High-pressure-bearing plugging agent for shaft integrity treatment and preparation method of high-pressure-bearing plugging agent

Abstract

The invention discloses a high-pressure-bearing plugging agent for shaft integrity treatment and a preparation method of the high-pressure-bearing plugging agent. The high-pressure-bearing plugging agent is prepared from the following components in parts by mass: an agent A: 5 to 10 parts of waterborne polyurethane acrylate, 10 to 15 parts of olefine acid monomer, 0.1 to 0.5 part of plasticizer, 0.1 to 0.3 part of dispersing agent, 20 to 40 parts of water, 3 to 8 parts of hydrophilic fiber, 1 to 2.5 parts of nano filler and 0.2 to 0.3 part of sodium salt; and the agent B comprises the following components in parts by weight: 0.1-5 parts of a curing agent, 0.01-0.1 part of an accelerant and 10-20 parts of water. The invention further provides a preparation method of the high-pressure-bearing plugging agent for shaft integrity treatment. According to the high-pressure-bearing plugging agent for shaft integrity treatment and the preparation method of the high-pressure-bearing plugging agent, polyurethane acrylate is adopted as a main plugging material, and the high-pressure-bearing plugging agent is good in plugging effect, high in pressure-bearing capacity, less affected by the environment such as temperature and pressure, good in corrosion resistance and capable of achieving circulating plugging removal.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas well development engineering, and relates to a high-pressure bearing plugging agent for wellbore integrity treatment and a preparation method thereof. Background Technique

[0002] Wellbore integrity is a comprehensive technical, operational and organizational management solution to reduce the risk of uncontrolled leakage of formation fluids in oil and gas wells throughout their life cycle. Its core is to establish effective wellbore barriers at each wellbore stage. Wellbore integrity can be extended to mean that the pressure isolation, sealing or closure between various spaces in the wellbore is good during its life cycle. These spaces include, but are not limited to, the space between the wellhead oil casing head, the space between the tubing and the production casing, the space between each casing, the space formed by the tubing assembly, etc. Due to the harsh wellbore environment and long production cycle, after a period of time, problems with wellbore integrity will occur. Every year, the maintenance, production restriction or shutdown caused by integrity problems brings billions of dollars in losses to the oil industry.

[0003] For example, during the drilling process, due to strong formation permeability, the existence of natural holes, fractures, faults and other low-pressure coefficient formations, resulting in a positive pressure difference of the drilling fluid on the formation; or during the oil and gas production and water injection processes, there is an imbalance, causing the density of the drilling fluid to be too high, resulting in a positive pressure difference of the drilling fluid on the formation; or during the casing running process, due to operations such as early pump shutdown, late pump startup or low annular return velocity by operators, resulting in a high concentration of cuttings, and well leakage occurs when the pump is restarted. There may also be well leakage problems such as not circulating during lowering the drill pipe, the speed of lowering the drill pipe, and inappropriate weighting in the oil-bearing interval.

[0004] Therefore, well leakage is very likely to occur during the drilling and oil and gas production processes. Therefore, the plugging of the wellbore has become a key process for maintaining wellbore integrity. In the prior art, the plugging means for treating severe well leakage is still mainly the inorganic gel plugging technology based on cement. However, the inorganic gel plugging technology has a short plugging validity period, and its plugging strength and plugging effect are greatly affected by the environment, such as temperature and formation water content. Therefore, it is urgent to propose some new plugging agents. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-pressure bearing plugging agent for wellbore integrity treatment and a preparation method thereof. Polyurethane acrylate is used as the main plugging material, which has good plugging effect, strong pressure-bearing capacity, is less affected by environmental factors such as temperature and pressure, and has good corrosion resistance, and can also achieve cyclic plugging and unplugging.

[0006] The present invention is realized through the following technical solutions: In the first aspect, a high-pressure bearing plugging agent for wellbore integrity treatment and a preparation method thereof include the following components in parts by mass: Agent A 5 - 10 parts of waterborne polyurethane acrylate, 10 - 15 parts of acrylic monomer, 0.1 - 0.5 parts of plasticizer, 0.1 - 0.3 parts of dispersant, 20 - 40 parts of water, 3 - 8 parts of hydrophilic fiber, 1 - 2.5 parts of nano filler, 0.2 - 0.3 parts of sodium salt; Agent B 0.1 - 5 parts of curing agent, 0.01 - 0.1 parts of accelerator, 10 - 20 parts of water.

