Expanding pressure-bearing leak-stopper, its preparation method and application

Abstract

This invention provides an intumescent pressure-bearing sealing agent, its preparation method, and its application. The intumescent pressure-bearing sealing agent, based on 100 wt%, comprises 10–48 wt% intumescent pressure-resistant material, 20–65 wt% oleophilic rigid particulate material, 0.1–10 wt% microporous fiber, and 0.5–30 wt% oil-absorbing flexible sealing material. The intumescent pressure-resistant material comprises a porous structure formed by thermosetting resin curing and water sealed within the porous structure. The pore size of the porous structure is 150 μm–300 μm, and the porosity of the intumescent pressure-resistant material is 8–25%. DSC measurement is used. The expandable and pressure-resistant material has a first weight loss peak within 100℃ to 300℃, a second weight loss peak within 350℃ to 380℃, and a third weight loss peak within 400℃ to 500℃; the weight loss rate of the expandable and pressure-resistant material at the first weight loss peak is <2.0%, the weight loss rate at the second weight loss peak is 2% to 32%, and the weight loss rate at the third weight loss peak is 33% to 61%; in this invention, the expandable and pressure-resistant material, the oleophilic rigid particulate material, the microporous fiber, and the oil-absorbing flexible sealing material form a dense leak-sealing wall, and the above four components work together to form a high-pressure-resistant and high-elasticity leak-sealing system.

Description

Technical Field

[0001] This invention relates to the field of oil well leakage prevention and plugging materials, specifically to an expandable pressure-bearing plugging agent and its preparation method and application. Background Technology

[0002] Bridging and sealing technology mainly utilizes a variety of sealing materials (such as granular, fibrous, and sheet materials) mixed in a specific ratio to prepare a sealing slurry. This slurry uses solid particles to block cracks and pore channels. Rigid particles act as bridges and supports in the leakage channels, while fibrous and sheet-like sealing agents connect and seal between the rigid particles. Deformable sealing agents primarily act as fillers, compressing and deforming to block the remaining pore spaces after the rigid particles, fibers, and sheet-like sealing agents have been sealed, thereby reducing permeability and achieving the purpose of sealing the leak.

[0003] Bridging and sealing technology is applicable to different types of well losses, but it is not suitable for all types of well losses. Especially when the location of the lost layer is unclear or the loss channel is complex, the effectiveness of bridging and sealing technology may be affected. The success or failure of bridging and sealing technology depends on whether the particle size ratio of the sealing agent is suitable for the diameter of the loss channel. If the particle size is too large, it cannot enter the fractures and pores; if the particle size is too small, it is not easy to form a bridge, thus affecting the sealing effect. Although there are many types of sealing materials, bridging and sealing mainly uses cement-based inorganic gels and composite bridging agents. These agents still have shortcomings in terms of water resistance and expansion properties, making it difficult to fully meet the needs of on-site construction.

[0004] The doctoral dissertation "Development and Leakage Prevention Mechanism Study of Temperature-Responsive Shape Memory Materials" published by Cui Kaixiao of China University of Petroleum (Beijing) synthesized a series of thermosetting unidirectional shape memory epoxy resin materials through a high-temperature cross-linking and curing reaction using epoxy resin E51, 4,4'-diaminodiphenylmethane curing agent, and hollow glass microsphere foaming agent. These materials were then hot-pressed to prepare temperature-sensitive, expandable shape memory leak-proof and sealing materials with adjustable response temperature and expansion rate. The glass transition temperature ranges from 36.40 to 142.6℃, the shape fixation rate is close to 100%, the shape recovery rate is greater than 90%, the shape recovery time decreases with increasing temperature, and the expansion rate ranges from 2.58% to 125.50%. Thermogravimetric analysis shows that the initial decomposition temperature of the material is greater than 230℃, indicating good thermal stability. Leakage prevention and sealing experiments show that the temperature-sensitive expandable shape memory leak-proof and sealing material has a good sealing effect on large-porosity sand beds and sand discs, with the sealing layer bearing pressure up to 5MPa.

[0005] Compared to water-based plugging, the challenge of oil-based plugging lies in the extremely low lubrication coefficient of oil, which makes it easy for the plugging material to slip off from the well wall and between the plugging materials themselves. Therefore, the retention requirements of the plugging material are higher.

[0006] Since the temperature-responsive shape memory materials mentioned in the above literature are still in the basic research stage and the process is relatively complex, they have not yet been specifically applied in the field of oil drilling leak prevention and plugging. Therefore, there is an urgent need to develop an oil-based leak-plugging expansion pressure-bearing agent with stable mechanical properties at high temperatures and a simple preparation process. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems of complex preparation process and low industrialization level of high temperature shape memory composite materials and extremely low oil-based lubrication coefficient in the prior art. It provides an expansion pressure-bearing sealing agent, its preparation method and application. The expansion pressure-bearing material of the sealing agent has a high proportion of volume expansion, which has strong adaptability to filling and sealing space, good viscosity retention effect, and significantly improved mechanical strength and good density and significantly reduced leakage when the above sealing agent is used.

[0008] To achieve the above objectives, the first aspect of the present invention provides an intumescent pressure-bearing sealing agent, which, based on 100 wt% of the intumescent pressure-bearing sealing agent, comprises 10-48 wt% intumescent pressure-resistant material, 20-65 wt% in oleophilic rigid particulate material, 0.1-10 wt% in microporous fiber, and 0.5-30 wt% in oil-absorbing flexible sealing material.

[0009] The expansion and pressure-resistant material comprises a porous structure formed by curing a thermosetting resin and water sealed in the porous structure; the pore size of the porous structure is 150μm to 300μm, and the porosity of the expansion and pressure-resistant material is 8 to 25%.

[0010] DSC measurements showed that the expandable compressive-resistant material had a first weight loss peak in the range of 100℃ to 300℃, a second weight loss peak in the range of 350℃ to 380℃, and a third weight loss peak in the range of 400℃ to 500℃; the weight loss rate of the expandable compressive-resistant material at the first weight loss peak was <2.0%, the weight loss rate at the second weight loss peak was 2% to 32%, and the weight loss rate at the third weight loss peak was 33% to 61%.

[0011] The method for preparing the expansion-resistant compressive material includes the following steps:

[0012] Preparation of the first mixture S1: The thermosetting resin is mixed with the first curing agent to obtain the first mixture;

[0013] Preparation of the second mixture S2: Mix the second curing agent with water to obtain the second mixture;

[0014] Preparation of the third mixture S3: Mix the first mixture and the second mixture evenly, add the accelerator and foaming agent, and stir for ≥10 minutes at 60℃~85℃ and 0.3~3MPa with the speed adjusted to 700rpm~3000rpm to obtain the third mixture;

[0015] S4 curing: The third mixture is cured at 0.3 to 3 MPa to obtain the expansion and pressure-resistant material.

[0016] Compared to water-based plugging, the challenge of oil-based plugging lies in the extremely low lubricity coefficient of oil, which makes it easy for the plugging material to slip off between itself and the wellbore, as well as between the plugging materials themselves. Therefore, in addition to the functions of water-based plugging systems, oil-based plugging places higher demands on the retention properties of the plugging materials, requiring further enhancement of the adhesion and retention effects between the plugging materials and between the plugging materials and the wellbore.

[0017] The thermosetting resin of the expanding and pressure-resistant material in the plugging agent of the present invention is cured to form a porous structure. This porous structure seals water within the expanding and pressure-resistant material. By controlling the pore size of the porous structure and the porosity of the expanding and pressure-resistant material, an expanding and pressure-resistant material with both rigidity and flexibility is formed. In a wellbore environment with a temperature of 100°C or higher, the water in this expanding and pressure-resistant material reaches its boiling point and boils, expanding in volume. The expanding and pressure-resistant material in the plugging agent is combined with oleophilic rigid particulate material, microporous fiber, and oil-absorbing flexible plugging material. The oleophilic rigid particulate material in the plugging agent can stably bridge the fractures, forming a framework for sealing the formation. The rigid structure of these particles enables them to resist formation pressure, thereby forming a stable and durable sealing layer at the fracture. The use of a smaller microporous fiber mesh structure provides better retention performance for the plugging agent in the initial stage. The oil-absorbing flexible plugging material has a good expansion self-adaptive plugging effect after absorbing oil. The surface viscosity of the expansion and pressure-resistant material is activated at high temperature, which firmly adheres to the well wall and binds the oleophilic rigid particle material, microporous fiber and oil-absorbing flexible plugging material to form a dense plugging wall. The above four components work together to form a high pressure-resistant and high elastic plugging system.

[0018] It is believed that the relatively flat first weight loss peak at 100℃ to 300℃ may be obtained by the evaporation of water adsorbed on the surface of the expansion and compression-resistant material; the second weight loss peak at 350℃ to 380℃ may be obtained by the rapid evaporation of water sealed in the material after the structure of the expansion and compression-resistant material is destroyed by high temperature heating; and the third weight loss peak at more than 400℃ may be the decomposition and vaporization of the non-aqueous components of the expansion and compression-resistant material.

