Accurate section regulation and control method for immovable string of water injection well

Abstract

The invention provides a water injection well immovable string accurate profile regulation and control method. The method comprises the steps that the position of an operation layer is determined; selecting an injection allocation device corresponding to the operation layer in the fixed pipe column as a standard water injector; according to the positions of the standard water injectors, all the injection allocation devices in the fixed tubular column are divided into a shutdown group and a working group; closing an injection allocation device of the shutdown group; obtaining a plugging device; a plugging device is tripped into the side, close to the bottom of the fixed tubular column, of the standard water injector, so that the plugging device is located between the standard water injector and the adjacent injection allocation device; injection increasing measures are taken on the operation layer; and dissolving the plugging device. The problem that in the prior art, water injection well augmented injection measures are poor in augmented injection effect is solved.

Description

Technical Field

[0001] The invention relates to the field of water injection well development measures in oil fields, and in particular to a method for precise profile control of a fixed pipe string in a water injection well. Background Art

[0002] With the improvement of the level of detailed understanding of small layers, the injection measures of oil fields have gradually changed from general operations to detailed operations. However, it is difficult for fixed-pipe operations such as acidizing and profile adjustment to accurately specify small layers, resulting in the failure to take measures in small layers that need to be taken, and excessive operations in layers that do not need to be taken, resulting in unsatisfactory injection effects in oil and water wells, which seriously restricts the stable production of oil fields. Among the existing injection measures, fixed-pipe diversion acidizing and micro-ball profile adjustment technologies are suitable for large and thick layer injection wells and single-layer wells with uneven water absorption. However, there are problems of accumulation of diverters and micro-balls at the bottom of the well during the operation, which can easily cause thread blockage and water nozzle blockage, and even cause blockage of layers that do not need to be taken, resulting in unnecessary waste and economic losses. In addition, if the upper layer is operated, the water nozzle of the lower layer needs to be closed, resulting in complicated procedures and high operating costs.

[0003] That is to say, the water injection well injection enhancement measures in the prior art have the problem of poor injection effect. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for accurately controlling the profile of a fixed pipe string in a water injection well, so as to solve the problem of poor injection effect of injection measures in the water injection well in the prior art.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a method for precise profile control of a fixed tubular string in a water injection well, comprising: determining the position of an operating layer; selecting an injector corresponding to the operating layer in the fixed tubular string as a standard water injector; dividing all injectors in the fixed tubular string into a shutdown group and a working group according to the position of the standard water injector; closing the injectors in the shutdown group; obtaining a plugger; lowering the plugger to the side of the standard water injector close to the bottom of the fixed tubular string so that the plugger is located between the standard water injector and the adjacent injector; implementing injection measures for the operating layer; and dissolving the plugger.

[0006] Furthermore, in the process of dividing all the injectors in the fixed tubing into a shutdown group and a working group according to the position of the standard water injector, it includes: if the standard water injector is located at the top of all the injectors, all the injectors are in the working group; if the standard water injector is located at the bottom of all the injectors, all the injectors are in the shutdown group; if there are injectors on both sides of the standard water injector, the injector located above the standard water injector is in the shutdown group, and the injector located below the standard water injector is in the working group.

[0007] Furthermore, the process of obtaining the occluder includes: determining the inner diameter of the oil pipe of the fixed pipe string; and selecting the occluder whose outer diameter matches the inner diameter of the oil pipe.

[0008] Furthermore, the process of lowering the plugger to one side of the standard water injector close to the bottom of the fixed pipe string so that the plugger is located between the standard water injector and the adjacent dispenser includes: lowering the plugger into the oil pipe of the fixed pipe string using a cable.

[0009] Furthermore, in the process of lowering the plug into the side of the standard water injector close to the bottom of the fixed pipe column so that the plug is located between the standard water injector and the adjacent water distributor, the process includes: spacing the plug and the standard water injector, and the distance between the plug and the standard water injector is greater than or equal to 3 meters and less than or equal to 8 meters.

