Profile control particle, preparation method and application thereof

Abstract

The present application relates to the technical field of oil exploration and development, and discloses a profile control particle, a preparation method and application thereof, the profile control particle comprises a copolymer and inorganic metal ions complexed on the copolymer, wherein the copolymer comprises a first structural unit provided by a backbone monomer, a second structural unit provided by a charged monomer and a third structural unit provided by a complexing monomer, and the inorganic metal ions are zirconium ions; the profile control particle has slow swelling property and high mechanical strength, and can realize deep profile control of a reservoir in an oil reservoir.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration and development technology, specifically to a profile control particle, its preparation method, and its application. Background Technology

[0002] Oilfield development can be divided into primary oil recovery (flowing oil recovery) relying on natural elastic energy, secondary oil recovery relying on water injection to replenish energy, tertiary oil recovery relying on chemical agents, and fourth or even fifth-stage oil recovery to further enhance the recovery rate after tertiary oil recovery. Primary oil recovery generally only recovers 5-20% of the original geological oil reserves; after secondary waterflooding, it generally recovers 20-40% of the original geological oil reserves; in complex reservoirs with high water cut, more than 30% of the residual oil remains unrecoverable even after tertiary oil recovery with chemical agents. Simultaneously, the heterogeneity of the reservoir combined with long-term water injection leads to the development of internal dominant channels, causing "short-circuiting" of active oil displacement agents, resulting in decreased oil production and increased production costs. To solve the "short-circuiting" problem and further improve oil production efficiency, injecting expanding particles through water injection wells to block dominant flow channels and thus adjust the flow profile is a current research hotspot. Deep profile control of oil reservoirs requires profile control particles to have high mechanical strength, high expansibility, and injectability. Cross-linked polyacrylamide-based polymer gel particles, when injected into high-permeability reservoir regions, can absorb water and swell to block areas with high permeability, thus forcing fluid flow to change direction, making them a highly effective profile control method. However, conventional gel particles, due to size limitations and continuous swelling during injection, are prone to inlet blockage and cannot penetrate deeper into the reservoir. Furthermore, highly swollen gel particles exhibit reduced mechanical strength or even breakage, making them unsuitable for complex reservoir environments. Increasing the concentration of cross-linking agent in the synthesized gel particle material is an effective method to improve its mechanical strength, but the introduction of high-concentration cross-linking agent leads to a decrease in the swelling ratio.

[0003] Therefore, high expansion ratio and high mechanical strength after expansion are two properties that are difficult for gel particles to possess simultaneously. Researching and developing a method for preparing nano-profiled particles that combine expansion and mechanical properties is of great significance in solving the problems of "inability to be injected," "limited travel distance," "inability to be blocked," and "low strength" of profiled particles. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of existing gel particles (profile control particles) that weaken or even break after absorbing water and swelling. This invention provides a profile control particle, its preparation method, and its application. The profile control particle has both slow expansion and high mechanical strength, and can achieve deep profile control of reservoirs in oil reservoirs.

[0005] To achieve the above objectives, a first aspect of the present invention provides profile-adjusting particles, wherein the profile-adjusting particles comprise a copolymer and inorganic metal ions complexed on the copolymer, wherein the copolymer comprises a first structural unit provided by a skeleton monomer, a second structural unit provided by a charged monomer, and a third structural unit provided by a complexing monomer, and the inorganic metal ions are zirconium ions.

[0006] A second aspect of the present invention provides a method for preparing the aforementioned profile-adjusting particles, wherein the preparation method includes:

[0007] (1) A dispersed phase is prepared by contacting a skeleton monomer, a charged monomer, a complex monomer, a salt containing inorganic metal ions, an initiator, a crosslinking agent and water;

[0008] (2) A continuous phase is prepared by contacting a surfactant and an organic solvent;

[0009] (3) Under ultrasonic conditions, the dispersed phase is added to the continuous phase to obtain a water-in-oil emulsion;

[0010] (4) The water-in-oil emulsion is heated to carry out free radical polymerization reaction, and then washed, centrifuged and dried to obtain profile-adjusting particles.

[0011] A third aspect of the present invention provides the application of the aforementioned profile-modifying particles as profile-modifying agents in oil reservoirs.

