Amphoteric ion gel for profile control and raw material composition and preparation method thereof

Abstract

This invention discloses a zwitterionic gel for profile control, its raw material composition, and its preparation method. The raw material composition of the zwitterionic gel for profile control comprises, by weight: 10-30 parts acrylamide, 1-3 parts cationic monomer, 1-3 parts anionic monomer, 0.1-0.3 parts reinforcing agent, 0.2-0.5 parts pH adjuster, 0.02-0.05 parts chain transfer agent, 0.1-0.5 parts crosslinking agent, and 0.03-0.05 parts initiator; wherein the cationic monomer includes an organic quaternary ammonium salt containing an alkenyl group; the anionic monomer includes a compound containing an amide group, a sulfonic acid group, and an alkenyl group; the reinforcing agent includes an inorganic compound; and the crosslinking agent includes a compound containing two alkenyl groups and two phenyl groups, with the two alkenyl groups respectively linked to two phenyl groups. The zwitterionic gel for profile control of this invention possesses both high strength and high erosion resistance, exhibiting good sealing effect and sealing stability.

Description

Technical Field

[0001] This invention relates to a zwitterionic gel for profile control, its raw material composition, and its preparation method, belonging to the field of petrochemical technology. Background Technology

[0002] To effectively improve the reservoir heterogeneity of water-driven oilfields, various profile control systems, such as polymer gels, polymer microspheres, gel particles, and foams, have been developed over the years.

[0003] For example, US4834180A discloses an amino resin crosslinked polymer gel suitable for high-temperature reservoirs. US4476931A discloses the use of amphoteric polymer materials to reduce the water permeability of production formations. US5100952A discloses an organic crosslinked polyvinyl alcohol copolymer gel for harsh reservoir conditions.

[0004] CN110144199A discloses a polymer monodisperse nano-microsphere for deep-penetration regulation and its preparation method. The polymer monodisperse nano-microsphere for deep-penetration regulation comprises the following components by weight percentage: 0.05-2.5% of type A macromolecules, 0.05-2.5% of type B macromolecules, 0.002-0.05% of an oxygen scavenger, and the remainder being mineralized water. Type A macromolecules are linear water-soluble polymers with ethyl ether or propyl ether structures; type B macromolecules are water-soluble polymers with polyhydroxy or polyphenolic structures. During mixing, the aqueous solutions of type A and type B macromolecules undergo a strong supramolecular hydrogen bonding effect instantaneously. Driven by these strong hydrogen bonds, type A and type B macromolecules assemble intermolecularly, rapidly constructing a monodisperse nano-microsphere dispersion with controllable scale. This monodisperse nano-microsphere exhibits good permeation in porous media and excellent deep-penetration regulation capability.

[0005] CN117089012A discloses an aqueous dispersible phase nano-propulsion agent and its preparation method. This aqueous dispersible phase nano-propulsion agent is prepared by microemulsion polymerization using sodium dodecyl sulfonate and branched secondary alcohol polyoxyethylene ether as anionic-nonionic composite emulsifiers, n-butanol as a co-emulsifier, styrene and butyl acrylate as main monomers, 2-acrylamido-2-methylpropanesulfonic acid as a functional monomer, N,N-methyleneacrylamide as a crosslinking agent, and ammonium persulfate as an initiator. Compared to polyacrylamide microspheres with white oil as the dispersed phase prepared by reverse microemulsion polymerization, this aqueous dispersible phase nano-propulsion agent has advantages such as good water dispersibility and high strength, and can improve the performance of propulsion agents.

[0006] CN116063613A discloses an amphoteric polymer microsphere, its preparation method, and its applications. The raw materials for the polymer microspheres include water, acrylamide, diallylaminomethylphosphonate, ultrafine calcium carbonate, an amphoteric surfactant, alkanes, emulsifiers, initiators, hydrochloric acid, and an inorganic salt solution. The particle size of these amphoteric polymer microspheres is controllable in the nanoscale and exhibits high monodispersity, possessing advantages such as controllable particle size, strong temperature and salt resistance, good flexibility, and strong transport ability.

[0007] CN104371682A discloses an AA-AM-AMPS-DAC polymer gel water-blocking agent and its synthesis method, which is copolymerized from monomers acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and acryloyloxyethylammonium chloride, and has good temperature resistance, salt resistance and erosion resistance.

[0008] CN115322760A discloses an amphoteric hydroblocking and profile control agent and its preparation method. This amphoteric hydroblocking and profile control agent is prepared via reverse emulsion polymerization. The raw materials include an aqueous phase solution, an oil phase solution, and an initiator. The aqueous phase solution includes acrylamide, anionic monomers, cationic monomers, temperature-resistant and salt-resistant monomers, a crosslinking agent, a nano-reinforcing agent, a toughening agent, and water. The oil phase solution includes a base oil and an emulsifier. The nano-reinforcing agent is methacryloyloxysilane surface-modified nanoparticles. The toughening agent is at least one of glycidyl methacrylate grafted polylactic acid, acrylate grafted ethylene elastomer, or maleic anhydride grafted polyolefin elastomer. This amphoteric hydroblocking and profile control agent exhibits good shear resistance, good strength after swelling, and good sealing effect.

