Oil-gas well cement sheath microcrack repairing gel and preparation method thereof

Abstract

The invention provides an oil-gas well cement sheath microcrack repairing gel and a preparation method thereof. The repairing gel comprises the following components in parts by weight: 65-85 parts of glycidyl amine epoxy resin; 10 to 25 parts by weight of toluene glycidyl ether; 0.1 to 1.5 parts by weight of vinyl triisopropenyloxy silane; and 5-10 parts by weight of a curing agent. The preparation method comprises the following steps: step 1, mixing and stirring glycidyl amine epoxy resin and toluene glycidyl ether; step 2, mixing the mixture obtained in the step 1 with vinyltriisopropenyloxysilane, and stirring to obtain a resin mixture; 3, the resin mixture and a curing agent are subjected to a curing reaction, and the oil and gas well cement sheath microcrack repairing gel is obtained. The repairing gel system disclosed by the invention has relatively low viscosity, is suitable for a shaft temperature of 150-200 DEG C, can be used for effectively repairing micro-cracks in an oil-gas well cement sheath after being cured, has high bonding strength, does not have the problem of curing body softening, and can resist long-term corrosion of acid gas at the same time.

Description

Technical Field

[0001] This invention relates to the field of repairing microfractures in the annulus of oil and gas wells, and particularly to a gel for repairing microfractures in the cement annulus of oil and gas wells and its preparation method. Background Technology

[0002] In oil and gas well development, the integrity of the cement sheath is crucial to the safety and stability of the wellbore. Especially for thermal recovery wells or high-temperature wells, micro-cracks often appear in the cement sheath due to multiple factors, including changes in the physical properties of various thermal fluids during extraction, friction effects, gravity effects, and endothermic and exothermic effects caused by phase changes in the thermal fluids. These micro-cracks can not only lead to formation fluid intrusion into the wellbore but also cause serious problems such as oil and gas leaks and wellbore instability, posing significant challenges to the safe production and economic benefits of oil and gas wells.

[0003] Currently, the main repair technologies for micro-fractures in oil and gas well cement sheaths include cement extrusion, cement stone self-repair (adding self-repairing materials to cement slurry), and subsequent filling of micro-fractures with chemical materials. From practical field experience, cement extrusion repair has minimal effect. While cement stone self-repair only requires adding self-repairing materials to cement slurry and is simple to operate, its repair efficiency is low and it is difficult to completely fill micro-fractures. Subsequent filling of micro-fractures mainly uses chemical plugging agents. By injecting chemical plugging agents, the bonding effect between the agent and the micro-fractures is used to achieve sealing. As long as the repair material can be well injected into the micro-fractures, the repair effect is relatively good.

[0004] Chinese patent CN110229651A provides a resin plugging agent for repairing cement annular cracks. It is mainly used for cracks, pores, microcracks inside cement stone, and micro-annular gaps at the cementing interface in the cement annulus connected to the wellhead. However, the operating temperature of this plugging agent is between 35℃ and 60℃, and the highest compressive strength of the cured body is 23MPa. The operating temperature range of this plugging agent is relatively low, and it is mainly used at the wellhead.

[0005] Chinese patent CN116462798A discloses a nanocomposite hydrogel for repairing microcracks in cement sheaths. This hydrogel mainly utilizes nanomaterials, anionic monomers, functional monomers that generate anions after hydrolysis, and cationic groups generated by hydrolysis in the presence of acidic gases to prepare a nanocomposite hydrogel for cement sheath repair. The nanocomposite hydrogel is then added to cement slurry to prepare self-healing cement. However, this plugging agent is mainly used in CCUS wells, and it can only be effective when leaked acidic gases activate the plugging agent after microcracks are generated in the cement sheath.

[0006] Chinese patent CN103468231A discloses a silane coupling agent-coated self-healing agent for cement sheaths. This agent coats active minerals with a silane coupling agent, forming a waterproof protective film on the surface of the active minerals. This makes the activity of the active minerals latent, not participating in the hydration reaction within the cementing slurry system. The hydration reaction only begins when the surface film is damaged by the cement sheath, forming hydration products that automatically repair the damaged areas of the cement sheath. However, the self-healing material has extremely low efficiency, requiring both activation conditions and low self-healing efficiency. Existing chemical plugging technologies often exhibit decreased mechanical properties at high temperatures. To achieve better performance, the amount of functional material needs to be increased, leading to increased initial viscosity and difficulty in injection into microcracks. Therefore, these technologies struggle to meet the requirements for on-site construction and long-term effective sealing of microcracks in cement sheaths.

