Hyperbranched polymer modified natural polysaccharide coating inhibitor and preparation method and application thereof

Abstract

The application provides a hyperbranched polymer modified natural polysaccharide coating inhibitor and a preparation method and application thereof, and the coating inhibitor is obtained by mixing modified natural polysaccharide and hyperbranched polyamine after being dissolved in proportion, wherein the modified natural polysaccharide is 50-60 parts by mass, and the hyperbranched polyamine is 40-50 parts by mass, with the sum of the parts by mass being 100; and the concentration of the modified natural polysaccharide and the hyperbranched polyamine after being dissolved is 200-300 g / L. The prepared hyperbranched polymer modified natural polysaccharide coating inhibitor has high coating capacity, significant inhibition capacity and excellent temperature resistance, and the preparation process of the coating inhibitor is simple, which is beneficial to industrial production, is convenient for on-site preparation of drilling fluid, and can achieve good coating and inhibition effect.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling engineering technology, and particularly to the field of water-based drilling fluid treatment agents. Specifically, it relates to hyperbranched polymer-modified natural polysaccharide-coated inhibitors, their preparation methods, and applications. Background Technology

[0002] To ensure the inhibitory performance of water-based drilling fluids during drilling in water-sensitive formations, the commonly used method is to add sufficient amounts of inhibitors and coating inhibitors. The main types are inorganic salts (such as potassium chloride) and organic salts (such as potassium formate). These stabilize the shale by compressing the thickness of the diffuse double layer on the shale surface and reducing the zeta potential. However, in some water-sensitive formations with high salinity, the inhibitory effect of traditional inorganic salt inhibitors may be significantly reduced, failing to effectively meet the inhibition performance requirements during drilling. Asphalt-based inhibitors prevent the permeate of filtrate into the formation through a slurry-like action and can also block formation microfractures, preventing drilling fluid and filtrate from seeping through these fractures, thus effectively preventing well collapse and protecting the oil layer. Potassium salts and high-valence salts of humic acids, as well as organosilicon compounds, can also be used as shale inhibitors. Cationic surfactants and cationic polymers primarily stabilize shale by adsorbing the cationic components of the active part onto the shale surface, neutralizing the negative charge of the shale surface, and making the shale surface oleophilic. However, some products have poor biodegradability, failing to meet increasingly stringent environmental requirements, thus limiting their use in areas with high environmental standards. Polyols exhibit a "cloud point" effect; these precipitated polyols exceeding their cloud point exhibit certain oleophilic characteristics, adhering to the shale surface and forming "emulsions." These "microdroplets" can block small pores within the filter cake and also seal shale pores, reducing shale-water contact and stabilizing the shale. However, their "cloud point" effect is significantly affected by environmental factors such as temperature. Under frequent temperature fluctuations or extreme temperature conditions, their precipitation and oleophilic characteristics may be unstable, affecting their shale stabilization effect and limiting their application in formation drilling under complex temperature environments. High-molecular-weight potassium polyacrylamide (KPAM) combines flocculation and coating with filtration loss reduction. Furthermore, due to the presence of potassium ions, it also inhibits the hydration and swelling of mudstone and shale. The relative molecular mass of zwitterionic polymer FA367 can reach over 1 million. Its main functions are to inhibit drill cuttings dispersion, increase drilling fluid viscosity, and reduce filtration loss. Summary of the Invention

[0003] The purpose of this invention is to address at least one of the aforementioned deficiencies in the prior art. For example, one objective of this invention is to provide a method for preparing a hyperbranched polymer-modified natural polysaccharide-coated inhibitor; a second objective of this invention is to provide a hyperbranched polymer-modified natural polysaccharide-coated inhibitor; and a third objective of this invention is to provide applications of the hyperbranched polymer-modified natural polysaccharide-coated inhibitor.

[0004] To achieve the above objectives, the present invention provides a method for preparing a hyperbranched polymer-modified natural polysaccharide-coated inhibitor.

[0005] The coating inhibitor is obtained by dissolving modified natural polysaccharide and hyperbranched polyamine and mixing them in a certain proportion. The modified natural polysaccharide is 50-60 parts by mass and the hyperbranched polyamine is 40-50 parts by mass, with a total mass of 100 parts. The concentration of the modified natural polysaccharide and the hyperbranched polyamine is 200 g / L to 300 g / L.

