CN114507515B - A supramolecular gel plugging agent for fractured formations and its preparation method and application - Google Patents

Abstract

The invention provides a supramolecular gel plugging agent for fractured formations, a preparation method and application thereof. The supramolecular gel plugging agent of the present invention includes the following raw materials in mass percentage: 18-45% of comonomer, 0.5-6.0% of surfactant, 0.1-2.0% of initiator, 0.1-2.0% of cosolvent, accelerator 0.05-0.5%, saline solution 0.5-5%, and the balance is water; the copolymerization monomer is a combination of hydrophilic monomer, hydrophobic monomer and functional group molecules. The present invention also provides a preparation method of the above lost circulation agent. The gel plugging agent of the present invention not only has the advantages of good matching between gel leak-proof plugging materials and cracks, but also has high temperature and pressure resistance, has unique dynamic reversible characteristics, and can effectively plug leaks An overall compact sealing layer is formed; at the same time, the supramolecular gel plugging agent has excellent mechanical properties and environmental responsiveness.

Description

A supramolecular gel plugging agent for fractured formations and its preparation method and application

Technical Field

The invention relates to a supramolecular gel plugging agent for fractured strata and a preparation method and application thereof, belonging to the technical field of drilling fluid plugging.

Background Art

At present, in the complex oil and gas reservoir drilling projects, the problem of well leakage has become particularly prominent, especially the problem of vicious leakage in fractured formations. Well leakage often occurs in formations with relatively developed holes, cracks, and holes. According to the leakage channel, it can be divided into pore leakage, fracture leakage and cave leakage. The vast majority of well leakage is related to fractures. According to statistics, the cost of plugging fracture leakage accounts for more than 90% of the total cost of well leakage. Due to its serious obstruction to drilling work and serious threat to drilling safety, drilling fluid plugging has become a "neck-stuck" problem that restricts the further development of China's exploration and development. Therefore, solving the problem of vicious leakage in the drilling process has become a top priority for the oil industry.

Plugging materials are the basis and key to plugging technology. Conventional plugging materials have achieved good results in dealing with permeability and small and medium-sized fracture well leakage, but their adaptability to plugging large cracks or crack holes is poor, and the success rate of one-time plugging is low. Fiber and rigid materials are commonly used plugging materials in oil fields. They have poor compatibility with cracks and are very likely to cause sealing. The plugging effect still needs to be improved. Polymer gel plugging agent is one of the commonly used and effective plugging agents. By injecting a certain amount of gel plugging agent solution into the leakage layer, the cracks are sealed after solidification, which plays a role in isolating the drilling fluid from the formation fluid. Among them, the performance of the gel plugging agent is the key to the success of plugging. The gel plugging agent currently used has achieved relatively good results in field application, but with the expansion of oil and gas exploration and development to deep layers, high temperature and high pressure have become one of the main problems faced by drilling plugging, and higher requirements have been put forward for the temperature and salt resistance and pressure plugging performance of the gel plugging agent.

In response to the above problems, Chinese patent document CN111961452A provides a high-temperature resistant and high-strength thixotropic gel plugging agent, which has the advantages of high temperature resistance, high strength and thixotropy, but the controllability of gelation needs to be improved; Chinese patent document CN110734751A provides a high-temperature resistant composite reinforced gel plugging agent, which has the characteristics of high temperature resistance and delayed expansion, but insufficient salt resistance and pressure bearing capacity; Chinese patent document CN112480886A provides a polymer gel composite plugging agent, which has good water absorption and expansion properties, but lacks heat and salt resistance and gelation strength.

Supramolecular gel forms a gel network system with reversible structure and high performance characteristics under the self-assembly of non-covalent bond interactions. Supramolecular gel plugging agent not only has the advantages of good matching between conventional gel plugging materials and cracks, but also has excellent temperature and salt resistance and shear thixotropy, can fully fill the leakage space, has high mechanical strength, can achieve long-term plugging of the leakage layer, and can effectively solve the shortcomings of conventional plugging materials.

Therefore, it is necessary to develop a supramolecular gel plugging agent with both mechanical properties and environmental responsiveness to solve the problem of vicious leakage in fractured, high-temperature and high-salt formations encountered during drilling.

Summary of the invention

In view of the shortcomings of the prior art, especially the complex preparation process of the gel leak-proofing/plugging materials conventionally used in existing fractured formations, insufficient pressure-bearing and plugging capacity, and poor temperature and salt resistance, the present invention provides a supramolecular gel plugging agent for fractured formations, and a preparation method and application thereof.

The supramolecular gel plugging agent of the present invention is a gel plugging agent with excellent mechanical properties and outstanding environmental responsiveness formed based on non-covalent bond interactions. It not only has the advantages of good matching between gel-type leak-proof plugging materials and cracks, but also increases the temperature and pressure resistance of the gel through supramolecular structure design, has unique dynamic reversible characteristics, and can effectively plug leaks to form an overall tight sealing plugging layer; at the same time, the supramolecular gel plugging agent has excellent mechanical properties and environmental responsiveness, introduces multiple hydrogen bond structural units into the hydrophobic chain of the hydrophobic associating polymer, and introduces zwitterionic groups at its hydrophilic end to form a supramolecular gel with high strength and environmental responsiveness, which can adaptively match cracks of complex scales, fully fill the leakage space, and achieve long-term stable plugging.

The technical solution of the present invention is as follows:

A supramolecular gel plugging agent for fractured formations comprises the following raw materials in percentage by mass: 18-45% copolymerization monomers, 0.5-6.0% surfactant, 0.1-2.0% initiator, 0.1-2.0% cosolvent, 0.05-0.5% promoter, 0.5-5% salt water solution, and the balance is water; the copolymerization monomers are a combination of hydrophilic monomers, hydrophobic monomers and functionalized group molecules.

Preferably according to the present invention, the supramolecular gel plugging agent for fractured formations comprises the following raw materials in percentage by mass: 24-35% copolymerization monomer, 3-5% surfactant, 0.4-1% initiator, 0.5-1% cosolvent, 0.2-0.5% promoter, 1-3% brine solution, and the balance is water.

Preferably according to the present invention, the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule in the copolymerization monomer is 6-8:1-3:1, and more preferably 7:2:1.

According to the present invention, the hydrophilic monomer is preferably acrylamide, acrylic acid, methacrylic acid, sodium acrylate, polyethylene glycol, N-isopropylacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyldimethylallyl ammonium chloride, N-dodecylacrylamide, N-vinylpyrrolidone, 2-vinylpyridine, and a combination of two or more of N-hydroxyethylacrylamide; further preferably, it is a combination of two or more of acrylamide, acrylic acid, methacrylic acid, sodium acrylate, polyethylene glycol, N-isopropylacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, hexadecyldimethylallyl ammonium chloride, 2-vinylpyridine, and N-vinylpyrrolidone.

