Water control screen pipe with backflow prevention function

Abstract

A water control screen pipe with a backflow prevention function comprises a base pipe and a shell, an ICD valve is arranged on the side wall, covered by the shell, of the base pipe and comprises a flow guide channel, a flow control unit is arranged in the flow guide channel, when the well bottom pressure difference is in the forward direction, the flow control unit is located at the first position, and when the well bottom pressure difference is in the reverse direction, the flow control unit is located at the second position. Fluid in the wellbore annulus is not prevented from flowing into the base pipe from the outside of the base pipe through the flow guide channel; and when the well bottom pressure difference is reverse, the flow control unit is located at the second position, the flow guide channel is closed, and the fluid in the base pipe is prevented from flowing into the exterior of the base pipe from the interior of the base pipe through the flow guide channel. When the flow guide channel, provided with the sealing device, on the water control screen pipe needs to be opened, the flow guide channel of the ICD valve can be closed only by filling high-pressure fluid into the base pipe to form reverse shaft bottom pressure difference, the filled fluid can be prevented from leaking into a shaft annulus, high pressure in a central pipe column can be easily established, and the opening pressure of the sealing device can be easily achieved.

Description

TECHNICAL FIELD

[0001] The utility model discloses belong to the petroleum exploitation technical field, and relate to a water control screen device, in particular to a water control screen with anti-backflow function. BACKGROUND

[0002] In the process of oil exploitation, due to the geological structure of different strata in the oil reservoir, the oil reservoir reserves are different, and the oil and gas exploitation sequence and exploitation flow of different strata need to be artificially controlled. The water control screen with pressure control opening function emerges as the times require, and its principle lies in that part or all of the flow channels of the water control screen are closed through sealing devices (such as burst diaphragm), and under the condition of positive well bottom differential pressure (i.e. the pressure in the wellbore annulus is greater than the pressure in the center pipe column), the closed flow channels do not participate in production; when the flow channels need to participate in production, only need to inject high-pressure fluid into the center pipe column to form reverse well bottom differential pressure, and the reverse well bottom differential pressure makes the sealing device fail (such as making the burst diaphragm break), so as to open the flow channels and make them participate in the later production. Further, the sealing device can also be provided with different opening pressure levels (such as burst diaphragms of different thicknesses), so that selective opening can be realized through different levels of pressure. In addition, there is also a water control screen with pressure control closing function, which will not be described here.

[0003] In order to ensure that the flow channels can be reliably opened or closed and avoid misoperation, the opening pressure needs to be set slightly higher than the production pressure. However, when high-pressure fluid is injected into the center pipe column to generate opening or closing pressure, due to the ordinary flow channels with bidirectional conduction or the controllable flow channels that have been opened, under the action of reverse well bottom differential pressure, the injected fluid will leak from the inside of the center pipe column to the wellbore annulus, so that it is difficult to accurately control the reverse well bottom differential pressure in each part of the center pipe column, especially it is difficult to generate high reverse well bottom differential pressure at a deeper position in the wellbore. UTILITY MODEL CONTENTS

[0004] The utility model discloses aim at overcoming the defects of prior art, and provide a water control screen with anti-backflow function, which is beneficial to realize accurate control of the reverse differential pressure in each part of the center pipe column, and generate high reverse well bottom differential pressure at a deeper position in the wellbore.

[0005] In order to achieve the above purpose, the utility model discloses adopt the following technical scheme:

[0006] The water control screen pipe with anti-backflow function comprises a base pipe and a shell, wherein the shell is a cylindrical structure coaxially arranged on the outer side of the base pipe, the two ends of the shell are sealingly connected with the outer side of the base pipe, and a screen is arranged on the middle part of the shell; an ICD valve is arranged on the side wall of the base pipe covered by the shell, the ICD valve comprises a flow guide channel, and the flow guide channel penetrates the inside and outside of the side wall of the base pipe; a flow control unit is arranged in the flow guide channel of the ICD valve, wherein when the bottom hole pressure difference is positive, the flow control unit is located at a first position and does not prevent the fluid in the wellbore annulus from flowing into the inside of the base pipe from the outside of the base pipe through the flow guide channel; when the bottom hole pressure difference is negative, the flow control unit is located at a second position and closes the flow guide channel, thereby preventing the fluid in the base pipe from flowing into the outside of the base pipe from the inside of the base pipe through the flow guide channel.

