Multi-stage activation responsive differential pressure sealants and their preparation and use

Abstract

This invention discloses a multi-stage activated response differential pressure sealant, comprising a base sealing material, microcapsules, and expanded graphite; wherein the microcapsules are microcapsules containing a sealing active substance, and the sealing active substance is an epoxy-amino resin. The multi-stage activated response differential pressure sealant provided by this invention achieves multi-stage activation under low, medium, and high pressure environments. During pressure differential changes, the multi-stage activated response differential pressure sealant provided by this invention can progressively activate different components, thereby providing a continuous and reliable sealing effect. The multi-stage response mechanism of the multi-stage activated response differential pressure sealant provided by this invention effectively extends the service life of the sealant and significantly improves the overall safety of the sealing system, reducing the risk of failure caused by excessively large or small pressure differentials.

Description

Technical Field

[0001] This invention relates to a multi-stage activated differential pressure sealant, its preparation, and its application. Background Technology

[0002] In oil and gas well sealing technology, traditional sealing methods typically focus on addressing a single differential pressure activation problem. Existing technologies mostly rely on integral sealing materials and a single differential pressure activation mechanism. While these technologies meet the sealing requirements of oil and gas wells to some extent, they often exhibit limitations when facing complex wellbore environments.

[0003] Existing patent technology: CN104151652B: This patent introduces a pressure differential activated sealant and its preparation method. Although it can be activated under a specific pressure differential to form a seal, its technical solution mainly targets a single pressure differential condition and does not address how to handle the multi-level pressure segmented sealing requirements inside the wellbore. In practical applications, this single pressure differential activated sealant may not be effective in dealing with the challenges posed by pressure differences at different levels within the wellbore.

[0004] CN110218554A discloses a differential pressure activation sealing agent for oil and gas wells, aiming to solve sealing problems in high-pressure environments. However, the design of this sealing agent still focuses on handling single differential pressure activation, and fails to effectively address the complex pressure distribution and segmented sealing requirements within the wellbore. The limitation of this technology lies in its inability to cope with the sealing challenges posed by multi-stage pressure changes within the wellbore.

[0005] Existing research has explored the application of flexible sealing materials in oil and gas wells, focusing on the overall performance of the materials, including their performance under high pressure and high temperature environments. While these materials improve sealing effectiveness to some extent, they typically lack specific research on pressure-stage sealing. Therefore, they may not be effective in handling multi-stage pressure problems within the wellbore.

[0006] Existing technologies have also investigated high-performance polymer sealing systems under extreme conditions. While these systems have some adaptability to high-temperature and high-pressure conditions, the technical challenges in dealing with pressure gradations and multi-stage differential pressure activation remain unresolved. Most existing sealing systems rely on holistic solutions and lack detailed mechanisms for handling different pressure ranges.

[0007] Currently, most technologies focus on single differential pressure activation or overall sealing solutions. While these technologies perform well under specific conditions, they exhibit limitations when facing the complex pressure environment inside the wellbore, especially in scenarios requiring segmented handling of different pressure conditions. This limitation primarily manifests in the inability to effectively address the sealing needs of multi-stage pressure variations within the wellbore, leading to insufficient sealing or poor repair results.

[0008] In summary, existing technologies have significant shortcomings in pressure-stage sealing, especially when dealing with complex pressure distributions and multi-stage differential pressure activation within the wellbore, posing considerable challenges. Therefore, innovative solutions to these problems have significant practical implications and promising application prospects. Summary of the Invention

[0009] The purpose of this invention is to provide a novel pressure-segmented sealing technology to overcome the shortcomings of existing technologies in the complex pressure environment of oil and gas wells. Specifically, this invention aims to achieve multi-stage pressure-segmented sealing, developing a technology capable of effective sealing at different pressure stages within the wellbore, thereby solving the problem that existing sealants cannot cope with multi-stage pressure changes.

[0010] As one aspect of the present invention, a multi-stage activated response differential pressure sealant is disclosed, comprising a base sealing material, microcapsules, and expanded graphite; wherein the microcapsules are microcapsules containing a sealing active substance, and the sealing active substance is an epoxy amino resin.

[0011] In a specific implementation, the basic sealing material is hydrogenated nitrile rubber latex.

