Strength stabilizer, temporary plugging agent and preparation method and application of temporary plugging agent

Abstract

The invention discloses a strength stabilizer, a temporary plugging agent and a preparation method and application of the temporary plugging agent. The strength stabilizer is modified aerogel, the modified aerogel is modified by dodecyl trimethoxy silane, gamma-glycidyl ether oxypropyl trimethoxy silane and sodium glycinate, the strength stabilizer is used in the temporary plugging agent, carboxylate radicals of the modified aerogel can be subjected to complex reaction with calcium ions in calcium silicate salt, and the curing capacity of the temporary plugging agent is remarkably improved. The prepared temporary plugging agent has excellent temperature resistance, high pressure-bearing plugging capacity and plugging removal capacity, and the purposes of well leakage prevention and control and reservoir protection are achieved.

Description

Technical Field

[0001] This invention relates to the field of oil drilling fluids, specifically to a strength stabilizer, a temporary plugging agent, and their preparation methods and applications. Background Technology

[0002] Currently, oil-based drilling fluids are widely used due to their excellent lubricity and high-temperature stability. However, when drilling into complex oil and gas reservoirs, multi-scale fractures and even fracture-vuggy structures are developed, resulting in frequent well leakage during drilling and completion. The success rate of temporary plugging is generally less than 40%. Repeated plugging operations lead to a large amount of working fluid and plugging material invading the reservoir, inducing severe reservoir damage.

[0003] For oil-based drilling fluid losses, the main methods used are bridging and polymer plugging. Conventional bridging plugging typically uses nutshell-based materials, with a success rate of around 30% on the first attempt. Polymer plugging uses polymer materials that are prone to degradation under high temperatures and have poor long-term pressure stability. In addition, cement plugging, as a traditional plugging method, is widely used in deep and ultra-deep well drilling projects.

[0004] However, existing cement-based plugging materials exhibit significantly delayed and weakened hydration reactions in oil-bearing environments, leading to difficulties in consolidation or insufficient consolidation strength, with pressure resistance typically below 3 MPa. Furthermore, the acid solubility of cement-based plugging materials is less than 30%, failing to effectively restore oil and gas migration pathways and causing permanent damage to the reservoir. Overall, existing cement-based plugging materials suffer from low sealing strength and difficulty in unplugging in oil-based drilling fluid wells, severely hindering the efficient development of complex oil and gas reservoirs, and resulting in high costs for subsequent reservoir stimulation and production enhancement measures. Therefore, there is an urgent need to develop a novel temporary plugging material with strong adaptability, good biodegradability, and effective resistance to oil-based drilling fluid contamination, achieving the integrated goal of "well leakage prevention and efficient unplugging." Summary of the Invention

[0005] The purpose of this invention is to provide a strength stabilizer, a temporary plugging agent, and their preparation method and application, so as to solve the technical problems of poor pressure-bearing sealing ability and high difficulty in unblocking existing technologies.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of this invention provides a strength stabilizer, wherein the strength stabilizer is a modified aerogel, and the structural formula of the modified aerogel is as follows:

[0007] In the formula, A represents aerogel.

[0008] The modified aerogel was obtained by modification with dodecyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane and sodium glycinate.

[0009] According to the strength stabilizer of the present invention, preferably, the aerogel is a nanocellulose aerogel.

[0010] A second aspect of the present invention provides a method for preparing the strength stabilizer described above, wherein the preparation method includes the following steps: The aerogel was added to the first solvent, followed by dodecyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane. The pH was adjusted to 4, and the mixture was heated to carry out the first reaction. After the reaction was completed, the intermediate was obtained by freeze drying. The intermediate was added to the second solvent, sodium glycinate was added, the pH was adjusted to 9, and the mixture was stirred at room temperature to carry out the second reaction. After the reaction was completed, the modified aerogel was obtained by freeze drying.

[0011] According to the method for preparing the strength stabilizer of the present invention, preferably, the mass ratio of the aerogel, dodecyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane and sodium glycinate is 15:(3-5):(1-3):(1.5-3.5).

[0012] According to the method for preparing the strength stabilizer of the present invention, preferably, the first solvent is a mixture of ethanol and water. More preferably, the volume ratio of ethanol to water is 90:10 to 95:5.

