Self-assembled nano anti-swelling sand control agent as well as preparation method and application thereof

Abstract

The invention provides a self-assembled nano anti-swelling sand control agent. The self-assembled nano anti-swelling sand control agent is prepared from the following components: 2.0%-6.0% of functional nano silicon dioxide, 0.2%-0.5% of a stabilizer and the balance of water. The invention also discloses a preparation method of the self-assembled nano anti-swelling sand control agent. The preparation method comprises the following steps: (1) preparing functional nano silicon dioxide; and (2) uniformly mixing the functional nano silicon dioxide, the stabilizer and the water at room temperature according to the formula proportion to obtain the self-assembled nano anti-swelling sand control agent. The invention further discloses application of the self-assembled nano anti-swelling sand control agent as an anti-swelling sand control agent in exploitation of a high-argillaceous loose sandstone reservoir. The self-assembled nano anti-swelling sand control agent is squeezed into a stratum as a pretreatment liquid in the sand control construction process, and is self-assembled on reservoir mineral and stratum fluid interfaces to form a single-layer adsorption film through multiple hydrogen bond driving and charge driving effects, so that hydration expansion of clay minerals and migration of silty-fine sand are inhibited, and efficient anti-swelling and sand control are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of sand control in oil and gas field development, and particularly relates to a self-assembled nano anti-swelling sand control agent, a preparation method thereof, and an application thereof. Background Art

[0002] Maintaining the stable seepage capacity of the reservoir is the key to the efficient development of highly argillaceous unconsolidated sandstone reservoirs. However, due to poor diagenesis and strong sensitivity of reservoir minerals, under factors such as high liquid production intensity and incompatibility of the fluid entering the well, reservoir fine particles are prone to expand and migrate, resulting in a decrease in the reservoir seepage capacity and low liquid production of oil wells.

[0003] Performing reservoir anti-swelling and sand inhibition pretreatment during sand control operations is an important means to solve the above problems, and the technical key lies in achieving a balance among efficient anti-swelling, sand control, and maintaining the reservoir seepage capacity.

[0004] Cationic polymers are currently widely used anti-swelling and sand inhibition systems. For example, Chinese invention patent CN 106753283B discloses a compound oil reservoir anti-swelling and sand inhibition agent, which is composed of the following raw materials in parts by weight: 20-30 parts of epichlorohydrin-trimethylamine polymer, 20-30 parts of cationic polyacrylamide, 20-30 parts of polydimethyldiallylammonium chloride, 37.5 parts of ammonium chloride, 3.75 parts of dibutyl phthalate, 2.27-2.75 parts of hydroxyethyl ethylenediamine, 1.0-1.25 parts of triethylenetetramine, 5-10 parts of graphite powder, 1-4 parts of methyl methacrylate, 2-5 parts of diethylene glycol monobutyl ether acetate, 2-5 parts of N-pentamethylene dithiocarbamate-zinc piperidine complex, and 5-10 parts of titanate coupling agent.

[0005] Another example is Chinese invention patent application CN105820808A, which discloses an anti-sand and anti-swelling agent and a preparation method thereof. The anti-sand and anti-swelling agent is compounded from an organic amine salt with an anti-swelling function and a terpolymer with an anti-sand function, and can effectively prevent clay swelling and fine silt sand production.

[0006] Although cationic polymers are widely used as anti-swelling and sand inhibition agents, there are still deficiencies: 1. The molecular weights are generally relatively high, which has a greater impact on the reservoir seepage capacity; 2. Cationic polymers mainly rely on electrostatic action to stabilize clay and fine silt sand, and the sand control performance is weak; 3. The components of the compound system are complex, and there is a chromatographic separation phenomenon during the migration in the reservoir, making it difficult to achieve uniform protection of the entire layer section.

[0007] Chinese invention patent CN111100290B discloses a preparation method of a vegetable oil asphalt cationic amide resin with dual functions of anti-swelling and sand control. The specific steps are as follows: (1) Vegetable oil asphalt and diamine react under the conditions of a catalyst and nitrogen protection at 90 °C and normal pressure for 2.0 hours; the temperature is raised to 200 °C and reacted at a pressure of 1.5 MPa for 2 hours; the pressure in the reaction kettle is reduced to normal pressure within 2 hours and then evacuated to carry out a decompression reaction for 1 hour to obtain an amide resin; (2) The vegetable oil asphalt amide resin is dissolved in xylene, and an excessive amount of methyl iodide or ethyl iodide or chloroethane or bromopropane is added dropwise and stirred at 90 °C for reaction; the product is washed with acetone and the solvent is evaporated to obtain a vegetable oil asphalt cationic amide resin. Compared with the conventional cationic polymer system, the anti-swelling and sand control ability of the vegetable oil asphalt cationic amide resin is greatly enhanced, and the chromatographic separation phenomenon in the reservoir migration process of the compound system is avoided. However, the above technical solutions have the following deficiencies: 1. The vegetable oil asphalt cationic amide resin needs to be dispersed in an organic solvent for use, with a low flash point and poor construction safety; 2. The organic solvent is volatile and has a great harm to the environment; 3. The molecular weights of resin products are generally high, which has a great impact on the reservoir seepage capacity. Summary of the Invention

[0008] Object of the Invention: Aiming at the deficiencies of the above-mentioned prior art, the present invention provides a self-assembled nano anti-swelling and sand control agent, its preparation method and application.