[0012] As another aspect of the present invention, a method for preparing the above-described multi-stage activated response differential pressure sealant is provided, the method comprising:

[0013] (1) Dissolve 10-20 parts by weight of toluene diisocyanate and 30-50 parts by weight of polyether polyol in 100 parts by weight of cyclohexanone to obtain a precursor solution;

[0014] (2) Add 2 to 5 parts by weight of polyvinyl alcohol to 500 parts by weight of water to obtain a polyvinyl alcohol aqueous solution;

[0015] (3) Mix 10-20 parts by weight of epoxy amino resin and 1-2 parts by weight of epoxy diluent to obtain the encapsulated liquid phase;

[0016] (4) Add the precursor solution obtained in step (1) to the polyvinyl alcohol aqueous solution obtained in step (2), and under stirring conditions at 60-80°C, add the encapsulating liquid phase obtained in step (3) to obtain microcapsules containing sealing active substances.

[0017] (5) Add 1-3 parts by weight of the microcapsules containing the sealing active substance and 1-3 parts of expanded graphite to 100 parts of the base sealing material, and mix.

[0018] (6) Add 5-10 parts by weight of activator and stir; add 1-2 parts by weight of terminator and stir; add 1-3 parts by weight of stabilizer and stir.

[0019] In a specific implementation, the basic sealing material is hydrogenated nitrile rubber latex.

[0020] In a specific implementation, the epoxy diluent is an epoxy fatty acid ester.

[0021] In a specific implementation, the terminator is Span 80, and the stabilizer is potassium polyacrylate.

[0022] In a specific implementation, step (6) involves adding the activator at a rate of ≤70 drops / minute.

[0023] In a specific implementation, step (6) involves adding the activator at a rate of ≤40 drops / minute.

[0024] In a specific implementation, the activator is a magnesium chloride solution with a concentration of 0.1–0.3 g / L.

[0025] As another aspect of the present invention, the application of the above-mentioned multi-stage activation response differential pressure sealant in oil and gas well plugging is involved.

[0026] The multi-stage activation response differential pressure sealant provided by this invention achieves multi-stage activation under low, medium, and high pressure environments. During pressure differential changes, the multi-stage activation response differential pressure sealant can progressively activate different components, thereby providing a continuous and reliable sealing effect. The multi-stage response mechanism of the multi-stage activation response differential pressure sealant provided by this invention effectively extends the service life of the sealant and significantly improves the overall safety of the sealing system, reducing the risk of failure caused by excessively large or small pressure differentials. Detailed Implementation

[0027] In this embodiment of the invention, the hydrogenated nitrile butadiene latex is from Baoqian Plastics Technology Co., Ltd.

[0028] The epoxy fatty acid ester was sourced from Guangzhou Fufeng Chemical Co., Ltd.

[0029] The epoxy amino resin is epoxy amino resin AFG-90H, which comes from Wuhan Kemic Biomedical Technology Co., Ltd.

[0030] Example 1

[0031] Preparation of sealant:

[0032] Add 10 parts by weight of activator to 100 parts by weight of hydrogenated nitrile rubber latex at a rate of 70 drops / min and stir for 20 minutes; add 2 parts by weight of terminator and 3 parts by weight of stabilizer and stir for 8 minutes to obtain sealant.

[0033] The activator is a magnesium chloride aqueous solution with a concentration of 0.3 g / L;

[0034] The terminator is Span 80 (SP-80);

[0035] The stabilizer is potassium polyacrylate (K-pam).

[0036] Performance testing:

[0037] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the sealant prepared in this embodiment to the sealing test device, apply appropriate pressure to the pressure port, and test its sealing effect. The results are shown in Table 1.

[0038] Table 1 Pressure Testing and Blocking Status

[0039] Pressure (MPa) 0.5 0.8 1 10 15 18 Duration (min) 30 30 30 30 30 30 Blocking situation Unsealed Unsealed Block Block Block Unsealed

[0040] As shown in Table 1, the sealant prepared in this embodiment cannot be activated by a pressure difference below 0.8 MPa, has a sealing effect on cracks under pressure of 1-15 MPa, and cannot seal cracks when the pressure is greater than 15 MPa.

[0041] Example 2

[0042] Preparation of sealant:

[0043] Add 10 parts by weight of activator to 100 parts by weight of hydrogenated nitrile rubber latex at a rate of 100 drops / min and stir for 20 minutes; add 2 parts by weight of terminator and 3 parts by weight of stabilizer and stir for 8 minutes to obtain sealant.

[0044] The activator is a magnesium chloride aqueous solution with a concentration of 0.3 g / L;

[0045] The terminator is Span 80 (SP-80);

[0046] The stabilizer is potassium polyacrylate (K-pam).

[0047] Performance testing:

[0048] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the sealant prepared in this embodiment to the sealing test device, apply appropriate pressure to the pressure port, and test its sealing effect. The results are shown in Table 2.

