Coiled tubing water well multifunctional under-pressure ball seat descaling process pipe column

Abstract

The utility model discloses a multi-functional pressure ball seat descaling process pipe column for a coiled tubing water well, which is characterized in that a water injection pipe column sequentially comprises a screwed plug, a screen pipe, a multi-functional pressure ball seat, a coupling, a water distributor and a water injection packer from bottom to top, the pickling string is provided with a pickling tool, a pickling packer, an inner connector and a coiled tubing from bottom to top, the pickling tool comprises a pickling jacket, an isolation plug is fixed in an upper port of the pickling jacket, a sealing plug is arranged in the middle of the pickling jacket, and organic acid is injected into a space between the isolation plug and the sealing plug; through liquid spraying holes are formed in the circumference of the middle section of the pickling outer sleeve, and inner ports of the liquid spraying holes are sealed by the circumference of the sealing plug. A strong magnetic bar is fixed in a lower inner cavity of the pickling jacket, a baffle is arranged at the bottom of the strong magnetic bar, and the circumference of the baffle is screwed in a lower port of the pickling jacket. According to the scheme, fixed-point acid injection and effective soaking can be achieved, the descaling and dewaxing effects are good, and the backwashing well can effectively flush the conical surface of the ball seat.

Description

Technical Field

[0001] The utility model relates to well repair of water injection wells, in particular to a multifunctional pressure-bearing ball seat descaling process pipe column for continuous oil tubing water wells, belonging to the technical field of pressure-bearing descaling of water injection wells. Background Art

[0002] In view of the long-term service of the water injection pipe string, the pipe wall will be scaled, waxed or attached with dirty oil, causing the test to be blocked and the water nozzle cannot be put in. In the past, the solution was to replace the pipe string. In order to reduce costs and improve efficiency, the application of the continuous tubing pressure descaling technology can well solve the scaling and waxing problems of the pipe string. However, the multifunctional pressure ball seat at the bottom of some water injection wells is lost due to the scaling and waxing of the cone surface or steel ball of the ball seat. Domestic oil fields often use continuous tubing for high-pressure precision flushing, pickling or weighted rod impact to deal with the continued scaling and waxing of the multifunctional pressure ball seat and the check valve. Due to the effect of downhole liquid pressure, the steel ball is sealed on the cone surface of the ball seat, resulting in a dead cavity under the ball seat, and the liquid does not flow. High-pressure flushing, pickling or weighted rod impact cannot act on the steel ball and the cone surface of the seat. The problem of the ball seat not sealing has not been solved, which causes the failure of the packer pipe string or the unclear stratified water injection. It is an inevitable choice to start the pipe string, replace the ball seat, and perform downhole pipe string maintenance.

[0003] To ensure safe production, before the pipe string operation, it is necessary to release the pressure or kill the well, and then carry out the layered water injection pipe string operation. There are many problems with this production method: first, the use of high-density well killing hydraulic wells causes the operation construction cost to rise; second, well killing is easy to pollute the formation and crush the formation; third, the use of pressure release causes the construction period to increase, sometimes it takes 1-2 months, greatly increases the amount of sewage recovery, and the energy of the surrounding oil well formations decreases. At the same time, it breaks the balance of the injection and production well network. It takes time and effort to restore the formation energy again after the operation, and the large pressure difference changes damage the casing. Therefore, there has been no solution to the problem of the ball seat of the water injection well not being sealed.

[0004] To solve the problem of ball seat leakage, conventional ball seats cannot meet the requirements, and special ball seats must be designed to ensure that when flushing, the steel ball leaves the sealing cone surface, the flushing liquid can enter under the sealing cone surface, and the flushing liquid or acid liquid can achieve fixed top pickling.