[0007] To better implement the present invention, further, the curing agent is at least one of ammonium persulfate, potassium persulfate, hydrogen peroxide, benzoyl peroxide, cyclohexanone peroxide; and / or The accelerator is at least one of triethanolamine, sodium bisulfite, sodium thiosulfate, ferrous chloride, propylenediamine, ethylenediaminediacetic acid, N - nitrosotoluidine.

[0008] To better implement the present invention, further, the plasticizer is at least one of dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, tricresyl phosphate, tricresyl phosphate, diphenyl isoneopentyl phosphate alkyl benzene sulfonate.

[0009] To better implement the present invention, further, the hydrophilic fiber is selected from at least one of polypropylene fiber, polyvinyl alcohol fiber, hydrophilic polyurethane fiber, hydroxymethyl cellulose fiber, hydroxyethyl cellulose fiber, polyvinylamine fiber.

[0010] To better implement the present invention, further, the diameter of the hydrophilic fiber is 1 - 10 μm.

[0011] To better implement the present invention, further, the nano filler is at least one of nano - silica, nano - titania, nano - alumina, nano - titanium nitride, nano - titanium carbide, nano - titanium carbonitride, nano - barium sulfate, nano - calcium carbonate.

[0012] To better implement the present invention, further, the dispersant is selected from any one of coupling agent or triethylenetetramine.

[0013] To better implement the present invention, further, the salt is any one of sodium carbonate, sodium bicarbonate or sodium chloride.

[0014] In a second aspect, the present application also provides a preparation method of the high - pressure - bearing plugging agent for wellbore integrity treatment described in the first aspect above, including the following steps: Dissolve the salt in water to obtain brine; mix the dispersant and the filler in water to obtain a pretreated filler; Mix the hydrophilic fiber, polyurethane acrylate, acrylic monomer, plasticizer, and pretreated filler with the brine, and stir evenly to obtain Agent A; Mix the curing agent and accelerator with water to obtain Agent B; Mix Agent A and Agent B to obtain a high-pressure plugging agent for wellbore integrity treatment.

[0015] To better implement the present invention, further, the high-pressure plugging agent is prepared and used immediately.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The present invention uses a water-swellable waterborne polyurethane acrylate and an acrylic monomer that can copolymerize with it as the main polymer components, so that a network-like polyurethane acrylate copolymer that can undergo a polymerization reaction to form a network and swell in water can be formed in the formation, and its plugging effect is excellent; moreover, since the polyurethane acrylate polymer is a high-elastic material, it can further squeeze the leakage point under the pressure difference in the wellbore. Compared with rigid plugging materials, its plugging effect is better and it is not easily damaged twice. Moreover, since the polyurethane acrylate is a water-swellable polymer material, the plugging agent can also be blocked and plugged multiple times, and it only needs to adjust the injection water / dry state of the plugging point to achieve the plugging / unplugging cycle.

[0017] (2) The plugging agent provided by the present invention adds hydrophilic fibers to improve and enhance the hydrophilicity of the polyurethane acrylate. It can not only increase the swelling multiple of the plugging agent and optimize the plugging effect, but also enhance the compressive strength of the plugging agent, making its pressure-bearing effect better. Moreover, the added hydrophilic fibers also have a certain bonding strength in a high-humidity environment, enabling the plugging agent to bond to the plugging point during plugging. Even after drying and unplugging, the plugging agent can be fixed at the plugging point as much as possible, which is beneficial for re-plugging the original plugging point.

[0018] (3) The present invention uses waterborne polyurethane acrylate as one of the prepolymers for polymerization, so that it can be dispersed in water and uses water as a solvent, avoiding the use of organic solvents and avoiding organic solvent pollution of the formation; moreover, the formed polymer has stronger hydrophilicity, can have better water-swellable ability, improve the plugging effect and reduce the dosage of the plugging agent.

[0019] (4) The plugging agent provided by the present invention also adds inorganic fillers, which can not only improve strength, heat resistance, and wear resistance, but also the inorganic fillers provided in this application are added to the plugging agent after being pretreated with a dispersant. They not only have good dispersibility, but also can be grafted onto the active groups of the polymer through reaction during the polymerization reaction, further improving the bending strength and impact strength of the polymer and further enhancing the compressive performance of the plugging agent.

[0020] (5) In the plugging agent provided by the present invention, the main plugging material is less affected by temperature, pressure, and formation water, has strong compressive capacity, strong corrosion resistance, and better plugging effect. Embodiment

[0021] The following detailed descriptions are all illustrative and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the present invention clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, components, components, and / or combinations thereof.