[0013] According to the preparation method of the strength stabilizer of the present invention, preferably, the second solvent is a mixed solvent of dichloromethane and water. More preferably, the volume ratio of dichloromethane to water is 70:30. In the preparation method of the strength stabilizer of the present invention, the amounts of the first solvent and the second solvent are the amounts of conventional reaction solvents, sufficient to ensure that the raw materials are mixed uniformly and react smoothly; the present invention does not limit this.

[0014] According to the method for preparing the strength stabilizer of the present invention, preferably, acetic acid is used to adjust the pH to 4, and triethylamine is used to adjust the pH to 9.

[0015] According to the method for preparing the strength stabilizer of the present invention, preferably, the temperature of the first reaction is 50-70°C and the time is 6-12 hours; The second reaction was carried out at room temperature for 8-12 hours.

[0016] A third aspect of the present invention provides a temporary plugging agent, wherein the temporary plugging agent comprises, by weight, the following components: 10-40 parts curing agent, 5-10 parts retarder, 20-30 parts filter aid, 10-20 parts or more of the strength stabilizer provided in the first aspect, 0.5-1 part dispersant and 3-5 parts water; The curing agent is selected from at least one of tricalcium silicate, dicalcium silicate, monocalcium silicate, anhydrous calcium sulfoaluminate, and calcium sulfate. The retarder is selected from at least one of sodium pyrophosphate, citric acid, boric acid, and sodium hexametaphosphate; The filter aid is selected from at least one of diatomaceous earth, basalt fiber, and sepiolite; The dispersant is selected from polyacrylate and polyetheramine modified styrene-maleic anhydride copolymer.

[0017] The components in the temporary plugging agent provided by this invention work synergistically: the curing agent provides the main solidification structure, the retarder regulates the rate of the solidification reaction, the filter aid promotes filtration loss and accelerates the formation of a dense temporary plugging layer, the strength stabilizer adsorbs the oil-water mixture and enhances the plugging effect of the temporary plugging layer, and the dispersant improves the dispersibility of solid particles in water and prevents particle aggregation and sedimentation; finally, the overall performance of the temporary plugging agent material is achieved through the reasonable compounding of the components.

[0018] According to the present invention, the temporary plugging agent preferably comprises, by weight, 20-30 parts of curing agent, 8-12 parts of retarder, 23-27 parts of filter aid, 13-17 parts of strength stabilizer, 0.6-0.8 parts of dispersant and 3-5 parts of water.

[0019] A fourth aspect of the present invention provides a method for preparing the above-described temporary plugging agent, wherein the preparation includes the following steps: The curing agent, retarder, filter aid, strength stabilizer and dispersant are mixed evenly to obtain a solid mixture; then water is added and stirred evenly to obtain the temporary plugging agent.

[0020] The fifth aspect of the present invention provides the application of the above-described temporary plugging agent in deep or ultra-deep oil and gas reservoirs.

[0021] In reservoir plugging operations using oil-based drilling fluids, this temporary plugging agent can form a sealing layer with a pressure-bearing capacity of over 20 MPa and a compressive strength as high as 19.6 MPa in an environment of 180℃. In reservoir plugging operations using oil-based drilling fluids, this temporary plugging agent, when mixed with oil-based drilling fluid at a 7:3 mass ratio, can still solidify to form a sealing layer with a pressure-bearing capacity ≥ 4.4 MPa.

[0022] The temporary plugging agent of this invention incorporates modified aerogel as a strength stabilizer, adsorbing the oil-water mixture in oil-based drilling fluids. Simultaneously, the carboxyl groups of the modified aerogel undergo a complexation reaction with calcium ions in calcium silicate salts, stabilizing the solidified structure. This temporary plugging agent exhibits excellent temperature resistance, high pressure-bearing plugging capacity, and rapid curing and bonding characteristics. It can quickly form a dense, solidified slug plugging layer and possesses high acid solubility (acid solubility >90%), effectively reducing reservoir damage. Furthermore, the preparation process of this temporary plugging agent is simple and inexpensive. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the modified aerogel structure.

[0024] Figure 2 It is an aerogel modification route.

[0025] Figure 3 This is a test diagram of the crack pressure-bearing sealing capacity of temporary plugging agent E6.