[0007] CN 113930200 A discloses a sealant for treating annular pressure and its preparation method. The sealant comprises a composite resin, a curing agent, a toughening agent, and a viscosity reducer. This sealant is extruded from the surface annulus into the annulus of an oil and gas well and cured to seal micro-cracks in the cement sheath, effectively sealing the annulus of the oil and gas well to solve the problem of casing annular pressure. However, the viscosity range of this sealant is 60–2500 mPa·s, and its application temperature is 20–50℃, indicating poor temperature resistance.

[0008] CN 112341999 A discloses an epoxy resin cementing and plugging system, its preparation method, and its application. The plugging system comprises epoxy resin (bisphenol A type), a curing agent (preferably 90% polyetheramine and 10% diethylenetriamine), and a diluent selected from ethyl acetate and butyl acetate. This resin plugging system features adjustable setting time, adjustable system density, high compressive strength, and good flexibility, making it suitable for managing wells in annular pressure zones and effectively solving problems such as cross-contamination between downhole oil, water, and gas layers. However, the density regulator in this system is a solid phase, and the application temperature is limited to 20–120℃, restricting its application range.

[0009] Therefore, further research is needed in this field on microcrack repair agents for cement sheaths in oil and gas wells. Summary of the Invention

[0010] The main objective of this invention is to provide a microcrack repair gel for oil and gas well cement sheaths and its preparation method, so as to overcome the defects of existing microcrack repair agents for oil and gas well cement sheaths, such as low compressive strength, poor temperature resistance, excessively high viscosity, or weak bonding strength.

[0011] To achieve the above objectives, the present invention provides a microcrack repair gel for oil and gas well cement sheaths, comprising:

[0012] 65-85 parts by weight of glycidyl amine epoxy resin;

[0013] 10-25 parts by weight of toluene glycidyl ether;

[0014] Vinyltriisopropoxysilane 0.1 to 1.5 parts by weight;

[0015] 5-10 parts by weight of curing agent.

[0016] The microcrack repair gel for cement sheaths in oil and gas wells described in this invention comprises, wherein the glycidylamine epoxy resin is N,N-bis(glycidyl)aniline; and the toluene glycidyl ether is 2-toluene glycidyl ether.

[0017] The microcrack repair gel for cement sheaths in oil and gas wells described in this invention, wherein the curing agent is one or more of tetrahydrophthalic anhydride, diethylformamide, melamine, and diethyltoluenediamine.

[0018] The microcrack repair gel for cement sheaths in oil and gas wells described in this invention further includes 0.5 to 2.0 parts by weight of defoamer.

[0019] The microcrack repair gel for cement sheaths in oil and gas wells described in this invention, wherein the defoamer is a polyether-modified silicone oil defoamer or a GPE-type polyoxyethylene ether.

[0020] The microcrack repair gel for oil and gas well cement sheaths according to the present invention comprises:

[0021] 75-85 parts by weight of glycidyl amine epoxy resin;

[0022] 10-18 parts by weight of toluene glycidyl ether;

[0023] Vinyltriisopropoxysilane 0.1 to 1 part by weight;

[0024] 6-10 parts by weight of curing agent.

[0025] To achieve the above objectives, the present invention also provides a method for preparing the above-mentioned microcrack repair gel for oil and gas well cement sheaths, characterized by comprising the following steps:

[0026] Step 1: Mix glycidyl amine epoxy resin and toluene glycidyl ether, and stir.

[0027] Step 2: Mix the mixture obtained in Step 1 with vinyltriisopropoxysilane and stir to obtain a resin mixture;

[0028] Step 3: The resin mixture is subjected to a curing reaction with a curing agent to obtain a microcrack repair gel for oil and gas well cement sheaths.

[0029] The preparation method of the microcrack repair gel for oil and gas well cement sheaths according to the present invention includes the addition of an antifoaming agent in step 3 of the curing reaction.

[0030] The preparation method of the microcrack repair gel for oil and gas well cement sheaths according to the present invention includes a stirring speed of 1400 r / min-1600 r / min in step 1 and a stirring speed of 800 r / min-1200 r / min in step 2.

[0031] The preparation method of the microcrack repair gel for oil and gas well cement sheaths according to the present invention includes the following steps: the curing reaction temperature in step 3 is 10-20℃, the curing reaction time is 8-12 min, and the stirring is carried out at 400 r / min-600 r / min during the curing reaction.