[0005] At present, the conventional stratified water injection pressure operation process string from bottom to top is: wire plug + screen tube + multifunctional pressure ball seat + water distributor 1 + oil pipe + packer 1 + oil pipe + water distributor 2 + oil pipe + packer 2 + ... + oil pipe + water distributor 3 + oil pipe to wellhead. Take the 73mm oil pipe completion string as an example, the inner diameter of the 73mm oil pipe is 62mm, the inner diameter of the water distributor is 46mm, and the inner diameter of the packer is 60mm-62mm. To achieve ball seat cleaning, conventional oil pipes cannot pass through the 46mm inner diameter water distributor, and only 1.5" continuous oil pipes can be used for operation. The structure of the conventional stratified water injection pressure operation process string does not need to be changed, just replace the conventional multifunctional pressure ball seat with a special multifunctional pressure ball seat.

[0006] The Chinese utility model patent with publication number CN 207974796U discloses a shaft-diameter integrated reciprocating descaling spray gun, including a gun body and a gun head, the gun head is connected to the lower end of the gun body through a short circuit, a round hole is arranged at the center of the end face of the gun head, axial nozzles are evenly distributed around the round hole, radial nozzles are arranged on the side wall of the gun body, a piston is arranged in the gun body, one end of the piston is inserted in the short circuit and sealed with the short circuit, the other end of the piston is inserted in the round hole at the end of the gun body and sealed with the inner wall of the round hole, a liquid hole is arranged on the side of the upper part of the piston, and a spring is installed in the short circuit. This technical solution can only descale the inner wall of the water injection pipe column, and cannot solve the problem of the ball seat not sealing.

[0007] The Chinese utility model patent with publication number CN 211287624U discloses an electric descaling device for oilfield water injection wells, which includes a bridle, a main engine, an eccentric hole descaling nipple and a central channel descaling nipple connected in sequence from top to bottom; the eccentric hole descaling nipple includes an eccentric motor; the top of the eccentric motor is connected to the main engine, and the bottom of the eccentric motor is connected to the eccentric descaling head through an eccentric descaling arm; the upper end of the eccentric descaling arm is slidably connected to the retracting and expanding cam in the eccentric hole descaling nipple. This technical solution can only descale the inner wall of the pipe string, and does not act on the ball seat. Utility Model Content

[0008] The purpose of this section is to summarize some aspects of the embodiments of the utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and utility model name of this application to avoid blurring the purpose of this section, specification abstract and utility model name, and such simplifications or omissions cannot be used to limit the scope of the utility model.

[0009] In view of the above problems and / or the problems existing in the prior art, the present utility model is proposed.

[0010] The primary purpose of the utility model is to overcome the problems existing in the prior art and provide a multifunctional pressurized ball seat descaling process column for a continuous oil tubing water well, which can inject acid at a fixed point so that the organic acid can effectively contact the ball seat and the steel ball, has a good descaling and dewaxing effect, and the backwash well can effectively wash the conical surface of the ball seat.

[0011] In order to solve the above technical problems, the utility model provides a multifunctional scale removal process pipe string for a continuous oil tubing water well with a pressurized ball seat. The water injection pipe string comprises, from bottom to top, a thread plug, a screen tube, a multifunctional pressurized ball seat, a coupling, a water distributor and a water injection packer. A fixed-point pickling pipe string is lowered along the central channel of the water injection pipe string. The fixed-point pickling pipe string is provided with a pickling tool, a pickling packer, an inner connector and a continuous oil tubing from bottom to top. The pickling tool comprises a pickling jacket, an isolation plug is fixed in the upper port of the pickling jacket, a sealing plug is provided in the middle of the pickling jacket, and an organic acid is injected into the space between the isolation plug and the sealing plug; a through-spraying hole is provided on the circumference of the middle section of the pickling jacket, and the inner port of each spraying hole is closed by the circumference of the sealing plug; a strong magnetic rod is fixed to the lower inner cavity of the pickling jacket, a baffle is provided at the bottom of the strong magnetic rod, and the circumference of the baffle is screwed into the lower port of the pickling jacket.

