CN112282708A - Screen pipe, pipe string and unblocking method - Google Patents

Abstract

The invention discloses a sieve tube, a tubular column and a deblocking method, which relate to the field of oil and gas exploitation, and the sieve tube comprises: the base pipe is provided with a first opening on the side wall; the protective shell is sleeved outside the base pipe, a second opening is formed in the side wall of the protective shell, and an annular accommodating cavity is formed between the base pipe and the protective shell; and a pre-filled particle unit filled in the accommodating cavity, wherein the volume of the pre-filled particle unit can be changed to be reduced when a preset condition is met. This application can realize that the screen pipe blocks up the back from the function of deblocking, guarantees the oil well productivity.

Description

Screen pipe, pipe string and unblocking method

Technical Field

The invention relates to the field of oil and gas exploitation, in particular to a sieve tube, a tubular column and a deblocking method.

Background

In China, loose sandstone reservoirs occupy an important position, for example, a victory oil field in the Bohai region, a Liaohe oil field, a hong kong oil field, a Bohai oil field, a Jidong oil field and the like all have a large number of such reservoirs. Such reserves share some common features: shallow burial, weak cementing action and easy sand production in the mining process.

As an important sand control mode, the sand control of a mechanical sieve tube mainly comprises the following steps: slotted screens, premium screens, and prepacked screens, etc. Wherein: the high-quality sieve tube is suitable for homogeneous reservoirs and reservoirs with lower mud content, and has the defect that sand blocking media are easy to erode and damage, so that sand prevention is ineffective; the slotted screen pipe is simple to process and low in cost, but is easy to block, and due to the restriction of a processing technology, the sand prevention precision of the slotted screen pipe is limited, so that the slotted screen pipe is only suitable for reservoirs with coarse stratum sand granularity; the pre-filled sieve tube has the characteristics of partial gravel filling sand prevention mode, is simple to process and convenient to put in, is suitable for wells which are difficult to carry out gravel filling operation or have higher operation cost, such as long horizontal wells, overlong horizontal wells, highly-deviated wells and the like,

at present, from the field use condition, two main problems exist in the sand control process of the mechanical screen pipe: 1. on one hand, the screen pipe blockage is caused by sand control exploitation of the unconsolidated sandstone reservoir, the productivity is greatly reduced, the blockage mechanism of various screen pipes is not clear, and a reasonable solution for slowing down the screen pipe blockage is not found; 2. on the other hand, the partial blockage of the screen pipe can cause the reduction of the flow area of the screen pipe, and the pressure difference and the partial flow velocity are increased, so that the erosion damage to the screen pipe is generated, and the sand control failure of the screen pipe is caused, which is frequently seen in the current production process of offshore oil fields.

Disclosure of Invention

In order to overcome the defects in the prior art, the technical problem to be solved by the embodiment of the invention is to provide a screen pipe, a pipe column and a plug removing method, which can realize the function of self plug removal after the screen pipe is plugged, and ensure the productivity of an oil well.

The specific technical scheme of the embodiment of the invention is as follows:

a screen, the screen comprising:

the base pipe is provided with a first opening on the side wall;

the protective shell is sleeved outside the base pipe, a second opening is formed in the side wall of the protective shell, and an annular accommodating cavity is formed between the base pipe and the protective shell;

and a pre-filled particle unit filled in the accommodating cavity, wherein the volume of the pre-filled particle unit can be changed to be reduced when a preset condition is met.

Preferably, the pre-packed particle unit includes a base particle and a sensitive particle whose volume can be changed when a preset condition is satisfied.

Preferably, the density of the base particle is 0.95g/cm³To 1.05g/cm³In the meantime.

Preferably, the sensitive particles are pressure sensitive particles, and the volume of the pressure sensitive particles can be shrunk under the condition that the external pressure is increased, so that the gaps among the pre-filled particle units are gradually increased, and the self-unblocking is realized.

Preferably, the sensitive particles are meltable particles, and the meltable particles can dissolve or decompose under the action of temperature rise and flow out of the accommodating cavity along with formation fluid, so that the gaps among the pre-filled particle units are gradually increased, and self-unblocking is realized.

Preferably, the meltable particles start to dissolve when the ambient temperature reaches 80 ℃ or more, and the meltable particles use stearic acid or ice flower wax polymer.

