Degradable while-drilling plugging agent for protecting hydrocarbon reservoir and preparation method of degradable while-drilling plugging agent

Abstract

The invention discloses a degradable while-drilling plugging agent for protecting a hydrocarbon reservoir, which comprises the following components in parts by weight: 0.5-1 part of calcium beta-hydroxy beta-methyl butyrate, 5-8 parts of calcium carbonate, 0.05-0.1 part of a silane coupling agent, 5-15 parts of thermosetting resin and 2-3 parts of a fiber material. The beta-hydroxy beta-methyl calcium butyrate is added into the plugging agent, so that the plugging effect in the oil and gas exploitation process is greatly improved. Besides, degradation of the plugging agent can be realized through processes such as steam injection, a miner can control the degradation rate of the plugging agent according to production requirements, and construction is simple, convenient and safe.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas, and specifically relates to a degradable lost circulation material for protecting oil and gas reservoirs during drilling and its preparation method. Background Technique

[0002] The ultimate goal of drilling and completion is to drill through the reservoir and form a channel for oil and gas flow, and establish a good production relationship for oil and gas wells. Damage to oil and gas reservoirs will greatly affect the productivity of oil and gas wells, mainly manifested as a decrease in the permeability of oil and gas reservoirs. In recent years, domestic and foreign scholars have conducted extensive and in-depth research on the mechanism of reservoir damage and have obtained some recognized conclusions:

[0003] ① Solid particles in external fluids such as drilling fluids and completion fluids and loose particles originally in the reservoir migrate under external force, directly blocking the pores and throats of the rock;

[0004] ② Moisture in external fluids causes clay minerals in the reservoir to hydrate and swell, reducing the pores and throats and hindering the flow of oil and gas;

[0005] ③ Physical and chemical reactions occur between external fluids and reservoir fluids, generating insoluble inorganic salts and organic matter precipitates or forming high-viscosity emulsions, blocking the pores of reservoir rocks and increasing the resistance to oil and gas flow;

[0006] ④ Filtrate in external fluids invades the reservoir, causing wettability reversal of the reservoir, reducing the relative permeability of oil and gas, and affecting the oil recovery rate.

[0007] The traditional shielding temporary plugging technology for protecting oil and gas reservoirs selects appropriate particle sizes of oil and gas reservoir protection additives according to the pore throat distribution characteristics of the reservoir to match the pore throat diameter distribution of the oil and gas reservoir, achieving effective temporary plugging. The key to the shielding temporary plugging technology for protecting oil and gas reservoirs is that there are three solid particles in the drilling and completion fluid: bridging particles with sufficient quantity and capable of stably bridging on the pore throats of the oil reservoir; filling particles smaller than the bridging particles; highly dispersed fine particles capable of deforming under pressure difference and high temperature, namely denatured particles. Bridging particles are generally selected as light and ultrafine calcium carbonate, filling particles are small particles in the drilling fluid, and denatured particles are selected from materials that soften at formation temperature. Generally, sulfonated asphalt is used, and oil-soluble resins can also be selected. The three particles act simultaneously to form a dense shielding ring to prevent harmful solids and filtrate from further contaminating the oil and gas reservoir, thereby eliminating the damage to the oil and gas reservoir caused by the increase in soaking time. After completion, the shielding ring is removed to restore the permeability of the reservoir, achieving the purpose of effectively protecting the reservoir. The completion method generally uses perforation.

[0008] Chinese Patent CN116445138B discloses a plugging agent and its preparation method and application. The plugging agent mainly consists of diatomite, hydrophobic nano-silica, lipophilic flaky molybdenum disulfide, and lipophilic calcium carbonate. When used in oil-based drilling fluids, it has good dispersibility and stability, and also has good plugging effect and anti-friction and anti-wear performance, but this plugging agent cannot be degraded. Chinese Patent CN116285917A discloses a high-temperature-resistant plugging isolation fluid. Through the synergistic effect of weighting agents, suspension stabilizers, plugging agents, flushing agents, and defoaming agents, it can ensure a plugging strength of 1 - 5 MPa in the range of 30°C to 160°C, but it also cannot be degraded and is difficult to deal with the problem of self-degradation after plugging for a period of time in some cases.

