A degradable polyglycolic acid-based conical temporary plugging ball and its preparation method

Abstract

The present invention discloses a degradable polyglycolic acid-based conical temporary plugging ball, which has the morphology of a combination of a hemisphere and a cone through a flat end, and has an outer shell and an inner core structure; wherein the shell raw materials include polyglycolic acid, polyvinyl alcohol, vinyl silane and methacrylic acid; the inner core raw materials include polyglycolic acid, cellulose ester, a degradation promoter, a plasticizer, a filler and an antioxidant. The temporary plugging ball of the present invention has excellent plugging performance and good degradability, can effectively plug cracks in oil and gas field fracturing operations, improve fracturing efficiency, and has a wide applicable temperature range, pressure resistance, long pressure stabilization time, and can self-degrade after the operation is completed, which can effectively reduce pollution to the formation and the complexity of subsequent operations, reduce production costs, and effectively improve the development efficiency and economic benefits of oil and gas fields; and the preparation method involved is simple and controllable, which can meet the needs of different formation conditions and fracturing processes.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas extraction, and particularly relates to a degradable polyglycolic acid-based conical temporary plugging ball and a preparation method thereof. Background Art

[0002] As a key means to improve the efficiency of oil and gas field extraction, fracturing technology is widely used in the production process of oil and gas wells. During the fracturing process, temporary plugging balls are an important auxiliary material used to temporarily seal the cracks that have been opened so that the subsequent fracturing fluid can be diverted to other unfractured formation areas. This diversion technology can effectively improve fracturing efficiency and increase oil and gas production. However, existing temporary plugging ball materials generally have some problems: traditional temporary plugging ball materials mainly include polymers, resins, waxes, etc. These materials are difficult to degrade after the fracturing operation is completed and often require additional measures to remove them, which not only increases operating costs, but may also cause unnecessary damage to the formation. In addition, the degradation rate and mechanical strength of these materials are often difficult to meet the complex and changeable fracturing process requirements.

[0003] Patent CN102199420A discloses a water-soluble temporary plugging agent, the main components of which are guar gum and aluminum oxide. The two will undergo a cross-linking reaction under formation conditions to form a rubber plug with a pressure resistance of about 30 MPa, achieving a plugging effect. However, it needs to be broken and unblocked after the fracturing diversion operation. Patent CN103409121A discloses a water-soluble fracturing diversion temporary plugging agent, the core components of which are plant starch, polymer, expander and curing agent; the temporary plugging agent has good solubility, strong adhesion and excellent flowback performance. However, the water-soluble temporary plugging agent also has problems such as incomplete ablation and low pressure resistance. Patent application CN104418999A discloses a temporary plugging agent of a degradable copolyester nanocomposite material, the main component of which is formed by in-situ copolymerization of polyethylene terephthalate (PET) esterification intermediate and inorganic nanoparticles. This material is only suitable for reservoirs above 80°C.

[0004] In recent years, polyglycolic acid (PGA), as a degradable material, has gradually attracted attention due to its excellent biodegradability and environmental friendliness. At present, the industry generally believes that the spherical structure makes the temporary plugging balls easier to move in the fracturing fluid. The symmetry of the sphere can be set at any angle and helps to evenly distribute the pressure on the surface of the sphere. Therefore, the existing polyglycolic acid temporary plugging balls are mostly spherical structures. However, the existing process ignores the deformation and expansion of the blasthole caused by proppant grinding and fracturing fluid erosion. During the plugging process, the irregular shape of the blasthole cannot be completely filled, which may lead to loose plugging and affect the plugging effect. The molding of non-spherical temporary plugging balls is more complicated than that of spherical ones, and the pressure bearing requirements are high. At the same time, they need to have sufficient flexibility to adapt to different blasthole diameters and shapes. In addition, polyglycolic acid temporary plugging balls are mostly high-temperature degradable materials, with high requirements for reservoir temperature and a small temperature application range. They have certain limitations in practical applications. Summary of the Invention