Preferably, the sensitive particles are breakable particles, and the breakable particles are broken under the action of downhole pressure and mechanical pressure and flow out of the accommodating cavity along with formation fluid, so that gaps among the pre-filled particle units are gradually increased, and blockage removal is realized.

Preferably, the breakable particles start to break when the pressure of the underground environment reaches above 5Mpa, the breaking starting pressure is set according to the depth of the reservoir, and the breakable particles are hollow spherical substances.

A tubular string comprising a screen as claimed in any preceding claim.

A method of unplugging a screen using any of the above, the method comprising:

and (3) enabling the pre-filled particle units to reach a preset condition so that the volume of the pre-filled particle units is changed and reduced, and the inter-particle pores of the pre-filled particle units are increased, so that the sand bridge is damaged, and the self-plugging removal of the sieve tube is realized.

The technical scheme of the invention has the following remarkable beneficial effects:

the sieve tube in this application realizes playing the effect of stopping to the big sand grain of particle size through the hole between the granule in the prefilling granule unit, and the fluid that mixes with the sand grain passes through the second trompil of protective housing after the filtration of prefilling granule unit, during the first trompil inflow sieve tube of base pipe again. When the pores among the particles are blocked, the conditions of the pre-filled particle units in the sieve tube are changed to meet the preset conditions, so that the volume of the pre-filled particle units is changed and reduced, the pores among the particles in the pre-filled particle units are increased, the sand bridge is damaged, the self-blocking removal after the sieve tube is blocked is realized, the overflowing capacity of the sieve tube is maintained, and the productivity of the oil well is ensured.

Specific embodiments of the present invention are disclosed in detail with reference to the following description and drawings, indicating the manner in which the principles of the invention may be employed. It should be understood that the embodiments of the invention are not so limited in scope. Embodiments of the invention include many variations, modifications, and equivalents. Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.

Drawings

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. In addition, the shapes, the proportional sizes, and the like of the respective members in the drawings are merely schematic for facilitating the understanding of the present invention, and do not specifically limit the shapes, the proportional sizes, and the like of the respective members of the present invention. Those skilled in the art, having the benefit of the teachings of this invention, may choose from the various possible shapes and proportional sizes to implement the invention as a matter of case.

FIG. 1 is a schematic view of a screen according to an embodiment of the present invention, partially broken away;

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;

fig. 3 a-3 c are schematic diagrams of pre-packed particle units in an original state, a blocked state, and a self-unblocked state according to embodiments of the present invention.

Reference numerals of the above figures:

1. a base pipe; 11. a first opening; 2. a protective shell; 21. a second opening; 3. an accommodating chamber; 4. pre-packed particle units; 41. a base particle; 42. a sensitive particle; 5. an elastic mechanism; 6. and (4) sand grains.

Detailed Description

The details of the present invention can be more clearly understood in conjunction with the accompanying drawings and the description of the embodiments of the present invention. However, the specific embodiments of the present invention described herein are for the purpose of illustration only and are not to be construed as limiting the invention in any way. Any possible variations based on the present invention may be conceived by the skilled person in the light of the teachings of the present invention, and these should be considered to fall within the scope of the present invention. It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "mounted," "connected," and "connected" are to be construed broadly and may include, for example, mechanical or electrical connections, communications between two elements, direct connections, indirect connections through intermediaries, and the like. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In order to realize the self-plugging-removing function after the screen pipe is plugged and ensure the oil well production capacity, the present application provides a screen pipe, fig. 1 is a schematic structural diagram of the screen pipe in the embodiment of the present invention, fig. 2 is a cross-sectional view taken at a-a in fig. 1, and as shown in fig. 1 and fig. 2, the screen pipe may include: the base tube comprises a base tube 1, wherein a first opening 11 is formed in the side wall of the base tube 1; the protective shell 2 is sleeved outside the base tube 1, a second opening 21 is formed in the side wall of the protective shell 2, and an annular accommodating cavity 3 is formed between the base tube 1 and the protective shell 2; and a pre-filled particle unit 4 filled in the accommodating chamber 3, wherein the volume of the pre-filled particle unit 4 can be changed to be reduced when a preset condition is met.