[0010] Furthermore, in the process of lowering the plug into the side of the standard water injector close to the bottom of the fixed pipe string so that the plug is located between the standard water injector and the adjacent water dispenser, the process includes: using a magnetic positioning calibration method to determine the position of the plug in the fixed pipe string.

[0011] Furthermore, the injection enhancement measure includes one of acidizing operation and microsphere profile control.

[0012] Furthermore, the occluder is made of water-soluble material.

[0013] Furthermore, the material of the occluder includes one of a metal soluble material, a solid inorganic salt soluble material, and a solid organic soluble material.

[0014] Furthermore, the process of dissolving the plug includes: closing the water injection well and dissolving the plug in water for 18 to 24 hours.

[0015] Furthermore, before determining the position of the operating layer, the process also includes: performing a well-flushing operation on the water injection well.

[0016] Furthermore, after the process of dissolving the plugger, the method further includes: performing a backwash operation on the water injection well.

[0017] By applying the technical solution of the present invention, a method for precise profile control of a fixed tubular string of a water injection well comprises: step S10: determining the position of an operating layer; step S20: selecting an injector corresponding to the operating layer in the fixed tubular string as a standard water injector; step S30: dividing all injectors in the fixed tubular string into a shutdown group and a working group according to the position of the standard water injector; step S40: closing the injector in the shutdown group; step S50: obtaining a plugger; step S60: lowering the plugger to a side of the standard water injector close to the bottom of the fixed tubular string so that the plugger is located between the standard water injector and an adjacent injector; step S70: implementing injection measures for the operating layer; and step S80: dissolving the plugger.

[0018] Through step S10, the position of the operating layer is determined, and the layer that needs the augmentation measures and the ordinary layer that does not need the measures are clearly defined to ensure the augmentation effect. Through steps S20 to S40, the dispenser corresponding to the operating layer, i.e., the standard water injector, is clearly defined, and the dispenser located above the operating layer is divided into the shutdown group to avoid conflicts with the water injection process during the augmentation measures or even blockage of the standard water injector. The dispenser located below the operating layer is divided into the working group, and there is no need to shut down the dispenser of the working group, so that normal water injection work can be maintained, the working time of the augmentation measures is reduced, the efficiency of the augmentation measures is improved, and the water injection work below the working layer is not affected. Through steps S50 to S70, the plugging device is set below the standard water injector and does not exceed the adjacent injector. The profile adjustment can be achieved according to the lowering position of the plugging device, and the plugging device is used to plug the oil pipe of the fixed pipe of the water injection well. In this way, when implementing the augmentation measures, most of the acid or plugging agent under the action of gravity can be effectively prevented from entering the ordinary layer without measures or blocking the plugging wire, thereby improving the augmentation effect on the working layer, avoiding the problem that the measure liquid enters the working layer less and the unblocking radius is limited, resulting in unsatisfactory augmentation effect, and at the same time reducing the steps of closing the injector, shortening the construction time, and avoiding damage to the water nozzle. The plugging device is dissolved through step S80, and the normal water injection work of the water injection well will not be affected after the augmentation measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 A partial structural schematic diagram of a fixed pipe string according to a first embodiment of the present invention is shown;

[0021] Figure 2 A partial structural schematic diagram of a fixed pipe string according to a second embodiment of the present invention is shown;

[0022] Figure 3 A partial structural schematic diagram of a fixed pipe string according to a third embodiment of the present invention is shown;

[0023] Figure 4 A flow chart showing a method for precise profile control of a fixed tubular string in a water injection well according to any optional embodiment of the present invention is shown.

[0024] The above drawings include the following reference numerals:

[0025] 10. Working layer; 11. Ordinary layer; 20. Injection device; 21. Standard water injector; 30. Plug device; 40. Oil pipe. DETAILED DESCRIPTION

[0026] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0028] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present invention.

[0029] In order to solve the problem of poor injection effect of injection measures for water injection wells in the prior art, the present invention provides a method for precise profile control of a fixed pipe string for a water injection well.