[0019] In step S1, the thermosetting resin undergoes a crosslinking reaction with the first curing agent to obtain a pre-crosslinked body. In step S3, the second curing agent is added to the pre-crosslinked body, mixed evenly, and then an accelerator and a foaming agent are added before pressure curing. Adding the first and second curing agents in steps, with the thermosetting resin and the first curing agent forming the pre-crosslinked body first, allows for easier control of the crosslinking reaction rate and direction compared to adding both simultaneously. Furthermore, the resulting pre-crosslinked body and the second curing agent are more evenly distributed, resulting in a high-temperature mechanical strength in the prepared intumescent and pressure-resistant material, and strong sealing ability for functional water.

[0020] The preparation of the third mixture under high pressure ensures closer contact between the first and second mixtures, facilitating further cross-linking and improving reaction efficiency. Under pressure, the wetting effect of the thermosetting resin is enhanced, resulting in a more uniform distribution of the pre-crosslinked body and the second curing agent obtained in step S1. This leads to higher high-temperature mechanical strength and stronger sealing ability of the resulting intumescent compressive strength material. Pressure curing significantly improves the structural density of the intumescent compressive strength material, prevents delamination and bubble formation during curing, and enhances the material's mechanical strength and sealing ability. Furthermore, the pressure curing process allows for precise control of the resin content in the intumescent compressive strength material by controlling the pressure, extruding excess resin and thus ensuring more stable performance and structure.

[0021] In some embodiments of the present invention, the expanding pressure-bearing sealing agent comprises, at 100 wt%, 20-35 wt% expanding pressure-resistant material, 40-60 wt% oleophilic rigid particulate material, 0.1-8 wt% microporous fiber, and 1-25 wt% oil-absorbing flexible sealing material.

[0022] In some embodiments of the present invention, the thermosetting resin comprises one or more of epoxy resin, phenolic resin, polyetherketone resin, and polyimide resin.

[0023] In some embodiments of the present invention, the pore size of the porous structure is 200 μm to 280 μm, and the porosity of the expansion and compressive strength material is 10 to 20%.

[0024] In some embodiments of the present invention, in step S1, the thermosetting resin is heated to 60°C to 85°C, the first curing agent is added, the temperature is adjusted to 5°C to 30°C above the melting point of the first curing agent, and after the first curing agent is completely dissolved, it is stirred at a stirring speed of 200 to 400 rpm for 20 to 60 minutes, and then adjusted to 60°C to 85°C to obtain the first mixture.

[0025] In some embodiments of the present invention, step S2 includes step S2-1, step S2-2 or step S2-3;

[0026] Step S2-1: The second curing agent is a solid with a melting point ≥90℃. Add the second curing agent to the solution and adjust the temperature to 5℃~30℃ above the melting point of the second curing agent. After the second curing agent is completely dissolved, adjust the temperature to 60℃~85℃, add water, and stir at a stirring speed of 200~400rpm for 20~60min to obtain the second mixture.

[0027] Step S2-2: The second curing agent is a solid with a melting point <90℃. Add the second curing agent to water and heat it to 5℃~10℃ above the melting point of the second curing agent. After the second curing agent is completely dissolved, adjust the temperature to 60℃~85℃ and stir at a stirring speed of 200~400rpm for 20~60min to obtain the second mixture.

[0028] Step S2-3: The second curing agent is a liquid. Adjust the temperature to 60℃~85℃, add water to the second curing agent, and stir at a stirring speed of 200~400rpm for 20~60min to obtain the second mixture.

[0029] In some embodiments of the present invention, in step S3, nitrogen gas is introduced to pressurize the mixture, the second mixture is added to the first mixture, an accelerator and a foaming agent are added, and the mixture is stirred for 10-30 minutes to obtain a third mixture.

[0030] In some embodiments of the present invention, in step S4, the pressure curing includes two or all three of the following: first curing, second curing, and third curing; the first curing is carried out at a constant temperature of 100℃~110℃ for 2h~8h; the second curing is carried out at a constant temperature of 120℃~130℃ for 0.5h~4h; and the third curing is carried out at a constant temperature of 140℃~160℃ for 0.5h~4h.

[0031] In some embodiments of the present invention, the first curing agent and the second curing agent may be the same or different, and each is independently selected from one or more of acid anhydride curing agents, phenolic curing agents, and aromatic polyamine curing agents.

[0032] In some embodiments of the present invention, the mass ratio of the first curing agent to the second curing agent is (0.60-3):1.

[0033] In some embodiments of the present invention, the amount of thermosetting resin is 100 parts by weight, the total amount of the first curing agent and the second curing agent is 50 to 100 parts by weight, the amount of accelerator is 0 to 2 parts by weight, the amount of water is 10 to 50 parts by weight, and the amount of foaming agent is 0.1 to 3 parts by weight.

[0034] In this invention, by further adjusting the dosage of each component in the expanding and pressure-resistant material of the sealing agent, the expanding and pressure-resistant material in the sealing agent has a stronger self-adaptive ability, changing the linear expansion of the resin to a high proportion of volumetric expansion, which significantly improves the expansion rate of the sealing agent; and significantly improves the mechanical properties of the sealing agent after expansion, changing the defects of the previous material expansion, which was loose in structure and decreased in mechanical properties, so that the expanding and pressure-resistant material still has high compressive and shear resistance after expansion at high temperature, combining the advantages of rigid and flexible sealing.

[0035] In some embodiments of the present invention, the amount of the solution used is 10 to 20 parts by weight.

[0036] In some embodiments of the present invention, the solution contains at least one of a liquid resin curing agent and a liquid resin toughening agent.

[0037] In some embodiments of the present invention, the solution contains at least one of a modified aromatic amine liquid curing agent, a modified phenolic high-temperature curing agent, and an alkenyl succinic anhydride.

[0038] In some embodiments of the present invention, the epoxy resin in the expanding and compressive material comprises one or more of glycidyl ether epoxy resin, glycidyl amine epoxy resin, glycidyl ester epoxy resin, imide-modified epoxy resin, and phenolic-modified epoxy resin.

[0039] In some embodiments of the present invention, the epoxy resin comprises one or more of bisphenol A diglycidyl ether, phenolic epoxy resin, and imide epoxy resin.

[0040] In some embodiments of the present invention, the epoxy resin comprises one or both of bisphenol A diglycidyl ether E51 and phenolic epoxy resin F51.

[0041] In some embodiments of the present invention, the anhydride curing agent comprises one or more of maleic anhydride, alkenyl succinic anhydride, phthalic anhydride, cyclopentetrate dianhydride, and methyl hexahydrophthalic anhydride.

[0042] In some embodiments of the present invention, the curing agent comprises one or two of the following: modified phenolic high-temperature curing agent F-52B or F-51A, and modified aromatic amine liquid curing agent VT5327.

[0043] In some embodiments of the present invention, the accelerator comprises one or more of triethanolamine, dimethylaniline, and 2,4,6-tris(dimethylaminomethyl)phenol.

[0044] In some embodiments of the present invention, the water is fresh water or salt water.

[0045] In some embodiments of the present invention, a foam enhancer is added to the water.

[0046] In some embodiments of the present invention, the foam enhancer comprises one or both of a surfactant or a thickening and shearing agent; the mass content of the foam enhancer is 0.1% to 1% based on the weight of the water.

[0047] In some embodiments of the present invention, the surfactant-based foam enhancer comprises one or more of polysorbate, sorbitan monooleate, oleyl alcohol polyoxyethylene ether, and dodecyl oleate.

[0048] In some embodiments of the present invention, the thickening and cutting agent-type foam reinforcing agent comprises one or more of hydroxyethyl methyl cellulose, polyacrylamide, and sodium carboxymethyl starch.

[0049] In some embodiments of the present invention, the foaming agent comprises one or more of anionic foaming agents, cationic foaming agents, and nonionic foaming agents.

[0050] In some embodiments of the present invention, the foaming agent is an anionic foaming agent, preferably comprising one or more of sodium dodecylbenzenesulfonate, fatty alcohol glyceryl ether sulfonate, or α-olefin sulfonate.

[0051] The oleophilic rigid particulate material in the sealant of this invention is mainly used to improve the pressure-bearing capacity of the sealant. Especially in projects with greater depth, the sealant needs to provide greater pressure-bearing capacity. The oleophilic rigid particulate material bridges at the crack to provide pressure-bearing capacity.

[0052] In some embodiments of the present invention, the oleophilic rigid particulate material is selected from at least one of geological-based polymers and modified minerals.

[0053] In some embodiments of the present invention, the oleophilic rigid particulate material is selected from at least one of limestone, quartz sand, volcanic rock, and silicon carbide. The selection of these oleophilic rigid particles ensures good compatibility with drilling mud, and their use in plugging leaks does not affect the performance of the drilling mud, which helps maintain the stability and fluidity of the drilling fluid.

