Epoxy resin plugging material and oil-based drilling fluid for improving formation pressure bearing capacity

Abstract

The invention discloses an epoxy resin plugging material and an oil-based drilling fluid for improving the pressure bearing capacity of a formation, and belongs to the technical field of oil and gas field drilling. The plugging agent used in the oil-based drilling fluid is an epoxy resin plugging material for improving the pressure bearing capacity of a formation, and the epoxy resin plugging material is prepared by a step-by-step method, and the synthetic raw materials include aniline substances containing ether bonds, epichlorohydrin, dihydroxy-substituted polybenzene substances, silicon carbide, and a silane coupling agent. The molar ratio of aniline substances containing ether bonds, dihydroxy-substituted polybenzene substances, and epichlorohydrin is approximately 1:1:2. The amount of the rigid material silicon carbide added is between 10-30g. The compressive strength of the epoxy resin plugging material of the present invention can reach 130-170MPa, and it can be used in oil-based drilling fluid as a pressure-bearing plugging material to reduce the leakage of drilling fluid and improve formation stability.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field drilling, and in particular to an epoxy resin plugging material and an oil-based drilling fluid for improving the pressure bearing capacity of formations. Background Art

[0002] Drilling fluid loss is a problem that has always attracted much attention in the petroleum engineering community. It can lead to complex situations and serious accidents underground, and also bring great harm to drilling engineering, oil and gas field development and reservoir protection. During the drilling process, after the drilling fluid enters the formation from the wellbore through the leakage channel, the construction personnel need to consume a large amount of mud and plugging materials to solve the problem of well leakage. If handled properly, the plugging consumption can be greatly reduced; but if handled improperly, it will lead to unpredictable losses in manpower, financial resources, time, etc., and may even cause underground accidents such as well collapse, stuck drill, blowout, etc. In severe cases, it may lead to problems such as wellbore scrapping and permanent reservoir damage.

[0003] The treatment of well leakage has always been an important topic in the field of drilling. Although a large number of conventional plugging agents have been used and have achieved certain application effects, it is often difficult to achieve the ideal plugging effect due to their insufficient pressure bearing capacity. Therefore, it is necessary to further develop and improve plugging materials with pressure bearing capacity to better deal with well leakage and improve the safety and efficiency of drilling operations.

[0004] The Chinese patent with publication number CN 115772392A proposes a high molecular oil-based cross-linking curing plugging agent for drilling fluid and its preparation method, wherein the plugging agent is obtained by mixing a modified first epoxy resin with a second epoxy resin to obtain a modified epoxy resin, the plugging agent comprises 60%-80% of the modified epoxy resin, 15%-30% of the curing agent, 1%-5% of the curing regulator, and 4%-10% of the reinforcing agent, and the compressive strength of the plugging agent is greater than 30MPa, thereby solving the problems of poor anti-pollution ability and poor plugging effect. However, its compressive strength still has room for improvement.

[0005] Epoxy resin molecules contain benzene rings, ether bonds, hydroxyl groups, epoxy groups and other groups, which give epoxy resin excellent properties. Among them, the benzene ring can improve the mechanical strength and heat resistance of epoxy resin, and the ether bond gives epoxy resin excellent chemical resistance, which makes epoxy resin an ideal plugging material. However, since most epoxy resins are made from bisphenol A, chain-type epoxy resins are synthesized, which have poor mechanical properties and cannot be effectively used for plugging. Compared with linear epoxy resins, branched epoxy resins have shown great improvements in mechanical properties, especially in terms of pressure bearing capacity. Therefore, branched epoxy resins are a better plugging material. Adding rigid material silicon carbide to the material can greatly improve its compressive resistance. Summary of the invention

[0006] In view of the problem that most current plugging materials still have poor plugging effects due to their insufficient pressure-bearing capacity, the present invention provides an epoxy resin plugging material and oil-based drilling fluid for improving the pressure-bearing capacity of formations. The epoxy resin plugging material can effectively improve the mechanical properties of the material, especially the pressure-bearing capacity, and can be used as a pressure-bearing plugging material in oil-based drilling fluid to reduce the loss of drilling fluid and improve formation stability.

