Integrated pipe column for layered acidizing, layered water injection and acid washing and operation method thereof

Abstract

The application discloses an integrated pipe column for layered acidification, layered water injection and pickling and a running method thereof. The pipe column comprises a casing pipe, a tubing pipe, an upper acidification switch, an upper measuring and water distribution device, a packer, a lower measuring and water distribution device, a lower acidification switch and a single flow valve which are sequentially connected in the casing pipe. The upper acidification switch comprises a main body, an upper sliding sleeve and a lower sliding sleeve. The lower acidification switch comprises an upper joint, a plate frame and a lower joint. When running, the upper acidification switch is controlled by a ball pressing mode, the upper and lower measuring and water distribution devices are channels for layered water injection after acidification, the packer seals the casing pipe, the single flow valve is opened or closed by pressure boosting and pressure releasing when acidification is needed, the pipe column is used for acidification in the next turn, and layered water injection is performed in two layers after acidification and layered acidification in two layers. The application realizes all processes by only one turn of pipe column, and shortens the operation construction time.

Description

Technical Field

[0001] This invention relates to a tubing string for improving formation permeability in water injection wells, belonging to the technical field of oilfield stratified acidizing tubing strings. Background Technology

[0002] Layered acidizing is fundamental to resolving inter-layer conflicts and maintaining long-term stable oilfield production. Currently, commonly used layered acidizing tubing mainly consists of packers, non-slippered water distributors, slippered water distributors, and bottom-feeding balls. This has led to a series of tubing strings suitable for multi-layered acidizing, generally focusing on 1-3 layer trial extrusion layered acidizing tubing. Currently, layered trial extrusion acidizing tubing mainly faces the following problems:

[0003] 1. It is impossible to achieve integrated pickling and acidification construction.

[0004] The existing stratified acidification columns and pickling columns are two different types of columns, with high tooling costs and high labor costs.

[0005] 2. Complex construction procedures increase costs.

[0006] The existing stratified acidizing string involves sequentially testing from bottom to top to determine the water absorption index, and then acidizing based on the formation's water absorption. However, if the testing pressure in the lower layer exceeds the well's safety limit, acidizing cannot proceed according to the normal procedure. The already-run string must be removed, and a new acid-washed string must be run to acidify the formation and reduce its water absorption index. Then, the acid-washed string is removed, and an acidizing string is run to perform acidizing.

[0007] Therefore, the existing layered acidification tubing requires additional construction steps for raising and lowering the tubing, which increases the construction time and the labor intensity of workers, thereby increasing the construction cost.

[0008] 3. After the stratified acidification is completed, the stratified acidification tubing must be removed before the stratified water injection tubing can be lowered to perform stratified water injection. This will increase the number of construction steps for removing the tubing, increase the construction time, increase the labor intensity of workers, and thus increase the construction cost.

[0009] Therefore, engineers developed an integrated construction string for layered acidizing and layered water injection, combining the acidizing and water injection strings into one, reducing the number of times the string needs to be pulled up and down, reducing the labor intensity of workers, reducing construction costs, reducing construction time, and increasing the injection volume.

[0010] Existing integrated stratified acidizing and stratified water injection tubing mainly consists of hydraulic anchors, packers, stratified acidizing and water injection devices, setting and injection water distributors, well-washing valves, and sealing and retrieval devices. The construction procedure for this type of integrated stratified acidizing and stratified water injection tubing is as follows:

[0011] (1) Install the integrated completion string for layered acidizing and water injection;

[0012] (2) After the packer is set, continue to increase the pressure until the pressure drops suddenly, open the packer and inject water into the distributor, and test inject the lower layer;

[0013] (3) Acidify the lower layer;

[0014] (4) Insert a sealing retrieval device into the tubing so that the retrieval device enters the stratified acidizing and stratified dispensing device;

[0015] (5) Pressurize the tubing until the pressure drops suddenly, open the stratified acidification stratified injection device, and seal the lower layer;

[0016] (6) Acidify the upper layer;

[0017] (7) Backwash the well to remove residual acid from the wellbore;

[0018] (8) Use the retrieval device to retrieve the core of the layered acidification and layered dispensing device and carry out two-layer layered production.

