A temporary plugging agent for a velvet capsule

Abstract

The present application relates to a kind of temporary plugging agent of velvet capsule, belong to oil and gas field chemical technical field.The temporary plugging agent of velvet capsule of the present application includes basic compound and following mass fraction of each component: water 100 parts, capsule layer agent 1.5~2.5 parts, velvet agent 0.8~1.5 parts, nucleating agent 0.2~0.8 parts, film forming agent 0.4~1 part, high temperature stabilizer 0.8~1.5 parts.The temporary plugging agent of the present application is temporary plugging agent of velvet capsule, with good high temperature stability, due to its unique velvet capsule structure, the pressure capacity under 150 DEG C can reach more than 19.8MPa, with excellent sealing performance, can meet the requirement of carbonate rock low pressure gas layer plugging.The solid content of the temporary plugging agent of the present application is low, the gel breaking rate can reach more than 98.85%, the permeability recovery rate to seamless core can reach more than 87.56%, and the reservoir protection performance is excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of velvet capsule temporary plugging agent, belong to oil and gas field chemical technology field. BACKGROUND

[0002] Acid fracturing stimulation technology becomes the key technology of carbonate reservoir development and production, acid fracturing stimulation technology is to use ground high-pressure pump, by wellbore high viscosity liquid injection into the oil layer, form high pressure at the bottom of the oil layer, when the pressure breaks through the rock fracture pressure of oil layer, the oil layer produces crack;Continue to squeeze and inject into the oil layer, the crack will continue to expand inside the oil layer technology. At present, carbonate reservoirs generally use temporary plugging agent acid fracturing stimulation technology, in which the temporary plugging agent preferentially seals natural cracks and artificial acid etching cracks, and the subsequent acid liquid opens new cracks under pressure, thereby connecting the distal reservoirs, realizing the exploitation of remaining reserves and improving the recovery of oil reservoirs.

[0003] Carbonate reservoirs have the characteristics of large reservoir depth, high temperature and high pressure, the reservoir depth can reach more than 6000m, the reservoir temperature is 130-150℃, the oil and gas storage space is complex, the solution cave and the crack coexist, the reservoir permeability difference is large, and the heterogeneity is serious. Carbonate temporary plugging agent is mainly divided into solid phase temporary plugging agent and solid-free temporary plugging agent. The degradation of solid phase temporary plugging agent is insufficient, part of it will remain in the seepage channel after injection into the formation, which will damage the productivity. Conventional solid-free temporary plugging agent mainly includes foam temporary plugging agent, ultra-fine fiber temporary plugging agent, etc., which has little damage to the reservoir after degradation, and is a promising temporary plugging agent type at present. Conventional foam temporary plugging agent cannot meet the requirements of carbonate reservoir acid fracturing reconstruction due to its low plugging capacity, and has not been applied in acidizing and fracturing operations. The pressure-bearing capacity of ultra-fine fiber temporary plugging agent is limited, and the high molecular fiber is easy to entangle, so the transportation distance in the formation is limited, which cannot achieve the purpose of temporary plugging and turning in the deep reservoir. Velvet capsule temporary plugging agent is a solid-free temporary plugging agent developed in recent years, which includes velvet agent, nucleating agent, film-forming agent and capsule layer agent, and has the advantages of low reservoir damage rate and excellent plugging capacity.

[0004] CN105820803A discloses a well repair fluid, which comprises by mass percentage: fluff agent 0.4-0.8%, layering agent 1.0-2.0%, nucleating agent 0.1-0.3%, film forming agent 0.2-0.5%, oxygen scavenger 0.5-1.0%, bactericide 0.1-0.2%, potassium chloride 3.0-5.0%, high-temperature stabilizer 0.5-1.0%, hydrogen sulfide scavenger 0.5-1.0%, corrosion inhibitor 0.1-0.2%, water lock inhibitor 0.5-1.0%, cleanup agent 0.5-1.0%, and water 86-93%. The well repair fluid has high stability, good sand carrying performance, strong cleanup ability, and small formation damage, and can effectively temporarily block the formation. However, the well repair fluid has poor temperature resistance. CN104694111A discloses a low-temperature fresh water-based fracturing diverting fluid for coal bed methane, which is prepared from fresh water, fluff agent, nucleating agent, film forming agent, capsule layering agent, inhibitor, potassium chloride, and PAC. The fluff agent is prepared from xanthan gum and polyvinylpyrrolidone. The nucleating agent is prepared from dodecyl dimethyl amine oxide and sodium alpha-alkenyl sulfonate. The film forming agent is prepared from triethanolamine, ethanol, and dodecanol. The capsule layering agent is prepared from carboxymethyl starch and polyanionic cellulose. In the low-temperature fresh water-based fracturing diverting fluid for coal bed methane, the fluff agent accounts for 0.2-0.5 g per 100 g of water, the nucleating agent accounts for 0.05-0.1 g per 100 g of water, the film forming agent accounts for 0.1-0.3 g per 100 g of water, the capsule layering agent accounts for 1.5-1.7 g per 100 g of water, the nucleating agent accounts for 0.03-0.05 g per 100 g of water, the inhibitor accounts for 0.1-0.15 g per 100 g of water, the potassium chloride accounts for 2-3 g per 100 g of water, and the PAC accounts for 0.3 g per 100 g of water. The fracturing diverting fluid has a density of 0.85-1.00 g / cm 3 , a pH value of 7-9, a plastic viscosity of 45-60 mPa·s, a static loss amount of ≤10 mL / 30 min, a dynamic loss amount of ≤10 mL / 30 min, and a core permeability recovery value of ≥85%, and is suitable for coal bed methane formation completion in the Qinshui area. However, the low-temperature fresh water-based fracturing diverting fluid has poor temperature resistance. SUMMARY

[0005] The present application aims to provide a fluff capsule temporary plugging agent, which can solve the problem of poor heat resistance of the current fluff capsule temporary plugging agent.

[0006] To achieve the above-mentioned purpose, the technical scheme of the fluff capsule temporary plugging agent of the present application is as follows:

[0007] The temporary plugging agent comprises an alkaline compound and the following components in mass fraction: 100 parts of water, 1.5-2.5 parts of a capsule layer agent, 0.8-1.5 parts of a fluff agent, 0.2-0.8 parts of a nucleating agent, 0.4-1 part of a film forming agent, and 0.8-1.5 parts of a high-temperature stabilizer.

