A kind of clear water or low viscosity slick water portable ultra-low density high-strength resin proppant and its preparation method

Abstract

The application discloses a kind of clear water or low viscosity slick water portable ultra-low density high-strength resin proppant.The proppant is prepared by dispersing polymerization and curing after mixture comprising 15-50wt% vinyl monomer, 5-10wt% acrylate monomer and 50-70wt% unsaturated resin.The preparation method comprises: the resin composition is formed in aqueous phase by dispersing agent and speed control, and the spherical droplet with particle size of 12-140 mesh and nearly 100% sphericity is formed; then at 30-80 DEG C.The proppant of the application has ultra-low density, and can be carried by clear water or low viscosity slick water, suitable for low viscosity fracturing fluid, low discharge construction and small-scale fracturing, can realize ultra-remote seam network support, and greatly improve the oil and gas drainage area.The breakage rate is less than 2% under 20-90MPa closure pressure, and the surface is weakly lipophilic, and the oil phase conductivity is higher than the water phase conductivity.

Description

Technical Field

[0001] This invention relates to the technical field of resin proppant, and more particularly to an ultra-low density, high strength resin proppant that can be carried by water or low-viscosity slippery water and its preparation method. Background Technology

[0002] Oil and gas extraction typically requires hydraulic fracturing technology, and proppant is a key material in fracturing operations. Also known as oil fracturing proppant, proppant is used in deep oil and gas well production. After fracturing in high-pressure, low-permeability deposits, the oil and gas-bearing rock formations are fractured, allowing oil and gas to flow through the channels created by the fractures. At this point, fluid is injected into the rock matrix at pressures exceeding the formation's fracturing strength, causing fractures to form around the wellbore and creating a highly conductive channel. To maintain the fractures created after fracturing and ensure the smooth flow of oil and gas products, a mixture of proppant and fracturing fluid is pumped into the wellbore at high pressure and speed using hydraulic fracturing. This mixture fills the rock fractures, utilizing the proppant's pressure resistance to create a good flow channel, preventing the fractures from closing due to stress release. This maintains high conductivity, ensuring smooth oil and gas flow and increasing production.

[0003] In the prior art, the preparation method of self-suspended proppant for water fracturing, disclosed in CN120795896A, changes the solid ceramsite to a porous reinforced structure, introduces self-healing function, uses bio-based polymers to replace traditional surfactants to improve environmental friendliness, and introduces nano-deposition and microwave technology.

[0004] Although the aforementioned proppant has compressive strength enhancement and self-healing properties, its high density requires a high-viscosity liquid to carry it, which makes ultra-far-end support difficult and its strong hydrophilicity may inhibit oil phase flow. Summary of the Invention

[0005] The purpose of this invention is to provide an ultra-low density, high strength resin proppant that can be carried by clear water or low-viscosity slippery water and its preparation method, so as to solve the technical problems of existing proppants, such as high density, need for high-viscosity liquid to carry, difficulty in supporting at ultra-far ends, and strong hydrophilicity that may inhibit oil phase flow, and achieve the purpose of ultra-low density, ultra-high strength, controllable particle size, weak oleophilicity and excellent temperature resistance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An ultra-low density, high-strength resin support that can be carried by clear water or low-viscosity slippery water is obtained by curing a resin composition comprising the following components in weight percentages:

[0008] Vinyl monomers 15-50 wt%, acrylate monomers 5-10 wt%, unsaturated resins 50-70 wt%;

[0009] The proppant has a bulk density of 0.6-0.8 g / cm³, an apparent density of 1.08-1.3 g / cm³, a particle size of 12-140 mesh, and a breakage rate of less than 2 wt% under a closure pressure of 90 MPa.

[0010] As a preferred embodiment of the present invention, the vinyl monomer is one or more selected from styrene, divinylbenzene, and vinyltoluene;

[0011] The acrylate monomer is selected from one or more of methyl methacrylate, butyl methacrylate, dicyclopentadiene acrylate, and isobornyl acrylate.

[0012] Another object of the present invention is to provide a method for preparing an ultra-low density, high strength resin support that can be carried by clear water or low-viscosity slippery water.

[0013] Including ultra-low density, high-strength resin proppant that can be carried by clear water or low-viscosity slippery water, as described above.

