AICD valve with backflow prevention function and water control screen pipe
By setting a flow control unit at the outlet of the AICD valve, the problem of fluid leakage under reverse bottom hole pressure differential in the existing technology is solved, and precise differential pressure control of the central tubing string and the generation of high bottom hole pressure differential are achieved, reducing operational risks and costs.
Patent Information
- Application Number
- CN202423174723.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2034-12-23
AI Technical Summary
Existing AICD valves have difficulty achieving precise control of all parts of the central tubing under reverse bottom pressure differential conditions, especially in deeper parts of the wellbore where it is difficult to generate a high reverse bottom pressure differential, leading to fluid leakage and increasing operation time and economic costs.
A flow control unit is installed at the outlet of the AICD valve. The flow control unit opens under forward bottom hole pressure differential and closes under reverse bottom hole pressure differential to prevent fluid backflow and achieve unidirectional flow.
It achieves precise control of reverse pressure differential at various points in the central tubing string, avoids fluid leakage, reduces operational risks and costs, and ensures the generation of high reverse bottomhole pressure differential at deeper locations in the wellbore.
Smart Images
Figure CN223524518U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model discloses belong to the petroleum exploitation technical field, and relate to a kind of AICD valve and water control screen pipe, especially a kind of AICD valve with anti-backflow function. BACKGROUND
[0002] Firstly, AICD valve (intelligent fluid flow control valve) is commonly used device in oil and gas exploitation field, to the most commonly used Halliburton AICD valve, as shown in Figure 1 And Figure 2 As shown, Halliburton AICD valve utilizes the flow passage of system design to control fluid flow, including three independent dynamic fluid components: a viscosity selector, a flow switch and a flow restrictor, three play a role together, make fluid flow limited or unrestricted. Wherein viscosity selector is mainly based on the fluid viscosity, density and speed parameters in flow passage system, by "identification" to the fluid flowing through AICD valve, then fluid is divided into two. When fluid leaves viscosity selector, enters flow switch (flow bifurcation), it will guide most of selected low flowability fluid (such as crude oil) to one branch of flow passage bifurcation according to fluid property. Finally, flow restrictor limits high flowability fluid (such as gas or bottom water) to enter production string, while there is almost no restriction to selected low flowability fluid through.
[0003] Secondly, in the prior art, for the wellbore with high water yield, usually adopt the completion structure with water control function, for example, adopt the completion structure of "continuous packer water control technology" (see Chinese patent 201910623000X a packer method and completion structure for simultaneous injection and production, 2019104892759 artificial well wall forming method and completion structure for preventing mud production or channeling of mudstone layer, 2021111193667 continuous packer for improving axial anti-channeling flow capacity in downhole annulus, 202120468829X water injection well, 2023113127387 a method for reducing water and increasing oil in fractured oil and gas reservoir oil and gas well packing packer particles, etc. Literature) usually install AICD valve with water control screen pipe together to realize the water control function of downhole production, to seek to reduce the water content of produced liquid.
[0004] In a third aspect, in the process of oil exploitation, due to different geological structures of different strata in the oil reservoir and different oil reservoir reserves, the order and flow rate of oil and gas exploitation of different strata need to be artificially controlled. A water control screen pipe with pressure control opening function emerges as the times require. The principle is that part or all of the flow channels of the water control screen pipe are closed by a sealing device (such as a burst diaphragm). Under the condition of a positive bottom hole differential pressure (i.e. the pressure in the wellbore annulus is greater than the pressure in the center string), the closed flow channels do not participate in production. When the flow channels need to participate in production, only a high-pressure fluid needs to be injected into the center string to form a reverse bottom hole differential pressure, which causes the sealing device to fail (such as causing the burst diaphragm to break), thereby opening the flow channels and allowing them to participate in 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 achieved by different pressure levels. In addition, there is also a water control screen pipe with pressure control closing function, which will not be described here.