[0008] The temporary plugging agent is a fluff capsule temporary plugging agent, has good high-temperature stability, has a pressure bearing capacity of more than 19.8 MPa at 150 DEG C due to the unique fluff capsule structure, has excellent plugging performance, and can meet the plugging requirements of low-pressure gas layers of carbonate rocks.

[0009] The structure of the fluff capsule temporary plugging agent is shown in the figure. Figure 1 The temporary plugging agent comprises a gas core 1, a gas-liquid surface tension reducing film 2, a high-viscosity water layer 3, a high-viscosity water layer fixing film 4, a water solubility improving film 5, and a polymer high-molecular and surfactant concentration transition layer 6. The gas core 1 is a wrapped gas. The gas-liquid surface tension reducing film 2 is formed by the close arrangement of the oil-wet groups of the nucleating agent in the high-viscosity water layer 3 to reduce the gas-liquid surface tension. The high-viscosity water layer 3 is formed by the hydration of the water-wet groups of the nucleating agent on the inner and outer sides and the association of the water-wet groups with the film forming agent and the fluff agent, and has a viscosity far higher than that of the liquid phase. The high-viscosity water layer fixing film 4 is formed by the close arrangement of the oil-wet groups of the nucleating agent on the outer side of the high-viscosity water layer 3 to maintain the high viscosity of the high-viscosity water layer 3. The water solubility improving film 5 is formed by the close arrangement of the water-wet groups of the nucleating agent outward, so that the fluff capsule has good water solubility. The polymer high-molecular and surfactant concentration transition layer 6 is a loose layer without fixed thickness formed by the molecular attraction between the film forming agent, the fluff agent and the nucleating agent on the outer side of the water solubility improving film 5 and the molecules of the water solubility improving film 5. The formation mechanism is as follows: the attraction force is weaker with the greater distance, so that the concentration of the polymer high-molecular (film forming agent) and the surfactant gradually decreases from the outer side of the film to the liquid phase.

[0010] The alkaline compound is used for adjusting the pH of the temporary plugging agent and improving the stability of the components in the temporary plugging agent, so that the stable temporary plugging agent is more easily formed. Preferably, the alkaline compound is an alkali metal hydroxide. For example, the alkaline compound is sodium hydroxide or potassium hydroxide.

[0011] Preferably, the mass fraction of the alkaline compound is 1.5-2.5 parts.

[0012] Preferably, the capsule layer agent is a carboxymethyl cellulose salt and / or a carboxymethyl starch salt. Preferably, the carboxymethyl cellulose salt is an alkali metal carboxymethyl cellulose salt; the carboxymethyl starch salt is an alkali metal carboxymethyl starch salt. For example, the capsule layer agent is sodium carboxymethyl cellulose and / or sodium carboxymethyl starch. Sodium carboxymethyl cellulose is an anionic polymer compound, which is a white fibrous or granular powder, odorless, tasteless, hygroscopic, and easily dispersed in water to form a transparent colloidal solution, capable of effectively increasing the thickness of the velvet capsule wall, and the capsule layer agent binds a large number of water molecules, tightly wrapping the gas core outside, preventing the gas in the gas core from escaping, and enhancing the strength of the velvet capsule.

[0013] Preferably, the velvet agent is a heat-resistant starch. As a velvet agent, heat-resistant starch can increase the shear force and viscosity of the velvet capsule temporary plugging agent, and prevent the velvet capsule from moving upward and causing system instability.

[0014] In the present application, heat-resistant starch can be commercially available or self-prepared. For example, commercially available heat-resistant starch suitable for the present application includes high-temperature resistant pre-gelatinized starch, carboxymethyl starch, etc. In order to reduce costs and ensure the stability of raw material supply, preferably, the heat-resistant starch is prepared by a method comprising the following steps: adjusting the pH of a dispersion mainly composed of starch and water to neutral to obtain a pre-reaction solution, then performing a first mixing reaction of the pre-reaction solution and a cross-linking agent at not less than 40℃ for not less than 4h, then performing a second mixing reaction of the system after the first mixing reaction and an esterification agent at not less than 40℃ for not less than 4h, and finally drying and crushing the system after the second mixing reaction to obtain the heat-resistant starch. The purpose of adjusting the pH of the dispersion mainly composed of starch and water to neutral is to provide conditions for subsequent mixing reactions. The purpose of the first mixing reaction is to react the cross-linking agent with the starch. The purpose of the second mixing reaction is to perform esterification modification.

[0015] Preferably, a pH adjuster is used to adjust the pH of the dispersion mainly composed of starch and water to neutral. For example, a sodium hydroxide solution with a mass fraction of 4-6% is used to adjust the pH of the dispersion mainly composed of starch and water to neutral.

[0016] Preferably, the cross-linking agent is trimetaphosphate, phosphorus oxychloride, pyrophosphate, or tripolyphosphate. Preferably, the trimetaphosphate is water-soluble trimetaphosphate; the pyrophosphate is water-soluble pyrophosphate; the tripolyphosphate is water-soluble tripolyphosphate. For example, the trimetaphosphate is sodium trimetaphosphate or potassium trimetaphosphate; the pyrophosphate is sodium pyrophosphate or potassium pyrophosphate; the tripolyphosphate is sodium tripolyphosphate or potassium tripolyphosphate.

[0017] Preferably, the esterification agent is an acid anhydride compound. For example, the esterification agent is acetic anhydride, propionic anhydride, or butyric anhydride.

[0018] Preferably, the heat-resistant starch has a particle size of no less than 40 mesh.

[0019] Preferably, the starch is cassava starch, corn starch and wheat starch.

[0020] Preferably, the mass ratio of the starch, the cross-linking agent and the esterifying agent is (90-100):(1.5-2.0):(4-5). If the amount of the cross-linking agent is too much, the product will contain more impurities, resulting in the decrease of the heat-resistant starch in temperature resistance. If the amount of the cross-linking agent is too little, the degree of substitution of the phosphoric acid group will be low, resulting in the decrease of the heat-resistant starch in temperature resistance. If the amount of the esterifying agent is too much, the purity of the heat-resistant starch will be low, resulting in the decrease of the heat-resistant starch in temperature resistance. If the amount of the esterifying agent is too little, the degree of substitution of the esterifying group will be low, resulting in the decrease of the heat-resistant starch in temperature resistance.