[0023] The inventor provides a high-pressure resistant plugging agent for wellbore integrity treatment in this application, which includes the following components in parts by mass: Agent A 5-10 parts of waterborne polyurethane acrylate, 10-15 parts of acrylic acid monomer, 0.1-0.5 parts of plasticizer, 0.1-0.3 parts of dispersant, 20-40 parts of water, 3-8 parts of hydrophilic fiber, 1-2.5 parts of nano filler, 0.2-0.3 parts of sodium salt; Agent B 0.1-5 parts of curing agent, 0.01-0.1 parts of accelerator, 10-20 parts of water.

[0024] The waterborne polyurethane acrylate is a waterborne polyurethane, such as a castor oil-based polyurethane, and an acrylate ester, such as ethyl acetate and butyl acrylate, polymerize to form a network polymer. It has interpenetrating polyurethane molecular chains and acrylate ester molecular chains, forming a structure similar to a core-shell structure. When Agent A and Agent B are mixed, the C=C double bonds on the waterborne polyurethane acrylate can copolymerize with acrylate monomers, such as acrylic acid, to form a polymer with a network structure, achieving plugging. And this polymer can foam and expand when encountering water, generating secondary pressure to expand the plugging volume, and its plugging effect is good. Moreover, compared with polyurethane foaming materials and polyurethane acrylate that has not copolymerized with acrylate monomers, this polymer has a small water swelling rate, better weather resistance and wear resistance, and is not prone to embrittlement in water or oil for a long time. This is because this polymer adds a block of polyacrylic acid with good weather resistance, wear resistance and adhesion, making it have better corrosion resistance and compressive properties, and a large number of spaces that allow water molecules to enter are formed between the polymerized groups, enabling water molecules to enter, increasing the swelling multiple, and improving both its plugging performance and compressive properties. The pressure-bearing capacity of the plugging agent provided in this application can reach more than 100 MPa.

[0025] Among them, the waterborne polyurethane acrylate in Agent A has good hydrophilicity and can be evenly dispersed in water to form emulsion particles, enabling the polymer plugging agent not to require the addition of a large amount of organic solvents, avoiding the pollution of the formation by organic solvents and reducing costs.

[0026] The preparation method of the waterborne polyurethane acrylate, such as the polyurethane acrylate formed by castor oil-based polyurethane and acrylate ester, is a mature preparation method and has already been a mature preparation means, so it will not be elaborated one by one in this application. Those skilled in the art can prepare it through existing technologies or directly purchase it commercially.

[0027] In some embodiments, the addition amounts of the waterborne polyurethane acrylate and the acrylate monomer are adjusted within a certain range so that the proportion of the NCO group in the obtained polymer is not higher than 0.1% by mass fraction of the polyurethane acrylate, which can ensure the hydrophilic property of the polyurethane acrylate particles and improve its swelling multiple. When selecting, the proportion of the NCO group on the waterborne polyurethane acrylate can be controlled within the range of 5-9% by mass fraction on the waterborne polyurethane acrylate.

[0028] In some embodiments, the hydrophilic fiber is selected from at least one of polypropylene fiber, polyvinyl alcohol fiber, hydrophilic polyurethane fiber, hydroxymethyl cellulose fiber, hydroxyethyl cellulose fiber, and polyvinylamine fiber.

[0029] In some embodiments, the diameter of the hydrophilic fiber is 1 to 10 μm, so as to facilitate its better dispersion in Agent A, improve the hydrophilicity of the polyurethane acrylate, be conducive to its water absorption, and increase the swelling ratio; at the same time, it can also improve the compressive strength and surface adhesion performance.

[0030] In some embodiments, the plasticizer is at least one of dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, tricresyl phosphate, tricresyl phosphate, diphenyl isoneodecyl phosphate alkyl benzene sulfonate, etc., to reduce the viscosity of the system and enable the reaction to proceed better.

[0031] In some embodiments, the nano filler is at least one of nano silica, nano titanium dioxide, nano alumina, nano titanium nitride, nano titanium carbide, nano titanium carbonitride, nano barium sulfate, nano calcium carbonate. Preferably, the nano filler does not select fillers with water swelling properties. This is because the water swelling rate of the nano filler is different from that of the polymer, and its water adsorption effect is also different. Therefore, during the process of water swelling and water loss recovery, it is easy to form more complex and larger internal stress changes, affecting the stability of the material.