[0032] The beneficial effects of this invention are:

[0033] This invention utilizes specific epoxy resin, diluent, and coupling agent in a synergistic manner to prepare a microcrack repair gel for oil and gas well cement sheaths, which has the following characteristics:

[0034] (1) The microcrack repair gel of the cement sheath in oil and gas wells of the present invention has no solid phase components, which is conducive to injection into the microcracks of the cement sheath. It will not be filtered out due to the presence of solid phase particles, thus preventing it from entering the microcracks.

[0035] (2) The repair gel system of the present invention has a low viscosity, not higher than 38 mPa·s, which can be freely adjusted according to the construction conditions and the size of the microcracks in the annular cement ring. The low viscosity can reduce the annular pumping pressure, which is beneficial to construction.

[0036] (3) The repair gel system of the present invention is suitable for wellbore temperatures of 150℃~200℃. After curing, it effectively repairs microcracks in the cement sheath of oil and gas wells. It has high bonding strength and will not cause softening of the cured body. At the same time, it can resist long-term corrosion by acidic gases. Attached Figure Description

[0037] Figure 1 This is a state diagram of the cured body prepared in Example 1 of the present invention;

[0038] Figure 2 This is a state diagram of the cured body prepared in Comparative Example 1 of the present invention;

[0039] Figure 3 This is a state diagram of the cured body prepared in Comparative Example 2 of the present invention;

[0040] Figure 4 This is a state diagram of the cured body prepared in Comparative Example 3 of the present invention. Detailed Implementation

[0041] The technical solution of the present invention will be described in detail below. The following embodiments are implemented under the premise of the technical solution of the present invention and a detailed implementation process is given. However, the protection scope of the present invention is not limited to the following embodiments. Structures or experimental methods that do not specify specific conditions in the following embodiments are generally performed under conventional conditions.

[0042] This invention provides a gel for repairing microcracks in the cement sheath of oil and gas wells, comprising:

[0043] 65-85 parts by weight of glycidyl amine epoxy resin;

[0044] 10-25 parts by weight of toluene glycidyl ether;

[0045] Vinyltriisopropoxysilane 0.1 to 1.5 parts by weight;

[0046] 5-10 parts by weight of curing agent.

[0047] This invention uses a specific glycidylamine epoxy resin, toluene glycidyl ether diluent, and vinyltriisopropoxysilane coupling agent to prepare a repair gel. The epoxy resin in the solid-free gel is a hyperbranched, near-spherical polymer with low viscosity, high solubility, and multiple functional groups. The outer layer contains a large number of terminal epoxy groups, and the inner layer is a repeating unit structure containing polysiloxane and epoxy groups. It has good compatibility with the epoxy resin matrix and contains a large number of nanoscale cavities. At the same time, the molecular chain entanglement of this hyperbranched polymer is low. For the same relative molecular mass, the viscosity of the hyperbranched polymer in solution is lower. In addition, the introduction of Si-O-Si flexible segments into the epoxy resin effectively improves the toughness after curing. Therefore, the gel obtained by this invention through the synergistic effect of specific resins, diluents and coupling agents has high temperature resistance, low viscosity, and is easy to inject. After curing, it can maintain stable physicochemical properties in high temperature environments, effectively repair microcracks in cement sheaths in high-temperature wells, improve the sealing and stability of the wellbore, reduce the risk of oil and gas leakage, and is of great significance for ensuring the safe and efficient production of oil and gas wells.

[0048] Among them, toluene glycidyl ether is a high-temperature active diluent that introduces polyether chain segments and other groups with slightly stronger polarity, which makes the physical interaction between polymer molecules stronger during the resin dilution process, thus improving the dilution performance. In addition, this type of diluent also has good compatibility with epoxy resins, ensuring good stability of the solid-phase gel-free system at high temperatures.

[0049] Furthermore, the vinyltriisopropoxysilane coupling agent (550 silane coupling agent) of this invention can improve the structural stability, compatibility, thermal stability, and weather resistance of solid-state gels and formations or cement rings. The molecular structure of vinyltriisopropoxysilane contains a vinyl functional group with an unsaturated double bond and three hydrolyzable isopropoxy groups. Because the isopropoxy groups and vinyl groups can hydrolyze under acidic or alkaline conditions, they generate reactive silanol groups. Through cross-linking to form silicon-oxygen bonds, the material exhibits high stability in chemically corrosive environments. Vinyltriisopropene can effectively increase the compatibility between inorganic materials (such as formations, casings, etc.) and organic matrices. By forming covalent or hydrogen bonds, it significantly improves the water resistance and adhesion of the substrate, thereby enhancing compatibility. In addition, its long Si-O bonds endow vinyltriisopropoxysilane with good thermal stability and maintain excellent mechanical and physical properties over a wide temperature range, exhibiting good weather resistance.

