A downhole delivery tool for solid-free plugging agent and a targeted plugging construction process

Abstract

This invention provides a solid-free plugging agent downhole delivery tool and a targeted plugging construction process. The delivery tool includes a plugging packer and a chemical dosing device connected to the lower end of the plugging packer. The chemical dosing device includes a lower connector, a chemical chamber connection connector, a chemical chamber, and a basket connected sequentially from top to bottom. The bottom of the basket has a release hole from which the chemical is released. This invention utilizes the delivery tool to extrude a solvent-free, single-component, nano-reinforced polyurethane grouting material into the wellbore in a single operation. After the polyurethane grouting material is injected into the leaking layer, under formation pressure, the polymerization rate is slow in the initial stage of the reaction. At this time, the grouting material remains in an oily liquid state and can follow the flowing water to target the leaking location where the pressure suddenly decreases. At this time, the polymerization reaction intensifies, rapidly foaming and encapsulating the surrounding rock mass or fault wall. Simultaneously, the generated carbon dioxide can also propel the grout deeper into the seepage channel, achieving targeted plugging.

Description

Technical Field

[0001] This invention pertains to leakage prevention and plugging in the field of oil and gas field drilling, specifically relating to a downhole delivery tool for a solid-phase plugging agent and a targeted plugging construction process. Background Technology

[0002] Well leakage is a common phenomenon in oil drilling. It can cause huge economic losses to drilling companies and may also lead to safety accidents such as stuck drill, blowout, and well collapse during drilling operations, or even cause wellbore abandonment, seriously affecting the drilling process.

[0003] To effectively address well leakage problems, commonly used inorganic plugging agents in drilling sites often suffer from the problem of slugs that accumulate within fractures, making it difficult to form a dense deposit and susceptible to damage from inrush pressure. Epoxy-based grouting materials, on the other hand, have high resin viscosity, tend to stagnate downhole, and have excessively long initial and final setting times. This makes it difficult for them to accumulate near the entrance of the leakage zone, hindering rapid curing under flowing water conditions to seal the lost zone and resulting in significant losses of the plugging agent.

[0004] Polyurethane grouting materials, as a new type of high-molecular-weight fast-setting chemical grouting material, have a unique chemical reaction process. They can rapidly undergo cross-linking reactions upon contact with water, and their low viscosity and high fluidity allow them to easily penetrate small and deep cracks for filling and sealing leaks, quickly bonding and solidifying to rock walls or defect surfaces. They are widely used in mining for water filling and tunnel reinforcement. However, traditional polyurethane grouting materials have poor durability in water-containing environments, are easily dispersed by water flow, and are difficult to seal water inflows or jets. Furthermore, over time, the strength and toughness of the foam significantly decrease, leading to powdering, a marked weakening of water-stopping and reinforcement effects, and re-seepage in the later stages of construction. For example, invention patent application number CN108129630A discloses a method for preparing a solvent-free, single-component polyurethane grouting material. This method involves the reaction of hydrophilic polyether polyols with a number-average molecular weight of 8000–12000, using hydrophilic silicone oil instead of organic solvents as a diluent, resulting in a solvent-free, single-component polyurethane grouting material. Significant improvements have been made in the environmental friendliness of the materials, but further research is needed on the instantaneous water-blocking rate of the slurry and its durability in aquatic environments.

[0005] In addition, during drilling operations, it is necessary to inject plugging agents into the well using plugging tools to plug leaks. However, new solid-free plugging agents have the advantages of fast reaction and good plugging effect, but due to their fast reaction characteristics, they must not come into contact with water before reaching the leak point. Otherwise, the plugging agent will solidify (expand) before reaching the leak point, which will not only fail to achieve the purpose of plugging the leak, but may also cause the well to become blocked.

[0006] Therefore, there is an urgent need for a tool to prevent solid-free plugging agents from coming into premature contact with water before reaching the formation where plugging is needed, which would alter their chemical properties and affect the plugging effect on the formation. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a downhole tool for delivering a solid-phase plugging agent, thereby preventing the plugging agent from reacting prematurely with water in the drilling mud, causing blockage and wasting the plugging agent.

[0008] The second objective of this invention is to provide a targeted plugging construction process to achieve precision and economy in targeted plugging, thereby improving the success rate of plugging severe well leaks.

[0009] The third objective of this invention is to provide a solvent-free, single-component, nano-reinforced polyurethane grouting material to solve the problem that existing polyurethane grouting materials have poor durability in water-containing environments and are easily washed away by water flow.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A downhole tool for delivering a solid-free plugging agent includes a plugging packer and an agent delivery device. The agent delivery device includes an upper mechanism for the agent chamber, an agent chamber, and a lower mechanism for the agent chamber.

[0012] The agent dosing device includes a lower connector, an agent chamber connection connector, and a basket. The upper end of the lower connector is connected to the packer. An interceptor and a balance piston are respectively arranged from top to bottom in the lower connector body, and there is a gap between the interceptor and the balance piston. The lower end of the lower connector is connected to the upper end of the agent chamber connection connector, and the lower end of the agent chamber connection connector is connected to the agent chamber. The agent chamber has a cavity for storing the agent. The end of the agent chamber is connected to the basket. A release piston is arranged in the basket and is fixed to the basket by a release pin. A release hole is opened at the bottom of the basket, and the agent is released into the wellbore leakage layer through the release hole.

[0013] Furthermore, the interceptor is fixed to the lower connector body by a shear pin.

[0014] Furthermore, the lower connector body is provided with a through-hole in the radial direction, which is connected to the gap between the interceptor and the balance piston.

[0015] Furthermore, the body of the drug chamber connection connector is provided with an injection hole for injecting the drug, and an injection plug is connected to the injection hole; a drug piston floats above the drug liquid surface in the drug chamber.

[0016] Furthermore, the leak-sealing packer includes an upper connector, a central rod, and connecting components.

[0017] The central rod includes a ground central rod and a lower central rod spaced apart vertically. The upper end of the upper central rod is connected to an upper connector, and the lower end of the lower central rod is connected to a lower connector. The connecting assembly is located on the circumferential outer side of the central rod and seals the upper and lower central rods together. The connecting assembly includes an upper connecting assembly, a lower connecting assembly, and a rubber sleeve mechanism. The rubber sleeve mechanism is sleeved on the lower end of the upper central rod and can be compressed axially to generate radial expansion. The two ends of the rubber sleeve mechanism are respectively connected to the upper connecting assembly and the lower connecting assembly.

[0018] Furthermore, the upper connecting assembly includes a return spring, an escapement mechanism, and an upper outer cylinder. The upper end of the return spring is sleeved on the outer circle of the small end of the upper connector, and the lower end of the return spring abuts against the escapement mechanism. The escapement mechanism is sleeved on the upper center rod. The upper outer cylinder is sleeved outside the upper connector, the return spring, and the escapement mechanism, and the inner wall of the upper end of the upper outer cylinder is sealed to the outer wall of the lower end of the upper connector. The inner wall of the lower end of the upper outer cylinder is sealed to the rubber sleeve mechanism. / The outer circle of the small end of the upper rubber sleeve fixing block.

[0019] Furthermore, the rubber tube mechanism includes a slide tube, which is sleeved on the lower end of the upper center rod, and the upper end of the slide tube is connected to the escapement mechanism. The slide tube is fitted with an upper rubber tube fixing block, a rubber tube, and a lower rubber tube fixing block from top to bottom. The upper rubber tube fixing block is fixed to the slide tube by a suspension pin.

[0020] Furthermore, the escapement mechanism includes a pawl, a reset pawl, and a catcher. The pawl is fitted onto the upper center rod, the upper end of the pawl abuts against the reset spring, and the outer circle of the upper end face of the pawl is engaged with the inner diameter step of the upper outer cylinder. The reset pawl is connected to the middle of the upper center rod, and the catcher is fitted onto the reset pawl, with the lower end of the catcher connected to the slide cylinder.

[0021] Furthermore, the lower connecting assembly includes an upper piston, a ring plug, a lower piston, a middle outer cylinder, and a lower outer cylinder. The upper center rod and the lower center rod are connected by the upper piston. The ring plug and the lower piston are respectively sleeved on the lower center rod, and the lower end face of the ring plug abuts against the lower piston. The middle outer cylinder is sleeved outside the upper piston, and the upper inner wall of the middle outer cylinder is sealed around the lower outer wall of the rubber sleeve mechanism. The lower inner wall of the middle outer cylinder is sealed to the upper outer wall of the ring plug. The lower outer cylinder is sleeved outside the lower piston, and the upper inner wall of the lower outer cylinder is sealed around the lower outer wall of the ring plug.

[0022] Furthermore, a first thrust gap is formed between the lower end face of the rubber sleeve mechanism and the upper end face of the upper piston, and the lower end of the upper center rod has an upper center rod flow channel communicating with the first thrust gap; a second thrust gap is formed between the lower end face of the ring plug and the upper end face of the lower piston, and the middle part of the lower center rod has a lower center rod flow channel communicating with the second thrust gap.

[0023] Furthermore, the basket has a long bullet-shaped structure, and the top of the basket has a through hole that communicates with the inner cavity of the medicine chamber; the medicine chamber is composed of multiple hollow long tubes connected in series, and the length and number of hollow long tubes are determined by the dosage.

