A downhole circulation device with fixed water injection string backwash function and backwash method

Abstract

The present invention belongs to the technical field of oil and gas field production, gas production and water injection, and discloses a downhole circulation device and backwashing method with a fixed water injection pipe string backwashing function. Clean water enters the well washing channel in the eccentric working cylinder from the annulus, passes through the hanger from the inside of the sealing module, and forms a well washing channel; the hydraulic control fluid enters the hydraulic control piston chamber from the hydraulic control pipeline, and the hydraulic control piston overcomes the pressure of the spring and moves downward, and the eccentric backwashing channel opens. The hydraulic control piston provided by the present invention has an opening pressure of the well washing channel that does not change with the change of the water injection pressure, and always maintains opening and closing at the designed pressure, and has no additional requirements for the pressure of the production well. The eccentric working cylinder provided by the present invention ensures the inner diameter of the pipe string, so that it can meet the requirements of normal water injection pipe string segmentation and stratification, as well as the pipe string strength requirements. The design of the eccentric backwash channel greatly increases the well washing discharge volume, improves the cleaning ability and entrainment capacity, and reduces the requirements for ground facilities.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field oil production, gas production and water injection, and in particular relates to a downhole circulation device with a fixed water injection pipe string backwash function and a backwash method. Background Art

[0002] Currently, the fixed sand control and water injection strings used in various oil fields have the problem of difficulty in backwashing or even inability to wash the well. During the water injection process, as the injection time continues to increase, impurities in the water gradually block the channel, resulting in water injection difficulties and even pump stoppage and production suspension. If cleaning is required, all or part of the string in the well needs to be removed, which requires the use of large equipment and several days, and the cost ranges from hundreds of thousands to millions.

[0003] The above analysis reveals the following problems and drawbacks of the existing technology: The existing fixed water injection string lacks a backwash function, causing it to clog the channel during cleaning, impacting subsequent production. Furthermore, cleaning the existing fixed water injection string is time-consuming and labor-intensive, resulting in high cleaning costs. Summary of the Invention

[0004] In order to overcome the problems existing in the related art, the embodiments disclosed in the present invention provide a downhole circulation device and a backwash method with a fixed water injection string backwash function.

[0005] The technical solution is as follows: a downhole circulation backwashing method with a fixed water injection string backwashing function, comprising:

[0006] Clean water enters the well washing channel in the eccentric mandrel from the annulus, passes through the hanger from the inside of the sealing module, and forms a well washing channel;

[0007] The hydraulic control fluid enters the hydraulic control piston chamber from the hydraulic control pipeline, the hydraulic control piston overcomes the pressure of the spring and moves downward, and the eccentric backwash channel opens.

[0008] In one embodiment, before clean water enters the well washing channel in the eccentric working cylinder from the annulus, an annular pressure test is required. After the pump is started to the design pressure and the pressure is maintained constant, the eccentric backwash channel is opened, and the well washing fluid enters from the annulus, passes through the annulus of several packers and water distributors, enters the oil pipe and returns to the surface.

[0009] Connect the assembled downhole circulation device with fixed water injection string backwash function and lower it to the designed depth, complete the docking with the hanger, adjust the string, put in the tubing hanger, sit on the wellhead, lead the hydraulic control line out of the wellhead sealing hole, connect it to the ground control device, and connect the pressure pump.

[0010] In one embodiment, the ground control device is used to control the pressure of the hydraulic control fluid, so that the hydraulic control fluid enters the hydraulic control piston chamber from the hydraulic control pipeline, the hydraulic control piston moves downward against the pressure of the spring, and the eccentric backwash channel opens. The control of the pressure of the hydraulic control fluid collects the downward movement distance of the spring and the opening state of the eccentric backwash channel in real time, and regulates the pressure of the hydraulic control fluid according to the opening state of the eccentric backwash channel, specifically comprising the following steps:

[0011] The first step is to obtain the downward movement distance of the spring and the opening status of the eccentric backwash channel during the pressure stabilization execution cycle of the hydraulic control fluid. The downward movement distance of the spring is expressed as the spring's demand for downward movement pressure, specifically the spring's demand for the hydraulic control flow rate and hydraulic control flow rate. The opening status of the eccentric backwash channel is expressed as the hydraulic control fluid pressure stabilization triggering pressure pump frequency increase value l th and the dynamic adaptive operating frequency acceleration difference V th ;

[0012] The second step is to detect the hydraulic control adjustment state and exchange information with the adjacent ones, and to adjust the hydraulic control adjustment amount l and the pressure of the hydraulic control fluid to stabilize the pressure pump frequency l. th Compare and calculate the hydraulic control adjustment variance V of each and adjacent areas according to the hydraulic control adjustment variance function. th And V>V th When triggering the pressure adjustment of the hydraulic control fluid;

[0013] The third step is to select the target in the adjacent area, and the hydraulic control adjustment amount l≤l th The neighboring cells of the target are selected and prioritized according to the target physical resource block occupancy rate;

[0014] The fourth step is to select the target in order of priority, select the pressure value to switch to the selected target, and perform hydraulic control adjustment and transfer;

[0015] Step 5: The pressure of the hydraulic control fluid is stable and the judgment ends. When the hydraulic control adjustment amount l≤l th Or if hydraulic control adjustment transfer is performed on all targets, the pressure stabilization process of the hydraulic control fluid is completed. Otherwise, the process returns to step 4 and selects the next target for hydraulic control adjustment transfer according to the target priority.

[0016] In the first step, the dynamic adaptive operation frequency acceleration difference V th , represents the intention of the operating frequency acceleration to stabilize the pressure of the hydraulic control fluid. When the overall hydraulic control adjustment is high, the pressure decreases, and when the overall hydraulic control adjustment is low, the pressure increases. The expression is:

[0017] V th =exp(-αE l )+C

[0018] Among them, El is the mean value of the hydraulic control adjustment in the current and adjacent areas, the decay rate of the α control function, C is a positive constant, to prevent V th The decay to zero results in the hydraulic control adjustments of each network being exactly the same, which represents the maximum tolerance for the imbalance of hydraulic control adjustments and reflects the opening status of the eccentric backwash channel;

[0019] In the second step, the hydraulic control adjustment state is detected, and information is exchanged with the adjacent ones. The spring utility mean is calculated according to the hydraulic control adjustment variance function formula; the spring utility function formula is expressed as:

[0020]

[0021] Among them, L m and L0 are the current delay of the spring and the maximum distance that the spring can currently receive, R m and R0 are respectively the current speed of the spring and the minimum speed required for the spring to run at present, u i is the utility function for a specific material attribute, expressed as follows:

[0022]

[0023] Where x and x0 are the state value and spring demand value respectively, η o and σ o This is to make the function range in [0,1] and satisfy u when x=x0 i =0.5 set the pressure parameters and scaling parameters.

[0024] Another object of the present invention is to provide a downhole circulation device with a fixed water injection string backwash function, which implements the downhole circulation backwash method with a fixed water injection string backwash function, and the device comprises:

[0025] The hydraulic control piston is used to control the fluid entering from the hydraulic control line, overcome the pressure of the spring and move downward, and the eccentric backwash channel is opened;

[0026] The eccentric working cylinder is used to meet the requirements of normal water injection string segmentation and stratification, and form an eccentric backwash channel;

[0027] The eccentric backwash channel is used to utilize the injected clean water to enter the annulus, form backwash pressure, and clean the impurities in the annulus.

[0028] It also includes a pressure differential piston inner cylinder, wherein the upper and lower ends of the pressure differential piston inner cylinder are respectively installed with a sealing upper joint and a piston outer cylinder, the lower end of the piston outer cylinder is connected to a variable buckle joint through a lower core shaft, and the outer lower end of the piston outer cylinder is installed with a sealing cylinder core shaft;

[0029] The outer side of the pressure difference piston inner cylinder is sheathed with a spring outer cylinder, a spring is installed inside the spring outer cylinder, and a spring pressure cap is installed on the upper end of the spring through a retaining pin;

[0030] A hydraulic control pipeline is installed on the outside of the piston outer cylinder through a sealing joint, and the lower end of the hydraulic control pipeline is located on the inner side of the sealing cylinder core shaft;

[0031] Two spring adjustment rings are arranged inside the spring outer cylinder and are respectively located at two ends of the spring.