[0050] In one embodiment, the microcrack repair gel for oil and gas well cement sheaths of the present invention comprises:

[0051] 75-85 parts by weight of glycidyl amine epoxy resin;

[0052] 10-18 parts by weight of toluene glycidyl ether;

[0053] Vinyltriisopropoxysilane 0.1 to 1 part by weight;

[0054] 6-10 parts by weight of curing agent.

[0055] In one embodiment, the glycidylamine epoxy resin is a diglycidyl aromatic amine, more specifically, for example, N,N-bis(glycidyl)aniline (MF2133 special epoxy resin). In another embodiment, the amount of glycidylamine epoxy resin added is 75 to 85 parts by weight, for example, 77 parts by weight, 79 parts by weight, 81 parts by weight, or 83 parts by weight.

[0056] In one embodiment, the toluene glycidyl ether is, for example, 2-toluene glycidyl ether (Heloxy_Modifier62 epoxy resin reactive diluent). The amount of toluene glycidyl ether added is 10 to 18 parts by weight, for example, 11.8 parts by weight, 14 parts by weight, 16 parts by weight, or 18 parts by weight.

[0057] In one embodiment, the amount of vinyltriisopropoxysilane added is 0.1 to 1 part by weight, for example, 0.3 parts by weight, 0.5 parts by weight, 0.7 parts by weight, or 0.9 parts by weight.

[0058] This invention does not impose any particular limitation on the curing agent, but the curing agent should have good acid resistance and be able to cure at high temperatures. The curing agent is preferably one or more of tetrahydrophthalic anhydride, diethylformamide, melamine, and diethyltoluenediamine. In one embodiment, the amount of curing agent added is 5 to 10 parts by weight, for example, 6 parts by weight, 8.2 parts by weight, or 9 parts by weight.

[0059] In one embodiment, the microcrack repair gel for oil and gas well cement sheaths of the present invention further includes an antifoaming agent, wherein the amount of antifoaming agent added is 0.5 to 2.0 parts by weight, for example, 0.7 parts by weight, 1.0 parts by weight, 1.5 parts by weight, or 1.8 parts by weight. In another embodiment, the antifoaming agent of the present invention is a polyether-modified silicone oil antifoaming agent or a GPE type polyoxyethylene ether.

[0060] This invention also provides a method for preparing the above-mentioned microcrack repair gel for oil and gas well cement sheaths, comprising the following steps:

[0061] Step 1: Mix glycidyl amine epoxy resin and toluene glycidyl ether, and stir.

[0062] Step 2: Mix the mixture obtained in Step 1 with vinyltriisopropoxysilane and stir to obtain a resin mixture;

[0063] Step 3: The resin mixture is subjected to a curing reaction with a curing agent to obtain a microcrack repair gel for oil and gas well cement sheaths.

[0064] In detail, glycidyl amine epoxy resin and toluene glycidyl ether are mixed and stirred at 10-20°C, with a stirring speed of, for example, 1400-1600 r / min, more specifically 1500 r / min, and a stirring time of, for example, 30 min.

[0065] Then, the mixture of glycidyl amine epoxy resin and toluene glycidyl ether is mixed with vinyltriisopropoxysilane at a mixing temperature of, for example, 10-20°C, and stirred at a stirring speed of, for example, 800-1200 r / min, more preferably 1000 r / min, for 10 min to obtain a resin mixture.

[0066] Next, the resin mixture is mixed with a curing agent to carry out a curing reaction. In one embodiment, an antifoaming agent may also be added to the mixture for defoaming treatment during the curing process. In another embodiment, the curing temperature is 10–20°C, the curing time is 8–12 min, and the mixture is stirred at 400–600 rpm, for example, 500 rpm, for a duration of 10 min.