[0049] Table 2 Pressure Testing and Blocking Status

[0050] Pressure (MPa) 0.5 0.8 1 10 15 18 Duration (min) 30 30 30 30 30 30 Blocking situation Unsealed Unsealed Unsealed Block Block Unsealed

[0051] As shown in Table 2, the sealant prepared in this embodiment cannot be activated by a pressure difference below 1 MPa, has a sealing effect on cracks under a pressure of 10-15 MPa, and cannot seal cracks when the pressure is greater than 15 MPa.

[0052] Example 3

[0053] Preparation of sealant:

[0054] Add 10 parts by weight of activator to 100 parts by weight of hydrogenated nitrile rubber latex at a rate of 50 drops / min and stir for 20 minutes; add 2 parts by weight of terminator and 3 parts by weight of stabilizer and stir for 8 minutes to obtain sealant.

[0055] The activator is a magnesium chloride aqueous solution with a concentration of 0.3 g / L;

[0056] The terminator is Span 80 (SP-80);

[0057] The stabilizer is potassium polyacrylate (K-pam).

[0058] Performance testing:

[0059] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the sealant prepared in this embodiment to the sealing test device, apply appropriate pressure to the pressure port, and test its sealing effect. The results are shown in Table 3.

[0060] Table 3 Pressure Testing and Blocking Status

[0061] Pressure (MPa) 0.5 0.8 1 10 15 18 Duration (min) 30 30 30 30 30 30 Blocking situation Unsealed Block Block Block Block Unsealed

[0062] As shown in Table 3, the sealant prepared in this embodiment cannot be activated by a pressure difference below 0.5 MPa, but can be activated at 0.8 MPa. It has a sealing effect on cracks at pressures of 0.8-15 MPa, but cannot seal cracks at pressures greater than 15 MPa.

[0063] Example 4

[0064] Preparation of sealant:

[0065] Add 10 parts by weight of activator to 100 parts by weight of hydrogenated nitrile rubber latex at a rate of 30 drops / min and stir for 20 minutes; add 2 parts by weight of terminator and 3 parts by weight of stabilizer and stir for 8 minutes to obtain sealant.

[0066] The activator is a magnesium chloride aqueous solution with a concentration of 0.3 g / L;

[0067] The terminator Span 80 (SP-80);

[0068] The stabilizer is potassium polyacrylate (K-pam).

[0069] Performance testing:

[0070] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the sealant prepared in this embodiment to the sealing test device, apply appropriate pressure through the pressure port, and test its sealing effect. The results are shown in Table 4.

[0071] Table 4 Pressure Testing and Blocking Status

[0072] Pressure (MPa) 0.5 0.8 1 10 15 18 Duration (min) 30 30 30 30 30 30 Blocking situation Block Block Block Block Block Unsealed

[0073] As shown in Table 4, the sealant prepared in this embodiment can be activated at 0.5 MPa and has a sealing effect on cracks under pressure of 0.5-15 MPa, but cannot seal cracks under pressure greater than 15 MPa.

[0074] Example 5

[0075] Preparation of multi-stage activated response differential pressure sealant:

[0076] (1) Dissolve 10 parts by mass of toluene diisocyanate (TDI) and 30 parts by mass of polyether polyol in 100 parts by mass of cyclohexanone to obtain a precursor solution;

[0077] (2) Add 2 parts by mass of polyvinyl alcohol (PVA) to 500 parts by mass of water to obtain a polyvinyl alcohol aqueous solution;

[0078] (3) Mix 10 parts by weight of epoxy amino resin and 1 part by weight of epoxy diluent to obtain the encapsulated liquid phase;

[0079] (4) Add the precursor solution obtained in step (1) to the polyvinyl alcohol aqueous solution obtained in step (2), and add the encapsulating liquid phase obtained in step (3) under stirring conditions at 60°C to obtain microcapsules containing sealing active substances.

[0080] (5) Wash the microcapsules containing the sealing active substance obtained in step (4) with water and dry them to obtain the final microcapsule product.

[0081] (6) Add 1 part by mass of the above microcapsule product to 100 parts by mass of hydrogenated nitrile latex and mix; add 5 parts by mass of activator at a rate of 40 drops / min and stir for 20 minutes; add 1 part by mass of terminator and stir for 20 minutes; add 1 part by mass of stabilizer and stir for 8 minutes to obtain multi-stage activation response differential pressure sealant.

[0082] The epoxy diluent is an epoxy fatty acid ester;

[0083] The activator is a magnesium chloride aqueous solution with a concentration of 0.1 g / L;

[0084] The terminator is Span 80 (SP-80);

[0085] The stabilizer is potassium polyacrylate (K-pam);

[0086] The polyether polyol is polypropylene glycol PPG-8000, which comes from Jiangsu Maoheng Chemical Co., Ltd.