[0009] In summary, it is crucial to develop a degradable lost circulation material during drilling with a simple construction method and effective reservoir protection. Summary of the Invention

[0010] In view of the deficiencies of the prior art and actual needs, the present invention proposes a degradable lost circulation material during drilling for protecting oil and gas reservoirs and its preparation method. The present invention adds calcium β-hydroxy-β-methylbutyrate to the plugging agent, greatly improving the plugging effect during oil and gas exploitation.

[0011] To achieve the above object, the present invention adopts the following technical solutions:

[0012] In the first aspect, the present invention provides a degradable lost circulation material during drilling for protecting oil and gas reservoirs. Calculated by weight, the plugging agent includes the following components: 0.5 - 1 part of calcium β-hydroxy-β-methylbutyrate, 5 - 8 parts of calcium carbonate, 0.05 - 0.1 part of silane coupling agent, 5 - 15 parts of thermosetting resin, and 2 - 3 parts of fiber material.

[0013] In one or more embodiments, the calcium β-hydroxy-β-methylbutyrate consists of 80 - 90 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 160 - 500 mesh and 10 - 20 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 500 - 600 mesh.

[0014] In one or more embodiments, the calcium carbonate consists of 30 - 50 wt% of calcium carbonate with a particle size of 80 - 300 mesh and 50 - 70 wt% of calcium carbonate with a particle size of 300 - 600 mesh.

[0015] In one or more embodiments, the silane coupling agent is at least one of vinyltrichlorosilane and vinyltrimethoxysilane.

[0016] In one or more embodiments, the thermosetting resin is at least one of melamine formaldehyde resin, phenolic resin, or epoxy resin.

[0017] In one or more embodiments, the fiber material is one or more of wood fiber, glass fiber, polypropylene fiber, and polyester fiber, and the length of the fiber material is 2 - 4 mm.

[0018] In one or more embodiments, the plugging agent is degraded by a hot steam spraying method.

[0019] Second, the present invention provides a method for preparing the degradable lost circulation plugging agent while drilling, and the method includes the following steps:

[0020] S1. Add calcium β-hydroxy-β-methylbutyrate, calcium carbonate, and silane coupling agent into a mixing tank, and uniformly mix at a rotation speed of 200 - 300 r / min for 5 - 10 min; then add the thermosetting resin into it, and uniformly mix at a rotation speed of 400 - 600 r / min for 2 - 3 min;

[0021] S2. Heat the above mixture to 50 - 60 °C, continuously stir and react for 20 - 30 min, and add the fiber material during the stirring process. After the stirring ends, the degradable lost circulation plugging agent while drilling is obtained.

[0022] Third, the present invention provides the application of any of the above-mentioned degradable lost circulation plugging agents while drilling in petroleum drilling lost circulation plugging.

[0023] Fourth, the present invention provides a drilling fluid, and the drilling fluid contains any of the degradable lost circulation plugging agents while drilling of the present invention, and the concentration of the plugging agent in the drilling fluid is 10 - 30 g / L.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The preparation method of the plugging agent of the present invention is simple to operate. The prepared plugging agent is uniformly dispersed and has stable performance in water-based drilling fluid. The particle size distribution range of the solid particles in the plugging agent is wide, and pores and fractures with a size of 400 mD - 100 D can be effectively plugged through a suitable particle size combination, having a good oil and gas reservoir protection effect.

[0026] (2) The degradation of the plugging agent of the present invention can be achieved by processes such as injecting steam, which can meet the use conditions of 80 - 150 °C. The producer can control the degradation rate of the plugging agent according to production requirements, and the construction is simple, convenient, and safe. Specific Embodiments

[0027] Calcium β-hydroxy-β-methylbutyrate, also known as β-Hydroxyβ-Methylbutyrate Calcium, abbreviated as HMBCa, is a common dietary supplement that is believed to promote muscle growth and recovery. The mechanism of action of HMBCa is not fully understood, but studies have shown that it may act by reducing muscle breakdown and promoting muscle protein synthesis. In addition, HMBCa can also increase the body's sensitivity to insulin and promote the utilization of glucose by muscles, thereby improving muscle energy metabolism.