[0007] Further, the ICD valve comprises a flow guide seat, a valve seat and a valve ring, wherein the valve seat is a circular ring structure arranged in the first through hole of the side wall of the base pipe; the flow guide seat is a circular ring structure, the outer diameter of the flow guide seat is consistent with the inner diameter of the valve seat, and the flow guide seat is fixedly arranged at one end of the inside of the valve seat close to the axis of the base pipe; the valve ring is a circular ring structure, the outer diameter of the valve ring is consistent with the inner diameter of the valve seat, and the valve ring is fixedly arranged at one end of the inside of the valve seat away from the axis of the base pipe; the inner hole of the valve ring forms a moving cavity; the valve seat, the flow guide seat and the valve ring of the ICD valve are coaxially arranged to form the flow guide channel of the ICD valve.

[0008] Further, the flow control unit is a circular ring structure and has a second inner hole in the inside; the flow control unit is arranged in the moving cavity of the valve ring; wherein the outer diameter of the flow control unit is consistent with the diameter of the moving cavity of the valve ring, and the axial length of the flow control unit is smaller than the axial length of the moving cavity of the valve ring; the flow control unit can move axially in the moving cavity of the valve ring under the action of the downhole fluid.

[0009] Further, the valve ring is further provided with a top plate at one end away from the flow guide seat, a flow guide hole is arranged at the position where the top plate axially coincides with the upper end surface of the flow control unit, the outer diameter of the flow guide hole is smaller than the outer diameter of the flow control unit; when the flow control unit is located at the second position, the upper end surface of the flow control unit cooperates with the lower surface of the top plate to close the flow guide hole, thereby closing the flow guide channel.

[0010] Further, the diameter of the first inner hole of the flow guide seat is smaller than the outer diameter of the flow control unit.

[0011] Further, the housing is provided with a second through hole corresponding to the ICD valve axis direction, and a valve cover is detachably arranged in the second through hole.

[0012] Further, the valve seat is provided with an inwardly extending boss at one end close to the base pipe axis, and the flow guide seat is provided with a recess corresponding to the boss at a position corresponding to the boss at one end close to the base pipe axis.

[0013] Further, the valve ring is detachably arranged inside the valve seat from top to bottom, and the bottom surface of the valve ring abuts against the top surface of the flow guide seat.

[0014] Further, the valve seat is provided with an outwardly protruding positioning ring at the outer circumference outside the base pipe.

[0015] Further, a burst diaphragm is arranged between the flow guide seat and the valve ring, and a dissolvable part is arranged in the first inner hole of the flow guide seat.

[0016] Further, the ICD valve comprises a valve seat, a valve ring and a valve cover, wherein the valve seat is a circular ring structure arranged in the first through hole of the base pipe side wall; the valve ring is a circular ring structure, the outer diameter of the valve ring is consistent with the inner diameter of the valve seat, and the valve ring is fixedly arranged inside the valve seat, and the inner hole of the valve ring forms a moving cavity; a cross groove passing through the side wall of the valve ring is arranged at the position of the valve ring protruding out of the side wall of the valve seat; the valve cover is detachably arranged on the housing at a position corresponding to the ICD valve axis direction, the valve cover is a circular structure, and the lower surface abuts against the upper surface of the valve seat; the valve seat, the valve ring and the valve cover of the ICD valve are coaxially arranged, and the valve seat, the moving cavity of the valve ring and the cross groove form a flow guide channel of the ICD valve.

[0017] Further, the flow control unit is a circular ring structure arranged in the moving cavity of the valve ring; wherein the outer diameter of the flow control unit is consistent with the diameter of the moving cavity of the valve ring, and the axial length of the flow control unit is less than the axial length of the moving cavity of the valve ring; under the action of downhole fluid, the flow control unit can move axially in the moving cavity of the valve ring.

[0018] Further, the axial length of the flow control unit is less than the axial length of the moving cavity of the valve ring; when the flow control unit is located at a first position, the flow control unit is lower than the lowest position of the cross groove; when the flow control unit is located at a second position, the flow control unit closes the cross groove.

[0019] Further, the valve ring is further provided with a bottom plate at one end close to the base pipe axis, and a plurality of flow discharge holes with inconsistent directions are arranged on the bottom plate.

[0020] Further, the bottom of the moving cavity is provided with a stepped structure, and the inner diameter of the circular table formed by the stepped structure is smaller than the outer diameter of the flow control unit and larger than the inner diameter of the flow control unit.