[0007] To achieve the above purpose, the technical solution of the present invention is: an epoxy resin plugging material for improving the pressure bearing capacity of the formation. The raw materials of the epoxy resin plugging material include aniline substances containing ether bonds, epichlorohydrin, dihydroxy-substituted polybenzene substances, silicon carbide, and silane coupling agents. The epoxy resin plugging material is prepared by the following steps:

[0008] S1. Add ether-bonded aniline substances and methanol solution into a three-necked flask, equip it with a reflux condenser, drop epichlorohydrin under stirring, heat to 65-75°C and react for 4-6 hours, add triethylamine, lower the temperature to 40-60°C and stir for 3-5 hours, purify, and obtain epoxy-containing benzene substances;

[0009] S2. Add a mixture of dihydroxy-substituted polybenzene substances and sodium bisulfite dispersed in a 25% by mass aqueous ammonia solution into a three-necked flask, heat to 150-180° C., react for 12-15 hours under stirring, cool the reaction mixture to room temperature, add a NaOH aqueous solution to adjust the pH value to greater than 12, dry, and wash to obtain a polyamino-substituted polybenzene substance;

[0010] S3, placing silicon carbide in a vacuum drying oven at 80-110°C for 6-8h, accurately weighing the dried silicon carbide into a three-necked flask, adding toluene and a silane coupling agent, introducing nitrogen, heating to 80-90°C, stirring and reacting for 5-8h, ultrasonically dispersing, centrifuging at 10000r / min for 30min, washing with acetone, and placing in a vacuum drying oven at 100-120°C for 10-12h to obtain silicon carbide modified with a silane coupling agent;

[0011] S4. The epoxy-containing benzene substance prepared in S1 and the polyamino-substituted polybenzene substance prepared in S2 are mixed, and the temperature is raised to 130-160° C. to react for 4-7 hours to obtain a branched epoxy resin polymer. The branched epoxy resin polymer and the silane coupling agent-modified silicon carbide prepared in S3 are then mixed to prepare an epoxy resin plugging material for improving the pressure bearing capacity of the formation.

[0012] The aniline substance containing an ether bond in step S1 is one of 3-amino-4-(2-phenylbenzopyran-6-yloxy)anisole and 2-(2-naphthyloxy)aniline.

[0013] The dihydroxy-substituted polybenzene substance described in step S2 is one of 5,8-dihydroxy-10-methoxy-2-methyl-4H-naphtho[1,2-b]pyran-4-one, 5,8-dihydroxy-6,10-dimethoxy-2-methyl-4H-naphtho[1,2-b]pyran-4-one, 6-diphenyl-2,7-naphthalenediol, and 1,1′-(2,7-dihydroxy-1,6-naphthalenediyl)diethyl ketone.

[0014] In step S3, the silane coupling agent is one of 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane.

[0015] The molar ratio of the ether-bonded aniline substance, the dihydroxy-substituted polybenzene substance, and epichlorohydrin is approximately 1:1:2.

[0016] The added amount of the rigid material silicon carbide is between 5-30g.

[0017] In the present invention, the monomer material for synthesizing epoxy resin has a multi-benzene ring structure, which can improve the compression resistance and temperature resistance of epoxy resin, and the molecule is branched rather than linear during polymerization; it contains a large number of benzene ring structures, and is compounded with rigid materials, so that the formed material has good pressure bearing capacity. It can be used as a pressure-bearing plugging material in oil-based drilling fluid, reduce the loss of drilling fluid, and improve formation stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the partial structure of the branched epoxy resin polymer in Example 4. DETAILED DESCRIPTION

[0019] The technical solution 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 only 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 creative work are within the scope of protection of the present invention.

[0020] In this embodiment, unless otherwise specified, the parts are parts by weight.