[0026] Figure 4 This is a graph showing the compressive strength test results of temporary plugging agent E6. Detailed Implementation

[0027] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0028] The main technical solution of this invention is to provide a modified aerogel, which is used as a strength stabilizer in a temporary plugging agent. It can adsorb the oil-water mixture in oil-based drilling fluid. At the same time, the carboxyl group of the modified aerogel will undergo a complexation reaction with the calcium ions in the calcium silicate salt, stabilizing the solidified structure.

[0029] Among them, the modified aerogel structure is as follows Figure 1 As shown, its modification route is as follows: Figure 2 As shown, the aerogel first undergoes a first reaction with dodecyltrimethoxysilane and γ-glycidyloxypropyltrimethoxysilane, and then reacts with sodium glycinate to obtain the modified aerogel product.

[0030] The following provides more detailed examples of the preparation of specific strength stabilizers and temporary plugging agents.

[0031] Example 1

[0032] This embodiment prepares a modified aerogel strength stabilizer, including the following process: Weigh each raw material according to the mass ratio, including: 15 parts nanocellulose aerogel, 3 parts dodecyltrimethoxysilane, 1 part γ-glycidoxypropyltrimethoxysilane, and 1.5 parts sodium glycinate.

[0033] Nanocellulose aerogel was impregnated in a 10-fold mixture of ethanol and water (95:5 volume ratio), followed by the addition of dodecyltrimethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane. The pH was adjusted to 4 with acetic acid, and the reaction was carried out at 60°C for 6 hours. After the reaction was completed, the intermediate was lyophilized to obtain the intermediate. The intermediate was then added to a 10-fold mixture of dichloromethane and water (70:30 volume ratio), followed by the addition of sodium glycinate, and then triethylamine was added to adjust the pH to 9. The reaction was stirred at room temperature for 12 hours. After the reaction was completed, the final product was lyophilized and recorded as X-1.

[0034] Example 2

[0035] This embodiment prepares a modified aerogel strength stabilizer, including the following process: Weigh each raw material according to the mass ratio, including: 15 parts nanocellulose aerogel, 4 parts dodecyltrimethoxysilane, 2 parts γ-glycidoxypropyltrimethoxysilane, and 1.5 parts sodium glycinate.

[0036] Nanocellulose aerogel was impregnated in a 10-fold mixture of ethanol and water (95:5 by volume), followed by the addition of dodecyltrimethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane. The pH was adjusted to 4 with acetic acid, and the reaction was carried out at 60°C for 6 hours. After the reaction was completed, the intermediate was lyophilized to obtain an intermediate. The intermediate was then added to a 10-fold mixture of dichloromethane and water (70:30 by volume), followed by the addition of sodium glycinate, and then triethylamine was added to adjust the pH to 9. The reaction was stirred at room temperature for 12 hours. After the reaction was completed, the final product was lyophilized and recorded as X-2.

[0037] Example 3

[0038] This embodiment prepares a modified aerogel strength stabilizer, including the following process: Weigh each raw material according to the mass ratio, including: 15 parts nanocellulose aerogel, 5 parts dodecyltrimethoxysilane, 3 parts γ-glycidyl etheroxypropyltrimethoxysilane, and 1.5 parts sodium glycinate.

[0039] Nanocellulose aerogel was impregnated in a 10-fold mixture of ethanol and water (95:5 by volume), followed by the addition of dodecyltrimethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane. The pH was adjusted to 4 with acetic acid, and the reaction was carried out at 60°C for 6 hours. After the reaction was completed, the intermediate was lyophilized to obtain an intermediate. The intermediate was then added to a 10-fold mixture of dichloromethane and water (70:30 by volume), followed by the addition of sodium glycinate, and then triethylamine was added to adjust the pH to 9. The reaction was stirred at room temperature for 12 hours. After the reaction was completed, the final product was lyophilized and recorded as X-3.

[0040] Example 4

[0041] This embodiment prepares a modified aerogel strength stabilizer, including the following process: Weigh each raw material according to the mass ratio, including: 15 parts nanocellulose aerogel, 3 parts dodecyltrimethoxysilane, 1 part γ-glycidoxypropyltrimethoxysilane, and 3.5 parts sodium glycinate.

