Expansion type water injection packer capable of backwashing well

Abstract

The invention belongs to the field of oil field injection and production matching tools, and particularly relates to an expanding type water injection packer capable of backwashing a well. The expanding type water injection packer capable of backwashing the well comprises a central pipe and a rubber sleeve assembly, wherein the upper end and the lower end of the rubber sleeve assembly are connected with an upper sealing sliding sleeve and a lower sealing sliding sleeve respectively; during setting, the rubber sleeve assembly is located at the upper stroke limiting position, and a rubber sleeve setting cavity is defined by the center pipe, the upper sealing sliding sleeve and the rubber sleeve assembly. During unsealing, the rubber sleeve assembly is located at the lower stroke limiting position, and a pressure relief cavity is defined by the center pipe, the upper sealing sliding sleeve, the rubber sleeve assembly and the lower sealing sliding sleeve. An upper pressure transmitting hole communicated with the rubber sleeve setting cavity is formed in the center pipe, a check valve for maintaining pressure of the rubber sleeve setting cavity is arranged on the upper pressure transmitting hole, and a lower pressure transmitting hole used for transmitting pressure and pushing the rubber sleeve assembly to move upwards is further formed in the center pipe. The water injection packer has the functions of inverse well flushing, water injection setting and locking, unblocking is not conducted when oil pipe pressure reduction or injection stopping is conducted, and interlayer fluid channeling is prevented.

Description

Technical Field

[0001] The invention belongs to the field of oilfield injection and production supporting tools, and particularly relates to an expandable water injection packer capable of backwashing wells. Background Art

[0002] As oilfields enter the later stages of development, casing damage in water injection wells is becoming increasingly severe, and the number of damaged wells is increasing year by year. Re-cementing water injection well casing damage with small casing can effectively address casing damage and leakage. This approach offers advantages such as a short construction period, low investment, high performance, and low development costs, and holds great promise for future applications.

[0003] In order to support the injection construction of secondary cementing small casing wells, the application publication date is May 5, 2023, and the application publication number is CN11606012A. A small-diameter expandable packer is disclosed, including a center tube with a central through hole, the upper and lower ends of the center tube are respectively connected to the oil pipe upper joint and the oil pipe lower joint, and the outer sleeve of the center tube is covered with a rubber cylinder assembly, which consists of a rubber cylinder (i.e., an expandable rubber cylinder) and a rubber cylinder upper joint (i.e., an upper rubber cylinder seat) and a rubber cylinder lower joint (lower rubber cylinder seat) respectively fixedly connected to the upper and lower ends of the rubber cylinder. The upper joint is sealed to the upper joint of the tubing, and the lower joint of the rubber sleeve is sealed to the lower joint of the tubing. This creates a rubber sleeve sealing cavity between the rubber sleeve assembly and the central tube. The upper and lower ends of the central tube are provided with upper and lower water holes (i.e., upper pressure-uploading holes) that connect to the rubber sleeve sealing cavity. During water injection into the tubing, water enters the rubber sleeve sealing cavity through the upper and lower water holes on the central tube, causing the rubber sleeve to expand and seal. When injection is stopped, the pressure in the central tube drops, and the water in the rubber sleeve sealing cavity is returned to the central tube through the upper and lower water holes, causing the rubber sleeve to reset and unseal. This small-diameter expandable packer has a compact radial structure and can meet the construction requirements of stratified water injection, stratified acidizing, and channeling detection in secondary cementing small-cased wells.

