Tannic acid-based hyperbranched nanoparticles, preparation method, and application thereof

Abstract

This invention proposes tannic acid-based hyperbranched nanoparticles, obtained by grafting tannic acid onto an amino-containing compound in the presence of an oxidant. The nanoparticles have a particle size of 90 to 230 nm. The resulting tannic acid-based hyperbranched nanoparticles are used as shale inhibitors in water-based drilling fluids, achieving a cuttings recovery rate of 89.41-94.57% at a concentration of 1% to 2% by mass in the drilling fluid, demonstrating good shale stability.

Description

Technical Field

[0001] The invention belongs to the technical field of high molecular polymers, and particularly relates to tannic acid-based hyperbranched nanoparticles and a preparation method and application thereof. Background Art

[0002] Mud shale formations are characterized by low permeability, high clay matrix content in pores, and the development of micro-nano-scale pores and microcracks. Mud shale is easily hydrated, expanded, and dispersed. Drilling fluid filtrate can easily invade the formation along the shale micropores and microcracks, causing the microcracks to propagate and expand, leading to a series of problems such as well wall instability, mud balling of drill tools, and difficulty in wellbore purification. This increases the difficulty of drilling and affects the exploration and development of shale oil and gas resources.

[0003] Shale inhibitors effectively inhibit hydration, swelling, and dispersion of shale clay, significantly reducing the risk of wellbore instability. The development and utilization of shale inhibitors is a key technology in oil and gas drilling. Currently, various shale inhibitors are available, primarily including inorganic salts, organic ammonium (amine) salts, low-molecular-weight organic amines, high-molecular-weight polymers, and nanoparticles. Shale inhibitors primarily inhibit hydration, swelling, and dispersion of shale by inhibiting clay surface hydration, coating shale particles, modifying shale surface wettability, and controlling the water activity of the drilling fluid.

[0004] Currently, nanoparticle shale inhibitors primarily include inorganic nanoparticles (such as nano-SiO2, TiO2, and CaCO3) and organic polymer microspheres. Inorganic nanoparticles, such as SiO2 nanoparticles, are inexpensive and commonly used to prepare shale inhibitors. However, their high surface activity makes them prone to agglomeration, while their high rigidity makes them susceptible to detachment and migration after entering formation pores, compromising their sealing effectiveness. Therefore, surface modification of the inorganic particles is necessary. Summary of the Invention

[0005] In order to solve the above problems in the prior art, the present invention provides a tannic acid-based hyperbranched nanoparticle and a preparation method and application thereof.

[0006] In a first aspect, the present invention proposes a tannic acid-based hyperbranched nanoparticle, which is obtained by grafting tannic acid onto an amino compound under the action of an oxidant; the nanoparticle has a particle size of 90nm to 230nm; the amino compound contains at least two active amines; the active amines are selected from -NH and -NH2.

[0007] It should be noted that hyperbranched polymers, such as hyperbranched polyetheramines and polyamides, possess highly branched structures, numerous functional groups, nanoscale size, and the ability to interact with clay at multiple sites, effectively stabilizing shale. Their small size allows them to penetrate micro- and nanoscale pores and microcracks in shale, blocking pore throats and providing a physical seal. This prevents or slows the transmission of pore pressure within the shale, effectively improving wellbore stability.

[0008] Tannic acid (TA) is a polyphenolic compound derived from natural plants. It contains abundant benzene rings and phenolic hydroxyl groups. It oxidizes to a quinone-like structure in air and undergoes Michael addition or Schiff base reactions with amino compounds. Simultaneously, it polymerizes, forming nanoparticles through π-π interactions, stacking, and deposition of the benzene rings. If the amino compound used is a hyperbranched polyamine, the resulting polytannic acid (PTA) nanoparticles can be grafted with the hyperbranched polyamine. These PTA nanoparticles are used as shale inhibitors. Their abundant amino groups and catechol hydroxyl groups form multi-site, strong adhesion interactions with clay molecules, effectively inhibiting clay hydration, swelling, and dispersion. The stacked benzene ring structure is hydrophobic, hindering water molecules from entering the clay layer. Furthermore, the nanoparticle structure acts as a physical blocker. In summary, polytannic acid (PTA)-grafted hyperbranched polyamine nanoparticles, prepared by the simple reaction of TA and hyperbranched polyamine under mild conditions, could be an environmentally friendly, biodegradable, and highly effective shale inhibitor.