[0012] Furthermore, a balancing liquid hole is provided on the lower circumference of the pickling jacket, and the bottom of the balancing liquid hole is tangent to the top of the strong magnetic rod.

[0013] Furthermore, the lower end surface of the baffle is a concave arc surface.

[0014] Furthermore, the middle section of the sealing plug is fixed in the pickling jacket by sealing plug shear pins, and the upper and lower circumferences of the sealing plug are respectively embedded with sealing plug O-rings to achieve sealing with the inner wall of the pickling jacket, and the inner port of each spray hole is located between the two sealing plug O-rings.

[0015] Furthermore, the multifunctional pressurized ball seat includes a ball seat cylinder, the upper inner cavity of the ball seat cylinder is provided with a throat, a throat lower cone is provided below the throat, and an axially penetrating throat bypass hole is provided on one side of the throat; a ball seat body is fixed to the lower inner cavity of the ball seat cylinder, a bell mouth is provided at the upper end of the center hole of the ball seat body, and a low-density steel ball is sealed on the bell mouth.

[0016] Furthermore, a ball seat lower joint is screwed onto the lower end of the ball seat cylinder, a stopper is fixed below the inner step of the ball seat lower joint via a stopper pin, a push rod is fixed to the center of the upper end surface of the stopper, and the upper end of the push rod extends out of the bell mouth.

[0017] Furthermore, a spiral groove is provided on the inner wall of the center hole of the ball seat body.

[0018] Furthermore, a reduced diameter section is provided on the upper portion of the ball seat body, and a ball seat spring is sleeved on the outer periphery of the reduced diameter section.

[0019] Furthermore, the lower outer boss of the ball seat body abuts against the lower inner step of the ball seat cylinder.

[0020] Furthermore, the pickling packer includes an upper joint and a lower joint of the packer which are screwed together. A compression rubber sleeve is sleeved on the outer periphery of the middle section of the upper joint of the packer. The lower end of the compression rubber sleeve is embedded in the upper end of the lower connecting sleeve. The lower connecting sleeve is sleeved on the outer periphery of the upper joint of the packer. A hydraulic chamber is provided between the middle reduced diameter section of the lower connecting sleeve and the top of the lower joint of the packer. A liquid inlet hole is provided on the lower end side wall of the upper joint of the packer to communicate with the hydraulic chamber.

[0021] Furthermore, the outer edge of the lower end of the lower connecting sleeve extends downward and a limiting pin is installed on the circumference of the lower end, and the inner end of the limiting pin is embedded in the limiting groove of the upper outer wall of the lower joint of the packer.

[0022] Furthermore, the middle inner wall of the lower connecting sleeve is embedded with a lower connecting sleeve upper sealing ring to achieve sealing with the outer wall of the upper joint of the packer, and the upper outer periphery of the lower joint of the packer is embedded with a lower connecting sleeve lower sealing ring to achieve sealing with the inner wall of the lower connecting sleeve.

[0023] Furthermore, a spring sheet is embedded in the compression rubber cylinder, and the spring sheet is in the shape of an arch with a convex middle portion.

[0024] Furthermore, an upper connecting sleeve is rotatably connected to the outer circumference of the upper part of the upper joint of the packer, and the upper end of the compression rubber cylinder is embedded in the annular groove between the upper connecting sleeve and the upper joint of the packer.

[0025] Furthermore, a water distributor 1 is provided above the coupling, a water injection packer 1 is provided above the water distributor 1, a water distributor 2 is provided above the water injection packer 1, a water distributor 2 is provided above the water distributor 2, and a water distributor 3 is provided above the water injection packer 2; the water injection packer 1 is located between the lower water injection layer and the middle water injection layer, and the water injection packer 2 is located between the middle water injection layer and the upper water injection layer.