[0004] The construction process characteristics of the above-mentioned small-diameter expandable packer are that it is set during water injection and unsealed when injection is stopped, and backwashing operations can be carried out. However, during actual water injection construction, water injection pressure fluctuations or the need to stop injection are often encountered. At this time, the water injection packer will automatically unseal due to the pressure reduction or suspension of the oil pipeline, causing interlayer crossflow and affecting the oil field injection development effect. Summary of the Invention

[0005] The purpose of the present invention is to provide an expandable water injection packer capable of backwashing wells. On the basis of having the functions of repeated setting and backwashing, the present invention solves the problem that the existing water injection packer is automatically unsealed when the oil pipe is depressurized or injection is stopped, causing interlayer crossflow.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The camshaft of the embodiment of the present invention is a kind of expandable water injection packer for backwash well, comprising a center tube connected with the upper and lower joints, and a rubber cylinder assembly sleeved on the center tube, wherein the upper and lower ends of the rubber cylinder assembly are respectively connected with the upper sealing sleeve and the lower sealing sleeve, and the upper and lower sealing sleeves are both provided with an inner sealing ring platform and a limit mechanism for cooperating with the upper and lower joints to limit their upper and lower strokes; when the rubber cylinder assembly is sealed, it is located at the upper stroke limit position, and the rubber cylinder sealing cavity is surrounded by the center tube, the upper sealing sleeve and the rubber cylinder assembly; when the rubber cylinder assembly is unsealed, it is located at the lower stroke limit position, and the pressure relief cavity is surrounded by the center tube, the upper sealing sleeve, the rubber cylinder assembly and the lower sealing sleeve; the center tube is provided with an upload pressure hole connected with the rubber cylinder sealing cavity, the upload pressure hole is provided with a check valve for maintaining the pressure of the rubber cylinder sealing cavity, and the center tube is also provided with a lower pressure transmission hole for transmitting pressure and pushing the rubber cylinder assembly upward.

[0008] The present invention belongs to an improved invention, which provides a one-way valve at the upper pressure-transmitting hole. When the water injection pressure is greater than the opening pressure of the one-way valve, the liquid in the center pipe enters the rubber sleeve sealing cavity through the upper pressure-transmitting hole, causing the rubber sleeve to expand and seal. When the oil pipe is depressurized or injection is stopped, the pressure in the center pipe is less than the opening pressure of the one-way valve. The one-way valve blocks the upper pressure-transmitting hole to achieve sealing and prevent interlayer crossflow. When backwashing the well, the working fluid pushes the upper sealing sleeve, the rubber sleeve assembly and the lower sealing sleeve downward from the oil casing annulus, the pressure in the rubber sleeve sealing cavity is released, and the rubber sleeve is reset to achieve unsealing and backwashing the well. When re-sealing, the pressure pushes the lower sealing sleeve, the rubber sleeve assembly and the upper sealing sleeve upward through the lower pressure-transmitting hole, reforming the rubber sleeve sealing cavity (sealing cavity), and the water injection sealing and locking can be achieved again.

[0009] The construction process characteristics of the backwashable well expandable water injection packer of the present invention are that it is automatically sealed during water injection and is not unsealed when the oil pipe pressure is reduced or injection is stopped, so as to prevent interlayer crossflow; it is unsealed during backwashing and re-sealed after water injection is resumed. It is more suitable for oil field injection construction, prevents interlayer crossflow, effectively solves the interlayer contradiction that becomes increasingly prominent due to casing deformation, meets the requirements of fine water injection in oil fields, and effectively improves the water injection development effect in the later stage of oil field development.

[0010] Preferably, the center tube is provided with a main body section and a reduced diameter section connected up and down. The upper sealing sleeve slides upward to the upper stroke limit, and the lower end of the rubber cylinder assembly is sealed with the main body section of the center tube; the lower sealing sleeve slides downward to the lower stroke limit, and the lower end of the rubber cylinder assembly slides downward from the main body section of the center tube to the reduced diameter section. A pressure relief hole connected to the oil casing annulus is provided on the lower sealing sleeve above its inner sealing ring platform.

[0011] Further preferably, the upper sealing sleeve is provided with a liquid inlet hole located above the inner sealing ring platform for supplying liquid when backwashing the well.

[0012] Preferably, the inner sealing ring platform of the upper sealing sleeve is arranged at its middle section, and the upper joint is provided with a limiting step which cooperates with the upper section of the upper sealing sleeve.