[0005] To ensure reliable opening or closing of the flow channels and avoid misoperation, the opening pressure needs to be set slightly higher than the production pressure. However, when injecting a high-pressure fluid into the center string to generate an opening or closing pressure, the AICD valve in the water control screen pipe described above has a bidirectional conduction function. Under the action of a reverse bottom hole differential pressure, the injected fluid will leak from the inside of the center string to the wellbore annulus through the AICD valve, making it difficult to accurately control the reverse bottom hole differential pressure at different positions in the center string, especially at deeper positions in the wellbore. In the prior art, the pressurization operation in the center string can be completed by running a seat service tool into the center string, but this not only increases the operation time and economic cost, but also increases the additional operation risk, such as the seat service tool being stuck in the center string and unable to be pulled out, the center string being damaged by impact, etc. Practical new type content
[0006] The purpose of the utility model patent is to overcome the defects of the prior art and provide an AICD valve and a water control screen pipe with an anti-backflow function, which is beneficial to accurately control the reverse differential pressure at different positions in the center string and generate a higher reverse bottom hole differential pressure at deeper positions in the wellbore.
[0007] To achieve the above purpose, the patent adopts the following technical solutions:
[0008] The application discloses an AICD valve with an anti-backflow function.
[0009] Further, the control flow unit is in a cylindrical structure and is coaxially arranged in the liquid outlet hole; when the control flow unit is located at the first position, the upper end surface of the control flow unit is separated from the upper plate of the AICD valve, and the fluid in the flow guide channel can flow out through the inner hole of the control flow unit; when the control flow unit is located at the second position, the upper end surface of the control flow unit abuts against the upper plate of the AICD valve, the inner hole of the control flow unit is closed, and the fluid is prevented from flowing through the inner hole of the control flow unit.
[0010] Further, the AICD valve with the anti-backflow function further comprises a detachable valve seat which is in an annular structure and is arranged in the annular space between the inner wall of the flow guide channel and the outer wall of the control flow unit, and is used for limiting the control flow unit to move only in the axial direction; the bottom of the valve seat is further provided with a first annular positioning table, and the inner diameter of the first positioning table is greater than the inner diameter of the control flow unit and is smaller than the outer diameter of the control flow unit.
[0011] Further, the bottom of the valve seat is further provided with a second annular positioning table, and the outer diameter of the second positioning table is greater than the diameter in the flow guide channel.
[0012] Further, the control flow unit is in a cylindrical structure and is coaxially arranged in the liquid outlet hole, the outer diameter of the control flow unit is consistent with the diameter of the liquid outlet hole; the upper cover is further provided with a valve cover, and the lower surface of the valve cover is in a plane structure; when the control flow unit is located at the first position, the upper end surface of the control flow unit is separated from the lower surface of the valve cover, and the fluid in the flow guide channel can flow out through the inner hole of the control flow unit; when the control flow unit is located at the second position, the control flow unit abuts against the lower surface of the valve cover, the inner hole of the control flow unit is closed, and the fluid is prevented from flowing through the inner hole of the control flow unit.
[0013] Further, the bottom of the liquid outlet hole is further provided with a third annular positioning table, and the inner diameter of the third annular positioning table is greater than the inner diameter of the control flow unit and is smaller than the outer diameter of the control flow unit.
[0014] Further, the valve cover is detachably arranged on the upper plate, and the diameter of the main body part of the valve cover is greater than the outer diameter of the control flow unit.
[0015] Furthermore, the upper part of the valve cover is provided with a fourth annular positioning platform, the outer diameter of which is larger than the diameter of the main body of the valve cover.
[0016] Furthermore, a hexagonal countersunk hole is provided in the center of the upper part of the valve cover.
[0017] To achieve the above objectives, this patent adopts the following technical solution:
[0018] A water control screen pipe with anti-backflow function, wherein the water control screen pipe is provided with an AICD valve with anti-backflow function as described above.