[0006] Alternatively, the modified natural polysaccharide can be prepared by dissolving the natural polysaccharide in water, adding sodium periodate of equal mass to the natural polysaccharide, reacting in the dark for 6-10 hours, precipitating in anhydrous ethanol, extracting the solid, and then drying in a vacuum oven to obtain the modified natural polysaccharide.

[0007] The concentration of the natural polysaccharide is 20 g / L to 50 g / L, the drying temperature is 50 to 80°C, and the drying time is 24 to 30 h.

[0008] Alternatively, the natural polysaccharide may include one or more of water-soluble natural polysaccharides such as oxidized sodium alginate, carboxymethyl chitosan, and xanthan gum.

[0009] Alternatively, the hyperbranched polyamine is obtained from a polyamine compound and a polyene compound via a Michael addition reaction.

[0010] Alternatively, the polyamine compound may include one of polyethylene polyamine, a polymer having two terminal amine groups, tris(2-aminoethyl)amine, or 1,8-diamino-3,6-dioxane.

[0011] Alternatively, the polyethylene polyamine includes one of tetraethylenepentamine, diethylenetriamine, and triethylenetetraamine; the polymer having two terminal amine groups includes polyetheramine (PEA).

[0012] Alternatively, the polyene compound may include one of methylene bisacrylamide, poly(ethylene glycol) diacrylate, and trimethylolpropane triacrylate.

[0013] Alternatively, the Michael addition reaction is as follows:

[0014] The polyene compound is prepared into a polyene monomer solution; the polyamine compound is prepared into a polyamine monomer solution;

[0015] The polyamine monomer solution was slowly added to the polyene monomer solution, and then reacted at 60℃~80℃ for 6h~12h. The solvent was then removed and the mixture was dried to obtain the hyperbranched polyamine.

[0016] Alternatively, if the polyene compound is trimethylolpropane triacrylate, the polyene compound is prepared into a polyene monomer solution using a mixed solution; if the polyene compound is methylenebisacrylamide or poly(ethylene glycol) diacrylate, the polyene compound is prepared into a polyene monomer solution using water.

[0017] When the polyamine compound is 1,8-diamino-3,6-dioxaoctane, the polyamine compound is prepared into a polyamine monomer solution using a mixed solution; when the polyamine compound is polyethylenepolyamine, tris(2-aminoethyl)amine or polyetheramine PEA, the polyamine compound is prepared into a polyamine monomer solution using water.

[0018] The mixed solution is prepared by dimethyl sulfoxide and water at a volume ratio of 0.7 to 1.3:1, or by N,N-dimethylformamide and water at a volume ratio of 0.9 to 1.1:1, with a solute concentration of 150 g / L to 250 g / L and an amino group to double bond molar ratio of 1.05 to 1.15:1.

[0019] Another aspect of the present invention provides a hyperbranched polymer-modified natural polysaccharide coating inhibitor.

[0020] The coating inhibitor can be prepared by the above method.

[0021] In another aspect, this invention provides the application of hyperbranched polymer-modified natural polysaccharide-coated inhibitors.

[0022] The hyperbranched polymer-modified natural polysaccharide-coated inhibitor can be applied in the field of water-based drilling fluid treatment agents.

[0023] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0024] (1) The hyperbranched polymer-modified natural polysaccharide coating inhibitor prepared in this invention can increase the liquid phase viscosity of drilling fluid to a certain extent, thereby improving the ability to coat and carry drill cuttings, that is, it has a high-efficiency coating ability.

[0025] (2) The hyperbranched polymer-modified natural polysaccharide-coated inhibitor prepared in this invention exhibits hyperbranched characteristics in some molecular structures, providing a large number of primary amine groups in a certain space, thus having significant inhibitory ability.

[0026] (3) The hyperbranched polymer-modified natural polysaccharide-coated inhibitor prepared in this invention exhibits a hyperbranched structure, which gives it excellent temperature resistance, up to 180℃. Detailed Implementation

[0027] The hyperbranched polymer-modified natural polysaccharide coating inhibitor, its preparation method, and its applications will be described in detail below with reference to exemplary embodiments.

[0028] Exemplary Example 1

[0029] This exemplary embodiment provides a method for preparing a hyperbranched polymer-modified natural polysaccharide-coated inhibitor.