[0013] Preferably, the upper end surface of the lower joint is limitedly matched with the lower end surface of the inner sealing ring platform of the lower sealing sleeve.

[0014] Preferably, an annular groove is provided on the central tube at a position corresponding to the upper pressure-transmitting hole, and the one-flow valve includes a rubber sleeve adapted to the annular groove.

[0015] Preferably, the rubber cylinder assembly includes an expandable rubber cylinder, an upper rubber cylinder seat, and a lower rubber cylinder seat. The upper rubber cylinder seat has an inner hole adapted to the upper portion of the expandable rubber cylinder. The inner hole of the upper rubber cylinder seat is a stepped hole that is smaller at the top and larger at the bottom.

[0016] Further preferably, the lower rubber cylinder seat has an inner hole adapted to the lower portion of the expandable rubber cylinder, and the inner hole of the lower rubber cylinder seat is a stepped hole that is larger at the top and smaller at the bottom. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of an expandable water injection packer capable of backwashing a well according to an embodiment of the present invention;

[0018] Figure 2 for Figure 1 Partial enlarged view of Ⅰ;

[0019] Figure 3 for Figure 1 Ⅱ partial enlarged view;

[0020] Figure 4 This is a schematic diagram of the expansion setting principle of the present invention;

[0021] Figure 5 This is a schematic diagram of the well-washing and unsealing principle of the present invention;

[0022] Figure 6 for Figure 5 Partial enlarged view of Ⅲ;

[0023] Figure 7 This is a schematic diagram of the principle of returning the upper sealing sleeve to its original position during resetting of the present invention;

[0024] Among them, 1-center tube, 100-main section, 101-reduced diameter section; 2-upper joint, 200-first limiting step; 3-lower joint; 4-upper sealing sleeve, 40-liquid inlet hole; 5-lower sealing sleeve, 50-pressure relief hole; 6-expandable rubber cylinder; 7-upper rubber cylinder seat; 8-lower rubber cylinder seat, 80-second limiting step; 9-rubber cylinder sealing chamber; 10-pressure relief chamber; 11-first sealing ring; 12-return pressure chamber; 13-lower pressure transmission hole; 14-second sealing ring; 15-third sealing ring; 16-fourth sealing ring; 17-fifth sealing ring; 18-upper pressure transmission hole; 19-rubber sleeve, 20-casing. DETAILED DESCRIPTION

[0025] The present invention provides an expandable water injection packer capable of backwashing wells. The packer is set when water injection is required, remains set (locked) when injection is stopped or the oil pipe pressure is reduced, is unsealed during backwashing, and is re-set and locked after water injection is resumed. Thus, the packer can meet the requirements of injection construction in secondary cementing small casing wells, prevent interlayer crossflow, and achieve the purpose of fine water injection in the later stage of oil field development.

[0026] In order to meet the above injection construction requirements, the technical concept of the present invention is to lock the pressure of the rubber cylinder sealing cavity after the rubber cylinder sealing cavity is expanded and sealed to prevent unsealing when injection is stopped or the oil pipe pressure is reduced; when backwashing the well is required to unseal, the rubber cylinder sealing cavity is depressurized to achieve rubber cylinder reset and unsealing; when re-sealing is required to resume water injection, the rubber cylinder sealing cavity is re-formed.

[0027] The present invention realizes the above functions by sliding up and down the upper sealing sleeve, the rubber cylinder assembly, and the lower sealing sleeve which are sleeved on the outside of the central tube, and adding a check valve at the upper pressure upload hole. Before water injection sealing, the check valve is closed. When the water injection pressure of the central tube is greater than the opening pressure of the check valve, the liquid in the central tube enters the rubber cylinder sealing cavity through the upper pressure upload hole, causing the rubber cylinder to expand and seal. After stopping injection or reducing the pressure in the oil pipe, the check valve is closed, and the pressure cannot be transmitted from the upper pressure upload hole, thereby achieving sealing. When backwashing the well is required, the upper sealing sleeve, the rubber cylinder assembly, and the lower sealing sleeve move downward, the rubber cylinder sealing cavity is depressurized, and the rubber cylinder is reset and makes way for the backwash channel. When it is necessary to resume water injection sealing, the upper sealing sleeve, the rubber cylinder assembly, and the lower sealing sleeve move upward again to form the rubber cylinder sealing cavity, and water injection sealing can be realized again.