[0012] Through the above technical solution, the present invention achieves high expansibility while maintaining a certain mechanical strength by copolymerizing hydrophilic framework monomers, highly absorbent charged monomers, supramolecular complex monomers, and metal supramolecular complexes, thus exhibiting good formation shear resistance and solving the problem of weak mechanical strength or even breakage of traditional profile control particles after expansion. Attached Figure Description

[0013] Figure 1 This is a TEM image of the profiled particles with a core-shell structure prepared by the one-step method in Example 1 of this invention;

[0014] Figure 2 This is an enlarged TEM image of the profiled particles with a core-shell structure prepared by the one-step method in Example 1 of this invention;

[0015] Figure 3 This is a schematic diagram of the expansion ratio under different zirconium (Zr) concentrations in Comparative Example 1 and Examples 2-6 of the present invention;

[0016] Figure 4 This is a schematic diagram illustrating the effect of different zirconium addition amounts on mechanical strength properties after expansion for 7 days in Comparative Examples 1 and Examples 2-6 of the present invention.

[0017] Figure 5This is a schematic diagram illustrating the effect of different Ac concentrations on water absorption and swelling properties in Examples 5, 7, and 8 of the present invention;

[0018] Figure 6 This is a schematic diagram illustrating the effect of different Ac concentrations on mechanical strength after 7 days of expansion in Examples 5, 7, and 8 of the present invention;

[0019] Figure 7 This is a schematic diagram illustrating the effect of the amount of complex monomer added on water absorption and swelling properties in Examples 6, 9, and 10 of the present invention;

[0020] Figure 8 This is a schematic diagram illustrating the effect of the amount of complex monomer added on mechanical strength in Examples 6, 9, and 10 of the present invention. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] As previously stated, a first aspect of the present invention provides profile-adjusting particles, wherein the profile-adjusting particles comprise a copolymer and inorganic metal ions complexed on the copolymer, wherein the copolymer comprises a first structural unit provided by a skeleton monomer, a second structural unit provided by a charged monomer, and a third structural unit provided by a complexing monomer, and the inorganic metal ions are zirconium ions.

[0023] The inventors of this invention have discovered that by copolymerizing (hydrophilic) skeletal monomers, (hyperabsorbent) charged monomers, and (supramolecular) complex monomers, and then complexing them with inorganic metal ions (metal supramolecular), high expansibility can be achieved while maintaining a certain mechanical strength, resulting in good formation shear resistance. This solves the problem that traditional profile control particles have weak mechanical strength or even breakage after expansion.

[0024] Furthermore, by adjusting the content of metal ions and complex monomers, the expansion and mechanical strength of the particles can be controlled. In addition, nanoscale particles can be directly prepared by combining ultrasonic emulsification with high-speed dispersion, without the need for mechanical crushing of large gel blocks, thus making it more suitable for profile control in deep oil reservoirs.

[0025] According to the present invention, the skeleton monomer is acrylamide.

[0026] According to the present invention, the charged monomer includes one or more of 2-acrylamido-2-methylpropanesulfonic acid, sodium p-styrenesulfonate, (3-acrylamidopropyl)trimethylammonium chloride and acryloyloxyethyltrimethylammonium chloride.

[0027] According to the present invention, the complexing monomer comprises one or more of acrylic acid, methacrylic acid, maleic acid, itaconic acid and aconitic acid, which have a carboxyl group.

[0028] According to the present invention, based on the total structural units of the copolymer, the content of the first structural unit is 30-80 wt%, the content of the second structural unit is 10-50 wt%, and the content of the third structural unit is 1-30 wt%.

[0029] According to the present invention, preferably, based on the total structural units of the copolymer, the content of the first structural unit is 45-67.1 wt%, the content of the second structural unit is 20.9-49.3 wt%, and the content of the third structural unit is 5.7-21.8 wt%. In the present invention, the first, second, and third structural units form a covalently cross-linked copolymer through a free radical reaction.

[0030] According to the present invention, based on the total content of the copolymer, the content of the inorganic metal ions is 1-30 wt%, preferably 3.8-18.9 wt%. In the present invention, the supramolecular complex monomer and the inorganic metal ions form an ionic complex through supramolecular complexation.

[0031] According to the present invention, by using a combination of ultrasonic emulsification and stirring dispersion, the particle size of the profiled particles is less than 1 μm, preferably 90-100 nm, and more preferably 100 nm, instead of pulverizing large gel blocks by mechanical means.