[0021] 1. Preparation of epoxy resin plugging material to improve the pressure bearing capacity of the formation:

[0022] Example 1

[0023] (1) Synthesis of epoxy-containing benzene substances

[0024] 0.1 mol of 3-amino-4-(2-phenylbenzopyran-6-yloxy)anisole and 100 mL of methanol solution were added into a three-necked flask, equipped with a reflux condenser, and 0.2 mol of epichlorohydrin was added dropwise under stirring. The temperature was raised to 65°C and reacted for 6 hours. Then 30 mL of triethylamine was added, the temperature was lowered to 40°C and stirred for 5 hours, and purified to obtain epoxy-containing benzene substances.

[0025] (2) Synthesis of polyamino-substituted polyphenyls

[0026] A mixture of 0.1 mol 5,8-dihydroxy-10-methoxy-2-methyl-4H-naphtho[1,2-b]pyran-4-one and 0.25 mol sodium bisulfite dispersed in 80 mL of 25% ammonia solution was added into a three-necked flask, the temperature was raised to 150° C., and the mixture was reacted for 12 hours under stirring. After the reaction mixture was cooled to room temperature, a NaOH aqueous solution was added to adjust the pH value to greater than 12, and the mixture was dried and washed to obtain a polyamino-substituted polybenzene substance.

[0027] (3) Silicon carbide modified with silane coupling agent

[0028] The silicon carbide was placed in a vacuum drying oven at 80°C and dried for 8 hours. 10 g of the dried silicon carbide was accurately weighed into a three-necked flask, 70 mL of toluene and 0.3 g of 3-aminopropyltriethoxysilane were added thereto, nitrogen was introduced, the temperature was raised to 80°C and stirred for reaction for 7 hours, ultrasonically dispersed, high-speed centrifuged at 10000 r / min for 30 minutes, washed with acetone, and placed in a vacuum drying oven at 100°C and dried for 11 hours to obtain silicon carbide modified with a silane coupling agent.

[0029] (4) Preparation of epoxy resin plugging material to improve the pressure bearing capacity of the formation

[0030] The epoxy-containing benzene substance prepared in (1) and the polyamino-substituted polybenzene substance prepared in (2) are mixed, and the temperature is raised to 140° C. for reaction for 5 hours to obtain a branched epoxy resin polymer. The branched epoxy resin polymer and the silane coupling agent-modified silicon carbide prepared in (3) are then mixed to prepare an epoxy resin plugging material for improving the pressure bearing capacity of the formation.

[0031] Example 2

[0032] (1) Synthesis of epoxy-containing benzene substances

[0033] 0.1 mol of 3-amino-4-(2-phenylbenzopyran-6-yloxy)anisole and 100 mL of methanol solution were added into a three-necked flask, equipped with a reflux condenser, and 0.2 mol of epichlorohydrin was added dropwise under stirring. The temperature was raised to 70°C and reacted for 5 hours. Then, 30 mL of triethylamine was added, the temperature was lowered to 50°C and stirred for 4 hours, and purified to obtain epoxy-containing benzene substances.

[0034] (2) Synthesis of polyamino-substituted polyphenyls

[0035] A mixture of 0.1 mol 5,8-dihydroxy-6,10-dimethoxy-2-methyl-4H-naphtho[1,2-b]pyran-4-one and 0.25 mol sodium bisulfite dispersed in 80 mL of 25% ammonia solution was added into a three-necked flask, the temperature was raised to 160° C., and the mixture was reacted for 12 hours under stirring. After the reaction mixture was cooled to room temperature, a NaOH aqueous solution was added to adjust the pH value to greater than 12, the mixture was dried, and washed to obtain a polyamino-substituted polybenzene substance.

[0036] (3) Silicon carbide modified with silane coupling agent

[0037] The silicon carbide was placed in a vacuum drying oven at 100°C and dried for 8 hours. 15 g of the dried silicon carbide was accurately weighed into a three-necked flask, 105 mL of toluene and 0.45 g of 3-aminopropyltrimethoxysilane were added thereto, nitrogen was introduced, the temperature was raised to 90°C and stirred for reaction for 5 hours, ultrasonically dispersed, high-speed centrifuged at 10000 r / min for 30 minutes, washed with acetone, and placed in a vacuum drying oven at 110°C and dried for 10 hours to obtain silicon carbide modified with a silane coupling agent.