[0009] For fractured reservoirs, most existing particulate profile control agents are velocity-sensitive and cannot effectively plug fractures based on the principle of hydrogen bond adsorption and retention. Their scale-matching effect is insufficient to meet the waterflood profile improvement needs of reservoirs with strong heterogeneity and large permeability variations. This results in poor erosion resistance, significant susceptibility to micro-flow effects, and a short profile control period. Furthermore, existing particulate profile control agents struggle to balance high strength with high erosion resistance. Summary of the Invention

[0010] To address at least one of the aforementioned technical problems, the present invention aims to provide a zwitterionic gel for profile control, its raw material composition, and a preparation method thereof. The zwitterionic gel for profile control of the present invention possesses both high strength and high erosion resistance.

[0011] To achieve the above objectives, a first aspect of the present invention provides a raw material composition for a zwitterionic gel for profile control, comprising, by weight: 10-30 parts acrylamide, 1-3 parts cationic monomer, 1-3 parts anionic monomer, 0.1-0.3 parts reinforcing agent, 0.2-0.5 parts pH adjuster, 0.02-0.05 parts chain transfer agent, 0.1-0.5 parts crosslinking agent, and 0.03-0.05 parts initiator; wherein the cationic monomer comprises an organic quaternary ammonium salt containing an alkenyl group; the anionic monomer comprises a compound containing an amide group, a sulfonic acid group, and an alkenyl group; the reinforcing agent comprises an inorganic compound; and the crosslinking agent comprises a compound containing two alkenyl groups and two phenyl groups, wherein the two alkenyl groups are respectively attached to two phenyl groups.

[0012] According to a specific embodiment of the present invention, preferably, the cationic monomer comprises an organic quaternary ammonium salt containing a carbon chain with 12 or more carbon atoms and an alkenyl group. More preferably, the cationic monomer comprises one or more of dodecyl dimethyl allyl ammonium salt, hexadecyl dimethyl allyl ammonium salt, and octadecyl dimethyl allyl ammonium salt.

[0013] According to a specific embodiment of the present invention, preferably, the anionic monomer includes one or more of 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamidododecanesulfonic acid, 2-acrylamidotetradecanesulfonic acid and 2-acrylamidohexadecanesulfonic acid.

[0014] According to a specific embodiment of the present invention, preferably, the reinforcing agent includes one or more of modified clay, nano-silica, and nano-calcium carbonate. More preferably, the D50 particle size of the nano-silica and the nano-calcium carbonate is 50-300 nm, and the D50 particle size of the modified clay is 1-10 μm.

[0015] According to a specific embodiment of the present invention, preferably, the pH adjuster includes one or more of sodium acetate, sodium propionate, and sodium butyrate.

[0016] According to a specific embodiment of the present invention, preferably, the chain transfer agent includes one or two of sodium formate and sodium hypophosphite.

[0017] According to a specific embodiment of the present invention, preferably, the crosslinking agent includes one or more of 1,2-bis(4-vinylphenyl)ethane, 1,3-bis(4-vinylphenoxy)propane and 1,4-bis(4'-vinylphenoxy)butane.

[0018] According to a specific embodiment of the present invention, preferably, the initiator includes a redox initiator, wherein the oxidant in the redox initiator includes one or more of persulfate, hydrogen peroxide, tert-butyl hydrogen peroxide, cumene hydrogen peroxide, dicumene peroxide, di-tert-butyl peroxide, and tert-butyl peroxide, and the reducing agent in the redox initiator includes one or more of sulfite, bisulfite, metabisulfite, and ascorbic acid.

[0019] The second aspect of the present invention provides a method for preparing a zwitterionic gel for profile control, comprising the following steps: reacting the above-mentioned raw material composition for zwitterionic gel for profile control to obtain the zwitterionic gel for profile control.

[0020] According to a specific embodiment of the present invention, preferably, the preparation method includes the following steps: mixing anionic monomer, pH adjuster and water, and adjusting the pH value to 6-8 with an alkaline reagent to obtain a first solution; mixing acrylamide, cationic monomer, reinforcing agent, chain transfer agent, crosslinking agent and water to obtain a second solution; mixing the first solution and the second solution, and then adding an initiator and reacting under a protective gas atmosphere and at a temperature below 10°C, and after the reaction is completed, obtaining a reaction product; and post-processing the reaction product to obtain the zwitterionic gel for profile control.

[0021] According to a specific embodiment of the present invention, preferably, the post-processing includes solid-liquid separation, drying, granulation, and sieving.

[0022] A third aspect of the present invention provides a zwitterionic gel for profile control, which is prepared by the above-described method for preparing zwitterionic gels for profile control.

[0023] According to a specific embodiment of the present invention, preferably, the zwitterionic gel for profile control is granular with a D50 particle size of 200-500 μm.

[0024] The present invention has at least the following beneficial effects:

[0025] This invention employs an organic quaternary ammonium salt containing an alkenyl group as a cationic monomer, a compound containing an amide group, a sulfonic acid group, and an alkenyl group as an anionic monomer, an inorganic compound as a reinforcing agent, and a compound containing two alkenyl groups and two phenyl groups, with each alkenyl group attached to one of the two phenyl groups, as a crosslinking agent. Acrylamide monomer and a chain transfer agent are also used. These components work synergistically, enabling the zwitterionic gel particles of this invention to self-aggregate and exhibit profile control. Upon hydration and expansion, the particles increase in volume and possess elastic deformation capabilities. Through the synergistic effect of the components in the raw material composition of this invention, especially the synergistic effect between specific cationic monomers, anionic monomers, reinforcing agents and crosslinking agents, and acrylamide monomers and chain transfer agents, the electrostatic adsorption of the zwitterionic gel on negatively charged rock surfaces is enhanced, thereby improving its retention and erosion resistance. Furthermore, through their synergistic effect, the strength of the zwitterionic gel of this invention can be enhanced, thereby improving its shear resistance. This increases the physical sealing strength of the gel during profile control, such as blocking and bridging, avoiding the problems of poor retention and microscopic flow around the gel, which lead to a short effective period of profile control. It also avoids the problem of ineffective sealing due to shearing and breakage of gel particles. Therefore, the zwitterionic gel for profile control of this invention has both high strength and high erosion resistance, resulting in good sealing effect and sealing stability. Attached Figure Description

[0026] Figure 1 This is the infrared spectrum of the zwitterionic gel particles used for profile control in Example 1.