[0005] The main purpose of the present invention is to address the problems and shortcomings of the existing technology and provide a conical PGA temporary plugging ball with excellent sealing performance and good degradability, which can effectively seal cracks in oil and gas field fracturing operations and improve fracturing efficiency. It has a wide applicable temperature range, pressure resistance, and long pressure stabilization time. It can self-degrade after the operation is completed (degradation rate reaches 100%), which can effectively reduce pollution to the formation and the complexity of subsequent operations, reduce production costs, and improve the development efficiency and economic benefits of oil and gas fields. The preparation method involved is simple and controllable, and can meet the needs of different formation conditions and fracturing processes.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A degradable polyglycolic acid-based conical temporary plugging ball has a morphology of a hemisphere and a cone combined through the planar ends of the two, and has an outer shell and an inner core structure; the shell material includes polyglycolic acid, polyvinyl alcohol, vinyl silane and methacrylic acid; the inner core material includes polyglycolic acid, cellulose ester, a degradation accelerator, a plasticizer, a filler and an antioxidant.

[0008] Furthermore, the shell material comprises the following components, in their respective mass percentages: 30-40 wt% polyglycolic acid, 30-45 wt% polyvinyl alcohol, 8-12% vinyl silane, and 15-18% methacrylic acid. The present invention combines polyglycolic acid and polyvinyl alcohol to achieve a balance between biodegradability and good mechanical strength, meeting environmental requirements while ensuring material durability. Furthermore, the introduction of vinyl silane and methacrylic acid as crosslinking agents enhances the material's crosslinking density and effectively improves the shell's heat and chemical resistance, enabling the temporary plugging ball to remain stable in complex underground environments.

[0009] Furthermore, the components and their mass percentages in the inner core material include: polyglycolic acid 60-75%, cellulose ester 15-30%, degradation accelerator 0.5-6%, plasticizer 5-15%, filler 5-15%, and antioxidant 2-4%.

[0010] In the above scheme, the polyglycolic acid is a white or light yellow powder with a molecular weight of 300,000-500,000 Da, an active ingredient content of ≥96%, and a particle size of 50-100 μm. The polyvinyl alcohol is a white or slightly creamy yellow powder with a molecular weight of 200,000-400,000 Da, a particle size of 50-100 μm, and an active ingredient content of ≥95%. These polyglycolic acid and polyvinyl alcohol exhibit excellent mechanical strength, toughness, and formability, capable of withstanding high stresses and resisting breakage. They can be easily molded into desired shapes and sizes through methods such as injection molding and extrusion. They also exhibit excellent chemical stability, maintain structural stability over a wide pH range, are resistant to acidic and alkaline environments, and maintain stable performance over extended periods in underground environments.

[0011] In the above scheme, the cellulose ester can be selected from one or a mixture of cellulose acetate, cellulose acetate butyrate, etc., which can effectively increase the compressibility and elasticity of the temporary blocking ball, help the temporary blocking ball to better adapt to pores and cracks under high pressure environment, and improve the blocking effect.

[0012] In the above solution, the degradation accelerator comprises bio-based polyurethane.

[0013] Preferably, the degradation accelerator comprises bio-based polyurethane and amylase; wherein the mass ratio of bio-based polyurethane to amylase is 1:(0.05-0.1).

[0014] Furthermore, the bio-based polyurethane is polycaprolactone-based polyurethane.

[0015] Furthermore, the molecular weight of the bio-based polyurethane is 5000 Da-10000 Da.