[0087] The polyvinyl alcohol is PVA1799, sourced from Shenzhen Yoshida Chemical Co., Ltd.

[0088] Performance testing:

[0089] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the multi-stage activated response differential pressure sealant prepared in this embodiment to the sealing test device, apply appropriate pressure through the pressure port, and test its sealing effect. The results are shown in Table 5.

[0090] Table 5 Pressure Testing and Sealing Status

[0091] Pressure (MPa) 0.8 1 10 15 20 25 30 32 Duration (min) 30 30 30 30 30 30 30 30 Blocking situation Unsealed Block Block Block Block Block Block Unsealed

[0092] As shown in Table 5, the multi-stage activation response differential pressure sealant prepared in this embodiment cannot be activated by a differential pressure below 0.8 MPa, but can be activated at 1 MPa. It has a sealing effect on cracks under pressures of 1-30 MPa, but cannot seal cracks under pressures greater than 30 MPa.

[0093] Example 6

[0094] Preparation of multi-stage activation response differential pressure sealant:

[0095] (1) Dissolve 20 parts by mass of toluene diisocyanate (TDI) and 50 parts by mass of polyether polyol in 100 parts by mass of cyclohexanone to obtain a precursor solution;

[0096] (2) Add 5 parts by mass of polyvinyl alcohol (PVA) to 500 parts by mass of water to obtain a polyvinyl alcohol aqueous solution;

[0097] (3) Mix 20 parts by weight of epoxy amino resin and 2 parts by weight of epoxy diluent to obtain the encapsulated liquid phase;

[0098] (4) Add the precursor solution obtained in step (1) to the polyvinyl alcohol aqueous solution obtained in step (2), and add the encapsulating liquid phase obtained in step (3) under stirring conditions at 80°C to obtain microcapsules containing sealing active substances.

[0099] (5) Wash the microcapsules containing the sealing active substance obtained in step (4) with water and dry them to obtain the final microcapsule product.

[0100] (6) Add 3 parts by mass of the above microcapsule product to 100 parts by mass of hydrogenated nitrile latex and mix; add 10 parts by mass of activator at a rate of 70 drops / min and stir for 20 minutes; add 2 parts by mass of terminator and stir for 20 minutes; add 3 parts by mass of stabilizer and stir for 8 minutes to obtain multi-stage activation response differential pressure sealant.

[0101] The epoxy diluent is an epoxy fatty acid ester;

[0102] The activator is a magnesium chloride aqueous solution with a concentration of 0.3 g / L;

[0103] The terminator is Span 80 (SP-80);

[0104] The stabilizer is potassium polyacrylate (K-pam);

[0105] The polyether polyol is polypropylene glycol PPG-8000, which comes from Jiangsu Maoheng Chemical Co., Ltd.

[0106] The polyvinyl alcohol is PVA1799, sourced from Shenzhen Yoshida Chemical Co., Ltd.

[0107] Performance testing:

[0108] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the multi-stage activated response differential pressure sealant prepared in this embodiment to the sealing test device, apply appropriate pressure through the pressure port, and test its sealing effect. The results are shown in Table 6.

[0109] Table 6 Pressure Testing and Blocking Status

[0110] Pressure (MPa) 0.5 0.8 1 10 15 20 25 30 32 Duration (min) 30 30 30 30 30 30 30 30 30 Blocking situation Block Block Block Block Block Block Block Block Unsealed

[0111] As shown in Table 6, the multi-stage activation response differential pressure sealant prepared in this embodiment can be activated at 0.5 MPa and has a sealing effect on cracks at pressures of 0.5-30 MPa, but cannot seal cracks at pressures greater than 30 MPa.

[0112] Example 7

[0113] Preparation of multi-stage activated response differential pressure sealant:

[0114] Add 1 part by mass of expanded graphite to 100 parts by mass of hydrogenated nitrile rubber latex and mix; add 5 parts by mass of activator at a rate of 40 drops / min and stir for 20 minutes; add 1 part by mass of terminator and stir for 20 minutes; add 1 part by mass of stabilizer and stir for 8 minutes to obtain a multi-stage activated response differential pressure sealant.

[0115] The activator is a magnesium chloride aqueous solution with a concentration of 0.1 g / L;

[0116] The terminator is Span 80 (SP-80);

[0117] The stabilizer is potassium polyacrylate (K-pam).