[0019] The aforementioned tubing string can achieve integrated construction of layered acidification and layered water injection. However, it does not address the integrated acid pickling and acidification process. For example, if the pressure exceeds the safety limit and acid pickling is required during the acidification of the lower layer, the aforementioned tubing string cannot meet the requirements. Furthermore, with the increasing demand for refined water injection, the layered water injection dispenser has been replaced by an integrated measurement and adjustment dispenser. The layered acidification dispenser used in the aforementioned tubing string can only use a hollow water dispenser structure and cannot be used with the integrated measurement and adjustment dispenser. Therefore, using the aforementioned tubing string cannot achieve refined water injection. Summary of the Invention

[0020] The purpose of this invention is to address the shortcomings of existing technologies by providing an integrated tubing string for layered acidizing, layered water injection, and acid washing. This tubing string is installed in water injection wells that require layered acidizing and water injection in two water injection layers, enabling acid washing, two-layer layered acidizing, and two-layer layered water injection to be performed in a single run. This reduces the construction steps of raising and lowering the tubing string, shortens the operation time, reduces the labor intensity of workers, and reduces the operation cost.

[0021] The integrated tubing for layered acidification, layered water injection, and acid washing of the present invention adopts the following technical solution:

[0022] The tubing string includes a casing, within which are arranged, from top to bottom, an oil pipe, an upper acidizing switch, an upper water distributor, a packer, a lower water distributor, a lower acidizing switch, and a check valve. The upper acidizing switch includes a main body, an upper sliding sleeve, and a lower sliding sleeve. The upper sliding sleeve is connected to the main body by a shear pin, and the main body has a connecting hole. The lower sliding sleeve is connected to the lower part of the upper sliding sleeve. The lower acidizing switch includes an upper connector, a plate frame, and a lower connector. The lower connector is connected to the lower part of the upper connector. The plate frame is installed inside the upper connector and above the lower connector. A flap is hinged on the plate frame. The lower connector has a radial injection hole, and the lower end of the lower connector has a flow hole.

[0023] A sealing device is provided between the upper acidification switch and the lower acidification switch.

[0024] An upper retaining ring is installed on the outer wall of the upper sliding sleeve, and a retaining ring groove is provided on the inner wall of the main body. The upper retaining ring is located above the retaining ring groove, which is located above the connecting hole. The upper retaining ring is an elastic circular shape with an opening, allowing the inner and outer diameters of the upper retaining ring to change. When the upper retaining ring is in a free state, its outer diameter is larger than that of the upper sliding sleeve.

[0025] The lower inner diameter of the main body is larger than the outer diameter of the lower sliding sleeve but smaller than the outer diameter of the upper sliding sleeve.

[0026] The lower sliding sleeve is connected to the lower part of the upper sliding sleeve by a blind hole pin, which is opposite to the connecting hole. After the blind hole pin is cut off, the inner hole of the upper sliding sleeve communicates with the connecting hole through the inner hole of the blind hole pin, forming the acid injection channel of the upper acidification switch.

[0027] The lower part of the sliding sleeve is provided with locking teeth so that the sliding sleeve locks with the lower acidification switch after it falls.

[0028] Sealing rings are provided on the inner wall of the main body above and below both the connecting hole and the shear pin.

[0029] A sealing ring is provided between the lower connector and the upper connector, and a sealing device is provided inside the lower connector above the injection hole.

[0030] The flap is hinged to a window on the side wall of the frame by a pin, and a torsion spring is fitted on the pin.

[0031] A lower retaining ring is provided on the inner wall of the lower connector below the injection hole. A baffle is connected to the lower connector below the lower retaining ring, and the flow hole is located on the baffle. The lower retaining ring cooperates with the lower part (the retaining teeth) of the lower sliding sleeve to lock the lower sliding sleeve and prevent it from moving upward.