[0028] The inventors have found that using calcium β-hydroxy-β-methylbutyrate, which is generally used in food, as a component of a lost circulation material can improve the temporary plugging effect of the lost circulation material on the basis of specific particle sizes and specific addition amounts.

[0029] Specifically, the lost circulation material described in the present invention further comprises calcium carbonate, a silane coupling agent, a thermosetting resin, and a fiber material.

[0030] Preferably, by weight, the lost circulation material described in the present invention comprises 0.5 to 1 part of calcium β-hydroxy-β-methylbutyrate, 5 to 8 parts of calcium carbonate, 0.05 to 0.1 part of a silane coupling agent, 5 to 15 parts of a thermosetting resin, and 2 to 3 parts of a fiber material.

[0031] In the present invention, the silane coupling agent is at least one of vinyltrichlorosilane and vinyltrimethoxysilane.

[0032] In the present invention, the thermosetting resin is at least one of melamine formaldehyde resin, phenolic resin, or epoxy resin.

[0033] In the present invention, the fiber material is one or more of wood fiber, glass fiber, polypropylene fiber, and polyester fiber, and the length of the fiber material is 2 to 4 mm.

[0034] Example

[0035] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0036] Before further describing the specific implementation manners of the present invention, it should be understood that the protection scope of the present invention is not limited to the specific implementation manners described below; it should also be understood that the terms used in the embodiments of the present invention are for the purpose of describing specific implementation manners and are not intended to limit the protection scope of the present invention.

[0037] When numerical ranges are given in the examples, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains.

[0038] For those technical or conditions not specified in the examples, they shall be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. For the reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through regular channels.

[0039] Regarding the addition amounts, contents and concentrations of various substances in the examples, unless otherwise specified, the percentage contents mentioned therein all refer to mass percentage contents.

[0040] The calcium β-hydroxy-β-methylbutyrate consists of 80 - 90 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 160 - 500 mesh and 10 - 20 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 500 - 600 mesh.

[0041] In one or more embodiments, the calcium carbonate consists of 30 - 50 wt% of calcium carbonate with a particle size of 80 - 300 mesh and 50 - 70 wt% of calcium carbonate with a particle size of 300 - 600 mesh.

[0042] Example 1:

[0043] A degradable lost circulation material for protecting oil and gas reservoirs while drilling, by weight, the lost circulation material comprises the following components: 0.8 part of calcium β-hydroxy-β-methylbutyrate, 6 parts of calcium carbonate, 0.07 part of silane coupling agent, 10 parts of thermosetting resin and 2.5 parts of fiber material. Among them, the calcium β-hydroxy-β-methylbutyrate consists of 85 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 160 - 500 mesh and 15 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 500 - 600 mesh; the calcium carbonate consists of 40 wt% of calcium carbonate with a particle size of 80 - 300 mesh and 60 wt% of calcium carbonate with a particle size of 300 - 600 mesh; the silane coupling agent is a composition of vinyltrichlorosilane and vinyltrimethoxysilane in a mass ratio of 1:1; the thermosetting resin is melamine formaldehyde resin; the fiber material is polypropylene fiber, and the length of the fiber material is 3 mm.

[0044] The preparation method of the above-mentioned degradable lost circulation material for protecting oil and gas reservoirs while drilling comprises the following steps:

[0045] S1. Add calcium β-hydroxy-β-methylbutyrate, calcium carbonate and silane coupling agent into a mixing tank, and mix them evenly at a rotation speed of 250 r / min for 8 min; then add the thermosetting resin into it, and mix evenly at a rotation speed of 500 r / min for 3 min;

[0046] S2. Heat the above mixture to 55 °C, continuously stir and react for 25 min, and add the fiber material during the stirring process. After the stirring ends, the degradable lost circulation material A is obtained.