[0009] The self-assembled nano anti-swelling and sand control agent disclosed by the present invention is a water-based system, which can be injected into the formation as a pretreatment fluid during the sand control construction process, and has dual functions of anti-swelling and sand control. The functional nano-silica is modified with high-density hydrogen bond donor / acceptor groups and positive electric groups, and can form a monolayer adsorption film at the interface of reservoir minerals and formation fluids through multiple hydrogen bond driving and charge driving effects, inhibiting the hydration swelling of clay minerals and the migration of fine sand, and achieving the effect of regulating reservoir microparticles.

[0010] Technical Solution: A self-assembled nano anti-swelling and sand control agent, in terms of mass percentage, is composed of the following components:

[0011] 2.0%-6.0% of functional nano-silica, 0.2%-0.5% of stabilizer, and the balance is water.

[0012] Furthermore, the functional nano-silica contains structural unit A, structural unit B, structural unit C and structural unit D, where:

[0013] The structural unit A is derived from nano-silica;

[0014] The structural unit B is derived from a silane coupling agent containing a double bond;

[0015] The structural unit C is derived from isocyanate;

[0016] The structural unit D is derived from unsaturated alkyl ammonium chloride;

[0017] Based on the weight of the functional nano-silica, the content of the structural unit A is 79.37 - 88.5 wt%, the content of the structural unit B is 2.44 - 5.17 wt%, the content of the structural unit C is 4.13 - 8.47 wt%, and the content of the structural unit D is 4.13 - 8.47 wt%.

[0018] Furthermore, the silane coupling agent containing double bonds is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane.

[0019] Furthermore, the isocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, p-toluenesulfonyl isocyanate.

[0020] Furthermore, the unsaturated alkyl ammonium chloride is one or more of trimethyl(vinyl)ammonium chloride, dimethyldiallylammonium chloride, benzylvinyltrimethylammonium chloride.

[0021] Further, the stabilizer is a long alkyl chain hydrochloride, and the long alkyl chain hydrochloride is one or more of dodecyl hydrochloride, dodecyl acetate, 1-aminoethyl-2-undecylimidazoline hydrochloride, 1-aminoethyl-2-heptadecylimidazoline hydrochloride.

[0022] The preparation method of the above self-assembled nano anti-swelling and sand control agent is as follows:

[0023] (1) Prepare functional nano-silica;

[0024] (2) Mix the functional nano-silica, stabilizer, and water evenly at room temperature according to the formula ratio to obtain the self-assembled nano anti-swelling and sand control agent.

[0025] Further, by mass, step (1) includes the following steps:

[0026] (11) Prepare polymerizable nano-silica;

[0027] (12) Put 1 part of the polymerizable nano-silica prepared in step (11), 0.05 - 0.1 part of the functional monomer, and 0.05 - 0.1 part of the cationic monomer into a reaction vessel, and stir evenly to obtain a mixed solution;

[0028] (13) Slowly heat the mixed solution to 100 - 140 °C, hold the reaction for at least 4 h, and then filter and dry the product to obtain functional nano-silica.

[0029] Further, by mass, step (11) includes the following steps:

[0030] (111) Place 1 part of nano-silica, 0.03 - 0.06 part of interface enhancer, and 5 - 15 parts of water in a reaction vessel, and mix evenly to obtain a mixed solution;

[0031] (112) Adjust the pH value of the mixed solution to 5, then gradually heat it to 40 - 70 °C, hold the reaction for at least 2 h, and obtain polymerizable nano-silica after rotary evaporation, filtration, and drying.

[0032] Furthermore, the interface enhancer in step (111) is a double-bond-containing silane coupling agent, and the double-bond-containing silane coupling agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane.

[0033] Further, the functional monomer in step (12) is isocyanate, and the isocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, p-toluenesulfonyl isocyanate.

[0034] Further, the cationic monomer in step (12) is an unsaturated alkyl ammonium chloride, and the unsaturated alkyl ammonium chloride is one or more of trimethyl(vinyl)ammonium chloride, dimethyldiallylammonium chloride, benzylvinyltrimethylammonium chloride.

[0035] The self-assembled nano-swelling prevention and sand control agent is prepared by the preparation method described in any one of the above.

[0036] The application of the above self-assembled nano-swelling prevention and sand control agent as a swelling prevention and sand control agent in the exploitation of highly argillaceous unconsolidated sandstone reservoirs. This self-assembled nano-swelling prevention and sand control agent is injected into the formation as a pretreatment fluid during the sand control construction process, and through the action of multiple hydrogen bond driving and charge driving, a monolayer adsorption film is self-assembled at the interface of reservoir minerals and formation fluids, inhibiting the hydration swelling of clay minerals and the migration of fine sand, and achieving efficient swelling prevention and sand control.

[0037] The self-assembled nano-swelling prevention and sand control agent of the present invention can be injected into the formation as a pretreatment fluid during the sand control construction process. The surface of the functional nano-silica is modified with high-density hydrogen bond donor / acceptor groups and positive electric groups, and through the action of multiple hydrogen bond driving and charge driving, a monolayer adsorption film can be self-assembled at the interface of reservoir minerals and formation fluids, inhibiting the hydration swelling of clay minerals and the migration of fine sand, and achieving the effect of regulating reservoir fine particles.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. The functional nano-silica as the main agent is surface-modified with high-density hydrogen bond donor / acceptor groups and positively charged groups, and can form a monolayer adsorption film by self-assembly at the interface of reservoir minerals and formation fluids through multiple hydrogen bond driving and charge driving effects, inhibiting the hydration swelling of clay minerals and the migration of fine sand, and achieving efficient anti-swelling and sand control;

[0040] 2. A single system with dual functions of anti-swelling and sand control effectively avoids the chromatographic separation phenomenon of the compound system during the migration process in the reservoir, and can effectively achieve uniform protection of the entire layer section;

[0041] 3. The present invention is a water-based system with high flash points and fire points, and has high construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flowchart of the preparation method of the self-assembled nano anti-swelling and sand control agent disclosed by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0043] The following is a detailed description of the specific embodiments of the present invention.