[0032] In one embodiment, first sealing rings are respectively installed at the contact positions between the two ends of the spring outer tube and the pressure differential piston inner tube and the piston outer tube;

[0033] A second sealing ring, a third sealing ring and a vulcanized anti-slip component are installed at the contact position between the pressure difference piston inner cylinder and the piston outer cylinder.

[0034] In one embodiment, two retaining rings are installed on the outer side of the sealing cylinder core shaft, a guide shoe is installed on the lower end of the outer side of the sealing cylinder core shaft, and a fourth sealing ring is installed between the sealing cylinder core shaft and the guide shoe;

[0035] An NPT plug is installed on the outside of the piston outer cylinder.

[0036] In one embodiment, a prefabricated hole plug and a reserved hole joint are installed in the middle of the piston outer cylinder;

[0037] The retaining ring comprises a sealing unit rigid body and a sealing rubber which are arranged at intervals, and the ends of the sealing unit rigid body form a positioning short circuit.

[0038] Another object of the present invention is to provide an oil and gas field oil and gas production water injection equipment, which implements the downhole circulation backwashing method with the fixed water injection string backwashing function.

[0039] Combining all the above technical solutions, the advantages and positive effects of the present invention are as follows: The present invention provides a downhole circulation device with a fixed water injection string backwash function. By activating a hand pump on the surface, the fluid channel is opened via a hydraulic control line to perform a thorough backwash. After the operation is completed, the hand pump at the wellhead is released to resume normal water injection production. The device is simple, reliable, and inexpensive, requiring no additional equipment.

[0040] The hydraulically controlled piston provided by the present invention has a well-washing channel opening pressure that does not change with changes in the water injection pressure, and always maintains opening and closing at the designed pressure, without any additional requirements for the pressure of the production well. The eccentric working cylinder provided by the present invention ensures the internal diameter of the pipe string, so that it can meet the requirements of normal water injection pipe string segmentation and stratification, as well as the pipe string strength requirements. The design of the eccentric backwash channel greatly increases the well-washing discharge volume, improves the cleaning ability and entrainment capacity, and reduces the requirements for ground facilities. The device body provided by the present invention does not have special coupling threads, so it has a larger space and is suitable for higher strength and pressure requirements.

[0041] The vulcanized seal design provided by the present invention is more wear-resistant and impact-resistant, allowing for multiple uses, ensuring the tool's service life, shelf life, and safety. The ground control device of the present invention controls the pressure of the hydraulic control fluid, allowing it to flow from the hydraulic control line into the hydraulic control piston chamber. The hydraulic control piston overcomes the pressure of the spring and moves downward, opening the eccentric backwash channel, enabling intelligent control. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure;

[0043] Figure 1 This is a schematic diagram of a downhole circulation device with a fixed water injection string backwash function provided by an embodiment of the present invention;

[0044] Figure 2 This is an overall structural diagram of a downhole circulation device with a fixed water injection string backwash function provided by an embodiment of the present invention;

[0045] Figure 3 This is a partial cutaway diagram of a sealed upper joint connection provided by an embodiment of the present invention;

[0046] Figure 4 This is a partial segmented diagram of the connection of the vulcanized anti-slip component provided by an embodiment of the present invention;

[0047] Figure 5 This is a partial segmented diagram of a retaining ring connection provided by an embodiment of the present invention;

[0048] Figure 6 This is a schematic diagram of an NPT plug provided by an embodiment of the present invention;

[0049] Figure 7 This is a schematic diagram of a pre-hole joint provided by an embodiment of the present invention;

[0050] Figure 8 is a schematic diagram of a hydraulically controlled piston provided by an embodiment of the present invention;

[0051] Figure 9Schematic diagram of an eccentric working cylinder provided by an embodiment of the present invention;