[0026] Compared with the prior art, the utility model has achieved the following beneficial effects: 1. The organic acid can effectively contact the ball seat and the steel ball to produce a chemical reaction; 2. Acid injection is achieved at a fixed point, the amount of acid used is saved, the chemical reaction is sufficient, and the descaling and dewaxing effect is good; 3. The backwash well can effectively wash the conical surface of the ball seat, effectively preventing or delaying the scaling and waxing of the conical surface of the ball seat and the steel ball. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. The drawings are only provided for reference and explanation, not for limiting the present utility model. Among them:

[0028] Figure 1 It is a stereoscopic diagram of the utility model of a multifunctional descaling process pipe string with a pressurized ball seat for a continuous tubing water well;

[0029] Figure 2 It is a cross-sectional view of the multifunctional pressure ball seat in the utility model;

[0030] Figure 3 It is an enlarged view of the fixed-point pickling column in the utility model;

[0031] Figure 4 It is an enlarged view of the pickling packer in the utility model;

[0032] In the figure: A. Thread plug; B. Screen tube; C. Multifunctional pressure ball seat; D. Coupling; E. Water distributor 1; F. Water injection packer 1; G. Water distributor 2; H. Water injection packer 2; J. Water distributor 3; K. Water injection oil pipe;

[0033] Fixed-point pickling string; L. Pickling tool; M. Pickling packer; N. Inner connector; P. Coiled tubing;

[0034] Multifunctional pressure ball seat C: 1. Ball seat cylinder; 1a. Throat; 1b. Cone surface below the throat; 1c. Throat bypass hole; 2. Ball seat body; 2a. Bell mouth; 2b. Spiral groove; 3. Low-density steel ball; 4. Ball seat lower joint; 5. Ball seat spring; 6. Stopper; 6a. Stopper pin; 7. Ejector rod;

[0035] Pickling tool L: 8. Pickling jacket; 8a. Liquid spray hole; 8b. Balance liquid hole; 9. Isolation plug; 10. Organic acid; 11. Sealing plug; 12. Sealing plug shear pin; 13. Strong magnetic rod; 14. Baffle;

[0036] Pickling packer M: 15. Upper joint of packer; 15a. Liquid inlet hole; 16. Upper connecting sleeve; 17. Compression rubber cylinder; 17a. Spring sheet; 18. Lower connecting sleeve; 18a. Sealing ring on lower connecting sleeve; 19. Limit pin; 20. Lower joint of packer; 20a. Limit groove. DETAILED DESCRIPTION

[0037] In the following description of the utility model, the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the utility model and simplifying the description, and do not mean that the device must have a specific direction.

[0038] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific figures. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0040] like Figures 1 to 4 As shown, the water injection pipe column in the utility model includes, from bottom to top, a thread plug A, a screen tube B, a multifunctional pressure ball seat C, a coupling D, a water distributor, a water injection packer and a water injection oil pipe K. For a multi-layer water injection well, a water distributor E is provided above the coupling D, a water injection packer F is provided above the water distributor E, a water distributor 2G is provided above the water injection packer 1F, a water distributor 2G is provided above the water distributor 2H, and a water distributor 3J is provided above the water injection packer 2H; the water injection packer 1F is located between the lower water injection layer and the middle water injection layer, and the water injection packer 2H is located between the middle water injection layer and the upper water injection layer.

[0041] The multifunctional pressurized ball seat C comprises a ball seat cylinder 1, the upper inner cavity of the ball seat cylinder 1 is provided with a throat 1a, a throat lower cone 1b is provided below the throat 1a, and an axially penetrating throat bypass hole 1c is provided on one side of the throat 1a; when the low-density steel ball 3 blocks the throat 1a, the throat bypass hole 1c can ensure the smooth flow of the center hole.