[0030] like Figures 1 to 4 As shown, the method for precise profile control of the fixed tubular string of a water injection well includes: step S10: determining the position of the operating layer 10; step S20: selecting the injector 20 corresponding to the operating layer 10 in the fixed tubular string as the standard water injector 21; step S30: dividing all the injectors 20 in the fixed tubular string into a shutdown group and a working group according to the position of the standard water injector 21; step S40: closing the injectors in the shutdown group; step S50: obtaining the plugger 30; step S60: lowering the plugger 30 to the side of the standard water injector 21 close to the bottom of the fixed tubular string, so that the plugger 30 is located between the standard water injector 21 and the adjacent injector 20; step S70: implementing injection measures for the operating layer 10; step S80: dissolving the plugger 30.

[0031] Through step S10, the position of the working layer 10 is determined, and the layer position that needs the augmentation measures and the ordinary layer 11 that does not need the measures are clearly defined to ensure the augmentation effect. Through steps S20 to S40, the dispenser 20 corresponding to the working layer 10, that is, the standard water injector 21, is clearly defined, and the dispenser 20 located above the working layer 10 is divided into the shutdown group to avoid conflicts with the water injection process during the augmentation measures or even blockage of the standard water injector 21. The dispenser 20 located below the working layer 10 is divided into the working group, and the dispenser 20 of the working group does not need to be closed, so that normal water injection work can be maintained, the working time of the augmentation measures is reduced, the efficiency of the augmentation measures is improved, and the water injection work below the working layer 10 is not affected. Through steps S50 to S70, the plugging device 30 is set below the standard water injector 21 and does not exceed the adjacent distributor 20. The profile adjustment can be achieved according to the lowering position of the plugging device 30, and the plugging device 30 is used to plug the oil pipe 40 of the fixed pipe of the water injection well. In this way, when implementing the augmentation measures, most of the measure liquid can be effectively prevented from entering the ordinary layer 11 or plugging the plug under the action of gravity, which does not require measures. The augmentation effect on the working layer 10 is improved, and the problem of less measure liquid entering the working layer 10 and the limited unblocking radius resulting in unsatisfactory augmentation effect is avoided. At the same time, the process of closing the distributor 20 is reduced, the construction time is shortened, and the water nozzle is prevented from being damaged. The plugging device 30 is dissolved through step S80, and the normal water injection work of the water injection well will not be affected after the augmentation measures.

[0032] It should be noted that the standard water injector 21 can be divided into a shutdown group or a working group, and can be selected according to the actual position of the working layer 10.

[0033] Specifically, in the process of dividing all the dispensers 20 in the fixed pipe string into a shutdown group and a working group according to the position of the standard water injector 21, it includes: if the standard water injector 21 is located at the top of all the dispensers 20, all the dispensers 20 are in the working group; if the standard water injector 21 is located at the bottom of all the dispensers 20, all the dispensers 20 are in the shutdown group; if there are dispensers 20 on both sides of the standard water injector 21, the dispenser 20 located above the standard water injector 21 is in the shutdown group, and the dispenser 20 located below the standard water injector 21 is in the working group. That is to say, according to the different relative positional relationships between the working layer 10 and the ordinary layer 11, the relative position of the standard water injector 21 in all the dispensers 20 will also change. If the standard water injector 21 is located at the top of all the dispensers 20, there is no need to close the dispenser 20, and the plug 30 can be directly lowered into the fixed pipe of the water injection well; if the standard water injector 21 is located at the bottom of all the dispensers 20, all the dispensers 20 are closed, and the standard water injector 21 can be closed or opened, but since the position of the standard water injector 21 is too low and the risk of blockage is high, it is preferred to close it to avoid damage to the standard water injector 21. If there are dispensers 20 on both sides of the standard water injector 21, the dispenser 20 located below the standard water injector 21 does not need to be closed and can maintain normal operation.

[0034] Specifically, the process of obtaining the plugger 30 includes: determining the inner diameter of the oil pipe 40 of the fixed pipe string; selecting the plugger 30 whose plugging outer diameter matches the inner diameter of the oil pipe 40. In this way, the plugging effect of the plugger 30 can be ensured, and the prevention and control measures can effectively prevent the plugging of the water nozzle and the accumulation of the bottom of the well.