[0014] It also includes the following steps:

[0015] Step 1: Prepare the oil phase: Mix the vinyl monomer, acrylate monomer, unsaturated resin and curing agent evenly to form a homogeneous resin mixture;

[0016] Step 2: Dispersion granulation: The resin mixture obtained in Step 1 is added to the aqueous phase containing the dispersant under stirring. By controlling the stirring speed and the amount of dispersant added, the resin mixture is dispersed in the aqueous phase to form spherical droplets of 12-140 mesh.

[0017] Step 3: Curing and molding: Add an accelerator to the system obtained in step 2, and carry out a curing reaction at a reaction temperature of 30-80℃ to form cured spherical particles;

[0018] Step 4: Post-processing: After the reaction is complete, the product is filtered, washed and dried to obtain the ultra-low density proppant product.

[0019] As a preferred embodiment of the present invention, the dispersant in step 2 is one or more of gelatin, calcium phosphate, hydroxypropyl methylcellulose, sodium polyacrylate, and gum arabic.

[0020] As a preferred embodiment of the present invention, in step 2, the stirring speed is 200-2000 rpm.

[0021] As a preferred embodiment of the present invention, in step 1, the curing agent is one or more of methyl ethyl ketone peroxide, cyclohexanone peroxide, diisopropylbenzene peroxide, tert-butylperoxide-2-ethylhexanoate, and azobisisobutyronitrile.

[0022] As a preferred embodiment of the present invention, the amount of curing agent added is 0.5-2 wt% of the total mass of the resin composition.

[0023] As a preferred embodiment of the present invention, in step 3, the accelerator is one or more of cobalt naphthenate, cobalt isooctanoate, zinc isooctanoate, dimethylaniline derivatives, and metal salts of acetylacetone.

[0024] As a preferred embodiment of the present invention, the amount of the accelerator added is 0.1-0.5 wt% of the total mass of the resin composition.

[0025] As a preferred embodiment of the present invention, in step 3: the rate and temperature of the curing reaction are controlled by adjusting the amount of accelerator added and the water temperature in the jacket of the reactor.

[0026] The beneficial effects of this invention are:

[0027] 1. This invention successfully solves the problems of existing proppants, such as high density, need for high-viscosity liquid transport, difficulty in supporting at extremely far points, and the potential for strong hydrophilicity to inhibit oil phase flow. The proppant prepared using a pure thermosetting resin formulation and aqueous dispersion method does not rely on any inorganic fillers. It possesses comprehensive advantages including ultra-low density, ultra-high strength, controllable particle size, weak oleophilicity, and excellent temperature resistance. It is particularly suitable for low-displacement, small-scale, extremely far-point fracturing stimulation of unconventional oil and gas reservoirs, and has enormous market application potential. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1:

[0030] An ultra-low density, high-strength resin proppant that can be carried by clear water or low-viscosity slippery water is prepared by curing a resin composition comprising the following components in weight percentage: 15-50 wt% vinyl monomer, 5-10 wt% acrylate monomer, and 50-70 wt% unsaturated resin; the proppant has a bulk density of 0.6-0.8 g / cm³, an apparent density of 1.08-1.3 g / cm³, a particle size of 12-140 mesh, and a breakage rate of less than 2 wt% under a closing pressure of 90 MPa.

[0031] The vinyl monomer is, but is not limited to, one or more of styrene, divinylbenzene, and vinyltoluene;

[0032] The acrylate monomer is selected from one or more of methyl methacrylate, butyl methacrylate, dicyclopentadiene acrylate, and isobornyl acrylate.

[0033] Example 2: A method for preparing an ultra-low density high strength resin proppant that can be carried by water or low-viscosity slippery water, comprising the above-mentioned ultra-low density high strength resin proppant that can be carried by water or low-viscosity slippery water.

[0034] It also includes the following steps:

[0035] Step 1: Preparation of the oil phase: The vinyl monomer, acrylate monomer, unsaturated resin, and curing agent are mixed evenly to form a homogeneous resin mixture. In this embodiment, the curing agent is one or more of, but not limited to, methyl ethyl ketone peroxide, cyclohexanone peroxide, dicumyl peroxide, tert-butyl peroxide-2-ethylhexanoate, and azobisisobutyronitrile. The amount of curing agent added is 0.5-2 wt% of the total mass of the resin composition.