[0032] In some embodiments, the dispersant is selected from any one of coupling agents or triethylenetetramine. Preferably triethylenetetramine, to modify active groups on the surface of nano fillers such as silica, titanium dioxide, alumina, etc., which can react with the above-mentioned polyurethane acrylate and graft onto the polyurethane acrylate. This can not only improve the dispersion of nano fillers in the polymer, but also improve the strength and toughness of the polymer.

[0033] In some embodiments, the sodium salt is any one of sodium carbonate, sodium bicarbonate, and sodium chloride. It is formed in the system to increase the ionic concentration of the system, catalyze the copolymerization reaction of polyurethane acrylate and acrylic acid monomer, enable it to quickly form a solidified plugging material, and make the plugging agent take effect quickly.

[0034] In a second aspect, the present application also provides a preparation method of the high-pressure bearing plugging agent for wellbore integrity treatment described in the first aspect above, including the following steps: Dissolve salt in water to obtain brine; mix a dispersant and the filler in water to obtain a pretreated filler; Mix the hydrophilic fiber, polyurethane acrylate, acrylic acid monomer, plasticizer, and pretreated filler with the brine, and stir evenly to obtain Agent A; Mix a curing agent and an accelerator with water to obtain Agent B; Mix Agent A and Agent B to obtain a high-pressure bearing plugging agent for wellbore integrity treatment.

[0035] Among them, the high-pressure plugging agent is prepared and used immediately, or can be injected simultaneously during injection. Through its flow state during the injection process, agent A and agent B are mixed, and then a copolymerization reaction occurs to form a plugging material.

[0036] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Embodiment

[0037] This embodiment provides a high-pressure plugging agent for wellbore integrity treatment. The plugging agent includes: Agent A 5 parts of waterborne polyurethane acrylate (aqueous polyurethane acrylate emulsion formed by castor-based polyurethane and butyl acrylate), 10 parts of acrylic acid, 0.1 part of dibutyl phthalate, 0.1 part of coupling agent KH550, 20 parts of water, 3 parts of polypropylene fiber, 1 part of nano-silica (average particle size 25nm), 0.2 part of sodium carbonate; Agent B 1 part of ammonium persulfate, 0.04 part of triethanolamine, 10 parts of water; Add sodium carbonate to 3 parts of water and stir until the sodium carbonate is completely dissolved to obtain brine; Add the coupling agent to 17 parts of water, then add nano-silica, and stir at 60°C for 20 minutes to obtain pretreated nano-fillers; Add waterborne polyurethane acrylate, acrylic acid, dibutyl phthalate, polypropylene fiber and brine to the pretreated nano-fillers to obtain agent A for standby.

[0038] Add ammonium persulfate and triethanolamine to water and stir and mix evenly to obtain agent B for standby. Embodiment

[0039] This embodiment provides a high-pressure plugging agent for wellbore integrity treatment. The plugging agent includes: Agent A 10 parts of waterborne polyurethane acrylate (aqueous polyurethane acrylate emulsion formed by castor-based polyurethane and butyl acrylate), 15 parts of acrylic acid, 0.3 part of dibutyl phthalate, 0.3 part of coupling agent KH550, 40 parts of water, 5 parts of polypropylene fiber, 2 parts of nano-silica (average particle size 25nm), 0.25 part of sodium carbonate; Agent B 2 parts of ammonium persulfate, 0.08 part of triethanolamine, 20 parts of water; Add sodium carbonate to 10 parts of water and stir until the sodium carbonate is completely dissolved to obtain brine; Add the coupling agent to 30 parts of water, then add nano-silica, and stir at 60°C for 20 min to obtain pretreated nano-fillers; Add waterborne polyurethane acrylate, acrylic acid, dibutyl phthalate, polypropylene fiber and brine to the pretreated nano-fillers to obtain Agent A for standby.

[0040] Add ammonium persulfate and triethanolamine to water, stir and mix evenly to obtain Agent B for standby. Example

[0041] This example provides a high-pressure plugging agent for wellbore integrity treatment. The plugging agent includes: Agent A 8 parts of waterborne polyurethane acrylate (aqueous polyurethane acrylate emulsion formed by castor-based polyurethane and butyl acrylate), 12 parts of acrylic acid, 0.25 part of dibutyl phthalate, 0.2 part of coupling agent KH550, 35 parts of water, 4 parts of polypropylene fiber, 1.5 parts of nano-silica (average particle size 25 nm), 0.3 part of sodium carbonate; Agent B 3 parts of ammonium persulfate, 0.05 part of triethanolamine, 15 parts of water; Add sodium carbonate to 5 parts of water, stir to completely dissolve the sodium carbonate to obtain brine; Add the coupling agent to 30 parts of water, then add nano-silica, and stir at 60°C for 20 min to obtain pretreated nano-fillers; Add waterborne polyurethane acrylate, acrylic acid, dibutyl phthalate, polypropylene fiber and brine to the pretreated nano-fillers to obtain Agent A for standby.