[0027] Figure 2 This is a particle size distribution diagram of the zwitterionic gel particles used for profile control in Example 1.

[0028] Figure 3 These are the stress-displacement curves of the gels in Example 1 and Comparative Example 1.

[0029] Figure 4 The curve shows the injection pressure change of the profile control agent prepared from zwitterionic gel particles in Example 1 during the displacement experiment. Detailed Implementation

[0030] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will now be described in detail below, but this should not be construed as limiting the scope of the invention.

[0031] It should be noted that, unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0033] It should be understood that the terms “comprising,” “including,” and / or “containing” as used herein specify the presence of the stated features, integers, steps, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

[0034] The endpoints and any values ​​of the ranges disclosed in this invention 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 in this invention.

[0035] According to a specific embodiment of the first aspect of the present invention, the present invention provides a raw material composition for a zwitterionic gel for profile control, comprising, by weight: 10-30 parts acrylamide, 1-3 parts cationic monomer, 1-3 parts anionic monomer, 0.1-0.3 parts reinforcing agent, 0.2-0.5 parts pH adjuster (preferably 0.2-0.3 parts), 0.02-0.05 parts chain transfer agent, 0.1-0.5 parts crosslinking agent, and 0.03-0.05 parts initiator (preferably 0.04-0.05 parts); wherein the cationic monomer comprises an organic quaternary ammonium salt containing an alkenyl group; the anionic monomer comprises a compound containing an amide group, a sulfonic acid group, and an alkenyl group; the reinforcing agent comprises an inorganic compound; and the crosslinking agent comprises a compound containing two alkenyl groups and two phenyl groups, wherein the two alkenyl groups are respectively connected to two phenyl groups.

[0036] In some embodiments, the cationic monomer comprises an organic quaternary ammonium salt containing a carbon chain of 12 or more carbon atoms and an alkenyl group. Preferably, the cationic monomer comprises one or more of dodecyl dimethyl allyl ammonium salt, hexadecyl dimethyl allyl ammonium salt, and octadecyl dimethyl allyl ammonium salt. Specifically, these organic quaternary ammonium salts may include ammonium chloride and / or ammonium bromide. More specifically, the cationic monomer comprises one or more of dodecyl dimethyl allyl ammonium chloride, hexadecyl dimethyl allyl ammonium chloride, and octadecyl dimethyl allyl ammonium chloride. The present invention preferably uses an organic quaternary ammonium salt containing a carbon chain of 12 or more carbon atoms and an alkenyl group as the cationic monomer, wherein the alkenyl group is a structural unit that reacts with the crosslinking agent of the present invention, and the carbon chain containing 12 or more carbon atoms can enhance the blocking ability, shear resistance, and toughness of the zwitterionic gel of the present invention. Specifically, when the zwitterionic gel of the present invention enters the pores, the longer carbon chain structure can wrap around the pores or intertwine to form a network structure, thereby enhancing the sealing ability. At the same time, the longer carbon chain structure can resist the damage of external forces through its own chain segment movement and intertwining, thereby improving shear resistance and toughness. When the ground pressure changes or the shear force generated by the fluid flow acts on the gel, the longer carbon chain structure can prevent the gel from being easily destroyed or falling off from the sealing position, thereby improving the stability of the gel and ensuring the durability of the profile control effect.

[0037] This invention uses compounds containing amide, sulfonic acid, and alkenyl groups as anionic monomers. The amide group exhibits strong hydrogen bonding adsorption and good hydrophilicity, while the sulfonic acid group demonstrates good salt resistance. The anionic monomers of this invention enable the zwitterionic gel to be better immobilized in pores, enhancing the sealing effect and improving the erosion resistance and stability of the zwitterionic gel. Simultaneously, it avoids agglomeration and precipitation during the injection process, allowing the zwitterionic gel to be uniformly dispersed in the fluid as smaller particles, better penetrating the micropores of the reservoir rock and improving sweep efficiency. In some embodiments, the anionic monomer includes one or more of 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-dodecanesulfonic acid, 2-acrylamido-tetradecanesulfonic acid, and 2-acrylamido-hexadecanesulfonic acid.

[0038] This invention introduces a reinforcing agent into a zwitterionic gel. During the reaction of each monomer, the reinforcing agent is distributed in the gel through various mechanisms such as van der Waals forces and hydrogen bonds, resulting in a significant improvement in gel strength. In some embodiments, the reinforcing agent includes one or more of modified clay, nano-silica, and nano-calcium carbonate. Preferably, the D50 particle size of the nano-silica and the nano-calcium carbonate is 50-300 nm, and the D50 particle size of the modified clay is 1-10 μm. Specifically, the modified clay includes organic modified clay, inorganic modified clay, and organic-inorganic composite modified clay. The organic modified clay preferably includes clay modified with an organic quaternary ammonium salt; the inorganic modified clay preferably includes clay modified with a metal salt. The organic quaternary ammonium salt used to modify the clay may include hexadecyltrimethylammonium chloride and / or octadecyltrimethylammonium bromide, etc. The metal salt used to modify the clay may include sodium salts, etc. The modification of clay can be carried out in accordance with conventional methods in the field, such as adding clay to a solution containing organic quaternary ammonium salts and / or sodium salts and stirring for a period of time, followed by solid-liquid separation, washing, drying, granulation and sieving to obtain modified clay.