[0030] The coating inhibitor is obtained by dissolving modified natural polysaccharide and hyperbranched polyamine and mixing them in a certain proportion. The modified natural polysaccharide is 50-60 parts by mass and the hyperbranched polyamine is 40-50 parts by mass, with a total mass of 100 parts. The concentration of the modified natural polysaccharide and the hyperbranched polyamine is 200 g / L to 300 g / L.

[0031] In this embodiment, the modified natural polysaccharide is composed of one or more of water-soluble natural polysaccharides such as oxidized sodium alginate, carboxymethyl chitosan, and xanthan gum.

[0032] In this embodiment, the modified natural polysaccharide is prepared by dissolving the natural polysaccharide in water, adding sodium periodate of the same mass as the natural polysaccharide, reacting in the dark for 6 to 10 hours, precipitating in anhydrous ethanol, extracting the solid, and then drying in a vacuum oven to obtain the modified natural polysaccharide.

[0033] The concentration of the natural polysaccharide is 20 g / L to 50 g / L, the drying temperature is 50 to 80°C, and the drying time is 24 to 30 h.

[0034] In this embodiment, the natural polysaccharide includes one or more of water-soluble natural polysaccharides such as oxidized sodium alginate, carboxymethyl chitosan, and xanthan gum.

[0035] In this embodiment, the hyperbranched polyamine is obtained by a Michael addition reaction of a polyamine compound and a polyene compound.

[0036] In this embodiment, the polyamine compound includes one of polyethylene polyamine, polymers having two terminal amine groups, tris(2-aminoethyl)amine, or 1,8-diamino-3,6-dioxane.

[0037] In this embodiment, the polyethylene polyamine includes one of tetraethylenepentamine, diethylenetriamine, and triethylenetetraamine; the polymer having two terminal amine groups includes polyetheramine (PEA).

[0038] In this embodiment, the polyene compound includes one of methylene bisacrylamide, poly(ethylene glycol) diacrylate, and trimethylolpropane triacrylate.

[0039] The Michael addition reaction is as follows:

[0040] The polyene compound is prepared into a polyene monomer solution; the polyamine compound is prepared into a polyamine monomer solution;

[0041] The polyamine monomer solution was slowly added to the polyene monomer solution, and then reacted at 60℃~80℃ for 6h~12h. The solvent was then removed and the mixture was dried to obtain the hyperbranched polyamine.

[0042] In this embodiment, when the polyene compound is trimethylolpropane triacrylate, the polyene compound is prepared into a polyene monomer solution using a mixed solution; when the polyene compound is methylenebisacrylamide or poly(ethylene glycol) diacrylate, the polyene compound is prepared into a polyene monomer solution using water.

[0043] In this embodiment, when the polyamine compound is 1,8-diamino-3,6-dioxaoctane, the polyamine compound is prepared into a polyamine monomer solution using a mixed solution; when the polyamine compound is polyethylene polyamine, tris(2-aminoethyl)amine or polyetheramine PEA, the polyamine compound is prepared into a polyamine monomer solution using water.

[0044] In this embodiment, the mixed solution is prepared by dimethyl sulfoxide and water at a volume ratio of 0.7 to 1.3:1, or by N,N-dimethylformamide and water at a volume ratio of 0.9 to 1.1:1. The solute concentration in the mixed solution is 150 g / L to 250 g / L, and the molar ratio of amine groups to double bonds is 1.05 to 1.15:1.

[0045] Exemplary Example 2

[0046] This exemplary embodiment provides a method for preparing a hyperbranched polymer-modified natural polysaccharide-coated inhibitor.

[0047] This exemplary embodiment utilizes a solution modification method to oxidize and degrade natural polysaccharides, appropriately reducing their molecular weight while introducing aldehyde functional groups into the polysaccharide molecular structure. Then, a hyperbranched polyamine is prepared through an addition reaction of polyamine and polyene monomers. These two components are then compounded in a specific ratio and subjected to a chemical reaction under certain conditions to develop a hyperbranched polymer-modified natural polysaccharide coating inhibitor for water-based drilling fluids, forming a hyperbranched polymer-modified natural polysaccharide complex coating inhibition technology.