[0036] Step 2: Dispersion and Granulation: The resin mixture obtained in Step 1 is added to the aqueous phase containing the dispersant under stirring. By controlling the stirring speed and the amount of dispersant added, the resin mixture is dispersed in the aqueous phase to form spherical droplets of 12-140 mesh. The dispersant can be one or more of gelatin, calcium phosphate, hydroxypropyl methylcellulose, sodium polyacrylate, and gum arabic. The stirring speed is 200-2000 rpm.

[0037] Step 3: Curing and Molding: An accelerator is added to the system obtained in Step 2, and a curing reaction is carried out at a reaction temperature of 30-80°C to form cured spherical particles. The accelerator is one or more of, but not limited to, cobalt naphthenate, cobalt isooctanoate, zinc isooctanoate, dimethylaniline derivatives, and acetylacetone metal salts. The amount of accelerator added is 0.1-0.5 wt% of the total mass of the resin composition. In this embodiment, the dimethylaniline derivative is, but not limited to, N,N-dihydroxyethyl-p-toluidine.

[0038] In this embodiment, the rate and temperature of the curing reaction are controlled by adjusting the amount of accelerator added and the water temperature in the reactor jacket.

[0039] Step 4: Post-processing: After the reaction is complete, the product is filtered, washed and dried to obtain the ultra-low density proppant product.

[0040] In summary, this study successfully addresses the problems of existing proppants, such as high density, the need for high-viscosity liquid transport, difficulty in supporting proppants at extremely far points, and the potential for strong hydrophilicity to inhibit oil phase flow. The proppant prepared using a pure thermosetting resin formulation and aqueous dispersion method does not rely on any inorganic fillers and possesses comprehensive advantages including ultra-low density, ultra-high strength, controllable particle size, weak oleophilicity, and excellent temperature resistance. It is particularly suitable for low-displacement, small-scale, extremely far-point fracturing stimulation of unconventional oil and gas reservoirs, and has enormous market application potential.

[0041] Example 3: A method for preparing an ultra-low density high strength resin proppant that can be carried by water or low-viscosity slippery water, comprising the above-mentioned ultra-low density high strength resin proppant that can be carried by water or low-viscosity slippery water.

[0042] It also includes the following formulations and preparation methods:

[0043] Resin composition: 60 parts unsaturated resin (phthalic type), 35 parts styrene, 5 parts divinylbenzene, and 8 parts methyl methacrylate.

[0044] Curing agent: Methyl ethyl ketone peroxide, accounting for 1.5% of the total mass of the resin composition.

[0045] Aqueous phase: 500 parts deionized water, 2 parts dispersant hydroxypropyl methylcellulose (HPMC).

[0046] Accelerator: Cobalt naphthenate (cobalt content 0.6%), accounting for 0.3% of the total mass of the resin composition.

[0047] Preparation method:

[0048] Preparation of the oil phase: Add unsaturated resin, styrene, divinylbenzene, methyl methacrylate and methyl ethyl ketone peroxide to the reaction vessel and stir for 2 hours until the mixture is homogeneous.

[0049] Preparation of the aqueous phase: Add hydroxypropyl methylcellulose to deionized water, stir until completely dissolved at room temperature, and then transfer to a polymerization reactor equipped with a stirrer and a warm water jacket.

[0050] Dispersion granulation: Start the polymerization reactor and adjust the stirring speed to 1000 rpm. Slowly add the oil phase mixture dropwise to the aqueous phase. After the addition is complete, continue stirring at this speed for 30 minutes to form uniform spherical droplets with a particle size of about 30-50 mesh (0.3-0.6 mm).

[0051] Curing and molding: Hot water is introduced through a jacket to raise the system temperature to 50°C. Cobalt naphthenate accelerator is slowly added, and the reaction is allowed to proceed for 8 hours to allow the spherical droplets to completely solidify.

[0052] Post-processing: After the reaction was completed, the product was filtered and separated, washed three times with hot water to remove the dispersant, and finally dried in an oven at 60°C for 12 hours to obtain a white spherical support product.