[0054] In some embodiments of the present invention, the oleophilic rigid particulate material is composed of irregularly shaped rigid particles and spherical rigid particles, wherein the mass ratio of the irregularly shaped rigid particles to the spherical rigid particles is 1:(1-4). The irregularly shaped rigid particles are wedged into the formation and bridged with microporous fibers to form a network, improving the frictional properties of the plugging agent, enhancing the initial retention performance of the plugging material and the bonding between the plugging materials, and preventing the expanding pressure-resistant material from being effectively retained on the wellbore before expanding after reaching the leakage space.

[0055] In some embodiments of the present invention, the particle size of the oleophilic rigid particulate material is selected from at least three gradations selected from 1-2 mm, 3-5 mm, 6-10 mesh, 10-20 mesh, 30-50 mesh, 60-80 mesh, 100-150 mesh, 200-400 mesh, and 400-800 mesh.

[0056] The role of microporous fibers in the plugging agent of this invention is as follows: 1) They can overlap with other components to form a network structure to improve the retention performance of the plugging agent. Especially in the early stage of plugging, when the expansion and pressure-resistant material has not yet reached a certain expansion rate, the plugging agent is easy to move in the larger leakage space and is not easy to be retained; 2) The network structure formed by the fibers can work together with the oleophilic rigid particle material to improve the overall pressure-bearing effect of the plugging agent; 3) The microporous structure enhances the oil absorption and filling effect. The microporous structure can easily accept small-diameter particles for filling and is easy to adhere to and be retained on the well wall. Its binding and retention effect is good.

[0057] In some embodiments of the present invention, the microporous fiber is selected from at least one of microporous oil-absorbing plant fibers, mineral fibers, and polyester fibers.

[0058] In some embodiments of the present invention, the microporous fiber is selected from at least one of aluminosilicate fiber, polysilicon fiber, sepiolite fiber, basalt fiber, ceramic fiber, polyvinyl alcohol fiber, and polyimide fiber. Selecting the above-mentioned microporous fibers results in better oil absorption and filling effects, as the micropores of these materials more readily accommodate small-diameter particles, further enhancing the retention effect.

[0059] In some embodiments of the present invention, the pore size of the microporous fiber is 0.1 mm to 0.5 mm; the fiber length is selected from at least one of 1 to 3 mm, 3 to 5 mm, 5 to 7 mm, 7 to 10 mm, and 12 to 15 mm.

[0060] In some embodiments of the present invention, the oil-absorbing flexible plugging material is selected from at least one of oleophilic plugging materials, oil-soluble plugging materials, or high-temperature melt coating materials.

[0061] In some embodiments of the present invention, the oil-absorbing flexible sealing material is selected from at least one of oil-absorbing expanding rubber, oil-absorbing expanding resin, silicone-modified acrylate, and coal tar pitch.

[0062] In some embodiments of the present invention, the expansion ratio of the oil-absorbing flexible sealing material is 0.5 to 1.5.

[0063] In some embodiments of the present invention, the oil-absorbing flexible sealing material is micron-sized particles with a particle size range of 0.5 to 200 μm.

[0064] The oil-absorbing flexible sealing material in the sealant of this invention improves the pressure resistance and buffering effect. It can fill the fine pores through compression, contributing to the formation of a denser sealing layer. The oil-absorbing flexible sealing material is an oil-absorbing and expanding sealing material, which enhances the expansion-adaptive sealing effect while further improving the density of the sealing layer. Choosing the above-mentioned oil-absorbing flexible sealing material results in better pressure resistance and buffering effect, as it can be better dispersed in the fine pores. Furthermore, selecting an appropriate particle size range further facilitates the dispersion of flexible particles. The above-mentioned oil-absorbing flexible sealing materials all have a certain expansion capacity after absorbing oil, and by compression, the oil-absorbing flexible sealing material can fully fill the fine pores.

[0065] The second aspect of the present invention provides a method for preparing an expandable pressure-bearing sealing agent, comprising the following steps: mixing an expandable pressure-resistant material, an oleophilic rigid particulate material, a microporous fiber, and an oil-absorbing flexible sealing material to obtain the expandable pressure-bearing sealing agent.

[0066] In some embodiments of the present invention, the stirring rate is 300-1000 r / min; the stirring time is 5-20 min; and the mixing temperature is 50-90℃.

[0067] A third aspect of the present invention provides a method for sealing leaks using the above-described expanding pressure-bearing sealing agent or the expanding pressure-bearing sealing agent prepared by the above-described method, comprising the following steps:

[0068] In oil-based sealing, the sealing agent is added to a container with a temperature of 100-260℃ and a density of 1.5-2.4 g / cm³. 3 In the drilling fluid, the amount of the plugging agent is 10% to 50% (w / v).

[0069] The technical solution provided by this invention has the following beneficial effects:

[0070] 1. The thermosetting resin of the expanding and pressure-resistant material in the plugging agent of the present invention is cured to form a porous structure. This porous structure seals water within the expanding and pressure-resistant material. By controlling the pore size of the porous structure and the porosity of the expanding and pressure-resistant material, an expanding and pressure-resistant material with both rigidity and flexibility is formed. In a wellbore environment with a temperature of 100°C or higher, the water in this expanding and pressure-resistant material reaches its boiling point and boils, causing it to expand in volume. The expanding and pressure-resistant material, the oleophilic rigid particle material, the microporous fiber, and the oil-absorbing flexible plugging material in the plugging agent work together. The oleophilic rigid particle material in the plugging agent can stably bridge the fractures, forming a framework for sealing the formation. The rigid structure of these particles enables them to resist formation pressure, thereby forming a stable and durable sealing layer at the fracture. The network structure of microporous fibers provides initial retention performance for the plugging agent. The surface viscosity of the expanding and pressure-resistant material is activated at high temperature, which firmly adheres to the well wall and binds the oleophilic rigid particulate material, microporous fibers and oil-absorbing flexible plugging material to form a dense plugging wall. The above four components work together to form a plugging system with high pressure resistance and high elasticity.

[0071] 2. In step S1, the thermosetting resin undergoes a crosslinking reaction with the first curing agent to obtain a pre-crosslinked body. In step S3, the second curing agent is added to the pre-crosslinked body, mixed evenly, and then an accelerator and a foaming agent are added before pressure curing. Adding the first and second curing agents in steps, with the thermosetting resin and the first curing agent forming the pre-crosslinked body first, allows for easier control of the crosslinking reaction rate and direction compared to adding both simultaneously. Furthermore, the resulting pre-crosslinked body and the second curing agent are more evenly distributed, resulting in a high-temperature mechanical strength in the prepared intumescent and pressure-resistant material, and strong sealing ability for functional water.

[0072] 3. The preparation of the third mixture under high pressure ensures closer contact between the first and second mixtures, facilitating further cross-linking and improving reaction efficiency. Under pressure, the wetting effect of the thermosetting resin is enhanced, resulting in a more uniform distribution of the pre-crosslinked body obtained in step S1 and the second curing agent. This leads to a higher expansion temperature, higher high-temperature mechanical strength, higher porosity, and stronger sealing ability of the functional water in the resulting intumescent and pressure-resistant material. Pressure curing significantly improves the structural density of the intumescent and pressure-resistant material, prevents delamination and bubble formation during curing, and enhances the material's expansion temperature, mechanical strength, and sealing ability. The faster pressure curing process seals in more functional water, and the resin content in the intumescent and pressure-resistant material can be precisely controlled by adjusting the pressure, squeezing out excess resin and thus making its performance and structure more stable. Detailed Implementation

[0073] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified, specific conditions in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the materials used in the embodiments are commercially available products or conventional products that can be synthesized by known methods.

[0074] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0075] The main reagents used in this invention are as follows:

[0076] Bisphenol A diglycidyl ether E51 was purchased from Hubei Dongcao Chemical Technology Co., Ltd., CAS No. 1675-54-3.

[0077] The phenolic epoxy resin F51 was purchased from Nantong Xingchen Synthetic Materials Co., Ltd.

[0078] Maleic anhydride was purchased from Sinopharm Group, CAS number 108-31-6.

[0079] The alkenyl succinic anhydride (ASA) was purchased from Guangzhou Haoyi New Material Technology Co., Ltd., CAS No. 26544-38-7.

[0080] Phthalic anhydride (PA) was purchased from Shandong Sanju Chemical Technology Co., Ltd., CAS No. 85-44-9.

[0081] The modified phenolic high-temperature curing agent F-52B was purchased from Bengbu Tianyu High-Temperature Resin Materials Co., Ltd.

[0082] The modified aromatic amine liquid curing agent VT5327 was purchased from Shenzhen Huite Chemical Co., Ltd.