[0038] (4) Preparation of epoxy resin plugging material to improve the pressure bearing capacity of the formation

[0039] The epoxy-containing benzene substance prepared in (1) and the polyamino-substituted polybenzene substance prepared in (2) are mixed, and the temperature is raised to 150° C. for reaction for 5 hours to obtain a branched epoxy resin polymer. The branched epoxy resin polymer and the silane coupling agent-modified silicon carbide prepared in (3) are then mixed to prepare an epoxy resin plugging material for improving the pressure bearing capacity of the formation.

[0040] Example 3

[0041] (1) Synthesis of epoxy-containing benzene substances

[0042] 0.1 mol of 3-amino-4-(2-phenylbenzopyran-6-yloxy)anisole and 100 mL of methanol solution were added into a three-necked flask, equipped with a reflux condenser, and 0.2 mol of epichlorohydrin was added dropwise under stirring. The temperature was raised to 75°C and reacted for 4 hours. Then, 30 mL of triethylamine was added, the temperature was lowered to 45°C and stirred for 5 hours, and purified to obtain epoxy-containing benzene substances.

[0043] (2) Synthesis of polyamino-substituted polyphenyls

[0044] A mixture of 0.1 mol 6-diphenyl-2,7-naphthalene diol and 0.25 mol sodium bisulfite dispersed in 80 mL of 25% ammonia solution was added into a three-necked flask, the temperature was raised to 170° C., and the mixture was reacted for 13 hours under stirring. After the reaction mixture was cooled to room temperature, a NaOH aqueous solution was added to adjust the pH value to greater than 12, and the mixture was dried and washed to obtain a polyamino-substituted polyphenyl substance.

[0045] (3) Silicon carbide modified with silane coupling agent

[0046] The silicon carbide was placed in a vacuum drying oven at 110°C and dried for 6 hours. 20 g of the dried silicon carbide was accurately weighed into a three-necked flask, 140 mL of toluene and 0.6 g of 3-aminopropyltrimethoxysilane were added thereto, nitrogen was introduced, the temperature was raised to 90°C and stirred for reaction for 6 hours, ultrasonically dispersed, high-speed centrifuged at 10000 r / min for 30 minutes, washed with acetone, and placed in a vacuum drying oven at 100°C and dried for 12 hours to obtain silicon carbide modified with a silane coupling agent.

[0047] (4) Preparation of epoxy resin plugging material to improve the pressure bearing capacity of the formation

[0048] The epoxy-containing benzene substance prepared in (1) and the polyamino-substituted polybenzene substance prepared in (2) are mixed, and the temperature is raised to 150° C. for reaction for 6 hours to obtain a branched epoxy resin polymer. The branched epoxy resin polymer and the silane coupling agent-modified silicon carbide prepared in (3) are then mixed to prepare an epoxy resin plugging material for improving the pressure bearing capacity of the formation.

[0049] Example 4

[0050] (1) Synthesis of epoxy-containing benzene substances

[0051] 0.1 mol of 2-(2-naphthyloxy)aniline and 100 mL of methanol solution were added to a three-necked flask, equipped with a reflux condenser, and 0.2 mol of epichlorohydrin was added dropwise under stirring. The temperature was raised to 75°C and reacted for 4 hours. Then 30 mL of triethylamine was added, the temperature was lowered to 50°C and stirred for 5 hours. Purification was performed to obtain epoxy-containing benzene substances.

[0052] (2) Synthesis of polyamino-substituted polyphenyls

[0053] A mixture of 0.1 mol 6-diphenyl-2,7-naphthalene diol and 0.25 mol sodium bisulfite dispersed in 80 mL of 25% ammonia solution was added into a three-necked flask, the temperature was raised to 170° C., and the mixture was reacted for 13 hours under stirring. After the reaction mixture was cooled to room temperature, a NaOH aqueous solution was added to adjust the pH value to greater than 12, and the mixture was dried and washed to obtain a polyamino-substituted polyphenyl substance.