[0019] This patent discloses an AICD valve and water control screen with anti-backflow function. By incorporating a flow control unit within the AICD valve, it ensures that liquid flows from the wellbore annulus into the water control screen only under positive pressure differential conditions, while preventing liquid from flowing out of the water control screen into the wellbore annulus under reverse pressure differential conditions. When it is necessary to open a flow channel equipped with a sealing device during well completion or production, high-pressure fluid is simply injected into the central tubing to create a reverse bottomhole pressure differential. At this time, the AICD valve with the flow control unit closes, preventing the injected fluid from leaking into the wellbore annulus. This is highly beneficial for establishing high pressure in the central tubing and easily reaching the opening pressure of the sealing device. On the other hand, when all AICD valves on the water control screens are closed, the increase in reverse pressure at different locations in the central tubing tends to be consistent, making it easier to accurately control the reverse bottomhole pressure differential at different locations within the central tubing and to generate the expected reverse bottomhole pressure differential at deeper locations in the wellbore. Attached Figure Description
[0020] Figure 1 This is a three-dimensional structural diagram of an AICD valve;
[0021] Figure 2 yes Figure 1 A three-dimensional perspective view of the internal flow channel of the AICD valve;
[0022] Figure 3 This is a cross-sectional view of an AICD valve with anti-backflow function in Embodiment 1;
[0023] Figure 4 yes Figure 3 A schematic diagram of the structure when the liquid outlet hole is open;
[0024] Figure 5 yes Figure 3 A schematic diagram of the structure when the liquid outlet hole is closed;
[0025] Figure 6 This is a cross-sectional view of an AICD valve with anti-backflow function in Example 2;
[0026] Figure 7 is Figure 6 structure diagram when the liquid outlet hole is open;
[0027] Figure 8 is Figure 6 structure diagram when the liquid outlet hole is closed;
[0028] Figure 9 is a schematic diagram of the overall structure of a water control screen with anti-backflow function in Example 3; reference signs: AICD valve 1, valve body 11, flow guide channel 111, liquid outlet hole 112, upper plate 113, lower plate 114, third annular positioning platform 115, flow control unit 12, inner hole 121, valve seat 13, first annular positioning platform 131, second annular positioning platform 132, valve cover 14, fourth annular positioning platform 141, hexagonal counterbore 142, water control screen body 2. DETAILED DESCRIPTION
[0029] The following will be described in detail in combination with the accompanying Figures 1 to 9 , further illustrating the specific embodiments of the AICD valve with anti-backflow function of the present patent. The AICD valve with anti-backflow function of the present patent is not limited to the description of the following examples.
[0030] First, the basic structure of the AICD valve in the prior art will be introduced. As shown in Figure 1 and Figure 2 , it is the specific structure of the AICD valve of Halliburton in the prior art. The valve body 11 of the AICD valve 1 is a flat cuboid structure as a whole, and the upper and lower sides are square plate structures of the upper plate and the lower plate (the upper plate is not shown in Figure 2 ). The annular flow guide channel 111 is clamped between the upper plate and the lower plate, and the flow guide channel 111 can be provided as two, one end of each flow guide channel 111 communicates with the outside of the side wall of the valve body 11, and the other end communicates with the circular hollow structure in the middle of the valve body 11. The circular hollow structure is provided with a liquid outlet hole 112 corresponding to the position of the lower plate in the middle. The AICD valve is installed on the side wall of the water control screen, and its basic principle works as follows: the downhole produced liquid enters the inside circular hollow structure of the valve body 11 from the outside through the flow guide channel 111 (the fluid direction is shown by the arrows on the left and right sides in Figure 2 ), and the flow guide channel 111 is designed to have a special structure, which can make more oil in the produced liquid more easily enter the middle of the hollow structure and flow into the inside of the screen pipe (i.e. the inside of the central pipe column, the fluid direction is shown by the arrow in Figure 2(The downward arrow in the middle) then produces water from the wellhead; while more water in the produced fluid, due to its high fluidity, continues to flow in a ring within the hollow structure. Under the action of centrifugal force, it is not as easy for the oil to flow to the position of the outlet hole 112, thus achieving the effect of "controlling water and increasing oil" by "trapping" more water in the hollow structure.