According to the present invention, the hydrophobic monomer is preferably a combination of two or more of octadecyl methacrylate, methyl methacrylate, butyl methacrylate, hexadecyl methacrylate, polyhydroxyethyl methacrylate, dimethylaminoethyl methacrylate, 2-ethyl methacrylate, β-hydroxyethyl methacrylate, lauryl methacrylate, 4-trifluoromethylethylene carbonate (CAS No.: 167951-80-6), and 4-methylstyrene; further preferably, it is a combination of two or more of octadecyl methacrylate, lauryl methacrylate, hexadecyl methacrylate, butyl methacrylate, dimethylaminoethyl methacrylate, 4-methylstyrene and polyhydroxyethyl methacrylate.

Preferably according to the present invention, the functional group molecule is one or a combination of two or more of scleroglucan, chitosan, sodium alginate, 18-crown-6, cyclodipeptide, β-cyclodextrin, calix[6]arene, diethoxycollagen[5]arene, and cucurbituril; further preferably, it is a combination of two or more of scleroglucan, chitosan, sodium alginate, β-cyclodextrin, calix[6]arene, and cucurbituril.

Preferably according to the present invention, the surfactant is one or a combination of two or more of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, dodecylphenol polyoxyethylene ether, stearic acid, sorbitan fatty acid, betaine, and polysorbate.

Preferably according to the present invention, the initiator is one or a combination of two or more of diisopropyl peroxydicarbonate, tert-butyl perbenzoate, isopropylbenzene hydroperoxide, potassium persulfate, ammonium persulfate, azobisisobutyl ester, dimethyl azobisisobutyrate, azobisisobutylimidazoline hydrochloride, and sodium sulfite.

Preferably according to the present invention, the co-solvent is a sulfate and/or a nitrogen-containing compound, and further preferably a combination of a sulfate and a nitrogen-containing compound, wherein the mass ratio of the sulfate to the nitrogen-containing compound is 1-2:1; the sulfate is anhydrous sodium sulfate or anhydrous calcium sulfate, and the nitrogen-containing compound is urea or ammonium chloride.

Preferably according to the present invention, the accelerator is one or a combination of two or more of 1,2-bis(dimethylamino)ethane, triethylenediamine, ferric chloride, tetramethylthiourea, vanadium acetylacetonate, acetylacetone, N,N-dimethyl-p-toluidine, triethylamine, tetrahydroquinoline, 8-hydroxyquinoline, and ferrocene; more preferably, a combination of triethylenediamine and N,N-dimethyl-p-toluidine.

Preferably according to the present invention, the saline solution is a sodium chloride aqueous solution and/or a potassium chloride aqueous solution, more preferably a sodium chloride aqueous solution; the concentration of the saline solution is 0.5-5 mol/L, more preferably 2-3 mol/L.

According to the present invention, the method for preparing the supramolecular gel plugging agent for fractured formations comprises the following steps:

(1) adding the hydrophilic monomer in the copolymerization monomer into water and stirring to obtain a mixed solution A;

(2) adding a hydrophobic monomer in the copolymerization monomer to the mixed solution A, and stirring evenly to obtain a mixed solution B;

(3) adding functional group molecules and surfactants to mixed solution B, and stirring to obtain mixed solution C;

(4) adding the initiator and the co-solvent to the mixed solution C and stirring until they are completely dissolved to obtain a mixed solution D;

(5) adding an accelerator and a saline solution to the mixed solution D, stirring the mixture to obtain a mixed solution E;

(6) The mixed solution E is deoxygenated and then allowed to stand for reaction to obtain a supramolecular gel; the supramolecular gel is dried and crushed to obtain a supramolecular gel plugging agent for fractured formations.

Preferably according to the present invention, in step (1), the stirring temperature is 20-45°C, more preferably 25-30°C; the stirring speed is 300-1000 rpm, more preferably 400-600 rpm; the stirring time is 10-40 minutes, more preferably 20-30 minutes.

Preferably according to the present invention, in step (2), the stirring temperature is 20-50°C, more preferably 23-28°C; the stirring speed is 200-800 rpm, more preferably 450-580 rpm; and the stirring time is 5-30 minutes, more preferably 24-28 minutes.

Preferably according to the present invention, in step (3), the stirring temperature is 30-50°C, more preferably 35-40°C; the stirring speed is 400-1000 rpm, more preferably 500-700 rpm; the stirring time is 30-60 minutes, more preferably 40-50 minutes.

Preferably according to the present invention, in step (4), the stirring temperature is 30-70°C, more preferably 40-50°C; the stirring speed is 400-800 rpm, more preferably 500-600 rpm; the stirring time is 20-40 minutes, more preferably 25-35 minutes.

Preferably according to the present invention, in step (5), the stirring temperature is 30-70°C, more preferably 40-60°C; the stirring speed is 400-800 rpm, more preferably 450-550 rpm; the stirring time is 20-40 minutes, more preferably 25-30 minutes.

Preferably, in step (6), the deoxygenation and degassing method is to introduce nitrogen and reduce pressure to evacuate; the temperature of the static reaction is 50-80°C, more preferably 60-65°C; the static reaction time is 5-9 hours, more preferably 6-7 hours.

According to the preferred embodiment of the present invention, the drying in step (6) is vacuum drying at 55-80°C for 20-30 hours, and more preferably vacuum drying at 70-75°C for 24-26 hours. The pulverization is to pulverize the supramolecular gel into particles of different sizes using a pulverizer according to different requirements.

According to the present invention, the supramolecular gel plugging agent for fractured formations is used in plugging fractured formations.

Preferably, according to the present invention, the supramolecular gel plugging agent for fractured formations is used as a plugging material for drilling fluid plugging, and its addition amount is 2%-5% of the mass of the drilling fluid, and can be injected by injection while drilling.

The preparation principle of the present invention is as follows:

The present invention adopts a free radical polymerization method to form a supramolecular gel based on non-covalent bond interaction suitable for fractured strata through self-assembly between copolymerization monomers. The main raw materials of copolymerization monomers are hydrophilic monomers, hydrophobic monomers and functionalized group molecules. Hydrophilic monomers and hydrophobic monomers can undergo hydrophobic association under the action of surfactants to form hydrophobic associating polymers. The molecular chains of hydrophobic associating polymers carry a small amount of hydrophobic groups, which can form a supramolecular structure with a three-dimensional network in the solution, so that the polymer has good temperature resistance, salt resistance and dilution resistance at low concentrations and low molecular weights. Through supramolecular structure design, the multiple hydrogen bond structural units formed in the copolymerization process are introduced into the hydrophobic chain of the hydrophobic associating polymer, and zwitterionic groups are introduced at its hydrophilic end to form a supramolecular gel with unique dynamic reversible characteristics and self-repairing ability, which can effectively improve the mechanical strength of the supramolecular gel. At the same time, the mutual entanglement of functionalized group molecules can improve the mechanical properties and environmental responsiveness of the gel, and the supramolecular gel formed based on the host-guest effect can maintain good uniformity and environmental responsiveness within a certain scale range.