[0016] In the above scheme, the bio-based polyurethane introduced into the degradation accelerator can improve the mechanical properties of PGA, making it more stable during the degradation process and preventing premature breakage. It also helps maintain the integrity of the material during the initial degradation phase, and subsequently accelerates the degradation of the entire composite material through the degradation of the polyurethane. Furthermore, the introduction of polyurethane can increase the material's sensitivity to hydrolysis, making PGA more susceptible to water molecules, thereby accelerating its degradation at low temperatures. Furthermore, the bio-based polyurethane can physically bind to PGA, creating an environment more conducive to amylase catalysis. Amylase, in turn, accelerates the hydrolysis of PGA. By designing a combination of materials with different degradation rates, multi-stage degradation can be achieved. This effectively addresses the problem of prolonged degradation time for PGA and other fillers at low temperatures, while also regulating their degradation time at high temperatures. By promoting polymer chain scission through different mechanisms, the degradation rate of the temporary plugging ball can be controlled under specific conditions (such as temperature, pressure, and pH).

[0017] In the above solution, the plasticizer can be one or more of dioctyl sebacate, diethylhexyl phthalate (DEHP), and adipic acid esters. The selected plasticizer is used to increase the plasticity of the polyglycolic acid material, making it easier to process into the desired shape and size during the manufacturing process. It also adjusts the hardness of the temporary plugging ball, ensuring that the temporary plugging ball is neither too hard to set nor too soft to effectively seal.

[0018] In the above scheme, the filler can be selected from one of calcium carbonate, boron carbide, silicon dioxide, etc., which mainly improves the heat resistance, pressure resistance and mechanical strength of the temporary blocking ball, while improving its fluidity and dispersibility. It itself will not react chemically with other raw materials.

[0019] In the above scheme, the antioxidant can be selected from one of 2,6-di-tert-butyl-p-cresol (BHT), silane coupling agent, ethylenediaminetetraacetic acid (EDTA), etc., which is mainly used to improve the antioxidant properties of the material, especially to improve the thermal stability of the material, so that it is not easy to age in a high temperature environment, and enhance its stability during storage and use.

[0020] Furthermore, in the conical temporary blocking ball, the plane of the hemispherical part is connected to the plane of the conical part, and the shapes and sizes are matched.

[0021] Furthermore, the degradable polyglycolic acid-based conical temporary blocking ball includes a closed outer shell and a core filled inside the outer shell, and the outer wall surfaces of the core are all in contact with the inner wall surface of the outer shell; the outer shell includes a hollow hemispherical shell and a hollow conical shell, and the open end of the hemispherical shell is connected to the end opening of the conical shell; the hemispherical shell is connected to the core inside the conical shell, and the shape of the core is consistent with the shape of the corresponding shell.

[0022] Furthermore, the diameter of the hemispherical plane is preferably r=18-32 mm; and the length of the tapered generatrix is ​​L=1.2r-1.5r.

[0023] The preparation method of the above-mentioned degradable conical polyglycolic acid conical temporary plugging ball comprises the following steps:

[0024] 1) uniformly mixing polyglycolic acid, cellulose derivative, degradation accelerator, plasticizer, filler, and antioxidant weighed in a certain proportion; heating the resulting mixture under stirring until it becomes fluid to obtain an inner core mixture;

[0025] 2) Under pressure, the inner core mixture is injected into a conical spherical inner core mold, the pressure is maintained and the mixture is naturally cooled, and then water-cooled to room temperature; the inner core is demoulded to obtain the inner core;

[0026] 3) uniformly mixing polyglycolic acid, polyvinyl alcohol, vinyl silane, and methacrylic acid weighed in a certain proportion, and heating the mixture into a uniform liquid to obtain a shell mixture;

[0027] 4) fixing the inner core in the conical spherical shell mold by fixing pins, wherein the outer surface of the inner core and the inner cavity wall of the conical spherical shell mold form the shell casting space; injecting the shell mixture (without pressurization), cooling naturally, and water cooling to room temperature; demolding, and drying to obtain the conical temporary plugging ball.

[0028] In the above scheme, the heating temperature used in step 1) is 215-240°C.

[0029] In the above scheme, the pressure used in step 2) is 60-80 MPa.

[0030] In the above solution, the pressure-maintaining and natural cooling time in step 2) is 5-8 minutes.

[0031] In the above scheme, the water cooling step in step 2) is controlled to be 30-40 minutes.