[0044] The synthesis route of polymerizable nano-silica is as follows:

[0045]

[0046] The interfacial enhancer is a double-bond-containing silane coupling agent, and the double-bond-containing silane coupling agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, and γ-methacryloxypropyltrimethoxysilane.

[0047] The synthesis route of functional nano-silica is as follows:

[0048]

[0049] The functional monomer is an isocyanate, and the isocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, and p-toluenesulfonyl isocyanate.

[0050] The cationic monomer is an unsaturated alkyl ammonium chloride, and the unsaturated alkyl ammonium chloride is one or more of trimethyl(vinyl)ammonium chloride, dimethyldiallylammonium chloride, and benzylvinyltrimethylammonium chloride.

[0051] The "range" disclosed by the present invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The ranges defined in this way can include or exclude the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10 - 50 is listed for a specific parameter, ranges of 10 - 40 and 20 - 50 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In this application, unless otherwise stated, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations.

[0052] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

[0053] If there is no special instruction, all technical features and optional technical features of this application can be combined with each other to form new technical solutions.

[0054] If there is no special instruction, all steps of this application can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out in sequence, or can also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0055] If there is no special instruction, the "including" and "comprising" mentioned in this application mean open-ended, and can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or can also only include or comprise the listed components.

[0056] If there is no special instruction, the reaction is carried out under normal temperature and normal pressure conditions.

[0057] If there is no special instruction, all parts or percentages are by weight or weight percentage.

[0058] In the present invention, all the substances used are known substances and can be purchased or synthesized by known methods.

[0059] In the present invention, all the devices or equipment used are conventional devices or equipment known in the art and can be purchased.

[0060] A self-assembled nano anti-swelling sand control agent, calculated by mass percentage, consists of the following components:

[0061] Functional nano-silica 2.0% - 6.0%, stabilizer 0.2% - 0.5%, and the balance is water.

[0062] Furthermore, the functional nano-silica contains structural unit A, structural unit B, structural unit C, and structural unit D, where:

[0063] The structural unit A is derived from nano-silica;

[0064] The structural unit B is derived from a double-bonded silane coupling agent;

[0065] The structural unit C is derived from an isocyanate;

[0066] The structural unit D is derived from an unsaturated alkyl ammonium chloride;

[0067] Based on the weight of the functional nano-silica, the content of the structural unit A is 79.37 - 88.5 wt%, the content of the structural unit B is 2.44 - 5.17 wt%, the content of the structural unit C is 4.13 - 8.47 wt%, and the content of the structural unit D is 4.13 - 8.47 wt%.

[0068] Even further, the double-bonded silane coupling agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane.

[0069] Even further, the isocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, p-toluenesulfonyl isocyanate.

[0070] Even further, the unsaturated alkyl ammonium chloride is one or more of trimethyl(vinyl)ammonium chloride, dimethyldiallylammonium chloride, benzylvinyltrimethylammonium chloride.

[0071] Further, the stabilizer is a long alkyl chain hydrochloride, and the long alkyl chain hydrochloride is one or more of dodecyl hydrochloride, dodecyl acetate, 1-aminoethyl-2-undecylimidazoline hydrochloride, 1-aminoethyl-2-heptadecylimidazoline hydrochloride.

[0072] In one embodiment of the present invention, a self-assembled nano-swelling prevention and sand control agent is composed of the following components by mass percentage:

[0073] Functional nano-silica 2.0%, stabilizer 0.2%, and the balance is water.

[0074] Further, the functional nano-silica contains structural unit A, structural unit B, structural unit C, and structural unit D, where:

[0075] The structural unit A is derived from nano-silica;

[0076] The structural unit B is derived from a double-bond-containing silane coupling agent;

[0077] The structural unit C is derived from isocyanate;

[0078] The structural unit D is derived from an unsaturated alkyl ammonium chloride;

[0079] Based on the weight of the functional nano-silica, the content of the structural unit A is 79.37% by weight, the content of the structural unit B is 3.69% by weight, the content of the structural unit C is 8.47% by weight, and the content of the structural unit D is 8.47% by weight.

[0080] Even further, the double-bond-containing silane coupling agent is vinyltrimethoxysilane.

[0081] Even further, the isocyanate is toluene diisocyanate.

[0082] Even further, the unsaturated alkyl ammonium chloride is trimethyl(vinyl)ammonium chloride.

[0083] Further, the stabilizer is a long alkyl chain hydrochloride, and the long alkyl chain hydrochloride is dodecyl hydrochloride.

[0084] In another embodiment of the present invention, a self-assembled nano-swelling prevention and sand control agent is composed of the following components by mass percentage:

[0085] Functional nano-silica 6.0%, stabilizer 0.5%, and the balance is water.