[0031] like Figure 2 As indicated by the upward arrow in the middle, since the outlet hole 112 of the AICD valve is in a bidirectional open state, when the pressure of the fluid in the screen pipe is greater than the annular pressure in the wellbore, the fluid in the screen pipe flows out of the screen pipe through the outlet hole 112 and enters the annular space in the wellbore. Therefore, the technical problems described in the background section, such as "it is difficult to achieve precise control of the reverse bottom hole pressure differential at various points in the central tubing string" and "it is difficult to generate a high reverse bottom hole pressure differential at a deeper position in the wellbore", arise.
[0032] The inventive concept of this patent lies in setting a flow control unit 12 at the outlet hole 112 of the AICD valve. The flow control unit 12 functions as a "one-way valve". When there is a positive pressure differential at the bottom of the well, the one-way valve opens without affecting normal production. When it is necessary to establish a reverse pressure differential, fluid is injected into the central tubing through the wellhead. The one-way valve can automatically close under the action of the reverse pressure differential, thereby achieving the function of "anti-backflow". This can prevent pressure leakage inside the central tubing and thus solve the above-mentioned technical problem that this patent aims to solve.
[0033] Example 1:
[0034] This embodiment provides an AICD valve with anti-backflow function, such as... Figures 3 to 5 As shown, the AICD valve provided in this embodiment moves along... Figure 1 A cross-sectional view of the valve 1 with anti-backflow function, cut along the AA direction, shows that the valve 1 includes a valve body 11. The valve body 11 has a flow guide channel 111 and a liquid outlet 112 inside. One end of the flow guide channel 111 is connected to the side wall of the valve body, and the other end is connected to the liquid outlet 112. The liquid outlet 112 also has a flow control unit 12. When the bottom hole pressure difference is positive, the flow control unit 12 is in a first position, not preventing the fluid in the flow guide channel 111 from flowing out through the liquid outlet 112. When the bottom hole pressure difference is negative, the flow control unit 12 is in a second position, closing the liquid outlet 112, thereby preventing the fluid in the flow guide channel 111 from flowing out through the liquid outlet 112.
[0035] Specifically, the overall structure of the AICD valve 1 with the anti-flowback function is consistent with that of the Halliburton AICD valve in the prior art, and the difference lies in that the flow control unit 12 is arranged in the liquid outlet hole 112, the flow control unit 12 is coaxially arranged in the liquid outlet hole 112 and can move up and down along the axial direction under the action of the bottom hole differential pressure and the fluid flowing through the inside of the AICD valve 1. When the direction of the bottom hole differential pressure is unchanged, the flow control unit 12 is stationary at the first position or the second position according to the direction of the bottom hole differential pressure; when the direction of the bottom hole differential pressure changes, the flow control unit 12 changes position under the action of the pressure and the fluid, thereby changing the working state of the AICD valve 1.
[0036] As an optional implementation, the flow control unit 12 is a cylindrical structure and is coaxially arranged in the liquid outlet hole 112; when the flow control unit 12 is located at the first position, the upper end surface of the flow control unit 12 is separated from the upper plate 113 of the AICD valve, and the fluid in the flow guide channel 111 can flow out through the inner hole 121 of the flow control unit 12; when the flow control unit 12 is located at the second position, the upper end surface of the flow control unit 12 abuts against the upper plate 113 of the AICD valve, thereby closing the inner hole 121 of the flow control unit 12 and preventing the fluid from flowing through the inner hole 121 of the flow control unit 12.
[0037] Specifically, as shown in Figure 4 Under the positive bottom hole differential pressure, the produced fluid in the wellbore flows into the inside of the AICD valve from the wellbore through the flow guide channel 111, pushes the flow control unit 12 to the first position, and the produced fluid can pass between the upper part of the flow control unit 12 and the upper plate 113 of the AICD valve, and finally flows through the inner hole 121 of the flow control unit 12 into the water control screen pipe or the center pipe string. Figure 5 When the user injects high-pressure fluid into the center pipe string at the wellhead, the reverse bottom hole differential pressure is formed on both sides of the AICD valve, the high-pressure fluid injected into the center pipe string flows reversely in the AICD valve, and under the action of the fluid and the reverse bottom hole differential pressure, the flow control unit 12 moves upward until the upper end surface abuts against the upper plate 113 of the AICD valve, at this time, the reverse pressure of the fluid from the inside of the center pipe string further acts on the lower end surface of the flow control unit 12, thereby more firmly pressing the flow control unit 12 upward against the upper plate 113 of the AICD valve, closing the inner hole 121 of the flow control unit 12, and finally preventing the fluid from flowing through the inner hole 121 of the flow control unit 12.