[0032] In the above scheme, the heating temperature in step 3) is 215-240°C.

[0033] In the above scheme, the natural cooling time in step 4) is 5-8 minutes.

[0034] In the above scheme, the water cooling step in step 4) is controlled to be 30-40 minutes.

[0035] In the above solution, the temperature used in the drying step is 40-60° C. to remove excess solvent and moisture while solidifying the shell.

[0036] Furthermore, the conical spherical inner core mold and the conical spherical outer shell mold include a hemispherical cavity and a conical cavity, wherein the circumference of the open end of the hemispherical cavity is connected to the circumference of the open end of the conical cavity, and the sizes are matched.

[0037] Furthermore, the conical spherical shell mold is consistent in shape with the conical spherical inner core mold, and the shell mold is a detachable mold. The entire mold consists of two parts. When casting the shell, the temporary blocking ball inner core is fixed to the center of the mold through the built-in positioning pin.

[0038] Furthermore, the fixing pin is cylindrical, with a diameter of 0.5-1 mm and a length of 1-2 mm.

[0039] Furthermore, the inner wall of the conical spherical shell mold is provided with a plurality of fixing pins, wherein the inner bottom of the hemispherical cavity is provided with a fixing pin, and at least two fixing pins are provided at intervals in the circumferential direction on the inner wall of the conical cavity.

[0040] Furthermore, the degradable polyglycolic acid conical temporary plugging ball prepared according to the above scheme has vents after demolding, can adapt to the temporary plugging needs of 60-180℃ reservoirs, has a maximum pressure resistance of 70MPa, a pressure stabilization time of >120min, and can self-degrade after the operation is completed, with a degradation rate of 100%.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The inner core and shell of the temporary plugging ball of the present invention are both made of degradable materials. By optimizing the formula of the inner core and shell, the problems of PGA-based materials such as high brittleness and easy fracture under high pressure and high stress environments are effectively improved. The problem of the slow dissolution rate of polyglycolic acid materials at low temperatures can also be effectively solved, which greatly increases the application temperature range of the PGA temporary plugging ball reservoir.

[0043] (2) Compared with existing bullet-shaped, truncated cone-shaped, rugby-shaped and other irregular temporary plugging balls, the conical design of the present invention is easier to position in the blasthole, avoiding rolling or movement problems, and providing better stability, especially in inclined or vertical wellbores, helping to maintain the position of the temporary plugging ball. At the same time, because the diameter of the conical part gradually increases with the generatrix, it can adapt to blastholes of various diameters and different degrees of deformation, fit more closely to the well wall, and improve the plugging efficiency. At the same time, the conical structure helps to guide the fluid to disperse in all directions, thereby improving the plugging effect.

[0044] (3) Compared with traditional polyglycolic acid temporary blocking balls, the modified polyglycolic acid temporary blocking balls of the present invention have a wider applicable temperature range. By changing the raw material ratio, temporary blocking balls suitable for a temperature range of 60-180°C can be formed, and the compressive strength can reach 60 MPa. At the same time, the preparation process of the temporary blocking balls is simple, and they are easy to mass-produce, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a diagram of the temporary blocking ball structure;

[0046] Figure 2 Schematic diagram of the mold structure used in the embodiment, wherein the left figure is a schematic diagram of the shell mold structure, and 1 in the figure is a positioning pin; the right figure is a schematic diagram of the fixation of the inner core in the shell mold.

[0047] Figure 3 Schematic diagram of the structure of the positioning pin. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0049] The methods described in the examples are conventional methods unless otherwise specified; the reagents used are commercially available unless otherwise specified.

[0050] In the following examples, the bio-based polyurethane is polycaprolactone-based polyurethane (CLPU) with a molecular weight of 5000 Da to 10000 Da, and is produced by BASF SE.