[0024] A targeted leak sealing construction process includes the following steps:

[0025] S1, calculate the amount of sealing agent used, and calculate the required number of chemical cavity roots based on the amount of sealing agent used;

[0026] S2, Insert tool for installation

[0027] Connect the lower mechanism of the chemical chamber, the chemical chamber, and the upper mechanism of the chemical chamber in sequence from bottom to top. After the connection is completed, inject a non-solid phase plugging agent into the chemical chamber. After the non-solid phase plugging agent is filled, seal it with the injection plug wire. Then connect the plugging packer to the lower connector, and connect the upper part of the plugging packer to the drill pipe.

[0028] S3, Leak sealing packer setting and leak sealing operation

[0029] After the drill string is lowered to the predetermined well depth for plugging, an aluminum alloy ball is dropped into the wellhead. Once the ball falls into the interceptor, the first pressurization causes the suspension pin to shear off. A second pressurization is then applied, causing the rubber sleeve to expand radially as it is compressed axially. The plugging packer then begins to set. During this process, the escape mechanism also moves, creating a self-locking mechanism that ensures a stable seal between the expanding rubber sleeve and the well wall. After the plugging packer is securely set, pressure is continuously increased, causing the shear pin to shear off. The balance piston and the chemical piston then move downwards, pushing the chemical chamber. With continued pressure increase, the release pin shears off, and the chemical piston pushes the solid-free plugging agent in the chemical chamber out of the basket's release hole into the wellbore leakage layer.

[0030] S4, after sealing the leak, pull out the drill.

[0031] After the plugging operation is completed, the drill pipe is pulled up, the escapement mechanism disengages and locks, the rubber sleeve self-restores its original shape, the plugging packer is released and the drill string is pulled out. After the drill string is pulled out to a safe section, a large-volume circulating mud test is used to verify whether the plugging was successful.

[0032] Furthermore, in step S4, when the drill string is pulled up and the tool for feeding the non-solid plugging agent is being fed in, the plugging packer is first disassembled, and then the upper structure of the agent chamber, the agent chamber, and the lower structure of the agent chamber are disassembled in sequence.

[0033] Furthermore, the solid-free sealing agent is a solvent-free, single-component, nano-reinforced polyurethane grouting material, prepared by the following method:

[0034] Step 1: 70-100 parts by weight of polyether polyol, 0-30 parts by weight of polyester polyol and 45-50 parts by weight of polyisocyanate are subjected to polymerization reaction to obtain polyurethane prepolymer.

[0035] Step 2: Mix the polyurethane prepolymer obtained in Step 1 with the catalyst, plasticizer, surfactant and nano-reinforcing agent to obtain solvent-free single-component nano-reinforced polyurethane grouting material.

[0036] Preferably, the preparation steps of the polyurethane prepolymer in step 1 are as follows: after vacuum dehydration and degassing of polyether polyol and polyester polyol at 60℃~100℃ for 2~3 hours, the temperature is then lowered to 48~52℃ and polyisocyanate is added to carry out polymerization reaction to obtain polyurethane prepolymer.

[0037] The polyether polyol is one or more of polyether diol, polyether triol, and polyether tetraol, preferably PPG polyether diol with a molecular weight of 200-4000 or polyether triol with a molecular weight of 300-3000 or a mixture thereof.

[0038] The polyester polyol is obtained by polymerizing phthalic anhydride with diol or triol, with a molecular weight of 200-2000 and a hydroxyl value of 200-400 mgKOH / g.

[0039] The preferred polyester polyol is a polycarbonate polyol with a molecular weight of 1500-2000 and a hydroxyl value of 60-120 mgKOH / g.

[0040] The isocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl polyisocyanate, or a mixture thereof.

[0041] The -NCO% content of the polyurethane prepolymer is 15% to 25%.

[0042] The catalyst is selected from one or more of aliphatic amines, alicyclic amines, aromatic amines, and alkanolamines and their ammonium salts, as well as organometallic catalysts such as dibutyltin dilaurate and stannous octoate. Further, the amount of the catalyst used is 1% to 5% of the mass of the polyurethane prepolymer.

[0043] The plasticizer is diethyl phthalate and / or dibutyl phthalate, and further, the amount of the plasticizer is 6% to 12% of the mass of the polyurethane prepolymer.

[0044] The surfactant is polyoxyethylene monolaurate, and further, the amount of the surfactant is 0.5% to 2% of the mass of the polyurethane prepolymer.

[0045] The toughening agent is L-lysine ethyl ester diisocyanate, and more preferably, the amount of the toughening agent is 1% to 5% of the mass of the polyurethane prepolymer.

[0046] The nano-reinforcing agent is nitrogen-doped carbon quantum dots synthesized by hydrothermal method. Furthermore, the amount of the nano-reinforcing agent is 0.3% to 1% of the mass of the polyurethane prepolymer.

[0047] A targeted leak sealing construction process includes the following steps:

[0048] (1) Polyether polyol, polyester polyol and organic polyisocyanate are polymerized to obtain polyurethane prepolymer;

[0049] (2) The polyurethane prepolymer obtained in step 1 is mixed with catalyst, plasticizer, surfactant and nano-reinforcing agent to obtain solvent-free single-component nano-reinforcing polyurethane grouting material.

[0050] (3) Determine the leakage area: Determine the leakage section based on factors such as downhole leakage, well depth, well inclination, and well diameter;

[0051] (4) Deploy special tools and grout: Use a plugging packer to seal the upper formation of the leakage area, load the solvent-free single-component nano-reinforced polyurethane grouting material prepared in the step into the agent chamber of the downhole plugging tool without solid phase plugging agent, quickly seal the agent chamber, connect the matching open hole plugging packer above, and send the agent dosing device containing the agent into the target formation downhole;

[0052] (5) Leakage plugging operation: Drop a ball from the wellhead, pressurize to 3MPa to open the plugging packer, set the annulus, continue pressurizing until the agent chamber is opened, and use the agent piston to squeeze the agent into the wellbore in one go. After the solvent-free single-component nano-reinforced polyurethane grouting material is injected into the leakage layer, under formation pressure, the polymerization rate is slow in the initial stage of the reaction. At this time, the grouting material (solvent-free single-component nano-reinforced polyurethane grouting material) still maintains an oily liquid state and can follow the flowing water to target the leakage location where the pressure suddenly decreases. At this time, the polymerization reaction intensifies, and the rapid foaming wraps the surrounding rock mass or fault wall. At the same time, the carbon dioxide generated can also enable the grout to advance into the depth of the leakage channel, achieving targeted leakage plugging.

[0053] By adopting the above technical solution, the present invention has the following beneficial effects:

[0054] 1. The downhole delivery tool for solid-free plugging agent provided by this invention has the functions of carrying the agent, sealing the leakage layer, and rapid injection, which improves the success rate of plugging large well leakage.

[0055] 2. The chemical chamber of the downhole plugging agent-free sealing tool is made of fiberglass tube and aluminum alloy. If the chemical agent takes effect and accidentally seals the tool, the packer can be removed and the chemical chamber can be drilled through. Therefore, the tool is drillable.

[0056] 3. The downhole delivery tool for solid-free plugging agent is modular, and its parts are 85% interchangeable with plugging packers, making maintenance and interchangeability convenient.

[0057] 4. The working method of the downhole delivery tool without solid plugging agent is pin shearing. The material and size are repeatedly checked to reduce errors and ensure opening pressure, resulting in high reliability.

[0058] 5. The expansion dimensions of the packer portion of the downhole delivery tool without solid plugging agent are: It can satisfy 8 1 / 8"~9 1 / 2" wellbore use.

[0059] 6. The escapement mechanism of the present invention comprises a pawl, a return pawl, and a catcher. When the upper connector moves downward, it pushes the pawl downward, and the barb at the end of the pawl inserts into the catcher. The catcher is constructed with reverse threads, and the barb at the end of the pawl embeds into the reverse threads of the catcher, thus forming a self-locking mechanism. When the upper connector is pulled, causing the upper center rod to move upward, it simultaneously moves the return pawl upward. The return pawl inserts into the common self-locking body of the pawl and the catcher. The return pawl has a wedge-shaped structure, which reduces the outer diameter of the pawl, causing the reverse teeth of the pawl to disengage from the annular thread of the catcher, thus releasing the self-lock. Therefore, the characteristic of this escapement mechanism is that the return pawl itself does not play a fixing role, but rather, during release, the cone-shaped portion of the return pawl causes radial deformation of the pawl, thereby separating the pawl from the catcher and achieving the release effect.

[0060] 7. The piston structure of the present invention adopts an internal sealing and external moving design. When the high-pressure mud pushes the piston, the piston moves and forms a liquid cavity between the central rod and the outer cylinder. The liquid cavity disappears again when the outer shell is reset during unsealing. This design ensures that the tool can be set multiple times downhole.

[0061] 8. After the single-component nano-reinforced polyurethane grouting material of the present invention is injected into the leakage layer, under the formation pressure, the polymerization rate is slow in the initial stage of the reaction. At this time, the polyurethane grouting material still maintains an oily liquid state and can follow the flowing water to target the leakage location where the pressure suddenly decreases. At this time, the polymerization reaction intensifies, and it quickly foams and wraps the surrounding rock mass or fault wall. At the same time, the carbon dioxide generated can also enable the grout to advance into the depth of the leakage channel, so as to achieve targeted plugging.

[0062] 9. The addition of L-lysine ethyl ester diisocyanate, which has both rate regulation and toughening properties, to the single-component nano-reinforced polyurethane grouting material system of the present invention can increase the dimensional stability of the foam, and the reaction rate can be adjusted by the end-group isocyanate; at the same time, the addition of nitrogen-doped carbon quantum dots with nano-size effect to the system can enhance the strength of the material while increasing the hydrophilicity of the interface, making the reaction faster and more uniform.