[0053] Product performance testing:

[0054] Bulk density: 0.70 g / cm³ (according to SY / T5108-2014 "Test Method for Performance of Fracturing Proppants");

[0055] Apparent density: 1.10 g / cm³ (according to SY / T5108-2014);

[0056] Sphericity / Roundness: ≥0.98 (according to SY / T5108-2014);

[0057] Relationship between closing pressure and breakage rate (based on SY / T5108-2014 test):

[0058]

[0059] Conductivity test (based on SY / T6302-2019 "Evaluation Method for Short-Term Conductivity of Fracturing Proppant Filling Layer", at a proppant concentration of 4.88 kg / m²):

[0060] Oil flowability test (using No. 2 white oil):

[0061]

[0062] Water conductivity test (using 2% KCl solution):

[0063]

[0064] Results Analysis: The proppant prepared in Example 3 exhibited ultra-low density and extremely high strength. Under an ultra-high closure pressure of 90 MPa, the breakage rate was only 1.78%, far below the industry standard (typically requiring ≤5%), and its anti-breakage performance was significantly superior to conventional ceramsite and quartz sand. Conductivity test data clearly showed that its conductivity in oil-phase media was consistently higher than its conductivity in aqueous-phase media, verifying its "weakly oleophilic" surface characteristics. This characteristic is highly advantageous for the extraction of liquid hydrocarbons such as shale oil, effectively reducing water lock damage and improving crude oil production efficiency.

[0065] Example 4: A method for preparing an ultra-low density high strength resin proppant that can be carried by water or low viscosity slippery water, comprising the above-mentioned ultra-low density high strength resin proppant that can be carried by water or low viscosity slippery water.

[0066] It also includes the following formulations and preparation methods:

[0067] Resin composition: 55 parts unsaturated resin (isophthalic type), 40 parts vinyltoluene, and 5 parts dicyclopentadiene acrylate.

[0068] Curing agent: dicumyl peroxide (DCP), accounting for 1.2% of the total mass of the resin composition.

[0069] Aqueous phase: 500 parts deionized water, 3 parts total of sodium polyacrylate and calcium phosphate dispersant mixed at a 1:1 ratio.

[0070] Accelerator: Cobalt isooctanoate, accounting for 0.4% of the total mass of the resin composition.

[0071] Preparation method:

[0072] The preparation steps were the same as in Example 1. The stirring speed was adjusted to 1800 rpm, and a fine-particle proppant with a particle size of 70-120 mesh (0.125-0.212 mm) was successfully prepared.

[0073] Product performance testing:

[0074] Bulk density: 0.68 g / cm³;

[0075] Apparent density: 1.05 g / cm³;

[0076] Breakage rate under 60MPa closing pressure: 1.05%.

[0077] This embodiment demonstrates that, without using any fillers, proppant with finer particle size while maintaining excellent anti-breakage properties can be effectively prepared simply by adjusting the resin composition formulation and process parameters (such as stirring speed), proving the good processing adaptability and mechanical properties of the pure resin system.

[0078] Example 5: Comparative experiment on the suspension and settling performance of proppant in low-viscosity slick water:

[0079] Objective: To verify the superior suspension performance of the proppant of the present invention in low-viscosity fracturing fluid, with a settling rate much lower than that of conventional quartz sand and ceramsite, thus proving that it is more easily carried to the distant fracture.

[0080] Test method:

[0081] Sample preparation: Take the proppant of the present invention prepared in Example 3 (labeled as sample A), conventional low-density ceramsite (labeled as sample B, with a bulk density of about 1.55 g / cm³) and quartz sand (labeled as sample C, with a bulk density of about 1.65 g / cm³), and take all samples with a particle size of 30-50 mesh.

[0082] Prepare fracturing fluid: Prepare slickwater with a viscosity of approximately 3 mPa·s (low-viscosity fracturing fluid commonly used in simulated field operations), which contains 0.05% drag reducer.

[0083] Sedimentation experiment: Using a 1L graduated cylinder, add 800mL of slickwater to each cylinder. Then, slowly and evenly add 10g of each of the three proppant samples to the graduated cylinder and start timing. Record the time required for the proppant particles to settle to the bottom of the graduated cylinder (500mm mark) under static conditions, and calculate their static settling rate (mm / s).