[0032] According to the present invention, the profile-adjusting particles have slow expansion properties, and the expansion ratio of the profile-adjusting particles is ≤83.

[0033] According to the present invention, the compressive strength of the profile-adjusting particles after swelling in brine for 7 days can reach up to 0.99 MPa, that is, the compressive strength is ≤0.99 MPa.

[0034] A second aspect of the present invention provides a method for preparing the aforementioned profile-adjusting particles, wherein the preparation method includes:

[0035] (1) A dispersed phase is prepared by contacting a skeleton monomer, a charged monomer, a complex monomer, a salt containing inorganic metal ions, an initiator, a crosslinking agent and water;

[0036] (2) A continuous phase is prepared by contacting a surfactant and an organic solvent;

[0037] (3) Under ultrasonic conditions, the dispersed phase is added to the continuous phase to obtain a water-in-oil emulsion;

[0038] (4) The water-in-oil emulsion is heated to carry out free radical polymerization reaction, and then washed, centrifuged and dried to obtain profile-adjusting particles.

[0039] According to the present invention, the amounts of each material, in molar equivalents, include: 0.001-0.1M for the skeletal monomer, 0.0001-0.1M for the charged monomer, 0.0001-0.1M for the complexing monomer, 0.00001-0.001M for the salt containing inorganic metal ions, and 1×10⁻⁶ for the initiator. -5 Up to 1×10 -3 M; preferably, the skeletal monomer is 0.01-0.1M, the charged monomer is 0.001-0.003M, the complexing monomer is 0.001-0.003M, the inorganic metal ion salt is 0.0002-0.0007M, and the crosslinking agent is 1×10 -4 M to 1×10 -3 M, the initiator is 1×10 -4 M to 1×10 -3 M.

[0040] According to the present invention, the surfactant is Span80.

[0041] According to the present invention, the organic solvent is selected from one or more of cyclohexane, chloroform, n-hexane, dichloromethane, toluene, and ethyl acetate.

[0042] According to the present invention, the salt containing inorganic metal ions is selected from one or more of zirconium oxychloride, zirconium acetate, zirconium sulfate, zirconium chloride, zirconium silicate, and zirconium hydroxide.

[0043] According to the present invention, the crosslinking agent is N,N-methylenebisacrylamide.

[0044] According to the present invention, the initiator is ammonium persulfate.

[0045] According to the present invention, in step (3), the cells are ultrasonically dispersed for 3-5 minutes, preferably 5 minutes, using a cell disruptor.

[0046] According to the present invention, in step (4), the conditions for the free radical polymerization reaction include: a temperature of 50-80°C and a time of 60-300 min; preferably, a temperature of 65-75°C and a time of 80-180 min; more preferably, heating at 70°C for 90 min. Preferably, the free radical polymerization reaction is carried out under stirring conditions at a stirring speed of 500-1200 rpm / min, preferably 1000 rpm / min.

[0047] According to the present invention, in step (4), the centrifugation rate is 5000-7000 rpm / min and the centrifugation time is 5-10 min, preferably, the centrifugation rate is 6000-6500 rpm / min and the centrifugation time is 5-7 min. In addition, this process can be repeated 3-5 times, preferably 3 times.

[0048] According to the present invention, the reactants after step (4) are dried in an oven at 50-60°C for 24-30 hours.

[0049] According to a particularly preferred embodiment of the present invention, a method for preparing profile-adjusting particles includes:

[0050] (a) A dispersed phase is prepared by adding a hydrophilic skeleton monomer, a highly water-absorbent charged monomer, a supramolecular complex monomer, a salt containing inorganic metal ions, a crosslinking agent and an initiator to water;

[0051] (b) Prepare a continuous phase by adding a surfactant to a water-insoluble organic solvent;

[0052] (c) Add step (a) to step (b) to obtain a layered mixture, disperse it by ultrasonication, and obtain a stable water-in-oil emulsion;

[0053] (d) Place step (c) in a high-temperature water bath and stir at high speed to carry out free radical polymerization until the reaction is complete;

[0054] (e) Wash with plenty of ethanol after step (d);

[0055] (f) Centrifugation;

[0056] (g) Repeat the washing-centrifugation process;

[0057] (h) Dry and store for later use.