[0028] The implementation process of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] The embodiment of the backwashable expandable water injection packer of the present invention is as follows Figures 1 to 3 As shown, it includes a central tube 1, an upper joint 2, a lower joint 3, a rubber sleeve assembly, an upper sealing sleeve 4 and a lower sealing sleeve 5.

[0030] Central tube 1 has a central through-hole for water injection. External threads are located at the top and bottom of central tube 1, threadedly connected to upper and lower joints 2 and 3, respectively. Both joints are used to connect to oil pipes. The inner central hole of upper joint 2 is stepped, larger at the top and smaller at the bottom. Internal threads are located at the top and bottom, respectively. The threads at the top connect to the oil pipe, while the threads at the bottom connect to central tube 1.

[0031] The rubber sleeve assembly, upper sealing sleeve 4, and lower sealing sleeve 5 are mounted on the outside of the central tube 1 and slide upward and downward between the upper joint 2 and the lower joint 3. The rubber sleeve assembly includes an expandable rubber sleeve 6, an upper rubber sleeve seat 7, and a lower rubber sleeve seat 8. The expandable rubber sleeve 6 provides deformation and expansion functions. The upper and lower rubber sleeve seats 7 and 8 are made of a non-deformable material and are fixedly connected to the upper and lower parts of the expandable rubber sleeve 6, respectively. The upper sealing sleeve 4 is connected to the upper end of the upper rubber sleeve seat 7 and cooperates with the upper joint 2 for upward positioning. The lower sealing sleeve 5 is connected to the lower end of the lower rubber sleeve seat 8 and cooperates with the lower joint 3 for downward positioning.

[0032] The present invention primarily utilizes the upward and downward sliding motion of the rubber sleeve assembly, upper sealing sleeve 4, and lower sealing sleeve 5 to construct a rubber sleeve setting chamber 9 and a pressure relief chamber 10, thereby enabling switching between setting and unsetting states. The rubber sleeve setting chamber 9 is a sealed cavity structure that can be pressurized, causing the expandable rubber sleeve 6 to expand and deform, thereby sealing the oil casing annulus and achieving setting. The pressure relief chamber 10 communicates with the oil casing annulus, guiding the expandable rubber sleeve 6 to reset and freeing up the annulus for backwashing the well.

[0033] The rubber cartridge assembly, upper sealing sleeve 4, and lower sealing sleeve 5 slide upward to the upper travel limit. The center tube 1, upper sealing sleeve 4, and rubber cartridge assembly form a rubber cartridge seating chamber 9. The upper sealing sleeve 4 is equipped with an inner sealing ring platform, which is equipped with a first sealing ring 11. The center tube 1 is provided with a main section 100 and a reduced diameter section 101, which are connected vertically. At the upper travel limit, the lower rubber cartridge seat 8 seals with the main section 100 of the center tube 1. Through the upper and lower sealing between the inner sealing ring platform of the upper sealing sleeve 4 and the lower rubber cartridge seat 8 and the center tube 1, the rubber cartridge seating chamber 9 is formed between the center tube 1, upper sealing sleeve 4, and rubber cartridge assembly. The outer diameter of the center tube reduced diameter section 101 is smaller than that of the main section 100.