[0047] Example 2:

[0048] A degradable lost circulation material for protecting oil and gas reservoirs, in parts by weight, the lost circulation material comprises the following components: 0.5 part of calcium β-hydroxy-β-methylbutyrate, 5 parts of calcium carbonate, 0.05 part of silane coupling agent, 5 parts of thermosetting resin and 2 parts of fiber material. Among them, the calcium β-hydroxy-β-methylbutyrate is composed of 80 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 160 - 500 mesh and 20 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 500 - 600 mesh; the calcium carbonate is composed of 30 wt% of calcium carbonate with a particle size of 80 - 300 mesh and 70 wt% of calcium carbonate with a particle size of 300 - 600 mesh; the silane coupling agent is vinyltrichlorosilane; the thermosetting resin is phenolic resin; the fiber material is wood fiber, and the length of the fiber material is 2 mm.

[0049] The preparation method of the degradable lost circulation material, the method comprises the following steps:

[0050] S1. Add calcium β-hydroxy-β-methylbutyrate, calcium carbonate and silane coupling agent into a mixing tank, and mix them evenly at a rotation speed of 200 r / min for 10 min; then add the thermosetting resin into it, and mix evenly at a rotation speed of 400 r / min for 2 min;

[0051] S2. Heat the above mixture to 50 °C, continuously stir and react for 30 min, and add the fiber material during the stirring process. After the stirring ends, the degradable lost circulation material B is obtained.

[0052] Example 3:

[0053] A degradable lost circulation material for protecting oil and gas reservoirs. By weight, the lost circulation material comprises the following components: 1 part of calcium β-hydroxy-β-methylbutyrate, 8 parts of calcium carbonate, 0.1 part of silane coupling agent, 15 parts of thermosetting resin, and 3 parts of fiber material. Among them, the calcium β-hydroxy-β-methylbutyrate consists of 90wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 160 - 500 mesh and 10wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 500 - 600 mesh; the calcium carbonate consists of 50wt% of calcium carbonate with a particle size of 80 - 300 mesh and 50wt% of calcium carbonate with a particle size of 300 - 600 mesh; the silane coupling agent is vinyltrimethoxysilane; the thermosetting resin is epoxy resin; the fiber material is polyester fiber, and the length of the fiber material is 4mm.

[0054] The preparation method of the degradable lost circulation material while drilling, the method comprises the following steps:

[0055] S1. Add calcium β-hydroxy-β-methylbutyrate, calcium carbonate, and silane coupling agent into a mixing tank, and mix evenly at a rotation speed of 300r / min for 5min; then add the thermosetting resin into it, and then mix evenly at a rotation speed of 600r / min for 2min;

[0056] S2. Heat the above mixture to 60°C, continuously stir and react for 20min, and add the fiber material during the stirring process. After the stirring ends, the degradable lost circulation material C is obtained.

[0057] Comparative Example 1: Lack of calcium β-hydroxy-β-methylbutyrate

[0058] A lost circulation material, whose components are basically the same as those in Example 1, the difference is that it lacks calcium β-hydroxy-β-methylbutyrate.

[0059] Its preparation method is basically the same as that in Example 1, the difference is that calcium β-hydroxy-β-methylbutyrate is not added in step S1.

[0060] Comparative Example 2: Different composition of calcium β-hydroxy-β-methylbutyrate

[0061] A lost circulation material, whose components are basically the same as those in Example 1, the difference is that the calcium β-hydroxy-β-methylbutyrate consists of 100wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 160 - 500 mesh.

[0062] Its preparation method is the same as that in Example 1.

[0063] Comparative Example 3: Different composition of calcium β-hydroxy-β-methylbutyrate

[0064] A plugging agent, whose composition is basically the same as that of Example 1, except that the calcium β-hydroxy-β-methylbutyrate consists of 100 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 500 - 600 mesh.

[0065] Its preparation method is the same as that of Example 1.