The sieve tube in this application realizes playing the effect of stopping to the big sand grain 6 of particle size through the hole between the granule in the prefilling granule unit 4, and the fluid that mix with sand grain 6 passes through the second trompil 21 of protective housing 2 through the filtration of prefilling granule unit 4 after, in 11 inflow sieve tubes of first trompil of base pipe 1 again. When the pores among the particles are blocked, the conditions of the pre-filled particle units 4 in the sieve tube are changed to meet the preset conditions, so that the volume of the pre-filled particle units 4 is changed and reduced, the pores among the particles in the pre-filled particle units 4 are increased, sand bridges are damaged, the sieve tube is automatically unblocked after being blocked, the flow capacity of the sieve tube is maintained, and the productivity of an oil well is ensured.

To provide a better understanding of the screen of the present application, it will be further explained and illustrated below. As shown in fig. 1, the screen includes: the base tube 1, the protective housing 2 and the pre-filled particle unit 4 of cover-mounting outside the base tube 1. The base pipe 1 extends in the vertical direction, and the cross section of the base pipe can be a pipe body in various shapes. The base pipe 1 has a plurality of first openings 11 on a sidewall thereof, and the first openings 11 are circumferentially distributed and vertically distributed. The first openings 11 allow fluid to flow from the outside of the base pipe 1 into the interior of the base pipe 1 and also have the effect of partly blocking large particles of impurities in the fluid, such as sand 6.

As shown in fig. 1, the protective casing 2 is sleeved outside the base pipe 1, and the protective casing 2 extends substantially in a vertical direction. The side wall of the protective casing 2 is provided with a plurality of second openings 21, and the second openings 21 are distributed along the circumferential direction and are distributed along the vertical direction. The second openings 21 allow fluid to flow from the outside of the protective casing 2 into the interior of the protective casing 2, while also having the effect of partially blocking large particles of impurities in the fluid, such as sand particles 6. An annular accommodating cavity 3 is formed between the base pipe 1 and the protective shell 2, and the accommodating cavity 3 is filled with pre-filled particle units 4. The upper end of the protective case 2 has an upper sealing portion for sealing the upper end of the accommodation chamber 3. The lower end of the protective case 2 has a lower sealing portion for sealing the lower end of the accommodation chamber 3. In a possible embodiment, the outer sidewall of the protective case 2 may have a concave blocking portion, the upper end and the lower end of which are connected to the sidewall of the protective case 2, and a gap is formed between the left end and the right end of the blocking portion and the sidewall of the protective case 2 to form the second opening 21.

As shown in fig. 1 and 2, the pre-packed particle units 4 are filled in the containing cavities 3, and the particles in the pre-packed particle units 4 are substantially spherical, so that there must be a void between each particle and the adjacent particle. The pores allow for a filtering action of the fluid, e.g. a blocking action of the large grit 6 in the fluid, while ensuring that the fluid can pass through the pre-packed particle units 4 and into the interior of the base pipe 1 of the screen. When the pores among the particles are blocked, the conditions of the pre-filled particle units 4 in the sieve tube are changed to meet the preset conditions, so that the volume of the pre-filled particle units 4 is changed and reduced, the pores among the particles in the pre-filled particle units 4 are increased, sand bridges are damaged, the sieve tube is automatically unblocked after being blocked, the flow capacity of the sieve tube is maintained, and the productivity of an oil well is ensured.

In one possible embodiment, the pre-packed particle unit 4 may include a base particle 41 and a sensing particle 42 whose volume can be changed when a predetermined condition is satisfied. The basic particles 41 serve to form pores between the particles, and when the preset conditions are met, the basic particles 41 are not affected basically, and the pores between the particles still meet the requirements, so that the pre-packed particle unit 4 still has a filtering effect on the fluid. The base particles 41 are made of a material having stable physical properties, and are not easily affected by pressure, acid solution, temperature, alkali solution, and the like. And the volume of the sensitive particles 42 can be changed and reduced when the preset conditions are met, so that particles in the pre-filled particle units 4 are slightly moved, the pores among the particles in the pre-filled particle units 4 are slightly enlarged, the blocked sand bridge is damaged, and the self-blocking removal of the pre-filled sieve tube is realized. In the above process, the degree of increase in the pores between the particles in the pre-packed particle unit 4 when the preset condition is satisfied is controlled by controlling the content of the sensitive particles 42.