[0054] (3) Silicon carbide modified with silane coupling agent

[0055] The silicon carbide was placed in a vacuum drying oven at 110°C and dried for 6 hours. 25 g of the dried silicon carbide was accurately weighed into a three-necked flask, 175 mL of toluene and 0.75 g of 3-aminopropyltriethoxysilane were added thereto, nitrogen was introduced, the temperature was raised to 90°C and stirred for reaction for 6 hours, ultrasonically dispersed, high-speed centrifuged at 10000 r / min for 30 minutes, washed with acetone, and placed in a vacuum drying oven at 120°C and dried for 10 hours to obtain silicon carbide modified with a silane coupling agent.

[0056] (4) Preparation of epoxy resin plugging material to improve the pressure bearing capacity of the formation

[0057] The epoxy-containing benzene substance prepared in (1) and the polyamino-substituted polybenzene substance prepared in (2) are mixed, heated to 150° C. and reacted for 7 hours to obtain a branched epoxy resin polymer. The branched epoxy resin polymer and the silane coupling agent-modified silicon carbide prepared in (3) are then mixed to prepare an epoxy resin plugging material for improving the pressure bearing capacity of the formation.

[0058] Example 5

[0059] (1) Synthesis of epoxy-containing benzene substances

[0060] 0.1 mol of 2-(2-naphthyloxy)aniline and 100 mL of methanol solution were added into a three-necked flask, equipped with a reflux condenser, and 0.2 mol of epichlorohydrin was added dropwise under stirring. The temperature was raised to 75°C and reacted for 4 hours. After adding 30 mL of triethylamine, the temperature was lowered to 40°C and stirred for 5 hours. Purification was performed to obtain epoxy-containing benzene substances.

[0061] (2) Synthesis of polyamino-substituted polyphenyls

[0062] A mixture of 0.1 mol 1,1′-(2,7-dihydroxy-1,6-naphthalenediyl)diacetone and 0.25 mol sodium bisulfite dispersed in 80 mL of 25% ammonia solution was added into a three-necked flask, the temperature was raised to 180° C., and the mixture was reacted for 14 hours under stirring. After the reaction mixture was cooled to room temperature, a NaOH aqueous solution was added to adjust the pH value to greater than 12, and the mixture was dried and washed to obtain a polyamino-substituted polybenzene substance.

[0063] (3) Silicon carbide modified with silane coupling agent

[0064] The silicon carbide was placed in a vacuum drying oven at 90°C and dried for 8 hours. 30 g of the dried silicon carbide was accurately weighed into a three-necked flask, 210 mL of toluene and 0.9 g of 3-aminopropyltriethoxysilane were added thereto, nitrogen was introduced, the temperature was raised to 90°C and stirred for reaction for 6 hours, ultrasonically dispersed, high-speed centrifuged at 10000 r / min for 30 minutes, washed with acetone, and placed in a vacuum drying oven at 120°C and dried for 10 hours to obtain silicon carbide modified with a silane coupling agent.

[0065] (4) Preparation of epoxy resin plugging material to improve the pressure bearing capacity of the formation

[0066] The epoxy-containing benzene substance prepared in (1) and the polyamino-substituted polybenzene substance prepared in (2) are mixed, and the temperature is raised to 160° C. for reaction for 6 hours to obtain a branched epoxy resin polymer. The branched epoxy resin polymer and the silane coupling agent-modified silicon carbide prepared in (3) are then mixed to prepare an epoxy resin plugging material for improving the pressure bearing capacity of the formation.

[0067] Comparative Example

[0068] 50g of bisphenol A epoxy resin and 10g of polyethylene glycol 200 were added into a variable frequency high-speed mixer and stirred for 30 minutes. Then, 2.5g of curing agent Q-500 dicyandiamide, 0.3g of accelerator SH-A100 and 1.3g of stabilizer were added and stirred at 40°C for 6h to make the mixture evenly dispersed to obtain a bisphenol A epoxy resin plugging material.

[0069] 2. Preparation of oil-based drilling fluid

[0070] The present invention mainly describes the application of the pressure-bearing plugging branched epoxy resin by the following specific formula. Based on 340 parts by mass of base oil, the specific formula is: 3# white oil + primary emulsifier HIEMUL + auxiliary emulsifier HICOAT + wetting agent HIWET + organic soil SMGEL + calcium oxide + 20% calcium chloride solution + fluid loss reducer SMFLA-O + barite powder + epoxy resin plugging material for improving the pressure bearing capacity of the formation.