[0067] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0068] Raw material source:

[0069] MF2133 Special Epoxy Resin, Hubei Zhenzhengfeng New Materials Co., Ltd.;

[0070] Epoxy resin reactive diluent, Henson & Co., Inc., USA;

[0071] Phenolic resin, Shandong Huihuang Chemical Co., Ltd.;

[0072] Polyethylene resin, Hebei Judi Energy Saving Technology Co., Ltd.;

[0073] Haiyin Epoxy Resin, Hubei Xitai Chemical Co., Ltd.;

[0074] Bismaleimide, N-phenylmaleimide, Hubei Maidehao Chemical Co., Ltd.;

[0075] Maleic anhydride, Zhongshan Dixing Chemical Co., Ltd.;

[0076] Fluorine-containing reactive diluent, Hubei Green Home Materials Technology Co., Ltd.;

[0077] Tetrahydrophthalic anhydride, Hubei Maidehao Chemical Co., Ltd.;

[0078] Diethylformamide, Shandong Yushuo Chemical Co., Ltd.;

[0079] Melamine, Hubei Dongcao Chemical Technology Co., Ltd.;

[0080] Diethyltoluenediamine, Jiangsu Shuangyang Chemical Co., Ltd.;

[0081] 550 silane coupling agent, Hubei Jianghan Fine Chemical Co., Ltd.;

[0082] Evaluation and analysis methods:

[0083] The Brookfield viscosity of the liquid phase gel before curing in the examples and comparative examples was measured according to GB / T11145; the compressive strength and thickening time were measured according to the rheological test content of GB / T-19139-2012.

[0084] The permeability of the solidified bodies in the examples and comparative examples was determined according to SY / T5336-2006. The acid and alkali resistance test of the solidified bodies involved preparing core samples of the gel solidified body with a diameter of approximately 25.4 mm × height of 46.0 mm. These core samples were then placed in 10% HCl solution and 1% NaOH solution, respectively, and the mass of the core samples was measured at different times to determine the acid and alkali resistance of the solidified bodies. The bonding strength test of the solidified bodies used a self-designed bonding strength mold with an inner diameter of 50 mm, an outer diameter of 100 mm, and a height of 100 mm, made of N80 steel similar in quality to the casing steel. After the solid-free gel solidified inside the mold, a bonding strength specimen was formed. A uniform load was applied, and the ultimate shear compression load was obtained when the solid-free gel was extruded from the mold. Two solid-free gel specimens were tested in each group, and the bonding strength of the solid-free gel was calculated based on the experimental results.

[0085]

[0086] In the formula: F b — Bond strength, MPa; P b —Tension limit load, N; d—Die inner diameter, mm; h—Die height, mm.

[0087] Solid-phase gel thickening test conditions: 21MPa×150℃; compressive strength test conditions: 24h×200℃, while observing the external morphology of the cured module; bonding strength test conditions: cured body sample cured at 200℃ for 3d.

[0088] Example 1

[0089] The high-temperature resistant, low-viscosity, solid-free gel for repairing microcracks in oil and gas well cement sheaths is prepared from the following raw materials: 79 parts by weight of MF2133 special epoxy resin, 11.8 parts by weight of Heloxy_Modifier62 epoxy resin reactive diluent, 0.3 parts by weight of 550 silane coupling agent, 8.2 parts by weight of diethyltoluene diamine, and 0.7 parts by weight of polyether modified silicone oil.

[0090] The preparation method includes the following steps:

[0091] a1) Mix MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent to obtain diluted special epoxy resin; stir at 1400 r / min for 30 min at 15℃.

[0092] a2) Mix the MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent mixture obtained in a1 with 550 silane coupling agent to obtain a special resin mixture; stir uniformly at 1200 r / min for 10 min at 20℃.

[0093] a3) Mix the MF2133 special epoxy resin, Heloxy_Modifier62 epoxy resin reactive diluent, and 550 silane coupling agent mixture from a2 with diethyltoluene diamine and carry out a curing reaction. At the same time, mix with polyether modified silicone oil defoamer for defoaming treatment. The curing reaction can be carried out at 20°C by uniformly stirring at 400r / min for 10min.

[0094] Example 2

[0095] The high-temperature resistant, low-viscosity, solid-free gel for repairing microcracks in oil and gas well cement sheaths is prepared from raw materials including the following components: 79 parts by weight of MF2133 special epoxy resin, 12.98 parts by weight of Heloxy_Modifier62 epoxy resin reactive diluent, 0.32 parts by weight of 550 silane coupling agent, 7 parts by weight of diethyltoluene diamine curing agent, and 0.7 parts by weight of polyether modified silicone oil.

[0096] The preparation method includes the following steps:

[0097] a5) Mix MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent to obtain diluted special epoxy resin; stir at 1500 r / min for 30 min at 10℃.