[0042] The lower inner cavity of the ball seat cylinder 1 is fixed with a ball seat body 2, and the lower outer boss of the ball seat body 2 abuts against the lower inner step of the ball seat cylinder 1 to achieve axial positioning. The upper end of the center hole of the ball seat body is provided with a bell mouth 2a, and a low-density steel ball 3 is set on the bell mouth 2a. The upper part of the ball seat body 2 is provided with a reduced diameter section, and the outer periphery of the reduced diameter section is provided with a ball seat spring 5. The upper end of the ball seat body 2 is more than 1 meter away from the lower conical surface 1b of the throat.

[0043] The lower end of the ball seat cylinder 1 is screwed with the ball seat lower joint 4, and a block 6 is fixed below the inner step of the ball seat lower joint 4 through a block pin 6a, which seals the lower end of the pipe column to ensure safety during the well entry process. A push rod 7 is fixed to the center of the upper end surface of the block 6, and the upper end of the push rod 7 extends from the bell mouth 2a, so that the low-density steel ball 3 is separated from the bell mouth 2a of the ball seat body 2, ensuring that the pressure can be transmitted to the block 6 when the pressure is applied. The water injection pipe column is lowered to the designed position, the wellhead is pressurized, the block pin 6a is cut off, and the block 6 and the push rod 7 fall to the position of the screw plug A. When the multifunctional pressure ball seat C is injected with water, the pressure difference of 1-2MPa pushes the low-density steel ball 3 to compress the ball seat spring 5 and seal it on the bell mouth 2a of the ball seat body 2 to ensure normal water injection.

[0044] A fixed-point pickling string is lowered along the central channel of the water injection string. The fixed-point pickling string is provided with a pickling tool L, a pickling packer M, an inner connector N and a coiled tubing P from bottom to top. The outer diameter of the fixed-point pickling string is small, so it is easy to be lowered along the water injection string. The pickling packer M plays a role of sealing the lower part, and the inner connector N plays a role of connecting the coiled tubing P and the tool.

[0045] The pickling tool L comprises a pickling jacket 8, an isolation plug 9 is fixed in the upper port of the pickling jacket 8, a sealing plug 11 is provided in the middle of the pickling jacket 8, and an organic acid 10 is injected into the space between the isolation plug 9 and the sealing plug 11; the isolation plug 9 serves to isolate the organic acid 10 and to push the plunger when injecting the acid. The middle section of the pickling jacket 8 is provided with a through spray hole 8a, and the inner port of each spray hole 8a is closed by the circumference of the sealing plug 11.

[0046] A strong magnetic rod 13 is fixed to the lower inner cavity of the pickling jacket 8. The strong magnetic rod 13 has a strong attraction force and can absorb the low-density steel ball 3 and separate it from the ball seat body 2.

[0047] The bottom of the strong magnetic bar 13 is provided with a baffle 14, and the circumference of the baffle 14 is screwed into the lower port of the pickling jacket 8. The lower end surface of the baffle 14 is a concave arc surface, and when the strong magnetic bar 13 attracts the low-density steel ball 3, it is stabilized below the concave arc surface of the baffle 14.

[0048] A balancing liquid hole 8b is provided on the lower circumference of the pickling jacket 8, and the bottom of the balancing liquid hole 8b is tangent to the top of the strong magnetic rod 13 to balance the pressure in the oil pipe, so that the shear force of the sealing plug shear nail 12 is accurate, and at the same time, it is convenient to discharge the liquid in the lower cavity of the sealing plug 11 when it moves downward.

[0049] The middle section of the sealing plug 11 is fixed in the pickling jacket 8 by means of sealing plug shear pins 12. The upper and lower circumferences of the sealing plug 11 are respectively embedded with sealing plug O-rings to achieve sealing with the inner wall of the pickling jacket 8. The inner port of each spray hole 8a is located between the two sealing plug O-rings.