[0009] As a specific embodiment of the present invention, the amino compound is polyetheramine, polyethylene polyamine or hyperbranched polyamide HBPA.

[0010] As a specific embodiment of the present invention, the polyetheramine includes polyetheramine D230, D400 and T403; and / or,

[0011] The polyethylene polyamines include triethylenetetramine TETA, tetraethylenepentamine TEPA, pentaethylenehexamine PEHA and branched polyethyleneimine PEI.

[0012] In a second aspect, the present invention provides a method for preparing the tannic acid-based hyperbranched nanoparticles, comprising the following steps:

[0013] S1: dissolving tannic acid and an amino compound in a first solvent to obtain a tannic acid solution and an amino compound solution respectively;

[0014] S2: dissolving the oxidant in an acid-base buffer solution to obtain an oxidant solution;

[0015] S3: mixing the tannic acid solution and the amino compound solution obtained in step S1, adding the mixture to the oxidant solution obtained in step S2, reacting, and obtaining tannic acid-based hyperbranched nanoparticles through sedimentation, separation, and drying.

[0016] As a specific embodiment of the present invention, in step S1, the first solvent is ethanol, water, and a mixture of ethanol and water; the volume ratio of ethanol to water in the mixture of ethanol and water is (2-6): (4-8).

[0017] As a specific embodiment of the present invention, in step S2, the oxidant is one of ammonium persulfate ((NH4)2S2O8, sodium periodate (NaIO4), and copper sulfate hydrate (CuSO4·5H2O);

[0018] The acid-base buffer is a Tris-HCl buffer, and the pH value of the buffer is adjusted to 7-8.5;

[0019] As a specific embodiment of the present invention, in step S3, the reaction conditions are room temperature reaction and the reaction time is 2 to 4 hours.

[0020] In a third aspect, the present invention provides applications of the tannic acid-based hyperbranched nanoparticles in the field of shale inhibitors.

[0021] As a specific embodiment of the present invention, the tannic acid-based hyperbranched nanoparticles are added to a water-based drilling fluid as a shale inhibitor; preferably, the mass fraction of the tannic acid-based hyperbranched nanoparticles in the drilling fluid is 1% to 2%.

[0022] The above raw materials in the present invention can be prepared in-house or purchased commercially, and the present invention is not particularly limited thereto.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention utilizes tannic acid (TA), a natural plant polyphenolic compound, and an amino-containing compound to react in a one-step reaction at room temperature to prepare polytannic acid-grafted hyperbranched polyamine nanoparticle shale inhibitors. This method is simple and requires mild conditions. In addition, the resulting particles are rich in catechol hydroxyl groups from tannic acid and amino groups from branched polyamines, which can form multi-site, strong adhesion interactions with clay molecules, effectively inhibiting clay hydration, swelling, and dispersion. The stacked benzene ring structure of polytannic acid is hydrophobic, preventing water molecules from entering the clay layer. The nanoparticle structure can act as a physical plugging agent. The composition and structural characteristics of the tannic acid-based hyperbranched nanoparticles are beneficial to maintaining shale stability.

[0025] 2. The tannic acid-based hyperbranched nanoparticles of the present invention are low in toxicity, environmentally friendly, and degradable. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The molecular structure and abbreviated symbol of tannic acid (TA) in the embodiments of the present invention;

[0027] Figure 2 Schematic diagram of tannic acid oxidation, reaction with amino groups, self-polymerization, and deposition to form polytannic acid-grafted hyperbranched polymer nanoparticles;

[0028] Figure 3 It is the name of the amino compound and its molecular structure. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to specific examples, but they do not constitute any limitation to the present invention.

[0030] In each embodiment of the present invention, the shale inhibition of the obtained nanoparticles was evaluated by Zeta potential test and rock cuttings rolling dispersion experiment, and the specific details are as follows:

[0031] 1% and 2% nanoparticle inhibitors were added to 4% bentonite-based slurry, magnetically stirred for 24 hours, and diluted. The Zeta potential of the experimental slurry was tested using a Zeta potential analyzer at room temperature. Each sample was tested 3 times and the average value was taken.