[0032] The packer, upper and lower water distributors, and check valve are all existing technologies. The packer is an expansion packer. The upper acidizing switch is the channel for acid to enter the upper water injection layer during acidizing. The sliding sleeve of the upper acidizing switch is controlled by a ball-drop pressurization method to open and close it. The upper acidizing switch is also the channel for acid to enter the formation during lower acidizing. During upper acidizing, it is used to intercept the sliding sleeve and seal the lower layer, and it also functions as a check valve in the well completion injection string. The upper and lower water distributors are the channels for stratified water injection after acidizing. The packer expands and seals the casing through differential pressure, dividing the upper and lower water injection layers into two pressure systems. The check valve can open and close. When open, the fluid can flow from top to bottom, providing a channel for acid washing of the lower water injection layer. When closed, it can acidize the lower water injection layer. The check valve is kept open or closed by pressurization and depressurization operations.

[0033] When the above tubing is in use, both the upper and lower water injection layers are connected to the casing (the casing is connected to the upper and lower water injection layers respectively), and the packer is located between the upper and lower water injection layers; when the liquid pressure in the casing is higher than the pressure of the upper and / or lower water injection layers, the liquid in the casing can be injected into the upper and lower water injection layers, and the upper acidizing switch and the lower acidizing switch are in the closed state.

[0034] The operating method of the integrated tubing string for layered acidification, layered water injection, and acid washing of the present invention includes the following steps:

[0035] (1) The pressure of the tubing and casing is balanced by reverse circulation well washing;

[0036] (2) Inject oilfield water into the tubing so that the tubing is filled with oilfield water above the check valve. Increase the pressure and then depressurize to open the check valve. Inject oilfield water into the water layer downwards to test squeeze. If the test squeeze pressure is appropriate, inject acid solution.

[0037] The term "appropriate test extrusion pressure" means that if the maximum test extrusion pressure is lower than the wellhead pressure limit, the fluidity of the acidizing system can be guaranteed. Such a pressure is considered appropriate.

[0038] (3) Acid is injected into the oil pipe. The acid enters the lower water injection layer through the lower acidizing switch. The packer sets and seals the casing so that the acid can only enter the lower water injection layer.

[0039] (4) If the test pressure in step (2) is higher than the pressure that can be acidified, acid washing is required. Depressurize to open the check valve.

[0040] (5) Inject pickling solution into the oil pipe, and after the pressure drops, release the pressure to close the check valve and inject acid into the oil pipe. The acid enters the lower water injection layer through the lower acidification switch (injection hole on the lower acidification switch) to acidify the lower water injection layer.

[0041] (6) After the lower water injection layer acidification is completed, the oil pipe is depressurized and a valve ball is thrown into the oil pipe so that the valve ball sits in the lower sliding sleeve of the upper acidification switch. Pressure is applied and the pressure pushes the lower sliding sleeve down to open the acid injection channel of the upper acidification switch (the inner hole of the upper sliding sleeve is connected to the connecting hole on the main body). The upper acidification switch is connected to the lower water injection layer. At the same time, the lower sliding sleeve moves down to the lower acidification switch to close the lower acidification switch.

[0042] (7) Inject acid into the tubing. The acid enters the casing through the upper acidification switch. The throttling pressure difference causes the packer to seal the casing. The acid enters the upper water injection layer and acidifies the upper water injection layer.

[0043] (8) Put the valve ball into the tubing again, so that the valve ball sits in the upper sliding sleeve of the upper acidizing switch. Pressurize, and the pressure pushes the upper sliding sleeve to cut the shear pin and move downward, closing the upper acidizing switch. Depressurize the tubing, retract the packer, inject the well washing fluid into the casing for reverse circulation to remove acid, and wash out the valve ball sitting in the upper sliding sleeve of the upper acidizing switch. Open the upper and lower water distribution devices, inject water into the tubing, expand the packer to seal the casing, and inject water to the upper and lower water injection layers.