[0084] Test results:

[0085]

[0086] Results analysis:

[0087] The experimental results show that, in the same low-viscosity slickwater, the ultra-low density proppant of this invention (sample A) has an extremely slow settling rate, failing to settle completely within one hour. Its settling rate is significantly lower than that of conventional ceramsite and quartz sand (less than 1 / 60th of the latter two). This is attributed to its ultra-low bulk density (1.08-1.3 g / cm³), resulting in a much lower net gravitational force on it in fracturing fluid compared to the other two proppant types. This characteristic means that during fracturing operations, the proppant of this invention can be easily carried using clean water or low-viscosity slickwater, enabling longer-distance transport and more uniform sand spreading, effectively supporting the distal fracture network, and thus significantly increasing the oil and gas drainage area.

[0088] Example 6: Comparison of proppant embedding and short-term conductivity in coal, shale, and sandstone slabs

[0089] Objective: To evaluate the embedding behavior of the proppant of the present invention on the surface of different lithologies (especially soft coal and shale) and its effect on fracture conductivity.

[0090] Test method:

[0091] 1. Samples and rock slabs:

[0092] Support: The support of the present invention (30-50 mesh) prepared in Example 3.

[0093] Comparative proppant: 30-50 mesh quartz sand.

[0094] Rock slabs: Prepare or select one pair each of coal rock, shale and sandstone rock slabs with smooth surfaces.

[0095] 2. Testing Procedure: The test was conducted using a proppant chamber, in accordance with industry standard SY / T 6302-2019. The rock slab was placed within the proppant chamber, and proppant was filled between the slabs at a sand concentration of 4.88 kg / m². Closing pressure was gradually applied (from 10 MPa to 60 MPa). After stabilization at each pressure point, the proppant embedment depth (using a microscope or displacement sensor) and the corresponding proppant conductivity (using a 2% KCl solution) were measured and recorded.

[0096] Test results:

[0097]

[0098] Results analysis:

[0099] Embedding property: In soft coal and shale, the resin proppant of this invention exhibits minimal embedding property, with a significantly shallower embedding depth than that of silica sand. This is attributed to the inherent toughness and elasticity of the resin material, which allows for micro-deformation under closure pressure to increase the contact area and disperse stress, rather than being directly pressed into the rock like rigid silica sand. In hard sandstone, the embedding property of both is minimal.

[0100] Conductivity: Due to its shallow embedding depth, the proppant effectively maintains the fracture opening width, thus exhibiting significantly higher conductivity in coal and shale than in quartz sand. Especially in coal, its conductivity is more than twice that of quartz sand. This demonstrates that the proppant of this invention is highly suitable for embedding in severely damaged soft or brittle reservoirs (such as coalbed methane and shale gas), effectively maintaining high conductivity in fractures.

[0101] Example 7: Long-term flowability experiment of proppant

[0102] Objective: To evaluate the conductivity retention rate of the proppant of the present invention under long-term high closure pressure under simulated formation conditions, and to verify its long-term effectiveness.

[0103] Test method:

[0104] Sample: The proppant of the present invention prepared in Example 1 (20-40 mesh).

[0105] Test conditions: Following the modified API RP 61 long-term flow capacity test procedure. Proppant was added to the flow chamber at a concentration of 7.3 kg / m². A constant closure pressure of 60 MPa was applied, and the system temperature was raised to 90°C. A 2% KCl solution was used as the flow medium, and the test was conducted continuously for 250 hours. Flow capacity values ​​were recorded at regular intervals.

[0106] Test results:

[0107]

[0108] Results analysis:

[0109] Under prolonged conditions of 60 MPa high pressure and 90℃ high temperature, the proppant of this invention retains over 87.3% of its conductivity after 250 hours, demonstrating excellent long-term stability. The initial slight decrease is mainly due to the initial rearrangement and micro-embedding of particles; the subsequent curve flattens out, indicating that the proppant particles possess extremely high creep and fatigue resistance, with a very low breakage rate. This ensures that the fractures maintain high conductivity throughout the entire production lifecycle of the reservoir, which is crucial for maintaining long-term high and stable production of oil and gas wells.

[0110] In summary:

[0111] The ultra-low density proppant and its preparation method provided by this invention successfully solve the problems of existing proppants, such as high density, need for high-viscosity liquid to carry, difficulty in supporting at ultra-far ends, strong hydrophilicity that may inhibit oil phase flow, and severe embedding in soft formations leading to a sharp decline in conductivity.