[0083] VT5327 is a liquid modified aromatic amine curing agent, a yellow to brown viscous liquid, mainly used as a high-temperature curing agent for epoxy resins.

[0084] Sodium dodecylbenzenesulfonate (SDBS) was purchased from Shandong Yongwang Chemical Co., Ltd., CAS No. 25155-30-0.

[0085] Sodium α-olefin sulfonate (AOS) was purchased from China National Light Industry Chemical Co., Ltd., CAS No. 68439-57-6.

[0086] The cetyltrimethylammonium bromide (CTAB) was purchased from Shandong Xiya Chemical Co., Ltd., CAS No. 57-09-0.

[0087] The aluminum silicate fiber was purchased from Hebei Huaou Energy Saving Technology Group Co., Ltd.

[0088] Sepiolite fiber was purchased from Lingshou County Hefeng Mineral Products Co., Ltd.

[0089] The oil-absorbing and expanding rubber was purchased from Dongguan Caihua Plastics Technology Co., Ltd., and the fluororubber / ABS was recycled. (Temperature resistance 240°C)

[0090] The silicone-modified acrylic resin was purchased from UGREEN (Jining) Chemical Technology Co., Ltd., CAS9003-01-4.

[0091] Coal tar pitch was purchased from Hebei Fengtaiyuan Energy Technology Co., Ltd., CAS No. 8052-42-4.

[0092] The preparation method of thermosensitive shape memory polymer particles is as follows: The thermosensitive shape memory polymer (styrene-butyl acrylate copolymer with a shape memory deformation temperature of 50–110℃, purchased from Texas Continental Shelf Petroleum Engineering Technology Co., Ltd.) is cryogenically frozen with liquid nitrogen at a temperature of -10℃ to -20℃. The fibers are polypropylene fibers (polypropylene fiber) and polyvinyl chloride fibers (chlorofiber) in a weight ratio of 50% each. The fibers and thermosensitive shape memory polymer powder in a 1:1 weight ratio are mixed uniformly using a high-speed mixer. The uniformly mixed material is then granulated using an extrusion granulator, with the extrusion granulation temperature set at 55–75℃.

[0093] The testing method used in this invention:

[0094] 1. Test methods for pore size and porosity

[0095] The expansion and compressive strength materials prepared in the examples and comparative examples were made into test samples according to a mold with specifications of 60mm×60mm×30mm. The samples were subjected to liquid nitrogen brittle fracture, and the surface morphology of the samples was observed using a Hitachi S4800 field emission scanning electron microscope to obtain their pore size and porosity.

[0096] 2. Test method for weightlessness rate

[0097] The mass of the expansion and compressive strength material prepared in the test examples and comparative examples is recorded as m1. The expansion and compressive strength material is heated to 100-300℃ at a rate of 5℃ / min, maintained at the high temperature for 4-5 hours, removed and cooled to room temperature, and its mass is recorded as m2. The first weight loss rate is calculated according to the formula: First weight loss rate = 100(m1-m2) / m1. The expansion and compressive strength material is heated to 320-380℃ at a rate of 5℃ / min, maintained at the high temperature for 4-5 hours, removed and cooled to room temperature, and its mass is recorded as m3. The second weight loss rate is calculated according to the formula: Second weight loss rate = 100(m2-m3) / m2. The expansion and compressive strength material is heated to 400-500℃ at a rate of 5℃ / min, maintained at the high temperature for 3-4 hours, removed and cooled to room temperature, and its mass is recorded as m4. The third weight loss rate is calculated according to the formula: Third weight loss rate = 100(m4-m3) / m3.

[0098] Preparation Example 1

[0099] Preparation Example 1-1 provides a method for preparing an expansion-resistant compressive material.

[0100] Preparation of the first mixture S1: Heat 100g of bisphenol A diglycidyl ether E51 to 60℃ and maintain the temperature for 10min. After the bisphenol A diglycidyl ether E51 becomes thin, add 20g of maleic anhydride while stirring at 300rpm. Adjust the temperature to 85℃. After the maleic anhydride dissolves, add 12g of alkenyl succinic anhydride. Continue stirring for 40min and adjust the temperature to 60℃ to obtain the first mixture.

[0101] Preparation of the second mixture S2: Add 33g of maleic anhydride to 30mL of water, adjust the temperature to 85℃, and keep stirring at 200rpm until the maleic anhydride is completely dissolved. Then add 20g of alkenyl succinic anhydride and adjust the temperature to 60℃ to obtain the second mixture.

[0102] Preparation of the third mixture S3: Add the second mixture to the first mixture, mix evenly, then add 1.1g of dimethylaniline and 0.25g of sodium dodecylbenzenesulfonate. Stir for 10 minutes at 60℃ and 1.0MPa with a rotation speed of 1000rpm to obtain the third mixture.

[0103] S4 Curing: Brush silicone oil onto the mold surface, put the third mixture into the mold, place the mold in a preheated constant temperature box, keep it at 120℃ for 2 hours under normal pressure (0.1MPa), and then raise the temperature to 150℃ for 1 hour to complete the curing; after the cured body cools down, the cured body board is obtained, and after demolding, it is crushed into different particle sizes to obtain the expansion and compressive strength material.

[0104] Preparation Example 1-1 prepared an intumescent compressive strength material comprising a porous structure formed by the curing of a thermosetting resin and water sealed within the porous structure; the pore size of the porous structure is 230–280 μm, and the porosity of the intumescent compressive strength material is 14.78%; using DSC measurement, at 200–270 °C, the weight loss of the intumescent compressive strength material at the first weight loss peak is 1.50%; at 360–370 °C, the weight loss of the intumescent compressive strength material at the second weight loss peak is 25.9%; above 400 °C, the weight loss of the intumescent compressive strength material at the third weight loss peak is 56.3%.

[0105] Preparation Examples 1-2 provide a method for preparing an expansion-resistant compressive material.

[0106] The expansion-resistant material was prepared according to the method described in Preparation Example 1-1, except that in Preparation Example 1-2, nitrogen gas was introduced in step S3 and the pressure was maintained at 0.3 MPa; in step S4, pressure curing was performed and the pressure was maintained at 0.3 MPa.

[0107] The intumescent compressive strength materials prepared in Examples 1-2 comprise a porous structure formed by the curing of a thermosetting resin and water sealed within the porous structure. The pore size of the porous structure is 220–230 μm, and the porosity of the intumescent compressive strength material is 16.84%. DSC measurements show that at 200–270 °C, the weight loss of the intumescent compressive strength material at the first weight loss peak is 1.4%; at 360–370 °C, the weight loss at the second weight loss peak is 28.2%; and above 400 °C, the weight loss at the third weight loss peak is 58.2%.

[0108] Preparation Examples 1-3 provide a method for preparing an expansion-resistant compressive material.

[0109] The expansion-resistant material was prepared according to the method described in Preparation Example 1-1, except that in Preparation Example 1-3, nitrogen gas was introduced in step S3 and the pressure was maintained at 1.0 MPa; in step S4, pressure curing was performed and the pressure was maintained at 1.0 MPa.

[0110] The intumescent compressive strength materials prepared in Examples 1-3 comprise a porous structure formed by the curing of a thermosetting resin and water sealed within the porous structure. The pore size of the porous structure is 210–220 μm, and the porosity of the intumescent compressive strength material is 18.96%. DSC measurements show that at 200–270 °C, the weight loss of the intumescent compressive strength material at the first weight loss peak is 1.2%; at 360–370 °C, the weight loss at the second weight loss peak is 30.8%; and above 400 °C, the weight loss at the third weight loss peak is 60.5%.

[0111] Preparation Example 2

[0112] Preparation Example 2-1 provides a method for preparing an expansion-resistant compressive material.

[0113] Preparation of the first mixture S1: Heat 60g of bisphenol A diglycidyl ether E51 to 60℃ and add 40g of phenolic epoxy resin F51. After maintaining the temperature for 10min, when the bisphenol A diglycidyl ether E51 and phenolic epoxy resin F51 become thin, add 20g of alkenyl succinic anhydride and 12g of modified phenolic high-temperature curing agent F-52B while stirring at 300rpm. Adjust the temperature to 85℃ and continue stirring for 40min. Adjust the temperature to 60℃ to obtain the first mixture.

[0114] Preparation of the second mixture S2: Mix 28g of alkenyl succinic anhydride and 16g of modified phenolic high-temperature curing agent F-52B evenly, adjust the temperature to 85℃, maintain a stirring speed of 200rpm, add 30mL of water while stirring, and adjust the temperature to 60℃ to obtain the second mixture.

[0115] Preparation of the third mixture S3: Add the second mixture to the first mixture, mix well, then add 1.2g of 2,4,6-tris(dimethylaminomethyl)phenol and 0.25g of sodium α-olefin sulfonate. Stir for 10 minutes at 60℃ and 2.0MPa with a speed of 2000rpm to obtain the third mixture.