[0051] The molecular weight of the cellulose acetate used is 100,000-150,000 Da, and the molecular weight of the cellulose acetate butyrate is 100,000-200,000 Da, and they are provided by Jiangsu Plus Biotechnology Co., Ltd.

[0052] Example 1

[0053] A degradable polyglycolic acid-based conical temporary plugging ball (schematic diagram see Figure 1 ), the core components and their mass percentages are: polyglycolic acid 60g (molecular weight 400000Da), cellulose acetate 15g, bio-based polyurethane 2.7g, amylase 0.27g, dioctyl sebacate 5g, diethylhexyl phthalate (DEHP) 5g, silicon dioxide 10g, ethylenediaminetetraacetic acid (EDTA) 2g; the shell components and their mass percentages are: polyglycolic acid 30g (molecular weight 400000Da), polyvinyl alcohol 45g (molecular weight 300000Da), vinyl silane 10g, methacrylic acid 15g;

[0054] The preparation method of the temporary blocking ball comprises the following steps:

[0055] The polyglycolic acid, cellulose acetate, bio-based polyurethane, dioctyl sebacate, diethylhexyl phthalate (DEHP), silicon dioxide, and ethylenediaminetetraacetic acid weighed in proportion are mixed uniformly; the resulting mixture is heated to 220° C. and mixed thoroughly using a mixer while heating to ensure uniformity of the mixture, thereby obtaining an inner core mixture (insulation);

[0056] A conical spherical inner core mold with a hemispherical inner diameter r = 17 mm and a busbar length = 20.4 mm is selected. A layer of lubricating oil is applied to the inner surface of the mold and the mold is preheated to above 200°C. Under a pressure of 70 MPa, the obtained inner core mixture is injected into the preheated No. 1 conical spherical inner core mold. The pressure is maintained and the mold is naturally cooled for 5-8 minutes. Then, the mold is water-cooled with a circulating coolant (such as water). After the temperature is lowered to room temperature after 30 minutes, the mold is opened and the inner core is taken out. Its appearance and quality are inspected to ensure that the inner core surface is smooth and free of defects before subsequent processing.

[0057] (3) Mixing polyglycolic acid, polyvinyl alcohol, vinyl silane, and methacrylic acid weighed in proportion and heating to 220±5° C. to dissolve and mix uniformly to obtain a shell mixture;

[0058] (4) Select a shell mold with a hemispherical inner diameter r = 18 mm and a busbar length = 21.6 mm (see Figure 2 ), fix the inner core at the center of the outer shell mold by a cylindrical positioning pin 1, and inject the outer shell mixture into the annular space of the inner cavity of the irregular conical spherical outer shell mold to form an outer shell around the inner core; after natural cooling for 5 minutes, use a circulating coolant (such as water) to water-cool the mold and reduce the temperature to room temperature within 30-40 minutes;

[0059] (5) demoulding and drying at a constant temperature of 40°C; thus, the degradable polyglycolic acid-based conical temporary plugging ball is obtained, and three vent holes are provided at the positions of the fixing pins around the spherical surface.

[0060] Example 2

[0061] A degradable polyglycolic acid-based conical temporary plugging ball, the preparation method of which is substantially the same as that of Example 1, except that:

[0062] The core components and their mass percentages are: polyglycolic acid 67g (molecular weight 400000Da), cellulose acetate butyrate 15g, bio-based polyurethane 3.8g, amylase 0.2g, adipate 5g, boron carbide 7g, 2,6-di-tert-butyl-p-cresol (BHT) 2g;

[0063] The shell components and their mass percentages are: polyglycolic acid 34g (molecular weight 400000Da), polyvinyl alcohol 40g (molecular weight 400000Da), vinyl silane 8g, methacrylic acid 18g

[0064] Example 3

[0065] A degradable polyglycolic acid-based conical temporary plugging ball, the preparation method of which is substantially the same as that of Example 1, except that:

[0066] The core components and their mass percentages are: polyglycolic acid 70g (molecular weight 300000Da), cellulose acetate 10g, cellulose acetate butyrate 5g, bio-based polyurethane 1.8g, amylase 0.2g, diethylhexyl phthalate (DEHP) 3g, adipate 2g, boron carbide 5g, 2,6-di-tert-butyl-p-cresol (BHT) 3g;

[0067] The shell components and their mass percentages are: polyglycolic acid 40g (molecular weight 300000Da), polyvinyl alcohol 30g (molecular weight 400000Da), vinyl silane 12g, and methacrylic acid 18g.