[0063] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0064] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other design solutions and drawings can be obtained based on these drawings without creative effort.

[0065] Figure 1 A schematic diagram of a downhole tool for delivering solid-phase plugging agent;

[0066] Figure 2 This is a schematic diagram of the packer structure;

[0067] Figure 3 This is a schematic diagram of the drug dosing device;

[0068] Figure 4 This is a schematic diagram of the pawl structure;

[0069] Figure 5 This is a schematic diagram of the reset claw structure;

[0070] Figure 6 This is a schematic diagram of the trap's structure;

[0071] Figure 7 The infrared spectrum of a solvent-free, single-component, nano-reinforced polyurethane grouting material.

[0072] Explanation of reference numerals in the attached figures:

[0073] 1. Upper connector; 2. Return spring; 3. Upper center rod; 4. Pawl; 5. Return pawl; 6. Snapper; 7. Upper rubber tube fixing block; 8. Rubber tube; 9. Upper center rod flow channel; 10. Upper piston; 11. Lower center rod; 12. Ring plug; 13. Lower center rod flow channel; 14. Lower piston; 15. Lower rubber tube fixing block; 16. Lower connector; 17. Interceptor; 18. Shear pin; 19. Breathing hole; 20. Balance piston; 21. Drug chamber connection connector; 22. Drug chamber; 23. Drug piston; 24. Basket; 25. Release piston; 26. Release hole; 27. Release pin; 28. Injection plug; 29. ​​Upper outer cylinder; 30. Middle outer cylinder; 31. Lower outer cylinder; 32. Slide cylinder; 33. Suspension pin.

[0074] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0075] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0076] Example 1:

[0077] This embodiment provides a downhole plugging agent-free delivery tool, including a packer and an agent dosing device connected to the lower end of the packer, such as... Figure 3 As shown, the agent dosing device includes an upper agent chamber mechanism, an agent chamber 22, and a lower agent chamber mechanism. The upper agent chamber mechanism includes a lower connector 16 and an agent chamber connecting connector 21. The upper end of the lower connector 16 is connected to a leak-sealing packer. An interceptor 17 and a balance piston 20 are respectively arranged from top to bottom in the body of the lower connector 16, and there is a gap between the interceptor 17 and the balance piston 20. The lower end of the lower connector is connected to the upper end of the agent chamber connecting connector 21. The lower end of the agent chamber connecting connector 21 is connected to the agent chamber 22. The agent chamber 22 has a cavity for storing the agent. The end of the agent chamber 22 is connected to the lower agent chamber mechanism. The lower agent chamber mechanism includes a basket 24 and a release piston 25 disposed in the basket 24. The release piston 25 is fixed to the basket 24 by a release pin 27. A release hole 26 is opened at the bottom of the basket 24, and the agent is released into the wellbore leakage layer from the release hole 26.

[0078] The working principle of this invention is as follows:

[0079] By throwing the ball and applying pressure, the packer pin is sheared, the rubber sleeve expands, and the packer is set. After the set is secure, the pressure is continuously increased until no solid plugging agent is fed into the tool. When the initial working pressure is reached, the balance piston and release piston move down to push the agent chamber. The pressure is continuously increased until the release pin is sheared. No solid plugging agent in the agent chamber is released from the release hole of the basket into the formation to complete the plugging.

[0080] Example 2:

[0081] Based on Example 1, such as Figure 1 , Figure 2As shown, the leak-sealing packer includes an upper connector 1, a central rod, and a connecting assembly. The central rod includes a ground central rod 3 and a lower central rod 11 spaced apart vertically. The upper end of the upper central rod 3 is connected to the upper connector 1, and the lower end of the lower central rod 11 is connected to the lower connector 16. The connecting assembly is located on the circumferential outer side of the central rod and seals the upper central rod 3 and the lower central rod 11 together. The connecting assembly includes an upper connecting component, a lower connecting component, and a rubber sleeve mechanism. The rubber sleeve mechanism is sleeved on the lower end of the upper central rod 3 and can be compressed axially to generate radial expansion. The two ends of the rubber sleeve mechanism are respectively connected to the upper connecting component and the lower connecting component.

[0082] Furthermore, the upper connecting assembly includes a return spring 2, an escapement mechanism, and an upper outer cylinder 29. The upper end of the return spring 2 is sleeved on the outer circle of the small end of the upper connector 1, and the lower end of the return spring 2 abuts against the escapement mechanism. The escapement mechanism is sleeved on the upper center rod 3. The upper outer cylinder 29 is sleeved on the outside of the upper connector 1, the return spring 2, and the escapement mechanism. The inner wall of the upper end of the upper outer cylinder 29 is sealed to the outer wall of the lower end of the upper connector 1, and the inner wall of the lower end of the upper outer cylinder 29 is sealed to the rubber sleeve mechanism (specifically, it is connected to the outer circle of the small end of the upper rubber sleeve fixing block 7).

[0083] Furthermore, the lower connecting assembly includes a piston assembly, and an inner and outer cylinder 30 and a lower outer cylinder 31 sleeved on the outside of the piston assembly. The piston assembly includes an upper piston 10, a ring plug 12, and a lower piston 14. The upper center rod 3 and the lower center rod 11 are connected through the upper piston 10. The ring plug 12 and the lower piston 14 are respectively sleeved on the lower center rod 11, and the lower end face of the ring plug 12 abuts against the lower piston 14. The upper inner wall of the inner cylinder 30 is sealed around the lower outer wall of the rubber sleeve mechanism, and the lower inner wall of the inner cylinder 30 is sealed to the upper outer wall of the ring plug 12. The upper inner wall of the lower outer cylinder 31 is sealed around the lower outer wall of the ring plug 12.

[0084] Furthermore, a first thrust gap is formed between the lower end face of the rubber sleeve mechanism and the upper end face of the upper piston 10, and the lower end of the upper central rod 3 has an upper central rod flow channel 9 communicating with the first thrust gap; a second thrust gap is formed between the lower end face of the ring plug 12 and the upper end face of the lower piston 14, and the middle part of the lower central rod 11 has a lower central rod flow channel 13 communicating with the second thrust gap. When drilling fluid enters the first thrust gap and the second thrust gap, the upper central rod 3 and the lower central rod 11 undergo axial displacement when the pressure increases, pushing the rubber sleeve to compress, converting the pressure into elastic potential energy to deform and expand the rubber sleeve, forming a set seal.

[0085] The piston assembly structure of the present invention adopts an internal sealing and external moving design. When the high-pressure mud pushes the piston, the piston moves and forms a liquid cavity between the central tube and the outer shell. The liquid cavity disappears again when the seal is broken because the outer shell resets.

[0086] When a loss occurs downhole, determine the depth of the loss, connect the solid-free plugging agent delivery tool, fill the agent chamber with solid-free plugging agent, and deliver it to about 30 meters above the loss layer. Drop an aluminum alloy ball and wait for about ten minutes until the ball falls to the ball holder (i.e., interceptor 17). Start the mud pump, and through mud pressure transmission, when the pump pressure reaches 4-5 MPa, the upper center rod 3 and lower center rod 11 are pushed down by the thrust of the upper and lower pistons, and the escapement mechanism is locked, and the rubber sleeve expands to seal the seal. Continue to pressurize to about 10 MPa to shear the ball holder pin (i.e., shear pin 18), push the balance piston and the agent piston, and continuously pressurize the agent chamber. When the pressure reaches about 15 MPa, the lower plug pin (i.e., release pin 27) is sheared, and the agent is pressed into the formation from the basket. After the sealing is completed, lift the tool, the escapement mechanism disengages and locks, the rubber sleeve returns to its original shape to release the seat seal, and the tool is pulled out of the drill bit. The leak sealing operation is now complete.

[0087] Example 3:

[0088] Based on the above embodiments, further, such as Figure 2 , Figure 4 , Figure 5 , Figure 6 As shown, the escapement mechanism includes a pawl 4, a return pawl 5, and a catcher 6. The pawl 4 is fitted onto the upper center rod 3, with its upper end abutting against the return spring 2. The outer circle of the upper end face of the pawl 4 is engaged with the inner diameter step of the upper outer cylinder 29. The return pawl 5 is connected to the middle of the upper center rod 3. The catcher 6 is fitted over the return pawl 5, with its lower end connected to the slide cylinder 32. The escapement mechanism consists of a pawl, a return pawl, and a catcher. When the upper connector moves downward, it pushes the pawl downward, and the barb at the end of the pawl inserts into the catcher. The catcher has a reverse thread, and the barb at the end of the pawl embeds into the reverse thread of the catcher, preventing it from retracting and forming a self-locking mechanism. When the upper connector is pulled, causing the upper center rod to move upward, it simultaneously moves the return pawl upward. The return pawl inserts into the common self-locking body of the pawl and the catcher. The return pawl has a wedge-shaped structure, which reduces the outer diameter of the pawl, causing the reverse teeth of the pawl to disengage from the annular thread of the catcher, thus releasing the self-locking mechanism.

[0089] Therefore, the characteristic of this escapement mechanism is that the reset pawl itself does not play a fixing role. Instead, during unlocking, the cone-shaped part of the reset pawl causes radial deformation of the pawl (reducing its outer diameter), thereby separating the pawl from the catcher and achieving the unlocking effect. Furthermore, this invention adds a reset spring to the upper part of the pawl to facilitate the reset of the rubber sleeve 8.