[0058] As a result, nano-profile particles with both expandability and high mechanical strength were prepared.

[0059] A third aspect of the present invention provides the application of the aforementioned profile-modifying particles as profile-modifying agents in oil reservoirs.

[0060] According to the present invention, the conditions suitable for the reservoir include: a temperature of 30-80℃ and a salinity of 0.1×10⁻⁶. 4 mg / L to 1×10 4 mg / L.

[0061] The present invention will be described in detail below through embodiments.

[0062] In the following examples and comparative examples:

[0063] The swelling ratio is calculated using the following formula, where W... s W is the weight of the gel after it has swelled. d The quality of the gel after drying.

[0064]

[0065] Mechanical strength (stress) was determined by compression testing at a rate of 5 mm / min.

[0066] In this invention, it should be noted that the mechanical strength is the mechanical strength measured at the end of the expansion.

[0067] Unless otherwise specified, all raw materials are analytical grade reagents purchased from Aladdin Reagent Co., Ltd.

[0068] Example 1

[0069] This embodiment illustrates profile-adjusting particles prepared using the method of the present invention.

[0070] The raw materials include: hydrophilic skeleton monomer acrylamide, metal supramolecular complex monomer acrylic acid (Ac), charged monomer 2-acrylamido-2-methylpropanesulfonic acid (Amps), conventional crosslinking agent N,N-methylenebisacrylamide, salt containing inorganic metal ions (metal supramolecular complex crosslinking agent) zirconium acetate, and free radical reaction initiator ammonium persulfate.

[0071] Preparation method:

[0072] (1) Acrylamide 0.008M, acrylic acid 0.001M, 2-acrylamido-2-methylpropanesulfonic acid 0.001M, N,N-methylenebisacrylamide (0.1% of total monomers), zirconium acetate 0.0004M, N,N-methylenebisacrylamide 1×10 -3 M, ammonium persulfate 2×10 -3 M, dissolve in 1g of water and stir thoroughly to dissolve;

[0073] (2) Dissolve Span80 (0.4g) in 10g cyclohexane and stir thoroughly;

[0074] (3) Add (1) to (2) and sonicate for 5 minutes;

[0075] (4) Place in a magnetic stirrer and heat in a 70°C water bath at 1000 rpm / min for 90 min;

[0076] (5) Add a large amount of ethanol to wash, centrifuge (centrifugation speed is 6000 rpm / min, centrifugation time is 5 min), repeat 3 times;

[0077] (6) Dry in a 50℃ oven for 24 hours.

[0078] The resulting nanogel particles, namely profiled particles, wherein, based on the total structural units of the copolymer, the content of the first structural unit is 67.1 wt%, the content of the second structural unit is 24.4 wt%, and the content of the third structural unit is 8.5 wt%; in addition, based on the total content of the copolymer, the content of the inorganic metal ions is 11 wt%.

[0079] Figure 1 This is a TEM image of the profiled particles prepared in Example 1 of this invention; Figure 2 These are TEM images of profiled particles with a core-shell structure prepared by the one-step method in Example 1 of this invention; from Figure 1 and Figure 2 It can be seen that the profile-adjusting particles prepared using the examples have a particle size (diameter) of less than 100 nm and are nanogel particles with a core-shell structure.

[0080] Comparative Example 1

[0081] This embodiment illustrates profile-adjusting particles prepared using the method of the present invention.

[0082] The raw materials include: acrylamide, a hydrophilic monomer with a skeleton; acrylic acid, a metal supramolecular complex monomer; 2-acrylamido-2-methylpropanesulfonic acid, a charged monomer; N,N-methylenebisacrylamide, a crosslinking agent; and ammonium persulfate, a free radical reaction initiator. In Comparative Example 1, the raw materials do not include zirconium acetate, a salt containing inorganic metal ions (a metal supramolecular complex crosslinking agent).

[0083] Preparation method:

[0084] (1) Acrylamide 0.008M, acrylic acid 0.001M, 2-acrylamido-2-methylpropanesulfonic acid 0.001M, zirconium acetate 0,N,N-methylenebisacrylamide 1×10 -3 M, ammonium persulfate 2×10 -3 M, dissolve in 1g of water and stir thoroughly to dissolve.