[0034] The rubber cartridge assembly, upper sealing sleeve 4, and lower sealing sleeve 5 slide downward to the lower travel limit. The center pipe 1, upper sealing sleeve 4, rubber cartridge assembly, and lower sealing sleeve form a pressure relief chamber 10. At this point, the lower rubber cartridge seat 8 moves downward from the main section 100 of the center pipe 1 to the reduced diameter section 101, releasing the seal between the lower rubber cartridge seat 8 and the center pipe 1. Pressure relief holes 50 provided on the lower sealing sleeve 5 connect the oil casing annulus, relieving pressure.

[0035] As the rubber sleeve assembly, upper sealing sleeve 4, and lower sealing sleeve 5 slide up and down, their own weight provides some downward sliding force. The lower sealing sleeve 5 is equipped with an inner sealing ring, and its lower end seals against the lower connector 3 (forming a return pressure chamber 12 between the center tube 1, lower sealing sleeve 5, and lower connector 3). A lower pressure-transmitting hole 13 is defined in the center tube 1, below the inner sealing ring of the lower sealing sleeve 5. Pressure can propel the lower sealing sleeve 5, the rubber sleeve assembly, and the upper sealing sleeve 4 upward through this hole, providing the upward sliding force.

[0036] The lower end of the upper joint 2 is provided with a first stop step 200 to limit the upward sliding movement of the upper sealing sleeve 4. The upper sealing sleeve 4 is an overall cylindrical structure, with an inner sealing ring platform located in the middle of the cylindrical structure. A liquid inlet hole 40 is provided on the upper sealing sleeve 4 above the inner sealing ring platform. During backwashing, the wash fluid in the casing annulus can be pushed downward by the gap between the upper end of the upper sealing sleeve 4 and the upper joint 2, and through the liquid inlet hole 40, pushing the upper sealing sleeve 4, the rubber sleeve assembly, and the lower sealing sleeve 5 downward.

[0037] The lower sealing sleeve 5 is a cylindrical structure as a whole, and its inner sealing ring platform is arranged in the middle of the cylindrical structure and a second sealing ring 14 is installed on the inner sealing ring platform. The upper end of the lower sealing sleeve 5 is in contact with the lower rubber cylinder seat 8, and the lower end of the lower sealing sleeve 5 is sleeved on the lower joint 3 and sealed with the lower joint 3. A third sealing ring 15 is provided at the sealing joint between the lower joint 3 and the lower sealing sleeve 5.

[0038] The upper end of the upper rubber cylinder seat 7 is provided with an external thread, and the lower end of the upper sealing sleeve 4 is provided with an internal thread that matches the external thread on the upper rubber cylinder seat 7. The upper rubber cylinder seat 7 and the upper sealing sleeve 4 are threadedly connected. A fourth sealing ring 16 is also installed on the upper rubber cylinder seat 7. The fourth sealing ring 16 is disposed between the upper rubber cylinder seat 7 and the upper sealing sleeve 4 and is located below the threaded connection portion. The upper rubber cylinder seat 7 has a stepped inner bore that adapts to the upper surface of the expandable rubber cylinder 6. The stepped inner bore of the upper rubber cylinder seat 7 is smaller at the top and larger at the bottom. The small inner bore section is threadedly connected to the upper end of the expandable rubber cylinder 6, and the large inner bore section is vulcanized and bonded to the corresponding part of the expandable rubber cylinder 6.

[0039] The lower rubber cylinder seat 8 fits over the lower portion of the expandable rubber cylinder 6 and features a stepped inner bore that conforms to the lower surface of the expandable rubber cylinder 6. The stepped inner bore of the lower rubber cylinder seat 8 is larger at the top and smaller at the bottom. The smaller inner bore section is threadedly connected to the lower end of the expandable rubber cylinder 6, while the larger inner bore section is vulcanized and bonded to the corresponding portion of the expandable rubber cylinder 6. A fifth sealing ring 17 is provided on the inner side of the lower end of the lower rubber cylinder seat 8. A second stopper step 80 is provided at the lower end of the lower rubber cylinder seat 8. The upper end of the lower sealing sleeve 5 overlaps this second stopper step 80 and abuts against it.

