premature clogging or does not provide the necessary filtration of the produced fluid.

A block of autonomous replaceable annular filter inserts complicates the process of assembly and revision of the module, requires the use of special bench equipment for their revision and flushing during service maintenance, which increases time and resources.

The essence of the invention

The objective of the invention is to eliminate the disadvantages of the prior art, namely the increase in the specific area of filtration, while without increasing the length of the filter input module.

The technical result of the invention is to increase the efficiency of both the operation of the filtering input module and the cleaning of the produced production of wells equipped with installations of submersible electric centrifugal pumps with a decrease in the outer diameter of the module.

The present problem is solved, and the technical result is achieved using the proposed filter input module of a submersible electric centrifugal pump. The filtering inlet module according to the present invention contains a body in the form of a cylindrical perforated pipe with threaded ends, while the threaded ends are made with the possibility of threaded connection at the upper end of the body with a head, and at the lower end of the body with a sub or base, while the head, sub and base contain a bearing assembly of the shaft, made in such a way that in the installed state the bearing assembly is located outside the boundaries of the housing, while a filter containing a filter element made of a material containing corrugation is hermetically installed on the housing.

The filter contains an inner perforated casing and an outer perforated casing, between which the filter element is located.

The pleated material of the filter element is a mesh permeable material, or a bulky wire permeable material, or a porous permeable material.

The corrugated material is subjected to longitudinal, radial or helical corrugation.

The tightness of the installation of the filter on the housing is provided with plugs with sealing rings.

The head, sub, and base have an outer diameter of the threaded portions substantially the same as the outer diameter of the filter.

The inner surface of the head and the inner surface of the sub contain a recess relative to the threaded section under the body, while the shaft bearing assembly is located at the level of the recess.

The bearing assembly contains a number of circumferential holes, while the diameter and number of circumferential holes are calculated so that the bore area of the bearing assembly is at least 90% of the bore area of the annular channel formed in the housing.

The base contains at least one safety valve.

The material of the inner perforated casing is a steel pipe, on the side surface of which through holes are made, or a slotted frame-wire structure, or a metal mesh.

The material of the outer perforated casing is a steel pipe on the side surface of which through holes are made, or a slotted frame-wire structure, or a metal mesh.

Brief description of the drawings

Fig. 1 - longitudinal section of the filter input module;

Fig. 2 is a cross section of a longitudinally pleated filter element.

Detailed description of the invention

The filtering inlet module consists of a housing 1 made in the form of a cylindrical perforated pipe with threaded ends with an external thread. Filter 2 is installed on housing 1. The tightness of the connection between filter 2 and housing 1 is ensured by sealing rings 3.

In the case of using one filter as part of the filtering input module, head 4 and base 5 are screwed onto the threaded ends of housing 1, holding filter 2 from axial movement. Shaft 6 is mounted in head 4 and base 5 by means of plain bearings 7.

If two or more filters are used as part of the filtering input module, each filter 2 is installed on a separate housing 1, the head 4 is screwed onto the first housing in the upper part, and the base 5 is wound onto the lower part of the last housing 1. Filter housings 1 2 between the first and the last housings are interconnected by sub 8, with an intermediate plain bearing 9. In this case, the first filter 2 from above is kept from axial movement from above by head 4, from below by sub 8. The last, lowest filter 2 is kept from axial movement from above by sub 8, from below by base 4 The remaining filters 2 are kept from axial movement by subs 8.

Bearings 7 and 9 in the assembled state of the filter input module are located outside the boundaries of the filter housing. This arrangement makes it possible to reduce the outer diameter of the filter inlet module. Bearings 7 and 9 are radial plain bearings, made in the form of two bushings, outer and inner, made of wear-resistant material. The inner sleeve is mounted on the shaft 6 with a key, the outer one is pressed into a cylindrical groove in the body of the head 4, base 5, sub 8.

In order not to reduce the effective filtration area with a decrease in the filter diameter, the filter element is made pleated.

Side holes 10 are made in the body 1. Circular rows of holes 11 are made in the head 4 and the sub 8. An annular through passage 12 is formed between the shaft 6 and the body 1. The diameter and number of holes 11 are design values that are calculated in such a way as to provide a flow area , the area of which is at least 90% of the area of the flow section of the annular channel in the housing 1. This ratio ensures that the flow rate is maintained to ensure the pump performance at the nominal level, even taking into account the small diameter of the annular channel of the housing 1 and the narrowing of the flow area in the bearing area. The specified flow area of the circumferential holes is provided by the design of the head and sub, the internal space of which is expanded at the level of the bearing relative to the internal space of their threaded sections, that is, the internal surfaces of the head and adapter contain recesses relative to the threaded sections. This implementation allows to reduce the outer diameter of the module without loss of pump performance. In addition, this arrangement provides better heat dissipation from the bearings, which increases reliability and service life.