[0118] Performance testing:

[0119] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the multi-stage activated response differential pressure sealant prepared in this embodiment to the sealing test device, apply appropriate pressure through the pressure port, and test its sealing effect. The results are shown in Table 7.

[0120] Table 7 Pressure Testing and Sealing Status

[0121] Pressure (MPa) 0.8 1 10 15 20 32 40 80 Duration (min) 30 30 30 30 30 30 30 30 Blocking situation Unsealed Block Block Unsealed Unsealed Block Block Block

[0122] As shown in Table 7, the multi-stage activation response differential pressure sealant prepared in this embodiment cannot be activated by a differential pressure below 0.8 MPa, but can be activated at 1 MPa. It has a sealing effect on cracks at pressures of 1 MPa-10 MPa, and still has a sealing effect at pressures of 32 MPa-80 MPa, but cannot seal cracks at 15-20 MPa.

[0123] Example 8

[0124] Preparation of multi-stage activation response differential pressure sealant:

[0125] Add 3 parts by mass of expanded graphite to 100 parts by mass of hydrogenated nitrile rubber latex and mix; add 10 parts by mass of activator at a rate of 70 drops / min and stir for 20 minutes; add 2 parts by mass of terminator and stir for 20 minutes; add 3 parts by mass of stabilizer and stir for 8 minutes to obtain a multi-stage activated response differential pressure sealant.

[0126] in,

[0127] The activator is a magnesium chloride aqueous solution with a concentration of 0.3 g / L;

[0128] The terminator is Span 80 (SP-80);

[0129] The stabilizer is potassium polyacrylate (K-pam);

[0130] Performance testing:

[0131] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the multi-stage activated response differential pressure sealant prepared in this embodiment to the sealing test device, apply appropriate pressure through the pressure port, and test its sealing effect. The results are shown in Table 8.

[0132] Table 8 Pressure Testing and Sealing Status

[0133] Pressure (MPa) 0.5 0.8 1 10 15 20 32 40 80 Duration (min) 30 30 30 30 30 30 30 30 30 Blocking situation Block Unsealed Block Block Unsealed Unsealed Block Block Block

[0134] As shown in Table 8, the multi-stage activation response differential pressure sealant prepared in this embodiment can be activated at 0.5 MPa, and has a sealing effect on cracks at pressures of 1 MPa-10 MPa. It also has a sealing effect on cracks at pressures of 32 MPa-80 MPa, but it cannot seal cracks at 0.8 MPa and 15-20 MPa.

[0135] Example 9

[0136] Preparation of multi-stage activated response differential pressure sealant:

[0137] (1) Dissolve 10 parts by mass of toluene diisocyanate (TDI) and 30 parts by mass of polyether polyol in 100 parts by mass of cyclohexanone to obtain a precursor solution;

[0138] (2) Add 2 parts by mass of polyvinyl alcohol (PVA) to 500 parts by mass of water to obtain a polyvinyl alcohol aqueous solution;

[0139] (3) Mix 10 parts by weight of epoxy amino resin and 1 part by weight of epoxy diluent to obtain the encapsulated liquid phase;

[0140] (4) Add the precursor solution obtained in step (1) to the polyvinyl alcohol aqueous solution obtained in step (2), and add the encapsulating liquid phase obtained in step (3) under stirring conditions at 60°C to obtain microcapsules containing sealing active substances.

[0141] (5) Wash the microcapsules containing the sealing active substance obtained in step (4) with water and dry them to obtain the final microcapsule product.

[0142] (6) Add 1 part by mass of the above microcapsule product and 1 part by mass of expanded graphite to 100 parts by mass of hydrogenated nitrile latex; add 5 parts by mass of activator at a rate of 70 drops / min and stir for 20 minutes; add 1 part by mass of terminator and stir for 20 minutes; add 1 part by mass of stabilizer and stir for 8 minutes to obtain multi-stage activated response differential pressure sealant.

[0143] The epoxy diluent is an epoxy fatty acid ester;

[0144] The activator is a magnesium chloride aqueous solution with a concentration of 0.1 g / L;

[0145] The terminator is Span 80 (SP-80);

[0146] The stabilizer is potassium polyacrylate (K-pam);

[0147] The polyether polyol is polypropylene glycol PPG-8000, which comes from Jiangsu Maoheng Chemical Co., Ltd.

[0148] The polyvinyl alcohol, PVA1799, is from Shenzhen Yoshida Chemical Co., Ltd.

[0149] Performance testing:

[0150] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the multi-stage activated response differential pressure sealant prepared in this embodiment to the sealing test device, apply appropriate pressure through the pressure port, and test its sealing effect. The results are shown in Table 9.