[0040] The upper rubber cylinder seat 7 and the lower rubber cylinder seat 8 adopt the above structure, which ensures the strength of the two ends of the expandable rubber cylinder 6 and retains the expansion and deformation ability of the middle part of the expandable rubber cylinder 6, thereby ensuring the sealing effect and durability of the expandable rubber cylinder 6.

[0041] An upper pressure upload hole 18 is provided on the center tube 1 below the sealing ring platform in the upper sealing sleeve 4. The upper pressure upload hole 18 is used to transmit the liquid pressure in the center tube 1 to the rubber cylinder sealing chamber 9. The upper pressure upload hole 18 is provided with a one-way valve. The one-way valve allows the liquid in the center tube 1 to pass through the upper pressure upload hole 18 from the inside to the outside when the opening pressure is greater than the opening pressure, and does not allow the liquid in the rubber cylinder sealing chamber 9 to flow back into the center tube 1 from the outside to the inside. In this embodiment, an annular groove is provided on the center tube 1 corresponding to the position of the upper pressure upload hole, and the one-way valve includes a rubber sleeve 19 embedded in the annular groove. The rubber sleeve 19 is elastic, and its axial length is slightly shorter than the axial length of the annular groove of the center tube 1, and its free inner diameter is slightly smaller than the outer diameter of the center tube 1 at the annular groove of the center tube 1. The pressure in the center tube 1 pushes open the rubber sleeve 19 through the upper pressure-transmitting hole 18 and enters the rubber cylinder sealing chamber 9, causing the expandable rubber cylinder 6 to expand and deform outward and be sealed; when injection is stopped, the rubber sleeve 19 retracts and closes the upper pressure-transmitting hole 18 under its elastic force, keeping the pressure in the rubber cylinder sealing chamber 9 stable and not dropping, so that the setting state of the expandable rubber cylinder 6 can be maintained.

[0042] The typical working state of the backwashable expandable water injection packer of this embodiment is described below.

[0043] Expansion setting process:

[0044] like Figure 4 As shown, during use in the well, the upper joint 2 is connected to the oil pipe, and pressure is applied from the oil pipe. The pressure pushes the rubber sleeve 19 through the upper pressure-transmitting hole 18 into the rubber sleeve sealing cavity 9 surrounded by the upper sealing sleeve 4, the center pipe 1, the upper rubber sleeve seat 7, the expandable rubber sleeve 6, and the lower rubber sleeve seat 8. The expandable rubber sleeve 6 expands and seals the oil casing annulus to complete the sealing.

[0045] Locking process:

[0046] When the oil pipe is depressurized or injection is stopped, the pressure in the rubber sleeve sealing chamber 9 is higher than the pressure in the center pipe 1, the rubber sleeve 19 is tightly attached to the center pipe 1 and seals the upper pressure-transmitting hole 18, and the sealed expandable rubber sleeve 6 is in a locked state.

[0047] Well washing process:

[0048] like Figure 5 、 Figure 6As shown, the oil pipe pressure is released, and the well washing fluid is pumped into the oil-casing annulus between the oil pipe and the casing 20, pushing the upper sealing sleeve 4, the upper rubber cylinder seat 7, the expandable rubber cylinder 6, and the lower rubber cylinder seat 8 mounted on the central pipe to move downward. When the fifth sealing ring 17 at the lower end of the lower rubber cylinder seat 8 moves down to the reduced diameter section 101 of the central pipe 1, the seal is released, the pressure in the rubber cylinder sealing cavity 9 is released, the expandable rubber cylinder 6 retracts and is unsealed, and the well washing fluid flows through the annular space between the expandable rubber cylinder 6 and the casing 20, enters the oil pipe from the bottom of the pipe string and returns to the ground.