[0044] The beneficial effects of this invention are:

[0045] When high pressure is required during pre-acidification testing necessitates acid washing, the opening or closing of a stable single-flow valve via pressure increase and release allows for acid washing of the tubing in that specific run. After acid washing, the two injection layers are acidified separately. Following this, the lower control unit is lowered, and the upper and lower control water distributors are opened to perform stratified water injection for both layers. All these processes require only one tubing run. Therefore, this invention achieves its objective, resolves inter-layer conflicts, maintains long-term stable stratified acidification in the oilfield, reduces the number of tubing runs, shortens operation time, reduces labor intensity, and lowers operation costs, resulting in significant economic benefits. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the integrated tubular column for layered acidification, layered water injection, and acid washing of the present invention.

[0047] Figure 2 This is a schematic diagram of the structure of the acidification switch in this invention.

[0048] Figure 3 This is a schematic diagram of the lower acidification switch in this invention.

[0049] In the diagram: 1. Oil pipe, 2. Upper acidification switch, 3. Upper water distributor, 4. Packer, 5. Lower water distributor, 6. Lower acidification switch, 7. Stable check valve, 8. Upper water injection layer, 9. Lower water injection layer, 10. Lower water injection layer;

[0050] 301. Main body; 302. Upper retaining ring; 303. Upper sliding sleeve; 304. Upper sealing ring; 305. Blind hole pin; 306. Lower sealing ring; 307. Lower sliding sleeve; 308. Shear pin; 30101. Retaining ring groove; 30102. Connecting hole; 30701. Retaining tooth;

[0051] 701. Upper connector, 702. Pin, 703. Flip plate, 704. Plate frame, 705. Sealing device, 706. Lower retaining ring, 707. Baffle, 708. Lower connector, 70401. Window, 70701. Flow hole, 70801. Injection hole. Detailed Implementation

[0052] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0053] like Figure 1 As shown, the integrated tubing string for layered acidification, layered water injection, and pickling of the present invention includes a casing 1, an oil pipe 2, an upper acidification switch 3, an upper water distributor 4, a packer 5, a lower water distributor 6, a lower acidification switch 7, a stable check valve 8, an upper water injection layer 9, and a lower water injection layer 10 connected to the casing 1.

[0054] The structure of the upper acidification switch 3 is as follows Figure 2 As shown, the system includes a main body 301, an upper sliding sleeve 303, and a lower sliding sleeve 307. Both the upper sliding sleeve 303 and the lower sliding sleeve 307 are housed within the main body 301. The lower inner diameter of the main body 301 is larger than the outer diameter of the lower sliding sleeve 307, and the outer diameter of the upper sliding sleeve 303 is larger than the lower inner diameter of the main body 301. The upper sliding sleeve 303 is fixed within the main body 301 by shear pins 308. The upper outer wall of the upper sliding sleeve 303 has an annular groove in which an upper retaining ring 302 is installed. The upper retaining ring 302 is an elastic circular shape with an opening, allowing its inner and outer diameters to change. When the upper retaining ring 302 is in a free state, its outer diameter is larger than the outer diameter of the upper sliding sleeve 303. The inner wall of the main body 301 is provided with a retaining ring groove 30101 that can accommodate the upper retaining ring 302. The upper retaining ring 302 is located above the retaining ring groove 30101. The main body 301 is provided with a connecting hole 30102, which is located below the retaining ring groove 30101. The lower sliding sleeve 307 is connected to the lower part of the upper sliding sleeve 303 by a blind hole pin 305. The blind hole pin 305 passes through the upper sliding sleeve 303 and is pinned to the lower sliding sleeve 307. The outlet end of the blind hole pin 305 faces outward, and the blind hole pin 305 is opposite to the connecting hole 30102. The lower part of the lower sliding sleeve 307 is provided with a retaining tooth 30701. An upper sealing ring 304 and a lower sealing ring 306 are provided between the upper sliding sleeve 303 and the main body 301. The upper sealing ring 304 is above the connecting hole 30102, and the lower sealing ring 306 is below the connecting hole 30102. The upper sealing ring 304 is below the retaining ring groove 30101, and the shear pin 308 is between the upper sealing ring 304 and the lower sealing ring 306.