[0090] Example 4:

[0091] Based on Example 2, further, such as Figure 2As shown, the rubber sleeve mechanism includes a slide cylinder 32, which is sleeved on the lower end of the upper center rod 3, and the upper end of the slide cylinder 32 is connected to the escapement mechanism. The slide cylinder 32 is fitted with an upper rubber sleeve fixing block 7, a rubber sleeve 8, and a lower rubber sleeve fixing block 15 from top to bottom. The upper rubber sleeve fixing block 7 is fixed to the slide cylinder 32 by a suspension pin 33.

[0092] It should be noted that the rubber sleeve is made of rubber, so it can expand radially when compressed. The purpose of the suspension pin is to prevent the rubber sleeve from rubbing against the well wall when the packer is inserted into the well, causing it to expand prematurely and tear under friction, resulting in premature damage to the rubber sleeve.

[0093] When a loss of contact occurs downhole, determine the depth of the loss, calculate the amount of non-solid plugging agent needed, and calculate the required number of plugging chambers based on the amount of plugging agent. Connect the non-solid plugging agent delivery tool, fill it with the agent, and drop in an aluminum alloy ball. Once the ball reaches interceptor 17, start the mud pump. Through mud pressure transmission, when the pump pressure reaches 4-5 MPa, the upper and lower center rods move downwards under the thrust of the upper and lower pistons. The sliding cylinder and the two upper and lower rubber sleeve fixing blocks form a fixed whole nested on the upper center rod and do not move downwards with the upper center rod. The upper connector connected to the upper end of the upper center rod moves downwards, and the upper connector presses down on the upper outer cylinder. The lower end of the upper outer cylinder connects to the upper rubber sleeve fixing block, and at the same time, the lower upper rubber sleeve fixing block moves downwards, shearing off the suspension pin under external force. The upper rubber sleeve fixing block presses on the rubber sleeve, and because the rubber sleeve is made of rubber, its outer diameter expands under pressure. After the outer diameter of the rubber sleeve expands, it contacts the well wall, forming a seal.

[0094] Example 5:

[0095] Based on Example 1, such as Figure 1 , Figure 3 As shown, further, an interceptor 17 and a balance piston 20 are respectively arranged from top to bottom within the body of the lower connector 16, with a gap between the interceptor 17 and the balance piston 20. A through-hole 19 is provided radially on the body of the lower connector 16, and the through-hole 19 communicates with the gap. Because of the vent hole, drilling fluid flows into the drill pipe water hole, eliminating the need for additional grouting.

[0096] Furthermore, the interceptor 17 is fixed to the body of the lower connector 16 by a shear pin 18.

[0097] The main body of the drug chamber connection connector 21 is provided with an injection hole for injecting drugs, and an injection plug 28 is connected to the injection hole; a drug piston 23 floats above the drug liquid surface in the drug chamber 22, and the drug piston 23 in the drug chamber plays the role of sealing, transmitting pressure and pushing drugs.

[0098] Furthermore, the basket 24 has a long bullet-shaped structure, with a through hole at the top communicating with the inner cavity of the agent chamber 22, and radial through holes along the sidewalls of the basket 24. The basket is the agent release unit, and its bottom release hole is crucial for the rapid pressure penetration of the non-solid phase plugging agent into the leak layer.

[0099] It should be further explained that the drug chamber 22 is composed of multiple hollow long tubes connected in series, and the length and number of the hollow long tubes are determined by the dosage. Specifically, the hollow long tubes are glass fiber tubes made by winding untwisted glass fiber roving with anhydride-cured epoxy, and the circumferential elastic modulus of the glass fiber tubes is 3.5 x 10⁻⁶. 6 psi; Axial elastic modulus: 2.5 x 10⁻⁶ 6 psi; density: 126.9 lbs / ft 3 The specific gravity is 2.033, which meets the requirements of the preliminary calculation.

[0100] Example 6:

[0101] This invention provides a targeted leak sealing construction process, comprising the following steps:

[0102] S1, calculate the amount of sealing agent used, and calculate the required number of chemical cavity roots based on the amount of sealing agent used;

[0103] S2, Insert tool for installation

[0104] Connect the lower mechanism of the chemical chamber, the chemical chamber and the upper mechanism of the chemical chamber in order from bottom to top. After the connection is completed, inject a non-solid phase plugging agent into the chemical chamber. After the non-solid phase plugging agent is filled, seal it with the injection plug wire. Then connect the plugging packer to the lower connector 16 and connect the upper part of the plugging packer to the drill rod.

[0105] S3, Leak sealing packer setting and leak sealing operation

[0106] After the drill string is lowered to the predetermined well depth for plugging, an aluminum alloy ball is dropped into the wellhead. Once the ball falls into the interceptor 17, the first pressurization causes the suspension pin 33 to shear off. Then, a second pressurization is applied, and the rubber sleeve 8 is compressed axially and expands radially, causing the plugging packer to set. During this process, the escape mechanism also moves, forming a self-locking mechanism, which ensures a stable seal between the rubber sleeve 8 and the well wall. After the plugging packer is securely set, the pressure continues to increase, causing the shear pin 18 to shear off. The balance piston 20 and the chemical piston 23 move down to push the chemical chamber 22. With continued pressure increase, the release pin 27 shears off, and the chemical piston 23 pushes the solid-free plugging agent in the chemical chamber out of the release hole of the basket 24 into the wellbore leakage layer.

[0107] S4, after sealing the leak, pull out the drill.

[0108] (1) After the plugging operation is completed, the drill pipe is lifted, the escapement mechanism is disengaged and locked, and the rubber sleeve 8 returns to its original shape due to its own elasticity. After the plugging packer is unsealed, the drill is pulled out. After the drill is pulled out to a safe well section, the leakage is tested by a large-volume circulating mud to verify whether the plugging was successful.

[0109] (2) If the plugging tool is fixed in the well, first lift the drill string (more than 10 tons above the original suspended weight), rotate it clockwise for at least 2 minutes to disengage the left-hand thread of the lifting joint from the conversion joint, leave the drillable fiberglass pipe material structure in the well, and then lift the drill string out.

[0110] After the tool is lowered to the predetermined position, a ball is dropped into the wellhead. The ball enters the ball seat, and the first pressurization causes the fixing pin to shear off. Then, a second pressurization is applied, and the mud inside the pipe enters the piston chamber. The two-stage piston is displaced, pushing the rubber sleeve to deform and expand, forming a seat. During this process, the escape mechanism also moves. The pawl inside the mechanism is fixed to the catcher, keeping the seated rubber sleeve deformed. This ensures that the seal can be formed even during atmospheric pressure grouting.

[0111] When the seal is lifted, the resetting pawl of the locking mechanism reduces the outer diameter of the pawl, causing the pawl to disengage from the catcher. At this point, the rubber tube returns to its original shape due to its own elasticity, and the seat seal is released.

[0112] Example 7:

[0113] This embodiment provides a downhole insertion tool for solid-free plugging agents, including an upper connector 1, a return spring 2, an upper center rod 3, a pawl 4, a return pawl 5, a catcher 6, an upper rubber sleeve fixing block 7, a lower rubber sleeve fixing block 8, an upper piston 10, a lower center rod 11, an annular plug 12, a lower piston 14, a rubber sleeve 15, a lower connector 16, an interceptor 17, a balance piston 20, a chemical chamber connection connector 21, a chemical chamber 22, a chemical piston 23, a basket 24, a release piston 25, an upper outer cylinder 29, a middle outer cylinder 30, a lower outer cylinder 31, and a sliding cylinder 32. The lower end of the upper connector 1 is threaded. At the upper end of the upper center rod 3, the return spring 2 is sleeved on the outer circle of the lower end of the upper connector 1. The lower end of the return spring 2 rests on the end face of the pawl 4, which is sleeved on the upper center rod 3. The outer circle of the end face of the pawl 4 is engaged with the inner diameter step of the upper outer cylinder 29. The return pawl 5 is threadedly connected to the thread in the middle of the upper center rod 3. The catcher 6 is sleeved on the outside of the return pawl 5. The lower end of the catcher 6 is threadedly fixed to one end of the slide cylinder 32. The upper rubber tube fixing block 7, the rubber tube 8, and the lower rubber tube fixing block 15 are sequentially sleeved on the slide cylinder 32 from top to bottom. The suspension pin 33 passes through the upper rubber tube fixing block 7 and is fixed on the slide cylinder 32. The upper outer cylinder 29 is sleeved on the outside of the upper connector 1, the return spring 2, the pawl 4, and the catcher 6. The lower end of the upper outer cylinder 29 is threadedly connected to the outer circle of the small end of the upper rubber tube fixing block 7.

[0114] Furthermore, the upper center rod 3 and the lower center rod 44 are respectively connected to the upper piston 10 by threads. The ring plug 12 is sleeved on the lower center rod, and the lower end face of the ring plug 12 abuts against the lower piston 14. The lower end of the upper center rod 3 has a small hole as the upper center rod flow channel 9, which is located between the lower end face of the lower rubber sleeve fixing block 15 and the upper end face of the upper piston 10, and communicates with the first thrust gap formed between the lower end face of the lower rubber sleeve fixing block 15 and the upper end face of the upper piston 10. The middle part of the lower center rod 11 has a small hole as the lower center rod flow channel 13, which is located between the lower end face of the ring plug 12 and the upper end face of the lower piston 14, and communicates with the second thrust gap formed between the two.