In a preferred embodiment, the density of the base particle 41 is 0.95g/cm³To 1.05g/cm³Which is substantially similar to the density of water, so that the base particles 41 are able to float or suspend in a conventional fluid, i.e., a fluid having a density similar to water. Thus, when the screen is run to the bottom of the well, the base particles 41 will be mostly in suspension in the formation fluid, and when the screen is not blocked, the pores between the particles at different positions are basically the same when the base particles 41 are in suspension, so that the particle size of the passing sand can be controlled, and local blockage is not caused. If the density of the base particles 41 is too high or too low, the base particles are all pressed at the upper end or the lower end of the accommodating cavity 3 under the influence of self gravity or buoyancy, and have a larger pressure to be compacted with each other, which is not favorable for the sand-blocking and filtering functions of the fluid of the base particles 41.

In one possible embodiment, the sensitive particles 42 are pressure sensitive particles, and the volume of the pressure sensitive particles can shrink under the condition of the increased external pressure, so that the gaps among the filled ceramic particles among the pre-filled particle units are gradually increased, and self-unblocking is realized. Fig. 3 a-3 c are schematic diagrams of the pre-packed particle unit in the original state, the plugged state and the self-unplugged state in the embodiment of the present invention, as shown in fig. 3a to 3c, when the screen pipe is plugged, for example, in a gravel layer, the pressure difference between the inside and the outside of the screen pipe increases, and under the action of the pressure difference between the inside and the outside, the sensitive particles 42 are shrunk in volume, so that the micro-migration of the particles in the pre-packed particle unit 4 is realized, the pores between the particles in the pre-packed particle unit 4 are increased, the sand bridge is destroyed, the self-unplugging after the screen pipe is plugged is realized, the flow capacity of the screen pipe is maintained, and the oil. When the screen pipe blockage disappears, the pressure difference between the inside and the outside of the screen pipe is reduced and the normal state is recovered, and the volume of the sensitive particles 42 is also recovered. The screen pipe under the structure can be reused theoretically. In the present embodiment, the sensitive particles 42 may be, for example, gas-filled spheres made of plastic or rubber, or solid spheres that can be compressed by themselves.

In another possible embodiment, the sensitive particles 42 are particles that are at least partially soluble under acidic or basic conditions to allow for volume reduction. When the sieve tube is blocked, acid liquid or alkaline liquid is injected into the bottom hole position of the sieve tube, so that the sensitive particles 42 are at least partially dissolved, the volume of the sensitive particles 42 is shrunk or becomes zero, micro-migration of particles in the pre-filled particle units 4 is realized, pores among the particles in the pre-filled particle units 4 are increased, sand bridges are damaged, self-blocking removal after the sieve tube is blocked is realized, the overflowing capacity of the sieve tube is maintained, and the oil well productivity is ensured. The sensitive particles 42 may be made of a substance that does not react with water but dissolves with an acidic liquid or a basic liquid to some extent. For example, the sensitive particles 42 may be preferably alumina particles, rosin-based particles, and the like, which are insoluble in water, odorless, tasteless, extremely hard, and easily hygroscopic without deliquescing (not hygroscopic when burned), and which are amphoteric oxides that are soluble in inorganic acids and alkaline solutions. The rosin particles can be dissolved in ethanol, diethyl ether, acetone, toluene, carbon disulfide, dichloroethane, turpentine, petroleum ether, gasoline, oils and alkali solution, are insoluble in cold water and slightly soluble in hot water, and the rosin has excellent performances of tackifying, emulsifying, softening, damp proofing, corrosion proofing, insulating and the like.

In yet another possible embodiment, the sensitive particles 42 are meltable particles, and the meltable particles can at least partially dissolve or decompose under the condition of increasing temperature so as to reduce the volume, dissolve or decompose part of the meltable particles and flow out of the accommodating cavity along with the formation fluid, so that the gaps among the filled ceramic particles among the pre-filled particle units are gradually increased, and self-unblocking is realized. When the sieve tube is blocked, high-temperature liquid is injected into the bottom hole position of the sieve tube, so that the sensitive particles 42 are at least partially dissolved, the volume of the sensitive particles 42 is shrunk or becomes zero, micro-migration of particles in the pre-filled particle units 4 is realized, pores among the particles in the pre-filled particle units 4 are increased, a sand bridge is damaged, self-unblocking after the sieve tube is blocked is realized, the overflowing capacity of the sieve tube is maintained, and the productivity of an oil well is ensured. For example, polymers such as stearic acid or ice flower wax can be preferably used for the sensitive particles 42. Polymers such as stearic acid or ice flower wax can be dissolved when the temperature reaches over 80 ℃, so that the purpose of reducing the volume of the sensitive particles 42 is achieved. The sensitive particles 42 may also be ceramic particles, polyurethane particles, etc. with a hydrophobically modified epoxy resin coating. The hydrophobically modified epoxy resin coating of the ceramsite can be dissolved at high temperature, thereby achieving the purpose of reducing the volume of the sensitive particles 42. The polyurethane particles have the characteristics of high strength, wear resistance, hydraulic oil resistance and the like, can resist temperature of about 90 ℃, and can slowly start to dissolve when the temperature is exceeded.