[0032] Cuttings rolling dispersion experiment: Add 1% or 2% nanoparticle inhibitor to 350 mL of clean water, add 50 g of cuttings with a particle size of 6-10 mesh, age at 100°C for 16 hours, then wash with clean water, pass through a 40-mesh sieve, dry and weigh at 105±3°C, and calculate the cuttings recovery rate.

[0033] Cuttings recovery rate (%) = m1 / 50×100%

[0034] Among them, m1 is the mass of rock chips recovered after hot rolling.

[0035] Example 1

[0036] This embodiment provides a tannic acid-based hyperbranched nanoparticle and a preparation method thereof, the specific details of which are as follows:

[0037] S1: Dissolve 1 g of tannic acid (TA) in 50 mL of ethanol and dissolve 0.5 g of hyperbranched polyamide (HBPA) in 50 mL of ethanol to obtain a tannic acid solution and a hyperbranched polyamide solution;

[0038] S2: Dissolve 0.3 g of sodium periodate (NaIO4) in 10 mL of Tris-HCl buffer, where the pH value of the buffer is 8.5, to obtain an oxidant solution;

[0039] S3: At room temperature, the tannic acid solution and the hyperbranched polyamide solution obtained in step S1 are mixed, and the mixture is added to the oxidant solution obtained in step S2, and the mixture is stirred and reacted for 2 hours. After overnight sedimentation, centrifugal separation, and drying, tannic acid-based hyperbranched nanoparticles are obtained.

[0040] The tannic acid-based hyperbranched nanoparticles obtained in Example 1 had a particle size of 90-110 nm and a zeta potential of 27.2 mV, as observed by SEM. Adding 2% of these particles to a 4% bentonite-based slurry increased the zeta potential of the experimental slurry from -30.91 mV to -15.11 mV. Rock cuttings rolling dispersion experiments showed that the rock cuttings recovery rate without the addition of nanoparticle inhibitors was only 30.5%, while the rock cuttings recovery rate with the addition of 2% nanoparticle inhibitors reached 94.57%, indicating that the prepared nanoparticles have good shale stability.

[0041] Example 2

[0042] This embodiment provides a tannic acid-based hyperbranched nanoparticle and a preparation method thereof, the specific details of which are as follows:

[0043] S1: dissolving 2.5 g of tannic acid (TA) in 100 mL of a mixed solvent of ethanol and water, and dissolving 0.25 g of branched polyethyleneimine (PEI) in 100 mL of a mixed solvent of ethanol and water, wherein the volume ratio of ethanol to water is 1:1; obtaining a tannic acid solution and a branched polyethyleneimine solution;

[0044] S2: Dissolve 1 g of ammonium persulfate ((NH4)2S2O8) in 50 mL of Tris-HCl buffer, where the pH value of the Tris-HCl buffer is 7, to obtain an oxidant solution;

[0045] S3: At room temperature, the tannic acid solution and the branched polyethylenimine solution obtained in step S1 are mixed, and the mixture is added to the oxidant solution obtained in step S2, and the mixture is stirred and reacted for 4 hours. After overnight sedimentation, centrifugal separation, and drying, tannic acid-based hyperbranched nanoparticles are obtained.

[0046] The tannic acid-based hyperbranched nanoparticles obtained in Example 2 had a particle size of 186-230 nm and a zeta potential of 28.45 mV. Adding 1% of these particles to a 4% bentonite-based slurry increased the zeta potential of the experimental slurry from -30.91 mV to -18.23 mV. Rock cuttings rolling dispersion experiments showed that the rock cuttings recovery rate reached 89.41% with the addition of 1% nanoparticle inhibitor, demonstrating good shale stability.

[0047] Example 3

[0048] This embodiment provides a tannic acid-based hyperbranched nanoparticle and a preparation method thereof, the specific details of which are as follows:

[0049] S1: Dissolve 1.5 g of tannic acid (TA) in 100 ml of a mixed solvent of ethanol and water, and dissolve 1.5 g of triethylenetetramine (TETA) in 100 ml of a mixed solvent of ethanol and water, wherein the volume ratio of ethanol to water is 2:8; obtain a tannic acid solution and a triethylenetetramine solution;

[0050] S2: 0.9 g of CuSO4·5H2O and H2O2 were mixed in a molar ratio of 1:1 and dissolved in 30 mL of Tris-HCl buffer, wherein the pH value of the Tris-HCl buffer was 9; to obtain an oxidant solution;

[0051] S3: At room temperature, the tannic acid solution and triethylenetetramine solution obtained in step S1 are mixed, and the mixture is added to the oxidant solution obtained in step S2, and the mixture is stirred and reacted for 4 hours. After overnight sedimentation, centrifugal separation, and drying, tannic acid-based hyperbranched nanoparticles are obtained.