[0052] In the figure: 1. Sealing upper joint; 2. Spring outer tube; 3. First sealing ring; 4. Spring pressure cap; 5. Retaining pin; 6. Spring adjusting ring; 7. Spring; 8. Pressure differential piston inner tube; 9. Second sealing ring; 10. Third sealing ring; 11. Vulcanized anti-slip part; 12. Piston outer tube; 13. Sealing tube core shaft; 14. Lower core shaft; 15. Retaining ring; 16. Fourth sealing ring; 17. Guide shoe; 18. Variable buckle joint; 19. NPT plug; 20. Prefabricated hole plug; 21. Hydraulic control pipeline; 22. Sealing joint; 23. Reserved hole joint; 24. Sealing unit rigid body; 25. Sealing rubber; 26. Positioning short circuit. DETAILED DESCRIPTION

[0053] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0054] In embodiment 1, the present invention provides a downhole circulation device for implementing a backwash function of a fixed water injection string, comprising:

[0055] The hydraulic control piston is used to control the fluid entering from the hydraulic control line, overcome the pressure of the spring 7 and move downward, and the eccentric backwash channel is opened;

[0056] The eccentric working cylinder is used to meet the requirements of normal water injection string segmentation and stratification, and form an eccentric backwash channel;

[0057] The eccentric backwash channel is used to utilize the injected clean water to enter the annulus, form backwash pressure, and clean the impurities in the annulus.

[0058] Specifically, the downhole circulation device with fixed water injection string backwash function includes:

[0059] like Figure 1-Figure 7 As shown, the downhole circulation device with a fixed water injection string backwash function provided by the embodiment of the present invention includes a pressure differential piston inner cylinder 8, the upper and lower ends of which are respectively installed with a sealing upper joint 1 and a piston outer cylinder 12, the lower end of the piston outer cylinder 12 is connected to a variable buckle joint 18 through a lower core shaft 14, and the lower end of the outer side of the piston outer cylinder 12 is installed with a sealing cylinder core shaft 13;

[0060] The outer side of the pressure difference piston inner cylinder 8 is provided with a spring outer cylinder 2, a spring 7 is installed inside the spring outer cylinder 2, and a spring pressure cap 4 is installed on the upper end of the spring 7 through a retaining pin 5;

[0061] A hydraulic control line 21 is installed on the outside of the piston outer cylinder 12 through a sealing joint 22 , and the lower end of the hydraulic control line 21 is located on the inner side of the sealing cylinder core shaft 13 .

[0062] In the embodiment of the present invention, two spring adjustment rings 6 are provided inside the outer tube of the spring 7 and are located at both ends of the spring 7 respectively.

[0063] In the embodiment of the present invention, first sealing rings 3 are respectively installed at the contact positions between the two ends of the spring outer tube 2 and the pressure differential piston inner tube 8 and the piston outer tube 12 .

[0064] In the embodiment of the present invention, the second sealing ring 9 , the third sealing ring 10 and the vulcanized anti-slip component 11 are installed at the contact position between the pressure difference piston inner tube 8 and the piston outer tube 12 .

[0065] In the embodiment of the present invention, two retaining rings 15 are installed on the outer side of the sealing cylinder core shaft 13 , a guide shoe 17 is installed on the lower end of the outer side of the sealing cylinder core shaft 13 , and a fourth sealing ring 16 is installed between the sealing cylinder core shaft 13 and the guide shoe 17 .

[0066] In the embodiment of the present invention, an NPT plug 19 is installed on the outside of the piston outer cylinder 12 .

[0067] In the embodiment of the present invention, a prefabricated hole plug 20 and a reserved hole joint 23 are installed in the middle of the piston outer cylinder 12.

[0068] The retaining ring 15 includes a sealing unit rigid body 24 and a sealing rubber 25 arranged at intervals, and a positioning short circuit 26 is formed at the end of the sealing unit rigid body 24.

[0069] In this embodiment of the present invention, the threads on both ends of the oil pipe are modified to standard dimensions, while the intermediate connecting pipe can use non-standard, coupling-free, direct-connect oil pipe threads. The flow retaining ring 15 can be a metal O-ring to prevent it from falling. The main modification is the mounting structure, with the key being that the spring force of spring 7 must exceed at least the area difference × 10 MPa.