[0038] As an optional implementation, the AICD valve 1 with the anti-backflow function further comprises a detachable valve seat 13, which is annular in structure and arranged in the annular space between the inner wall of the flow guide channel 111 and the outer wall of the flow control unit 12, for limiting the movement of the flow control unit 12 in the axial direction only; the bottom of the valve seat 13 is further provided with a first annular positioning table 131, and the inner diameter of the first positioning table 131 is greater than the inner diameter of the flow control unit 12 and less than the outer diameter of the flow control unit 12.
[0039] Specifically, the valve seat 13 is arranged for the following purposes: first, to position the circumference of the flow control unit 12 and limit the movement of the flow control unit 12 in the axial direction only; second, to support the bottom of the flow control unit 12 through the first annular positioning table 131 extending towards the axial center, and to reasonably set the inner diameter of the first positioning table 131 to achieve the purpose of not hindering the fluid flow and exposing part of the annular structure of the lower end surface of the flow control unit 12, so that the reverse bottom hole pressure difference can push the flow control unit 12 to move upwards; third, the valve seat 13 is designed to be detachable, and users can replace the flow control unit 12 of different types (flow control capacity) before the water control screen pipe is lowered into the well, so as to meet the differentiated needs of different downhole conditions. Preferably, the valve seat 13 is installed in the liquid outlet hole 112 through a threaded fixing mode, so as to be installed or disassembled.
[0040] As an optional implementation, the bottom of the valve seat 13 is further provided with a second annular positioning table 132, and the outer diameter of the second positioning table 132 is greater than the diameter in the flow guide channel 111.
[0041] Specifically, the second positioning table 132 extends from the bottom of the valve seat 13 to the circumferential outside. The second positioning table 132 is arranged to provide positioning function when the valve seat 13 is assembled. For example, when the second positioning table 132 contacts the lower plate 114, it is considered that the valve seat 13 is installed in place when the user operates the valve seat 13 to be installed in the liquid outlet hole 112 in a threaded manner.
[0042] The embodiment provides an AICD valve with an anti-backflow function, which is installed on a water control screen pipe and used in a downhole environment, and is beneficial to accurately control the reverse pressure difference at each position in the central pipe column and generate a higher reverse bottom hole pressure difference at a deeper position in the wellbore.
[0043] Embodiment 2:
[0044] Another AICD valve 1 with an anti-backflow function is given in the embodiment, which is installed on a water control screen pipe and used in a downhole environment, and is beneficial to accurately control the reverse pressure difference at each position in the central pipe column and generate a higher reverse bottom hole pressure difference at a deeper position in the wellbore. Figures 6 to 8As shown, the valve body 11 and the flow control unit 12 of the AICD valve 1 are basically the same as those of the embodiment 1, and the difference is only that the flow control unit 12 is a cylindrical structure coaxially arranged in the liquid outlet hole 112, and the outer diameter of the flow control unit 12 is consistent with the diameter of the liquid outlet hole 112; the upper plate 113 is further provided with a valve cover 14, and the lower surface of the valve cover 14 is a planar structure; when the flow control unit 12 is in the first position, the upper end surface of the flow control unit 12 is separated from the lower surface of the valve cover 14, and the fluid in the flow guide channel 111 can flow out through the inner hole 121 of the flow control unit 12; when the flow control unit 12 is in the second position, the flow control unit 12 abuts against the lower surface of the valve cover 14, which closes the inner hole 121 of the flow control unit 12 and prevents the fluid from flowing through the inner hole 121 of the flow control unit 12. As shown in Figure 7 and Figure 8 As shown, the position of the flow control unit 12 and the specific schematic of the internal fluid flow under the conditions of the positive and negative bottom hole differential pressure of the AICD valve.