[0042] Nanocellulose aerogel was impregnated in a 10-fold mixture of ethanol and water (95:5 by volume), followed by the addition of dodecyltrimethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane. The pH was adjusted to 5 with acetic acid, and the reaction was carried out at 60°C for 6 hours. After the reaction was completed, the intermediate was lyophilized to obtain an intermediate. The intermediate was then added to a 10-fold mixture of dichloromethane and water (70:30 by volume), followed by the addition of sodium glycinate, and then triethylamine was added to adjust the pH to 9. The reaction was stirred at room temperature for 12 hours. After the reaction was completed, the final product was lyophilized and recorded as X-4.

[0043] Example 5

[0044] This embodiment prepares a modified aerogel strength stabilizer, including the following process: Weigh each raw material according to the mass ratio, including: 15 parts nanocellulose aerogel, 5 parts dodecyltrimethoxysilane, 3 parts γ-glycidyl etheroxypropyltrimethoxysilane, and 3.5 parts sodium glycinate.

[0045] Nanocellulose aerogel was impregnated in a 10-fold mixture of ethanol and water (95:5 volume ratio), followed by the addition of dodecyltrimethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane. The pH was adjusted to 4 with acetic acid, and the reaction was carried out at 60°C for 12 hours. After the reaction was completed, the intermediate was lyophilized to obtain the intermediate. The intermediate was then added to a 10-fold mixture of dichloromethane and water (70:30 volume ratio), followed by the addition of sodium glycinate, and then triethylamine was added to adjust the pH to 9. The reaction was stirred at room temperature for 8 hours. After the reaction was completed, the final product was lyophilized and recorded as X-5.

[0046] Comparative Example 1

[0047] This comparative example prepares a modified aerogel strength stabilizer, including the following process: Weigh each raw material according to the mass ratio, including: 15 parts nanocellulose aerogel, 5 parts dodecyltrimethoxysilane, and 3 parts γ-glycidoxypropyltrimethoxysilane.

[0048] Nanocellulose aerogel was impregnated in a 10-fold mixture of ethanol and water (95:5 by volume), then dodecyltrimethoxysilane and γ-glycidyl etheroxypropyltrimethoxysilane were added. The pH was adjusted to 4 with acetic acid, and the reaction was heated to 60°C for 12 hours. After the reaction was completed, the final product was obtained by freeze-drying and recorded as D-1.

[0049] Comparative Example 2

[0050] This embodiment prepares a modified aerogel strength stabilizer, including the following process: Weigh each raw material according to the mass ratio, including: 15 parts nanocellulose aerogel and 3 parts dodecyltrimethoxysilane.

[0051] The nanocellulose aerogel was impregnated in a mixed solvent of 10 times ethanol and water (volume ratio 95:5), then dodecyltrimethoxysilane was added, the pH was adjusted to 4 with acetic acid, and the reaction was heated at 60°C for 6 hours. After the reaction was completed, the final product was obtained by freeze drying and recorded as D-2.

[0052] Comparative Example 3

[0053] This embodiment prepares a modified aerogel strength stabilizer, including the following process: Weigh each raw material according to the mass ratio, including: 15 parts of nanocellulose aerogel and 1 part of γ-glycidoxypropyltrimethoxysilane.

[0054] The nanocellulose aerogel was impregnated in a 10-fold mixture of ethanol and water (volume ratio 95:5), then γ-glycidoxypropyltrimethoxysilane was added, the pH was adjusted to 4 with acetic acid, and the reaction was heated at 60°C for 6 hours. After the reaction was completed, the final product was obtained by freeze-drying and recorded as D-3.

[0055] Comparative Example 4

[0056] This embodiment prepares a modified aerogel strength stabilizer, including the following process: Weigh each raw material according to the mass ratio, including: 15 parts nanocellulose aerogel, 1 part γ-glycidyl etheroxypropyltrimethoxysilane, and 1.5 parts sodium glycinate.

[0057] Nanocellulose aerogel was impregnated in a 10-fold mixture of ethanol and water, then γ-glycidyl etheroxypropyltrimethoxysilane was added, and the pH was adjusted to 4 with acetic acid. The reaction was carried out at 60°C for 6 hours. After the reaction was completed, the intermediate was freeze-dried to obtain an intermediate. The intermediate was added to a 10-fold mixture of dichloromethane and water (volume ratio 70:30), then sodium glycinate was added, followed by triethylamine to adjust the pH to 9. The mixture was stirred at room temperature for 12 hours. After the reaction was completed, the final product was freeze-dried and recorded as D-4.