[0070] In Example 2, the present invention provides a downhole circulation backwashing method with a fixed water injection string backwashing function, comprising:

[0071] Clean water enters the eccentric working cylinder from the annulus (such as Figure 9 ) in the well washing channel, passes through the hanger from the inside of the sealing module to form a well washing channel; the hydraulic control fluid enters the hydraulic control piston cavity from the hydraulic control pipeline, and the hydraulic control piston (such as Figure 8 ) overcomes the pressure of spring 7 and moves downward, and the eccentric backwash channel opens.

[0072] Specifically,

[0073] According to the design, the early water injection string including the packer, sealing cylinder, hanger, water distributor, sand control screen and so on is lowered. After the packer is set, the water injection string is pulled out and sent in.

[0074] According to the structure, length and sealing surface size of the water injection string in the early stage, select the appropriate downhole circulation device and various length short-circuits for the deployment depth, connect the assembled downhole circulation device and lower it to the designed depth, complete the docking with the hanger, adjust the string, put in the oil tubing hanger, sit at the wellhead, lead the hydraulic control pipeline out of the wellhead sealing hole, connect it to the ground control device, and connect the pressure pump.

[0075] The ground control device is used to control the pressure of the hydraulic control fluid, so that the hydraulic control fluid enters the hydraulic control piston chamber from the hydraulic control pipeline, and the hydraulic control piston moves downward against the pressure of the spring 7, and the eccentric backwash channel is opened. The control of the pressure of the hydraulic control fluid includes:

[0076] The downward movement distance of the spring 7 and the opening state of the eccentric backwash channel are collected in real time, and the pressure of the hydraulic control fluid is regulated according to the opening state of the eccentric backwash channel. Specifically, the following steps are included:

[0077] The first step is to obtain the downward movement distance of the spring 7 and the opening state of the eccentric backwash channel during the pressure stabilization execution cycle of the hydraulic control fluid. The downward movement distance of the spring 7 is expressed as the downward movement pressure requirement of the spring 7, specifically the requirement of the spring 7 for the hydraulic control flow rate and hydraulic control flow rate. The opening state of the eccentric backwash channel is expressed as the pressure stabilization triggering pressure pump frequency value l of the hydraulic control fluid. th and the dynamic adaptive operating frequency acceleration difference V th ;

[0078] The second step is to detect the hydraulic control adjustment state and exchange information with the adjacent ones, and to adjust the hydraulic control adjustment amount l and the pressure of the hydraulic control fluid to stabilize the pressure pump frequency l. th Compare and calculate the hydraulic control adjustment variance V of each and adjacent areas according to the hydraulic control adjustment variance function. th And V>V th When triggering the pressure adjustment of the hydraulic control fluid;

[0079] The third step is to select the target in the adjacent area, and the hydraulic control adjustment amount l≤l th The neighboring cells of the target are selected and prioritized according to the target physical resource block occupancy rate;

[0080] The fourth step is to select the target in order of priority, select the pressure value to switch to the selected target, and perform hydraulic control adjustment and transfer;

[0081] Step 5: The pressure of the hydraulic control fluid is stable and the judgment ends. When the hydraulic control adjustment amount l≤l thIf all targets have been hydraulically controlled and transferred, the pressure stabilization process of the hydraulically controlled fluid ends. Otherwise, the process returns to step 4 and the next target is selected for hydraulic control and transfer according to the target priority.

[0082] The dynamic adaptive operating frequency acceleration difference V in the first step th , represents the intention of the operating frequency acceleration to stabilize the pressure of the hydraulic control fluid. When the overall hydraulic control adjustment is high, the pressure decreases, and when the overall hydraulic control adjustment is low, the pressure increases, as shown below:

[0083] V th =exp(-αE l )+C

[0084] Among them, E l is the mean value of the hydraulic control adjustment in the current and adjacent areas, the decay rate of the α control function, C is a positive constant, to prevent V th The decay to zero results in the hydraulic control adjustments of each network being exactly the same, which represents the maximum tolerance for the imbalance of hydraulic control adjustments and reflects the opening status of the eccentric backwash channel;