[0086] Further, the functional nano-silica contains structural unit A, structural unit B, structural unit C, and structural unit D, where:

[0087] The structural unit A is derived from nano-silica;

[0088] The structural unit B is derived from a double-bond-containing silane coupling agent;

[0089] The structural unit C is derived from isocyanate;

[0090] The structural unit D is derived from unsaturated alkyl ammonium chloride;

[0091] Based on the weight of the functional nano-silica, the content of the structural unit A is 88.5 wt%, the content of the structural unit B is 2.44 wt%, the content of the structural unit C is 4.53 wt%, and the content of the structural unit D is 4.53 wt%.

[0092] Furthermore, the double-bond-containing silane coupling agent is vinyltriethoxysilane.

[0093] Furthermore, the isocyanate is isophorone diisocyanate.

[0094] Furthermore, the unsaturated alkyl ammonium chloride is dimethyldiallylammonium chloride.

[0095] Further, the stabilizer is a long alkyl chain hydrochloride, and the long alkyl chain hydrochloride is dodecyl acetate.

[0096] In another embodiment of the present invention, a self-assembled nano anti-swelling and sand control agent is composed of the following components in mass percentage:

[0097] Functional nano-silica 3%, stabilizer 0.35%, and the balance is water.

[0098] Further, the functional nano-silica contains a structural unit A, a structural unit B, a structural unit C, and a structural unit D, wherein:

[0099] The structural unit A is derived from nano-silica;

[0100] The structural unit B is derived from a double-bond-containing silane coupling agent;

[0101] The structural unit C is derived from isocyanate;

[0102] The structural unit D is derived from unsaturated alkyl ammonium chloride;

[0103] Based on the weight of the functional nano-silica, the content of the structural unit A is 86.57 wt%, the content of the structural unit B is 5.17 wt%, the content of the structural unit C is 4.13 wt%, and the content of the structural unit D is 4.13 wt%.

[0104] Furthermore, the silane coupling agent containing double bonds is vinyltris(2-methoxyethoxy)silane. In another embodiment, the silane coupling agent containing double bonds is γ-methacryloxypropyltrimethoxysilane. In another embodiment, the silane coupling agent containing double bonds is a mixture of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, and γ-methacryloxypropyltrimethoxysilane in an equal mass ratio.

[0105] Furthermore, the isocyanate is p-toluenesulfonyl isocyanate. In another embodiment, the isocyanate is a mixture of toluene diisocyanate, isophorone diisocyanate, and p-toluenesulfonyl isocyanate in an equal mass ratio.

[0106] Furthermore, the unsaturated alkyl ammonium chloride is benzylvinyltrimethylammonium chloride. In another embodiment, the unsaturated alkyl ammonium chloride is a mixture of trimethyl(vinyl)ammonium chloride, dimethyldiallylammonium chloride, and benzylvinyltrimethylammonium chloride in an equal mass ratio.

[0107] Further, the stabilizer is a long alkyl chain hydrochloride, and the long alkyl chain hydrochloride is 1-aminoethyl-2-undecylimidazoline hydrochloride. In another embodiment, the stabilizer is a long alkyl chain hydrochloride, and the long alkyl chain hydrochloride is 1-aminoethyl-2-heptadecylimidazoline hydrochloride. In another embodiment, the stabilizer is a long alkyl chain hydrochloride, and the long alkyl chain hydrochloride is a mixture of dodecyl hydrochloride, dodecyl acetate, 1-aminoethyl-2-undecylimidazoline hydrochloride, and 1-aminoethyl-2-heptadecylimidazoline hydrochloride in an equal mass ratio.

[0108] The preparation method of the above self-assembled nano-swelling prevention and sand control agent is as follows:

[0109] (1) Prepare functional nano-silica;

[0110] (2) Mix the functional nano-silica, stabilizer, and water evenly at room temperature according to the formula ratio to obtain the self-assembled nano-swelling prevention and sand control agent.

[0111] Further, in parts by mass, step (1) includes the following steps:

[0112] (11) Prepare polymerizable nano-silica;

[0113] (12) Place 1 part of the polymerizable nano-silica prepared in step (11), 0.05 - 0.1 part of the functional monomer, and 0.05 - 0.1 part of the cationic monomer in a reaction vessel, and stir evenly to obtain a mixed solution;

[0114] (13) Slowly heat the mixture to 100 - 140 °C, hold the temperature for at least 4 h, and then filter and dry the product to obtain functional nano-silica.

[0115] Further, by mass, step (11) includes the following steps:

[0116] (111) Place 1 part of nano-silica, 0.03 - 0.06 parts of interfacial enhancer, and 5 - 15 parts of water in a reaction vessel, mix evenly to obtain a mixture.

[0117] (112) Adjust the pH value of the mixture to 5, then gradually heat to 40 - 70 °C, hold the temperature for at least 2 h, and obtain polymerizable nano-silica after rotary evaporation, filtration, and drying.

[0118] Even further, the interfacial enhancer in step (111) is a double-bond-containing silane coupling agent, and the double-bond-containing silane coupling agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane.

[0119] Further, the functional monomer in step (12) is an isocyanate, and the isocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, p-toluenesulfonyl isocyanate.

[0120] Further, the cationic monomer in step (12) is an unsaturated alkyl ammonium chloride, and the unsaturated alkyl ammonium chloride is one or more of trimethyl(vinyl)ammonium chloride, dimethyldiallylammonium chloride, benzylvinyltrimethylammonium chloride.

[0121] The self-assembled nano-swelling prevention and sand control agent is prepared by the preparation method described in any one of the above.

[0122] In an embodiment of the present invention, the preparation method of the above self-assembled nano-swelling prevention and sand control agent is specifically as follows:

[0123] (1) Prepare functional nano-silica.