The technical features and beneficial effects of the present invention are as follows:

1. The supramolecular gel for fractured strata of the present invention is used as a plugging material for drilling fluid plugging. The granular gel is injected into the leakage layer while drilling. The charged particles in the gel particles are adsorbed on the rock surface under the action of static electricity, plugging micro-cracks, pores or high-permeability layers. After extrusion deformation, water absorption expansion and filling accumulation, a high-strength supramolecular gel is formed, which can effectively improve the pressure bearing capacity of the formation and realize intelligent plugging.

2. The supramolecular gel for fractured formations of the present invention has excellent mechanical properties and environmental responsiveness. The ionic groups on the surface of the gel particles can be adsorbed on the surface of the formation rock through hydrogen bonds and electrostatic effects. They are interconnected through aggregation, extrusion and filling to form a chain-like plugging layer. The gel particles then contact each other to form ionic bonds, thereby constructing a supramolecular gel with self-repairing ability, which can effectively plug the fracture pores.

3. The supramolecular gel for fractured formations of the present invention forms a three-dimensional network structure under the action of hydrophobic association, can autonomously adapt to harsh and complex fractured formations such as high temperature and high salt, has good compatibility and strong erosion resistance, and can form a high-strength plugging layer in fractured formations.

4. The supramolecular gel plugging agent suitable for fractured formations of the present invention can effectively solve the shortcomings of conventional plugging materials. It has excellent high temperature resistance and shear thixotropy, can adaptively match complex-scale cracks, and fully fill the leakage space to achieve long-term stable plugging. The preparation method is simple and feasible, the production operation is convenient, and the environmental pollution is small.

DETAILED DESCRIPTION

The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other examples improved or modified by ordinary technicians in this field belong to the scope of protection of the present invention.

The raw materials used in the examples are all conventional raw materials and can be obtained commercially; the methods described are all prior art unless otherwise specified.

The polyethylene glycol used in the examples is polyethylene glycol 1500;

The molecular weight of polyhydroxyethyl methacrylate is 650.7, available from Shandong Yinghong Chemical Co., Ltd.

Scleroglucan is available from Hebei Xinhe Biochemical Co., Ltd.

Example 1

A supramolecular gel plugging agent for fractured strata comprises the following raw materials in percentage by mass: 30% copolymerization monomer, 3.5% surfactant, 0.5% initiator, 0.8% cosolvent, 0.25% promoter, 1.5% brine solution, and the balance is water, wherein the total content of each component is 100%.

The copolymerization reaction monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule, wherein the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 7:2:1; the hydrophilic monomer is a combination of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and N-vinyl pyrrolidone, wherein the mass ratio of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and N-vinyl pyrrolidone is 5:3:2; the hydrophobic monomer is a combination of octadecyl methacrylate and lauryl methacrylate, wherein the mass ratio of octadecyl methacrylate and lauryl methacrylate is 7:3; the functional group molecule is a combination of scleroglucan, chitosan and β-cyclodextrin, wherein the mass ratio of scleroglucan, chitosan and β-cyclodextrin is 6:3:1.

The surfactant is a combination of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate, and the mass ratio of sodium dodecylbenzene sulfonate to sodium dodecyl sulfate is 2:3.

The initiator is a combination of azobisisobutylimidazoline hydrochloride and potassium persulfate, and the mass ratio of azobisisobutylimidazoline hydrochloride to potassium persulfate is 2:3.

The co-solvent is a combination of anhydrous sodium sulfate and ammonium chloride in a mass ratio of 1:1.

The accelerator is a combination of triethylenediamine and N,N-dimethyl-p-toluidine, and the mass ratio of triethylenediamine to N,N-dimethyl-p-toluidine is 3:2.

The saline solution is a sodium chloride solution with a concentration of 2.5 mol/L.

The preparation method of the supramolecular gel plugging agent for fractured formations comprises the following steps:

(1) adding the hydrophilic monomer in the copolymerization monomer into water, stirring at a stirring speed of 500 rpm at 25° C. for 25 minutes to obtain a mixed solution A;

(2) adding a hydrophobic monomer in the copolymerization monomer to the mixed solution A, stirring at 25° C. and 500 rpm for 28 minutes to obtain a mixed solution B;

(3) adding functional group molecules and surfactants to mixed solution B, stirring at a temperature of 40° C. and a stirring speed of 550 rpm for 45 minutes to obtain mixed solution C;

(4) adding the initiator and the co-solvent to the mixed solution C, stirring at a stirring temperature of 45° C. and a stirring speed of 550 rpm for 30 minutes until the initiators and the co-solvents are completely dissolved to obtain a mixed solution D;

(5) adding an accelerator and a saline solution to the mixed solution D, stirring the mixture at 50° C. and 500 rpm for 30 minutes to obtain a mixed solution E;

(6) The mixed solution E was placed in a three-necked flask, nitrogen was introduced, and the mixture was vacuumed. The mixture was then allowed to stand at 60°C for 6 hours until the free radicals were fully polymerized to obtain a supramolecular gel. The supramolecular gel was vacuum dried at 70°C for 24 hours and then crushed to obtain a supramolecular gel plugging agent for fractured formations, which was recorded as sample S1.

Example 2

A supramolecular gel plugging agent for fractured strata comprises the following raw materials in percentage by mass: 28% copolymerization monomer, 4.3% surfactant, 0.5% initiator, 0.7% cosolvent, 0.20% promoter, 2.0% brine solution, and the balance is water, wherein the total content of each component is 100%.

The copolymerization reaction monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule, wherein the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 7:2:1; the hydrophilic monomer is a combination of acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and hexadecyl dimethyl allyl ammonium chloride, wherein the mass ratio of acrylic acid, 2-acrylamide-2-methylpropane sulfonic acid and hexadecyl dimethyl allyl ammonium chloride is 5:3:2; the hydrophobic monomer is a combination of octadecyl methacrylate and hexadecyl methacrylate, wherein the mass ratio of octadecyl methacrylate and hexadecyl methacrylate is 7:3; the functional group molecule is a combination of scleroglucan, chitosan and cucurbituril, wherein the mass ratio of scleroglucan, chitosan and cucurbituril is 6:3:1.

The surfactant is a combination of betaine and sodium dodecyl sulfate, and the mass ratio of betaine to sodium dodecyl sulfate is 3:2.