In yet another possible embodiment, the sensitive particles 42 are breakable particles that break under downhole or mechanical pressure and flow out of the containment chamber with the formation fluid, causing the voids between the pre-packed particle units to gradually increase, allowing for unplugging. When the sieve tube is blocked, the sieve tube can be pressed underground, so that breakable particles can be broken and flow out of the accommodating cavity along with the formation fluid, the volume of the sensitive particles 42 is shrunk or becomes zero, micro migration of particles in the pre-filled particle units 4 is realized, pores among the particles in the pre-filled particle units 4 are increased, a sand bridge is damaged, automatic blockage removal after the sieve tube is blocked is realized, the overflowing capacity of the sieve tube is maintained, and the oil well productivity is ensured. For example, the breakable particles may start to break when the downhole ambient pressure reaches above 5Mpa, the breaking start pressure may be set according to the reservoir depth, and the breakable particles may be hollow spheres and other substances.

In the various embodiments described above, when the median value of the sand grain diameters in the formation is D, i.e. the diameter of the sand grain 6 that needs to be blocked, the diameter of the particles in the pre-packed particle units 4 is between 6D and 8D. The containing chamber 3 needs to be substantially filled with the pre-filled granular units 4, of course, as far as possible to ensure that the particles in the pre-filled granular units 4 cannot be too tightly packed with each other. In order to ensure the sand control effect, the sizes of the base particles 41 and the sensitive particles 42 in the pre-packed particle units 4 are substantially the same, so that the pores between the particles are substantially the same, and the difference of the sand blocking particle sizes at different positions is avoided. The quantitative proportion range of the base particles 41 and the sensitive particles 42 in the pre-packed particle units 4 is greater than or equal to 9:1, and the number of the sensitive particles 42 cannot be too large, which otherwise would cause the pores between the particles in the pre-packed particle units 4 to be enlarged too much after the plugging is removed, and the performance of the sieve tube is greatly different from the initial performance, so that the performance of the sieve tube after the plugging is not in accordance with the original requirements, especially for the case that the sensitive particles 42 are completely dissolved, the quantitative proportion range of the base particles 41 and the sensitive particles 42 in the pre-packed particle units 4 may be greater than or equal to 94: 6. As a practical matter, the volume of the pre-filled particle unit 4 changes when the preset condition is met, and the total pore space increase range between particles in the pre-filled particle unit 4 is 0-6 percent, so that the aim of blockage removal can be fulfilled.

In one possible embodiment, as shown in FIG. 1, the screen may include: and the elastic mechanism 5 is arranged at the uppermost end and/or the lowermost end of the accommodating cavity 3, and can deform and shrink when the elastic mechanism 5 is pressed, so that the total pore space between the particles in the pre-filled particle unit 4 is enlarged and ranged from 0% to 6%. When the sieve tube is blocked, the internal and external pressure difference of the sieve tube is increased, the pre-filled particle units 4 are increased under the action of the internal and external pressure difference, the pressure applied to the sieve tube is applied to the elastic mechanism 5, the elastic mechanism 5 is slightly deformed and reduced, the pre-filled particle units 4 are driven to slightly move, the pores among the particles in the pre-filled particle units 4 are increased, the sand bridge is damaged, and the self-blocking removal after the sieve tube is blocked is realized. After the blockage is removed, the pressure difference between the inside and the outside of the sieve tube is released, and the elastic mechanism 5 is deformed and recovered. After the screen pipe is plugged again and pressure difference is formed, the elastic mechanism 5 moves slightly again to realize self plugging removal of the pre-filled screen pipe, so that the screen pipe in the embodiment can be used repeatedly without limit. For example, the elastic mechanism 5 may be any substance that is compressed to a reduced volume, such as a rubber-like substance, a spring-like mechanism, or the like.