[0050] The pickling packer M comprises an upper packer joint 15 and a lower packer joint 20 which are screwed together. A compression rubber sleeve 17 is sleeved on the outer periphery of the middle section of the upper packer joint 15. The lower end of the compression rubber sleeve 17 is embedded in the upper end of a lower connecting sleeve 18. The lower connecting sleeve 18 is sleeved on the outer periphery of the upper packer joint 15. A hydraulic chamber is provided between the middle diameter reduction section of the lower connecting sleeve 18 and the top of the lower packer joint 20. A liquid inlet hole 15a is provided on the lower end side wall of the upper packer joint 15 to communicate with the hydraulic chamber.

[0051] The outer edge of the lower end of the lower connecting sleeve 18 extends downward and a limiting pin 19 is installed on the circumference of the lower end. The inner end of the limiting pin 19 is embedded in the limiting groove 20a of the upper outer wall of the lower joint 20 of the packer.

[0052] The middle inner wall of the lower connecting sleeve 18 is embedded with the lower connecting sleeve upper sealing ring 18a to achieve sealing with the outer wall of the upper joint 15 of the packer, and the upper outer periphery of the lower joint 20 of the packer is embedded with the lower connecting sleeve lower sealing ring to achieve sealing with the inner wall of the lower connecting sleeve 18.

[0053] An upper connecting sleeve 16 is rotatably connected to the outer circumference of the upper portion of the upper joint 15 of the packer, and the upper end of the compression rubber sleeve 17 is embedded in the annular groove between the upper connecting sleeve 16 and the upper joint 15 of the packer.

[0054] Traditional packers cannot meet the function of sealing the oil pipe wall. The compression rubber sleeve 17 is vulcanized together with the lower connecting sleeve 18 and the upper connecting sleeve 16. The limit pin 19 slides along the limit groove 20a. Under the premise of ensuring the sealing effect, the compression stroke of the compression rubber sleeve 17 is limited to avoid the tearing of the compression rubber sleeve 17 under special circumstances, and the sealing of the entire pipe string is not affected. A spring sheet 17a is embedded in the compression rubber sleeve 17. The spring sheet 17a is an arch with a convex middle part. After the pressure is released, the compression rubber sleeve 17 can be quickly restored under the action of the spring sheet 17a.

[0055] Construction method: The fixed-point pickling string goes down along the water injection oil pipe K, passes through each water injection packer and water distributor, and continues to go down. Since the outer diameter of the fixed-point pickling string is smaller than the inner diameter of the throat of the multifunctional pressure ball seat C, it enters the interior of the multifunctional pressure ball seat C, contacts and presses the low-density steel ball 3, and continues to go down, so that the low-density steel ball 3 contacts the flared cone surface of the ball seat body 2, and the entire string reaches the bottom. The fixed-point pickling string is lifted up by 0.5 meters, and the strong magnetic rod 13 attracts the low-density steel ball 3, and the low-density steel ball 3 is at a distance from the lower cone surface 1b of the throat. At this time, the wellhead is pressurized, and the pickling packer M is pressurized through the liquid inlet hole 15a, pushing the lower connecting sleeve 18 to compress the compression rubber cylinder 17 to achieve sealing. The limit pin 19 moves in the limit groove 20a to prevent the compression rubber cylinder 17 from being compressed without limit, ensure the sealing effect, extend the life of the compression rubber cylinder 17, and ensure the sealing of the string.

[0056] Further pressurization cuts off the sealing plug shear pin 12. Under the action of the balance liquid hole 8b, the sealing plug 11 moves downward, and the organic acid 10 is sprayed out from the spray hole 8a and enters the multifunctional pressure ball seat C below the compression rubber cylinder 17. The isolation plug 9 reaches the bottom and continues to pressurize to ensure the sealing of the pickling packer M. The organic acid 10 reacts with the scale and wax on the low-density steel ball 3 and the bell-mouth cone surface of the ball seat body 2 in the multifunctional pressure ball seat C to dissolve the scale and wax. The reaction is maintained for more than 2 hours, and the wellhead is unloaded. Under the action of the spring sheet 17a, the compression rubber cylinder 17 is restored, lifted up and lowered back and forth, and the low-density steel ball 3 hits the cone surface of the bell mouth, further cleaning the scale and wax on the low-density steel ball 3 and the cone surface of the bell mouth. Finally, the scale and wax on the low-density steel ball 3 and the bell-mouth cone surface are flushed by backwashing the well to wash out the dirt and complete the descaling of the multifunctional pressure ball seat C.