[0115] The lower piston 14 is threadedly connected to the lower center rod 11. The lower outer cylinder 31 is sleeved around the ring plug 12 and the lower piston 14, and the upper inner wall of the lower outer cylinder 31 is threadedly connected to the lower outer wall of the ring plug 12; the lower center rod 11 is threaded at the end and threadedly connected to the lower connector 16.

[0116] An interceptor 17 and a balance piston 20 are respectively arranged from top to bottom inside the water eye of the lower connector 16. There is a gap between the interceptor 17 and the balance piston 20. There is a small hole in the lower connector 16 body that penetrates the lower connector body in the radial direction, which is a breather hole 19. The breather hole 19 is connected to the gap.

[0117] Furthermore, the interceptor 17 is fixed to the lower connector body 16 by a shear pin 18, and the balance piston 20 is positioned upwards from the reducing step inside the water inlet of the lower connector 16. The lower connector 16 is threadedly connected to the drug chamber connection connector 21, which has an injection hole on its body, sealed by an injection plug 28. The lower end of the drug chamber connection connector 21 is threadedly connected to the drug chamber 22, which is a hollow long tube. The length or number of hollow long tubes in the drug chamber can be adjusted according to the actual drug dosage. The end of the drug chamber 22 is threadedly connected to a basket 24, which contains a release piston 25. The release piston 25 is fixed to the basket 24 by a release pin 27. The release piston acts as a bottom blind plate, forming a cavity inside the drug chamber containing the drug. A drug piston 23 floats above the drug liquid surface.

[0118] It should be noted that the lower connector 16, interceptor 17, balance piston 20, agent chamber connection connector 21, agent chamber 22, basket 24, and release piston 25 are all made of drillable aluminum alloy. The suspension pin 33, shear pin 18, release pin 27, and injection plug 28 are made of brass; the rubber sleeve 8 and agent piston 23 are made of rubber, and other parts are made of steel. The thread between the lower center rod 11 and the lower connector 16 is a left-hand thread, while other connecting threads are conventional connections.

[0119] The working process of this solid-free plugging tool is as follows:

[0120] 1. Preparations before leak sealing

[0121] (1) Based on factors such as downhole leakage, well depth, well inclination, and well diameter, determine the leakage section, calculate the required plugging dose, the depth of the drill pipe, and the depth of the packer to be set and sealed.

[0122] (2) Check the equipment to ensure that the drilling rig's air circuit, oil circuit, and pipelines are unobstructed and that the mud pump is well supplied with water;

[0123] (3) During the grouting process, measure the number of pump strokes and the pumping time, and accurately calculate the injection volume.

[0124] 2. Insert the tool for connection and installation, and inject the non-solid phase sealant into the chemical chamber.

[0125] Before lowering the tool, first assemble the basket 24, release piston 25, and release pin 27 to form the bottom mechanism of the medicine chamber; then assemble the lower connector 16, interceptor 17, balance piston 20, medicine chamber connecting connector 21, and shear pin 18 to form the upper structure of the medicine chamber. The upper connector 1, return spring 2, upper center rod 3, pawl 4, return pawl 5, catcher 6, upper rubber tube fixing block 7, rubber tube 8, lower rubber tube fixing block 15, upper piston 10, lower center rod 11, ring plug 12, lower piston 14, suspension pin 33, upper outer cylinder 29, middle outer cylinder 30, lower outer cylinder 31, and slide cylinder 32 to form the sealing mechanism.

[0126] Upon discovery of a lost circulation zone downhole, the depth of the loss and the required dosage of reagent are calculated, and the number of reagent chambers needed is determined based on the dosage. Initially, the bottom mechanism of the reagent chamber is connected to the reagent chamber at the wellhead (the number of connections matches the calculated number of reagent chambers). After the reagent chamber connection is complete, the upper structure of the reagent chamber is connected. After the reagent dosing device is assembled, reagent is injected through the injection hole on the reagent chamber connector 21. Once the reagent is full, it is sealed by the injection plug 28. Then, the packer mechanism is connected, noting that the packer mechanism and the lower connector require a counter-clockwise screw thread. The upper part of the packer mechanism is connected to the drill pipe. The number of drill pipes is adjusted according to the depth of the lost circulation zone, ultimately requiring the packer mechanism to be positioned approximately 10 meters above the lost circulation zone at the bottom of the well. It is worth mentioning that during the drill pipe connection process, because the lower connector has a breather hole, drilling fluid flows into the drill pipe's water hole, eliminating the need for additional grouting.

[0127] 3. Sealing and feeding operations

[0128] After reaching the target formation, an aluminum ball is dropped into the water hole of the drill pipe at the wellhead. Depending on the actual depth, the ball is allowed to fall into the interceptor 17. Since the inner diameter of the interceptor 17 is smaller than the diameter of the aluminum ball, the ball remains stuck within the interceptor 17. The drill pipe is then connected to a mud pump, which is started to pressurize the drilling fluid. The pressure increases due to the pressure buildup caused by the aluminum ball.

[0129] a. High-pressure drilling fluid flows through the upper center rod channel 9 into the gap between the lower rubber sleeve fixing block 15 and the upper piston 10. The lower rubber sleeve fixing block 15 and the upper piston 10 are nested on the upper center rod 3 and are relatively sealed to form a cavity. As the drilling fluid pressure increases, the drilling fluid pushes the upper piston 10 downward within the cavity. The upper piston 10 is rigidly connected to the upper center rod 3, pulling the upper center rod 3 downward.

[0130] b. High-pressure drilling fluid flows through the lower center rod channel 13 into the gap between the ring plug 12 and the lower piston 14. The ring plug 12 and the lower piston 14 are nested on the lower center rod 11 and are relatively sealed to form a cavity. As the drilling fluid pressure increases, the drilling fluid pushes the lower piston 14 downward within the cavity. The lower piston 14 is rigidly connected to the lower center rod 11, pulling the lower center rod 11 downward. The lower center rod 11 and the upper center rod 3 are rigidly connected to the upper piston 10, simultaneously pulling the upper center rod 3 downward.

[0131] After the upper center rod 3 moves downward under the combined action of the upper piston 10 and the lower piston 14, the sliding cylinder 32, together with the upper and lower rubber cylinder fixing blocks and the rubber cylinder 8, forms a fixed whole nested on the upper center rod 3 and does not move downward with the upper center rod 3. The upper end of the upper center rod 3 is connected to the upper connector 1, which moves downward. The upper connector 1 presses down on the upper outer cylinder 29. The lower end of the upper outer cylinder 29 is connected to the upper rubber cylinder fixing block 7, and at the same time, it pushes the upper rubber cylinder fixing block 7 downward, shearing off the suspension pin 33 under the action of external force (the shearing pressure of the suspension pin is 2-3 MPa). The upper rubber cylinder fixing block 7 presses on the rubber cylinder 8. Since the rubber cylinder 8 is made of rubber, its outer diameter expands under pressure. After the outer diameter of the rubber cylinder 8 expands, it contacts the well wall, forming a seal and preventing communication between the upper and lower well sections. Simultaneously, the upper connector 1 pushes the pawl 4 downwards, and the barb at the end of the pawl 4 inserts into the catcher 6. The catcher 6 is made of reverse threads. The barb at the end of the pawl 4 embeds into the reverse threads of the catcher 6 and does not retract, forming a self-locking mechanism. This causes the rubber sleeve to expand and form a stable seal with the well wall. This process requires waiting 10 minutes (maintaining pressure of 7-8 MPa, without increasing the pressure) before proceeding to the next step.

[0132] After the sealing components are securely sealed, the mud pump continues to pressurize the system. Under pressure, the aluminum ball continuously applies a downward force to the interceptor 17, thereby shearing off the shear pin 18 (the rated pressure of the shear pin is 10-11 MPa). The aluminum ball and the interceptor move downwards synchronously, and the ground pressure gauge shows a sudden drop in pressure. The aluminum ball and the interceptor fall onto the balance piston 20, which continues to pressurize it. Due to the combined action of the release pin 27 at the bottom of the agent chamber and the release piston 20, the agent chamber forms a sealed space. Therefore, the aluminum ball, the interceptor, the balance piston 20, and the agent piston 23 jointly pressurize the agent chamber, and the ground pressure gauge shows a sudden rise in pressure after a drop. The release pin 27 is set to a pressure of 15 MPa. When the pressure is continuously increased to above 15 MPa, the release pin 27 is sheared off. The release pin 27 and the release piston 25 move downwards together, and the agent in the chemical chamber moves downwards under pressure into the basket 24, where it is ejected from the release hole 26. The surface pressure gauge reading drops instantaneously (approximately 1-3 MPa, varying slightly depending on well depth), confirming that the agent has been released into the wellbore. At this point, the pump stops, and a timer is started. The time required to remove the agent from the tubing is calculated based on the mud pump's displacement. The pump is stopped when the specified time is reached. At this point, the aluminum ball, interceptor 17, balance piston 20, chemical piston 23, and release piston 25 have all fallen into the basket 24, and the agent in the chemical chamber has been replaced with drilling fluid. The plugging operation is complete.

[0133] 4. Drilling resumes after leak sealing is complete.