[0085] (2) Dissolve Span80 (0.4g) in 10g cyclohexane and stir thoroughly;

[0086] (3) Add (1) to (2) and sonicate for 5 minutes;

[0087] (4) Place in a magnetic stirrer and heat in a 70°C water bath at 1000 rpm / min for 90 min;

[0088] (5) Add a large amount of ethanol to wash, centrifuge (centrifugation speed is 6000 rpm / min, centrifugation time is 5 min), repeat 3 times;

[0089] (6) Dry in a 50℃ oven for 24 hours.

[0090] The resulting nanogel particles, namely profiled particles, have the following composition: based on the total structural units of the copolymer, the content of the first structural unit is 67.1 wt%, the content of the second structural unit is 24.4 wt%, and the content of the third structural unit is 8.5 wt%; furthermore, based on the total content of the copolymer, the content of inorganic metal ions is 0.

[0091] Example 2

[0092] This embodiment illustrates profile-adjusting particles prepared using the method of the present invention.

[0093] Profile-adjusting particles were prepared using the same method as in Example 1, except that "zirconium acetate 0.0004M" in Example 1 was replaced with "zirconium oxychloride 0.0001M".

[0094] The resulting nanogel particles, namely profiled particles, have the following composition: based on the total structural units of the copolymer, the content of the first structural unit is 67.1 wt%, the content of the second structural unit is 24.4 wt%, and the content of the third structural unit is 8.5 wt%; in addition, based on the total content of the copolymer, the content of the inorganic metal ions is 3.8 wt%.

[0095] Example 3

[0096] This embodiment illustrates profile-adjusting particles prepared using the method of the present invention.

[0097] Profile-adjusting particles were prepared using the same method as in Example 1, except that "zirconium acetate 0.0004M" in Example 1 was replaced with "zirconium oxychloride 0.0002M".

[0098] The resulting nanogel particles, namely profiled particles, have the following composition: based on the total structural units of the copolymer, the content of the first structural unit is 67.1 wt%, the content of the second structural unit is 24.4 wt%, and the content of the third structural unit is 8.5 wt%; in addition, based on the total content of the copolymer, the content of the inorganic metal ions is 7.6 wt%.

[0099] Example 4

[0100] This embodiment illustrates profile-adjusting particles prepared using the method of the present invention.

[0101] Profile-adjusting particles were prepared using the same method as in Example 1, except that "zirconium acetate 0.0004M" in Example 1 was replaced with "zirconium oxychloride 0.0003M".

[0102] The resulting nanogel particles, namely profiled particles, have the following composition: based on the total structural units of the copolymer, the content of the first structural unit is 67.1 wt%, the content of the second structural unit is 24.4 wt%, and the content of the third structural unit is 8.5 wt%; in addition, based on the total content of the copolymer, the content of the inorganic metal ions is 11.3 wt%.

[0103] Example 5

[0104] This embodiment illustrates profile-adjusting particles prepared using the method of the present invention.

[0105] Profile-adjusting particles were prepared using the same method as in Example 1, except that "zirconium acetate 0.0004M" in Example 1 was replaced with "zirconium oxychloride 0.0004M".

[0106] The resulting nanogel particles, namely profiled particles, have the following composition: based on the total structural units of the copolymer, the content of the first structural unit is 67.1 wt%, the content of the second structural unit is 24.4 wt%, and the content of the third structural unit is 8.5 wt%; in addition, based on the total content of the copolymer, the content of the inorganic metal ions is 15.1 wt%.

[0107] Example 6

[0108] This embodiment illustrates profile-adjusting particles prepared using the method of the present invention.

[0109] Profile-adjusting particles were prepared using the same method as in Example 1, except that "zirconium acetate 0.0004M" in Example 1 was replaced with "zirconium oxychloride (0.0005M)".

[0110] The resulting nanogel particles, namely profiled particles, have the following composition: based on the total structural units of the copolymer, the content of the first structural unit is 67.1 wt%, the content of the second structural unit is 24.4 wt%, and the content of the third structural unit is 8.5 wt%; in addition, based on the total content of the copolymer, the content of the inorganic metal ions is 18.9 wt%.

[0111] Example 7

[0112] This embodiment illustrates profile-adjusting particles prepared using the method of the present invention.