[0045] Specifically, the difference between the embodiment 2 and the embodiment 1 is that the valve body 14 arranged on the lower plate 114 for disassembling and replacing the flow control unit 12 in the embodiment 1 is replaced by the valve cover 14 arranged on the upper plate 113, which also provides a working condition for replacing the flow control unit 12. Specifically, the outer diameter of the flow control unit 12 is consistent with the diameter of the liquid outlet hole 112, and can only move axially under the circumferential limitation of the liquid outlet hole 112; the valve cover 14 is located at the upper part of the flow control unit 12, and the lower surface of the valve cover 14 cooperates with the upper surface of the flow control unit 12 to realize the opening or closing of the inner hole 121 of the flow control unit 12.
[0046] As an optional embodiment, the bottom of the liquid outlet hole 112 is further provided with a third annular positioning table 113, and the inner diameter of the third annular positioning table 113 is greater than the inner diameter of the flow control unit 12 and less than the outer diameter of the flow control unit 12.
[0047] The purpose of arranging the third annular positioning table 113 is similar to that of arranging the first annular positioning table 131, which is to support the bottom of the flow control unit 12, and also to realize that the fluid can flow through and the lower end surface ring structure of the flow control unit 12 is properly exposed by reasonably arranging the inner diameter of the first positioning table 131, so that the negative bottom hole differential pressure can drive the flow control unit 12 to move upward.
[0048] As an optional embodiment, the valve cover 14 is detachably arranged on the upper plate 113, and the diameter of the main part of the valve cover 14 is greater than the outer diameter of the flow control unit 12.
[0049] Specifically, the purpose of the detachable design of the valve cover 14 is similar to that of the detachable design of the valve seat 13. Users can replace the flow control unit 12 with different models (flow control capabilities) before lowering the water control screen pipe into the well, according to different flow control requirements, to meet the differentiated needs of different downhole conditions. Preferably, the valve cover 14 is installed in the center of the upper plate 113 by a threaded fixing method for easy installation or removal.
[0050] As an optional implementation, the upper part of the valve cover 14 is further provided with a fourth annular positioning platform 141, the outer diameter of which is larger than the diameter of the main body of the valve cover 14.
[0051] Specifically, the purpose of setting the fourth annular positioning platform 141 is to provide a positioning function for assembling the valve cover 14. For example, when the user operates the valve cover 14 to install it in the center position of the upper plate 113 by means of thread, it is considered to be installed in place when the fourth annular positioning platform 141 contacts the upper plate 113.
[0052] As an optional implementation, the valve cover 14 is also provided with a hexagonal countersunk hole 142 in the center of the upper part.
[0053] Specifically, the purpose of providing the hexagonal countersunk hole 142 is also to facilitate the assembly of the valve cover 14. Users can insert a hexagonal wrench into the hexagonal countersunk hole 142 to install or remove the valve cover 14 by rotation.
[0054] This embodiment provides an AICD valve with anti-backflow function, which has the same technical effect as Embodiment 1.
[0055] Example 3:
[0056] A water control screen pipe with anti-backflow function, such as Figure 9 As shown, the water control screen tube includes a water control screen tube body 2, and an AICD valve with anti-backflow function as described in Embodiment 1 or Embodiment 2 is installed on the water control screen tube body 2.
[0057] Specifically, the AICD valve is installed on the side wall of the base pipe inside the water control screen body 2. One end of the AICD valve's flow channel 111, which communicates with the side wall, is located outside the base pipe. The liquid outlet 112 communicates with the inside of the base pipe, thereby achieving communication between the inside and outside of the base pipe through the AICD valve. When a positive bottomhole pressure differential exists, the produced fluid in the wellbore annulus enters the interior of the base pipe of the screen body 2 through the AICD valve. When a reverse bottomhole pressure differential exists, the flow control unit 12 inside the AICD valve closes the AICD valve, preventing the fluid in the base pipe from entering the wellbore annulus through the AICD valve.