[0098] a6) The MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent mixture obtained in a5 are mixed with 550 silane coupling agent to obtain a special resin mixture; and stirred uniformly at 1000r / min for 10min at 10℃.

[0099] a7) Mix the MF2133 special epoxy resin, Heloxy_Modifier62 epoxy resin reactive diluent, and 550 silane coupling agent mixture from a6 with diethyltoluene diamine and carry out a curing reaction. At the same time, mix with polyether modified silicone oil defoamer for defoaming treatment. The curing reaction can be carried out at 15°C by uniformly stirring at 600r / min for 10min.

[0100] Example 3

[0101] The high-temperature resistant, low-viscosity, solid-free gel for repairing microcracks in oil and gas well cement sheaths is prepared from raw materials including the following components: 81 parts by weight of MF2133 special epoxy resin, 11.8 parts by weight of Heloxy_Modifier62 epoxy resin reactive diluent, 0.3 parts by weight of 550 silane coupling agent, 6.2 parts by weight of diethyltoluene diamine curing agent, and 0.7 parts by weight of polyether modified silicone oil.

[0102] The preparation method includes the following steps:

[0103] a9) Mix MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent to obtain diluted special epoxy resin; stir at 1500 r / min for 30 min at 20℃.

[0104] a10) The MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent mixture obtained in a9 are mixed with 550 silane coupling agent to obtain a special resin mixture; the mixture is stirred uniformly at 1000 r / min for 10 min at 15°C.

[0105] a11) Mix the MF2133 special epoxy resin, Heloxy_Modifier62 epoxy resin reactive diluent, and 550 silane coupling agent mixture from a10 with diethyltoluene diamine and carry out a curing reaction. At the same time, mix with polyether modified silicone oil defoamer for defoaming treatment. The curing reaction can be carried out at 10°C by uniformly stirring at 500 r / min for 8 min.

[0106] Example 4

[0107] The high-temperature resistant, low-viscosity, solid-free gel for repairing microcracks in oil and gas well cement sheaths is prepared from raw materials including the following components: 79 parts by weight of MF2133 special epoxy resin, 12.98 parts by weight of Heloxy_Modifier62 epoxy resin reactive diluent, 0.2 parts by weight of 550 silane coupling agent, 7 parts by weight of diethyltoluene diamine curing agent, and 0.82 parts by weight of polyether modified silicone oil.

[0108] The preparation method includes the following steps:

[0109] a13) Mix MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent to obtain diluted special epoxy resin; stir at 1500 r / min for 30 min at 18℃.

[0110] a14) The MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent mixture obtained in a13 are mixed with 550 silane coupling agent to obtain a special resin mixture; and stirred uniformly at 1000r / min for 10min at 20℃.

[0111] a15) Mix the MF2133 special epoxy resin, Heloxy_Modifier62 epoxy resin reactive diluent, and 550 silane coupling agent mixture from a14 with diethyltoluene diamine and carry out a curing reaction. At the same time, mix with polyether modified silicone oil defoamer for defoaming treatment. The curing reaction can be carried out at 15°C by uniformly stirring at 500r / min for 10min.

[0112] Example 5

[0113] The high-temperature resistant, low-viscosity, solid-free gel for repairing microcracks in oil and gas well cement sheaths is prepared from raw materials including the following components: 65 parts by weight of MF2133 special epoxy resin, 23.56 parts by weight of Heloxy_Modifier62 epoxy resin reactive diluent, 0.8 parts by weight of 550 silane coupling agent, 10 parts by weight of diethyltoluene diamine curing agent, and 0.64 parts by weight of polyether modified silicone oil.

[0114] The preparation method includes the following steps:

[0115] a16) Mix MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent to obtain diluted special epoxy resin; stir at 1600 r / min for 30 min at 10℃.

[0116] a17) The MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent mixture obtained in a16 are mixed with 550 silane coupling agent to obtain a special resin mixture; and stirred uniformly at 1200r / min for 10min at 12℃.

[0117] a18) Mix the MF2133 special epoxy resin, Heloxy_Modifier62 epoxy resin reactive diluent, and 550 silane coupling agent mixture from a17 with diethyltoluene diamine and carry out a curing reaction. At the same time, mix with polyether modified silicone oil defoamer for defoaming treatment. The curing reaction can be carried out at 18°C ​​by uniformly stirring at 500r / min for 8 minutes.