[0058] Subsequently, the oil absorption ratio of the strength stabilizer prepared above was tested. The specific test process is as follows: Take a certain amount of strength stabilizer, and record its mass as m0. Then soak the strength stabilizer in white oil for 6 hours, and then weigh the mass after absorbing the white oil, and record it as m1. Calculate the oil absorption ratio using the following formula; the higher the oil absorption ratio, the stronger the oil absorption capacity. The test results are shown in Table 1 below.

[0059]

[0060] Table 1 Performance test results of strength stabilizer

[0061] As shown in Table 1, the unmodified nanocellulose aerogel has a low oil absorption ratio of 0.8 times. The strength stabilizer provided in Example 1 has a high oil absorption ratio of 9.2 times, which is sufficient for use as a strength stabilizer. The strength stabilizer provided in Comparative Example D-2 has the highest oil absorption ratio of 11.1 times. However, Comparative Example D-2 only considered oil absorption performance and did not consider the reaction with calcium ions in calcium silicate to stabilize the solidification. Therefore, the product of Example 1 was used as the strength stabilizer in the subsequent formulation.

[0062] Example 6

[0063] This embodiment prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts dicalcium silicate, 5 parts sodium hexametaphosphate, 20 parts basalt fiber, 10 parts strength stabilizer X-1, 0.5 parts polyacrylate and 3 parts water.

[0064] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate and strength stabilizer X-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent E-1.

[0065] Example 7

[0066] This embodiment prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 16 parts tricalcium silicate, 4 parts dicalcium silicate, 5 parts sodium hexametaphosphate, 20 parts basalt fiber, 10 parts strength stabilizer X-1, 0.5 parts polyacrylate and 3 parts water.

[0067] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate and strength stabilizer X-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent E-2.

[0068] Example 8

[0069] This embodiment prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 32 parts tricalcium silicate, 8 parts dicalcium silicate, 5 parts sodium hexametaphosphate, 20 parts basalt fiber, 10 parts strength stabilizer X-1, 0.5 parts polyacrylate and 3 parts water.

[0070] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate and strength stabilizer X-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent E-3.

[0071] Example 9

[0072] This embodiment prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts dicalcium silicate, 10 parts sodium hexametaphosphate, 20 parts basalt fiber, 10 parts strength stabilizer X-1, 1 part polyacrylate and 3 parts water.

[0073] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate and strength stabilizer X-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent E-4.

[0074] Example 10

[0075] This embodiment prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts dicalcium silicate, 15 parts sodium hexametaphosphate, 30 parts basalt fiber, 10 parts strength stabilizer X-1, 1 part polyacrylate and 3 parts water.

[0076] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate and strength stabilizer X-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent E-5.

[0077] Example 11

[0078] This embodiment prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts dicalcium silicate, 10 parts sodium hexametaphosphate, 20 parts basalt fiber, 20 parts strength stabilizer X-1, 1 part polyacrylate and 5 parts water.

[0079] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate and strength stabilizer X-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent E-6.

[0080] Example 12

[0081] This embodiment prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts anhydrous calcium sulfoaluminate, 4 parts monocalcium silicate, 10 parts sodium hexametaphosphate, 20 parts diatomaceous earth, 20 parts strength stabilizer X-1, 1 part polyacrylate and 5 parts water.

[0082] The specific preparation method is as follows: Anhydrous calcium sulfoaluminate and calcium silicate are mixed, and then mixed with sodium hexametaphosphate, diatomaceous earth, polyacrylate and strength stabilizer X-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent E-7.

[0083] Example 13

[0084] This embodiment prepares a temporary plugging agent, including the following process: Weigh each raw material according to the following mass ratio: 6 parts calcium sulfate, 4 parts monocalcium silicate, 10 parts sodium pyrophosphate, 20 parts diatomaceous earth, 20 parts strength stabilizer X-1, 1 part polyetheramine modified styrene-maleic anhydride copolymer, and 5 parts water.

[0085] The specific preparation method is as follows: calcium sulfate and monocalcium silicate are mixed, and then mixed with sodium pyrophosphate, diatomaceous earth, polyetheramine-modified styrene-maleic anhydride copolymer, and strength stabilizer X-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent E-8.

[0086] Example 14

[0087] This embodiment prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts monocalcium silicate, 10 parts citric acid, 20 parts sepiolite, 20 parts strength stabilizer X-1, 1 part polyetheramine modified styrene-maleic anhydride copolymer and 5 parts water.