[0085] In the second step, the hydraulic control adjustment state of the self is detected, and information is exchanged with the adjacent ones. The utility mean of spring 7 is calculated according to the hydraulic control adjustment variance function formula. The utility function formula of spring 7 is expressed as:

[0086]

[0087] Among them, L m and L0 are respectively the current delay of spring (7) and the maximum distance that can be received by spring (7). m and R0 are respectively the current speed of spring (7) and the minimum speed required to satisfy the current operation of spring (7), u i is the utility function for a specific material attribute, expressed as follows:

[0088]

[0089] Where x and x0 are the state value and the spring (7) demand value, respectively, η o and σ i This is to make the function range in [0,1] and satisfy u when x=x0 i =0.5 set the pressure parameters and scaling parameters.

[0090] After the annular pressure test, the pump is started to the designed pressure and then maintained. At this point, the backwash channel is opened, and the wellbore fluid enters through the environmental control, passes through the annulus of several packers and water distributors, enters the tubing, and returns to the surface. The display shows that the annular flow channel is open. After the wellbore is completed, the hand pump is depressurized, the channel is closed, and water injection resumes normally.

[0091] In the embodiment of the present invention, the working principle of the downhole circulation device with fixed water injection string backwash function includes:

[0092] The hydraulically controlled piston provided by the present invention has an opening pressure of the well-washing channel that does not change with changes in the water injection pressure, and always maintains opening and closing at the designed pressure, without any additional requirements on the pressure of the production well.

[0093] The eccentric mandrel provided by the present invention ensures the inner diameter of the pipe string, so that it can meet the requirements of normal water injection pipe string segmentation and layering, as well as the requirements of pipe string strength.

[0094] The design of the eccentric backwash channel greatly increases the well washing volume, improves the cleaning ability and entrainment capacity, and reduces the requirements for ground facilities.

[0095] The device body provided by the present invention does not have special coupling threads, so that it has a larger space and is suitable for requirements of higher strength and pressure.

[0096] The design of the vulcanized anti-slip piece provided by the present invention makes the tool more wear-resistant and impact-resistant, and can be used multiple times, thereby ensuring the service life, validity period and safety of the tool.

[0097] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0098] The above description is only a preferred specific implementation method of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A downhole circulation backwashing method with a fixed water injection string backwashing function, characterized in that: The method includes: Clean water enters the well washing channel in the eccentric mandrel from the annulus, passes through the hanger from the inside of the sealing module, and forms a well washing channel; The hydraulic control fluid enters the hydraulic control piston chamber from the hydraulic control pipeline, and the hydraulic control piston overcomes the pressure of the spring (7) and moves downward, and the eccentric backwash channel opens; Before clean water enters the well washing channel in the eccentric working cylinder from the annulus, an annular pressure test is required. After the pump is started to the design pressure and the pressure is maintained constant, the eccentric backwash channel is opened, and the well washing fluid enters from the annulus, passes through the annulus of several packers and water distributors, enters the oil pipe and returns to the surface; Also includes: Connect the assembled downhole circulation device with fixed water injection string backwash function and lower it to the designed depth, complete the docking with the hanger, adjust the string, install the tubing hanger, sit on the wellhead, lead the hydraulic control line out of the wellhead sealing hole, connect it to the ground control device, and connect the pressure pump; The ground control device is used to control the pressure of the hydraulic control fluid, so that the hydraulic control fluid enters the hydraulic control piston chamber from the hydraulic control pipeline, the hydraulic control piston overcomes the pressure of the spring (7) and moves downward, and the eccentric backwash channel is opened. The control of the pressure of the hydraulic control fluid collects the downward movement distance of the spring (7) and the opening state of the eccentric backwash channel in real time, and regulates the pressure of the hydraulic control fluid according to the opening state of the eccentric backwash channel, specifically including the following steps: The first step is to obtain the downward movement distance of the spring (7) and the opening state of the eccentric backwash channel during the pressure stabilization execution cycle of the hydraulic control fluid. The downward movement distance of the spring (7) is expressed as the demand of the spring (7) for the downward movement pressure, specifically the demand of the spring (7) for the hydraulic control flow rate and the hydraulic control flow rate. The opening state of the eccentric backwash channel is expressed as the pressure stabilization triggering pressure pump frequency value of the hydraulic control fluid. and dynamic adaptive operating frequency acceleration difference ; The second step is to detect the hydraulic control adjustment status and exchange information with the adjacent The pressure of the hydraulic control fluid stabilizes the pressure pump frequency increase value Compare and calculate the variance of the hydraulic control adjustment amount of each and adjacent areas according to the hydraulic control adjustment variance function ,when and When triggering the pressure adjustment of the hydraulic control fluid; The third step is to select the target in the adjacent area and adjust the amount of liquid control. The neighboring cells of the target are selected and prioritized according to the target physical resource block occupancy rate; The fourth step is to select the target in order of priority, select the pressure value to switch to the selected target, and perform hydraulic control adjustment and transfer; Step 5: The pressure of the hydraulic control fluid is stable and the judgment is completed. When the hydraulic control adjustment amount Or if hydraulic control adjustment transfer is performed on all targets, the pressure stabilization process of the hydraulic control fluid is completed. Otherwise, the process returns to step 4 and selects the next target for hydraulic control adjustment transfer according to the target priority.