The initiator is a combination of ammonium persulfate and potassium persulfate, and the mass ratio of ammonium persulfate to potassium persulfate is 3:2.

The co-solvent is a combination of anhydrous sodium sulfate and ammonium chloride, and the mass ratio of anhydrous sodium sulfate to ammonium chloride is 2:1.

The accelerator is a combination of triethylenediamine and N,N-dimethyl-p-toluidine, with a mass ratio of 1:1.

The saline solution is a sodium chloride solution with a concentration of 2.5 mol/L.

The preparation method of the supramolecular gel plugging agent for fractured formations is as described in Example 1, and the prepared supramolecular gel plugging agent is recorded as sample S2.

Example 3

A supramolecular gel plugging agent for fractured strata comprises the following raw materials in mass percentage: 26% copolymerization monomer content; 5% surfactant content; 0.5% initiator content; 0.8% cosolvent content; 0.30% promoter content; 2.0% brine solution content, the balance being water, and the total content of each component being 100%.

The copolymerization monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule, wherein the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 7:2:1; the hydrophilic monomer is a combination of polyethylene glycol, 2-acrylamide-2-methylpropane sulfonic acid and 2-vinyl pyridine, wherein the mass ratio of polyethylene glycol, 2-acrylamide-2-methylpropane sulfonic acid and 2-vinyl pyridine is 5:3:2; the hydrophobic monomer is a combination of octadecyl methacrylate and butyl methacrylate, wherein the mass ratio of octadecyl methacrylate and butyl methacrylate is 3:2; the functional group molecule is a combination of scleroglucan, chitosan and sodium alginate, wherein the mass ratio of scleroglucan, chitosan and sodium alginate is 3:1:1.

The surfactant is a combination of sodium dodecyl sulfate and sorbitan fatty acid, and the mass ratio of sodium dodecyl sulfate to sorbitan fatty acid is 4:1.

The initiator is a combination of ammonium persulfate and potassium persulfate, and the mass ratio of ammonium persulfate to potassium persulfate is 2:3.

The co-solvent is a combination of anhydrous calcium sulfate and urea, and the mass ratio of anhydrous calcium sulfate to urea is 2:1.

The accelerator is a combination of triethylenediamine and tetramethylthiourea, with a mass ratio of 1:1.

The saline solution is a sodium chloride solution with a concentration of 2.5 mol/L.

The preparation method of the supramolecular gel plugging agent for fractured formations is as described in Example 1. The prepared supramolecular gel plugging agent is recorded as sample S3.

Example 4

A supramolecular gel plugging agent for fractured strata comprises the following raw materials in percentage by mass: 26% copolymerization monomer, 4.5% surfactant, 0.6% initiator, 0.9% cosolvent, 0.40% promoter, 2.0% brine solution, and the balance is water, wherein the total content of each component is 100%.

The copolymerization monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule, wherein the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 7:2:1; the hydrophilic monomer is a combination of methacrylic acid, sodium acrylate and N-isopropylacrylamide, wherein the mass ratio of methacrylic acid, sodium acrylate and N-isopropylacrylamide is 4:3:3; the hydrophobic monomer is a combination of hexadecyl methacrylate and polyhydroxyethyl methacrylate, wherein the mass ratio of hexadecyl methacrylate and polyhydroxyethyl methacrylate is 4:1; the functional group molecule is a combination of sodium alginate, β-cyclodextrin and calix[6]arene, wherein the mass ratio of sodium alginate, β-cyclodextrin and calix[6]arene is 1:4:1.

The surfactant is a combination of sodium dodecyl sulfate and stearic acid, and the mass ratio of sodium dodecyl sulfate to stearic acid is 3:2.

The initiator is a combination of potassium persulfate and dimethyl azobisisobutyrate, and the mass ratio of potassium persulfate to dimethyl azobisisobutyrate is 4:1.

The co-solvent is a combination of anhydrous calcium sulfate and ammonium chloride, and the mass ratio of anhydrous calcium sulfate to ammonium chloride is 2:1.

The accelerator is a combination of triethylamine and 8-hydroxyquinoline, with a mass ratio of 1:1.

The saline solution is a sodium chloride solution with a concentration of 2.5 mol/L.

The preparation method of the supramolecular gel plugging agent for fractured formations is as described in Example 1. The prepared supramolecular gel plugging agent is recorded as sample S4.

Example 5

A supramolecular gel plugging agent for fractured formations, comprising the following raw materials in percentage by mass:

The content of copolymerization monomer is 24%, the content of surfactant is 5%, the content of initiator is 0.5%, the content of cosolvent is 0.8%, the content of promoter is 0.50%, the content of salt water solution is 2.0%, and the balance is water. The total content of each component is 100%.

The copolymerization monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule, wherein the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 7:2:1; the hydrophilic monomer is a combination of acrylamide, polyethylene glycol and methacrylic acid, wherein the mass ratio of acrylamide, polyethylene glycol and methacrylic acid is 5:3:2; the hydrophobic monomer is a combination of dimethylaminoethyl methacrylate and 4-methylstyrene, wherein the mass ratio of dimethylaminoethyl methacrylate and 4-methylstyrene is 3:2; the functional group molecule is a combination of scleroglucan, sodium alginate and calix[6]arene, wherein the mass ratio of scleroglucan, sodium alginate and calix[6]arene is 1:4:1.

The surfactant is a combination of sodium dodecyl sulfate and stearic acid, and the mass ratio of sodium dodecyl sulfate to stearic acid is 3:2.

The initiator is a combination of cumene hydroperoxide and azobisisobutyl ester, and the mass ratio of cumene hydroperoxide to azobisisobutyl ester is 1:4.

The co-solvent is a combination of anhydrous sodium sulfate and urea, and the mass ratio of anhydrous sodium sulfate to urea is 3:2.

The accelerator is a combination of 1,2-bis(dimethylamino)ethane and ferrocene, and the mass ratio of 1,2-bis(dimethylamino)ethane to ferrocene is 4:1.

The saline solution is a sodium chloride solution with a concentration of 2.5 mol/L.

The preparation method of the supramolecular gel plugging agent for fractured formations is as described in Example 1. The prepared supramolecular gel plugging agent is recorded as sample S5.

Example 6

A supramolecular gel plugging agent for fractured strata comprises the following raw materials in percentage by mass: 28% copolymerization monomer, 4.3% surfactant, 0.5% initiator, 0.7% cosolvent, 0.20% promoter, 2.0% brine solution, and the balance is water, wherein the total content of each component is 100%.