[0088] The specific preparation method is as follows: Tricalcium silicate and monocalcium silicate are mixed, and then mixed with citric acid, sepiolite, polyetheramine-modified styrene-maleic anhydride copolymer, and strength stabilizer X-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent E-9.

[0089] Example 15

[0090] This embodiment prepares a temporary plugging agent, including the following process: Weigh each raw material according to the following mass ratio: 6 parts tricalcium silicate, 4 parts monocalcium silicate, 10 parts boric acid, 20 parts sepiolite, 20 parts strength stabilizer X-1, 1 part polyetheramine modified styrene-maleic anhydride copolymer, and 5 parts water.

[0091] The specific preparation method is as follows: Tricalcium silicate and monocalcium silicate are mixed, and then mixed with boric acid, sepiolite, polyetheramine-modified styrene-maleic anhydride copolymer, and strength stabilizer X-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent E-10.

[0092] Comparative Example 5

[0093] This comparative example prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts dicalcium silicate, 10 parts sodium hexametaphosphate, 20 parts basalt fiber, 1 part polyacrylate and 5 parts water.

[0094] The specific preparation method is as follows: tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, and polyacrylate. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent G-1.

[0095] Comparative Example 6

[0096] This comparative example prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts dicalcium silicate, 10 parts sodium hexametaphosphate, 20 parts basalt fiber, 20 parts unmodified nanocellulose, 1 part polyacrylate and 5 parts water.

[0097] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate, and unmodified nanocellulose. Finally, water is added to the mixture, and the mixture is stirred evenly to obtain temporary plugging agent G-2.

[0098] Comparative Example 7

[0099] This comparative example prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts dicalcium silicate, 10 parts sodium hexametaphosphate, 20 parts basalt fiber, 20 parts strength stabilizer D-1, 1 part polyacrylate and 5 parts water.

[0100] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate and strength stabilizer D-1. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent G-3.

[0101] Comparative Example 8

[0102] This comparative example prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts dicalcium silicate, 10 parts sodium hexametaphosphate, 20 parts basalt fiber, 20 parts strength stabilizer D-2, 1 part polyacrylate and 5 parts water.

[0103] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate and strength stabilizer D-2. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent G-4.

[0104] Comparative Example 9

[0105] This comparative example prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts dicalcium silicate, 10 parts sodium hexametaphosphate, 20 parts basalt fiber, 20 parts strength stabilizer D-3, 1 part polyacrylate and 5 parts water.

[0106] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate and strength stabilizer D-3. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent G-5.

[0107] Comparative Example 10

[0108] This comparative example prepares a temporary plugging agent, including the following process: Weigh each raw material according to the mass ratio, including: 6 parts tricalcium silicate, 4 parts dicalcium silicate, 10 parts sodium hexametaphosphate, 20 parts basalt fiber, 20 parts strength stabilizer D-4, 1 part polyacrylate and 3 parts water.

[0109] The specific preparation method is as follows: Tricalcium silicate and dicalcium silicate are mixed, and then mixed with sodium hexametaphosphate, basalt fiber, polyacrylate and strength stabilizer D-4. Finally, water is added to the mixture and stirred evenly to obtain temporary plugging agent G-6.

[0110] Based on the above preparation method, temporary plugging agent samples E-1~E-10 and control sample materials G-1~G-6 were prepared by adjusting the types and ratios of raw materials. Subsequently, the key performance of the samples was evaluated according to the corresponding industry standard: SY / T 5840-2024 "Indoor Test Methods for Bridging and Plugging Materials for Drilling Fluids".

[0111] The specific process of the high-temperature and high-pressure dynamic plugging simulation experiment is as follows: Test modules with joint widths of 1-3mm, 3-5mm, and 5-8mm were selected, installed into the test module containers, and sealed. The plugging fluid container lid was opened, the plugging slurry to be tested was added, and the lid was sealed again. The heating temperature was set to 180℃, and the system automatically heated to the required temperature and then maintained a constant temperature. The overburden pressure was simulated using a mechanically assisted pump, and the pressure was maintained constant for at least 5 minutes to conduct a positive plugging experiment. The pressure changes were recorded, and the final pressure displayed was the pressure-bearing plugging capacity. The test results for the maximum pressure-bearing plugging capacity are shown in Table 2.