[0042] Add ammonium persulfate and triethanolamine to water, stir and mix evenly to obtain Agent B for standby.

[0043] Conduct a plugging ability test on the plugging agents prepared in Examples 1-3 of the present invention. Test method: Fill different particle size sands in the sand-filled pipe to simulate irregular perforation holes and formation hole structures (hole diameter 0-2.0 cm). Slowly inject the freshly prepared plugging agent from one end of the sand-filled pipe until the injection pressure rises to the designed injection pressure; when no liquid flows out from the other end of the sand-filled pipe, keep the pressure stable for 240 min and observe the plugging effect. Change the ambient temperature of the sand-filled pipe and observe the plugging effect at different temperatures. The test results are shown in Table 1:

[0044] As can be seen from Table 1, for the plugging agent provided in this application, the influence of temperature, pressure, etc. on it is small, and it can still maintain good plugging ability under high temperature and high pressure.

[0045] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modifications and equivalent changes made to the above embodiments based on the technical essence of the present invention all fall within the protection scope of the present invention.

Claims

1. A high-pressure plugging agent for wellbore integrity management, characterized in that, Comprising the following components in parts by mass: Agent A 5 - 10 parts of aqueous polyurethane acrylate, 10 - 15 parts of acrylic monomer, 0.1 - 0.5 parts of plasticizer, 0.1 - 0.3 parts of dispersant, 20 - 40 parts of water, 3 - 8 parts of hydrophilic fiber, 1 - 2.5 parts of nano - filler, 0.2 - 0.3 parts of sodium salt; Agent B 0.1 - 5 parts of curing agent, 0.01 - 0.1 parts of accelerator, 10 - 20 parts of water.

2. The high-pressure plugging agent for wellbore integrity treatment according to claim 1, wherein: The curing agent is at least one of ammonium persulfate, potassium persulfate, hydrogen peroxide, benzoyl peroxide, cyclohexanone peroxide; and / or The accelerator is at least one of triethanolamine, sodium bisulfite, sodium thiosulfate, ferrous chloride, propylenediamine, ethylenediaminediacetic acid, N - nitrosotoluidine.

3. The high-pressure plugging agent for wellbore integrity management according to claim 1, characterized in that: The plasticizer is at least one of dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, tricresyl phosphate, tricresyl phosphate, diphenyl isoneodecyl phosphate alkyl benzene sulfonate.

4. The high-pressure plugging agent for wellbore integrity treatment according to claim 1, characterized in that: The hydrophilic fiber is selected from at least one of polypropylene fiber, polyvinyl alcohol fiber, hydrophilic polyurethane fiber, hydroxymethyl cellulose fiber, hydroxyethyl cellulose fiber, polyvinylamine fiber.

5. A high-pressure leak stopper for wellbore integrity management according to claim 4, characterized in that: The diameter of the hydrophilic fiber is 1 - 10 μm.

6. The high-pressure plugging agent for wellbore integrity treatment according to claim 1, characterized in that: The nano - filler is at least one of nano - silica, nano - titanium dioxide, nano - alumina, nano - titanium nitride, nano - titanium carbide, nano - titanium carbonitride, nano - barium sulfate, nano - calcium carbonate.

7. The high-pressure plugging agent for wellbore integrity treatment according to claim 1, characterized in that: The dispersant is selected from any one of coupling agent or triethylenetetramine.

8. The high-pressure plugging agent for wellbore integrity treatment according to claim 1, characterized in that: The salt is any one of sodium carbonate, sodium bicarbonate or sodium chloride.

9. The preparation method of a high-pressure plugging agent for wellbore integrity management according to claim 1, characterized in that: Comprising the following steps: Dissolve the salt in water to obtain brine; mix the dispersant and the filler in water to obtain pretreated filler; Mix the hydrophilic fiber, polyurethane acrylate, acrylic monomer, plasticizer and pretreated filler with the brine and stir evenly to obtain Agent A; Mix the curing agent and accelerator with water to obtain Agent B; Mix Agent A and Agent B to obtain a high - pressure plugging agent for wellbore integrity treatment.

10. The preparation method of the high-pressure plugging agent for wellbore integrity management according to claim 9, characterized in that, The high - pressure plugging agent is prepared and used immediately.

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