[0021] Preferably, the mass ratio of the starch, the cross-linking agent, the esterifying agent and water is (90-100):(1.5-2.0):(4-5):(195-210).

[0022] Preferably, the nucleating agent is a surfactant. Preferably, the nucleating agent is an anionic surfactant and / or a non-ionic surfactant. The nucleating agent can reduce the gas-liquid surface tension, so that the gas is more easily dissolved in the water phase to form the gas nucleus of the cell center.

[0023] Preferably, the anionic surfactant is an alkyl sulfonate and / or an alkyl benzene sulfonate. Preferably, the anionic surfactant is C 10 -C 16 alkyl sulfonate and / or C 10 -C 16 alkyl benzene sulfonate. For example, the anionic surfactant is one or any combination of sodium dodecyl sulfonate, sodium tridecyl sulfonate, sodium tetradecyl sulfonate, sodium pentadecyl sulfonate, sodium hexadecyl sulfonate, potassium dodecyl sulfonate, potassium tridecyl sulfonate, potassium tetradecyl sulfonate, potassium pentadecyl sulfonate, potassium hexadecyl sulfonate, sodium dodecyl benzene sulfonate, sodium tridecyl benzene sulfonate, sodium tetradecyl benzene sulfonate, sodium pentadecyl benzene sulfonate, sodium hexadecyl benzene sulfonate, potassium dodecyl benzene sulfonate, potassium tridecyl benzene sulfonate, potassium tetradecyl benzene sulfonate, potassium pentadecyl benzene sulfonate, potassium hexadecyl benzene sulfonate.

[0024] Preferably, the non-ionic surfactant is an alkyl acyl alcohol amine. Preferably, the non-ionic surfactant is C 10 -C 16 alkyl acyl alcohol amine. Preferably, the non-ionic surfactant is dodecyl isopropyl alcohol amine, dodecyl diethanol amide.

[0025] Preferably, the anionic surfactant comprises dodecyl sulfonate and dodecyl benzene sulfonate. Preferably, the mass ratio of the dodecyl sulfonate and the dodecyl benzene sulfonate is 1:(0.8-1.2). Preferably, the dodecyl sulfonate is sodium dodecyl sulfonate and / or potassium dodecyl sulfonate. Preferably, the dodecyl benzene sulfonate is sodium dodecyl benzene sulfonate and / or potassium dodecyl benzene sulfonate. The nucleation ability of the mixture of dodecyl sulfonate and dodecyl benzene sulfonate is stronger, and the liquid film formed by the mixture is dense and has good viscoelasticity due to the difference in steric hindrance of the hydrophilic groups, and the macroscopic performance is long stable time, which can improve the pressure-bearing capacity of the temporary plugging agent and reduce the damage to the reservoir.

[0026] Preferably, the film-forming agent is acrylamide-acrylic acid salt copolymer. The acrylamide-acrylic acid salt copolymer can be commercially available or self-prepared. In order to reduce the cost and ensure the stability of the raw material supply, preferably, the acrylamide-acrylic acid salt copolymer is prepared by a method comprising the following steps: polymerizing acrylamide, acrylic acid and maleic anhydride in water under the action of an initiator; after the polymerization reaction is completed, the product obtained by the polymerization reaction is subjected to oxidation treatment with an oxidizing agent; finally, the product after the oxidation treatment is washed with lye, and then the washed product is dried to obtain the acrylamide-acrylic acid salt copolymer.

[0027] Preferably, the initiator is a water-soluble persulfate salt. For example, the initiator is ammonium persulfate, sodium persulfate or potassium persulfate. Preferably, the temperature of the polymerization reaction is 80-88℃. Preferably, the time of the polymerization reaction is not less than 5h. Preferably, the oxidizing agent is concentrated sulfuric acid or concentrated nitric acid. Preferably, the temperature of the oxidation treatment is room temperature. For example, the temperature of the oxidation treatment is 20-23℃. Preferably, the time of the oxidation treatment is 1.4-1.6h. If the temperature of the oxidation treatment is too high, the reaction speed will be too fast, resulting in incomplete reaction.

[0028] Preferably, the mass ratio of the acrylamide, the acrylic acid, the maleic anhydride, the oxidizing agent and the initiator is (2-3):(1-1.5):(1-2):(4-6):(0.5-1.5). Preferably, the mass ratio of the acrylamide, the acrylic acid, the maleic anhydride, the oxidizing agent, the initiator and water is (2-3):(1-1.5):(1-2):(4-6):(0.5-1.5):(2-2.5). For example, the mass ratio of the acrylamide, the acrylic acid, the maleic anhydride, the oxidizing agent, the initiator and water is 2:1:1.5:5:1:2.5. Preferably, the lye is an alkali metal hydroxide solution. For example, the lye is a sodium hydroxide solution. Preferably, the mass fraction of the alkali metal hydroxide solution is 3-5%. Preferably, the mass ratio of the lye and the product after the oxidation treatment is (180-250):5.

[0029] It can be understood that, during the polymerization reaction, the molecular weight of the polymer obtained by the polymerization reaction gradually increases, the water solubility of the polymer becomes poor, and then the polymer is precipitated. Preferably, the method for preparing the acrylamide-acrylic acid salt copolymer further comprises the following step: after the polymerization reaction is completed, the system after the polymerization reaction is subjected to solid-liquid separation, and the solid obtained by the solid-liquid separation is the product obtained by the polymerization reaction.

[0030] Preferably, the method for preparing the acrylamide-acrylic acid salt copolymer further comprises the following step: after the oxidation treatment, the system after the oxidation treatment is mixed with an organic solvent, and then subjected to solid-liquid separation, and the solid obtained by the solid-liquid separation is the product after the oxidation treatment. Preferably, the organic solvent is an alcohol solvent. For example, the organic solvent is methanol or ethanol. Mixing the system after the oxidation treatment with the organic solvent can make the product precipitate, and through the solid-liquid separation, the product after the oxidation treatment can be obtained. Preferably, the mass ratio of the acrylamide to the organic solvent is (2-3):(7-8). For example, the mass ratio of the acrylamide to the organic solvent is 2:7.

[0031] The role of the oxidation treatment of the product obtained by the polymerization reaction with the oxidizing agent is to make the maleic anhydride groups in the copolymer react to generate sulfonated maleic anhydride groups, thereby improving the temperature resistance of the copolymer. The role of the washing of the product after the oxidation treatment with the lye is to neutralize the acidic groups in the product after the oxidation treatment to form corresponding salts, for example, to neutralize the carboxylic acid in the product after the oxidation treatment into a carboxylic acid salt.