[0124] (2) Mix functional nano-silica, stabilizer, and water evenly at room temperature according to the formula ratio to obtain the self-assembled nano-swelling prevention and sand control agent.

[0125] Further, by mass, step (1) includes the following steps:

[0126] (11) Prepare polymerizable nano-silica.

[0127] (12) Place 1 part of the polymerizable nano-silica prepared in step (11), 0.05 part of the functional monomer, and 0.05 part of the cationic monomer in a reaction vessel, and obtain a mixed solution after stirring evenly;

[0128] (13) Slowly heat the mixed solution to 100 °C, keep the temperature for reaction for 8 h, and then filter and dry the product to obtain the functional nano-silica.

[0129] Furthermore, by mass parts, step (11) includes the following steps:

[0130] (111) Place 1 part of nano-silica, 0.03 part of the interfacial enhancer, and 5 parts of water in a reaction vessel, and obtain a mixed solution after mixing evenly;

[0131] (112) Adjust the pH value of the mixed solution to 5, then gradually heat it to 40 °C, keep the temperature for reaction for 6 h, and obtain the polymerizable nano-silica after rotary evaporation, filtration, and drying.

[0132] Even further, the interfacial enhancer in step (111) is a double-bond-containing silane coupling agent, and the double-bond-containing silane coupling agent is vinyltrimethoxysilane.

[0133] Furthermore, the functional monomer in step (12) is isocyanate, and the isocyanate is toluene diisocyanate.

[0134] Furthermore, the cationic monomer in step (12) is an unsaturated alkyl ammonium chloride, and the unsaturated alkyl ammonium chloride is trimethyl(vinyl)ammonium chloride.

[0135] The self-assembled nano-swelling prevention and sand control agent is prepared by the above preparation method.

[0136] In an embodiment of the present invention, the preparation method of the above self-assembled nano-swelling prevention and sand control agent specifically includes the following steps:

[0137] (1) Prepare functional nano-silica;

[0138] (2) Mix the functional nano-silica, the stabilizer, and water evenly at room temperature according to the formula ratio to obtain the self-assembled nano-swelling prevention and sand control agent.

[0139] Furthermore, by mass parts, step (1) includes the following steps:

[0140] (11) Prepare polymerizable nano-silica;

[0141] (12) Place 1 part of the polymerizable nano-silica prepared in step (11), 0.1 part of the functional monomer, and 0.1 part of the cationic monomer in a reaction vessel, and obtain a mixed solution after stirring evenly;

[0142] (13) Slowly heat the mixture to 140 °C, hold the reaction for 4 h, then filter and dry the product to obtain functional nano-silica.

[0143] Further, by mass, step (11) includes the following steps:

[0144] (111) Place 1 part of nano-silica, 0.06 part of interface enhancer, and 15 parts of water in a reaction vessel, and mix evenly to obtain a mixture.

[0145] (112) Adjust the pH value of the mixture to 5, then gradually heat to 70 °C, hold the reaction for 2 h, and obtain polymerizable nano-silica after rotary evaporation, filtration, and drying.

[0146] Even further, the interface enhancer in step (111) is a double-bond-containing silane coupling agent, and the double-bond-containing silane coupling agent is vinyltriethoxysilane.

[0147] Further, the functional monomer in step (12) is isocyanate, and the isocyanate is isophorone diisocyanate.

[0148] Further, the cationic monomer in step (12) is an unsaturated alkyl ammonium chloride, and the unsaturated alkyl ammonium chloride is dimethyldiallylammonium chloride.

[0149] The self-assembled nano-swelling prevention and sand control agent is prepared by the above preparation method.

[0150] In an embodiment of the present invention, the preparation method of the above self-assembled nano-swelling prevention and sand control agent specifically includes the following steps:

[0151] (1) Prepare functional nano-silica.

[0152] (2) Mix 1 part of the functional nano-silica prepared in step (1), 0.07 part of stabilizer, and water evenly at room temperature according to the formula ratio to obtain the self-assembled nano-swelling prevention and sand control agent.

[0153] Further, by mass, step (1) includes the following steps:

[0154] (11) Prepare polymerizable nano-silica.

[0155] (12) Place 1 part of the polymerizable nano-silica prepared in step (11), 0.07 part of functional monomer, and 0.07 part of cationic monomer in a reaction vessel, and stir evenly to obtain a mixture.

[0156] (13) Slowly heat the mixture to 120 °C, hold for 5 h, then filter and dry the product to obtain functional nano-silica.

[0157] Furthermore, by mass, step (11) includes the following steps:

[0158] (111) Place 1 part of nano-silica, 0.04 part of interfacial enhancer, and 10 parts of water in a reaction vessel, mix evenly to obtain a mixture;

[0159] (112) Adjust the pH value of the mixture to 5, then gradually heat to 60 °C, hold for 3 h, and obtain polymerizable nano-silica after rotary evaporation, filtration, and drying.

[0160] Even further, the interfacial enhancer in step (111) is a double-bond-containing silane coupling agent, and the double-bond-containing silane coupling agent is vinyltris(2-methoxyethoxy)silane. In another embodiment, the interfacial enhancer in step (111) is a double-bond-containing silane coupling agent, and the double-bond-containing silane coupling agent is γ-methacryloxypropyltrimethoxysilane. In another embodiment, the interfacial enhancer in step (111) is a double-bond-containing silane coupling agent, and the double-bond-containing silane coupling agent is a mixture of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, and γ-methacryloxypropyltrimethoxysilane in equal mass ratio.