[0021] The utility model discloses a kind of water control screen pipes with anti-backflow function, by being provided with flow control unit in the flow guide passage of ICD valve, it can be realized only allow liquid to flow from wellbore annulus into base pipe inside under the condition of positive pressure difference, and not allow liquid to flow from base pipe inside to wellbore annulus under the condition of reverse pressure difference.When facing the need to open the flow guide passage provided with sealing device in the process of well completion or production, only need to fill high-pressure fluid in base pipe to form reverse well bottom pressure difference, at this time, the flow guide passage of ICD valve with flow control unit is closed, it can avoid that filled fluid leaks into wellbore annulus, so it is very beneficial to establish high pressure in central string, and it is easy to reach the opening pressure of sealing device. On the other hand, when the ICD valves of all water control screen pipes 1 are closed, the reverse pressure increase value of different positions in central string also tends to be consistent, and it is more easy to accurately control the reverse well bottom pressure difference of different positions in central string, and it is also more easy to generate expected reverse well bottom pressure difference in deeper position in wellbore. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is the overall structure schematic diagram of a kind of water control screen pipe with anti-backflow function in the utility model patent embodiment;

[0023] Figure 2 It is Figure 1 axial section structure schematic diagram of I part in it;

[0024] Figure 3 It is Figure 2 axial direction opening / closing position schematic diagram of ICD valve in it;

[0025] Figure 4 It is Figure 2 radial direction opening / closing position schematic diagram of ICD valve in it;

[0026] Figure 5 It is Figure 1 axial section structure schematic diagram of another structure of I part in it;

[0027] Figure 6 It is Figure 5 axial direction opening / closing position schematic diagram of ICD valve in it;

[0028] Figure 7 It is Figure 1 axial section structure schematic diagram of another structure of I part in it;

[0029] Figure 8 It is Figure 7Schematic diagram of the open / close position of the ICD valve along the axial direction;

[0030] Figure 9 yes Figure 7 Top view of the middle valve ring.

[0031] Explanation of the reference numerals: water control screen-1, base pipe-11, shell-12, screen-121, ICD valve-2, guide seat-21, first inner hole-211, recess-212, valve seat-22, boss-221, positioning ring-222, valve cover-23, countersunk hole-231, extension surface-232, valve ring-24, guide hole-241, movable cavity-242, top plate-243, cross groove-244, bottom plate-245, drain hole-246, step structure-247, flow control unit-25, second inner hole-251, bursting membrane-3, soluble part-4. DETAILED DESCRIPTION

[0032] The following is combined with Figures 1 to 9 , further illustrate the specific implementation of the utility model patent a water control screen tube with anti-backflow function. The utility model patent a water control screen tube with anti-backflow function is not limited to the description of the following embodiments.

[0033] Example 1:

[0034] This embodiment provides a specific structure of a water control screen tube 1 with a backflow prevention function, such as Figures 1-4 As shown, the water control screen 1 includes a base pipe 11 and an outer shell 12; wherein the outer shell 12 is a cylindrical structure, coaxially arranged on the circumferential outer side of the base pipe 11, with both ends of the outer shell 12 sealed to the circumferential outer side of the base pipe 11, and a screen 121 is provided in the middle; an ICD valve 2 is provided at the side wall of the base pipe 11 covered by the outer shell 12, and the ICD valve 2 includes a diversion channel, which passes through the outside and inside of the side wall of the base pipe 11; it is characterized in that a flow control unit 25 is provided in the diversion channel of the ICD valve 2; wherein, when the bottomhole pressure difference is positive, the flow control unit 25 is in a first position, and does not prevent the fluid in the wellbore annulus from flowing from the outside of the base pipe 11 into the inside of the base pipe 11 through the diversion channel; when the bottomhole pressure difference is negative, the flow control unit 25 is in a second position, closing the diversion channel, thereby preventing the fluid in the base pipe 11 from flowing from the inside of the base pipe 11 into the outside of the base pipe 11 through the diversion channel.

[0035] Specifically, the water control screen pipe 1 has the same overall shape as the central string of the existing well completion construction process, which can be in the form of a short section or a long section, etc. The shell 12 and the screen 121 serve to protect the ICD valve 2 from friction and collision damage when it is lowered into the well, and to prevent particles (including sand production, artificial gravel filling, or sealing particles artificially filled into the annulus of the well based on the "continuous packer water control technology" proposed by the applicant's company, see Chinese patents 201910623000X, 2019104892759, 2021111193667, 202120468829X, 2023113127387, etc. for details) in the wellbore from flowing into the base pipe through the ICD valve 2. The ICD valve 2 is a horizontal well inflow control valve, and one or more ICD valves 2 can be provided on each water control screen pipe 1. The flow channel of the ICD valve 2 is used to guide the production fluid in the wellbore into the base pipe and produce at the wellhead. The flow control unit 25 cooperates with the ICD valve to produce an effect similar to that of a "one-way valve", i.e. only allowing liquid to flow from the wellbore annulus into the base pipe under the condition of a positive bottom hole differential pressure, and not allowing liquid to flow from the base pipe into the wellbore annulus under the condition of a negative bottom hole differential pressure. By providing an ICD valve 2 with a flow control unit 25, when the completion or production process faces the need to open the flow channel provided with a sealing device as described in the background section, only high-pressure fluid needs to be injected into the base pipe to form a negative bottom hole differential pressure. At this time, the flow channel of the ICD valve 2 with the flow control unit 25 is closed, which can prevent the injected fluid from leaking into the wellbore annulus, thereby being very beneficial to establishing a high pressure inside the central string and easily reaching the opening pressure of the sealing device. On the other hand, when all the ICD valves of the water control screen pipes 1 are closed, the increase in negative pressure at different positions in the central string will also tend to be consistent, making it easier to accurately control the negative bottom hole differential pressure at different positions inside the central string, and also making it easier to produce the expected negative bottom hole differential pressure at a deeper position in the wellbore.