[0116] S4 Curing: Brush silicone oil on the mold surface, put the third mixture into the mold, put the mold into a preheated constant temperature box, keep it at 120℃ for 3 hours under normal pressure (0.1MPa), and then raise the temperature to 150℃ for 1 hour to complete the curing; after the cured body cools down, the cured body board is obtained, and after demolding, it is crushed into different particle sizes to obtain the expansion and compressive strength material.

[0117] Preparation Example 2-1 prepared an intumescent compressive material comprising a porous structure formed by the curing of a thermosetting resin and water sealed within the porous structure; the pore size of the porous structure is 230–280 μm, and the porosity of the intumescent compressive material is 10.95%; using DSC measurement, at 200–270 °C, the weight loss of the intumescent compressive material at the first weight loss peak is 1.8%; at 360–370 °C, the weight loss of the intumescent compressive material at the second weight loss peak is 15.8%; above 400 °C, the weight loss of the intumescent compressive material at the third weight loss peak is 51.8%.

[0118] Preparation Example 2-2 provides a method for preparing an expansion-resistant compressive material.

[0119] The expansion-resistant material was prepared according to the method described in Preparation Example 2-1, except that in Preparation Example 2-2, nitrogen gas was introduced in step S3 and the pressure was maintained at 1.0 MPa; in step S4, pressure curing was performed and the pressure was maintained at 1.0 MPa.

[0120] Preparation Example 2-2 prepared an intumescent compressive strength material comprising a porous structure formed by the curing of a thermosetting resin and water sealed within the porous structure; the pore size of the porous structure is 220–230 μm, and the porosity of the intumescent compressive strength material is 12.82%; using DSC measurement, at 200–270 °C, the weight loss of the intumescent compressive strength material at the first weight loss peak is 1.5%; at 360–370 °C, the weight loss of the intumescent compressive strength material at the second weight loss peak is 18.2%; above 400 °C, the weight loss of the intumescent compressive strength material at the third weight loss peak is 53.4%.

[0121] Preparation Example 2-3 provides a method for preparing an expansion-resistant compressive material.

[0122] The expansion-resistant material was prepared according to the method described in Preparation Example 2-1, except that in Preparation Example 2-3, nitrogen gas was introduced in step S3 and the pressure was maintained at 2.0 MPa; in step S4, pressure curing was performed and the pressure was maintained at 2.0 MPa.

[0123] The intumescent compressive strength materials prepared in Examples 2-3 comprise a porous structure formed by the curing of a thermosetting resin and water sealed within the porous structure. The pore size of the porous structure is 210–220 μm, and the porosity of the intumescent compressive strength material is 14.61%. DSC measurements show that at 200–270 °C, the weight loss of the intumescent compressive strength material at the first weight loss peak is 1.3%; at 360–370 °C, the weight loss at the second weight loss peak is 20.6%; and above 400 °C, the weight loss at the third weight loss peak is 55.3%.

[0124] Preparation Example 3

[0125] Preparation Example 3-1 provides a method for preparing an expansion-resistant compressive material.

[0126] Preparation of the first mixture S1: Heat 100g of bisphenol A diglycidyl ether E51 to 85℃ and maintain the temperature for 10min. After the bisphenol A diglycidyl ether E51 becomes thin, add 20g of phthalic anhydride PA while stirring at 300rpm. Adjust the temperature to 135℃ and add 12g of modified aromatic amine liquid curing agent VT5327. After the phthalic anhydride PA is completely dissolved, continue stirring for 20min and adjust the temperature to 85℃ to obtain the first mixture.

[0127] Preparation of the second mixture S2: Add 35g of phthalic anhydride PA to 18g of modified aromatic amine liquid curing agent VT5327, adjust the temperature to 135℃, maintain a stirring speed of 200rpm until the phthalic anhydride PA is completely dissolved, adjust the temperature to 85℃, and then add 40mL of water while stirring to obtain the second mixture.

[0128] Preparation of the third mixture S3: Add the second mixture to the first mixture, mix well, then add 1.2g of 2,4,6-tris(dimethylaminomethyl)phenol and 0.50g of sodium α-olefin sulfonate. Stir for 10 minutes at 85℃ and 1.3MPa with a speed of 2000rpm to obtain the third mixture.

[0129] S4 Curing: Brush silicone oil onto the mold surface, put the third mixture into the mold, place the mold in a preheated constant temperature box, keep it at 120℃ for 2 hours under normal pressure (0.1MPa), and then raise the temperature to 150℃ for 1 hour to complete the curing; after the cured body cools down, the cured body board is obtained, and after demolding, it is crushed into different particle sizes to obtain the expansion and compressive strength material.

[0130] Preparation Example 3-1 prepared an intumescent compressive material comprising a porous structure formed by the curing of a thermosetting resin and water sealed within the porous structure; the pore size of the porous structure is 230–280 μm, and the porosity of the intumescent compressive material is 14.57%; using DSC measurement, at 200–270 °C, the weight loss of the intumescent compressive material at the first weight loss peak is 1.0%; at 360–370 °C, the weight loss of the intumescent compressive material at the second weight loss peak is 24.5%; above 400 °C, the weight loss of the intumescent compressive material at the third weight loss peak is 45.3%.

[0131] Preparation Example 3-2 provides a method for preparing an expansion-resistant compressive material.

[0132] The expansion-resistant material was prepared according to the method described in Preparation Example 3-1, except that in Preparation Example 3-2, nitrogen gas was introduced in step S3 and the pressure was maintained at 0.5 MPa; in step S4, pressure curing was performed and the pressure was maintained at 0.5 MPa.

[0133] The intumescent compressive strength material prepared in Example 3-2 comprises a porous structure formed by the curing of a thermosetting resin and water sealed within the porous structure; the pore size of the porous structure is 220–230 μm, and the porosity of the intumescent compressive strength material is 16.54%; using DSC measurement, at 200–270 °C, the weight loss of the intumescent compressive strength material at the first weight loss peak is 1.0%; at 360–370 °C, the weight loss of the intumescent compressive strength material at the second weight loss peak is 26.8%; above 400 °C, the weight loss of the intumescent compressive strength material at the third weight loss peak is 47.2%.

[0134] Preparation Example 3-3 provides a method for preparing an expansion-resistant compressive material.

[0135] The expansion-resistant material was prepared according to the method described in Preparation Example 3-1, except that in Preparation Example 3-3, nitrogen gas was introduced in step S3 and the pressure was maintained at 1.3 MPa; in step S4, pressure curing was performed and the pressure was maintained at 1.3 MPa.

[0136] Preparation Example 3-3 prepared an intumescent compressive strength material comprising a porous structure formed by the curing of a thermosetting resin and water sealed within the porous structure; the pore size of the porous structure is 210–220 μm, and the porosity of the intumescent compressive strength material is 18.52%; using DSC measurement, at 200–270 °C, the weight loss of the intumescent compressive strength material at the first weight loss peak is 0.9%; at 360–370 °C, the weight loss of the intumescent compressive strength material at the second weight loss peak is 28.9%; above 400 °C, the weight loss of the intumescent compressive strength material at the third weight loss peak is 50.6%.

[0137] Example 1

[0138] 1. Preparation method of expansion pressure-bearing sealing agent

[0139] The expansion and compressive strength materials prepared in Examples 1-3 were pulverized and sieved to obtain particulate materials with a particle size of 20-40 mesh.

[0140] The following ingredients are mixed: 3 parts by weight of intumescent pressure-resistant material (20-40 mesh), 5 parts by weight of irregular volcanic rock (1-2 mm), 2 parts by weight of silicon carbide (10-20 mesh), 3 parts by weight of limestone (30-50 mesh), 3 parts by weight of limestone (60-80 mesh), 2 parts by weight of limestone (100-150 mesh), 0.5 parts by weight of aluminosilicate fiber (1-3 mm), 0.2 parts by weight of basalt fiber (3-5 mm), 2 parts by weight of oil-absorbing expanding rubber (50-100 μm), and 1 part by weight of coal tar pitch (0.5-20 μm) to obtain the intumescent pressure-bearing sealing agent; the stirring rate is 300 r / min; the stirring time is 5-10 min; and the mixing temperature is 55℃.

[0141] 2. Application method of expansion pressure sealing agent

[0142] Accurately measure 2000 mL of oil-based drilling fluid (2.0 g / cm³). 3 At 55℃, an expansion pressure-bearing sealant was added at a ratio of 21.7% (w / v). After stirring evenly, the pressure-bearing sealing capacity (pressure strength and leakage) of a 3×2mm joint plate was tested at 180℃ using a DL-3A high-temperature and high-pressure sealant evaluation instrument. See Table 2 for the results.

[0143] Example 2

[0144] 1. Preparation method of expansion pressure-bearing sealing agent

[0145] The expansion and compressive strength materials prepared in Examples 2-3 were pulverized and sieved to obtain particulate materials with a particle size of 20-40 mesh.