The copolymerization monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule, wherein the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 7:2:1; the hydrophilic monomer is a combination of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride, wherein the mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride is 5:3:2; the hydrophobic monomer is a combination of octadecyl methacrylate and hexadecyl methacrylate, wherein the mass ratio of octadecyl methacrylate and hexadecyl methacrylate is 7:3; the functional group molecule is a combination of chitosan, sodium alginate and β-cyclodextrin, wherein the mass ratio of chitosan, sodium alginate and β-cyclodextrin is 4:3:3.

The surfactant is a combination of betaine and sodium dodecyl sulfate, and the mass ratio of betaine to sodium dodecyl sulfate is 4:1.

The initiator is a combination of ammonium persulfate and potassium persulfate, and the mass ratio of ammonium persulfate to potassium persulfate is 3:2.

The co-solvent is a combination of anhydrous sodium sulfate and ammonium chloride, and the mass ratio of anhydrous sodium sulfate to ammonium chloride is 3:2.

The accelerator is a combination of triethylenediamine and N,N-dimethyl-p-toluidine, and the mass ratio of triethylenediamine to N,N-dimethyl-p-toluidine is 2:1.

The saline solution is a sodium chloride solution with a concentration of 2.5 mol/L.

The preparation method of the supramolecular gel plugging agent for fractured formations is as described in Example 1. The prepared supramolecular gel plugging agent is recorded as sample S6.

Example 7

A supramolecular gel plugging agent for fractured strata comprises the following raw materials in percentage by mass: 28% copolymerization monomer, 4.3% surfactant, 0.5% initiator, 0.7% cosolvent, 0.20% promoter, 2.0% brine solution, and the balance is water, wherein the total content of each component is 100%.

The copolymerization reaction monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule, wherein the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 7:2:1; the hydrophilic monomer is a combination of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride, wherein the mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride is 5:3:2; the hydrophobic monomer is a combination of octadecyl methacrylate and hexadecyl methacrylate, wherein the mass ratio of octadecyl methacrylate and hexadecyl methacrylate is 7:3; the functional group molecule is a combination of β-cyclodextrin, calix[6]arene and cucurbituril, wherein the mass ratio of β-cyclodextrin, calix[6]arene and cucurbituril is 5:3:2.

The surfactant is a combination of betaine and sodium dodecyl sulfate, and the mass ratio of betaine to sodium dodecyl sulfate is 4:3.

The initiator is a combination of ammonium persulfate and potassium persulfate, and the mass ratio of ammonium persulfate to potassium persulfate is 3:2.

The co-solvent is a combination of anhydrous sodium sulfate and ammonium chloride, and the mass ratio of anhydrous sodium sulfate to ammonium chloride is 3:2.

The accelerator is a combination of triethylenediamine and N,N-dimethyl-p-toluidine, and the mass ratio of triethylenediamine to N,N-dimethyl-p-toluidine is 2:1.

The saline solution is a sodium chloride solution with a concentration of 2.5 mol/L.

The preparation method of the supramolecular gel plugging agent for fractured formations is as described in Example 1. The prepared supramolecular gel plugging agent is recorded as sample S7.

Example 8

A supramolecular gel plugging agent for fractured strata comprises the following raw materials in percentage by mass: 28% copolymerization monomer, 4.3% surfactant, 0.5% initiator, 0.7% cosolvent, 0.20% promoter, 2.0% brine solution, and the balance is water, wherein the total content of each component is 100%.

The copolymerization reaction monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule, wherein the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 7:2:1; the hydrophilic monomer is a combination of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride, wherein the mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride is 5:3:2; the hydrophobic monomer is a combination of octadecyl methacrylate and hexadecyl methacrylate, wherein the mass ratio of octadecyl methacrylate and hexadecyl methacrylate is 7:3; the functional group molecule is a combination of chitosan, calix[6]arene and cucurbituril, wherein the mass ratio of β-cyclodextrin, calix[6]arene and cucurbituril is 6:3:1.

The surfactant is a combination of betaine and sodium dodecyl sulfate, and the mass ratio of betaine to sodium dodecyl sulfate is 4:3.

The initiator is a combination of ammonium persulfate and potassium persulfate, and the mass ratio of ammonium persulfate to potassium persulfate is 3:2.

The co-solvent is a combination of anhydrous sodium sulfate and ammonium chloride, and the mass ratio of anhydrous sodium sulfate to ammonium chloride is 3:2.

The accelerator is a combination of triethylenediamine and N,N-dimethyl-p-toluidine, and the mass ratio of triethylenediamine to N,N-dimethyl-p-toluidine is 2:1.

The saline solution is a sodium chloride solution with a concentration of 2.5 mol/L.

The preparation method of the supramolecular gel plugging agent for fractured formations is as described in Example 1. The prepared supramolecular gel plugging agent is recorded as sample S8.

Example 9

A supramolecular gel plugging agent for fractured strata comprises the following raw materials in percentage by mass: 28% copolymerization monomer, 4.3% surfactant, 0.5% initiator, 0.7% cosolvent, 0.20% promoter, 2.0% brine solution, and the balance is water, wherein the total content of each component is 100%.

The copolymerization monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule, wherein the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 7:2:1; the hydrophilic monomer is a combination of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride, wherein the mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride is 5:3:2; the hydrophobic monomer is a combination of octadecyl methacrylate and hexadecyl methacrylate, wherein the mass ratio of octadecyl methacrylate and hexadecyl methacrylate is 7:3; the functional group molecule is a combination of sodium alginate, calix[6]arene and cucurbituril, wherein the mass ratio of sodium alginate, calix[6]arene and cucurbituril is 2:3:5.

The surfactant is a combination of betaine and sodium dodecyl sulfate, and the mass ratio of betaine to sodium dodecyl sulfate is 4:3.

The initiator is a combination of ammonium persulfate and potassium persulfate, and the mass ratio of ammonium persulfate to potassium persulfate is 3:2.

The co-solvent is a combination of anhydrous sodium sulfate and ammonium chloride, and the mass ratio of anhydrous sodium sulfate to ammonium chloride is 3:2.

The accelerator is a combination of triethylenediamine and N,N-dimethyl-p-toluidine, and the mass ratio of triethylenediamine to N,N-dimethyl-p-toluidine is 2:1.

The saline solution is a sodium chloride solution with a concentration of 2.5 mol/L.

The preparation method of the supramolecular gel plugging agent for fractured formations is as described in Example 1. The prepared supramolecular gel plugging agent is recorded as sample S9.

Example 10

A supramolecular gel plugging agent for fractured strata comprises the following raw materials in percentage by mass: 28% copolymerization monomer, 4.3% surfactant, 0.5% initiator, 0.7% cosolvent, 0.20% promoter, 2.0% brine solution, and the balance is water, wherein the total content of each component is 100%.