When the density of the particles in the pre-packed particle units 4 is 0.95g/cm³To 1.05g/cm³In the initial state, the particles exert little force on the elastic means 5. In the clogged state, the particles can uniformly apply the force to the elastic means 5 at the lower and upper ends. If the conventional material with larger density or too light weight is adopted, the pre-filled particle unit 4 can apply too large pressure to the elastic mechanism 5 in the gravity direction or the buoyancy direction due to the self gravity action or the buoyancy action, while the other end cannot be pressed or applied with too small pressure, so that the deformation quantity at the two ends is unbalanced, the pores of the particles of the pre-filled particle unit 4 at different positions are increased unevenly, and the smooth realization of blockage removal is not facilitated.

Also presented herein is a method of unplugging a screen using any of the above, the method comprising: the pre-filled particle units 4 reach the preset conditions, so that the volume of the pre-filled particle units 4 is changed and reduced, the gaps among the particles of the pre-filled particle units 4 are increased, the sand bridge is damaged, and the self-plugging removal of the sieve tube is realized.

There is also provided in the present application a tubular string comprising a screen as in any one of the above.

The screen pipe, the pipe column and the unblocking method solve the problems that the existing pre-filling type screen pipe is easy to block, the productivity of an oil well is greatly reduced after the screen pipe is blocked, the service life of a sand production oil well is shortened, and the like. This application can hold the migration between the 3 middle-sized particles of chamber after the effectual control screen pipe blocks up to can real-time control screen pipe unblock and sand control, provide technical support for solving the jam problem of loose sandstone oil reservoir machinery sand control screen pipe sand control in-process.

All articles and references disclosed, including patent applications and publications, are hereby incorporated by reference for all purposes. The term "consisting essentially of …" describing a combination shall include the identified element, ingredient, component or step as well as other elements, ingredients, components or steps that do not materially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe combinations of elements, components, or steps herein also contemplates embodiments that consist essentially of such elements, components, or steps. By using the term "may" herein, it is intended to indicate that any of the described attributes that "may" include are optional. A plurality of elements, components, parts or steps can be provided by a single integrated element, component, part or step. Alternatively, a single integrated element, component, part or step may be divided into separate plural elements, components, parts or steps. The disclosure of "a" or "an" to describe an element, ingredient, component or step is not intended to foreclose other elements, ingredients, components or steps.

The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (10)

1. A screen, comprising:

the base pipe is provided with a first opening on the side wall;

the protective shell is sleeved outside the base pipe, a second opening is formed in the side wall of the protective shell, and an annular accommodating cavity is formed between the base pipe and the protective shell;

and a pre-filled particle unit filled in the accommodating cavity, wherein the volume of the pre-filled particle unit can be changed to be reduced when a preset condition is met.

2. The screen of claim 1, wherein the pre-packed particle units include base particles and sensitive particles that can change in volume when a predetermined condition is met.

3. The screen according to claim 2, wherein the density of the base particles is 0.95g/cm³To 1.05g/cm³In the meantime.

4. The screen according to claim 2, wherein the pressure sensitive particles are pressure sensitive particles that shrink in volume when subjected to an increase in ambient pressure, resulting in a gradual increase in the voids between the pre-packed particle units, thereby achieving self-plugging.

5. The screen according to claim 2, wherein the sensitive particles are meltable particles, and the meltable particles dissolve or decompose under the action of the temperature rise and flow out of the accommodating cavity along with the formation fluid, so that the gaps among the pre-filled particle units are gradually increased, and self-plugging removal is realized.

6. The screen according to claim 5, wherein the meltable particles begin to dissolve when the ambient temperature reaches 80 degrees and above, and the meltable particles are stearic acid or an ice flower wax polymer.

7. The screen according to claim 2, wherein the sensitive particles are breakable particles that break under downhole and mechanical pressure and flow out of the receiving cavity with the formation fluid, causing the gaps between the pre-packed particle units to gradually increase, thereby effecting unplugging.

8. The screen of claim 7, wherein the breakable particles begin to break when the downhole ambient pressure reaches 5Mpa or more, the break initiation pressure being set according to the reservoir depth, the breakable particles being hollow spherical material.

9. A pipe string comprising a screen as claimed in any one of claims 1 to 8.

10. A method of unplugging using the screen of any of claims 1 to 8, the method comprising:

and (3) enabling the pre-filled particle units to reach a preset condition so that the volume of the pre-filled particle units is changed and reduced, and the inter-particle pores of the pre-filled particle units are increased, so that the sand bridge is damaged, and the self-plugging removal of the sieve tube is realized.

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