[0055] The structure of the lower acidification switch 7 is as follows Figure 3 As shown, it includes an upper connector 701, a plate frame 704, and a lower connector 708. The plate frame 704 is installed inside the upper connector 701 from the lower part. The upper end of the plate frame 704 is limited by the lower end face of the internal shoulder of the upper connector 701. The lower part of the upper connector 701 is connected to the upper part of the lower connector 708, and a sealing ring is provided at the connection. A window 70401 is radially opened on the side wall of the plate frame 704. Figure 3 The device consists of two symmetrical windows 70401. Each window 70401 has a flap 703 mounted on it via a pin 702. A torsion spring is fitted onto the pin 702, keeping the flap 703 horizontal. The upper surface of the window 70401 prevents the flap 703 from flipping upwards, thus blocking the valve ball and preventing it from being washed away by the fluid flow. The flap 703 can also flip downwards into the window 70401. A sealing device 705 is located on the upper inner part of the lower connector 708. The sealing device 705 uses a conventional mechanical seal and can cooperate with the sliding sleeve 307 for sealing. The lower connector 708 has a radial injection hole 70801 located below the sealing device 705. A lower retaining ring 706 is provided on the inner wall of the lower connector 708 below the injection hole 70801. The lower retaining ring 706 can cooperate with the retaining teeth 30701 at the lower part of the sliding sleeve 307 to lock the sliding sleeve 307 and prevent it from moving upward. The lower retaining ring 706 is elastically circular and has an opening. A baffle 707 is connected inside the lower connector 708 below the lower retaining ring 706. The baffle 707 is used to block the lower retaining ring 706 and prevent it from falling. The lower end face of the baffle 707 has flow holes 70701 distributed to allow the injection liquid to pass through.

[0056] The water distribution device is existing technology, with a built-in measuring instrument and movable water nozzle. The upper water distribution device 4 and the lower water distribution device 6 are channels for stratified water injection after acidification, and the water injection volume can be adjusted by rotating the measuring instrument to open the movable water nozzle.

[0057] The packer 5 adopts an expansion packer of existing technology, which expands the sealing sleeve 1 through pressure difference, so that the upper water injection layer 9 and the lower water injection layer 10 are divided into two pressure systems.

[0058] The one-way valve 8 is a stable one-way valve, which is existing technology and can be opened and closed. When the one-way valve 8 is open, the liquid can flow from top to bottom, providing a channel for acid washing of the lower water layer 10. When the one-way valve 8 is closed, it can acidify the lower water layer 10. The stable one-way valve 8 can be kept in the open or closed state by pressurizing and depressurizing operations.

[0059] The aforementioned integrated tubing string is used in injection wells where the upper injection layer 9 and the lower injection layer 10 require stratified acidizing and stratified water injection. A single run of tubing string can achieve acid washing, two-layer stratified acidizing, and two-layer stratified water injection. The specific process is described below.

[0060] Oil pipe 2, upper acidification switch 3, upper water distributor 4, packer 5, lower water distributor 6, lower acidification switch 7, and stable check valve 8 are connected in sequence and lowered into casing 1. Packer 5 is located between upper water injection layer 9 and lower water injection layer 10.

[0061] When the liquid pressure inside the casing 1 is higher than the pressure of the upper water injection layer 9 and the lower water injection layer 10, the liquid inside the casing 1 can be injected into the upper water injection layer 9 and the lower water injection layer 10, and the upper acidification switch 3 and the lower acidification switch 7 are in the closed state.

[0062] The operation process of the above-mentioned device of the present invention is as follows.

[0063] (1) Connect tubing 2, upper acidizing switch 3, upper water distribution device 4, packer 5, lower water distribution device 6, lower acidizing switch 7, and stable single-flow valve 8 in sequence and lower them into casing 1. Install the acidizing wellhead device and perform reverse circulation well washing to balance the pressure of tubing 2 and casing 1.