[0039] In some embodiments, the pH adjuster includes one or more of sodium acetate, sodium propionate, and sodium butyrate.

[0040] By employing a chain transfer agent, this invention avoids excessive cross-linking of the zwitterionic gel, resulting in a more uniform and suitable degree of cross-linking, thereby improving the gel's strength and erosion resistance. In some embodiments, the chain transfer agent includes one or two of sodium formate and sodium hypophosphite, preferably sodium formate.

[0041] This invention employs a diene crosslinking agent containing two alkenyl groups and two phenyl groups, with each alkenyl group respectively linked to one of the two phenyl groups. This diene crosslinking agent can form complex connections with the acrylamide, anionic monomer, and cationic monomer of this invention, thereby forming a complex three-dimensional network crosslinking structure. This complex three-dimensional network crosslinking structure improves the shear resistance and toughness of the zwitterionic gel of this invention. When subjected to external forces caused by fluid scouring or changes in formation pressure, it has a better ability to disperse and buffer external forces, reducing gel breakage and detachment, thus achieving a better sealing effect. Moreover, this complex three-dimensional network crosslinking structure makes the expansion process of the zwitterionic gel of this invention more orderly and controllable, resulting in better expansion performance. Simultaneously, the aromatic ring portion of the diene crosslinking agent of this invention can also undergo non-polar adsorption such as π-π stacking with the rock surface, enhancing the adsorption performance of the gel. In some embodiments, the crosslinking agent includes one or more of 1,2-di(4-vinylphenyl)ethane, 1,3-di(4-vinylphenoxy)propane, and 1,4-di(4'-vinylphenoxy)butane. Preferably, the crosslinking agent is 1,4-bis(4'-vinylphenoxy)butane. The structural formula of 1,2-bis(4-vinylphenyl)ethane is: The structural formula of 1,3-bis(4-vinylphenoxy)propane is: The structural formula of 1,4-bis(4'-ethylenephenoxy)butane is: These crosslinking agents can be obtained commercially or prepared using methods in the prior art.

[0042] In this invention, 1,4-bis(4'-ethylenephenoxy)butane is preferably used as a crosslinking agent. It contains flexible segments, which not only improve the flowability, injection properties, blocking effect, and stability of the zwitterionic gel, but also further enhance its swelling properties, allowing the gel to have a controllable swelling rate and preventing excessive swelling. Furthermore, 1,4-bis(4'-ethylenephenoxy)butane also contains aryl ether groups, exhibiting good chemical stability and resistance to temperature changes, while simultaneously enhancing the adsorption performance of the zwitterionic gel.

[0043] In some embodiments, the initiator comprises a redox initiator, wherein the oxidizing agent in the redox initiator includes one or more of persulfate, hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, di-tert-butyl peroxide, and tert-butyl peroxide, and the reducing agent in the redox initiator includes one or more of sulfites, bisulfites, metabisulfites, and ascorbic acid. More preferably, the redox initiator comprises a combination of ammonium persulfate ((NH4)2S2O8) and sodium bisulfite (NaHSO3), wherein the mass ratio of ammonium persulfate to sodium bisulfite can be 1:(1.4-2).

[0044] According to a specific embodiment of the second aspect of the present invention, the present invention provides a method for preparing a zwitterionic gel for profile control, which includes the following steps: reacting the above-mentioned raw material composition of the zwitterionic gel for profile control to obtain the zwitterionic gel for profile control.

[0045] In some embodiments, the preparation method includes the following steps:

[0046] (1) Mix the anionic monomer, pH adjuster and water, and adjust the pH value to 6-8 with an alkaline reagent to obtain the first solution;

[0047] (2) Mix acrylamide, cationic monomer, reinforcing agent, crosslinking agent, chain transfer agent and water to obtain a second solution;

[0048] (3) Mix the first solution and the second solution, then add an initiator and react in a protective gas atmosphere at a temperature below 10°C. After the reaction is complete, the reaction product is obtained.

[0049] (4) The reaction product is post-processed to obtain the zwitterionic gel for profile control.

[0050] In some embodiments, the alkaline reagent may be, for example, a NaOH solution. The present invention does not impose special restrictions on the concentration of the NaOH solution, which can be routinely adjusted by those skilled in the art.

[0051] In some embodiments, the amount of water used in steps (1) and (2) can be conventionally adjusted by those skilled in the art, and the present invention does not impose any special restrictions on it.

[0052] In some embodiments, step (3) specifically includes: mixing the first solution and the second solution to obtain a third solution; then introducing a protective gas into the third solution (for 10-15 minutes) to expel air and lower the temperature of the third solution to below 10°C; then continuing to introduce the protective gas into the third solution and adding an oxidant aqueous solution, while controlling the system temperature to 6-8°C; continuing to introduce the protective gas for 5-10 minutes, adding a reducing agent aqueous solution, and recording the system temperature after the reducing agent aqueous solution is added; then continuing to introduce the protective gas for 5-10 minutes and stopping the introduction of the protective gas; then carrying out the reaction in a room temperature, sealed, and static environment, while testing the system temperature, and continuing the reaction for 1-1.5 hours after the system temperature no longer continues to rise, to obtain the reaction product. The protective gas may be, for example, nitrogen. The concentrations of the oxidant aqueous solution and the reducing agent aqueous solution can be conventionally adjusted by those skilled in the art, and this invention does not impose any special restrictions on them. The criterion for determining that the system temperature no longer continues to rise may include: if the system temperature changes by less than 5% within approximately 5 minutes, then the system temperature is considered to no longer rise.