[0036] As an optional embodiment, the ICD valve 2 comprises a flow guide base 21, a valve base 22 and a valve ring 24, wherein the valve base 22 is a circular ring structure arranged in the first through hole of the sidewall of the base pipe 11; the flow guide base 21 is a circular ring structure, the outer diameter of the flow guide base 21 is consistent with the inner diameter of the valve base 22, and the flow guide base 21 is fixedly arranged in the inner part of the valve base 22 close to the one end of the axis of the base pipe 11; the valve ring 24 is a circular ring structure, the outer diameter of the valve ring 24 is consistent with the inner diameter of the valve base 22, and the valve ring 24 is fixedly arranged in the inner part of the valve base 22 away from the one end of the axis of the base pipe 11; the inner hole of the valve ring 24 forms a moving cavity 242; the valve base 22, the flow guide base 21 and the valve ring 24 of the ICD valve 2 are coaxially arranged to form the flow guide channel of the ICD valve 2.

[0037] Specifically, the valve base 22 can be welded on the sidewall of the base pipe 11, and is usually fixedly installed, i.e. not disassembled after installation; the valve base 22, the flow guide base 21 and the valve ring 24 of the ICD valve 2 can be connected by threads, for example, the valve base 22 is provided with an inner thread, and the flow guide base 21 and the valve ring 24 are provided with an outer thread, and are connected and fixed with the valve base 22 by threads. Of course, the valve ring 24 as a component that needs to be frequently disassembled can also be connected with the valve base 22 by clamping.

[0038] As an optional embodiment, the flow control unit 25 is a circular ring structure and has a second inner hole 251; the flow control unit 25 is arranged in the moving cavity 242 of the valve ring 24; wherein the outer diameter of the flow control unit 25 is consistent with the diameter of the moving cavity 242 of the valve ring 24, and the axial length of the flow control unit 25 is less than the axial length of the moving cavity 242 of the valve ring 24; under the action of the downhole fluid, the flow control unit 25 can move axially in the moving cavity 242 of the valve ring 24.

[0039] Specifically, as shown in the left drawing of FIG. 2, when the normal liquid production, the positive bottom hole differential pressure, the flow control unit 25 is located at the first position, and under the action of the positive bottom hole differential pressure P, the liquid production Q flows out from below; when the user fills the central pipe string with high-pressure fluid, as shown in the right drawing of FIG. 2, under the action of the reverse bottom hole differential pressure P, the fluid in the flow guide channel changes direction and drives the flow control unit 25 to move from the first position to the second position. Figure 3 Figure 4 Figure 3 Figure 4

[0040] ​​​​As an optional embodiment, the valve ring 24 is further provided with a top plate 243 at one end away from the flow guide base 21, and the top plate 243 is provided with a flow guide hole 241 at a position axially coinciding with the upper end surface of the flow control unit 25, and the outer diameter of the flow guide hole 241 is smaller than the outer diameter of the flow control unit 25; when the flow control unit 25 is located at the second position, the upper end surface of the flow control unit 25 cooperates with the lower surface of the top plate 243 to close the flow guide hole 241, thereby closing the flow guide passage.

[0041] Specifically, the top plate 243 can be integrally formed with the annular portion of the valve ring 24. The flow guide hole 241 can be provided with one or more, and preferably can be equidistantly distributed in the circumferential direction. The outer diameter of the flow guide hole 241 is smaller than the outer diameter (i.e. the annular thickness) of the flow control unit 25, so as to ensure that when the flow control unit 25 is moved from the first position to the second position, the upper annular end surface of the flow control unit 25 can completely cover the flow guide hole 241, thereby closing the flow guide hole 241, and then achieving the effect of closing the flow guide passage.