[0112] This proppant, prepared using a pure thermosetting resin formulation and aqueous dispersion method, requires no inorganic fillers and possesses a comprehensive set of advantages, including ultra-low density (allowing for water / low-viscosity slickwater transport and ultra-far-end placement), ultra-high strength and toughness (low breakage rate under high closure pressure and minimal rock embedment), weak oleophilicity (facilitating oil phase penetration), excellent temperature resistance, and outstanding long-term conductivity retention. Experiments have shown that its suspension properties far exceed those of quartz sand and ceramsite, making it particularly suitable for low-displacement, small-scale, ultra-far-end fracturing stimulation of unconventional oil and gas reservoirs (shale, coalbed methane, etc.). It effectively reduces embedment damage and provides long-term stable high-conductivity channels, demonstrating significant market application potential.

[0113] All the devices selected in this application are general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0114] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0115] In the description of this invention, it should be noted that, based on the above-described preferred embodiments of the invention, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A clear or low slick water transportable ultra-low density high strength resin proppant, characterized in that, A resin composition comprising the following components in mass percentage: vinyl monomer 15-50wt%, acrylic ester monomer 5-10wt%, unsaturated resin 50-70wt%; The support agent has a bulk density of 0.6-0.8g / cm3, a specific gravity of 1.08-1.3g / cm3, a particle size of 12-140 mesh, and a breakage rate of less than 2wt% under a closed pressure of 90MPa; The vinyl monomer is one or more of styrene, divinylbenzene, and vinyltoluene; The acrylic ester monomer is one or more of methyl methacrylate, butyl methacrylate, dicyclopentadiene acrylate, and isobornyl acrylate.

2. A method for preparing a clear water or low slurry water transportable ultra-low density high strength resin proppant, characterized in that, The super-low-density high-strength resin proppant is carried by clear water or low-viscosity slick water. Further comprising the following steps: Step 1: preparing the oil phase: uniformly mixing the vinyl monomer, acrylic ester monomer, unsaturated resin, and curing agent to form a homogeneous resin mixture; Step 2: dispersing and granulating: adding the resin mixture obtained in Step 1 to the water phase containing a dispersant under stirring, and controlling the stirring speed and the amount of dispersant to disperse the resin mixture in the water phase to form spherical droplets with a particle size of 12-140 mesh; Step 3: curing and forming: adding a promoter to the system obtained in Step 2, and performing a curing reaction at a reaction temperature of 30-80℃ to form cured spherical particles; Step 4: post-treatment: after the reaction is completed, filtering, washing, and drying to obtain the super-low-density proppant product.

3. The method of claim 2, wherein the dispersant in Step 2 is one or more of gelatin, calcium phosphate, hydroxypropyl methylcellulose, sodium polyacrylate, and gum arabic.

4. The method of claim 3, wherein the stirring speed in Step 2 is 200-2000rpm.

5. The method of claim 2, wherein the curing agent in Step 1 is one or more of methyl ethyl ketone peroxide, cyclohexanone peroxide, dicumyl peroxide, tert-butyl peroxide-2-ethylhexanoate, and azobisisobutyronitrile.

6. The method of claim 5, wherein the amount of the curing agent added is 0.5-2wt% of the total mass of the resin composition.

7. The method of claim 6, wherein the promoter in Step 3 is one or more of cobalt naphthenate, cobalt isooctanoate, zinc isooctanoate, dimethylphenylamine derivatives, and acetylacetone metal salts.

8. The method of claim 7, wherein the promoter in Step 3 is one or more of cobalt naphthenate, cobalt isooctanoate, zinc isooctanoate, dimethylphenylamine derivatives, and acetylacetone metal salts. ​ ​ ​ ​ ​ The accelerator is added in an amount of 0.1-0.5 wt% of the total mass of the resin composition.

9. The method of claim 8, wherein the resin composition is prepared by adding the accelerator in an amount of 0.1-0.5 wt% of the total mass of the resin composition. In step 3, the rate and temperature of the curing reaction are controlled by adjusting the amount of accelerator added and the temperature of the water in the jacket of the reactor.

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