Due to the fact that the thread on the body 1 is made external, the flow area of the annular channel remains constant, that is, does not narrow in the area of the threaded ends, which is advantageous in conditions of small diameter of the annular channel.

Filter 2 consists of an inner perforated casing 13 and an outer perforated casing 14, between which a filter element 15 is installed. Filter 2 is hermetically sealed from above and below by plugs 16.

To reduce damage during tripping operations (TRH), the outer surfaces of the elements of the filter input module are located essentially flush, which is especially important when tripping in small diameter wells.

The filter element 15 is a mesh permeable material, or a bulk wire permeable material, or a porous permeable material subjected to corrugation, longitudinal, radial or helical. The filter element is generally made in the form of a hollow element of a permeable material in the form of a body of revolution, for example, a truncated cone or cylinder. The corrugation can be performed on a section of the material of the hollow element or along its entire length. Corrugation can be longitudinal, radial or helical.

Figure 2 shows an example of a cross section of a cylindrical filter element with longitudinal corrugation along the entire length of the filter element material.

As can be seen from this figure, the filter element is made in the form of filter curtains containing corrugations, the free space between which acts like a slotted longitudinal gap: between the tops of the corrugations, a rough cleaning of the liquid from large mechanical particles occurs, with a size exceeding the distance between the tops of the filter curtains. With further operation of the pump, a pre-filter of fine particles is formed. After coarse cleaning, after passing through the pre-filter, the fluid passes through the filter curtains, where it undergoes one-, two- or multi-stage "fine" purification from mechanical impurities, depending on the design of the corrugated curtain, which can consist of one, two or more layers of permeable material , including the coarser filter layer(s) used to stiffen the filter element, both externally and internally.

The coarse filtration layer can be located both on the outside of the filter element and on the inside, and in addition, the coarse filtration layer can also be placed as an intermediate layer.

The filter element may contain several layers of coarse filtration in a different order. The coarse filtration layer has a filtration fineness that exceeds the filtration fineness of the filter element layer with the smallest filtration fineness by two or more times.

The coarse filtration layer can be located both on the outside of the filter element and on the inside, and, in addition, it is possible to place the coarse filtration layer as an intermediate layer. The filter element may contain several layers of coarse filtration in a different order.

In multilayer filter elements, each layer can have either the same filtration fineness or a different filtration fineness. Thus, fine cleaning can be single or multi-stage.

The pleated design of the filter element, among other things, allows for a longer filter life, as it does not allow large particles to settle on the filter, which would lead to rapid clogging of the pores. Tests show that large particles are ricocheted from the tops of the filter curtain without passing into the gap between the corrugations. Particles with a size within the size of the gap can get stuck in the slit gaps, contributing to the formation of the pre-filter. Due to its arbitrary shape, the coarse particle does not completely clog the pores of the filter material and fluid passageways, the so-called pore spaces, remain in it. Over time, such particles become clogged along the entire length of the slot, forming a pre-filter. Smaller particles are retained in the pore space of large particles, and then even the smallest particles are trapped in the pore space of larger particles, creating a so-called "bridge" that forms a prefilter.

Studies have established that a "bridge" of small mechanical particles is formed when the particle diameter is 2 to 5 times smaller than the size of the filtration holes, i.e. from 2 to 5 times less than the fineness of filtration.

The authors found that in order to facilitate the creation of such a pre-filter, it is necessary to satisfy the condition under which t ≤ 2S + 5*TF, where t is the pleating step; S is the thickness of the filter element; TF is the filtration fineness of the filter element.

This condition is necessary to exclude the formation of a pre-filter from mechanical particles, the size of which will be comparable to the size of the filtration fineness on the side surface formed by the tops of the corrugations, otherwise the filtration area decreases many times, becomes comparable to the surface area formed by the tops of the corrugations.

Thus, due to the presence of corrugation with the specified characteristics, the filter element allows you to increase the time between failures.

The corrugation coefficient, which is the ratio of the length of the material or material section to be corrugated before corrugation to the length of this material or material section after corrugation, affects the number of corrugations. The value of the pleating factor must be at least 2, otherwise the filtration area may be reduced. In addition, the more corrugations, the more resistant the design to sagging over time and to wall deflection during pump operation.

When the pump is in suction mode, the pleated filter element is subject to deflection in the direction of liquid flow. The pre-filter, which is formed in the gap between the corrugations narrowed due to the deflection, effectively disintegrates when the filter element returns to its original position at the end of the pump, contributing to self-cleaning.

The regeneration of such a filter element is improved by a design capable of expanding under the pressure of a liquid backflow. The slotted channels, expanding, allow the clogging accumulated after rough cleaning to be released. Rinsing is faster and more efficient.