[0146] The expansion pressure-bearing sealant is obtained by mixing 4 parts by weight of intumescent compressive material (20-40 mesh), 4 parts by weight of irregular volcanic rock (1-2 mm), 2 parts by weight of silicon carbide (10-20 mesh), 2 parts by weight of limestone (30-50 mesh), 2 parts by weight of limestone (60-80 mesh), 2 parts by weight of limestone (100-150 mesh), 0.5 parts by weight of aluminosilicate fiber (1-3 mm), 0.2 parts by weight of basalt fiber (3-5 mm), 2 parts by weight of oil-absorbing expandable rubber (50-100 μm), and 1 part by weight of coal tar pitch (0.5-20 μm). The mixing speed is 300 r / min, the mixing time is 5-10 min, and the mixing temperature is 55℃.

[0147] 2. Application method of expansion pressure sealing agent

[0148] Accurately measure 2000 mL of oil-based drilling fluid (2.0 g / cm³). 3 At 55℃, an expansion pressure-bearing sealant was added at a ratio of 19.7% (w / v). After stirring evenly, the pressure-bearing sealing capacity (pressure strength and leakage) of a 3×2mm joint plate was tested at 180℃ using a DL-3A high-temperature and high-pressure sealant evaluation instrument. See Table 2 for the results.

[0149] Example 3

[0150] 1. Preparation method of expansion pressure-bearing sealing agent

[0151] The expansion and compressive strength material prepared in Example 3-3 was pulverized and sieved to obtain particulate materials with particle sizes of 10-20 mesh and 20-40 mesh.

[0152] The following ingredients are mixed: 2 parts by weight of intumescent pressure-resistant material (10-20 mesh), 3 parts by weight of intumescent pressure-resistant material (20-40 mesh), 6 parts by weight of irregular volcanic rock (1-2 mm), 2 parts by weight of silicon carbide (30-50 mesh), 3 parts by weight of limestone (60-80 mesh), 2 parts by weight of limestone (100-150 mesh), 0.5 parts by weight of polysilicon fiber (5-7 mm), 0.2 parts by weight of basalt fiber (3-5 mm), 0.3 parts by weight of sepiolite fiber (1-3 mm), 3 parts by weight of oil-absorbing and expanding rubber (50-100 μm), and 1 part by weight of silicone-modified acrylic resin (0.5-2 μm) to obtain the intumescent pressure-bearing sealing agent; the stirring rate is 500 r / min; the stirring time is 10-15 min; and the mixing temperature is 60℃.

[0153] 2. Application method of expansion pressure sealing agent

[0154] Accurately measure 2000 mL of oil-based drilling fluid (2.1 g / cm³). 3At 60℃, an expansion pressure-bearing sealant was added at a (w / v) ratio of 23%. After stirring evenly, the pressure-bearing sealing capacity (pressure strength and leakage) of a 4×3mm joint plate was tested at 210℃ using a DL-3A high-temperature and high-pressure sealant evaluation instrument. See Table 2 for the results.

[0155] Example 4

[0156] 1. Preparation method of expansion pressure-bearing sealing agent

[0157] The expansion and compressive strength materials prepared in Examples 1-3 were pulverized and sieved to obtain particulate materials with particle sizes of 10-20 mesh, 20-40 mesh and 100-150 mesh.

[0158] The following ingredients are mixed: 2 parts by weight of intumescent pressure-resistant material (10-20 mesh), 3 parts by weight of intumescent pressure-resistant material (20-40 mesh), 1 part by weight of intumescent pressure-resistant material (100-150 mesh), 6 parts by weight of irregular volcanic rock (1-2 mm), 2 parts by weight of silicon carbide (30-50 mesh), 3 parts by weight of limestone (60-80 mesh), 0.5 parts by weight of polysilicon fiber (5-7 mm), 0.5 parts by weight of basalt fiber (3-5 mm), 0.3 parts by weight of sepiolite fiber (1-3 mm), 4 parts by weight of oil-absorbing and expanding rubber (50-100 μm), and 1 part by weight of silicone-modified acrylic resin (0.5-2 μm) to obtain the intumescent pressure-bearing sealing agent; the stirring rate is 500 r / min; the stirring time is 10-15 min; and the mixing temperature is 60℃.

[0159] 2. Application method of expansion pressure sealing agent

[0160] Accurately measure 2000 mL of oil-based drilling fluid (2.1 g / cm³). 3 At 60℃, an expansion pressure-bearing sealant was added at a ratio of 23.3% (w / v). After stirring evenly, the pressure-bearing sealing capacity (pressure strength and leakage) of a 4×3mm joint plate was tested at 210℃ using a DL-3A high-temperature and high-pressure sealant evaluation instrument. See Table 2 for the results.

[0161] Example 5

[0162] 1. Preparation method of expansion pressure-bearing sealing agent

[0163] The expansion and compressive strength materials prepared in Examples 1-3 were pulverized and sieved to obtain particulate materials with particle sizes of 10-20 mesh and 20-40 mesh.

[0164] The following ingredients are mixed: 3 parts by weight of intumescent pressure-resistant material (10-20 mesh), 3 parts by weight of intumescent pressure-resistant material (20-40 mesh), 5 parts by weight of shaped silicon carbide (6-10 mesh), 4 parts by weight of volcanic rock (1-2 mm), 2 parts by weight of limestone (30-50 mesh), 3 parts by weight of limestone (60-80 mesh), 2 parts by weight of limestone (100-150 mesh), 0.5 parts by weight of polysilicon fiber (5-7 mm), 0.5 parts by weight of basalt fiber (3-5 mm), 0.3 parts by weight of sepiolite fiber (1-3 mm), 4 parts by weight of oil-absorbing and expanding rubber (50-100 μm), and 2 parts by weight of silicone-modified acrylic resin (0.5-2 μm). The mixing rate is 600 r / min, the mixing time is 10-15 min, and the mixing temperature is 70℃.

[0165] 2. Application method of expansion pressure sealing agent

[0166] Accurately measure 2000 mL of oil-based drilling fluid (2.2 g / cm³). 3 At 70℃, an expansion pressure-bearing sealant was added at a ratio of 29.3% (w / v). After stirring evenly, the pressure-bearing sealing capacity (pressure strength and leakage) of a 5×4mm joint plate was tested at 240℃ using a DL-3A high-temperature and high-pressure sealant evaluation instrument. See Table 2 for the results.

[0167] Example 6

[0168] 1. Preparation method of expansion pressure-bearing sealing agent

[0169] The expansion and compressive strength materials prepared in Examples 1-3 were pulverized and sieved to obtain particulate materials with particle sizes of 10-20 mesh, 20-40 mesh and 200-400 mesh;

[0170] The following ingredients are mixed: 3 parts by weight of intumescent pressure-resistant material (10-20 mesh), 3 parts by weight of intumescent pressure-resistant material (20-40 mesh), 1 part by weight of intumescent pressure-resistant material (200-400 mesh), 5 parts by weight of shaped silicon carbide (6-10 mesh), 4 parts by weight of volcanic rock (1-2 mm), 2 parts by weight of limestone (30-50 mesh), 3 parts by weight of limestone (60-80 mesh), 2 parts by weight of limestone (100-150 mesh), 0.5 parts by weight of polyimide short fiber (5-7 mm), 0.5 parts by weight of basalt fiber (3-5 mm), 0.3 parts by weight of sepiolite fiber (1-3 mm), 4 parts by weight of oil-absorbing and expanding rubber (50-100 μm), and 2 parts by weight of silicone-modified acrylic resin (0.5-2 μm). The mixing rate is 600 r / min, the mixing time is 10-15 min, and the mixing temperature is 70℃.

[0171] 2. Application method of expansion pressure sealing agent

[0172] Accurately measure 2000 mL of oil-based drilling fluid (2.2 g / cm³). 3 At 70℃, an expansion pressure-bearing sealant was added at a ratio of 30.3% (w / v). After stirring evenly, the pressure-bearing sealing capacity (pressure strength and leakage) of a 5×4mm joint plate was tested at 240℃ using a DL-3A high-temperature and high-pressure sealant evaluation instrument. See Table 2 for the results.

[0173] Example 7

[0174] 1. Preparation method of expansion pressure-bearing sealing agent

[0175] The expansion and compressive strength materials prepared in Examples 1-3 were pulverized and sieved to obtain particulate materials with particle sizes of 10-20 mesh, 20-40 mesh, 50-80 mesh and 200-400 mesh;

[0176] The following ingredients are mixed by stirring: 3 parts by weight of intumescent pressure-resistant material (10-20 mesh), 3 parts by weight of intumescent pressure-resistant material (20-40 mesh), 2 parts by weight of intumescent pressure-resistant material (50-80 mesh), 2 parts by weight of intumescent pressure-resistant material (200-400 mesh), 5 parts by weight of shaped silicon carbide (6-10 mesh), 0.5 parts by weight of polyimide short fiber (5-7 mm), 0.5 parts by weight of basalt fiber (3-5 mm), 0.3 parts by weight of sepiolite fiber (1-3 mm), 4 parts by weight of oil-absorbing and expanding rubber (50-100 μm), and 2 parts by weight of silicone-modified acrylic resin (0.5-2 μm) to obtain the intumescent pressure-bearing sealing agent; the stirring rate is 600 r / min; the stirring time is 10-15 min; and the mixing temperature is 70℃.