[0049] Re-seat:

[0050] like Figure 4 、 Figure 7 As shown, after the well washing is completed, the oil pipe is pressurized, and the pressure enters the return pressure chamber 12 through the lower pressure transmission hole 13 on the central pipe 1, pushing the lower sealing sleeve 5 upward, pushing the lower rubber cylinder seat 8, the expansion rubber cylinder 6, the upper rubber cylinder seat 7, and the upper sealing sleeve 4 upward, and the fifth sealing ring 17 at the lower end of the lower rubber cylinder seat 8 moves up to above the reduced diameter section 101 of the central pipe 1, reforming the rubber cylinder seating chamber 9, and the pressure pushes the rubber sleeve 19 into the rubber cylinder seating chamber 9 through the upper pressure transmission hole 18, and the expansion rubber cylinder 6 expands to reseal the oil casing annulus to complete the seating and lock it.

Claims

1. A backwashable expandable water injection packer, comprising a central tube connected to upper and lower joints, and a rubber sleeve assembly sleeved on the central tube, characterized in that: The upper and lower ends of the rubber cylinder assembly are respectively connected to an upper sealing sleeve and a lower sealing sleeve, and the upper sealing sleeve and the lower sealing sleeve are both provided with an inner sealing ring platform and a limit mechanism for cooperating with the upper and lower joints to limit their upper and lower strokes; when sealing, the rubber cylinder assembly is located at the upper stroke limit position, and the rubber cylinder sealing cavity is surrounded by the center tube, the upper sealing sleeve and the rubber cylinder assembly; when unsealing, the rubber cylinder assembly is located at the lower stroke limit position, and the pressure relief cavity is surrounded by the center tube, the upper sealing sleeve, the rubber cylinder assembly and the lower sealing sleeve; the center tube is provided with an upload pressure hole connected to the rubber cylinder sealing cavity, the upload pressure hole is provided with a check valve for maintaining pressure in the rubber cylinder sealing cavity, and the center tube is also provided with a lower pressure transmission hole for transmitting pressure and pushing the rubber cylinder assembly upward.

2. The backwashable expandable water injection packer according to claim 1, characterized in that: The center tube is provided with a main body section and a reduced diameter section connected in upper and lower parts. The upper sealing sleeve slides upward to the upper stroke limit, and the lower end of the rubber cylinder assembly is sealed with the main body section of the center tube; the lower sealing sleeve slides downward to the lower stroke limit, and the lower end of the rubber cylinder assembly slides downward from the main body section of the center tube to the reduced diameter section. A pressure relief hole connected to the oil casing annulus is provided on the lower sealing sleeve above its inner sealing ring platform.

3. The backwashable expandable water injection packer according to claim 2, characterized in that: A liquid inlet hole for supplying liquid when backwashing the well is provided on the upper sealing sleeve above the inner sealing ring platform.

4. The backwashable expandable water injection packer according to claim 1, characterized in that: The inner sealing ring platform of the upper sealing sleeve is arranged in its middle section, and the upper joint is provided with a limiting step which cooperates with the upper section of the upper sealing sleeve.

5. The backwashable expandable water injection packer according to claim 1, characterized in that: The upper end surface of the lower joint is limitedly matched with the lower end surface of the inner sealing ring platform of the lower sealing sleeve.

6. The backwashable expandable water injection packer according to claim 1, characterized in that: An annular groove is provided on the central tube at a position corresponding to the upper pressure-transmitting hole, and the one-flow valve includes a rubber sleeve adapted to the annular groove.

7. The backwashable expandable water injection packer according to claim 1, characterized in that: The rubber cylinder assembly includes an expandable rubber cylinder, an upper rubber cylinder seat, and a lower rubber cylinder seat. The upper rubber cylinder seat has an inner hole adapted to the upper portion of the expandable rubber cylinder. The inner hole of the upper rubber cylinder seat is a stepped hole with a smaller upper portion and a larger lower portion.

8. The backwashable expandable water injection packer according to claim 7, characterized in that: The lower rubber cylinder seat has an inner hole adapted to the lower portion of the expandable rubber cylinder, and the inner hole of the lower rubber cylinder seat is a stepped hole with a larger upper portion and a smaller lower portion.

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