[0151] Table 9 Pressure Testing and Blocking Status

[0152] Pressure (MPa) 0.8 1 10 15 20 32 40 80 Duration (min) 30 30 30 30 30 30 30 30 Blocking situation Unsealed Block Block Block Block Block Block Block

[0153] As shown in Table 9, the multi-stage activation response differential pressure sealant prepared in this embodiment cannot be activated by a differential pressure of 0.8 MPa, but can be activated at 1 MPa, and has a sealing effect on cracks under pressures of 1 MPa-80 MPa.

[0154] Example 10

[0155] Preparation of multi-stage activation response differential pressure sealant:

[0156] (1) Dissolve 20 parts by mass of toluene diisocyanate (TDI) and 50 parts by mass of polyether polyol in 100 parts by mass of cyclohexanone to obtain a precursor solution;

[0157] (2) Add 5 parts by mass of polyvinyl alcohol (PVA) to 500 parts by mass of water to obtain a polyvinyl alcohol aqueous solution;

[0158] (3) Mix 20 parts by weight of epoxy amino resin and 2 parts by weight of epoxy diluent to obtain the encapsulated liquid phase;

[0159] (4) Add the precursor solution obtained in step (1) to the polyvinyl alcohol aqueous solution obtained in step (2), and add the encapsulating liquid phase obtained in step (3) under stirring conditions at 80°C to obtain microcapsules containing sealing active substances.

[0160] (5) Wash the microcapsules containing the sealing active substance obtained in step (4) with water and dry them to obtain the final microcapsule product.

[0161] (6) Add 3 parts by mass of the above microcapsule product and 3 parts by mass of expanded graphite to 100 parts by mass of hydrogenated nitrile latex; add 10 parts by mass of activator at a rate of 60 drops / min and stir for 20 minutes; add 2 parts by mass of terminator and stir for 20 minutes; add 3 parts by mass of stabilizer and stir for 8 minutes to obtain multi-stage activated response differential pressure sealant.

[0162] The epoxy diluent is an epoxy fatty acid ester;

[0163] The activator is a magnesium chloride aqueous solution with a concentration of 0.3 g / L;

[0164] The terminator is Span 80 (SP-80);

[0165] The stabilizer is potassium polyacrylate (K-pam);

[0166] The polyether polyol is polypropylene glycol PPG-8000, which comes from Jiangsu Maoheng Chemical Co., Ltd.

[0167] The polyvinyl alcohol is PVA1799, sourced from Shenzhen Yoshida Chemical Co., Ltd.

[0168] Performance testing:

[0169] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the multi-stage activated response differential pressure sealant prepared in this embodiment to the sealing test device, apply appropriate pressure through the pressure port, and test its sealing effect. The results are shown in Table 10.

[0170] Table 10 Pressure Testing and Blocking Status

[0171] Pressure (MPa) 0.8 1 10 15 20 32 40 80 Duration (min) 30 30 30 30 30 30 30 30 Blocking situation Unsealed Block Block Block Block Block Block Block

[0172] As shown in Table 10, the multi-stage activation response differential pressure sealant prepared in this embodiment cannot be activated by a differential pressure of 0.8 MPa, but can be activated at 1 MPa, and has a sealing effect on cracks under pressures of 1 MPa-80 MPa.

[0173] Example 11

[0174] Preparation of multi-stage activation response differential pressure sealant:

[0175] (1) Dissolve 10 parts by mass of toluene diisocyanate (TDI) and 30 parts by mass of polyether polyol in 100 parts by mass of cyclohexanone to obtain a precursor solution;

[0176] (2) Add 2 parts by mass of polyvinyl alcohol (PVA) to 500 parts by mass of water to obtain a polyvinyl alcohol aqueous solution;

[0177] (3) Mix 10 parts by weight of epoxy amino resin and 1 part by weight of epoxy diluent to obtain the encapsulated liquid phase;

[0178] (4) Add the precursor solution obtained in step (1) to the polyvinyl alcohol aqueous solution obtained in step (2), and add the encapsulating liquid phase obtained in step (3) under stirring conditions at 60°C to obtain microcapsules containing sealing active substances.

[0179] (5) Wash the microcapsules containing the sealing active substance obtained in step (4) with water and dry them to obtain the final microcapsule product.

[0180] (6) Add 1 part by mass of the above microcapsule product and 1 part by mass of expanded graphite to 100 parts by mass of hydrogenated nitrile latex; add 5 parts by mass of activator at a rate of 50 drops / min and stir for 20 minutes; add 1 part by mass of terminator and stir for 20 minutes; add 1 part by mass of stabilizer and stir for 8 minutes to obtain multi-stage activation response differential sealant.