[0057] When no water is injected, the ball seat spring 5 returns to its original position, pushing the low-density steel ball 3 upward to ensure that there is a gap between the low-density steel ball 3 and the ball seat body 2. The lower pipe string is connected to the annulus through the multifunctional pressurized ball seat C, which is not a dead cavity, making it easy for the fixed-point pickling pipe string to smoothly descend and enter the multifunctional pressurized ball seat C.

[0058] When backwashing the well, the pressure in the well pushes away the low-density steel ball 3, and the lower conical surface 1b of the throat blocks the low-density steel ball 3 to ensure normal well washing. The inner wall of the center hole of the ball seat body is provided with a spiral groove 2b, which is conducive to the formation of vortex and washes away the scale or wax on the bell-mouth conical surface of the ball seat body.

[0059] The above description is only the preferred feasible embodiment of the utility model, which shows and describes the basic principle, main features and advantages of the utility model, but does not limit the scope of patent protection of the utility model. The technicians in this industry should understand that the utility model is not limited by the above embodiments. In addition to the above embodiments, the utility model can also have other implementation modes without departing from the spirit and scope of the utility model. The utility model will also have various changes and improvements. All technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the utility model. The scope of protection required by the utility model is defined by the attached claims and their equivalents. The technical features not described in the utility model can be achieved by or using existing technologies, which will not be repeated here.

Claims

1. A multifunctional coiled tubing water well descaling process string with pressurized ball seat, the water injection string includes from bottom to top: A thread plug, a screen tube, a multifunctional pressure ball seat, a coupling, a water distributor and a water injection packer, characterized in that: a fixed-point pickling string is lowered along the central channel of the water injection string, and the fixed-point pickling string is provided with a pickling tool, a pickling packer, an inner connector and a continuous oil pipe from bottom to top, the pickling tool comprises a pickling jacket, an isolation plug is fixed in the upper port of the pickling jacket, a sealing plug is provided in the middle of the pickling jacket, and an organic acid is injected into the space between the isolation plug and the sealing plug; the middle section of the pickling jacket is provided with a through spray hole on the circumference, and the inner port of each spray hole is closed by the circumference of the sealing plug; a strong magnetic rod is fixed to the lower inner cavity of the pickling jacket, and a baffle is provided at the bottom of the strong magnetic rod, and the circumference of the baffle is screwed into the lower port of the pickling jacket.

2. The multifunctional coiled tubing water well pressure ball seat descaling process string according to claim 1 is characterized by: A balancing liquid hole is arranged on the lower circumference of the pickling jacket, and the bottom of the balancing liquid hole is tangent to the top of the strong magnetic rod.

3. The multifunctional coiled tubing water well descaling process string with pressurized ball seat according to claim 1 is characterized by: The lower end surface of the baffle is a concave arc surface.

4. The multifunctional coiled tubing water well pressure ball seat descaling process string according to claim 1 is characterized by: The middle section of the sealing plug is fixed in the pickling jacket by sealing plug shear pins, and sealing plug O-rings are respectively embedded in the upper and lower circumferences of the sealing plug to achieve sealing with the inner wall of the pickling jacket, and the inner port of each spray hole is located between the two sealing plug O-rings.