[0118] Example 6

[0119] The high-temperature resistant, low-viscosity, solid-free gel for repairing microcracks in oil and gas well cement sheaths is prepared from the following raw materials: 79 parts by weight of MF2133 special epoxy resin, 11.8 parts by weight of Heloxy_Modifier62 epoxy resin reactive diluent, 0.3 parts by weight of 550 silane coupling agent, 8.2 parts by weight of diethylformamide, and 0.7 parts by weight of polyether modified silicone oil.

[0120] The preparation method includes the following steps:

[0121] a19) Mix MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent to obtain diluted special epoxy resin; stir at 1500 r / min for 30 min at 20℃.

[0122] a20) The MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent mixture obtained in a19 are mixed with 550 silane coupling agent to obtain a special resin mixture; the mixture is stirred uniformly at 800 r / min for 10 min at 20°C.

[0123] a21) Mix the MF2133 special epoxy resin, Heloxy_Modifier62 epoxy resin reactive diluent, and 550 silane coupling agent mixture from a20 with diethylformamide and carry out a curing reaction. At the same time, mix with polyether modified silicone oil defoamer for defoaming treatment. The curing reaction can be carried out at 15°C by uniformly stirring at 500r / min for 10min.

[0124] Example 7

[0125] The high-temperature resistant, low-viscosity, solid-free gel for repairing microcracks in oil and gas well cement sheaths is prepared from the following raw materials: 79 parts by weight of MF2133 special epoxy resin, 11.8 parts by weight of Heloxy_Modifier62 epoxy resin reactive diluent, 0.3 parts by weight of 550 silane coupling agent, 8.2 parts by weight of diethyltoluene diamine, and 0.7 parts by weight of GPE type polyoxyethylene ether.

[0126] The preparation method includes the following steps:

[0127] a22) Mix MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent to obtain diluted special epoxy resin; stir at 1500 r / min for 30 min at 15℃.

[0128] a23) The MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent mixture obtained in a22 are mixed with 550 silane coupling agent to obtain a special resin mixture; the mixture is stirred uniformly at 900 r / min for 10 min at 15°C.

[0129] a24) Mix the MF2133 special epoxy resin, Heloxy_Modifier62 epoxy resin reactive diluent, and 550 silane coupling agent mixture from a23 with diethyltoluene diamine and carry out a curing reaction. At the same time, mix with GPE type polyoxyethylene ether defoamer for defoaming treatment. The curing reaction can be carried out at 10°C by uniformly stirring at 600r / min for 12min.

[0130] Comparative Example 1

[0131] The preparation method of the ordinary solid-free gel provided in this comparative example can be referred to Example 1, except that MF2133 special epoxy resin is not added, and Hein epoxy resin is used instead.

[0132] Comparative Example 2

[0133] The preparation method of the ordinary solid-free gel provided in this comparative example can be referred to Example 1, except that the Heloxy_Modifier62 epoxy resin reactive diluent is not added, and maleic anhydride is used instead.

[0134] Comparative Example 3

[0135] The preparation method of the ordinary solid-free gel provided in this comparative example can be referred to Example 1, except that MF2133 special epoxy resin and Heloxy_Modifier62 epoxy resin reactive diluent are not added, and hydantoin epoxy resin and maleic anhydride are used instead.

[0136] The properties of the repair gels or cured bodies obtained in each embodiment and comparative example are shown in Table 1. The permeability and bonding strength test results of the cured bodies obtained in the embodiments and comparative examples are shown in Table 2. The alkali resistance of the cured bodies is shown in Table 3, and the acid resistance is shown in Table 4.

[0137] Table 1. Performance of the repair gels or cured products obtained in the examples and comparative examples.

[0138]

[0139] As shown in Table 1, the difference between the comparative examples and the embodiments lies in the different resins or diluents. The resin of Comparative Example 1 is different from that of the embodiments, and the compressive strength of the cured body formed by Comparative Example 1 is significantly weaker than that of the embodiments, while the viscosity is higher. The diluent of Comparative Example 2 is different from that of the embodiments, and the Brookfield viscosity of the gel obtained in Comparative Example 2 before curing is much greater than that of the embodiments, while the compressive strength is weaker. Both the resin and diluent of Comparative Example 3 are different from those of the embodiments, and the Brookfield viscosity of the gel obtained in Comparative Example 3 before curing is much greater than that of the embodiments, while the compressive strength of the cured body formed is significantly weaker than that of the embodiments.