[0052] The tannic acid-based hyperbranched nanoparticles obtained in Example 3 had a particle size of 108-153 nm and a zeta potential of 24.31 mV. After adding 2% of the above-mentioned particles to a 4% prehydrated sodium soil suspension, the zeta potential of the experimental slurry increased from -30.91 mV to -20.78 mV. The rock cuttings rolling dispersion experiment showed that the rock cuttings recovery rate reached 90.25% when 2% of the nanoparticle inhibitor was added, indicating good shale stability.

[0053] Example 4

[0054] This embodiment provides a tannic acid-based hyperbranched nanoparticle and a preparation method thereof, the specific details of which are as follows:

[0055] S1: Dissolve 1 g of tannic acid (TA) in 50 mL of water and 0.5 g of tetraethylenepentamine (TEPA) in 50 mL of water to obtain a tannic acid solution and a tetraethylenepentamine solution;

[0056] S2: Dissolve 0.3 g of sodium periodate (NaIO4) in 20 mL of Tris-HCl buffer, where the pH value of the buffer is 8.5, to obtain an oxidant solution;

[0057] S3: At room temperature, the tannic acid solution and tetraethylenepentamine solution obtained in step S1 are mixed, and the mixture is added to the oxidant solution obtained in step S2, and the mixture is stirred and reacted for 2 hours. After overnight sedimentation, centrifugal separation, and drying, tannic acid-based hyperbranched nanoparticles are obtained.

[0058] The tannic acid-based hyperbranched nanoparticles obtained in Example 4 had a particle size of 93-133 nm and a zeta potential of 24.58 mV. Adding 2% of these particles to a 4% bentonite-based slurry increased the zeta potential of the experimental slurry from -30.91 mV to -19.22 mV. Rock cuttings rolling dispersion experiments showed that the rock cuttings recovery rate reached 92.50% with the addition of 2% nanoparticle inhibitor, indicating good shale stability.

[0059] Example 5

[0060] This embodiment provides a tannic acid-based hyperbranched nanoparticle and a preparation method thereof, the specific details of which are as follows:

[0061] S1: 2.5 g of tannic acid (TA) was dissolved in 100 mL of a mixed solvent of ethanol and water, and 2 g of pentaethylenehexamine (PEHA) was dissolved in 100 mL of a mixed solvent of ethanol and water, wherein the volume ratio of ethanol to water was 1:1, to obtain a tannic acid solution and a pentaethylenehexamine solution;

[0062] S2: Dissolve 0.8 g of sodium periodate (NaIO4) in 30 mL of Tris-HCl buffer, where the pH value of the buffer is 8.5, to obtain an oxidant solvent;

[0063] S3: At room temperature, the tannic acid solution and pentaethylenehexamine solution obtained in step S1 are mixed, and the mixture is added to the oxidant solution obtained in step S2, and the mixture is stirred and reacted for 2 hours. After overnight sedimentation, centrifugal separation, and drying, tannic acid-based hyperbranched nanoparticles are obtained.

[0064] The tannic acid-based hyperbranched nanoparticles obtained in Example 5 had a particle size of 115-154 nm and a zeta potential of 26.87 mV. After adding 2% of the above-mentioned particles to a 4% bentonite-based slurry, the zeta potential of the experimental slurry increased from -30.91 mV to -17.28 mV. The rock cuttings rolling dispersion experiment showed that the rock cuttings recovery rate reached 93.82% when 2% of the nanoparticle inhibitor was added, indicating good shale stability.

[0065] Example 6

[0066] This embodiment provides a tannic acid-based hyperbranched nanoparticle and a preparation method thereof, the specific details of which are as follows:

[0067] S1: 2.5 g of tannic acid (TA) was dissolved in 100 mL of a mixed solvent of ethanol and water, and 0.5 g of polyetheramine (T403) was dissolved in 50 mL of a mixed solvent of ethanol and water, wherein the volume ratio of ethanol to water was 6:4, to obtain a tannic acid solution and a polyetheramine solution;

[0068] S2: Dissolve 0.5 g of sodium periodate (NaIO4) in 20 mL of Tris-HCl buffer, where the pH value of the buffer is 8.5, to obtain an oxidant solution;

[0069] S3: At room temperature, the tannic acid solution and the polyetheramine solution obtained in step S1 are mixed, and the mixture is added to the oxidant solution obtained in step S2, and the mixture is stirred and reacted for 2 hours. After overnight sedimentation, centrifugal separation, and drying, tannic acid-based hyperbranched nanoparticles are obtained.