[0042] As an optional embodiment, the diameter of the first inner hole 211 of the flow guide base 21 is smaller than the outer diameter of the flow control unit 25.

[0043] Specifically, the diameter of the first inner hole 211 of the flow guide base 21 is designed to be smaller than the outer diameter of the flow control unit 25, which aims to support the flow control unit 25 from below to avoid the flow control unit 25 from falling into the base pipe. At the same time, the diameter of the first inner hole 211 of the flow guide base 21 should also be not less than the inner diameter of the flow control unit 25, which aims to ensure a large enough flow area to ensure the liquid production rate; and when a reverse bottom hole pressure difference occurs, the reverse bottom hole pressure difference can act on the lower surface of the flow control unit 25, thereby pushing the flow control unit 25 to move upward.

[0044] As an optional embodiment, the housing 12 is further provided with a second through hole at a position corresponding to the axis direction of the ICD valve 2, and the second through hole is detachably provided with a valve cover 23; the valve cover 23 is a circular plate structure, and the diameter of the valve cover 23 is greater than the outer diameter of the valve ring 24.

[0045] Specifically, the valve cover 23 is designed to provide a space for replacing the flow guide base 21, the valve ring 24 and the flow control unit 25. Specifically, in the first aspect, in order to achieve the predetermined flow control effect, it is necessary to set the flow guide base 21 with different flow areas at different positions, which requires frequent replacement of the flow guide base 21 with different types; in the second aspect, when the valve ring 24 and the flow control unit 25 are worn or damaged, they also need to be replaced; in the third aspect, referring to the burst diaphragm 3 disclosed in Embodiment 2, the burst diaphragm 3 also needs to be replaced when it bursts next time. The above requirements require that a space for maintenance operation must be provided for these components. Preferably, the valve cover 23 is connected and fixed to the shell 12 by screwing, and the valve cover 23 is also provided with two or more counterbores 231 to facilitate the insertion of a dismounting tool to rotate the valve cover 23. The diameter of the valve cover 23 should be greater than the outer diameter of the flow guide base 21, the valve ring 24 and the flow control unit 25, so that the flow guide base 21, the valve ring 24 and the flow control unit 25 can be taken out of or placed into the second through hole where the valve cover 23 is located.

[0046] As an optional embodiment, the valve seat 22 is provided with an inwardly extending boss 221 at one end close to the axis of the base pipe 11, and the flow guide base 21 is provided with a recess 212 corresponding to the boss 221 at a position corresponding to the boss 221 at one end close to the axis of the base pipe 11.

[0047] Specifically, when the flow guide base 21 is installed, the recess 212 of the flow guide base 21 is pressed against the boss 221 of the valve seat 22, so that reliable positioning between the two can be achieved.

[0048] As an optional embodiment, the valve ring 24 is detachably installed inside the valve seat 22 from top to bottom, and the bottom surface of the valve ring 24 abuts against the top surface of the flow guide base 21.

[0049] Specifically, after the bottom surface of the valve ring 24 abuts against the top surface of the flow guide base 21, the two can form a positioning structure to ensure stable and reliable installation.

[0050] As an optional embodiment, the valve seat 22 is provided with an outwardly protruding positioning ring 222 at the outer circumference outside the base pipe 11.

[0051] Specifically, the valve seat 22 can be fixedly connected to the base pipe 11 by welding or screwing. By providing the positioning ring 222, the valve seat 22 can be positioned on the base pipe 11 with appropriate depth and without inclination, thereby improving the convenience and reliability of assembly of components.

[0052] Embodiment 2:

[0053] This embodiment provides a water control screen with anti-backflow function. Figures 5-6 As shown, this embodiment adds a bursting diaphragm 3 and a soluble component 4 to the water control screen disclosed in Example 1. A bursting diaphragm 3 is sandwiched between the guide seat 21 and the valve ring 24, and a soluble component 4 is provided in the first inner hole 211 of the guide seat 21.

[0054] Specifically, the bursting diaphragm 3 is squeezed and installed between the guide seat 21 and the valve ring 24. By providing the bursting diaphragm 3, the water control screen tube with anti-backflow function provided in this embodiment has a pressure opening function, and also has the one-way anti-backflow function described in Example 1. Preferably, the bursting diaphragms 3 installed on the ICD valves at different positions can be of different models, so that the ICD valves at different positions can be opened in batches in a controllable manner. When the bursting diaphragm 3 bursts, the ICD valve can participate in liquid production. The soluble part 4 can be completely dissolved within a certain period of time (for example, 5 to 7 days) under certain acid and alkali (pH), temperature (T), and pressure (P) conditions. The purpose of providing the soluble part 4 is to protect the bursting diaphragm 3 from accidental explosion. Specifically, when the "continuous sealing body filling and water control" technical solution is adopted, it is necessary to fill the sealing particles in the wellbore annulus with a fluid with high pressure. The provision of a soluble part 4 can prevent the high-pressure fluid from accidentally bursting the bursting membrane 3, thereby causing the ICD valve to fail and then be unable to perform controllable opening control.