[0066] Comparative Example 4: Different composition of calcium β-hydroxy-β-methylbutyrate

[0067] A plugging agent, whose composition is basically the same as that of Example 1, except that the calcium β-hydroxy-β-methylbutyrate consists of 20 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 160 - 500 mesh and 80 wt% of calcium β-hydroxy-β-methylbutyrate with a particle size of 500 - 600 mesh.

[0068] Its preparation method is the same as that of Example 1.

[0069] Comparative Example 5: Different addition ratios of calcium β-hydroxy-β-methylbutyrate and calcium carbonate

[0070] A plugging agent, whose composition is basically the same as that of Example 1, except that: by weight, the calcium β-hydroxy-β-methylbutyrate is 1 part and the calcium carbonate is 3 parts.

[0071] Its preparation method is the same as that of Example 1.

[0072] Test Example 1: Evaluation of plugging effect

[0073] In this test example, the plugging agents prepared in Examples 1 - 3 and Comparative Examples 1 - 5 were evaluated for their plugging effect, and the results are shown in Table 1.

[0074] It was measured with a threaded cup - lid type permeability plugging instrument, and the high - temperature and high - pressure filtration loss was measured according to Appendix J of GB / T 16783.1—2014 "Field Testing of Drilling Fluids - Part 1: Water - based Drilling Fluids", and the permeability plugging filtration loss and static filtration rate (leakage rate) were calculated.

[0075] Table 1 Test results of plugging effect

[0076]

[0077] From the above results, it can be seen that the permeability plugging filtration loss of the lost - circulation - while - drilling agents prepared in Examples 1 - 3 is smaller, while that of Comparative Examples 1 - 5 is larger; the leakage rate of the lost - circulation - while - drilling agents prepared in Examples 1 - 3 is smaller, while that of Comparative Examples 1 - 5 is larger. In summary, the lost - circulation - while - drilling agent prepared by the present invention has a better lost - circulation - while - drilling effect.

[0078] Test Example 2: Degradation performance test

[0079] Place the lost circulation agents described in Examples 1 - 3 and Comparative Examples 1 - 5 into an aging tank, heat - roll them at a high temperature of 120 °C in a roller furnace for 6 h, and spray each lost circulation agent with 300 °C hot steam. Observe whether there are phenomena such as damage to the packer structure. The results are shown in Table 2.

[0080] As can be seen from the results in Table 2, the lost circulation agents prepared in the examples and comparative examples were damaged after being sprayed with high - temperature steam, indicating that the raw materials used in the present invention can be effectively degraded under high - temperature steam. In addition, the lost circulation agents described in Examples 1 - 3 have a faster degradation rate than those described in Comparative Examples 1 - 5 under high - temperature steam, which can save time and reduce costs.

[0081] Table 2 Test results of degradation performance

[0082] Leak plugging agent Status after steam spraying Rate of breakage Example 1 Breakage Relatively fast Example 2 Breakage Relatively fast Example 3 Breakage Relatively fast Comparative example 1 Breakage Relatively slow Comparative example 2 Breakage Relatively slow Comparative example 3 Breakage Relatively slow Comparative example 4 Breakage Relatively slow Comparative example 5 Breakage Relatively slow

[0083] Detection Example 3: Compatibility test with each drilling fluid system

[0084] The test process is as follows: The experimental temperature is 100 °C. Use a ZNN - D6 six - speed rotary viscometer to measure the viscosity and shear force of each sample. The test process and calculation method refer to GB / T 16783.1 - 2014 "Petroleum and natural gas industries - Drilling fluid field testing - Part 1: Water - based drilling fluids - Section 6". The compatibility test results for the following (1) - (4) are shown in Table 3.

[0085] (1) Add 10 g of degradable lost circulation agent A (Example 1) to 1000 mL of polymer drilling fluid system (containing 40 g of bentonite, 1 g of KPAM, 2 g of XC, 15 g of PAC - LV, 20 g of SMP - I, 20 g of SAS, and 200 g of BaSO 4 ) and stir for 1 hour.