[0070] The tannic acid-based hyperbranched nanoparticles obtained in Example 6 had a particle size of 93-121 nm and a zeta potential of 25.73 mV. After adding 2% of the above-mentioned particles to a 4% bentonite-based slurry, the zeta potential of the experimental slurry increased from -30.91 mV to -20.43 mV. The rock cuttings rolling dispersion experiment showed that the rock cuttings recovery rate reached 89.60% when 2% of the nanoparticle inhibitor was added, indicating good shale stability.

[0071] Example 7

[0072] This embodiment provides a tannic acid-based hyperbranched nanoparticle and a preparation method thereof, the specific details of which are as follows:

[0073] S1: Dissolve 3 g of tannic acid (TA) in 100 ml of ethanol and dissolve 1 g of polyetheramine (D230) in 100 mL of ethanol to obtain a tannic acid solution and a polyetheramine solution;

[0074] S2: Dissolve 1.2 g of sodium periodate (NaIO4) in 40 mL of Tris-HCl buffer, where the pH value of the buffer is 8.5, to obtain an oxidant solution;

[0075] S3: At room temperature, the tannic acid solution and the polyetheramine solution obtained in step S1 are mixed, and the mixture is added to the oxidant solution obtained in step S2, and the mixture is stirred and reacted for 2 hours. After overnight sedimentation, centrifugal separation, and drying, tannic acid-based hyperbranched nanoparticles are obtained.

[0076] The tannic acid-based hyperbranched nanoparticles obtained in Example 7 had a particle size of 132-141 nm and a zeta potential of 26.06 mV. Adding 2% of these particles to a 4% bentonite-based slurry increased the zeta potential of the experimental slurry from -30.91 mV to -19.98 mV. Rock cuttings rolling dispersion experiments showed that the rock cuttings recovery rate reached 90.32% with the addition of 2% nanoparticle inhibitor, indicating good shale stability.

[0077] Example 8

[0078] This embodiment provides a tannic acid-based hyperbranched nanoparticle and a preparation method thereof, the specific details of which are as follows:

[0079] S1: Dissolve 1.2g of tannic acid (TA) in 100mL of ethanol and 0.3g of polyetheramine (D400) in 100mL of ethanol.

[0080] S2: Dissolve 0.3 mL of sodium periodate (NaIO4) in 20 mL of Tris-HCl buffer, where the pH value of the buffer is 8.5, to obtain an oxidant solution;

[0081] S3: At room temperature, the tannic acid solution and the polyetheramine solution obtained in step S1 are mixed, and the mixture is added to the oxidant solution obtained in step S2, and the mixture is stirred and reacted for 2 hours. After overnight sedimentation, centrifugal separation, and drying, tannic acid-based hyperbranched nanoparticles are obtained.

[0082] The tannic acid-based hyperbranched nanoparticles obtained in Example 8 had a particle size of 153-186 nm and a zeta potential of 25.83 mV. After adding 2% of the above-mentioned particles to a 4% bentonite-based slurry, the zeta potential of the experimental slurry increased from -30.91 mV to -20.35 mV. The rock cuttings rolling dispersion experiment showed that the rock cuttings recovery rate reached 90.32% when 2% of the nanoparticle inhibitor was added, indicating good shale stability.

[0083] Comparative Example 1

[0084] This comparative example provides a nanoparticle and a preparation method thereof, the specific details of which are as follows:

[0085] 1 g of tannic acid (TA) in Example 1 was replaced by 1 g of nano-silicon dioxide (30 nm), and other conditions remained unchanged.

[0086] The nanoparticles obtained in Comparative Example 1 had a particle size of 450 nm and a Zeta potential of 15.83 mV. After adding 2% of the above particles to a 4% bentonite-based slurry, the Zeta potential of the experimental slurry increased from -30.91 mV to -13.35 mV. The rock cuttings rolling dispersion experiment showed that the rock cuttings recovery rate reached 75.21% when 2% nanoparticle inhibitor was added. Compared with Example 1, the nanoparticles obtained were larger and the shale stability was weaker.