[0064] (2) Inject oilfield water into tubing 2 to fill the tubing string above check valve 8 with oilfield water. Increase the pressure and then depressurize to open check valve 8 in reverse. Inject oilfield water into water layer 10 downwards. If the pressure of the test squeeze is appropriate (e.g., if the maximum pressure of the test squeeze is lower than the wellhead pressure limit, and the fluidity of the acidizing system can be guaranteed, such pressure is considered appropriate), then inject acid.

[0065] (3) Acid is injected into the oil pipe 2. The acid enters the lower water injection layer 10 through the injection hole 70801 on the lower acidification switch 7. Since the injection hole 70801 has a throttling effect, the packer 5 sets and seals the sleeve 1, so that the acid can only enter the lower water injection layer 10.

[0066] (4) If the test extrusion pressure in (2) above is higher than the pressure that can be acidified, acid washing is required, and the pressure is released to open the check valve 8.

[0067] (5) Inject pickling solution into oil pipe 2, and after the pressure drops, release the pressure to close the check valve 8 and inject acid into oil pipe 2. The acid enters the lower water injection layer 10 through the injection hole 70801 on the lower acidification switch 7 to acidify the lower water injection layer 10.

[0068] (6) After the lower water injection layer 10 is acidified, the oil pipe 2 is depressurized and a valve ball is inserted into the oil pipe 2 so that the valve ball sits on the lower sliding sleeve 307 of the upper acidification switch 3. The pressure pushes the lower sliding sleeve 307 down and cuts off the blind hole pin 305. The cut blind hole pin hole and the connecting hole 30102 are connected to form an acid injection hole. The upper acidification switch 3 is connected to the upper water injection layer 9 through this acid injection hole. At the same time, the lower sliding sleeve 307 goes down to the lower acidification switch 7 and cooperates with the sealing device 705 to seal, so that the lower acidification switch 7 is closed. The retaining teeth at the bottom of the lower sliding sleeve 307 are locked together with the lower retaining ring 706.

[0069] (7) Acid is injected into the oil pipe 2. The acid enters the casing 1 through the cut blind hole pin hole and the connecting hole 30102 (acid injection hole) on the upper acidification switch 3. The throttling pressure difference generated by the connecting hole 30102 causes the packer 5 to seal the casing 1. The acid enters the upper water injection layer 9 and acidifies the upper water injection layer 9.

[0070] (8) The valve ball is dropped into tubing 2 again, so that the ball sits in the upper sliding sleeve 303 of the upper acidizing switch 3. Pressure is applied, and the pressure pushes the upper sliding sleeve 303 to shear the shear pin 308 and move downward. The upper sliding sleeve 303 covers the connecting hole 30102, the tubing 2 is depressurized, the packer 5 is retracted, and the well washing fluid is injected into the casing 1 for reverse circulation acid discharge, and the valve ball on the upper sliding sleeve 303 is washed out. The upper water distributor 4 and the lower water distributor 6 are opened to inject water into tubing 2. Under the throttling effect, the packer 5 expands the sealing casing 1, and the injected water is used to inject water into the upper water injection layer 9 and the lower water injection layer 10 in layers. After the upper sliding sleeve 303 moves downward, the upper retaining ring 302 enters the retaining ring groove 30101 to lock it, and the upper sliding sleeve 303 always covers the connecting hole 30102.