[0053] In some embodiments, the post-processing includes solid-liquid separation, drying, granulation, and sieving. These post-processing steps can all be performed in accordance with conventional methods in the art, and the present invention does not specifically limit them, as long as an amphoteric gel meeting the particle size range of the present invention can be obtained. Granulation can be performed using methods such as a stirred ball mill.

[0054] According to a specific embodiment of the third aspect of the present invention, the present invention provides a zwitterionic gel for profile control, which is prepared by the above-described method for preparing zwitterionic gel for profile control.

[0055] The zwitterionic gel for profile control of the present invention contains various groups such as aromatic ether groups, amide groups, sulfonic acid groups, and ammonium groups, and preferably contains relatively long carbon chains. The synergistic effect between these groups gives the zwitterionic gel of the present invention excellent properties in many aspects, including high fluidity, injection and expansion performance, high salt resistance, temperature resistance and shear resistance, and strong adsorption performance. Therefore, the zwitterionic gel for profile control of the present invention has both high strength and high erosion resistance, and exhibits good plugging effect and plugging stability.

[0056] In some embodiments, the zwitterionic gel for profile control is granular with a D50 particle size (i.e., median particle size) of 200-500 μm.

[0057] The present invention is illustrated in detail below by way of examples, but the present invention is not limited to these examples. Of course, various modifications can be made within the scope of the present invention.

[0058] Test method:

[0059] Structural analysis of the gel particles: The instrument used was a Thermo Nicolet iS20 Fourier transform infrared spectrometer. Test conditions included a scanning range of 4000-400 cm⁻¹. -1 The number of scans was 32, and the resolution was 4cm. -1 Background acquisition mode. The preparation method of the test sample includes: mixing gel particles and potassium bromide powder at a mass ratio of 1:100, and then compressing the mixture into tablets to obtain the test sample.

[0060] D50 particle size of gel particles: The instrument used was a HORIBA LA-300 laser particle size analyzer. The preparation method and testing conditions for the test samples included: adding 100 mL of deionized water to a 250 mL beaker, stirring at 500 rpm using a 3 cm cylindrical magnetic stirrer to create a vortex; thoroughly mixing the gel particles, then using a 1 mL syringe to draw up the gel particles, and using a 0.0100 g ± 0.0010 g gel particles dropwise into the stirred deionized water using a differential weighing method, and dispersing for 5 minutes using a stopwatch to obtain the test sample; setting the "RRIndex" in the test parameters to 1.02-0.00i, using deionized water as a blank, adding it to a clean test cell, inserting it into the laser particle size analyzer, half-adjusting the optical path according to the instructions, and subtracting the background; then immediately adding the test sample to the sample cell, scanning to obtain the particle size distribution map; three parallel samples were prepared for each sample, and the average value was taken.

[0061] Example 1

[0062] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0063] (2) Add 10g acrylamide, 3.0g octadecyldimethylallylammonium chloride, 0.2g nano silica (D50 particle size of 100nm), 0.2g 1,4-bis(4'-vinylphenoxy)butane, 0.03g sodium formate and 75mL water to another 250mL three-necked flask in sequence. After stirring evenly, a second solution is obtained.

[0064] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath to lower the temperature of the third solution to below 10°C during this process; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.88g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.76g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0065] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain zwitterionic gel particles with a D50 particle size of 298 μm for profile control.

[0066] Figure 1 This is the infrared spectrum of the zwitterionic gel particles used for profile control in this embodiment. Figure 2 This is a particle size distribution diagram of the zwitterionic gel particles used for profile control in this embodiment. Figure 1 It can be seen that the zwitterionic gel particles in this embodiment contain the functional groups shown in Table 1.

[0067] Table 1

[0068]

[0069] Example 2

[0070] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0071] (2) Add 30g acrylamide, 3.0g octadecyldimethylallylammonium chloride, 0.3g nano silica (D50 particle size of 100nm), 0.5g 1,4-bis(4'-vinylphenoxy)butane, 0.05g sodium formate and 75mL water to another 250mL three-necked flask in sequence. After stirring evenly, a second solution is obtained.

[0072] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath to lower the temperature of the third solution to below 10°C during this process; then continue to introduce high-purity nitrogen gas into the third solution, and add 3.29 g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 6.58 g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0073] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain zwitterionic gel particles with a D50 particle size of 283 μm for profile control.

[0074] Example 3

[0075] (1) Add 52.5 mL of water to a 250 mL beaker, then add 1.0 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.28 g of sodium propionate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0076] (2) Add 15g acrylamide, 1.0g octadecyldimethylallylammonium chloride, 0.1g nano silica (D50 particle size of 100nm), 0.1g 1,4-bis(4'-vinylphenoxy)butane, 0.03g sodium formate and 75mL water to another 250mL three-necked flask in sequence. After stirring evenly, a second solution is obtained.

[0077] (3) Transfer the first solution to the second solution to obtain the third solution; then introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath to lower the temperature of the third solution to below 10°C during this process; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.89g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.79g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at the temperature for 1 hour to obtain the reaction product;

[0078] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain zwitterionic gel particles with a D50 particle size of 307 μm for profile control.