[0140] Compared to Example 1, Example 2 used a slightly larger amount of reactive diluent and a slightly smaller amount of curing agent. The gel prepared in Example 2 had a higher Brookfield viscosity than that in Example 1, a longer thickening time, and a lower compressive strength of the cured body. Compared to Example 1, Example 3 used a slightly larger amount of resin and a slightly smaller amount of curing agent. The gel prepared in Example 3 had a higher Brookfield viscosity and a higher compressive strength of the cured body than that in Example 1, and the thickening time increased with decreasing curing agent. Compared to Example 2, Example 4 used different amounts of coupling agent and defoamer, resulting in differences in the bonding properties and permeability of the cured body. Example 5 used a larger amount of curing agent, resulting in increased compressive strength and decreased thickening time. Examples 6 and 7 used curing agents and defoamers different from those in Example 1, resulting in a slight increase in Brookfield viscosity and a slight decrease in thickening time. In summary, the gels and curing agents obtained in Examples 1-7 all meet the requirements.

[0141] Table 2. Permeability and bonding strength of the cured bodies obtained in the examples and comparative examples.

[0142]

[0143] As shown in Table 2, compared with the cured body of the example, the cured body of the comparative example has a higher permeability and a lower interfacial bonding strength.

[0144] Table 3 Alkali resistance of the cured bodies obtained in the examples and comparative examples.

[0145]

[0146]

[0147] Table 4. Acid resistance properties of the cured bodies obtained in the examples and comparative examples.

[0148]

[0149] As shown in Tables 3 and 4, the cured bodies obtained in Example 1 and Comparative Example 1 were cured in 10% HCl solution and 1% NaOH solution for 6 days. The mass of the cured bodies did not change significantly, indicating that the cured bodies did not react with the acid and alkali solutions, thus demonstrating that the cured bodies have good acid and alkali resistance.

[0150] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A gel for repairing microcracks in the cement sheath of oil and gas wells, characterized in that, include: 65-85 parts by weight of glycidyl amine epoxy resin; 10-25 parts by weight of toluene glycidyl ether; Vinyltriisopropoxysilane 0.1 to 1.5 parts by weight; 5-10 parts by weight of curing agent.

2. The microcrack repair gel for oil and gas well cement sheaths according to claim 1, characterized in that, The glycidylamine epoxy resin is N,N-bis(glycidyl)aniline; the toluene glycidyl ether is 2-toluene glycidyl ether.

3. The microcrack repair gel for oil and gas well cement sheaths according to claim 1, characterized in that, The curing agent is one or more of tetrahydrophthalic anhydride, diethylformamide, melamine, and diethyltoluenediamine.

4. The microcrack repair gel for oil and gas well cement sheaths according to claim 1, characterized in that, It also includes 0.5 to 2.0 parts by weight of defoamer.

5. The microcrack repair gel for oil and gas well cement sheaths according to claim 4, characterized in that, The defoamer is a polyether-modified silicone oil defoamer or a GPE-type polyoxyethylene ether.

6. The microcrack repair gel for oil and gas well cement sheaths according to claim 1, characterized in that, include: 75-85 parts by weight of glycidyl amine epoxy resin; 10-18 parts by weight of toluene glycidyl ether; Vinyltriisopropoxysilane 0.1 to 1 part by weight; 6-10 parts by weight of curing agent.

7. The method for preparing the microcrack repair gel for oil and gas well cement sheaths according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Mix glycidyl amine epoxy resin and toluene glycidyl ether, and stir. Step 2: Mix the mixture obtained in Step 1 with vinyltriisopropoxysilane and stir to obtain a resin mixture; Step 3: The resin mixture is subjected to a curing reaction with a curing agent to obtain a microcrack repair gel for oil and gas well cement sheaths.

8. The method for preparing the microcrack repair gel for oil and gas well cement sheaths according to claim 7, characterized in that, Defoamer was also added during the curing reaction in step 3.

9. The method for preparing the microcrack repair gel for oil and gas well cement sheaths according to claim 7, characterized in that, The stirring speed in step 1 is 1400 r / min-1600 r / min, and the stirring speed in step 2 is 800 r / min-1200 r / min.

10. The method for preparing the microcrack repair gel for oil and gas well cement sheaths according to claim 7, characterized in that, The curing temperature in step 3 is 10-20℃, the curing time is 8-12 min, and the stirring is carried out at 400 r / min-600 r / min during the curing reaction.

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