Claims

1. An integrated tubing string for layered acidification, layered water injection, and acid washing, characterized in that: The system includes a casing, within which are arranged, from top to bottom, an oil pipe, an upper acidizing switch, an upper water distributor, a packer, a lower water distributor, a lower acidizing switch, and a check valve. The upper acidizing switch comprises a main body, an upper sliding sleeve, and a lower sliding sleeve. The upper sliding sleeve is connected to the main body via shear pins. The main body has a connecting hole. The lower sliding sleeve is connected to the lower part of the upper sliding sleeve. The lower acidizing switch comprises an upper connector, a plate frame, and a lower connector. The lower connector is connected to the lower part of the upper connector. The plate frame is installed inside the upper connector and above the lower connector. A flap is hinged on the plate frame. The lower connector has a radial injection hole and a flow hole at its lower end. The sealing device can cooperate with the sliding sleeve to seal. An upper retaining ring is installed on the outer wall of the upper sliding sleeve, and a retaining ring groove is provided on the inner wall of the main body. The upper retaining ring is located above the retaining ring groove, and the retaining ring groove is located above the connecting hole. The upper retaining ring is an elastic circular shape with an opening, allowing the inner and outer diameters of the upper retaining ring to change. When the upper retaining ring is in a free state, its outer diameter is larger than that of the upper sliding sleeve. The lower inner diameter of the main body is larger than the outer diameter of the lower sliding sleeve and smaller than the outer diameter of the upper sliding sleeve; The lower part of the sliding sleeve is provided with retaining teeth; The flap is hinged to a window opened on the side wall of the frame by a pin, and a torsion spring is fitted on the pin. A lower retaining ring is provided on the inner wall of the lower connector below the injection hole. The lower retaining ring can cooperate with the retaining teeth at the bottom of the lower sleeve to lock the lower sleeve and prevent it from moving upward. The lower connector has a baffle connected below the lower retaining ring, and the flow passage is located on the baffle.

2. The integrated tubing string for layered acidification, layered water injection, and acid washing according to claim 1, characterized in that: The lower sliding sleeve is connected to the lower part of the upper sliding sleeve by a blind hole pin, and the blind hole pin is opposite to the connecting hole.

3. The integrated tubing string for layered acidification, layered water injection, and acid washing according to claim 1, characterized in that: Sealing rings are provided on the inner wall of the main body above and below both the connecting hole and the shear pin.

4. The integrated tubing string for layered acidification, layered water injection, and acid washing according to claim 1, characterized in that: A sealing ring is provided between the lower connector and the upper connector, and a sealing device is provided inside the lower connector above the injection hole.

5. An operating method for an integrated tubing string employing the layered acidification, layered water injection, and acid washing methods described in any one of claims 1-4, characterized in that, Includes the following steps: (1) The pressure of the tubing and casing is balanced by reverse circulation well washing; (2) Inject oilfield water into the tubing to fill the tubing above the check valve with oilfield water. Increase the pressure and then depressurize to open the check valve. Inject oilfield water downwards into the water layer to test squeeze. If the test squeeze pressure is appropriate, inject acid. The appropriate test squeeze pressure means that the maximum test squeeze pressure is lower than the wellhead pressure limit. (3) Acid is injected into the oil pipe. The acid enters the lower water injection layer through the lower acidizing switch. The packer sets and seals the casing so that the acid can only enter the lower water injection layer. (4) If the test extrusion pressure in step (2) is higher than the pressure that can be acidified, acid washing is required, and the pressure is released to open the check valve; (5) Inject pickling solution into the oil pipe to replace the reservoir soaking and unblocking. After the pressure drops, release the pressure and close the check valve. Inject acid into the oil pipe. The acid enters the lower water injection layer through the lower acidification switch to acidify the lower water injection layer. (6) After the lower water injection layer acidification is completed, the oil pipe is depressurized and a valve ball is thrown into the oil pipe so that the valve ball sits in the lower sleeve of the upper acidification switch. The pressure pushes the lower sleeve down to open the acid injection channel of the upper acidification switch and connect the upper acidification switch with the lower water injection layer. At the same time, the lower sleeve moves down to the lower acidification switch to close the lower acidification switch. (7) Acid is injected into the tubing. The acid enters the casing through the upper acidification switch. The throttling pressure difference causes the packer to seal the casing. The acid enters the upper water injection layer and acidifies the upper water injection layer. (8) Put the valve ball into the tubing again, so that the valve ball sits in the upper sliding sleeve of the upper acidizing switch, pressurize, and the pressure pushes the upper sliding sleeve to cut the shear pin downward, close the upper acidizing switch, depressurize the tubing, retract the packer, inject the well washing fluid into the casing for reverse circulation acid discharge, and wash out the valve ball sitting in the upper sliding sleeve of the upper acidizing switch. Open the upper and lower water distribution devices, inject water into the tubing, expand the packer to seal the casing, and inject water to the upper and lower water injection layers.

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