[0079] Example 4

[0080] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0081] (2) Add 10g acrylamide, 3.0g dodecyl dimethyl diallyl ammonium chloride, 0.2g nano calcium carbonate (D50 particle size of 100nm), 0.2g 1,4-bis(4'-vinylphenoxy)butane, 0.03g sodium formate and 75mL water to another 250mL three-necked flask in sequence. After stirring evenly, a second solution is obtained.

[0082] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath during this process to lower the temperature of the third solution to below 10°C; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.87g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.75g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0083] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain zwitterionic gel particles with a D50 particle size of 314 μm for profile control.

[0084] Example 5

[0085] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamidododecanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0086] (2) Add 10g acrylamide, 3.0g octadecyldimethylallylammonium chloride, 0.2g nano silica (D50 particle size of 100nm), 0.2g 1,2-bis(4-vinylphenyl)ethane, 0.03g sodium formate and 75mL water to another 250mL three-necked flask in sequence. After stirring evenly, a second solution is obtained.

[0087] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath during this process to lower the temperature of the third solution to below 10°C; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.87g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.75g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0088] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain zwitterionic gel particles with a D50 particle size of 276 μm for profile control.

[0089] Example 6

[0090] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0091] (2) Add 10g acrylamide, 3.0g octadecyldimethylallyl ammonium chloride, 0.2g modified clay (D50 particle size of 5μm), 0.2g 1,4-bis(4'-vinylphenoxy)butane, 0.03g sodium formate and 75mL water to another 250mL three-necked flask in sequence. After stirring evenly, a second solution is obtained. The modified clay used is hexadecyltrimethylammonium chloride modified clay, which is prepared by adding 100g clay to 1000mL of hexadecyltrimethylammonium chloride aqueous solution with a mass concentration of 5%, stirring at room temperature for 12h, and then filtering, washing, drying, granulating and sieving in a ball mill.

[0092] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath during this process to lower the temperature of the third solution to below 10°C; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.87g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.75g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0093] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain zwitterionic gel particles with a D50 particle size of 283 μm for profile control.

[0094] Example 7

[0095] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0096] (2) Add 10g acrylamide, 3.0g octadecyldimethylallylammonium chloride, 0.2g nano silica (D50 particle size of 100nm), 0.2g 1,2-bis(4-vinylphenyl)ethane, 0.03g sodium hypophosphite and 75mL water to another 250mL three-necked flask in sequence, stir well to obtain the second solution;

[0097] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath to lower the temperature of the third solution to below 10°C during this process; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.87g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.75g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0098] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain zwitterionic gel particles with a D50 particle size of 295 μm for profile control.

[0099] Comparative Example 1

[0100] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0101] (2) Add 10g acrylamide, 0.2g nano silica (D50 particle size of 100nm), 0.2g 1,4-bis(4'-vinylphenoxy)butane, 0.03g sodium formate and 75mL water to another 250mL three-necked flask in sequence, stir well to obtain the second solution;

[0102] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath to lower the temperature of the third solution to below 10°C during this process; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.88g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.76g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0103] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring to obtain gel particles for profile control with a D50 particle size of 306 μm.

[0104] Comparative Example 2

[0105] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0106] (2) Add 10g acrylamide, 3.0g dimethyl diallyl ammonium chloride, 0.2g nano silica (D50 particle size of 100nm), 0.2g 1,4-bis(4'-vinylphenoxy)butane, 0.03g sodium formate and 75mL water to another 250mL three-necked flask in sequence, stir well to obtain the second solution;

[0107] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath to lower the temperature of the third solution to below 10°C during this process; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.88g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.76g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0108] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain amphoteric gel particles with a D50 particle size of 288 μm for profile control.

[0109] Comparative Example 3

[0110] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0111] (2) Add 10g acrylamide, 3.0g octadecyldimethylallylammonium chloride, 0.2g nano silica (D50 particle size of 100nm), 0.2g 1,4-bis(4'-vinylphenoxy)butane and 75mL water to another 250mL three-necked flask in sequence, stir well to obtain the second solution;

[0112] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath to lower the temperature of the third solution to below 10°C during this process; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.88g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.76g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0113] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain zwitterionic gel particles with a D50 particle size of 296 μm for profile control.

[0114] Comparative Example 4

[0115] (1) Add 10g acrylamide, 3.0g octadecyldimethylallylammonium chloride, 0.2g nano silica (D50 particle size of 100nm), 0.2g 1,4-bis(4'-vinylphenoxy)butane, 0.03g sodium formate and 75mL water to a 250mL three-necked flask in sequence, stir well to obtain a reaction solution;

[0116] (2) High-purity nitrogen gas is introduced into the reaction solution for 10-15 minutes to purge air, and during this process, an ice-water bath is used to lower the temperature of the reaction solution to below 10°C; then, high-purity nitrogen gas is introduced into the reaction solution, and 2.88 g of 0.5% ammonium persulfate aqueous solution is added, while controlling the system temperature at 6-8°C; after introducing high-purity nitrogen gas for 5 minutes, 5.76 g of 0.5% sodium bisulfite aqueous solution is added, and the system temperature is recorded after the sodium bisulfite aqueous solution is added; then, high-purity nitrogen gas is introduced into the solution for 5-10 minutes, and then the introduction of high-purity nitrogen gas is stopped; then, the reaction is carried out in a sealed and static environment at room temperature, while the system temperature is tested. After the system temperature no longer rises, the reaction is continued at this temperature for 1.5 hours to obtain the reaction product;

[0117] (3) The reaction product is filtered, dried, granulated and sieved by a ball mill with stirring to obtain gel particles for profile control with a D50 particle size of 318 μm.