[0134] After the plugging operation is completed, the drill pipe is lifted, and the pulling force is transmitted to the solid-free plugging agent delivery tool. The upper connector 1 is pulled, causing the upper center rod 3 to move upward, which in turn causes the reset claw 5 to move upward. The reset claw 5 inserts into the common self-locking body of the pawl 4 and the catcher 6. The reset claw 5 has a wedge-shaped structure, which reduces the outer diameter of the pawl 4, and the reverse teeth of the pawl 4 disengage from the annular thread of the catcher 6, releasing the self-locking mechanism. Because the rubber sleeve 8 is made of rubber, it has self-resetting properties, and the sleeve slowly returns to its original size. The packer mechanism is then unsealed, a process that takes about 5 minutes. After unsealing, the drill string is quickly pulled out to prevent the agent from solidifying and fixing the tool downhole. When lifting to the solid-free plugging agent delivery tool, the plugging packer is disassembled first, followed by the upper structure of the agent chamber, the agent chamber itself, and the lower structure of the agent chamber, until the operation is completed.

[0135] During tripping, the non-solid plugging agent is solidified inside the wellbore. After the packer is released, the drill string is rotated clockwise. The thread between the lower center rod 3 and the lower connector 16 is a left-hand thread, which disengages when rotated clockwise. Tripping continues; after the packer is retrieved from the wellhead, the drill bit is lowered to continue drilling. Because the upper, lower, and upper structures of the chemical chamber are made of drillable materials such as aluminum alloy, rubber, and copper, drilling continues after reaching the target formation.

[0136] Example 8:

[0137] This embodiment discloses that the solid-free sealing agent used in this invention is a solvent-free, single-component, nano-reinforced polyurethane grouting material, prepared by the following method:

[0138] Step 1: 70-100 parts by weight of polyether polyol, 0-30 parts by weight of polyester polyol and 45-50 parts by weight of polyisocyanate are subjected to polymerization reaction to obtain polyurethane prepolymer.

[0139] Step 2: Mix the polyurethane prepolymer obtained in Step 1 with the catalyst, plasticizer, surfactant, toughening agent and nano-reinforcing agent to obtain a solvent-free single-component nano-reinforced polyurethane grouting material.

[0140] Furthermore, the present invention does not limit the number of hydroxyl groups in the polyether polyol, which can be one or more of polyether diol, polyether triol, and polyether tetraol, preferably PPG polyether diol with a molecular weight of 200-4000 or polyether triol with a molecular weight of 300-3000 or a mixture thereof. The polyether polyol can be any commercially available specification, preferably PPG200-PPG4000 produced by Haian Petrochemical Plant in Jiangsu Province.

[0141] The polyester polyol is obtained by polymerizing phthalic anhydride with diol or triol, with a molecular weight of 200-2000 and a hydroxyl value of 200-400 mgKOH / g.

[0142] The polyester polyol or preferably a polycarbonate polyol with a molecular weight of 1500-2000 has a hydroxyl value of 60-120 mgKOH / g.

[0143] The isocyanate is selected from one or more of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and polymethylene polyphenyl polyisocyanate (PAPI), or a mixture thereof.

[0144] The -NCO% content of the polyurethane prepolymer, which is 15% to 25%, refers to the percentage of isocyanate groups by mass relative to the total mass of the polyurethane prepolymer. The toluene diisocyanate (TDI) can be any commercially available TDI of various specifications, preferably TDI-80 produced by Yantai Wanhua Polyurethane Co., Ltd. The diphenylmethane diisocyanate (MDI) can be any commercially available MDI of various specifications, preferably MDI-50 produced by Yantai Wanhua Polyurethane Co., Ltd. Specifically, the preparation steps of the polyurethane prepolymer in step 1 are as follows: After vacuum dehydration and degassing of polyether polyol and polyester polyol at 60℃ to 100℃ for 2 to 3 hours, the temperature is then lowered to 48 to 52℃, and polyisocyanate is added to carry out a polymerization reaction to obtain the polyurethane prepolymer. Its infrared spectrum is shown in the appendix. Figure 7 .

[0145] Furthermore, the catalyst is selected from one or more of aliphatic amines, alicyclic amines, aromatic amines, and alkanolamines and their ammonium salts, as well as organometallic catalysts such as dibutyltin dilaurate and stannous octoate. Further, the amount of the catalyst is preferably 1% to 5% of the mass of the polyurethane prepolymer.

[0146] Furthermore, the plasticizer is diethyl phthalate and / or dibutyl phthalate, and the amount of the plasticizer is preferably 6% to 12% of the mass of the polyurethane prepolymer; the plasticizer used has good compatibility with polyurethane, and significant stability and synergistic effect.

[0147] The surfactant is polyoxyethylene monolaurate, and more preferably, the amount of the surfactant is 0.5% to 2% of the mass of the polyurethane prepolymer.

[0148] The nano-reinforcing agent is nitrogen-doped carbon quantum dots synthesized via a hydrothermal method. These nitrogen-doped carbon quantum dots impart excellent interfacial properties and uniformity in water reaction to the solvent-free, single-component nano-reinforced polyurethane grouting material, thereby enhancing the compressive strength and dimensional stability of the foam. Furthermore, the amount of the nano-reinforcing agent is preferably 0.3% to 1% of the mass of the polyurethane prepolymer.

[0149] The toughening agent is L-lysine ethyl ester diisocyanate, which can generate elastic polyurethane in situ upon contact with water, increasing the dimensional stability of the foam. The end group is isocyanate, which can be used to adjust the reaction rate upon contact with water. The amount of the toughening agent is preferably 1% to 5% of the mass of the polyurethane prepolymer.

[0150] This invention discloses a solvent-free, single-component, nano-reinforced polyurethane grouting material with excellent water-dispersion resistance. During construction, it is delivered into the leakage area using a specialized downhole tool for solid-free plugging agents. Upon contact with water, it rapidly foams, generating carbon dioxide to propel the grout deep into the leakage layer or into minute cracks in the rock mass. This enables targeted plugging of seepage prevention systems with long water-seepage paths and hidden, invisible defects. The system incorporates L-lysine ethyl ester diisocyanate, which combines rate regulation and toughening, increasing the dimensional stability of the foam. The reaction rate can be adjusted using end-group isocyanates. Simultaneously, nitrogen-doped carbon quantum dots with nano-size effects are added to the system, enhancing material strength while improving interfacial hydrophilicity, resulting in a faster and more uniform reaction. The accompanying solid-free downhole delivery tool achieves precise and economical targeted plugging.

[0151] Example 9:

[0152] This embodiment provides a targeted leak sealing construction process, including the following steps:

[0153] 1. Polyether polyol, polyester polyol and organic polyisocyanate are polymerized to obtain polyurethane prepolymer;

[0154] 2. The polyurethane prepolymer obtained in step 1 is mixed with catalyst, plasticizer, surfactant and nano-reinforcing agent to obtain solvent-free single-component nano-reinforced polyurethane grouting material.

[0155] 3. Determine the leakage area: Based on factors such as downhole leakage, well depth, well inclination, and well diameter, determine the leakage zone section;

[0156] 4. Set up special tools and grout: Use a plugging packer to seal the upper formation of the leakage area, load the solvent-free single-component nano-reinforced polyurethane grouting material prepared in step 2 into the agent chamber of the downhole plugging tool without solid phase plugging agent, quickly seal the agent chamber, connect the matching open hole plugging packer above, and send the agent dosing device containing the agent into the target formation downhole.

[0157] 5. Leakage Plugging Operation: Drop a ball from the wellhead, pressurize to 3MPa to open the plugging packer, set the annulus, continue pressurizing until the chemical chamber is opened, and use the chemical piston to squeeze the chemical into the wellbore in one go. After the solvent-free single-component nano-reinforced polyurethane grouting material is injected into the leaking layer, under formation pressure, the polymerization rate is slow in the initial stage of the reaction. At this time, the grouting material still remains in an oily liquid state and can follow the flowing water to target the leakage location where the pressure suddenly decreases. At this time, the polymerization reaction intensifies, and the grouting material quickly foams and wraps around the surrounding rock mass or fault wall. At the same time, the carbon dioxide generated can also enable the grout to advance into the depth of the leakage channel, achieving targeted leakage plugging.

[0158] Example 10:

[0159] This embodiment provides a solvent-free, single-component, nano-reinforced polyurethane grouting material, prepared by the following method:

[0160] 1) Add 100g of PPG polyether diol to a reactor, heat to 100℃, stir, dehydrate and degas under vacuum for 3 hours, cool to 50℃, then add 45g of toluene diisocyanate TDI-80, and polymerize at a reaction temperature of 80℃ for 3 hours to obtain 145g of polyurethane prepolymer; wherein, the number average molecular weight of the polyether diol is 3000; the -NCO content of the polyurethane prepolymer is 16.26%;

[0161] 2) Cool down to 40℃, and thoroughly mix the polyurethane prepolymer obtained in step 1) with 2.9g polyoxyethylene monolaurate, 2.9g L-lysine ethyl ester diisocyanate, 0.8g ethylenediamine, 2g dibutyltin dilaurate, 15g diethyl phthalate and 1g nitrogen-doped carbon quantum dots to obtain solvent-free single-component nano-reinforced polyurethane grouting material.

[0162] Example 11:

[0163] This embodiment provides a solvent-free, single-component, nano-reinforced polyurethane grouting material, prepared by the following method:

[0164] 1) Add 100g of PPG polyether triol to a reactor, heat to 80℃, stir, dehydrate and degas under vacuum for 3 hours, cool to 50℃, then add 100g of diphenylmethane diisocyanate MDI-50, and polymerize at a reaction temperature of 82℃ for 3 hours to obtain 200g of polyurethane prepolymer; wherein, the number average molecular weight of the polyether triol is 4000; the -NCO content of the polyurethane prepolymer is 20.31%;

[0165] 2) Cool down to 40℃, and thoroughly mix the polyurethane prepolymer obtained in step 1) with 1.0g polyoxyethylene monolaurate, 2g L-lysine ethyl ester diisocyanate, 1g dibutyltin dilaurate, 1.0g triethanolamine, 15g dioctyl phthalate and 0.725g nitrogen-doped carbon quantum dots to obtain solvent-free single-component nano-reinforced polyurethane grouting material.