In a particular case, the filter element is completely pleated, that is, the pleating is made over the entire surface of the filter element.

In a particular embodiment, the filter element is partially corrugated, i.e. the corrugation is made only on a part of the surface of the filter element.

In a particular case, the filter element contains at least two layers of permeable material, one of which is completely or partially corrugated.

Additionally, at least one safety valve 17 can be installed in the base 5, which opens at a given pressure drop in case of filter 2 clogging.

The required number of safety valves is calculated by the formula:

N \u003d Q _N / q _cl ,

where Q _N is the rated performance of the pump;

q _cl - nominal flow through one valve, which is determined by the formula:

q _cl \u003d C * Δp,

where C is the capacity of the valve;

Δp is the hydraulic pressure loss in the valve.

The safety valve actuation pressure (Р _СК ) is selected from the condition:

R _PNM > R _SK < 0.5*R _RF ,

where P_{PNM -}minimum back pressure of a submersible electric centrifugal pumping unit;

Р _RF - excess pressure at which the filter element will be destroyed.

The flow capacity for the selected safety valve size is determined from the hydraulic characteristics, which are obtained from the results of bench tests of the valve, as the dependence of hydraulic pressure losses on the capacity.

If it is necessary to protect the produced well product from a high gas factor, the filtering inlet module can be additionally equipped with a gas separating and/or dispersing unit.

The filter input module of the submersible electric centrifugal pump works as follows:

After turning on the pumping unit, the fluid medium passes through the holes of the outer casing 14 and the pleated filter element 15, and is filtered from mechanical impurities. Further, the purified fluid passes through the holes of the inner casing 13, side channels 10 of the body 1, enters the intake of the ESP pump sections, moving along the annular channel 12 and through the circumferential rows of holes 11. At the same time, the safety valve 17 is closed.

When the filter element is clogged with particles of mechanical impurities, the liquid pressure drop between the pressure outside and the pressure in the internal cavity of the filter increases. At the same time, under the action of the fluid pressure drop, the safety valve 17 opens. Formation fluid through the opening of the passage channel of the safety valve 17 from the annulus passes into the filter, moving along the annular channel 12 and the circumferential rows of holes 11 enters the intake of the pumping sections of the ESP, excluding the stall of the pump and failure of the ESP installation as a whole.

Claims (17)

1. The filtering input module of a submersible electric centrifugal pump in the form of a cylindrical perforated pipe with threaded ends, while the threaded ends are made with the possibility of a threaded connection at the upper end of the housing with a head, and at the lower end of the housing with a sub or base, while the head, sub and base contain a bearing assembly of the shaft, made in such a way that in the installed state the bearing assembly is located outside the boundaries of the housing, while a filter is hermetically installed on the housing, including a filter element containing pleats. 2. The filter inlet module according to claim 1, in which the filter comprises an inner perforated casing and an outer perforated casing, between which the filter element is located. 3. The filter inlet module of claim 1, wherein the filter element material is a mesh permeable material, or a bulk wire permeable material, or a porous permeable material. 4. The filter input module according to claim 1, wherein the pleating is longitudinal. 5. The filter inlet module of claim 1, wherein the pleats are radial or helical. 6. The filter input module according to claim 1, in which the tightness of the installation of the filter on the housing is provided with plugs with sealing rings. 7. The filter inlet module of claim 1, wherein the threaded ends of the housing comprise an external thread. 8. The filter input module according to claim 1, in which the inner surface of the head and the inner surface of the sub contain a recess relative to the threaded section under the body, while the shaft bearing assembly is located at the level of the recess. 9. The filter input module according to claim 1, in which the bearing assembly contains a number of circumferential holes, while the diameter and number of circumferential holes are calculated so that the bore area of the bearing assembly is at least 90% of the bore area of the annular channel formed in the housing. 10. The filter inlet module of claim 1, wherein the base includes at least one safety valve. 11. The filter input module according to claim 2, in which the inner perforated casing is a steel pipe, on the side surface of which through holes are made, or a slotted frame-wire structure, or a metal mesh. 12. The filter input module according to claim 2, in which the outer perforated casing is a steel pipe, on the side surface of which through holes are made, or a slotted frame-wire structure, or a metal mesh. 13. The filter inlet module of claim 1, wherein the filter element comprises at least one layer of permeable material. 14. The filter input module of claim 13, wherein the filter element comprises at least two layers, the layers having the same or different filtration ratings. 15. The filter input module of claim 14, wherein the filter element comprises at least one coarse filter layer. 16. An inlet filtering device containing a filtering inlet module according to claim 1 and a gas separating unit. 17. Inlet filtering device containing the filtering input module according to claim 1 and a dispersing assembly.

Images