[0055] The working process of the ICD valve of the water control screen tube with anti-backflow function provided in this embodiment is as follows: Figure 5 As shown, see Figure 9 As shown in the upper left figure, in the initial state, the soluble part 4 can protect the bursting diaphragm 3 and gradually dissolves under the action of the fluid Q; referring to the upper right figure, the reverse bottomhole pressure differential P in the base pipe 12 acts on the bursting diaphragm 3 but does not destroy the bursting diaphragm 3; referring to the lower left figure, the reverse bottomhole pressure differential P in the base pipe 12 acts on the bursting diaphragm 3 and has destroyed the bursting diaphragm 3. At this time, the flow control unit 25 moves upward under the action of pressure or fluid, closing the diversion hole 241; referring to the lower right figure, under the positive bottomhole pressure differential P in the wellbore annulus, the produced fluid forms a flow rate Q through the diversion channel of the ICD valve and flows into the interior of the base pipe 12.

[0056] Example 3:

[0057] This embodiment provides another water control screen tube with anti-backflow function, such as Figures 7-9The water control screen with anti-backflow function provided in Example 1 is different only in the structure of the ICD valve 2. Specifically, the water control screen with anti-backflow function in this embodiment includes a valve seat 22, a valve ring 24 and a valve cover 23. The valve seat 22 is a circular ring structure and is arranged in the first through hole of the sidewall of the base pipe 11. The valve ring 24 is also a circular ring structure, the outer diameter of the valve ring 24 is consistent with the inner diameter of the valve seat 22, and the valve ring 24 is fixedly arranged inside the valve seat 22. The inner hole of the valve ring 24 forms a moving cavity 242. A cross groove 244 is arranged through the sidewall of the valve ring 24 at the position where the upper part of the valve ring 24 protrudes from the sidewall of the valve seat 22. The valve cover 23 is detachably arranged on the outer shell 12 at a position corresponding to the axis direction of the ICD valve 2. The valve cover 23 is a circular structure, and the lower surface thereof abuts against the upper surface of the valve seat 22. The valve seat 22, the valve ring 24 and the valve cover 23 of the ICD valve 2 are coaxially arranged, and the valve seat 22, the moving cavity 242 of the valve ring 24 and the cross groove 244 form the flow guide channel of the ICD valve 2.

[0058] Specifically, the valve seat 22 has the same structure as that in Example 1, and the inner side bottom of the valve seat 22 is also provided with an inwardly protruding boss for positioning the valve ring 24 installed inside. After the valve ring 24 is installed into the valve seat 22, the lower bottom surface of the valve ring 24 abuts against the boss, thereby improving the reliability of installation and the accuracy of positioning. The valve ring 24 can be detachably connected with the valve seat 22 in a threaded or clamped manner. The cross groove 244 is a structure of four through holes arranged on the sidewall of the valve ring 24. Of course, other numbers of through hole structures, such as one, three or six, can also be adopted, as long as the required flow area is met, which all belong to equivalent technical solutions. The structure of the valve cover 23 is similar to that disclosed in Example 1. Preferably, a protruding extension surface 232 is arranged at the central position of the lower surface of the valve cover 23. The purpose of arranging the extension surface 232 is to avoid the upper surface of the flow control unit 25 from being adsorbed to the lower surface of the valve cover 23 and unable to move downward when the bottom hole differential pressure changes from reverse to positive.

[0059] As an optional embodiment, the flow control unit 25 is a circular ring structure and is arranged in the moving cavity 242 of the valve ring 24. The outer diameter of the flow control unit 25 is consistent with the diameter of the moving cavity 242 of the valve ring 24, and the axial length of the flow control unit 25 is smaller than the axial length of the moving cavity 242 of the valve ring 24. Under the action of the downhole fluid, the flow control unit 25 can move axially in the moving cavity 242 of the valve ring 24.

[0060] Specifically, when the bottom hole differential pressure is positive, as shown in FIG. 2, the flow control unit 25 is in the positive position, and the flow control unit 25 is in the positive position. Figure 8As shown in the left figure, the fluid in the wellbore annulus flows into the base pipe 12 under the action of the bottom hole pressure difference P, thereby pushing the flow control unit 25 to the first position; when the bottom hole pressure difference changes from positive to reverse, as shown in FIG. Figure 8 As shown in the right figure, the fluid in the base pipe 12 pushes the flow control unit 25 upward to the second position under the action of the reverse bottom hole pressure difference P.