The copolymerization monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule, wherein the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 7:2:1; the hydrophilic monomer is a combination of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride, wherein the mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride is 5:3:2; the hydrophobic monomer is a combination of octadecyl methacrylate and hexadecyl methacrylate, wherein the mass ratio of octadecyl methacrylate and hexadecyl methacrylate is 7:3; the functional group molecule is a combination of chitosan, β-cyclodextrin and calix[6]arene, wherein the mass ratio of chitosan, β-cyclodextrin and calix[6]arene is 7:2:1.

The surfactant is a combination of betaine and sodium dodecyl sulfate, and the mass ratio of betaine to sodium dodecyl sulfate is 4:3.

The initiator is a combination of ammonium persulfate and potassium persulfate, and the mass ratio of ammonium persulfate to potassium persulfate is 3:2.

The co-solvent is a combination of anhydrous sodium sulfate and ammonium chloride, and the mass ratio of anhydrous sodium sulfate to ammonium chloride is 3:2.

The accelerator is a combination of triethylenediamine and N,N-dimethyl-p-toluidine, and the mass ratio of triethylenediamine to N,N-dimethyl-p-toluidine is 2:1.

The saline solution is a sodium chloride solution with a concentration of 2.5 mol/L.

The preparation method of the supramolecular gel plugging agent for fractured formations is as described in Example 1. The prepared supramolecular gel plugging agent is recorded as sample S10.

Comparative Example 1

A supramolecular gel plugging agent for fractured formations, the raw material composition is as described in Example 1, except that: no functional group molecules are added.

The specific raw material composition is as follows: the copolymerization monomer content is 30% (the mass ratio of the hydrophilic monomer to the hydrophobic monomer is 7:2); the surfactant content is 3.5%; the initiator content is 0.5%; the co-solvent content is 0.8%; the promoter content is 0.25%; the saline solution content is 1.5%, and the balance is water, and the total content of each component is 100%; the types of the above components are as described in Example 1.

The preparation method of the supramolecular gel plugging agent is as described in Example 1, and the obtained product is recorded as D1.

Comparative Example 2

A supramolecular gel plugging agent for fractured formations, the raw material composition of which is as described in Example 1, except that no surfactant is added.

The specific raw material composition is as follows: the copolymerization monomer content is 30%; the initiator content is 0.5%; the co-solvent content is 0.8%; the promoter content is 0.25%; the salt water content is 1.5%, and the balance is water, and the total content of each component is 100%; the types of the above components are as described in Example 1.

The preparation method of the supramolecular gel plugging agent is as described in Example 1, and the obtained product is recorded as D2.

Comparative Example 3

A supramolecular gel plugging agent for fractured formations, the raw material composition is as described in Example 1, except that no initiator is added.

The specific raw material composition is as follows: the copolymerization monomer content is 30%; the surfactant content is 3.5%; the cosolvent content is 0.8%; the promoter content is 0.25%; the salt solution content is 1.5%, and the balance is water, and the total content of each component is 100%; the types of the above components are as described in Example 1.

The preparation method of the supramolecular gel plugging agent is as described in Example 1, and the obtained product is recorded as D3.

Comparative Example 4

A supramolecular gel plugging agent for fractured formations, the raw material composition is as described in Example 1, except that no co-solvent is added.

The specific raw material composition is as follows: the copolymerization monomer content is 30%; the surfactant content is 3.5%; the initiator content is 0.5%; the promoter content is 0.25%; the salt water content is 1.5%, and the balance is water, and the total content of each component is 100%; the types of the above components are as described in Example 1.

The preparation method of the supramolecular gel plugging agent is as described in Example 1, and the obtained product is recorded as D4.

Comparative Example 5

A supramolecular gel plugging agent for fractured formations, the raw material composition is as described in Example 1, except that no accelerant is added.

The specific raw material composition is as follows: the copolymerization monomer content is 30%; the surfactant content is 3.5%; the initiator content is 0.5%; the cosolvent content is 0.8%; the saline solution content is 1.5%, and the balance is water, and the total content of each component is 100%; the types of the above components are as described in Example 1.

The preparation method of the supramolecular gel plugging agent is as described in Example 1, and the obtained product is recorded as D5.

Comparative Example 6

A supramolecular gel plugging agent for fractured formations, the raw material composition is as described in Example 1, except that the copolymerization reaction monomer content is 15%.

The specific raw material composition is as follows: the copolymerization monomer content is 15%; the initiator content is 0.5%; the co-solvent content is 0.8%; the promoter content is 0.25%; the salt water content is 1.5%, and the balance is water, and the total content of each component is 100%; the types of the above components are as described in Example 1.

The preparation method of the supramolecular gel plugging agent is as described in Example 1, and the obtained product is recorded as D6.

Comparative Example 7

A supramolecular gel plugging agent for fractured formations, the raw material composition is as described in Example 1, except that: the content of copolymerization monomer is 10%; the types of the above components are as described in Example 1.

The specific raw material composition is as follows: the copolymerization monomer content is 10%; the initiator content is 0.5%; the co-solvent content is 0.8%; the promoter content is 0.25%; the salt water content is 1.5%, and the balance is water. The total content of each component is 100%.

The preparation method of the supramolecular gel plugging agent is as described in Example 1, and the obtained product is recorded as D7.

Comparative Example 8

A supramolecular gel plugging agent for fractured formations, the raw material composition of which is as described in Example 1, except that the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 5:1:1.

The preparation method of the supramolecular gel plugging agent is as described in Example 1, and the obtained product is recorded as D8.

Comparative Example 9

A supramolecular gel plugging agent for fractured formations, the raw material composition is as described in Example 1, except that the mass ratio of the hydrophilic monomer, the hydrophobic monomer and the functional group molecule is 9:1:1.

The preparation method of the supramolecular gel plugging agent is as described in Example 1, and the obtained product is recorded as D9.

Test example

The supramolecular gel plugging agents prepared in the above examples and comparative examples were tested for rheological properties, compression resistance, and high temperature and high pressure plugging performance.

Test 1. Rheological properties test of supramolecular gel plugging agent

The rheological properties of the supramolecular gel were tested using a HAAKE MARS 60 rheometer, with a conical rotor model of C35 1°/Ti (rotor cone angle of 1°, diameter of 35 mm), and a gap of 0.053 mm between the rotor and the sample stage during the test. During the experiment, the supramolecular gel plugging agent was cut into circular sample slices with a diameter of 30 mm and a thickness of 10 mm using a vernier caliper, wherein the test conditions for the storage modulus (G') and the loss modulus (G") were 1.0% constant strain, the oscillation scanning frequency was set to 1 Hz, and the angular frequency range was set to 0.01-100 rad·s ^-1 . The temperature of the test sample was balanced for at least 30 minutes, and the temperature error was controlled at ±0.1°C. During the experiment, a solvent trap was used to reduce water evaporation.