[0035] Specifically, in the process of lowering the plug 30 to the side of the standard water injector 21 close to the bottom of the fixed pipe string so that the plug 30 is located between the standard water injector 21 and the adjacent dispenser 20, the plug 30 is lowered into the oil pipe 40 of the fixed pipe string using a cable. By lowering the plug 30 using a cable, the stability of the lowering process and the accuracy of the position can be ensured.

[0036] Specifically, in the process of lowering the plug 30 to the side of the standard water injector 21 close to the bottom of the fixed pipe column so that the plug 30 is located between the standard water injector 21 and the adjacent dispenser 20, the plug 30 and the standard water injector 21 are spaced apart, and the distance between the plug 30 and the standard water injector 21 is greater than or equal to 3 meters and less than or equal to 8 meters. The distance between the plug 30 and the standard water injector 21 is limited to greater than or equal to 3 meters to avoid the short distance between the plug 30 and the standard water injector 21, which causes the measure liquid to be unable to fully enter the working layer 10. The distance between the plug 30 and the standard water injector 21 is limited to less than or equal to 8 meters to avoid wasting more measure liquid due to excessive distance.

[0037] Specifically, in the process of lowering the plug 30 to the side of the standard water injector 21 close to the bottom of the fixed pipe string so that the plug 30 is located between the standard water injector 21 and the adjacent dispenser 20, the method includes: using a magnetic positioning calibration method to determine the position of the plug 30 in the fixed pipe string. The magnetic positioning calibration method is conducive to ensuring the position accuracy of the plug 30 and improving the efficiency of setting the plug 30.

[0038] Specifically, the injection enhancement measures include one of acidification operation and microsphere profile control. By adopting different injection enhancement measures in combination with the structure of the water injection well, accurate operation in the working layer 10 can be achieved, and the injection enhancement effect on the working layer 10 can be ensured.

[0039] Specifically, the plug 30 is made of a water-soluble material, which facilitates the removal of the plug 30 after the injection measures are completed to avoid clogging the water injection well.

[0040] Optionally, the material of the occluder 30 includes one of a metal soluble material, a solid inorganic salt soluble material, and a solid organic soluble material.

[0041] Preferably, the occluder 30 is a bidirectional slip structure to ensure good sealing performance.

[0042] Specifically, the process of dissolving the plug 30 includes: closing the water injection well, dissolving the plug 30 in water for 18 to 24 hours, and ensuring that the plug 30 is completely dissolved to avoid clogging the water injection well.

[0043] Specifically, before determining the position of the working layer 10, the process also includes: performing a well cleaning operation on the water injection well to ensure that the inside of the water injection well is usually not blocked.

[0044] Specifically, after the process of dissolving the plugging device 30, the process further includes: performing a backwash operation on the water injection well to avoid blockage caused by the injection process and reduce internal pollution.

[0045] The method for precise profile control of the fixed tubular column of the water injection well disclosed in the present application can prevent thread blockage, accumulation of measure fluid at the bottom of the well, protect the water nozzle, reduce construction procedures, and realize precise profile control of the fixed tubular column of a small layer.

[0046] Embodiment 1

[0047] like Figure 1 As shown, in this embodiment, the standard water injector 21 is located at the top of all the dispensers 20. The dispenser 20 does not need to be closed. The plugging device 30 is directly lowered into the fixed pipe of the water injection well using a cable. The magnetic positioning is calibrated to a position 3 meters below the standard water injector 21. Acidizing or profile control operations are performed on the fixed pipe string.

[0048] Specifically, the occluder 30 is made of aluminum-magnesium soluble metal material, and in step S80 , the occluder 30 is dissolved for 18 hours.

[0049] This embodiment can effectively prevent the majority of acid or plugging agents from entering the common layer 11 due to gravity, resulting in less acid entering the formation of the working layer 10, limited unblocking radius, and unsatisfactory injection effect. At the same time, it reduces the steps of closing the dispenser 20, shortens the construction time, and avoids damage to the water nozzle.