[0118] Comparative Example 5

[0119] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0120] (2) Add 10g acrylamide, 3.0g octadecyldimethylallylammonium chloride, 0.2g nano silica (D50 particle size of 100nm), 0.2g N,N-methylenebisacrylamide, 0.03g sodium formate and 75mL water to another 250mL three-necked flask in sequence, stir well to obtain the second solution;

[0121] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath to lower the temperature of the third solution to below 10°C during this process; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.88g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.76g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0122] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain zwitterionic gel particles with a D50 particle size of 283 μm for profile control.

[0123] Comparative Example 6

[0124] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0125] (2) Add 10g acrylamide, 3.0g octadecyldimethylallylammonium chloride, 0.2g 1,4-bis(4'-vinylphenoxy)butane, 0.03g sodium formate and 75mL water to another 250mL three-necked flask in sequence, stir well to obtain the second solution;

[0126] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath to lower the temperature of the third solution to below 10°C during this process; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.88g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.76g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0127] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring, to obtain zwitterionic gel particles with a D50 particle size of 315 μm for profile control.

[0128] Comparative Example 7

[0129] (1) Add 52.5 mL of water to a 250 mL beaker, then add 2.8 g of 2-acrylamido-2-methylpropanesulfonic acid and 0.3 g of sodium acetate, and then adjust the pH value to 6-8 with 3 mol / L NaOH solution to obtain the first solution;

[0130] (2) Add 10g acrylamide, 3.0g octadecyldimethylallylammonium chloride, 0.2g nano silica (D50 particle size of 100nm), 0.2g divinylbenzene, 0.03g sodium formate and 75mL water to another 250mL three-necked flask in sequence, stir well to obtain the second solution;

[0131] (3) Transfer the first solution to the second solution to obtain the third solution; then, introduce high-purity nitrogen gas into the third solution for 10-15 minutes to remove air, and use an ice-water bath to lower the temperature of the third solution to below 10°C during this process; then continue to introduce high-purity nitrogen gas into the third solution, and add 2.88g of 0.5% ammonium persulfate aqueous solution, while controlling the system temperature at 6-8°C; after continuing to introduce high-purity nitrogen gas for 5 minutes, add 5.76g of 0.5% sodium bisulfite aqueous solution, and record the system temperature after the sodium bisulfite aqueous solution is added; then continue to introduce high-purity nitrogen gas for 5-10 minutes, and then stop introducing high-purity nitrogen gas; then carry out the reaction in a sealed and static environment at room temperature, while testing the system temperature. After the system temperature no longer continues to rise, continue to keep the reaction at this temperature for 1.5 hours to obtain the reaction product;

[0132] (4) The reaction product is filtered, dried, granulated and sieved using a ball mill with stirring to obtain gel particles for profile control with a D50 particle size of 301 μm.

[0133] Test Example 1

[0134] The gels prepared in the above examples and comparative examples were subjected to gel strength tests. The test method included: cutting the ungranulated gel into dumbbell shapes (thickness × width × length = 3 × 4 × 25 mm) using a mold, and testing the tensile properties of the gel using a universal tensile testing machine (model: INSTRON 3366; country of origin: USA) at a tensile rate of 130 mm / min. The stress of each example and comparative example was 0.25 N / mm². 2 The displacements at that time are shown in Table 2. Figure 3 These are the stress-displacement curves of the gels in Example 1 and Comparative Example 1.

[0135] Table 2

[0136]

[0137]

[0138] From Table 2 and Figure 3 It can be seen that, under the same stress conditions, compared with comparative examples 1 to 7, the gel of embodiment 1 of the present invention has a shorter displacement and higher gel strength.

[0139] Test Example 2

[0140] The gel particles prepared in the above examples and comparative examples were subjected to sand-filled tube displacement experiments. The experimental method included the following steps: (1) Weigh about 10.0g of gel particles, add them to a 250mL beaker, and add 100mL of water and 10.0g of KCl as a protective agent. After stirring evenly, a profile control agent was obtained; (2) Select a sand-filled tube with a length of 50.0cm and a diameter of 2.5cm to simulate a core column with a permeability of 200mD. In an environment of 55℃, formation water was used to saturate the sand-filled tube. The injection rate was 0.5mL / min. When the injection pressure stabilized ( When the injection pressure hardly changes, it is considered that the injection is saturated. Then the permeability after water flooding (i.e., the permeability before profile control) is measured. (3) Then, 1.2 PV of profile control agent is injected into the sand-filled pipe after water flooding at an environment of 55°C at an injection rate of 0.5 mL / min. Then the permeability after profile control is measured. (4) Then, 15 PV of formation water is injected into the sand-filled pipe after profile control at an environment of 55°C for flushing at an injection rate of 0.5 mL / min. When water flow appears continuously at the outlet end of the sand-filled pipe, the injection pressure at this time is recorded. This pressure is the breakthrough pressure of the sand-filled pipe. Then the permeability after flushing is measured. The following formulas are used to calculate the plugging rate and plugging rate loss rate: Plugging rate (i.e., plugging rate before flushing) = (Permeability before profile adjustment - Permeability after profile adjustment) / Permeability before profile adjustment × 100%; Plugging rate loss rate = (Plugging rate before flushing - Plugging rate after flushing) / Plugging rate before flushing × 100%, where, Plugging rate after flushing = (Permeability before profile adjustment - Permeability after flushing) / Permeability before profile adjustment × 100%. The formation water salinity used is 20,000 ppm. The permeability calculation formula is based on Darcy's law, specifically: In the formula, K is the permeability, and the unit is m. 2 Q represents the fluid injection rate, measured in meters per second (m). 3 / s; μ is the viscosity of the fluid, in Pa·s; L is the seepage length, i.e., the filling length of the sand-filled pipe, in meters; A is the seepage cross-sectional area, i.e., the cross-sectional area of ​​the sand-filled pipe, in square meters. 2 △P represents the pressure difference between the two ends of the sand-filled pipe, in Pa.