The evaluation standard of the rheological property of the supramolecular gel plugging agent is shown in Table 1. Among them, the ratio of the storage modulus to the loss modulus is defined as β, which represents the elastic strength; the ratio of the loss modulus to the storage modulus is defined as δ, which represents the viscous strength; the rheological property results of the supramolecular gel plugging agents prepared in the above embodiments and comparative examples are shown in Table 2.

Test 2. Compression resistance test of supramolecular gel plugging agent

The supramolecular gel plugging agent was made into a cylinder with a bottom diameter of 20mm and a height of 10mm. The gel compression mechanical properties were tested using an electronic universal testing machine. The compression speed was set to 3mm/min, and the stress-strain value of the supramolecular gel plugging agent sample was recorded when it was compressed. The compression rate ω refers to the ratio of the height of the compressed gel to the original height of the gel before compression; the compression stress τ refers to the value obtained by dividing the compression load applied to the sample by the original cross-sectional area of the sample during the compression test, which can be directly measured.

The evaluation criteria for the compression resistance of the supramolecular gel plugging agent are shown in Table 3; the compression resistance results of the supramolecular gel plugging agents prepared in the above embodiments and comparative examples are shown in Table 4.

Test 3. High temperature and high pressure plugging performance test of supramolecular gel plugging agent

The pressure-bearing plugging performance of supramolecular gel plugging agent on cracks was studied using a high-temperature and high-pressure fracture physical simulation device. The simulated fracture core is made of steel and has a columnar appearance. The crack runs through the longitudinal section of the steel column. The length of the crack is 30 cm, the height is 3 cm, and the width is 3, 5, 7, and 9 mm respectively.

The steps of the high-temperature and high-pressure plugging test are as follows: (a) adjust the temperature of the heating box to the simulated formation temperature of 160°C as required; (b) place a steel fracture core with the required fracture width into the core holder and add a confining pressure of 16 MPa; (c) inject simulated drilling fluid into the fracture core at an injection rate of 5.0 mL/min until saturation; (d) inject the supramolecular gel solution (i.e., mixed solution E) into the fracture core at an injection rate of 5.0 mL/min until the gel solution is completely produced at the fracture outlet; (e) seal the fracture core model and let it stand for 2 hours until the supramolecular gel solution reacts; (f) reversely inject simulated drilling fluid into the fracture core at an injection rate of 5.0 mL/min, and use data software to record the injection pressure changes in real time. The highest pressure reached when the drilling fluid leaks from the outlet of the fracture model is the pressure-bearing plugging strength of the supramolecular gel plugging agent on the fracture.

The high temperature and high pressure plugging performance results of the supramolecular gel plugging agents prepared in the above embodiments and comparative examples are shown in Table 5.

Test 4. Salt resistance and temperature resistance test of supramolecular gel plugging agent

The salt resistance test method of the supramolecular gel plugging agent is as follows: a sodium chloride solution with a concentration of 200000 mg·L ^-1 and a calcium chloride solution with a concentration of 10000 mg·L ^-1 are compounded and replaced with water to simulate the mineralization of formation water to prepare a supramolecular gel plugging agent, and the supramolecular gel plugging agent is placed in a high-temperature oven at a temperature of 160°C to observe and record the gelation time, and after gelation, the storage modulus is tested using a Haake rheometer. The supramolecular gel prepared by the method of the above-mentioned embodiment 1-2 is tested for salt resistance according to the salt resistance test method, and the test results are shown in Table 6.

The method for testing the temperature resistance of the supramolecular gel plugging agent is as follows: the supramolecular gel sample prepared in Example 1 is placed in a steel fracture core with a fracture width of 3 mm, and is placed in a constant temperature aging furnace at 150°C, 160°C, 170°C and 180°C for 72 hours, and then a high temperature and high pressure plugging performance test is performed to observe its temperature resistance. The temperature resistance results of the above Example 1 under different temperature conditions are shown in Table 7.

Table 1 Evaluation criteria for supramolecular gel rheology

Table 2 Rheological properties of supramolecular gel plugging agents prepared in Examples and Comparative Examples

Table 3 Evaluation criteria for the compression resistance of supramolecular gel plugging agents

Compression rateω/% Compression stress τ/N Compressive strength ω≥90 τ ≥ 400 powerful 80≤ω＜90 300≤τ＜400 medium ω＜80 τ＜300 weak

Table 4 Compression resistance results of supramolecular gel plugging agents prepared in Examples and Comparative Examples

Table 5 High temperature and high pressure plugging performance results of supramolecular gels prepared in Examples and Comparative Examples

Table 6 Test results of salt resistance of supramolecular gel plugging agent

Table 7 Test results of temperature resistance of supramolecular gel plugging agent under different temperature conditions

Through different performance evaluation tests on the supramolecular gel plugging agents prepared in various embodiments and comparative examples, it is found that the addition of functionalized group molecules to the supramolecular gel raw materials is conducive to the construction of the three-dimensional network structure of the supramolecular gel, and the addition of surfactants also promotes the hydrophobic association interaction between the hydrophilic monomer and the hydrophobic monomer. At the same time, the introduction of multiple hydrogen bonds and host-guest molecules through supramolecular structure design can increase the mutual entanglement strength between supramolecular gels, which can effectively improve the pressure-bearing plugging capacity and compression resistance of the supramolecular gel plugging agent in formations with different fracture widths. The pressure-bearing capacity is above 14MPa, the compression rate is above 91%, and the compression resistance is strong; and the supramolecular gel plugging agent of the present invention has high temperature resistance and salt resistance. The storage modulus G' of the supramolecular gel plugging agent prepared by the present invention is above 4000Pa, which can meet better use conditions.

Claims (9)

1. The supermolecular gel plugging agent for the fractured stratum is characterized by comprising the following raw materials in percentage by mass: 18-45% of comonomer, 0.5-6.0% of surfactant, 0.1-2.0% of initiator, 0.1-2.0% of cosolvent, 0.05-0.5% of accelerator, 0.5-5% of saline solution and the balance of water; the copolymerization monomer is a combination of a hydrophilic monomer, a hydrophobic monomer and a functional group molecule; the mass ratio of the hydrophilic monomer to the hydrophobic monomer to the functional group molecules in the copolymerization monomer is 6-8:1-3:1;

the hydrophilic monomer is a combination of more than three of acrylamide, acrylic acid, methacrylic acid, sodium acrylate, polyethylene glycol, N-isopropyl acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, cetyl dimethyl allyl ammonium chloride, N-vinyl pyrrolidone, 2-vinyl pyridine and N-hydroxyethyl acrylamide;

the hydrophobic monomer is a combination of two or more than three of octadecyl methacrylate, methyl methacrylate, butyl methacrylate, hexadecyl methacrylate, polyhydroxyethyl methacrylate, dimethylaminoethyl methacrylate, 2-ethyl methacrylate, beta-hydroxyethyl methacrylate, lauryl methacrylate, 4-trifluoro methyl ethylene carbonate and 4-methyl styrene;