[0161] Furthermore, the functional monomer in step (12) is isocyanate, and the isocyanate is p-toluenesulfonyl isocyanate. In another embodiment, the functional monomer in step (12) is isocyanate, and the isocyanate is a mixture of toluene diisocyanate, isophorone diisocyanate, and p-toluenesulfonyl isocyanate in equal mass ratio.

[0162] Furthermore, the cationic monomer in step (12) is unsaturated alkyl ammonium chloride, and the unsaturated alkyl ammonium chloride is benzylvinyltrimethylammonium chloride. In another embodiment, the cationic monomer in step (12) is unsaturated alkyl ammonium chloride, and the unsaturated alkyl ammonium chloride is a mixture of trimethyl(vinyl)ammonium chloride, dimethyldiallylammonium chloride, and benzylvinyltrimethylammonium chloride in equal mass ratio.

[0163] The self-assembled nano-swelling control sand control agent is prepared by the above method.

[0164] The present invention also discloses the application of the above self-assembled nano-swelling prevention and sand control agent as a swelling prevention and sand control agent in the exploitation of highly argillaceous unconsolidated sandstone reservoirs. During the sand control construction process, the self-assembled nano-swelling prevention and sand control agent is injected into the formation as a pretreatment fluid, and through multiple hydrogen bond driving and charge driving effects, a monolayer adsorption film is self-assembled at the interface of reservoir minerals and formation fluids, inhibiting the hydration swelling of clay minerals and the migration of fine sand, and achieving efficient swelling prevention and sand control.

[0165] Example 1

[0166] The preparation of the self-assembled nano-swelling prevention and sand control agent includes the following steps:

[0167] (1) Preparation of functional nano-silica: Using polymerizable nano-silica, functional monomers, and cationic monomers as raw materials, functional nano-silica is obtained through grafting reaction. Its specific preparation steps include:

[0168] ① Take 50 g of polymerizable nano-silica, 2.5 g of isophorone diisocyanate, and 2.5 g of vinyltrimethylammonium chloride and place them in a three-necked flask, with the mass ratio of the three being 1:0.05:0.05;

[0169] ② Slowly raise the temperature to 100 °C and keep the reaction for 4 h to obtain functional nano-silica.

[0170] (2) Preparation of the self-assembled nano-swelling prevention and sand control agent: Take functional nano-silica with a mass percentage of 2.0%, dodecyl hydrochloride with a mass percentage of 0.2%, and 97.8% of clear water, and mix them at room temperature to prepare the self-assembled nano-swelling prevention and sand control agent.

[0171] Furthermore, the preparation of polymerizable nano-silica:

[0172] The nano-silica is surface-modified through an interfacial enhancer, and polymerizable nano-silica is obtained through hydrolysis and condensation reactions. Its specific preparation steps include:

[0173] ① Take 50 g of nano-silica and 1.5 g of vinyltrimethoxysilane and place them in a three-necked flask, with the mass ratio of the two being 1:0.03. Add 463.5 g of clear water as a solvent to the reaction system. The total mass ratio of nano-silica and vinyltrimethoxysilane to the mass of the solvent water is 10:90;

[0174] ② Adjust the pH value of the reaction system to 5 and gradually raise the temperature to 40 °C;

[0175] ③ Keep the reaction for 2 h to obtain polymerizable nano-silica.

[0176] Example 2

[0177] The preparation of the self-assembled nano-swelling prevention and sand control agent includes the following steps:

[0178] (1) Preparation of functional nano-silica: Using polymerizable nano-silica, functional monomers and cationic monomers as raw materials, functional nano-silica is obtained through grafting reaction. The specific preparation steps are as follows:

[0179] ① Take 50 g of polymerizable nano-silica, 3.75 g of toluene diisocyanate and 3.75 g of dimethyldiallylammonium chloride and place them in a three-necked flask, where the mass ratio of the three is 1:0.075:0.075;

[0180] ② Slowly heat up to 120 °C and keep the reaction for 6 h to obtain functional nano-silica.

[0181] (2) Preparation of self-assembled nano-swelling prevention and sand control agent: Take 3.0% of functional nano-silica, 0.3% of dodecyl acetate and 96.7% of clear water by mass percentage, and mix them at room temperature to prepare a self-assembled nano-swelling prevention and sand control agent.

[0182] Furthermore, the preparation of polymerizable nano-silica: The nano-silica is surface-modified through an interfacial enhancer, and polymerizable nano-silica is obtained through hydrolysis and condensation reactions. The specific preparation steps are as follows:

[0183] ① Take 50 g of nano-silica and 2.5 g of vinyltriethoxysilane and place them in a three-necked flask, and the mass ratio of the two is 1:0.05. Add 472.5 g of clear water to the reaction system as a solvent. The total mass ratio of nano-silica and vinyltriethoxysilane to the mass of the solvent water is 10:90;

[0184] ② Adjust the pH value of the reaction system to 5 and gradually heat up to 50 °C;

[0185] ③ Keep the reaction for 3 h to obtain polymerizable nano-silica.

[0186] Example 3

[0187] The preparation of the self-assembled nano-swelling prevention and sand control agent includes the following steps:

[0188] (1) Preparation of functional nano-silica: Using polymerizable nano-silica, functional monomers and cationic monomers as raw materials, functional nano-silica is obtained through grafting reaction. The specific preparation steps are as follows:

[0189] ① Take 50 g of polymerizable nano-silica, 3.75 g of toluene diisocyanate and 3.75 g of dimethyldiallylammonium chloride and place them in a three-necked flask, where the mass ratio of the three is 1:0.075:0.075;

[0190] ② Slowly heat up to 120 °C and keep the temperature for 6 h to obtain functional nano-silica.