[0071] The specific preparation process is as follows: 340mL 3# white oil is added to a 1000mL stirring cup, and then 13g of primary emulsifier HIEMUL, 10g of auxiliary emulsifier HICOAT, and 5g of wetting agent HIWET are added, and stirred at high speed for 20min at 12000r / min, 14g of organic soil SMGEL is added, and stirred at high speed for 10min at 12000r / min, and then 23g of calcium oxide is added, and stirred at high speed for 10min at 12000r / min, and 60mL of calcium chloride aqueous solution (calcium chloride mass percentage concentration 20%) is slowly added, and stirred at high speed for 20min; then 24g of fluid loss reducer SMFLA-O is added and stirred at high speed for 20min, and 870g of barite is added and stirred at high speed for 30min to obtain the base slurry of oil-based drilling fluid. The prepared drilling fluid density is 2g / cm 3 .

[0072] 3. Performance Test

[0073] 1. Test of the compressive performance of epoxy resin plugging materials to improve the pressure bearing capacity of the formation

[0074] The final products of Example 1, Example 2, Example 3, Example 4 and Example 5 were sampled for compressive strength test, and three groups of samples were taken for each material. The compression test refers to ASTM D6641, and two strain gauges, one vertical and one horizontal, are pasted on the front and back surfaces of the test piece respectively, so as to obtain the average compressive strain and Poisson's ratio of the two surfaces of the test piece. An Instron 5882 testing machine (range 100kN) is used, and a combined loading compression fixture (CLC) is used to apply a compressive load to the test piece, and the data obtained from the test are averaged. Table 1 shows the compressive strength record table of Example 1, Example 2, Example 3, Example 4, Example 5 and the comparative example.

[0075] From the results shown in Table 1, it can be seen that compared with the bisphenol A epoxy resin with a chain molecular structure, the branched epoxy resin has a better pressure bearing capacity, and as the amount of rigid material particles increases, its pressure resistance also increases.

[0076] Table 1 Epoxy resin compression performance test

[0077]

[0078] 2. Wedge-shaped 3mm-4mm crack plugging test

[0079] Evaluation criteria for plugging cracks: The main considerations for plugging cracks are whether the plugging material can quickly form a dense and effective filling layer in the cracks, whether the filling layer can withstand greater pressure and the cracks will no longer extend, thereby increasing the pressure-bearing capacity of the cracks, and the concentration of rigid particles and the compatibility of the cracks.

[0080] According to the above slurry preparation, 19 parts of the same base slurry were prepared, and 0 parts, 1 part, 4 parts, and 7 parts of Example 1, Example 2, Example 3, Example 4, Example 5, and Comparative Example were added respectively, so as to prepare 19 parts of oil-based drilling fluids with different addition amounts of epoxy resin plugging materials and bisphenol A epoxy resin plugging materials for improving the bearing capacity of formations, and the base slurry without plugging materials was used as a blank experimental group. In order to further illustrate the effect of the epoxy resin plugging materials for improving the bearing capacity of formations of the present invention, wedge plate crack plugging experiments were carried out on oil-based drilling fluids with different amounts of plugging materials added.

[0081] According to Table 2, after adding plugging material to the base slurry, wedge-shaped 3mm-4mm cracks can be plugged. As the amount of plugging material added increases, the plugging effect improves. The formula with the best plugging effect is: base slurry + 7% Example 4.