The functional group molecules are the combination of more than three of scleroglucan, chitosan, sodium alginate, beta-cyclodextrin, calix [6] arene and cucurbituril;

the surfactant is one or a combination of more than two of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, dodecylphenol polyoxyethylene ether, stearic acid, fatty acid sorbitan, betaine and polysorbate;

the cosolvent is sulfate and/or a nitrogen-containing compound, wherein the sulfate is anhydrous sodium sulfate or anhydrous calcium sulfate, and the nitrogen-containing compound is urea or ammonium chloride;

the accelerator is one or more than two of 1, 2-bis (dimethylamino) ethane, triethylene diamine, ferric trichloride, tetramethylthiourea, vanadium acetylacetonate, acetylacetone, N-dimethyl-p-toluidine, triethylamine, tetrahydroquinoline, 8-hydroxyquinoline and ferrocene;

the preparation method of the supermolecular gel plugging agent for the fractured stratum comprises the following steps:

(1) Adding hydrophilic monomers in the copolymerization monomers into water, and uniformly stirring to obtain a mixed solution A;

(2) Adding a hydrophobic monomer in the copolymerization monomer into the mixed solution A, and uniformly stirring to obtain a mixed solution B;

(3) Adding functional group molecules and a surfactant into the mixed solution B, and uniformly stirring to obtain a mixed solution C;

(4) Adding an initiator and a cosolvent into the mixed solution C, and stirring until the initiator and the cosolvent are completely dissolved to prepare a mixed solution D;

(5) Adding an accelerator and a saline solution into the mixed solution D, and uniformly stirring to obtain a mixed solution E;

(6) Deoxidizing and degassing the mixed solution E, and standing for reaction to obtain supermolecule gel; and drying and crushing the supermolecular gel to obtain the supermolecular gel plugging agent for the fractured stratum.

2. The supramolecular gel plugging agent for fractured formations of claim 1, comprising the following raw materials in mass percent: 24-35% of comonomer, 3-5% of surfactant, 0.4-1% of initiator, 0.5-1% of cosolvent, 0.2-0.5% of accelerator, 1-3% of saline solution and the balance of water.

3. The supramolecular gel plugging agent for fractured formations of claim 1, wherein the mass ratio of hydrophilic monomers, hydrophobic monomers to functionalized group molecules in the co-reactive monomers is 7:2:1.

4. The supramolecular gel plugging agent for fractured formations of claim 1, wherein the initiator is one or a combination of two or more of diisopropyl peroxydicarbonate, t-butyl peroxybenzoate, cumene hydroperoxide, potassium persulfate, ammonium persulfate, azobisisobutyrate, dimethyl azobisisobutyrate, azobisiso Ding Mi, hydrochloride.

5. The supramolecular gel plugging agent for fractured formations of claim 1, wherein the co-solvent is a combination of sulfate and nitrogen-containing compounds, wherein the mass ratio of sulfate to nitrogen-containing compounds is 1-2:1;

the accelerator is a combination of triethylene diamine and N, N-dimethyl-p-toluidine;

the saline solution is sodium chloride water solution and/or potassium chloride water solution; the concentration of the saline solution is 0.5-5mol/L.

6. A method of preparing the supramolecular gel plugging agent for fractured formations of any of claims 1-5 comprising the steps of:

(1) Adding hydrophilic monomers in the copolymerization monomers into water, and uniformly stirring to obtain a mixed solution A;

(2) Adding a hydrophobic monomer in the copolymerization monomer into the mixed solution A, and uniformly stirring to obtain a mixed solution B;

(3) Adding functional group molecules and a surfactant into the mixed solution B, and uniformly stirring to obtain a mixed solution C;

(4) Adding an initiator and a cosolvent into the mixed solution C, and stirring until the initiator and the cosolvent are completely dissolved to prepare a mixed solution D;

(5) Adding an accelerator and a saline solution into the mixed solution D, and uniformly stirring to obtain a mixed solution E;

(6) Deoxidizing and degassing the mixed solution E, and standing for reaction to obtain supermolecule gel; and drying and crushing the supermolecular gel to obtain the supermolecular gel plugging agent for the fractured stratum.

7. The method for preparing a supramolecular gel plugging agent for fractured formations according to claim 6, wherein in step (1), the stirring temperature is 20-45 ℃; the stirring speed is 300-1000 rpm; stirring for 10-40 min;

in the step (2), the stirring temperature is 20-50 ℃; the stirring speed is 200-800 rpm; stirring for 5-30 min;

in the step (3), the stirring temperature is 30-50 ℃; stirring speed is 400-1000 rpm; stirring for 30-60 min;

in the step (4), the stirring temperature is 30-70 ℃; stirring at 400-800 rpm; stirring for 20-40 min;

in the step (5), the stirring temperature is 30-70 ℃; stirring at 400-800 rpm; stirring for 20-40 min;

in the step (6), the deoxidization and the deaeration are carried out by introducing nitrogen and vacuum pumping; the temperature of the standing reaction is 50-80 ℃; standing for 5-9 hours; the drying is carried out for 20-30 hours under the condition that the vacuum degree is 0.08-0.1MPa and the temperature is 55-80 ℃.

8. The method for preparing a supramolecular gel plugging agent for fractured formations according to claim 6, wherein in step (1), the stirring temperature is 25-30 ℃; stirring at 400-600 rpm; stirring for 20-30 minutes;

In the step (2), the stirring temperature is 23-28 ℃; the stirring speed is 450-580 r/min; stirring for 24-28 min;

in the step (3), the stirring temperature is 35-40 ℃; the stirring speed is 500-700 rpm; stirring for 40-50 min;

in the step (4), the stirring temperature is 40-50 ℃; the stirring speed is 500-600 rpm; stirring for 25-35 min;

in the step (5), the stirring temperature is 40-60 ℃; the stirring speed is 450-550 rpm; stirring for 25-30 min;

in the step (6), the temperature of the standing reaction is 60-65 ℃; standing for 6-7 hours; the drying is carried out for 24-26 hours under the condition that the vacuum degree is 0.08-0.1MPa and the temperature is 70-75 ℃.

9. Use of the supramolecular gel plugging agent for fractured formations of any of claims 1-5 in fractured formation plugging; the specific application method is as follows: the plugging material is used for plugging drilling fluid, the addition amount of the plugging material is 2% -5% of the mass of the drilling fluid, and the plugging material is injected in a mode of injection while drilling.