[0177] 2. Application method of expansion pressure sealing agent

[0178] Accurately measure 2000 mL of oil-based drilling fluid (2.2 g / cm³). 3 At 70℃, an expansion pressure-bearing sealant was added at a ratio of 22.3% (w / v). After stirring evenly, the pressure-bearing sealing capacity (pressure strength and leakage) of a 5×4mm joint plate was tested at 240℃ using a DL-3A high-temperature and high-pressure sealant evaluation instrument. See Table 2 for the results.

[0179] Example 8

[0180] The expansion pressure-bearing sealing agent was prepared according to the method described in Example 5, except that the expansion pressure-resistant material obtained in Preparation Examples 1-2 was used.

[0181] Comparative Example 1

[0182] The expansion pressure-bearing sealing agent was prepared according to the method described in Example 5, except that 3 parts by weight of thermo-sensitive shape memory polymer particles (10-20 mesh) and 3 parts by weight of thermo-sensitive shape memory polymer particles (20-40 mesh) were used instead of 3 parts by weight of expansion pressure-resistant material (10-20 mesh) and 3 parts by weight of expansion pressure-resistant material (20-40 mesh).

[0183] Comparative Example 2

[0184] The expansion pressure-bearing sealant was prepared according to the method described in Example 6, except that 5 parts by weight of shaped silicon carbide (6-10 mesh), 4 parts by weight of volcanic rock (1-2 mm), 2 parts by weight of limestone (30-50 mesh), 3 parts by weight of limestone (60-80 mesh), and 2 parts by weight of limestone (100-150 mesh) were not added.

[0185] Comparative Example 3

[0186] The expansion pressure-bearing sealant was prepared according to the method described in Example 5, except that 0.5 parts by weight of polysilicon fiber (5-7 mm), 0.5 parts by weight of basalt fiber (3-5 mm), and 0.3 parts by weight of sepiolite fiber (1-3 mm) were not added.

[0187] Comparative Example 4

[0188] The expanding pressure-bearing sealant was prepared according to the method described in Example 5, except that 4 parts by weight of oil-absorbing expanding rubber (50-100 μm) and 2 parts by weight of silicone-modified acrylic resin (0.5-2 μm) were not added.

[0189] Comparative Example 5

[0190] The expansion pressure-bearing sealing agent was prepared according to the method described in Example 5, except that the expansion pressure-resistant material obtained in Preparation Example 1-1 was used.

[0191] Test example:

[0192] 1. Compressive strength test method

[0193] The expansion and compressive strength material prepared in the preparation example was made into test samples according to a mold with specifications of 60mm×60mm×30mm. A high-temperature universal testing machine was used, with a test speed of 5mm / min and an arbitration test speed of 2mm / min. The compressive strength of the samples was tested at room temperature and above expansion temperature of 30℃. (Note: Before the high-temperature test, silicone oil was applied to the inner cavity of the test to prevent the high-temperature expansion and compressive strength material from sticking to the instrument.)

[0194] 2. Tensile strength test method

[0195] The expansion and compressive strength material prepared in the preparation example was made into test samples according to a dumbbell mold with a length of 30cm. The tensile strength of the samples was tested using a high-temperature universal testing machine at a test speed of 5mm / min and an arbitration test speed of 2mm / min, respectively, at room temperature and an expansion temperature above 30℃.

[0196] Using the test method of the present invention described above, the compressive strength and tensile strength of preparation examples 1 to 3 were tested, and the test results are shown in Table 1 below.

[0197] Table 1. Expansion temperature and mechanical property tests of preparation examples 1-3

[0198]

[0199]

[0200] As shown in Table 1, the mechanical strength (including compressive and tensile strength) loss at 190℃ in Preparation Examples 1-3 was relatively small. The compressive strength retention rate was all above 25%, and the tensile strength retention rate was all above 20%. Furthermore, the mechanical strength retention rates of Preparation Examples 1-3, 2-3, and 3-3 under high pressure in steps S3 and S4 were higher than those of other preparation examples in the same group.

[0201] 3. High-Temperature Pressure Leakage Prevention and Sealing Performance Test Method

[0202] A DL-3A high-temperature and high-pressure plugging test apparatus (working pressure 40 MPa, temperature 180-240℃) was used to simulate downhole high-temperature and high-pressure conditions to evaluate the pressure-bearing capacity of the plugging material for sealing fractures. Using sealing plates with different fracture widths, the pressure-bearing capacity of the plugging fluid at different temperatures was tested. In Examples 1 and 2, the high-temperature and high-pressure plugging tests involved heating to a predetermined temperature of 180℃, holding at that temperature for 2.9 hours, and then pressurizing. In Examples 3 and 4, the high-temperature and high-pressure plugging tests involved heating to a predetermined temperature of 210℃, holding at that temperature for 1.7 hours, and then pressurizing. In Examples 5 to 8 and Comparative Examples 1 to 5, the high-temperature and high-pressure plugging tests involved heating to a predetermined temperature of 240℃, holding at that temperature for 0.4 hours, and then pressurizing. The test results are shown in the table below.

[0203] The high-temperature pressure-resistant leak-proofing performance of the sealing agents prepared in Examples 1-8 and Comparative Examples 1-5 was tested, and the test results are shown in the table below.

[0204] Table 2 Test performance of the plugging agents prepared in Examples 1-8 and Comparative Examples 1-5

[0205] Test case Test temperature / ℃ seam width / mm Compressive strength / MPa Leakage / mL Example 1 180 3×2 18.7 26 Example 2 180 3×2 21.5 30 Example 3 210 4×3 27.9 36 Example 4 210 4×3 30.5 35 Example 5 240 5×4 32.6 29 Example 6 240 5×4 ＞40 11 Example 7 240 5×4 31.9 7 Example 8 240 5×4 21.7 79 Comparative Example 1 240 5×4 12.5 234 Comparative Example 2 240 5×4 1.2 572 Comparative Example 3 240 5×4 29.4 116 Comparative Example 4 240 5×4 17 289 Comparative Example 5 240 5×4 9.4 253

[0206] As shown in Table 2, the plugging agents prepared in Examples 1-8 exhibit good pressure-bearing sealing capabilities for cracks approximately 5 mm in diameter. This is mainly manifested in high pressure-bearing strength, even exceeding 40 MPa, and low leakage. Compared to Example 5, Comparative Example 1, using the same size and quantity of temperature-sensitive shape memory polymer particles instead of the expanding pressure-resistant material, resulted in a plugging agent that did not undergo steam-driven expansion, exhibiting low pressure-bearing strength and high leakage. Compared to Example 6, Comparative Example 2, without the addition of oleophilic rigid particulate material, failed to provide high pressure-bearing capacity, exhibiting extremely low pressure-bearing strength and extremely high leakage. Compared to Example 5, Comparative Example 3, without the addition of microporous fibers, resulted in a decrease in the retention capacity of the plugging agent upon reaching the lost formation, leading to a larger leakage. The absence of a microporous fiber network structure slightly reduced pressure-bearing strength and increased leakage rate. Compared to Example 5, Comparative Example 4, without the addition of oil-absorbing flexible plugging material, resulted in decreased sealing layer density, leading to decreased pressure-bearing strength and a corresponding increase in leakage rate. Compared with Example 5, Comparative Example 5 has a lower expansion temperature, and the material expands and bridges before reaching the bottom of the well, resulting in a sealing effect and reducing instantaneous leakage. However, the bridging is unstable during gradual pressure bearing, leading to a decrease in pressure bearing and an increase in leakage.

[0207] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. An expansion-pressure sealing agent, characterized in that, The expansion pressure-bearing sealing agent, in 100 wt% form, comprises 10-48 wt% expansion pressure-resistant material, 20-65 wt% oleophilic rigid particulate material, 0.1-10 wt% microporous fiber, and 0.5-30 wt% oil-absorbing flexible sealing material. The expansion and pressure-resistant material comprises a porous structure formed by curing a thermosetting resin and water sealed in the porous structure; the pore size of the porous structure is 150μm to 300μm, and the porosity of the expansion and pressure-resistant material is 8 to 25%. DSC measurements showed that the expandable compressive-resistant material had a first weight loss peak in the range of 100℃ to 300℃, a second weight loss peak in the range of 350℃ to 380℃, and a third weight loss peak in the range of 400℃ to 500℃; the weight loss rate of the expandable compressive-resistant material at the first weight loss peak was <2.0%, the weight loss rate at the second weight loss peak was 2% to 32%, and the weight loss rate at the third weight loss peak was 33% to 61%. The method for preparing the expansion-resistant compressive material includes the following steps: Preparation of the first mixture S1: The thermosetting resin is mixed with the first curing agent to obtain the first mixture; Preparation of the second mixture S2: Mix the second curing agent with water to obtain the second mixture; Preparation of the third mixture S3: Mix the first mixture and the second mixture evenly, add the accelerator and foaming agent, and stir for ≥10 minutes at 60℃~85℃ and 0.3~3MPa with the speed adjusted to 700rpm~3000rpm to obtain the third mixture; S4 curing: The third mixture is cured at 0.3 to 3 MPa to obtain the expansion and pressure-resistant material.