[0181] The epoxy diluent is an epoxy fatty acid ester;

[0182] The activator is a magnesium chloride aqueous solution with a concentration of 0.1 g / L;

[0183] The terminator is Span 80 (SP-80);

[0184] The stabilizer is potassium polyacrylate (K-pam);

[0185] The polyether polyol is polypropylene glycol PPG-8000, which comes from Jiangsu Maoheng Chemical Co., Ltd.

[0186] The polyvinyl alcohol is PVA1799, sourced from Shenzhen Yoshida Chemical Co., Ltd.

[0187] Performance testing:

[0188] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the multi-stage activated response differential pressure sealant prepared in this embodiment to the sealing test device, apply appropriate pressure through the pressure port, and test its sealing effect. The results are shown in Table 11.

[0189] Table 11 Pressure Testing and Blocking Status

[0190] Pressure (MPa) 0.8 1 10 15 20 32 40 80 Duration (min) 30 30 30 30 30 30 30 30 Blocking situation Unsealed Block Block Block Block Block Block Block

[0191] As shown in Table 11, the multi-stage activation response differential pressure sealant prepared in this embodiment cannot be activated by a differential pressure below 0.8 MPa, but can be activated at 1 MPa, and has a sealing effect on cracks under pressures of 1 MPa-80 MPa.

[0192] Example 12

[0193] Preparation of multi-stage activation response differential pressure sealant:

[0194] (1) Dissolve 20 parts by mass of toluene diisocyanate (TDI) and 50 parts by mass of polyether polyol in 100 parts by mass of cyclohexanone to obtain a precursor solution;

[0195] (2) Add 5 parts by mass of polyvinyl alcohol (PVA) to 500 parts by mass of water to obtain a polyvinyl alcohol aqueous solution;

[0196] (3) Mix 20 parts by weight of epoxy amino resin and 2 parts by weight of epoxy diluent to obtain the encapsulated liquid phase;

[0197] (4) Add the precursor solution obtained in step (1) to the polyvinyl alcohol aqueous solution obtained in step (2), and add the encapsulating liquid phase obtained in step (3) under stirring conditions at 80°C to obtain microcapsules containing sealing active substances.

[0198] (5) Wash the microcapsules containing the sealing active substance obtained in step (4) with water and dry them to obtain the final microcapsule product.

[0199] (6) Add 3 parts by mass of the above microcapsule product and 3 parts by mass of expanded graphite to 100 parts by mass of hydrogenated nitrile latex; add 10 parts by mass of activator at a rate of 40 drops / min and stir for 20 minutes; add 2 parts by mass of terminator and stir for 20 minutes; add 3 parts by mass of stabilizer and stir for 8 minutes to obtain multi-stage activated response differential pressure sealant.

[0200] The epoxy diluent is an epoxy fatty acid ester;

[0201] The activator is a magnesium chloride aqueous solution with a concentration of 0.3 g / L;

[0202] The terminator is Span 80 (SP-80);

[0203] The stabilizer is potassium polyacrylate (K-pam);

[0204] The polyether polyol is polypropylene glycol PPG-8000, which comes from Jiangsu Maoheng Chemical Co., Ltd.

[0205] The polyvinyl alcohol is PVA1799, sourced from Shenzhen Yoshida Chemical Co., Ltd.

[0206] Performance testing:

[0207] After tightening the inner thread of the sealing test device, rotate it 360° in the opposite direction so that one thread is not tightened. Add 5 kg of the multi-stage activated response differential pressure sealant prepared in this embodiment to the sealing test device, apply appropriate pressure through the pressure port, and test its sealing effect. The results are shown in Table 12.

[0208] Table 12 Pressure Testing and Blocking Status

[0209] Pressure (MPa) 0.5 0.8 1 10 15 20 32 40 80 Duration (min) 30 30 30 30 30 30 30 30 30 Blocking situation Block Block Block Block Block Block Block Block Block

[0210] As shown in Table 12, the multi-stage activation response differential pressure sealant prepared in this embodiment can be activated at 0.5 MPa and has a sealing effect on cracks under pressures of 0.5 MPa to 30 MPa.

[0211] As can be seen from the above embodiments, compared with Embodiments 1-8, the multi-stage activated response differential pressure sealant prepared in Embodiments 9-12 has a sealing effect under pressures of 1MPa-80MPa. The multi-stage activated response differential pressure sealant prepared in Embodiments 9-12 can effectively meet the sealing requirements under different differential pressure environments. Among Embodiments 9-12, Embodiment 12 has a sealing effect under pressures of 0.8-80MPa, with a wider sealing pressure range.