[0050] Embodiment 2

[0051] like Figure 2 As shown, the difference from the first embodiment is that the position of the working layer 10 is different.

[0052] In this embodiment, the water injection wellbore is a conventional pipe string, the standard water injector 21 is located at the bottom of all the dispensers 20, and all the dispensers 20 are closed. Magnetic positioning is used to calibrate to a position 8 meters below the standard water injector 21. The immobile pipe string is diverted for acidification.

[0053] Specifically, the occluder 30 is a solid inorganic salt soluble material, and the occluder 30 has a diameter of 42 mm and a length of 50 mm. In step S80, the occluder 30 is dissolved for 24 hours.

[0054] This embodiment can effectively avoid the problem of plugging of the diverter by the diverter during diversion acidification, which leads to obstruction of on-site construction and increased construction time, and at the same time effectively prevents the water-insoluble temporary plugging agent or diverter from being deposited at the bottom of the well and causing stringing.

[0055] Embodiment 3

[0056] like Figure 3 As shown, the difference from the first embodiment is that the position of the working layer 10 is different.

[0057] In this embodiment, the water injection wellbore is a small diameter pipe string, and both sides of the standard water injector 21 are provided with a dispenser 20. The dispenser 20 located above the standard water injector 21 is in the shutdown group, and the dispenser 20 located below the standard water injector 21 is in the working group. The standard water injector 21 can be closed or opened. Magnetic positioning is used to calibrate to a position 5 meters below the standard water injector 21. Acid or microsphere profile control is performed on the immobile pipe string.

[0058] Specifically, the occluder 30 is a solid organic soluble material, and has a diameter of 35 mm and a length of 50 mm. In step S80, the occluder 30 is dissolved for 18 hours.

[0059] This embodiment can effectively prevent acid or microspheres and other profile control agents from entering the common layer 11, damaging the water nozzle and clogging the common layer 11, and preventing water injection from entering. At the same time, it can effectively prevent microspheres or profile control agents from being deposited at the bottom of the well and causing moving pipe string operations.

[0060] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0061] 1. The position of the working layer 10 is determined through step S10, and the layer that needs injection measures and the common layer 11 that does not need measures are clearly identified to ensure the injection effect.

[0062] 2. Through steps S20 to S40, the dispenser 20 corresponding to the working layer 10, namely the standard water injector 21, is identified, and the dispenser 20 located above the working layer 10 is placed in the shutdown group to avoid conflicts with the water injection process during the augmentation measures or even blockage of the standard water injector 21. The dispenser 20 located below the working layer 10 is placed in the working group. There is no need to shut down the dispenser 20 of the working group, and normal water injection work can be maintained, thereby reducing the working time of the augmentation measures, improving the efficiency of the augmentation measures, and at the same time will not affect the water injection work below the working layer 10.

[0063] 3. Through steps S50 to S70, the plugger 30 is set below the standard water injector 21 and does not exceed the adjacent injector 20. The profile adjustment can be achieved according to the lowering position of the plugger 30, and the plugger 30 is used to plug the oil pipe 40 of the fixed pipe of the water injection well. In this way, when implementing the injection measures, most of the acid or plugging agents can be effectively prevented from entering the ordinary layer 11 or blocking the wire plug due to gravity when the measures are implemented, thereby improving the injection effect on the working layer 10 and avoiding the problem that less measure liquid enters the working layer 10 and the unblocking radius is limited, resulting in unsatisfactory injection effect. At the same time, the steps of closing the injector 20 are reduced, the construction time is shortened, and the water nozzle is avoided from being damaged.

[0064] 4. The plugging device 30 is dissolved in step S80, and the normal water injection work of the water injection well will not be affected after the injection measure.

[0065] 5. The precise profile control method of the fixed tubular column of the water injection well of the present application can prevent the blockage of the thread, the accumulation of the measure fluid at the bottom of the well, protect the water nozzle, reduce the construction process, and realize the precise profile control of the fixed tubular column of the small layer.