[0141] The test results are shown in Table 3. Figure 4 The curve shows the injection pressure change of the profile control agent prepared by zwitterionic gel in Example 1 during the displacement experiment.

[0142] Table 3

[0143]

[0144] As can be seen from Table 3, the profile control gels in each comparative example omitted or replaced one or more of the raw materials in Example 1 of the present invention, resulting in a significant decrease in the plugging rate and a significant increase in the plugging rate loss rate of these comparative gels. In contrast, the zwitterionic gel used for profile control in the embodiments of the present invention possesses both high strength and high erosion resistance, exhibiting better plugging effect and plugging stability.

[0145] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A raw material composition for a zwitterionic gel for profile control, comprising, by weight: The composition comprises 10-30 parts acrylamide, 1-3 parts cationic monomer, 1-3 parts anionic monomer, 0.1-0.3 parts reinforcing agent, 0.2-0.5 parts pH adjuster, 0.02-0.05 parts chain transfer agent, 0.1-0.5 parts crosslinking agent, and 0.03-0.05 parts initiator; wherein the cationic monomer comprises an organic quaternary ammonium salt containing an alkenyl group; the anionic monomer comprises a compound containing an amide group, a sulfonic acid group, and an alkenyl group; the reinforcing agent comprises an inorganic compound; and the crosslinking agent comprises a compound containing two alkenyl groups and two phenyl groups, wherein the two alkenyl groups are respectively attached to two phenyl groups.

2. The raw material composition of the zwitterionic gel for profile control according to claim 1, wherein, The cationic monomer includes an organic quaternary ammonium salt containing a carbon chain with more than 12 carbon atoms and an alkenyl group.

3. The raw material composition of the zwitterionic gel for profile control according to claim 2, wherein, The cationic monomer includes one or more of dodecyl dimethyl allyl ammonium salt, hexadecyl dimethyl allyl ammonium salt, and octadecyl dimethyl allyl ammonium salt.

4. The raw material composition of the zwitterionic gel for profile control according to claim 1, wherein, The anionic monomer includes one or more of 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamidododecanesulfonic acid, 2-acrylamidotetradecanesulfonic acid, and 2-acrylamidohexadecanesulfonic acid.

5. The raw material composition of the zwitterionic gel for profile control according to claim 1, wherein, The reinforcing agent includes one or more of modified clay, nano-silica, and nano-calcium carbonate.

6. The raw material composition of the zwitterionic gel for profile control according to claim 5, wherein, The D50 particle size of the nano-silica and the nano-calcium carbonate is 50-300 nm, and the D50 particle size of the modified clay is 1-10 μm.

7. The raw material composition of the zwitterionic gel for profile control according to claim 1, wherein, The pH adjuster includes one or more of sodium acetate, sodium propionate, and sodium butyrate.

8. The raw material composition of the zwitterionic gel for profile control according to claim 1, wherein, The chain transfer agent includes one or both of sodium formate and sodium hypophosphite.

9. The raw material composition of the zwitterionic gel for profile control according to claim 1, wherein, The crosslinking agent includes one or more of 1,2-bis(4-vinylphenyl)ethane, 1,3-bis(4-vinylphenoxy)propane and 1,4-bis(4'-vinylphenoxy)butane.

10. The raw material composition of the zwitterionic gel for profile control according to claim 1, wherein, The initiator includes a redox initiator, wherein the oxidant in the redox initiator includes one or more of persulfate, hydrogen peroxide, tert-butyl hydrogen peroxide, cumene hydrogen peroxide, dicumene peroxide, di-tert-butyl peroxide, and tert-butyl peroxide, and the reducing agent in the redox initiator includes one or more of sulfite, bisulfite, metabisulfite, and ascorbic acid.

11. A method for preparing a zwitterionic gel for profile control, comprising the following steps: The zwitterionic gel for profile control is obtained by reacting the raw material composition of any one of claims 1-10.

12. The method for preparing zwitterionic gel for profile control according to claim 11, wherein, The preparation method includes the following steps: An anionic monomer, pH adjuster, and water are mixed, and the pH value is adjusted to 6-8 with an alkaline reagent to obtain a first solution. Acrylamide, cationic monomer, reinforcing agent, chain transfer agent, crosslinking agent, and water are mixed to obtain a second solution. The first solution and the second solution are mixed, and then an initiator is added and reacted under a protective gas atmosphere and at a temperature below 10°C. After the reaction is completed, a reaction product is obtained. The reaction product is post-processed to obtain the zwitterionic gel for profile control.

13. The method for preparing zwitterionic gel for profile control according to claim 12, wherein, The post-processing includes solid-liquid separation, drying, granulation, and sieving.

14. A zwitterionic gel for profile control, which is prepared by the method for preparing zwitterionic gel for profile control according to any one of claims 11-13.

15. The zwitterionic gel for profile control according to claim 14, wherein, The zwitterionic gel used for profile control is granular with a D50 particle size of 200-500 μm.

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