2. A downhole circulation device with a fixed water injection string backwash function, characterized in that: The downhole circulation device implements the downhole circulation backwashing method for the fixed water injection string backwashing function according to claim 1, and the downhole circulation device includes: A hydraulic control piston is used for hydraulic control fluid to enter from the hydraulic control line, overcome the pressure of the spring (7) and move downward, and the eccentric backwash channel is opened; The eccentric working cylinder is used to meet the requirements of normal water injection string segmentation and stratification, and form an eccentric backwash channel; The eccentric backwash channel is used to inject clean water into the annulus to form backwash pressure and clean the impurities in the annulus; It also includes a pressure differential piston inner cylinder (8), wherein the upper and lower ends of the pressure differential piston inner cylinder (8) are respectively provided with a sealing upper joint (1) and a piston outer cylinder (12), the lower end of the piston outer cylinder (12) is connected to a variable buckle joint (18) via a lower core shaft (14), and the outer lower end of the piston outer cylinder (12) is provided with a sealing cylinder core shaft (13); The outer side of the pressure difference piston inner cylinder (8) is provided with a spring outer cylinder (2), a spring (7) is installed inside the spring outer cylinder (2), and a spring pressure cap (4) is installed on the upper end of the spring (7) via a stop pin (5); A hydraulic control line (21) is installed on the outside of the piston outer cylinder (12) through a sealing joint (22), and the lower end of the hydraulic control line (21) is located on the inner side of the sealing cylinder core shaft (13); Two spring adjustment rings (6) are provided inside the outer cylinder of the spring (7), respectively located at the two ends of the spring (7); First sealing rings (3) are respectively installed at the contact positions of the two ends of the spring outer cylinder (2) and the pressure difference piston inner cylinder (8) and the piston outer cylinder (12); A second sealing ring (9), a third sealing ring (10) and a vulcanized anti-slip component (11) are installed at the contact position between the pressure difference piston inner cylinder (8) and the piston outer cylinder (12).

3. The downhole circulation device with fixed water injection string backwash function according to claim 2, characterized in that: Two retaining rings (15) are installed on the outer side of the sealing cylinder core shaft (13), a guide shoe (17) is installed on the lower end of the outer side of the sealing cylinder core shaft (13), and a fourth sealing ring (16) is installed between the sealing cylinder core shaft (13) and the guide shoe (17); An NPT plug (19) is installed on the outside of the piston outer cylinder (12).

4. The downhole circulation device with fixed water injection string backwash function according to claim 3, characterized in that: A prefabricated hole plug (20) and a reserved hole joint (23) are installed in the middle of the piston outer cylinder (12); The retaining ring (15) comprises a sealing unit rigid body (24) and a sealing rubber (25) arranged at intervals, and a positioning short circuit (26) is formed at the end of the sealing unit rigid body (24).

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