[0166] Example 12:

[0167] This embodiment provides a solvent-free, single-component, nano-reinforced polyurethane grouting material, prepared by the following method:

[0168] 1) Add 100g of hydrophilic aromatic polyester diol to a reactor, heat to 98℃, stir, dehydrate and degas under vacuum for 3 hours, cool to 48℃, then add 25g of toluene diisocyanate TDI-80 and 50g of diphenylmethane diisocyanate, and polymerize at a reaction temperature of 78℃ for 3 hours to obtain 175g of polyurethane prepolymer; wherein, the number average molecular weight of the aromatic polyester diol is 2000; the -NCO content of the polyurethane prepolymer is 18.36%;

[0169] 2) Cool down to 40℃, and thoroughly mix the polyurethane prepolymer obtained in step 1) with 1.75g ​​polyoxyethylene monolaurate, 5.25g L-lysine ethyl ester diisocyanate, 4g dibutyltin dilaurate, 1.0g diethylamine, 6g diethyl phthalate, 6g dioctyl phthalate, and 1.5g nitrogen-doped carbon quantum dots to obtain solvent-free single-component nano-reinforced polyurethane grouting material.

[0170] Example 13:

[0171] This embodiment provides a solvent-free, single-component, nano-reinforced polyurethane grouting material, prepared by the following method:

[0172] 1) Add 70g of PPG polyether diol and 30g of polycarbonate polyol to a reactor, heat to 98℃, stir, dehydrate and degas under vacuum for 3 hours, cool to 50℃, then add 50g of toluene diisocyanate TDI-80, and polymerize at 80℃ for 3 hours to obtain 150g of polyurethane prepolymer; wherein, the number average molecular weight of PPG polyether diol is 200, the number average molecular weight of polycarbonate polyol is 1500, and the -NCO content of polyurethane prepolymer is 18.53%;

[0173] 2) Cool down to 40℃, and thoroughly mix the polyurethane prepolymer obtained in step 1) with 3g of polyoxyethylene monolaurate, 4.5g of L-lysine ethyl ester diisocyanate, 2.5g of o-phenylenediamine, 5g of dibutyltin dilaurate, 1.5g of nitrogen-doped carbon quantum dots and 13g of diethyl phthalate to obtain solvent-free single-component nano-reinforced polyurethane grouting material.

[0174] Example 14:

[0175] This embodiment provides a solvent-free, single-component, nano-reinforced polyurethane grouting material, prepared by the following method:

[0176] 1) Add 80g of PPG polyether triol and 20g of aromatic polyester triol to a reactor, heat to 100℃, stir, dehydrate and degas under vacuum for 3 hours, cool to 50℃, then add 50g of toluene diisocyanate TDI-80, and polymerize at 80℃ for 3 hours to obtain 150g of polyurethane prepolymer; wherein, the number average molecular weight of the polyether triol is 600; the number average molecular weight of the aromatic polyester triol is 1000; and the -NCO content of the polyurethane prepolymer is 17.25%.

[0177] 2) Cool down to 40℃, and thoroughly mix the polyurethane prepolymer obtained in step 1) with 2.5g polyoxyethylene monolaurate, 7.5g L-lysine ethyl ester diisocyanate, 2.0g triethylenediamine, 5.5g stannous octoate, 1.0g nitrogen-doped carbon quantum dots and 13g diethyl phthalate to obtain solvent-free single-component nano-reinforced polyurethane grouting material.

[0178] In Examples 10-14, PPG polyether diol, PPG polyether triol, aromatic polyester diol, and hydrophilic polycarbonate polyol were all supplied by Haian Petrochemical Plant, with a functionality of 2-3 and a number-average molecular weight of 200-4000. Toluene diisocyanate TDI-80 and diphenylmethane diisocyanate MDI-80 were supplied by Yantai Wanhua Polyurethane Co., Ltd.

[0179] In the above embodiments, the reactions were all carried out in a glass reactor equipped with a stirrer, a thermocouple thermometer, and a calcium chloride drying tube.

[0180] At 25°C, the solvent-free single-component nano-reinforced polyurethane grouting materials of Examples 10-25 were mixed with water at a mass ratio of 100:5 and stirred for 5 seconds. The gel time, viscosity, water swelling rate and compressive strength of the sand and gravel consolidation were tested. The test method was performed in accordance with the People's Republic of China Building Materials Industry Standard JC / T2041-2010 "Polyurethane Grouting Materials". The test results are shown in Table 1 below.

[0181]

[0182] The system incorporates L-lysine ethyl ester diisocyanate, which has both rate-regulating and toughening properties. It is environmentally friendly and can generate elastic polyurethane in situ upon contact with water, increasing the dimensional stability of the foam. The end group is isocyanate, which can be used to regulate the reaction rate upon contact with water. Nitrogen-doped carbon quantum dots with nano-size effect are added to the system, which enhances the strength of the material while increasing the hydrophilicity of the interface, making the reaction faster and more uniform.

[0183] On-site targeted leak sealing implementation case

[0184] Example 15:

[0185] Well 416-11 in Team 30663 experienced three instances of loss of return during surface drilling to depths of 88 meters, 107 meters, and 138 meters. The drilling fluid density was 1.01 g / cm3 and the viscosity was 35S. Both bridge plug and cement slurry plugging methods were ineffective.

[0186] Using the solvent-free single-component nano-reinforced polyurethane grouting material from Example 12, combined with a downhole tool containing a solid-phase plugging agent, targeted plugging was performed, successfully sealing three large fractured leakage layers in one operation, with no recurrence afterward.

[0187] Construction steps: Load 500 kg of solvent-free single-component nano-reinforced polyurethane grouting material into the chemical chamber of the downhole tool → quickly seal the chemical chamber → connect the matching open-hole plugging packer above → send the tool containing the chemical to a position 87 meters downhole → drop a ball at the wellhead → pressurize to 3 MPa to open the packer → set the annulus → continue pressurizing to 5 MPa to open the chemical chamber → use the rubber plug inside the pipe to squeeze the chemical into the wellbore in one go → the polyurethane material expands and reacts rapidly upon contact with water → autonomously locates 3 fractured leakage zones downhole → wait continuously for 30 minutes → lift the drill string to 6 tons → release the packer → pull out the drill string and retrieve the tool → complete the targeted plugging operation, then run in the normal drilling assembly, sweep away the residual polyurethane reactants in the wellbore, resume drilling until the drilling is completed without any leakage.

[0188] Example 16:

[0189] Well H48-4, operated by Team 40649, reached a depth of 636 meters in the Luohe Formation during the second drilling phase. The circulating pump pressure dropped from 8 MPa to 3 MPa, resulting in loss of return and leakage. The drilling fluid density was 1.01 g / cm³. 3 With a viscosity of 34s, both bridge plug and cement slurry plugging methods were ineffective. Using the fast-setting, high-expansion polyurethane material from Example 4 of the invention, combined with a downhole tool containing no solids-phase plugging agent, targeted plugging was performed, successfully sealing the large fractured leakage layer in the Luohe Formation in one attempt, with no recurrence afterward.

[0190] Using the solvent-free single-component nano-reinforced polyurethane grouting material of Example 13, combined with a downhole tool containing a solid-phase plugging agent, targeted plugging was performed, successfully sealing three large fractured leakage layers in one operation, with no recurrence afterward.

[0191] Construction steps: 750kg of solvent-free single-component nano-reinforced polyurethane grouting material is loaded into the agent chamber of the downhole tool → the agent chamber is quickly sealed → a matching open-hole plugging packer is connected at the top → the tool containing the agent is sent down to a position of 632 meters downhole → a ball is dropped at the wellhead → pressure is applied to 4MPa to open the packer → annular setting → pressure is applied to 8MPa to open the agent chamber → the agent is squeezed into the wellbore in one go using the rubber stopper inside the pipe → the polyurethane material expands rapidly upon contact with water → it autonomously locates the downhole fracture layer → wait for 20 minutes → the drill string is lifted by 15 tons → the packer is released → the drill string is pulled out and the tool is retrieved → the targeted plugging operation is completed.

[0192] The normal drilling tool assembly was lowered in, the residual polyurethane reactants in the wellbore were swept away, and drilling resumed until the drilling was completed without any leakage.