[0068] Comparative Example 1

[0069] A degradable polyglycolic acid-based conical temporary plugging ball, the preparation method of which is substantially the same as that of Example 1, except that:

[0070] The core components and their mass percentages are: polyglycolic acid 70g (molecular weight 300000Da), cellulose nitrate 5g, cellulose phosphate 10g, bio-based polyurethane 1.8g, amylase 0.2g, diethylhexyl phthalate (DEHP) 3g, adipate 2g, boron carbide 5g, 2,6-di-tert-butyl-p-cresol (BHT) 3g;

[0071] The shell components and their mass percentages are: polyglycolic acid 40g (molecular weight 300000Da), polyvinyl alcohol 30g (molecular weight 400000Da), vinyl silane 12g, and methacrylic acid 18g.

[0072] Comparative Example 2

[0073] A degradable polyglycolic acid-based conical temporary plugging ball, the preparation method of which is substantially the same as that of Example 1, except that:

[0074] The core components and their mass percentages are: polyglycolic acid 70g (molecular weight 300000Da), cellulose acetate 10g, cellulose acetate butyrate 5g, diethylhexyl phthalate (DEHP) 3g, adipate 2g, boron carbide 5g, 2,6-di-tert-butyl-p-cresol (BHT) 3g;

[0075] The shell components and their mass percentages are: polyglycolic acid 40g (molecular weight 300000Da), polyvinyl alcohol 30g (molecular weight 400000Da), vinyl silane 12g, and methacrylic acid 18g.

[0076] Comparative Example 3

[0077] A degradable polyglycolic acid-based conical temporary plugging ball, the preparation method of which is substantially the same as that of Example 1, except that:

[0078] The core components and their mass percentages are: polyvinyl alcohol 70g (molecular weight 50000Da), cellulose acetate 10g, cellulose acetate butyrate 5g, bio-based polyurethane 1.8g, amylase 0.2g, diethylhexyl phthalate (DEHP) 3g, adipate 2g, boron carbide 5g, 2,6-di-tert-butyl-p-cresol (BHT) 3g;

[0079] The shell components and their mass percentages are: polyglycolic acid 40g (molecular weight 300000Da), polyvinyl alcohol 30g (molecular weight 400000Da), vinyl silane 12g, and methacrylic acid 18g.

[0080] Comparative Example 4

[0081] A degradable polyglycolic acid-based conical temporary plugging ball, the preparation method of which is substantially the same as that of Example 1, except that:

[0082] The core components and their mass percentages are: polyglycolic acid 70g (molecular weight 300000Da), cellulose acetate 10g, cellulose acetate butyrate 5g, bio-based polyurethane 1.8g, amylase 0.2g, diethylhexyl phthalate (DEHP) 3g, adipate 2g, boron carbide 5g, 2,6-di-tert-butyl-p-cresol (BHT) 3g;

[0083] The shell components and their mass percentages are: polyglycolic acid 40g (molecular weight 50000Da), polyvinyl alcohol 30g (molecular weight 50000Da), vinyl silane 12g, and methacrylic acid 18g.

[0084] Comparative Example 5

[0085] A degradable polyglycolic acid-based conical temporary plugging ball, the preparation method of which is substantially the same as that of Example 1, except that:

[0086] The core components and their mass percentages are: polyglycolic acid 70g (molecular weight 300000Da), cellulose acetate 10g, cellulose acetate butyrate 5g, amylase 2g, diethylhexyl phthalate (DEHP) 3g, adipate 2g, boron carbide 5g, 2,6-di-tert-butyl-p-cresol (BHT) 3g;

[0087] The shell components and their mass percentages are: polyglycolic acid 40g (molecular weight 300000Da), polyvinyl alcohol 30g (molecular weight 400000Da), vinyl silane 12g, and methacrylic acid 18g.