[0191] (2) Preparation of self-assembled nano-swelling prevention and sand control agent: Take 5.0% of functional nano-silica, 0.4% of 1-aminoethyl-2-undecylimidazoline hydrochloride, and 94.6% of clear water by mass percentage, and mix them at room temperature to prepare a self-assembled nano-swelling prevention and sand control agent.

[0192] Furthermore, the preparation of polymerizable nano-silica: Surface-modify nano-silica with an interfacial enhancer, and obtain polymerizable nano-silica through hydrolysis and condensation reactions. The specific preparation steps include:

[0193] ① Take 50 g of nano-silica and 2.5 g of γ-methacryloxypropyltrimethoxysilane and place them in a three-necked flask, and the mass ratio of the two is 1:0.05. Add 472.5 g of clear water as a solvent to the reaction system. The total mass ratio of nano-silica and γ-methacryloxypropyltrimethoxysilane to the mass of the solvent water is 10:90;

[0194] ② Adjust the pH value of the reaction system to 5 and gradually heat up to 60 °C;

[0195] ③ Keep the temperature for 3 h to obtain polymerizable nano-silica.

[0196] Example 4

[0197] The preparation of the self-assembled nano-swelling prevention and sand control agent includes the following steps:

[0198] (1) Preparation of functional nano-silica: Using polymerizable nano-silica, functional monomers and cationic monomers as raw materials, obtain functional nano-silica through grafting reactions. The specific preparation steps include:

[0199] ① Take 50 g of polymerizable nano-silica, 5 g of p-toluenesulfonyl isocyanate and 5 g of dimethyldiallylammonium chloride and place them in a three-necked flask, and the mass ratio of the three is 1:0.1:0.1;

[0200] ② Slowly heat up to 120 °C and keep the temperature for 8 h to obtain functional nano-silica.

[0201] (2) Preparation of self-assembled nano-swelling prevention and sand control agent: Take 5.0% of functional nano-silica, 0.4% of 1-aminoethyl-2-heptadecylimidazoline hydrochloride, and 94.6% of clear water by mass percentage, and mix them at room temperature to prepare a self-assembled nano-swelling prevention and sand control agent.

[0202] Further, (1) Preparation of polymerizable nano-silica: The nano-silica is surface-modified by an interfacial enhancer, and polymerizable nano-silica is obtained through hydrolysis and condensation reactions. The specific preparation steps are as follows:

[0203] ① Take 50 g of nano-silica and 3.0 g of vinyltris(2-methoxyethoxy)silane and place them in a three-necked flask, with a mass ratio of 1:0.06 between the two. Add 477 g of clear water to the reaction system as a solvent. The total mass of nano-silica and vinyltris(2-methoxyethoxy)silane to the mass of the solvent water is 10:90;

[0204] ② Adjust the pH value of the reaction system to 5 and gradually heat up to 60 °C;

[0205] ③ Keep the temperature for 4 h to obtain polymerizable nano-silica.

[0206] Example 5

[0207] Preparation of self-assembled nano-swelling control sand agent, including the following steps:

[0208] (1) Preparation of functional nano-silica: Using polymerizable nano-silica, functional monomer and cationic monomer as raw materials, functional nano-silica is obtained through grafting reaction. The specific preparation steps are as follows:

[0209] ① Take 50 g of polymerizable nano-silica, 5 g of p-toluenesulfonyl isocyanate and 5 g of benzylvinyltrimethylammonium chloride and place them in a three-necked flask, with a mass ratio of 1:0.1:0.1 among the three;

[0210] ② Slowly heat up to 140 °C and keep the temperature for 8 h to obtain functional nano-silica.

[0211] (2) Preparation of self-assembled nano-swelling control sand agent: Take 6.0% of functional nano-silica, 0.5% of 1-aminoethyl-2-undecylimidazoline hydrochloride and 93.5% of clear water by mass percentage, and mix them at room temperature to prepare the self-assembled nano-swelling control sand agent.

[0212] Further, preparation of polymerizable nano-silica: The nano-silica is surface-modified by an interfacial enhancer, and polymerizable nano-silica is obtained through hydrolysis and condensation reactions. The specific preparation steps are as follows:

[0213] ① Take 50 g of nano-silica and 3.0 g of vinyltris(2-methoxyethoxy)silane and place them in a three-necked flask, with a mass ratio of 1:0.06 between the two. Add 477 g of clear water to the reaction system as a solvent. The total mass of nano-silica and vinyltris(2-methoxyethoxy)silane to the mass of the solvent water is 10:90;

[0214] ②Adjust the pH value of the reaction system to 5 and gradually raise the temperature to 70 °C;

[0215] ③Keep the temperature for 4 h to obtain polymerizable nano-silica;

[0216] Test Example

[0217] Taking the self-assembled nano-swelling prevention and sand control agent prepared in Examples 1-5 as the research object, investigate its swelling prevention performance, sand control performance and the influence on seepage capacity respectively.