[0066] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0067] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0068] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for precise profile control of a fixed pipe string in a water injection well, characterized in that: include: Determining the position of the working layer (10); Selecting the injector (20) corresponding to the working layer (10) in the fixed pipe string as the standard water injector (21); According to the position of the standard water injector (21), all the injectors (20) in the fixed pipe string are divided into a shutdown group and a working group; Closing the dispenser (20) of the shutdown group; Get the occluder (30); The plugging device (30) is lowered into the side of the standard water injector (21) close to the bottom of the fixed pipe string, so that the plugging device (30) is located between the standard water injector (21) and the adjacent dispenser (20); Implementing injection measures on the working layer (10); The occluder (30) is dissolved.

2. The method for precise profile control of a fixed pipe string in a water injection well according to claim 1, characterized in that: The process of dividing all the dispensers (20) in the fixed pipe string into a shutdown group and a work group according to the position of the standard water injector (21) includes: If the standard water injector (21) is located at the top of all the dispensers (20), then all the dispensers (20) are in a working group; If the standard water injector (21) is located at the lower part of all the dispensers (20), then all the dispensers (20) are in the shutdown group; If the standard water injector (21) has the dispenser (20) on both sides, the dispenser (20) located above the standard water injector (21) is in the shutdown group, and the dispenser (20) located below the standard water injector (21) is in the working group.

3. The method for precise cross-section control of a fixed pipe string in a water injection well according to claim 1, characterized in that: The process of obtaining the occluder (30) includes: Determining the inner diameter of the oil pipe (40) of the fixed pipe string; The occluder (30) is selected such that the occluding outer diameter of the occluder (30) matches the inner diameter of the oil pipe (40).

4. The method for precise profile control of a fixed pipe string in a water injection well according to claim 1, characterized in that: The process of lowering the plugging device (30) to the side of the standard water injector (21) close to the bottom of the fixed pipe string so that the plugging device (30) is located between the standard water injector (21) and the adjacent dispenser (20) includes: The plugging device (30) is lowered into the oil pipe (40) of the fixed pipe string using a cable.

5. The method for precise profile control of a fixed pipe string in a water injection well according to claim 1, characterized in that: The process of lowering the plugging device (30) to the side of the standard water injector (21) close to the bottom of the fixed pipe string so that the plugging device (30) is located between the standard water injector (21) and the adjacent dispenser (20) includes: The plugging device (30) and the standard water injector (21) are spaced apart, and the distance between the plugging device (30) and the standard water injector (21) is greater than or equal to 3 meters and less than or equal to 8 meters.

6. The method for precise profile control of a fixed pipe string in a water injection well according to claim 4, characterized in that: The process of lowering the plugging device (30) to the side of the standard water injector (21) close to the bottom of the fixed pipe string so that the plugging device (30) is located between the standard water injector (21) and the adjacent dispenser (20) includes: The position of the occluder (30) placed in the fixed pipe string is determined by means of magnetic positioning calibration.

7. The method for precise profile control of a fixed pipe string in a water injection well according to claim 1, characterized in that: The injection enhancement measure includes one of acidizing operation and microsphere profile control.

8. The method for precise profile control of a fixed pipe string in a water injection well according to any one of claims 1 to 7, characterized in that: The occluder (30) is made of water-soluble material.

9. The method for precise cross-section control of a fixed pipe string in a water injection well according to claim 8, characterized in that: The material of the occluder (30) comprises one of a metal soluble material, a solid inorganic salt soluble material, and a solid organic soluble material.

10. The method for precise profile control of a fixed pipe string in a water injection well according to any one of claims 1 to 7, characterized in that: The process of dissolving the plug (30) includes: closing the water injection well and dissolving the plug (30) in water for 18 to 24 hours.

11. The method for precise profile control of a fixed pipe string in a water injection well according to any one of claims 1 to 7, characterized in that: Before the process of determining the position of the working layer (10), the process also includes: performing a well-flushing operation on the water injection well.

12. The method for precise profile control of a fixed pipe string in a water injection well according to any one of claims 1 to 7, characterized in that: After the process of dissolving the plug (30), the method further comprises: performing a backwash operation on the water injection well.

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