[0112] Table 2 Performance test results of reservoir protection materials

[0113] As shown in Table 2, the temporary plugging agent provided by this invention exhibits excellent acid solubility, with an acid solubility rate exceeding 90.0%, thus achieving the purpose of reservoir protection. Simultaneously, this material demonstrates excellent pressure-bearing plugging capability, with the maximum pressure-bearing plugging capability of simulated leaky layers with different fracture widths exceeding 20 MPa. Figure 3 The test diagram shows the pressure-bearing sealing capacity test of the temporary plugging agent E6 in simulated cracks (5-8mm crack width).

[0114] Temporary plugging agents E6, G1, and G2 were mixed with oil-based drilling fluid in different proportions. The compressive strength of this mixture was evaluated according to the standard method of GB / T 19139-2012 "Test Methods for Oil Well Cement". The results are shown in Table 3. The compressive strength test results for temporary plugging agent E6 are as follows: Figure 4 As shown.

[0115] Table 3. Test results of compressive strength of temporary plugging agents E6, G1, and G2 mixed with oil-based drilling fluid.

[0116] Table 3 shows that when the temporary plugging agent E6 provided by this invention is not mixed with oil-based drilling fluid, the solidified body has a strong compressive strength, reaching 19.6 MPa. When the mixing ratio of temporary plugging agent E6 with oil-based drilling fluid is less than 7:3, the temporary plugging agent always maintains effective solidification ability, showing strong anti-fouling properties against oil-based drilling fluid. Temporary plugging agents G1 and G2 cannot maintain effective solidification when the mixing ratio with oil-based drilling fluid is less than 9:1.

[0117] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A strength stabilizer, wherein, The strength stabilizer is a modified aerogel, and the structural formula of the modified aerogel is as follows: In the formula, A represents aerogel.

2. The strength stabilizer according to claim 1, wherein, The aerogel is a nanocellulose aerogel.

3. A method for preparing the strength stabilizer according to claim 1 or 2, wherein, The preparation method includes the following steps: The aerogel was added to the first solvent, followed by dodecyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane. The pH was adjusted to 4, and the mixture was heated to carry out the first reaction. After the reaction was completed, the intermediate was obtained by freeze drying. The intermediate was added to the second solvent, sodium glycinate was added, the pH was adjusted to 9, and the mixture was stirred at room temperature to carry out the second reaction. After the reaction was completed, the modified aerogel was obtained by freeze drying.

4. The preparation method according to claim 3, wherein, The mass ratio of the aerogel, dodecyltrimethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane and sodium glycinate is 15:(3-5):(1-3):(1.5-3.5).

5. The preparation method according to claim 3, wherein, The first solvent is a mixture of ethanol and water, and the second solvent is a mixture of dichloromethane and water.

6. The preparation method according to claim 3, wherein, The pH was adjusted to 4 using acetic acid and to 9 using triethylamine.

7. The preparation method according to claim 3, wherein, The temperature of the first reaction is 50-70℃, and the time is 6-12 hours; The second reaction was carried out at room temperature for 8-12 hours.

8. A temporary plugging agent, wherein, The temporary plugging agent comprises, by weight, the following: 10-40 parts curing agent, 5-10 parts retarder, 20-30 parts filter aid, 10-20 parts strength stabilizer as described in claim 1 or 2, 0.5-1 part dispersant and 3-5 parts water; The curing agent is selected from at least one of tricalcium silicate, dicalcium silicate, monocalcium silicate, anhydrous calcium sulfoaluminate, and calcium sulfate. The retarder is selected from at least one of sodium pyrophosphate, citric acid, boric acid, and sodium hexametaphosphate; The filter aid is selected from at least one of diatomaceous earth, basalt fiber, and sepiolite; The dispersant is selected from polyacrylate and polyetheramine modified styrene-maleic anhydride copolymer.

9. A method for preparing the temporary plugging agent according to claim 8, wherein, The preparation method includes the following steps: The curing agent, retarder, filter aid, strength stabilizer and dispersant are mixed evenly to obtain a solid mixture; then water is added and stirred evenly to obtain the temporary plugging agent.

10. The application of the temporary plugging agent of claim 8 in deep or ultra-deep oil and gas reservoirs.

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