[0087] The tannic acid-based hyperbranched nanoparticles obtained in Examples 1-8 were used as shale inhibitors. When 2% of the tannic acid-based hyperbranched nanoparticles were added to the 4% bentonite, the Zeta potential of the experimental slurry increased from -30.91 mV to -15.11 to -20.78 mV, and the rock chip recovery rate reached 89.41 to 94.57%, indicating good shale stability.

[0088] Any numerical value mentioned in the present invention includes all values ​​that increase by one unit each time from the lowest value to the highest value if there is only a gap of two units between any minimum value and any maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is stated to be 50-90, it is meant in this specification to specifically list values ​​such as 51-89, 52-88... and 69-71 and 70-71. For non-integer values, it is appropriate to consider units of 0.1, 0.01, 0.001 or 0.0001. These are just some special examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed lowest value and the listed highest value are considered to have been disclosed.

[0089] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A hyperbranched nanoparticle based on tannic acid, characterized in that, The particles are obtained by grafting tannic acid onto an amino compound under the action of an oxidant; the particle size of the nanoparticles is 90nm to 230nm; The amino-containing compound comprises at least two active amines; the active amines are selected from -NH, -NH2; The amino compound is polyetheramine, polyethylene polyamine or hyperbranched polyamide HBPA; The mass ratio of the tannic acid to the amino compound is (1-10):

1.

2. The tannic acid-based hyperbranched nanoparticles according to claim 1, wherein The polyetheramines include polyetheramine D230, D400 and T403.

3. The tannic acid-based hyperbranched nanoparticles according to claim 1 or 2, characterized in that The polyethylene polyamines include triethylenetetramine TETA, tetraethylenepentamine TEPA, pentaethylenehexamine PEHA and branched polyethyleneimine PEI.

4. A method for preparing hyperbranched nanoparticles based on tannic acid according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: dissolving tannic acid and an amino compound in a first solvent to obtain a tannic acid solution and an amino compound solution respectively; S2: dissolving the oxidant in an acid-base buffer solution to obtain an oxidant solution; S3: mixing the tannic acid solution and the amino compound solution obtained in step S1, adding the oxidant solution obtained in step S2, reacting, and obtaining tannic acid-based hyperbranched nanoparticles through sedimentation, separation, and drying.

5. The preparation method according to claim 4, characterized in that In step S1, the first solvent is ethanol, water, or a mixture of ethanol and water; and / or, the ratio of tannic acid to the first solvent in the tannic acid solution is (0.5-2) g: (50-100) mL; the ratio of the amino compound to the first solvent in the amino compound solution is (0.1-1) g: (20-100) mL; And / or, the mass ratio of the tannic acid to the amino compound is (1-10):

1.

6. The preparation method according to claim 5, characterized in that The volume ratio of ethanol to water in the ethanol-water mixture is (2-6): (4-8).

7. The preparation method according to claim 4, characterized in that In step S2, the oxidant includes one of ammonium persulfate, sodium periodate, and copper sulfate hydrate; And / or, the acid-base buffer is a Tris-HCl buffer, and the pH of the acid-base buffer is 7 to 8.5; and / or, the volume ratio of the total amount of the tannic acid solution and the amino compound-containing solution used in step S3 to the oxidant solution used is (50-100):(5-30); And / or, the mass ratio of the oxidant to tannic acid is (0.1-0.8):

1.

8. The preparation method according to any one of claims 4 to 7, characterized in that In step S3, the reaction conditions include: reaction at room temperature and reaction time of 2 hours to 4 hours.

9. Use of the tannic acid-based hyperbranched nanoparticles according to any one of claims 1 to 3 or the tannic acid-based hyperbranched nanoparticles prepared by the preparation method according to any one of claims 4 to 8 in the field of shale inhibitors.

10. The use according to claim 9, characterized in that The application is to add the tannic acid-based hyperbranched nanoparticles as a shale inhibitor into a water-based drilling fluid.

11. The use according to claim 10, characterized in that The mass fraction of the tannic acid-based hyperbranched nanoparticles in the drilling fluid is 1% to 2%.

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