[0193] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can devise many other modifications and implementations without departing from the technical principles of the present invention. These modifications and implementations will fall within the scope and spirit of the principles disclosed in this application. More specifically, within the scope of the disclosure, drawings, and claims of this application, various variations and improvements can be made to the components and / or layout of the subject matter combination layout. Besides the variations and improvements to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A downhole tool for delivering a solid-phase plugging agent, characterized in that: It includes a leak-sealing packer and a reagent dosing device, wherein the reagent dosing device includes an upper reagent chamber mechanism, a reagent chamber (22), and a lower reagent chamber mechanism. The upper mechanism of the drug chamber includes a lower connector (16) and a drug chamber connecting connector (21). The upper end of the lower connector (16) is connected to the leak-sealing packer. An interceptor (17) and a balance piston (20) are respectively arranged from top to bottom in the body of the lower connector (16), and there is a gap between them. At the same time, a through-hole (19) is provided on the body of the lower connector (16) along the radial direction. The through-hole (19) is connected to the gap between the interceptor (17) and the balance piston (20). The lower end of the lower connector is connected to the upper end of the drug chamber connection connector (21), and the lower end of the drug chamber connection connector (21) is connected to the drug chamber (22). The drug chamber (22) has a cavity for storing the drug. The drug chamber (22) is composed of multiple hollow long tubes connected in series. The length and number of hollow long tubes are determined according to the required drug dosage. Specifically, the hollow long tubes are glass fiber tubes with a circumferential elastic modulus of 3.5 × 10⁻⁶. 6 psi, axial elastic modulus is 2.5×10 6 psi, density 126.91bs / ft 3 The glass fiber tube has a specific gravity of 2.033 and is made of glass fiber roving wound with acid anhydride-cured epoxy. The end of the drug chamber (22) is connected to the lower part of the drug chamber mechanism, which includes a basket (24) and a release piston (25) disposed in the basket (24). The release piston (25) is fixed to the basket (24) by a release pin (27). The bottom of the basket (24) is provided with a release hole (26), and the drug is released from the release hole (26) into the wellbore leakage layer. In addition, the main body of the drug chamber connecting joint (21) is provided with an injection hole for injecting the drug, and an injection plug wire (28) is connected to the injection hole. A drug piston (23) floats above the drug liquid surface in the drug chamber (22). The interceptor (17) is fixed to the body of the lower connector (16) by a shear pin (18).

2. The downhole delivery tool for solid-free plugging agent as described in claim 1, characterized in that: The leak-sealing packer includes an upper connector (1), a central rod, and connecting components. The central rod includes a ground central rod (3) and a lower central rod (11) spaced apart vertically. The upper end of the upper central rod (3) is connected to an upper connector (1), and the lower end of the lower central rod (11) is connected to a lower connector (16). The connecting assembly is located on the circumferential outer side of the central rod and seals the upper central rod (3) and the lower central rod (11) together. The connecting assembly includes an upper connecting assembly, a lower connecting assembly, and a rubber sleeve mechanism. The rubber sleeve mechanism is sleeved on the lower end of the upper central rod (3) and can be compressed axially to generate radial expansion. The two ends of the rubber sleeve mechanism are respectively connected to the upper connecting assembly and the lower connecting assembly.

3. The downhole delivery tool for solid-free plugging agent as described in claim 2, characterized in that: The upper connecting assembly includes a return spring (2), an escapement mechanism, and an upper outer cylinder (29). The upper end of the return spring (2) is sleeved on the outer circle of the small end of the upper connector (1), and the lower end of the return spring (2) abuts against the escapement mechanism. The escapement mechanism is sleeved on the upper center rod (3). The upper outer cylinder (29) is sleeved on the outside of the upper connector (1), the return spring (2), and the escapement mechanism. The inner wall of the upper end of the upper outer cylinder (29) is sealed to the outer wall of the lower end of the upper connector (1), and the inner wall of the lower end of the upper outer cylinder (29) is sealed to the rubber sleeve mechanism.

4. The downhole delivery tool for solid-free plugging agent as described in claim 3, characterized in that: The rubber tube mechanism includes a slide tube (32), which is sleeved on the lower end of the upper center rod (3), and the upper end of the slide tube (32) is connected to the escapement mechanism. The slide tube (32) is sleeved with an upper rubber tube fixing block (7), a rubber tube (8), and a lower rubber tube fixing block (15) from top to bottom. The upper rubber tube fixing block (7) is fixed on the slide tube (32) by a hanging pin (33).

5. The downhole delivery tool for solid-free plugging agent as described in claim 4, characterized in that: The escapement mechanism includes a pawl (4), a reset pawl (5), and a catcher (6). The pawl (4) is fitted onto the upper center rod (3), and the upper end of the pawl (4) abuts against the reset spring (2). The outer circle of the upper end face of the pawl (4) is engaged on the inner diameter step of the upper outer cylinder (29). The reset pawl (5) is connected to the middle of the upper center rod (3). The catcher (6) is fitted onto the reset pawl (5), and the lower end of the catcher (6) is connected to the slide cylinder (32).

6. The downhole delivery tool for solid-free plugging agent as described in claim 4, characterized in that: The lower connecting assembly includes a piston assembly and an inner and outer cylinder (30) and a lower outer cylinder (31) sleeved on the outside of the piston assembly. The piston assembly includes an upper piston (10), a ring plug (12), and a lower piston (14). The upper center rod (3) and the lower center rod (11) are connected by the upper piston (10). The ring plug (12) and the lower piston (14) are respectively sleeved on the lower center rod (11), and the lower end face of the ring plug (12) abuts against the lower piston (14). The upper inner wall of the inner cylinder (30) is sealed around the lower outer wall of the rubber sleeve mechanism, and the lower inner wall of the inner cylinder (30) is sealed to the upper outer wall of the ring plug (12). The upper inner wall of the lower outer cylinder (31) is sealed around the lower outer wall of the ring plug (12).

7. The downhole delivery tool for solid-free plugging agent as described in claim 6, characterized in that: A first thrust gap is formed between the lower end face of the rubber sleeve mechanism and the upper end face of the upper piston (10), and the lower end of the upper center rod (3) has an upper center rod flow channel (9) that communicates with the first thrust gap; a second thrust gap is formed between the lower end face of the ring plug (12) and the upper end face of the lower piston (14), and the middle part of the lower center rod (11) has a lower center rod flow channel (13) that communicates with the second thrust gap.

8. The downhole delivery tool for solid-free plugging agent as described in claim 1, characterized in that: The basket (24) has a long bullet-shaped structure, and the top of the basket (24) has a through hole that communicates with the inner cavity of the medicine chamber (22).

9. A targeted plugging construction process using a downhole delivery tool without solids plugging agent as described in any one of claims 1-8, characterized in that, Includes the following steps: S1, calculate the amount of sealing agent used, and calculate the required number of chemical cavities based on the amount of sealing agent used; S2, the tool installation connects the lower mechanism of the drug chamber, the drug chamber and the upper mechanism of the drug chamber in order from bottom to top. After the connection is completed, inject the non-solid phase plugging agent into the drug chamber. After the non-solid phase plugging agent is filled, it is sealed by the injection plug wire. Then connect the plugging packer to the lower connector (16). The upper part of the plugging packer is connected to the drill rod. S3, After the plugging packer is set and the plugging operation drill is lowered to the predetermined well depth for plugging, an aluminum alloy ball is dropped into the wellhead. After the aluminum alloy ball falls into the interceptor (17), the first pressurization is applied to shear the suspension pin (33). Then, the second pressurization is applied. After the rubber sleeve (8) is compressed along the axial direction and expands radially, the plugging packer begins to set. During this process, the escape mechanism also moves and forms a self-locking mechanism, which makes the rubber sleeve (8) expand and form a stable seal with the well wall. After the plugging packer is firmly set, the pressure is continuously increased, the shear pin (18) is sheared, and the balance piston (20) and the agent piston (23) move down to push the agent chamber (22). The pressure is continuously increased to shear the release pin (27). The agent piston (23) pushes the non-solid phase plugging agent in the agent chamber to be released from the release hole of the basket (24) into the wellbore leakage layer. S4. After the plugging operation is completed, the drill pipe is pulled up, the escapement mechanism is disengaged and locked, and the rubber sleeve (8) returns to its original shape due to its own elasticity. After the plugging packer is unsealed, the drill is pulled up. After the drill is pulled up to a safe well section, the leakage is tested by a large-volume circulating mud to verify whether the plugging was successful.

10. The targeted leak sealing construction process as described in claim 9, characterized in that, In step S4, when the drill string is pulled up, when the tool for sending the non-solid plugging agent is introduced, the plugging packer is first disassembled, and then the upper structure of the agent chamber, the agent chamber, and the lower structure of the agent chamber are disassembled in sequence. When the plugging agent is solidified inside the wellbore during the tripping process, first pull the plugging packer out of the wellhead, then lower the drill bit to continue drilling.

11. The targeted leak sealing construction process as described in claim 9, characterized in that: In step S2, the solid-free sealing agent is a solvent-free, single-component, nano-reinforced polyurethane grouting material, prepared by the following method: Step 1: 70-100 parts by weight of polyether polyol, 0-30 parts by weight of polyester polyol and 45-50 parts by weight of polyisocyanate are subjected to polymerization reaction to obtain polyurethane prepolymer. Step 2: Mix the polyurethane prepolymer obtained in Step 1 with the catalyst, surfactant, plasticizer, toughening agent and nano-reinforcing agent to obtain a solvent-free single-component nano-reinforced polyurethane grouting material.

12. The targeted leak sealing construction process as described in claim 11, characterized in that, Step 1 involves the following steps: at 60℃ to 100℃, polyether polyol and polyester polyol are vacuum dehydrated and degassed for 2 to 3 hours, and then cooled to 48 to 52℃ to add polyisocyanate to carry out a polymerization reaction to obtain polyurethane prepolymer.

13. The targeted leak sealing construction process as described in claim 12, characterized in that: The amount of catalyst used is 1% to 5% of the mass of the polyurethane prepolymer; The amount of the surfactant used is 0.5% to 2% of the mass of the polyurethane prepolymer; The amount of plasticizer used is 6% to 12% of the mass of the polyurethane prepolymer; The amount of toughening agent used is 1% to 5% of the mass of the polyurethane prepolymer; The amount of the nano-reinforcing agent is 0.3% to 1% of the mass of the polyurethane prepolymer.

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