[0086] (2) Add 20 g of degradable lost circulation agent B (Example 2) to 1000 mL of potassium chloride polymer drilling fluid system (containing 40 g of bentonite, 1 g of XC, 1 g of KPAM, 20 g of PAC - LV, 30 g of SMP - I, 30 g of SAS, 20 g of SN resin, 70 g of KCl, 5 g of NaOH, and 260 g of BaSO 4 ) and stir for 1 hour.

[0087] (3) Add 30 g of degradable lost circulation agent C (Example 3) to 1000 mL of organic salt drilling fluid system (containing 3 g of Na 2 CO 3 , 20 g of sepiolite powder, 1 g of coating agent, 10 g of Redul, 1 g of XC, 30 g of white asphalt, 20 g of polyalcohol, 300 g of sodium formate, and 400 g of BaSO 4 ) and stir for 1 hour

[0088] (4) Add 20 g of degradable lost circulation material A (Example 1) to a 1000 mL under-saturated brine drilling fluid system (containing 10 g of bentonite, 5 g of soda ash, 4 g of NaOH, 1 g of encapsulant, 70 g of KCl, 200 g of NaCl, 20 g of PAC-LV, 3 g of XC, 20 g of white asphalt and 450 g of BaSO 4 ) and stir for 1 hour.

[0089] Table 3 Compatibility test results

[0090]

[0091] As shown in Table 3, after adding the lost circulation material provided by the present invention, there is no substantial difference in its rheological properties (apparent viscosity, plastic viscosity, dynamic shear force, initial shear force, final shear force) in drilling fluids of different systems, indicating that the lost circulation material has good compatibility with water-based drilling fluids.

[0092] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A degradable plugging agent for protecting oil and gas layers, characterized in that: The plugging agent comprises the following components in parts by weight: 0.5-1 parts of calcium β-hydroxy β-methylbutyrate, 5-8 parts of calcium carbonate, 0.05-0.1 parts of silane coupling agent, 5-15 parts of thermosetting resin and 2-3 parts of fiber material.

2. The degradable plugging agent while drilling according to claim 1, characterized in that: The beta-hydroxy beta-methyl calcium butyrate is composed of 80-90 wt % of beta-hydroxy beta-methyl calcium butyrate with a particle size of 160-500 meshes and 10-20 wt % of beta-hydroxy beta-methyl calcium butyrate with a particle size of 500-600 meshes.

3. The degradable plugging agent while drilling according to claim 1, characterized in that: The calcium carbonate is composed of 30-50 wt % of calcium carbonate with a particle size of 80-300 meshes and 50-70 wt % of calcium carbonate with a particle size of 300-600 meshes.

4. The degradable plugging agent while drilling according to claim 1, characterized in that: The silane coupling agent is at least one of vinyl trichlorosilane and vinyl trimethoxysilane.

5. The degradable plugging agent while drilling according to claim 1, characterized in that: The thermosetting resin is at least one of melamine formaldehyde resin, phenolic resin or epoxy resin.

6. The degradable plugging agent while drilling according to claim 1, characterized in that: The fiber material is one or more of wood fiber, glass fiber, polypropylene fiber, and polyester fiber, and the length of the fiber material is 2 to 4 mm.

7. The degradable plugging agent while drilling according to claim 1, characterized in that: The plugging agent is degraded by a hot steam spraying method.

8. The method for preparing the degradable while-drilling plugging agent according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: S1. Add calcium β-hydroxy β-methylbutyrate, calcium carbonate and silane coupling agent into a mixing tank, and mix them evenly at a speed of 200 to 300 r / min for 5 to 10 minutes; then add the thermosetting resin, and mix them evenly at a speed of 400 to 600 r / min for 2 to 3 minutes; S2, heating the mixture to 50-60° C., stirring and reacting for 20-30 min, adding the fiber material during the stirring process, and obtaining the degradable while-drilling plugging agent after the stirring is completed.

9. Use of the degradable while-drilling plugging agent according to any one of claims 1 to 7 in plugging leaks in oil drilling.

10. A drilling fluid, characterized in that: The drilling fluid contains the degradable while-drilling plugging agent according to any one of claims 1 to 7, and the concentration of the plugging agent in the drilling fluid is 10 to 30 g / L.

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