5. The multifunctional coiled tubing water well descaling process string with pressurized ball seat according to claim 1 is characterized by: The multifunctional pressurized ball seat comprises a ball seat cylinder, the upper inner cavity of the ball seat cylinder is provided with a throat, a throat lower cone is provided below the throat, and an axially penetrating throat bypass hole is provided on one side of the throat; a ball seat body is fixed to the lower inner cavity of the ball seat cylinder, a bell mouth is provided at the upper end of the center hole of the ball seat body, and a low-density steel ball is sealed on the bell mouth.

6. The multifunctional coiled tubing water well pressure ball seat descaling process string according to claim 5 is characterized by: A ball seat lower joint is screwed onto the lower end of the ball seat cylinder, a stopper is fixed below the inner step of the ball seat lower joint via a stopper pin, a push rod is fixed to the center of the upper end surface of the stopper, and the upper end of the push rod extends out of the bell mouth.

7. The multifunctional coiled tubing water well pressure ball seat descaling process string according to claim 5 is characterized by: The inner wall of the center hole of the ball seat body is provided with a spiral groove.

8. The multifunctional coiled tubing water well pressure ball seat descaling process string according to claim 5 is characterized by: A reduced diameter section is provided on the upper part of the ball seat body, and a ball seat spring is sleeved on the outer periphery of the reduced diameter section.

9. The multifunctional coiled tubing water well descaling process string with pressurized ball seat according to claim 5 is characterized by: The lower outer boss of the ball seat body abuts against the lower inner step of the ball seat cylinder.

10. The multifunctional coiled tubing water well descaling process string with pressurized ball seat according to claim 7, characterized in that: The pickling packer comprises an upper joint and a lower joint of the packer which are screwed together. A compression rubber sleeve is sleeved on the outer periphery of the middle section of the upper joint of the packer. The lower end of the compression rubber sleeve is embedded in the upper end of the lower connecting sleeve. The lower connecting sleeve is sleeved on the outer periphery of the upper joint of the packer. A hydraulic chamber is provided between the middle reduced diameter section of the lower connecting sleeve and the top of the lower joint of the packer. A liquid inlet hole is provided on the lower end side wall of the upper joint of the packer which communicates with the hydraulic chamber.

11. The multifunctional coiled tubing water well descaling process string with pressurized ball seat according to claim 10, characterized in that: The outer edge of the lower end of the lower connecting sleeve extends downward and a limiting pin is installed on the circumference of the lower end. The inner end of the limiting pin is embedded in the limiting groove of the upper outer wall of the lower joint of the packer.

12. The multifunctional coiled tubing water well descaling process string with pressurized ball seat according to claim 11, characterized in that: The middle inner wall of the lower connecting sleeve is embedded with a lower connecting sleeve upper sealing ring to achieve sealing with the outer wall of the upper joint of the packer, and the upper outer periphery of the lower joint of the packer is embedded with a lower connecting sleeve lower sealing ring to achieve sealing with the inner wall of the lower connecting sleeve.

13. The multifunctional coiled tubing water well descaling process string with pressurized ball seat according to claim 11, characterized in that: A spring sheet is embedded in the compression rubber cylinder, and the spring sheet is in the shape of an arch with a convex middle portion.

14. The multifunctional coiled tubing water well pressure ball seat descaling process string according to claim 11, characterized in that: An upper connecting sleeve is rotatably connected to the outer circumference of the upper part of the upper joint of the packer, and the upper end of the compression rubber cylinder is embedded in the annular groove between the upper connecting sleeve and the upper joint of the packer.

15. The multifunctional coiled tubing water well pressure ball seat descaling process string according to claim 11, characterized in that: A water distributor 1 is provided above the coupling, a water injection packer 1 is provided above the water distributor 1, a water distributor 2 is provided above the water injection packer 1, a water distributor 2 is provided above the water distributor 2, a water injection packer 2 is provided above the water distributor 2, and a water distributor 3 is provided above the water injection packer 2; the water injection packer 1 is located between the lower water injection layer and the middle water injection layer, and the water injection packer 2 is located between the middle water injection layer and the upper water injection layer.

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