[0113] Profile-adjusting particles were prepared using the same method as in Example 1, except that "0.001M acrylic acid" in Example 1 was changed to "0.002M acrylic acid", and "zirconium acetate" in Example 1 was changed to "zirconium oxychloride".

[0114] The resulting nanogel particles, namely profiled particles, wherein, based on the total structural units of the copolymer, the content of the first structural unit is 61.8 wt%, the content of the second structural unit is 22.5 wt%, and the content of the third structural unit is 15.7 wt%; in addition, based on the total content of the copolymer, the content of the inorganic metal ions is 13.9 wt%.

[0115] Example 8

[0116] This embodiment illustrates profile-adjusting particles prepared using the method of the present invention.

[0117] Profile-adjusting particles were prepared using the same method as in Example 1, except that "0.001M acrylic acid" in Example 1 was changed to "0.003M acrylic acid", and "zirconium acetate" in Example 1 was changed to "zirconium oxychloride".

[0118] The resulting nanogel particles, namely profiled particles, wherein, based on the total structural units of the copolymer, the content of the first structural unit is 57.3 wt%, the content of the second structural unit is 20.9 wt%, and the content of the third structural unit is 21.8 wt%; in addition, based on the total content of the copolymer, the content of the inorganic metal ions is 12.9%.

[0119] Example 9

[0120] This embodiment illustrates profile-adjusting particles prepared using the method of the present invention.

[0121] Profile-modifying particles were prepared using the same method as in Example 5, except that “2-acrylamide-2-methylpropanesulfonic acid 0.001M” in Example 5 was changed to “2-acrylamide-2-methylpropanesulfonic acid 0.002M”.

[0122] The resulting nanogel particles, namely profiled particles, wherein, based on the total structural units of the copolymer, the content of the first structural unit is 53.9 wt%, the content of the second structural unit is 39.3 wt%, and the content of the third structural unit is 6.8 wt%; in addition, based on the total content of the copolymer, the content of the inorganic metal ions is 12.1 wt%.

[0123] Example 10

[0124] Profile-modifying particles were prepared using the same method as in Example 9, except that “2-acrylamide-2-methylpropanesulfonic acid 0.002M” in Example 9 was changed to “2-acrylamide-2-methylpropanesulfonic acid 0.003M”.

[0125] The resulting nanogel particles, namely profiled particles, wherein, based on the total structural units of the copolymer, the content of the first structural unit is 45 wt%, the content of the second structural unit is 49.3 wt%, and the content of the third structural unit is 5.7 wt%; in addition, based on the total content of the copolymer, the content of the inorganic metal ions is 10.2 wt%.

[0126] By comparing with Example 1 Figure 1 and Figure 2 It can be seen that the prepared profile control particles can reach the nanoscale in size, and the minimum energy is less than 100 nm, which can solve the problem of "injection failure" of profile control particles, meet the injection requirements of profile control particles in deep reservoirs, and at the same time, prepare nanoparticles with core-shell structure in one step.

[0127] By comparing Comparative Example 1, Examples 2 to 6, and... Figure 3 and Figure 4 It can be seen that increasing the content of zirconium metal complex ions slightly weakens the expansion properties of the gel, but significantly enhances the mechanical strength. The mechanical strength is highest when the zirconium concentration is 0.0004M, and the mechanical strength can reach 0.51MPa when the expansion ratio is 46. However, further increasing the zirconium content leads to a decrease in mechanical strength.

[0128] By comparing Examples 5, 7, and 8, and... Figure 5 and Figure 6 It can be seen that increasing the acrylic acid content of the complexing monomer can enhance the complexing effect between the systems, and the mechanical strength of the gel is significantly improved. After seven days of expansion (expansion ratio of 15.7), the mechanical strength can reach up to 0.89 MPa. However, the expansion performance is significantly weakened. Therefore, in order to ensure the expansion performance during application, it is necessary to carefully increase the complexing effect in the system.

[0129] By comparing Examples 6, 9, and 10, and... Figure 7 and Figure 8 It can be seen that increasing the content of the charged monomer 2-acrylamide-2-methylpropanesulfonic acid can significantly enhance the swelling performance of the gel system, with a swelling ratio of up to 115. However, at ultra-high swelling ratios, the mechanical strength is also correspondingly weakened.