[0032] Preferably, the high-temperature stabilizer is triethanolamine and / or a water-soluble sulfite. Preferably, the water-soluble sulfite is an alkali metal sulfite. For example, the water-soluble sulfite is sodium sulfite or potassium sulfite. The role of the high-temperature stabilizer is to improve the temperature resistance of the fuzzy capsule temporary plugging agent system.

[0033] Preferably, the fuzzy capsule temporary plugging agent is prepared by a method comprising the following steps: mixing a formula amount of water and an alkaline compound to obtain a lye, and then sequentially adding a formula amount of a nucleating agent, a fluff agent, a film-forming agent, a capsule layer agent, and a high-temperature stabilizer to the lye, uniformly mixing after each addition of a material to the lye, and uniformly mixing after the addition of the high-temperature stabilizer to obtain the fuzzy capsule temporary plugging agent.

[0034] A method for preparing a fuzzy capsule temporary plugging agent as described above, comprising the following steps: mixing a formula amount of water and an alkaline compound to obtain a lye, and then sequentially adding a formula amount of a nucleating agent, a fluff agent, a film-forming agent, a capsule layer agent, and a high-temperature stabilizer to the lye, uniformly mixing after each addition of a material to the lye, and uniformly mixing after the addition of the high-temperature stabilizer to obtain the fuzzy capsule temporary plugging agent.

[0035] The preparation method of the invention is simple in operation, and the prepared velvet capsule temporary plugging agent has good high-temperature stability and excellent plugging performance, and can meet the plugging requirements of low-pressure gas layers of carbonate rocks.

[0036] Preferably, the mixing is performed by stirring at a speed of not less than 10000r / min for not less than 30min.

[0037] If the nucleating agent, the velvet agent, the film forming agent, the capsule layer agent and the high-temperature stabilizer are added into the alkali solution simultaneously or in a changed order, the system cannot form the velvet capsule structure or the formed velvet capsule structure is unstable, and the plugging capacity is reduced.

[0038] The application of the temporary plugging agent in the development of carbonate rock oil and gas fields.

[0039] The velvet capsule temporary plugging agent of the invention is used in the development of oil and gas fields, and has a pressure-bearing capacity of not less than 19.8MPa at 150℃, excellent plugging performance, and can meet the plugging requirements of low-pressure gas layers of carbonate rocks, and the gel breaking rate can be not less than 98.85%, and the permeability recovery rate of a seamless core can be not less than 87.56%, and the reservoir has excellent protection performance. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 Fig. 1 is a structural schematic diagram of the velvet capsule temporary plugging agent of the invention, wherein the reference signs are as follows: 1-gas core; 2-gas-liquid surface tension reduction film; 3-high-viscosity water layer; 4-high-viscosity water layer fixing film; 5-water-solubility improvement film; 6-polymer high molecule and surfactant concentration transition layer.

[0041] Figure 2 Fig. 2 is an appearance schematic diagram of the velvet capsule temporary plugging agent of Example 1 of the invention observed under a microscope at a magnification of 1200 times. DETAILED DESCRIPTION

[0042] The technical solutions of the invention are further described below in combination with specific examples.

[0043] Example 1

[0044] The velvet capsule temporary plugging agent of the example is composed of the following components in mass fraction: water 100 parts, capsule layer agent 2 parts, velvet agent 1 part, nucleating agent 0.4 part, film forming agent 0.6 part, high-temperature stabilizer 0.8 part, and sodium hydroxide 2 parts; the capsule layer agent is sodium carboxymethyl cellulose, the velvet agent is heat-resistant starch, the nucleating agent is composed of sodium dodecyl sulfonate and sodium dodecyl benzene sulfonate at a mass ratio of 1:1, the film forming agent is acrylamide-acrylic acid salt copolymer, and the high-temperature stabilizer is triethanolamine.

[0045] The heat-resistant starch used in the embodiment is prepared by a method comprising the following steps: adding deionized water into a reaction kettle, then dispersing corn starch into the deionized water to obtain a dispersion, adjusting the pH value of the dispersion to 7 with a 4% sodium hydroxide solution to obtain a pre-reaction solution, then heating the pre-reaction solution to 40°C, adding sodium trimetaphosphate into the reaction kettle, and allowing the mixture in the reaction kettle to react at 40°C and under stirring for 4h, then adding acetic anhydride into the reaction kettle, and allowing the mixture in the reaction kettle to continue to react at 40°C and under stirring for 4h, after the reaction is completed, dehydrating and drying the material in the reaction kettle, and then crushing to obtain the heat-resistant starch with a particle size of no less than 40 mesh; the mass ratio of corn starch, deionized water, sodium trimetaphosphate, and acetic anhydride is 90:195:1.5:4.

[0046] The acrylamide-acrylic acid salt copolymer used in the embodiment is prepared by a method comprising the following steps: adding deionized water, maleic anhydride, and ammonium persulfate into a reaction kettle, allowing the solid material in the reaction kettle to dissolve under heating and stirring, then heating the material in the reaction kettle to 80°C, and then adding acrylamide and acrylic acid, and allowing the mixture to polymerize under stirring for 5h, then filtering, and the yellow solid obtained by filtering is the product of the polymerization reaction, then allowing the product of the polymerization reaction and concentrated sulfuric acid to be subjected to oxidation treatment at 20°C and under stirring for 1.4h, after the oxidation treatment is completed, adding anhydrous ethanol into the system after the oxidation treatment, and the product after the oxidation treatment is precipitated, and after filtering, the product after the oxidation treatment is obtained, and finally, the product after the oxidation treatment is washed using an excess amount of sodium hydroxide solution (the mass fraction of the sodium hydroxide solution is 4%, and the mass ratio of the sodium hydroxide solution and the product after the oxidation treatment is 200:5), and then the solid product after the washing is dried to obtain the acrylamide-acrylic acid salt copolymer; the mass ratio of acrylamide, acrylic acid, maleic anhydride, concentrated sulfuric acid, ammonium persulfate, anhydrous ethanol, and deionized water is 2:1:1.5:5:1:7:2.5.

[0047] The appearance of the temporary plugging agent for the velvet capsule of Example 1 observed under a microscope at a magnification of 1200 times is shown in Figure 2 .