[0061] As an optional embodiment, the axial length of the flow control unit 25 is smaller than the axial length of the moving cavity 242 of the valve ring 24; wherein, when the flow control unit 25 is located at the first position, the flow control unit 25 is lower than the lowest position of the cross groove 244; when the flow control unit 25 is located at the second position, the flow control unit 25 closes the cross groove 244.

[0062] Specifically, such as Figure 8 As shown in the left figure, when the bottom hole pressure difference is positive, the flow control unit 25 is in the first position. At this time, the upper surface of the flow control unit 25 is lower than the lowest position of the cross groove 244, and does not hinder the flow of fluid through the cross groove 244. The fluid in the wellbore annulus passes through the cross groove 244, the second inner hole 251 of the flow control unit 25, and the leakage hole 246 of the valve ring 24 in sequence, and flows into the interior of the base pipe 12. Figure 8 As shown in the right figure, when the bottom hole pressure difference changes from positive to reverse, the flow control unit 25 moves upward from the first position to the second position, and the side and / or top of the flow control unit 25 close the cross groove 244 and / or the second inner hole 251, thereby closing the fluid channel of the ICD valve.

[0063] As an optional embodiment, a bottom plate 245 is further provided at one end of the valve ring 24 close to the axis of the base pipe 11 , and a plurality of leakage holes 246 with inconsistent directions are provided on the bottom plate 245 .

[0064] Specifically, the purpose of providing the bottom plate and the drain hole 246 is to change the direction of the fluid entering the base pipe, so as to prevent the fluid from directly impacting the inner wall of the opposite base pipe along the axis of the ICD valve, thereby damaging the base pipe. Figure 8 and Figure 9 As shown, there are six leakage holes 246, evenly and symmetrically distributed around the circumference. The central leakage hole 246 is oriented along the axis of the ICD valve, while the five leakage holes 246 around the circumference are oriented at a certain angle to the axis of the ICD valve, thereby preventing the leaked fluid from directly impacting the inner wall of the opposite base pipe.

[0065] As an optional embodiment, a step structure 247 is provided at the bottom of the movable cavity 242 . The inner diameter of the truncated cone formed by the step structure 247 is smaller than the outer diameter of the flow control unit 25 and larger than the inner diameter of the flow control unit 25 .

[0066] Specifically, the purpose of setting the step structure 247 is to support the flow control unit 25 from below, avoiding the flow control unit 25 from falling into the base pipe. At the same time, the lower surface of the flow control unit 25 is avoided from directly adhering to the bottom plate 245, thereby causing the leakage hole 246 to be closed.

[0067] The above is a further detailed description of the utility model patent in combination with specific preferred embodiments, and cannot be determined that the specific implementation of the utility model patent is limited to these descriptions. For ordinary skilled persons in the technical field of the utility model patent, without departing from the concept of the utility model patent, a number of simple deductions or substitutions can be made, which should be regarded as belonging to the protection scope of the utility model patent.

Claims

1. A water control screen pipe with anti-backflow function, comprising a base pipe and an outer shell; wherein, The shell is a cylindrical structure, coaxially arranged on the outer side of the base pipe, both ends of the shell are sealingly connected with the outer side of the base pipe, and the middle part is provided with a screen. When the bottom hole pressure difference is positive, the flow control unit is located at the first position and does not prevent the fluid in the wellbore annulus from flowing into the base pipe from the outside of the base pipe through the flow channel. When the bottom hole pressure difference is reversed, the flow control unit is located at the second position, and the flow channel is closed, thereby preventing the fluid in the base pipe from flowing into the base pipe from the inside of the base pipe through the flow channel.

2. The water control screen pipe with anti-backflow function according to claim 1, characterized in that: The ICD valve includes a flow guide seat, a valve seat and a valve ring. The valve seat is a circular ring structure arranged in the first through hole of the side wall of the base pipe. The flow guide seat is a circular ring structure, the outer diameter of the flow guide seat is consistent with the inner diameter of the valve seat, and the flow guide seat is fixedly arranged in the inside of the valve seat close to one end of the base pipe axis. The valve ring is a circular ring structure, the outer diameter of the valve ring is consistent with the inner diameter of the valve seat, and the valve ring is fixedly arranged in the inside of the valve seat away from one end of the base pipe axis; the inner hole of the valve ring forms a moving cavity. The valve seat, the flow guide seat and the valve ring of the ICD valve are coaxially arranged to form the flow channel of the ICD valve.