[0130] The results above show that the present invention connects hydrophilic framework monomers, highly water-absorbent charged monomers, and supramolecular complex monomers through free radical reactions to form copolymers via covalent bonds. At the same time, metal ions are added to form physical crosslinks through metal supramolecular complexation. The swelling and mechanical strength can be adjusted by regulating the composition of different monomers, thereby achieving the preparation of particles that have both swelling and mechanical strength. These particles have good formation shear resistance and solve the problem that traditional profile control particles have weak mechanical strength or even breakage after expansion.

[0131] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. The application of profile-modifying particles as profile control agents in oil reservoirs, characterized in that, The profile-adjusting particles comprise a copolymer and inorganic metal ions complexed on the copolymer, wherein the content of the inorganic metal ions is 3.8-18.9 wt%, based on the total content of the copolymer; wherein the copolymer comprises a first structural unit provided by a skeleton monomer, a second structural unit provided by a charged monomer, a third structural unit provided by a complexing monomer, and a crosslinking agent; the inorganic metal ion is a zirconium ion, and the salt containing the inorganic metal ion is selected from one or more of zirconium oxychloride, zirconium acetate, zirconium sulfate, zirconium chloride, zirconium silicate, and zirconium hydroxide; wherein the skeleton monomer is acrylamide; the charged monomer comprises one or more of 2-acrylamido-2-methylpropanesulfonic acid, sodium p-styrenesulfonate, (3-acrylamidopropyl)trimethylammonium chloride, and acryloyloxyethyltrimethylammonium chloride; the complexing monomer comprises one or more of acrylic acid, methacrylic acid, maleic acid, itaconic acid, and aconitic acid; and the crosslinking agent is N,N-methylenebisacrylamide; Wherein, based on the total structural units of the copolymer, the content of the first structural unit is 30-80 wt%, the content of the second structural unit is 10-50 wt%, and the content of the third structural unit is 1-30 wt%; The profile-adjusting particles have a particle size ≤ 1 μm; the profile-adjusting particles have slow expansion properties and an expansion ratio ≤ 83; and the compressive strength of the profile-adjusting particles after expanding in brine for 7 days is ≤ 0.99 MPa.

2. The application according to claim 1, wherein, Based on the total structural units of the copolymer, the content of the first structural unit is 45-67.1 wt%, the content of the second structural unit is 20.9-49.3 wt%, and the content of the third structural unit is 5.7-21.8 wt%.

3. The application according to claim 1, wherein, The particle size of the profile-adjusting particles is 90-100 nm.

4. The application according to any one of claims 1-3, wherein, The method for preparing the profile-adjusting particles includes: (1) A dispersed phase is prepared by contacting a skeleton monomer, a charged monomer, a complex monomer, a salt containing inorganic metal ions, an initiator, a crosslinking agent and water; (2) A continuous phase is prepared by contacting a surfactant and an organic solvent; (3) Under ultrasonic conditions, the dispersed phase is added to the continuous phase to obtain a water-in-oil emulsion; (4) The water-in-oil emulsion is heated to carry out free radical polymerization reaction, and then washed, centrifuged and dried to obtain profile-adjusting particles.

5. The application according to claim 4, wherein, The quantities of each material, expressed in molar equivalents, include: The skeletal monomer is 0.001-0.1M, the charged monomer is 0.0001-0.1M, the complexing monomer is 0.0001-0.1M, the inorganic metal ion salt is 0.00001-0.001M, and the crosslinking agent is 1×10⁻⁶. -5 M to 1×10 -3 M, the initiator is 1×10 -5 M to 1×10 -3 M.

6. The application according to claim 5, wherein, The skeletal monomer is 0.01-0.1M, the charged monomer is 0.001-0.003M, the complexing monomer is 0.001-0.003M, the inorganic metal ion salt is 0.0002-0.0007M, and the crosslinking agent is 1×10 - 4 M to 1×10 -3 M, the initiator is 1×10 -4 M to 1×10 -3 M.

7. The application according to claim 4, wherein, The organic solvent is selected from one or more of cyclohexane, chloroform, n-hexane, dichloromethane, toluene, and ethyl acetate.

8. The application according to claim 5, wherein, The conditions for the free radical polymerization reaction include: a temperature of 50-80℃ and a time of 60-300 min.

9. The application according to claim 8, wherein, The temperature is 65-75℃, and the time is 80-180 minutes.

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