[0048] Example 2

[0049] The temporary plugging agent for the velvet capsule of the embodiment is composed of the following components in mass fractions: water 100 parts, capsule layer agent 1.5 parts, velvet agent 1.2 parts, nucleating agent 0.8 part, film forming agent 0.8 part, high-temperature stabilizer 1.2 part, and sodium hydroxide 1.5 part; the capsule layer agent is sodium carboxymethyl cellulose, the velvet agent is heat-resistant starch, the nucleating agent is composed of sodium dodecyl sulfonate and sodium dodecyl benzene sulfonate at a mass ratio of 1:1.1, the film forming agent is acrylamide-acrylic acid salt copolymer, and the high-temperature stabilizer is triethanolamine.

[0050] The heat-resistant starch used in the embodiment is prepared by a method comprising the following steps: adding deionized water into a reaction kettle, then dispersing corn starch into the deionized water to obtain a dispersion, adjusting the pH value of the dispersion to 7 with a 4% sodium hydroxide solution to obtain a pre-reaction solution, then heating the pre-reaction solution to 40°C, adding sodium trimetaphosphate into the reaction kettle, and allowing the mixture in the reaction kettle to react at 40°C and under stirring for 4h, then adding acetic anhydride into the reaction kettle, and allowing the mixture in the reaction kettle to continue to react at 40°C and under stirring for 4h, after the reaction is completed, dehydrating and drying the material in the reaction kettle, and crushing to obtain the heat-resistant starch with a particle size of not less than 40 mesh; the mass ratio of corn starch, deionized water, sodium trimetaphosphate, and acetic anhydride is 100:210:2.0:5.

[0051] The acrylamide-acrylic acid salt copolymer used in the embodiment is prepared by a method comprising the following steps: adding deionized water, maleic anhydride, and ammonium persulfate into a reaction kettle, allowing the solid material in the reaction kettle to dissolve under heating and stirring, heating the material in the reaction kettle to 88°C, then adding acrylamide and acrylic acid, and allowing the mixture to polymerize under stirring for 5h, then filtering, and the yellow solid obtained by filtering is the product of the polymerization reaction, then allowing the product of the polymerization reaction and concentrated sulfuric acid to be subjected to oxidation treatment at 23°C and under stirring for 1.6h, after the oxidation treatment is completed, adding anhydrous ethanol into the system after the oxidation treatment, and the product after the oxidation treatment is precipitated, and the product after the oxidation treatment is obtained by filtering, and finally using an excess of sodium hydroxide solution (the mass fraction of the sodium hydroxide solution is 5%, and the mass ratio of the sodium hydroxide solution and the product after the oxidation treatment is 180:5) to wash the product after the oxidation treatment, then drying the solid product after the washing to obtain the acrylamide-acrylic acid salt copolymer; the mass ratio of acrylamide, acrylic acid, maleic anhydride, concentrated sulfuric acid, ammonium persulfate, anhydrous ethanol, and deionized water is 3:1.5:1:4:0.5:8:2.

[0052] Example 3

[0053] The fuzzy capsule temporary plugging agent of the embodiment is composed of the following components in mass fraction: water 100 parts, capsule layer agent 2.2 parts, fluff agent 0.8 part, nucleating agent 0.2 part, film forming agent 0.4 part, high temperature stabilizer 1 part, and sodium hydroxide 2.5 parts; the capsule layer agent is sodium carboxymethyl cellulose, the fluff agent is heat-resistant starch, the nucleating agent is composed of sodium dodecyl sulfonate and sodium dodecyl benzene sulfonate in a mass ratio of 1:0.8, the film forming agent is acrylamide-acrylic acid salt copolymer, and the high temperature stabilizer is sodium sulfite.

[0054] The heat-resistant starch used in the example is prepared by a method comprising the following steps: adding deionized water into a reaction kettle, then dispersing corn starch into the deionized water to obtain a dispersion, adjusting the pH value of the dispersion to 7 with a 4% sodium hydroxide solution to obtain a pre-reaction solution, then heating the pre-reaction solution to 40℃, adding sodium trimetaphosphate into the reaction kettle, and allowing the mixture in the reaction kettle to react at 40℃ and under stirring for 4h, then adding acetic anhydride into the reaction kettle, and continuing to allow the mixture in the reaction kettle to react at 40℃ and under stirring for 4h, after the reaction is completed, dehydrating and drying the material in the reaction kettle, and then crushing to obtain heat-resistant starch with a particle size of no less than 40 mesh; the mass ratio of corn starch, deionized water, sodium trimetaphosphate, and acetic anhydride is 95:200:1.8:4.5.

[0055] The acrylamide-acrylic acid salt copolymer used in the example is prepared by a method comprising the following steps: adding deionized water, maleic anhydride, and ammonium persulfate into a reaction kettle, allowing the solid material in the reaction kettle to dissolve under heating and stirring, then heating the material in the reaction kettle to 85℃, then adding acrylamide and acrylic acid, and allowing the mixture to polymerize under stirring for 5h, then filtering, and the yellow solid obtained by filtering is the product of the polymerization reaction, then allowing the product of the polymerization reaction and concentrated sulfuric acid to undergo oxidation treatment at 21℃ and under stirring for 1.5h, after the oxidation treatment is completed, adding anhydrous ethanol into the system after the oxidation treatment, and the product after the oxidation treatment is precipitated, and after filtering, the product after the oxidation treatment is obtained, and finally using an excess of sodium hydroxide solution (the mass fraction of the sodium hydroxide solution is 3%, and the mass ratio of the sodium hydroxide solution and the product after the oxidation treatment is 250:5) to wash the product after the oxidation treatment, then drying the solid product after the washing to obtain the acrylamide-acrylic acid salt copolymer; the mass ratio of acrylamide, acrylic acid, maleic anhydride, concentrated sulfuric acid, ammonium persulfate, anhydrous ethanol, and deionized water is 2.5:1.2:2:6:1.5:7.5:2.2.

[0056] Example 4

[0057] The fuzzy capsule temporary plugging agent of the example is composed of the following components in mass fraction: water 100 parts, capsule layer agent 2.5 parts, fluff agent 1.5 parts, nucleating agent 0.66 parts, film forming agent 1 part, high temperature stabilizer 1.5 parts, and sodium hydroxide 2 parts; the capsule layer agent is sodium carboxymethyl cellulose, the fluff agent is heat-resistant starch, the nucleating agent is composed of sodium dodecyl sulfonate and sodium dodecyl benzene sulfonate at a mass ratio of 1:1.2, the film forming agent is acrylamide-acrylic acid salt copolymer, and the high temperature stabilizer is sodium sulfite.