3. The water control screen pipe with anti-backflow function according to claim 2, characterized in that: The flow control unit is a circular ring structure with a second inner hole in the inside; the flow control unit is arranged in the moving cavity of the valve ring; wherein the outer diameter of the flow control unit is consistent with the diameter of the moving cavity of the valve ring, and the axial length of the flow control unit is less than the axial length of the moving cavity of the valve ring; the flow control unit can move axially in the moving cavity of the valve ring under the action of downhole fluid.

4. The water control screen pipe with anti-flowback function according to claim 3, characterized in that: The end of the valve ring away from the flow guide seat is also provided with a top plate, the flow guide hole is provided at the position where the top plate axially coincides with the upper end surface of the flow control unit, the outer diameter of the flow guide hole is smaller than the outer diameter of the flow control unit; when the flow control unit is located at the second position, the upper end surface of the flow control unit cooperates with the lower surface of the top plate to close the flow guide hole, thereby closing the flow channel.

5. The water control screen pipe with anti-flowback function according to claim 4, characterized in that: The diameter of the first inner hole of the flow guide seat is smaller than the outer diameter of the flow control unit.

6. The water control screen pipe with anti-flow-back function according to claim 5, characterized in that: The position corresponding to the axis direction of the ICD valve on the shell is also provided with a second through hole, and a valve cover is detachably arranged in the second through hole; the valve cover is a circular plate structure, and the diameter of the valve cover is greater than the outer diameter of the valve ring.

7. The water control screen pipe with anti-backflow function according to claim 2, characterized in that: The end of the valve seat close to the base pipe axis is provided with an inwardly extending boss, and the end of the flow guide seat close to the base pipe axis is provided with a recess corresponding to the boss.

8. The water control screen pipe with anti-flowback function according to claim 7, characterized in that: The valve ring is detachably installed in the inside of the valve seat from top to bottom, and the bottom surface of the valve ring abuts against the top surface of the flow guide seat.

9. The water control screen pipe with anti-flow-back function according to claim 2, characterized in that: The valve seat located at the outer circumference of the base pipe outside is provided with an outwardly protruding positioning ring.

10. The water control screen pipe with anti-flow-back function according to claim 2, characterized in that: The flow guide seat and the valve ring are also clamped with a burst diaphragm, and the first inner hole of the flow guide seat is provided with a dissolvable part.

11. The water control screen pipe with anti-flow-back function according to claim 1, characterized in that: The ICD valve comprises a valve seat, a valve ring and a valve cover, wherein, The valve seat is a circular ring structure and is arranged in the first through hole of the sidewall of the base pipe; The valve ring is a circular ring structure, the outer diameter of the valve ring is consistent with the inner diameter of the valve seat, and the valve ring is fixedly arranged in the interior of the valve seat, and the inner hole of the valve ring forms a moving cavity; a cross groove passing through the sidewall of the valve ring is arranged on the upper part of the valve ring which protrudes from the sidewall of the valve seat; The valve cover is detachably arranged on the outer shell at a position corresponding to the axis direction of the ICD valve, and the valve cover is a circular structure with a lower surface abutting against the upper surface of the valve seat; The valve seat, the valve ring and the valve cover of the ICD valve are coaxially arranged, and the valve seat, the moving cavity of the valve ring and the cross groove form the flow guide channel of the ICD valve.

12. The water control screen pipe with anti-flow-back function according to claim 11, characterized in that: The flow control unit is a circular ring structure and is arranged in the moving cavity of the valve ring; wherein the outer diameter of the flow control unit is consistent with the diameter of the moving cavity of the valve ring, and the axial length of the flow control unit is smaller than the axial length of the moving cavity of the valve ring; under the action of the downhole fluid, the flow control unit can move axially in the moving cavity of the valve ring.

13. The water control screen pipe with anti-flow-back function according to claim 12, characterized in that: The axial length of the flow control unit is smaller than the axial length of the moving cavity of the valve ring; wherein, When the flow control unit is located at the first position, the flow control unit is lower than the lowest position of the cross groove; When the flow control unit is located at the second position, the flow control unit closes the cross groove.

14. The water control screen pipe with anti-flow-back function according to claim 13, characterized in that: The valve ring is further provided with a bottom plate at one end close to the axis of the base pipe, and a plurality of drainage holes with inconsistent directions are arranged on the bottom plate.

15. The water control screen pipe with anti-flow-back function according to claim 14, characterized in that: The bottom of the moving cavity is provided with a step structure, and the inner diameter of the circular platform formed by the step structure is smaller than the outer diameter of the flow control unit and greater than the inner diameter of the flow control unit.

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