[0212] The multi-stage activation response differential pressure sealant of Examples 9-12 can be summarized as follows:

[0213] A multi-stage activated response differential pressure sealant comprising a base sealing material, microcapsules, and expanded graphite; wherein the microcapsules are microcapsules containing a sealing active substance, and the sealing active substance is an epoxy amino resin; the base sealing material is hydrogenated nitrile butadiene latex.

[0214] The methods for preparing multi-stage activated differential pressure sealants in Examples 9-12 can be summarized as follows:

[0215] (1) Dissolve 10-20 parts by weight of toluene diisocyanate and 30-50 parts by weight of polyether polyol in 100 parts by weight of cyclohexanone to obtain a precursor solution;

[0216] (2) Add 2 to 5 parts by weight of polyvinyl alcohol to 500 parts by weight of water to obtain a polyvinyl alcohol aqueous solution;

[0217] (3) Mix 10-20 parts by weight of epoxy amino resin and 1-2 parts by weight of epoxy diluent to obtain the encapsulated liquid phase;

[0218] (4) Add the precursor solution obtained in step (1) to the polyvinyl alcohol aqueous solution obtained in step (2), and add the encapsulating liquid phase obtained in step (3) under stirring conditions at 60-80℃ to obtain microcapsules containing sealing active substances.

[0219] (5) Add 1-3 parts by weight of the microcapsules containing the sealing active substance and 1-3 parts of expanded graphite to 100 parts of the base sealing material and mix.

[0220] (6) Add 5-10 parts by weight of activator and stir; add 1-2 parts by weight of terminator and stir; add 1-3 parts by weight of stabilizer and stir.

[0221] The basic sealing material is hydrogenated nitrile rubber latex; the epoxy diluent is an epoxy fatty acid ester.

[0222] The terminator is Span 80, and the stabilizer is potassium polyacrylate;

[0223] The activator is a magnesium chloride solution with a concentration of 0.1–0.3 g / L.

[0224] In step (6), the activator is added at a rate of ≤70 drops / minute; preferably, the activator is added at a rate of ≤40 drops / minute.

Claims

1. A multi-stage activation responsive differential pressure seal characterized in that, It contains a basic sealing material, microcapsules, and expanded graphite; wherein the microcapsules are microcapsules containing a sealing active substance, and the sealing active substance is an epoxy amino resin.

2. The multi-stage activation responsive differential pressure seal of claim 1, wherein, The basic sealing material is hydrogenated nitrile butadiene latex.

3. A method of making a multi-stage activation responsive differential pressure seal characterized by, The method includes: (1) Dissolve 10-20 parts by weight of toluene diisocyanate and 30-50 parts by weight of polyether polyol in 100 parts by weight of cyclohexanone to obtain a precursor solution; (2) Add 2 to 5 parts by weight of polyvinyl alcohol to 500 parts by weight of water to obtain a polyvinyl alcohol aqueous solution; (3) Mix 10-20 parts by weight of epoxy amino resin and 1-2 parts by weight of epoxy diluent to obtain the encapsulated liquid phase; (4) Add the precursor solution obtained in step (1) to the polyvinyl alcohol aqueous solution obtained in step (2), and add the encapsulating liquid phase obtained in step (3) under stirring conditions at 60-80°C to obtain microcapsules containing sealing active substances. (5) Add 1-3 parts by weight of the microcapsules containing the sealing active substance and 1-3 parts of expanded graphite to 100 parts of the base sealing material, and mix. (6) Add 5-10 parts by weight of activator and stir; add 1-2 parts by weight of terminator and stir; add 1-3 parts by weight of stabilizer and stir.

4. The method of claim 3, wherein, The basic sealing material is hydrogenated nitrile butadiene latex.

5. The method of claim 3, wherein, The epoxy diluent is an epoxy fatty acid ester.

6. The method of claim 3 wherein, The terminator is Span 80, and the stabilizer is potassium polyacrylate.

7. The method of claim 3 wherein, Step (6) Add the activator at a rate of ≤70 drops / minute.

8. The method of claim 3, wherein, Step (6) Add the activator at a rate of ≤40 drops / minute.

9. The method of claim 3 wherein, The activator is a magnesium chloride solution with a concentration of 0.1–0.3 g / L.

10. Use of a multi-stage activated response differential pressure sealant in plugging of oil and gas wells, characterized by, The multi-stage activated response differential pressure sealant is the multi-stage activated response differential pressure sealant according to any one of claims 1-2 or the multi-stage activated response differential pressure sealant prepared by any one of claims 3-9.