[0218] The specific test process is as follows: The self-assembled nano-swelling prevention and sand control agents prepared in Examples 1-5 are numbered 1#, 2#, 3#, 4#, and 5# in sequence, and evaluate their swelling prevention performance, sand control performance and the influence on seepage capacity according to Q / SH10202377-2020 "Technical Requirements for Sand Inhibitors" and Q / SH10201991-2018 "General Technical Conditions for Clay Stabilizers for Fracturing and Acidizing". The test results are shown in Table 1.

[0219] Table 1 Evaluation Results of Self-Assembled Nano-Swelling Prevention and Sand Control Agent

[0220] Number Anti-swelling rate, % Sand production, g / L (3000 mL / h) Permeability retention rate, % 1# 85.2％ 0.04 85.4％ 2# 85.2％ 0.02 88.7％ 3# 89.3％ 0.01 92.6％ 4# 90.6％ 0.00 91.5％ 5# 88.0％ 0.00 79.0％

[0221] The above test results show that the self-assembled nano-swelling prevention and sand control agent can effectively inhibit the hydration swelling of clay minerals and the migration of fine sand, and achieve efficient swelling prevention and sand control in highly argillaceous unconsolidated sandstone reservoirs.

[0222] The above has made a detailed description of the implementation mode of the present invention. However, the present invention is not limited to the above implementation mode, and various changes can be made without departing from the purpose of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A self-assembled nano-swelling prevention and sand control agent, characterized in that, by mass percentage, it is composed of the following components: functional nano-silica 2.0%-6.0%, stabilizer 0.2%-0.5%, and the balance is water.

2. The self-assembled nano-swelling prevention and sand control agent according to claim 1, characterized in that, the functional nano-silica contains structural unit A, structural unit B, structural unit C and structural unit D, wherein: the structural unit A is from nano-silica; the structural unit B is from a double-bond-containing silane coupling agent; the structural unit C is from isocyanate; the structural unit D is from an unsaturated alkyl ammonium chloride; based on the weight of the functional nano-silica, the content of the structural unit A is 79.37-88.5 wt%, the content of the structural unit B is 2.44-5.17 wt%, the content of the structural unit C is 4.13-8.47 wt%, and the content of the structural unit D is 4.13-8.47 wt%.

3. The self-assembled nano-swelling prevention and sand control agent according to claim 2, characterized in that, the double-bond-containing silane coupling agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane; the isocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, p-toluenesulfonyl isocyanate; the unsaturated alkyl ammonium chloride is one or more of trimethyl(vinyl)ammonium chloride, dimethyldiallylammonium chloride, benzylvinyltrimethylammonium chloride.

4. The self-assembled nano-swelling prevention and sand control agent according to claim 1, characterized in that, the stabilizer is a long alkyl chain hydrochloride, and the long alkyl chain hydrochloride is one or more of dodecyl hydrochloride, dodecyl acetate, 1-aminoethyl-2-undecylimidazoline hydrochloride, 1-aminoethyl-2-heptadecylimidazoline hydrochloride.

5. The preparation method of the self-assembled nano-swelling prevention and sand control agent according to any one of claims 1-4, characterized in that, the specific steps are as follows: (1). Prepare functional nano-silica; (2). Mix the functional nano-silica, stabilizer and water evenly at room temperature according to the formula ratio to obtain the self-assembled nano-swelling prevention and sand control agent.

6. The preparation method of the self-assembled nano-swelling prevention and sand control agent according to claim 5, characterized in that, by mass parts, step (1) includes the following steps: (11). Prepare polymerizable nano-silica; (12). Put 1 part of the polymerizable nano-silica prepared in step (11), 0.05-0.1 part of functional monomer, and 0.05-0.1 part of cationic monomer into a reaction vessel, stir evenly to obtain a mixed solution; (13). Slowly heat the mixed solution to 100-140 °C, keep the temperature for at least 4 h, and then filter and dry the product to obtain functional nano-silica.

7. The preparation method of the self-assembled nano-swelling prevention and sand control agent according to claim 6, characterized in that, Step (11) includes the following steps by mass parts: (111) Put 1 part of nano-silica, 0.03 - 0.06 part of interfacial enhancer, and 5 - 15 parts of water into a reaction vessel, and obtain a mixed solution after mixing evenly; (112) Adjust the pH value of the mixed solution to 5, then gradually raise the temperature to 40 - 70 °C, keep the temperature for at least 2 h, and obtain polymerizable nano-silica after rotary evaporation, filtration, and drying.

8. The preparation method of a self-assembled nano-swelling prevention and sand control agent according to claim 7, characterized in that the interfacial enhancer described in step (111) is a double-bond-containing silane coupling agent, and the double-bond-containing silane coupling agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane.

9. The preparation method of a self-assembled nano-swelling prevention and sand control agent according to claim 5, characterized in that the functional monomer described in step (12) is an isocyanate, and the isocyanate is one or more of toluene diisocyanate, isophorone diisocyanate, p-toluenesulfonyl isocyanate.

10. The preparation method of a self-assembled nano-swelling prevention and sand control agent according to claim 5, characterized in that the cationic monomer described in step (12) is an unsaturated alkyl ammonium chloride, and the unsaturated alkyl ammonium chloride is one or more of trimethyl(vinyl)ammonium chloride, dimethyldiallylammonium chloride, benzylvinyltrimethylammonium chloride.

11. A self-assembled nano-swelling prevention and sand control agent prepared by the preparation method described in any one of claims 5 - 10.

12. The application of the self-assembled nano-swelling prevention and sand control agent described in any one of claims 1 - 4, 11 as a swelling prevention and sand control agent in the exploitation of highly argillaceous unconsolidated sandstone reservoirs.

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