[0058] The heat-resistant starch used in the example is the same as the heat-resistant starch used in Example 1, and the acrylamide-acrylic acid salt copolymer used in the example is the same as the acrylamide-acrylic acid salt copolymer used in Example 1.

[0059] Example 5

[0060] The difference between the fuzzy capsule temporary plugging agent of the present example and the fuzzy capsule temporary plugging agent of Example 1 is that the nucleating agent used in the fuzzy capsule temporary plugging agent of the present example is sodium carboxymethyl starch.

[0061] Example 6

[0062] The difference between the fuzzy capsule temporary plugging agent of the present example and the fuzzy capsule temporary plugging agent of Example 1 is that the nucleating agent used in the fuzzy capsule temporary plugging agent of the present example is lauryl isopropyl alcohol amine.

[0063] The preparation method of the fuzzy capsule temporary plugging agent of Examples 1-6 specifically comprises the following steps: adding sodium hydroxide into a formula amount of deionized water to obtain an alkali solution, and then adding a formula amount of a nucleating agent, a fluff agent, a film-forming agent, a capsule layer agent, and a high-temperature stabilizer into the alkali solution in sequence, and stirring at a speed of 10,000 r / min for 30 min after adding each material into the alkali solution.

[0064] Comparative Example 1

[0065] The difference between the fuzzy capsule temporary plugging agent of the present example and the fuzzy capsule temporary plugging agent of Example 1 is that the nucleating agent used in the fuzzy capsule temporary plugging agent of the present example is sodium dodecyl sulfonate.

[0066] Comparative Example 2

[0067] The difference between the fuzzy capsule temporary plugging agent of the present example and the fuzzy capsule temporary plugging agent of Example 1 is that the nucleating agent used in the fuzzy capsule temporary plugging agent of the present example is sodium dodecyl benzene sulfonate.

[0068] Comparative Example 3

[0069] The difference between the fuzzy capsule temporary plugging agent of the present example and the fuzzy capsule temporary plugging agent of Example 1 is that the nucleating agent used in the fuzzy capsule temporary plugging agent of the present example is composed of sodium dodecyl sulfonate, polyoxyethylene octyl phenol ether, dodecyl dimethyl ammonium oxide, and triethanolamine dodecyl sulfate salt with a mass ratio of 1:1:1:1.

[0070] Comparative Example 4

[0071] The difference between the fuzzy capsule temporary plugging agent of the present example and the fuzzy capsule temporary plugging agent of Example 1 is that the fluff agent used in the fuzzy capsule temporary plugging agent of the present example is composed of xanthan gum and polyvinyl pyrrolidone with a mass ratio of 2:3.

[0072] Comparative Example 5

[0073] The difference between the fuzzy capsule temporary plugging agent of the present example and the fuzzy capsule temporary plugging agent of Example 1 is that the capsule layer agent used in the fuzzy capsule temporary plugging agent of the present example is composed of carboxymethyl starch and polyanionic cellulose with a mass ratio of 4:1.

[0074] Comparative Example 6

[0075] The difference between the fuzz capsule temporary plugging agent of the present comparative example and the fuzz capsule temporary plugging agent of Example 1 is that the high temperature stabilizer used in the temporary plugging agent of the present comparative example is lead stearate.

[0076] The preparation method of the temporary plugging agent of Comparative Example 1-6 specifically comprises the following steps: adding sodium hydroxide into a formula amount of deionized water to obtain a lye, and then adding a formula amount of nucleating agent, fuzz agent, film forming agent, capsule layer agent and high temperature stabilizer into the lye in sequence, and stirring at a speed of 10000 r / min for 30 min after adding each material into the lye.

[0077] Comparative Example 7

[0078] The difference between the temporary plugging agent of the present comparative example and the temporary plugging agent of Example 1 is that the mass fraction of sodium hydroxide used in the temporary plugging agent of the present comparative example is 1.

[0079] The preparation method of the temporary plugging agent of Comparative Example 7 specifically comprises the following steps: adding a formula amount of nucleating agent, fuzz agent, film forming agent, capsule layer agent and high temperature stabilizer into deionized water in sequence, and stirring at a speed of 10000 r / min for 30 min after adding each material.

[0080] Comparative Example 8

[0081] The temporary plugging agent of the present comparative example is prepared by the method comprising the following steps: adding sodium hydroxide (the mass ratio of sodium hydroxide to water is the same as that in Example 1) into 100 parts of deionized water to obtain a lye, and then adding 0.5 parts of polypropylene fiber, 2.5 parts of guar gum, 0.5 parts of 2-propen-1-ol and 1 part of triethanolamine into the lye in sequence, and stirring at a speed of 10000 r / min for 30 min after adding each material into the lye.

[0082] Experimental Example 1

[0083] In order to evaluate the high temperature stability of the temporary plugging agents of Examples 1-6 and Comparative Examples 1-8, the density and rheological properties of the temporary plugging agents were tested according to the method specified in the standard SY / T5107-2005 “Method for evaluating the performance of water-based fracturing fluid”, and the changes in the density and rheological properties of the temporary plugging agents after hot rolling at 150℃ for 6h were tested, and the test results are shown in Table 1. PV in Table 1 represents plastic viscosity, YP represents dynamic shear force, and YP / PV represents dynamic plastic ratio.

[0084] Table 1 High temperature stability of the temporary plugging agents of Examples 1-6 and Comparative Examples 1-8

[0085]

[0086]

[0087] As shown in Table 1, the densities of the temporary plugging agents of Examples 1-6 and Comparative Examples 1-8 all increase after hot rolling at 150°C, because the internal structure of the temporary plugging agent system is partially degraded. After hot rolling at 150°C, the rheological property change of the temporary plugging agent of Examples 1-6 is smaller compared with that of the temporary plugging agent of Comparative Example 8, indicating that the high-temperature stability of the temporary plugging agent of Examples 1-6 is better.

[0088] Experimental Example 2

[0089] In order to evaluate the structural stability of the temporary plugging agents of Examples 1-6 and Comparative Examples 1-8, the pressure-bearing capacity of the temporary plugging agents after hot rolling at 150°C for 6h was tested by using a permeability meter, and a core with a width of 25mm, a length of 38mm and a fracture width of 2.0mm was selected as the experimental core. The results are shown in Table 2.