[0088] The temporary plugging balls obtained in the embodiment and the comparative example were tested for key indicators such as pressure resistance, temperature resistance and solubility, and the results are shown in Table 1.

[0089] Table 1 Performance test results of temporary plugging agents obtained in Examples and Comparative Examples Experimental results

[0090]

[0091]

[0092] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the above embodiments describe the present invention in detail, relevant technical personnel in the field should understand that the present invention can be modified or replaced by equivalents, but any modifications and partial replacements that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A degradable polyglycolic acid-based conical temporary blocking ball, characterized in that: It has a shape of a hemisphere and a cone with a flat end, and has a shell and an inner core structure; the shell material includes polyglycolic acid, polyvinyl alcohol, vinyl silane and methacrylic acid; the inner core material includes polyglycolic acid, cellulose ester, degradation accelerator, plasticizer, filler and antioxidant; The degradation accelerator is two of bio-based polyurethane and amylase; The antioxidant is one of 2,6-di-tert-butyl-p-cresol and ethylenediaminetetraacetic acid.

2. The degradable polyglycolic acid-based conical temporary blocking ball according to claim 1, characterized in that: The shell raw material comprises the following components and their weight percentages: 30-40 wt % of polyglycolic acid, 30-45 wt % of polyvinyl alcohol, 8-12 wt % of vinyl silane, and 15-18 wt % of methacrylic acid.

3. The degradable polyglycolic acid-based conical temporary blocking ball according to claim 1, characterized in that: Ester 15-30%, degradation accelerator 0.5-6%, plasticizer 5-15%, filler 5-15%, antioxidant 2-4%.

4. The degradable polyglycolic acid-based conical temporary blocking ball according to claim 1, characterized in that: The cellulose ester is one of cellulose acetate and cellulose acetate butyrate, or a mixture of the two.

5. The degradable polyglycolic acid-based conical temporary blocking ball according to claim 1, characterized in that: The plasticizer is one or more of dioctyl sebacate, diethylhexyl phthalate, and adipic acid ester.

6. The degradable polyglycolic acid-based conical temporary blocking ball according to claim 1, characterized in that: The filler is one of calcium carbonate, boron carbide and silicon dioxide.

7. The method for preparing the degradable conical polyglycolic acid conical temporary plugging ball according to any one of claims 1 to 6, characterized in that: The steps include: 1) uniformly mixing the polyglycolic acid, cellulose derivative, degradation accelerator, plasticizer, filler, and antioxidant weighed in proportion; heating the resulting mixture under stirring until it becomes fluid to obtain an inner core mixture; 2) Under pressure, the inner core mixture is injected into the conical spherical inner core mold, the pressure is maintained and the mixture is naturally cooled, and then water-cooled to room temperature; the inner core is demoulded to obtain the inner core; 3) Evenly mixing the polyglycolic acid, polyvinyl alcohol, vinyl silane, and methacrylic acid weighed according to the proportion, and heating the mixture into a uniform liquid to obtain a shell mixture; 4) fixing the inner core in the conical spherical shell mold by fixing pins, wherein the outer surface of the inner core and the inner cavity wall of the conical spherical shell mold form the shell casting space; injecting the shell mixture, cooling naturally, and water cooling to room temperature; demolding, and drying to obtain the conical temporary plugging ball.

8. The preparation method according to claim 7, characterized in that The heating temperature used in step 1) is 215-240°C; the heating temperature in step 3) is 215-240°C.

9. The preparation method according to claim 7, characterized in that The water cooling step in step 2) lasts for 30-40 minutes; and the water cooling step in step 4) lasts for 30-40 minutes.

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