[0058] The water control screen pipe with the anti-flow function is used in the well, and is beneficial to accurately control the reverse pressure difference of each position of the central pipe column and generate a higher reverse bottom hole pressure difference at a deeper position in the wellbore.
[0059] The above is a further detailed description of the utility model in combination with specific preferred embodiments, and the specific implementation of the utility model cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the utility model belongs, without departing from the concept of the utility model, a number of simple deductions or substitutions can be made, and all of them should be regarded as belonging to the protection scope of the utility model.
Claims
1. An AICD valve with anti-backflow function, comprising a valve body, a flow guide channel and a liquid outlet hole are arranged inside the valve body, one end of the flow guide channel is communicated with the side wall of the valve body, and the other end is communicated with the liquid outlet hole, characterized in that: The flow control unit is further provided in the liquid outlet hole. 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 flow channel from flowing out through the liquid outlet hole. When the bottom hole pressure difference is negative, the flow control unit is located at the second position and closes the liquid outlet hole, thereby preventing the fluid in the flow channel from flowing out through the liquid outlet hole.
2. The AICD valve with anti-backflow function according to claim 1, characterized in that: The flow control unit is a cylindrical structure coaxially arranged in the liquid outlet hole. When the flow control unit is located at the first position, the upper end surface of the flow control unit is separated from the upper plate of the AICD valve, and the fluid in the flow channel can flow out through the inner hole 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 abuts against the upper plate of the AICD valve, closing the inner hole of the flow control unit and preventing the fluid from flowing through the inner hole of the flow control unit.
3. The AICD valve with anti-backflow function according to claim 2, characterized in that: Further comprising a detachable valve seat, which is an annular structure arranged in the annular space between the inner wall of the flow channel and the outer wall of the flow control unit, for limiting the movement of the flow control unit along the axial direction; the bottom of the valve seat is further provided with a first annular positioning platform, and the inner diameter of the first annular positioning platform is greater than the inner diameter of the flow control unit and less than the outer diameter of the flow control unit.
4. The AICD valve with anti-backflow function according to claim 3, characterized in that: The bottom of the valve seat is further provided with a second annular positioning platform, and the outer diameter of the second annular positioning platform is greater than the diameter in the flow channel.
5. The AICD valve with anti-backflow function according to claim 2, characterized in that: The flow control unit is a cylindrical structure coaxially arranged in the liquid outlet hole, and the outer diameter of the flow control unit is consistent with the diameter of the liquid outlet hole; the upper plate is further provided with a valve cover, and the lower surface of the valve cover is a planar structure; When the flow control unit is located at the first position, the upper end surface of the flow control unit is separated from the lower surface of the valve cover, and the fluid in the flow channel can flow out through the inner hole of the flow control unit; When the flow control unit is located at the second position, the flow control unit abuts against the lower surface of the valve cover, closing the inner hole of the flow control unit and preventing the fluid from flowing through the inner hole of the flow control unit.
6. The AICD valve with anti-backflow function according to claim 5, characterized in that: The bottom of the liquid outlet hole is further provided with a third annular positioning platform, and the inner diameter of the third annular positioning platform is greater than the inner diameter of the flow control unit and less than the outer diameter of the flow control unit.
7. The AICD valve with anti-backflow function according to claim 6, characterized in that: The valve cover is detachably arranged on the upper plate, and the diameter of the main body part of the valve cover is greater than the outer diameter of the flow control unit.
8. The AICD valve with anti-backflow function according to claim 7, characterized in that: The upper part of the valve cover is further provided with a fourth annular positioning platform, and the outer diameter of the fourth annular positioning platform is greater than the diameter of the main body part of the valve cover.
9. The AICD valve with anti-backflow function according to claim 8, characterized in that: The upper part of the valve cover is further provided with a hexagonal counterbore.
10. A water control screen pipe with anti-backflow function, characterized in that: The water control screen pipe is provided with the AICD valve with anti-backflow function as claimed in any one of claims 1-9.