[0090] Table 2 Pressure-bearing capacity of the temporary plugging agents of Examples 1-6 and Comparative Examples 1-8

[0091]

[0092]

[0093] As shown in Table 2, the pressure-bearing capacity of the temporary plugging agents of Examples 1-6 can reach more than 19.8MPa after hot rolling at 150°C for 6h, while the pressure-bearing capacity of the temporary plugging agent of Comparative Example 8 is 13.6MPa, indicating that the structural stability of the temporary plugging agents of Examples 1-6 is better.

[0094] Experimental Example 3

[0095] In order to evaluate the plugging capacity of the temporary plugging agents of Examples 1-6, Comparative Examples 1-2 and 8, a core plug was drilled from a rock sample in the direction of oil and gas flow to obtain an experimental core, and the core had a diameter of 25mm and a length of 38mm. A fracture with a height of 20mm and a width of 0.01mm, 0.2mm, 1mm, 2mm or 4mm was made on the experimental core by using an artificial fracture tool. The fracture with a width of 0.01mm and 0.2mm was used to simulate natural fractures of a reservoir, and the fracture with a width of 1mm, 2mm or 4mm was used to simulate acid-etched fractures. The pressure-bearing capacity of the temporary plugging agents after plugging the cores containing natural fractures and acid-etched fractures at 150°C was determined to evaluate the plugging capacity of the temporary plugging agents for plugging natural fractures and acid-etched fractures of carbonate rocks. The pressure-bearing capacity of the temporary plugging agents of Examples 1-6, Comparative Examples 1-2 and 8 after plugging fractures with different widths at 150°C is shown in Table 3.

[0096] Table 3 pressure-bearing capacity of the temporary plugging agents of examples 1-6, comparative examples 1-2 and 8 after plugging fractures with different fracture widths at 150℃

[0097]

[0098]

[0099] As shown in Table 3, the pressure-bearing capacity of the temporary plugging agents in the core gradually decreases with the increase of the fracture width. The plugging capacity of the temporary plugging agent to natural fractures is the highest. The plugging pressure-bearing capacity of the fuzzy capsule temporary plugging agent of examples 1-6 to acid-etched fractures changes obviously with the fracture width, and the lowest is 21.58 MPa. The plugging pressure-bearing capacity of the temporary plugging agent of comparative example 8 to acid-etched fractures is the lowest, which is 11.37 MPa. Therefore, the fuzzy capsule temporary plugging agent provided by the application can meet the acid fracturing temporary plugging requirement.

[0100] Experimental example 4

[0101] In order to evaluate the gel breaking capacity of the temporary plugging agents of examples 1-6 and comparative examples 1-8, the gel breaking process of the temporary plugging agents of examples 1-6 and comparative examples 1-8 was reproduced in the laboratory by using a rheometer according to the method specified in the standard SY / T5107-2005 “Method for evaluating the performance of water-based fracturing fluid”, and the rheological properties in the gel breaking process and the residue mass after gel breaking were recorded in real time. Then, the gel breaking rate was calculated according to the total mass of the solutes in the temporary plugging agent used in the experiment, and the gel breaking rate = 1-(residue mass / total mass of solutes in the temporary plugging agent x 100%). The temporary plugging agents of examples 1-6 and comparative examples 1-8 can all self-degrade under the formation temperature after a sufficient time, in which the temporary plugging agent of comparative example 8 is hydrolyzed into water-soluble acid monomers, and the fuzzy capsule temporary plugging agents of examples 1-6 are degraded into small molecule polymers. In order to quickly gel break, ammonium persulfate is selected as a gel breaker to accelerate the gel breaking process of the temporary plugging agent. In the experimental process, the volume of each temporary plugging agent is 100 mL, and the mass ratio of the total mass of the solutes in each temporary plugging agent to the mass of the gel breaker is the same. The gel breaking experimental results of the temporary plugging agents of examples 1-6 and comparative examples 1-8 are shown in Table 4.

[0102] Table 4 gel breaking experimental results of the temporary plugging agents of examples 1-6 and comparative examples 1-8

[0103] Temporary plugging agent Break rate / % Example 1 98.85 Example 2 99.13 Example 3 99.06 Example 4 98.98 Example 5 99.33 Example 6 98.45 Comparative Example 1 96.89 Comparative Example 2 97.15 Comparative Example 3 95.66 Comparative Example 4 96.23 Comparative Example 5 92.12 Comparative Example 6 98.97 Comparative Example 7 98.01 Comparative Example 8 90.18

[0104] As shown in Table 4, the gel breaking rate of the temporary plugging agents of examples 1-6 is the lowest, which is 98.85%, and the gel breaking rate of comparative example 8 is 90.18%. Therefore, the gel breaking rate of the temporary plugging agents of examples 1-6 is higher, and the gel breaking performance is better.

[0105] Experimental example 5

[0106] In order to evaluate the reservoir damage of the temporary plugging agents of Examples 1-6 and Comparative Examples 1-8, carbonate natural cores were selected to make core plungers with a diameter of 25 mm and a length of 38 mm to 45 mm, and artificial fractures were made to form long fractures with a fracture width of 1 mm and a fracture length of 20 mm, and short fractures with a fracture width of 1 mm and a fracture length of 10 mm. The core containing the long fractures was named long fracture core, the core containing the short fractures was named short fracture core, and the core without fractures was named fractureless core. Then, the permeameter was used to simulate the formation seepage in the laboratory to evaluate the reservoir damage of the temporary plugging agents. In this experiment, the reservoir damage of the temporary plugging agents was evaluated by testing the permeability recovery rate. The testing method of the permeability recovery rate was as follows: (1) initial permeability determination of the core, the standard brine was displaced from the reverse end of the core to the core plunger, and when the liquid flowed out of the outlet end, the liquid outflow was recorded until the flow rate was stable, and the stable permeability value K1 was calculated; (2) the temporary plugging agent was added to the water to form a dispersion, and then a gel breaker was added, and after the temporary plugging agent was completely broken, a temporary plugging agent gel breaking liquid was obtained. The mass fraction of the temporary plugging agent in the dispersion prepared by different temporary plugging agents was the same, and the same gel breaker was added to the dispersion prepared by different temporary plugging agents, and the mass ratio of the gel breaker to the temporary plugging agent in the dispersion was equal. Then, the temporary plugging agent gel breaking liquid was pumped into the core at a constant flow rate, and when the liquid flowed out of the outlet end, the outflow was recorded until the flow rate was stable, and the temporary plugging agent gel breaking liquid was allowed to contact and infiltrate the core for 2 h. (3) Then, the standard brine was displaced from the reverse end of the core to the core plunger, and when the liquid flowed out of the outlet end, the liquid outflow was recorded until the flow rate was stable, and the stable permeability value K2 was recorded. The ratio of K2 to K1 was the permeability recovery rate. The test results of the reservoir damage of the temporary plugging agents of Examples 1-6 and Comparative Examples 1-8 are shown in Table 5.