2. The expanding pressure-bearing leak-sealing agent according to claim 1, characterized in that, The expansion pressure-bearing sealing agent, in 100 wt% form, comprises 20-35 wt% expansion pressure-resistant material, 40-60 wt% oleophilic rigid particulate material, 0.1-8 wt% microporous fiber, and 1-25 wt% oil-absorbing flexible sealing material. And / or, the thermosetting resin comprises one or more of epoxy resin, phenolic resin, polyetherketone resin, and polyimide resin; And / or, the pore size of the porous structure is 200μm to 280μm, and the porosity of the expansion and compressive strength material is 10% to 20%.

3. The expanding pressure-bearing leak-sealing agent according to claim 1 or 2, characterized in that, In step S1, the thermosetting resin is heated to 60°C to 85°C, the first curing agent is added, the temperature is adjusted to 5°C to 30°C above the melting point of the first curing agent, and after the first curing agent is completely dissolved, it is stirred at a stirring speed of 200 to 400 rpm for 20 to 60 minutes, and then adjusted to 60°C to 85°C to obtain the first mixture. And / or, step S2 includes step S2-1, step S2-2, or step S2-3; Step S2-1: The second curing agent is a solid with a melting point ≥90℃. Add the second curing agent to the solution and adjust the temperature to 5℃~30℃ above the melting point of the second curing agent. After the second curing agent is completely dissolved, adjust the temperature to 60℃~85℃, add water, and stir at a stirring speed of 200~400rpm for 20~60min to obtain the second mixture. Step S2-2: The second curing agent is a solid with a melting point <90℃. Add the second curing agent to water and heat it to 5℃~10℃ above the melting point of the second curing agent. After the second curing agent is completely dissolved, adjust the temperature to 60℃~85℃ and stir at a stirring speed of 200~400rpm for 20~60min to obtain the second mixture. Step S2-3: The second curing agent is a liquid. Adjust the temperature to 60℃~85℃, add water to the second curing agent, and stir at a stirring speed of 200~400rpm for 20~60min to obtain the second mixture. And / or, in step S3, nitrogen gas is introduced to pressurize the mixture, the second mixture is added to the first mixture, an accelerator and a foaming agent are added, and the mixture is stirred for 10-30 minutes to obtain a third mixture; And / or, in step S4, the pressure curing includes two or three of the following: first curing, second curing, and third curing; the first curing is carried out at a constant temperature of 100℃~110℃ for 2h~8h; the second curing is carried out at a constant temperature of 120℃~130℃ for 0.5h~4h; and the third curing is carried out at a constant temperature of 140℃~160℃ for 0.5h~4h. And / or, the first curing agent and the second curing agent may be the same or different, and each is independently selected from one or more of acid anhydride curing agents, phenolic curing agents, and aromatic polyamine curing agents; And / or, the mass ratio of the first curing agent to the second curing agent is (0.60~3):

1.

4. The expandable pressure-bearing sealant according to any one of claims 1-3, characterized in that, Based on 100 parts by weight of thermosetting resin, the total amount of the first curing agent and the second curing agent is 50 to 100 parts by weight, the amount of accelerator is 0 to 2 parts by weight, the amount of water is 10 to 50 parts by weight, and the amount of foaming agent is 0.1 to 3 parts by weight.

5. The expanding pressure-bearing leak-sealing agent according to claim 4, characterized in that, The amount of the solution used is 10 to 20 parts by weight; and / or, the solution contains at least one of liquid resin curing agent and liquid resin toughening agent; preferably, the solution contains at least one of modified aromatic amine liquid curing agent, modified phenolic high-temperature curing agent and alkenyl succinic anhydride. And / or, the epoxy resin comprises one or more of glycidyl ether epoxy resin, glycidyl amine epoxy resin, glycidyl ester epoxy resin, imide modified epoxy resin, and phenolic modified epoxy resin. Preferably, the epoxy resin comprises one or more of bisphenol A diglycidyl ether, phenolic epoxy resin, and imide epoxy resin; And / or, the anhydride curing agent comprises one or more of maleic anhydride, alkenyl succinic anhydride, phthalic anhydride, cyclopentadienoic dianhydride, and methyl hexahydrophthalic anhydride; And / or, the accelerator comprises one or more of triethanolamine, dimethylaniline, and 2,4,6-tris(dimethylaminomethyl)phenol; And / or, the water is fresh water or salt water, preferably, the water contains a foam enhancer; More preferably, the foam enhancer comprises one or both of a surfactant or a thickening and shearing agent; the mass content of the foam enhancer is 0.1% to 1% based on the weight of the water; Most preferably, the surfactant-based foam enhancer comprises one or more of polysorbate, sorbitan monooleate, oleyl alcohol polyoxyethylene ether, and dodecyl oleate; And / or, the thickening and cutting agent-type foam reinforcing agent comprises one or more of hydroxyethyl methyl cellulose, polyacrylamide, and sodium carboxymethyl starch; And / or, the foaming agent comprises one or more of anionic foaming agents, cationic foaming agents, and nonionic foaming agents; Preferably, the foaming agent is an anionic foaming agent, and preferably includes one or more of sodium dodecylbenzene sulfonate, fatty alcohol glyceryl ether sulfonate, or α-olefin sulfonate.

6. The expanding pressure-bearing sealant according to any one of claims 1-5, characterized in that, The oleophilic rigid particulate material is selected from at least one of geological-based polymers and modified minerals; Preferably, the oleophilic rigid particulate material is selected from at least one of limestone, quartz sand, volcanic rock, and silicon carbide; And / or, the oleophilic rigid particulate material is composed of irregularly shaped rigid particles and spherical rigid particles, wherein the mass ratio of the irregularly shaped rigid particles to the spherical rigid particles is 1:(1-4); And / or, the particle size of the oleophilic rigid particulate material is selected from at least three gradations selected from 1-2 mm, 3-5 mm, 6-10 mesh, 10-20 mesh, 30-50 mesh, 60-80 mesh, 100-150 mesh, 200-400 mesh, and 400-800 mesh.

7. The expandable pressure-bearing sealant according to any one of claims 1-6, characterized in that, The microporous fiber is selected from at least one of microporous oil-absorbing plant fiber, mineral fiber, and polyester fiber; Preferably, the microporous fiber is selected from at least one of aluminosilicate fiber, polysilicon fiber, sepiolite fiber, basalt fiber, ceramic fiber, polyvinyl alcohol fiber, and polyimide fiber; And / or, the pore size of the microporous fiber is 0.1 mm to 0.5 mm, and the fiber length is selected from at least one of 1 to 3 mm, 3 to 5 mm, 5 to 7 mm, 7 to 10 mm, and 12 to 15 mm.

8. The expandable pressure-bearing sealant according to any one of claims 1-7, characterized in that, The oil-absorbing flexible plugging material is selected from at least one of oleophilic plugging materials, oil-soluble plugging materials, or high-temperature melt coating materials; Preferably, the oil-absorbing flexible sealing material is selected from at least one of oil-absorbing expanding rubber, oil-absorbing expanding resin, silicone-modified acrylate, and coal tar pitch; And / or, the expansion ratio of the oil-absorbing flexible sealing material is 0.5 to 1.5; And / or, the oil-absorbing flexible sealing material is made of micron-sized particles with a particle size range of 0.5 to 200 μm.

9. The method for preparing the expansion pressure-bearing sealing agent according to any one of claims 1-8, characterized in that, Includes the following steps: The expansion pressure-resistant material, the oleophilic rigid particulate material, the microporous fiber, and the oil-absorbing flexible sealing material are mixed together to obtain the expansion pressure-bearing leak-sealing agent. Preferably, the stirring rate is 300-1000 r / min; the stirring time is 5-20 min; and the mixing temperature is 50-90℃.

10. A method for sealing leaks using the expandable pressure-bearing leak-sealing agent according to any one of claims 1-8 or the expandable pressure-bearing leak-sealing agent prepared by the preparation method according to claim 9, characterized in that, Includes the following steps: In oil-based sealing, the sealing agent is added to a container with a temperature of 100-260℃ and a density of 1.5-2.4 g / cm³. 3 In the drilling fluid, the amount of the plugging agent is 10% to 50% (w / v).

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