[0082] Table 2 Results of wedge-shaped 3mm-4mm crack plugging test

[0083]

[0084]

[0085]

[0086] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. An epoxy resin plugging material for improving the pressure bearing capacity of the formation, characterized in that: The raw materials of the epoxy resin plugging material are ether-bonded aniline substances, epichlorohydrin, dihydroxy-substituted polybenzene substances, silicon carbide, and silane coupling agent. The molar ratio of the ether-bonded aniline substances, dihydroxy-substituted polybenzene substances, and epichlorohydrin is 1:1:

2. The epoxy resin plugging material is prepared by the following steps: S1. Add ether-bonded aniline substances and methanol solution into a three-necked flask, equip it with a reflux condenser, drop epichlorohydrin under stirring, heat to 65-75°C and react for 4-6 hours, add triethylamine, lower the temperature to 40-60°C and stir for 3-5 hours, purify, and obtain epoxy-containing benzene substances; S2. Add a mixture of dihydroxy-substituted polybenzene substances and sodium bisulfite dispersed in a 25% by mass aqueous ammonia solution into a three-necked flask, heat to 150-180° C., react for 12-15 hours under stirring, cool the reaction mixture to room temperature, add a NaOH aqueous solution to adjust the pH value to greater than 12, dry, and wash to obtain a polyamino-substituted polybenzene substance; S3, placing silicon carbide in a vacuum drying oven at 80-110°C for 6-8h, accurately weighing the dried silicon carbide into a three-necked flask, adding toluene and a silane coupling agent, introducing nitrogen, heating to 80-90°C, stirring and reacting for 5-8h, ultrasonically dispersing, centrifuging at 10000r / min for 30min, washing with acetone, and placing in a vacuum drying oven at 100-120°C for 10-12h to obtain silicon carbide modified with a silane coupling agent; S4, mixing the epoxy-containing benzene substance prepared in S1 and the polyamino-substituted polybenzene substance prepared in S2, heating to 130-160° C. for reaction for 4-7 hours to obtain a branched epoxy resin polymer, and then mixing the branched epoxy resin polymer with the silane coupling agent-modified silicon carbide prepared in S3 to prepare an epoxy resin plugging material for improving the pressure bearing capacity of the formation; The silane coupling agent is one of 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; the ether bond-containing aniline substance is one of 3-amino-4-(2-phenylbenzopyran-6-yloxy)anisole and 2-(2-naphthyloxy)aniline; the dihydroxy substituted polybenzene substance is one of 5,8-dihydroxy-10-methoxy-2-methyl-4H-naphtho[1,2-b]pyran-4-one, 5,8-dihydroxy-6,10-dimethoxy-2-methyl-4H-naphtho[1,2-b]pyran-4-one, 6-diphenyl-2,7-naphthalenediol and 1,1′-(2,7-dihydroxy-1,6-naphthalenediyl)diethyl ketone; and the amount of silicon carbide used is 5-30g.

2. The epoxy resin plugging material for improving the pressure bearing capacity of the formation according to claim 1, characterized in that The epoxy resin is branched.

3. An oil-based drilling fluid, characterized in that: The drilling fluid is added with the epoxy resin plugging material for improving the pressure bearing capacity of the formation as claimed in claim 1.

4. The oil-based drilling fluid according to claim 3, characterized in that: The drilling fluid comprises the following components: base oil, primary emulsifier, auxiliary emulsifier, wetting agent, organic soil, calcium oxide, water phase, fluid loss reducer, plugging material and weighting agent.

5. The oil-based drilling fluid according to claim 4, characterized in that: The base oil is 3# white oil, the main emulsifier is HIEMUL, the auxiliary emulsifier is HICOAT, the wetting agent is HIWET, the organic soil is SMGEL, the aqueous phase is 20% calcium chloride solution, the fluid loss reducer is SMFLA-O, the plugging material is the epoxy resin for improving the bearing capacity of the formation according to claim 1, and the weighting agent is barite powder.

6. The oil-based drilling fluid according to claim 5, characterized in that: The drilling fluid comprises the following components by weight: 340 parts of 3# white oil, 12-13 parts of primary emulsifier HIEMUL, 8-10 parts of auxiliary emulsifier HICOAT, 4-5 parts of wetting agent HIWET, 12-14 parts of organic soil SMGEL, 20-23 parts of calcium oxide, 20-24 parts of fluid loss reducer SMFLA-O, 60 parts of 20% calcium chloride solution, 4-28 parts of epoxy resin for improving the pressure bearing capacity of the formation, 660-870 parts of barite powder, and the drilling fluid density is 1.8-2.0 g / cm 3 .

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