[0107] Table 5 Reservoir damage of the temporary plugging agents of Examples 1-6 and Comparative Examples 1-8

[0108]

[0109] As shown in Table 5, the longer the fracture length, the higher the permeability recovery value, indicating that the fracture seepage channel is more easily to discharge the reservoir pollutants such as the temporary plugging agent relative to the core matrix (fractureless core). The permeability recovery rate of the temporary plugging agents of Examples 1-6 to the fractureless core can reach more than 87.56%, while the permeability recovery rate of the temporary plugging agent of Comparative Example 8 to the fractureless core is only 37.17%, indicating that the temporary plugging agents of Examples 1-6 have excellent reservoir protection performance and less damage.

[0110] In other embodiments, cassava starch or wheat starch is used, phosphorus oxychloride, sodium pyrophosphate or sodium tripolyphosphate is used as the cross-linking agent, propionic anhydride or butyric anhydride is used as the esterifying agent, and the heat-resistant starch is prepared according to the preparation method of the heat-resistant starch in Embodiments 1-3. The heat-resistant starch is used as the fluffing agent in the fluff plug temporary plugging agent, and the performance of the obtained fluff plug temporary plugging agent is close to that of the fluff plug temporary plugging agent in Embodiments 1-3.

Claims

1. A fuzz capsule temporary plugging agent, characterized in that, The basic compound and the following components in mass parts: water 100 parts, capsule layer agent 1.5-2.5 parts, fluff agent 0.8-1.5 parts, nucleating agent 0.2-0.8 parts, film forming agent 0.4-1 part, high temperature stabilizer 0.8-1.5 parts; the fluff agent is heat-resistant starch: the pH of a dispersion liquid mainly composed of starch and water is adjusted to neutral to obtain a pre-reaction liquid, then the pre-reaction liquid and a cross-linking agent are subjected to a first mixing reaction at not less than 40 DEG C for not less than 4 hours, then the system after the first mixing reaction and an esterification agent are subjected to a second mixing reaction at not less than 40 DEG C for not less than 4 hours, and finally the system after the second mixing reaction is dried and crushed to obtain the heat-resistant starch; the cross-linking agent is trimetaphosphate, phosphorus oxychloride, pyrophosphate or tripolyphosphate; the esterification agent is an acid anhydride compound; and the high temperature stabilizer is triethanolamine and / or water-soluble sulfite.

2. The fuzz capsule bridging agent of claim 1, wherein, The basic compound is alkali metal hydroxide; and the mass part of the basic compound is 1.5-2.5 parts.

3. The fuzz capsule bridging agent of claim 1, wherein, The capsule layer agent is carboxymethyl cellulose salt and / or carboxymethyl starch salt; the carboxymethyl cellulose salt is alkali metal carboxymethyl cellulose salt; and the carboxymethyl starch salt is alkali metal carboxymethyl starch salt.

4. The fuzz capsule bridging agent of claim 1, wherein, The particle size of the heat-resistant starch is not less than 40 mesh.

5. The fuzz capsule bridging agent of claim 4, wherein, The mass ratio of the starch, cross-linking agent and esterification agent is (90-100):(1.5-2.0):(4-5).

6. The fuzz capsule bridging agent of claim 4, wherein, The trimetaphosphate is sodium trimetaphosphate or potassium trimetaphosphate; the pyrophosphate is sodium pyrophosphate or potassium pyrophosphate; the tripolyphosphate is sodium tripolyphosphate or potassium tripolyphosphate; and the esterification agent is acetic anhydride, propionic anhydride or butyric anhydride.

7. The fuzzy capsule bridge plug according to any one of claims 1 to 6, wherein, The nucleating agent is surfactant; the nucleating agent is anionic surfactant and / or non-ionic surfactant; the anionic surfactant is alkyl sulfonate and / or alkyl benzene sulfonate; the non-ionic surfactant is alkyl acyl alcohol amine; the anionic surfactant includes dodecyl sulfonate and dodecyl benzene sulfonate; and the mass ratio of the dodecyl sulfonate and dodecyl benzene sulfonate is 1:(0.8-1.2).

8. The fuzzy capsule bridge plug of any one of claims 1-6, wherein, The water-soluble sulfite is sodium sulfite or potassium sulfite.

9. The fuzzy capsule bridging agent of any one of claims 1-6, wherein, The film-forming agent is an acrylamide-acrylic acid salt copolymer; the acrylamide-acrylic acid salt copolymer is prepared by a method comprising the following steps: polymerizing acrylamide, acrylic acid and maleic anhydride in water under the action of an initiator; after the polymerization reaction is completed, the product obtained by the polymerization reaction is subjected to oxidation treatment with an oxidizing agent, the product after the oxidation treatment is washed with lye, and then the washed product is dried to obtain the acrylamide-acrylic acid salt copolymer; the initiator is a water-soluble persulfate; the temperature of the polymerization reaction is 80-88 DEG C; the time of the polymerization reaction is not less than 5 h; the mass ratio of the acrylamide, the acrylic acid, the maleic anhydride, the oxidizing agent and the initiator is (2-3):(1-1.5):(1-2):(4-6):(0.5-1.5); the oxidizing agent is concentrated sulfuric acid and concentrated nitric acid; the time of the oxidation treatment is 1.4-1.6 h.

10. A method of preparing the fuzz bale bridging agent according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: mixing formula amount of water and alkaline compound to obtain lye, then sequentially adding formula amount of nucleating agent, fluffing agent, film-forming agent, capsule layer agent and high-temperature stabilizer into the lye, mixing uniformly after adding each material, and obtaining the temporary plugging agent for fluff and capsule after mixing uniformly after adding the high-temperature stabilizer.

Images