[0048] The coating inhibitor is composed of modified natural polysaccharides and hyperbranched polyamines. The mass percentage of each component in the active ingredient of the coating inhibitor is: 50%–60% modified natural polysaccharides and 40%–50% hyperbranched polyamines. The modified natural polysaccharide in the coating inhibitor is composed of one or more water-soluble natural polysaccharides such as oxidized sodium alginate, carboxymethyl chitosan, and xanthan gum (the natural polysaccharide is dissolved in water at a concentration of 20 g / L to 50 g / L, then an equal mass of sodium periodate is added, the reaction is carried out in the dark for 6 to 10 hours, precipitation is obtained in anhydrous ethanol, the solid is obtained by filtration, and the solid is dried in a vacuum oven at 60°C for 24 hours); hyperbranched polyamines are obtained by polyamine compounds (such as tetraethylenepentamine, diethylenetriamine, and triethylenetetramine; or polyetheramines such as PEA with two terminal amine groups; or tris(2-aminoethyl)amine; 1,8-diamino-3,6-dioxane) and polyene compounds (such as methylenebisacrylamide, poly(ethylene glycol) diacrylate, and trimethylolpropane triacrylate) through a Michael addition reaction (the polyene compound is dissolved in water, if the polyene compound is Trimethylolpropane triacrylate is dissolved in a mixed solution prepared by a 1:1 volume ratio of dimethyl sulfoxide and water or N,N-dimethylformamide and water, with a concentration of 150 g / L to 250 g / L. The polyamine compound is then dissolved in water. If the polyamine compound is 1,8-diamino-3,6-dioxane, it is dissolved in a mixed solution prepared by a 1:1 volume ratio of dimethyl sulfoxide and water or N,N-dimethylformamide and water, with a concentration of 150 g / L to 250 g / L and a molar ratio of amine to double bond of 1.1:1. The polyamine monomer solution is added dropwise to the polyene monomer solution under stirring. The reaction time is 6 h to 12 h, and the temperature is 60 °C to 80 °C. After the reaction is complete, the mixture is rotary evaporated at 80 °C and then vacuum dried at 80 °C to constant weight. The two products are then dissolved and mixed in a certain mass ratio (the concentration of the two products is 200g / L to 300g / L) to obtain a hyperbranched polymer-modified natural polysaccharide complex coating inhibitor.

[0049] Exemplary Example 3

[0050] This exemplary embodiment provides a hyperbranched polymer-modified natural polysaccharide-coated inhibitor.

[0051] The coating inhibitor can be prepared by the method described in Exemplary Example 1 or Exemplary Example 2 above.

[0052] Exemplary Example 4

[0053] This exemplary embodiment provides the application of hyperbranched polymer-modified natural polysaccharide-coated inhibitors.

[0054] The coating inhibitor is the hyperbranched polymer-modified natural polysaccharide coating inhibitor described in Exemplary Example 3, which can be applied in the field of water-based drilling fluid treatment agents.

[0055] To better understand the exemplary embodiments described above, further explanation is provided below with reference to specific examples.

[0056] Example 1

[0057] The coating inhibitor components are: 60% modified natural polysaccharide, wherein the modified natural polysaccharide is sodium alginate oxide (sodium alginate is dissolved in water to a concentration of 25 g / L, and then sodium periodate of the same mass as sodium alginate is added, reacted in the dark for 7 h, precipitated in anhydrous ethanol, filtered to obtain a solid, and dried in a vacuum oven at 60 °C for 24 h), and 40% hyperbranched polyamine (trimethylolpropane triacrylate (0.6 mol, 177.6 g) is dissolved in 800 mL of a mixed solution, which is prepared by dimethyl sulfoxide and water in a volume ratio of 1:1; then tetraethylenepentamine (0.99 mol, 187 g) is dissolved in water and added dropwise to the trimethylolpropane triacrylate solution under stirring, the reaction time is 12 h, and the temperature is 70 °C. After the reaction is completed, the solvent is rotary evaporated at 80 °C and then vacuum dried at 80 °C to constant weight). The modified natural polysaccharide and hyperbranched polyamine are prepared into 300 g / L solutions and then mixed to obtain a hyperbranched polymer-modified natural polysaccharide complex coating inhibitor.

[0058] Example 2

[0059] The coating inhibitor components are: 55% modified natural polysaccharide, wherein the modified natural polysaccharide is oxidized carboxymethyl chitosan (carboxymethyl chitosan is dissolved in water at a concentration of 20 g / L, and then sodium periodate of the same mass as carboxymethyl chitosan is added, the reaction is carried out in the dark for 8 h, precipitated in anhydrous ethanol, filtered to obtain a solid, and dried in a vacuum oven at 60 °C for 24 h), and 45% hyperbranched polyamine (polyethylene glycol diacrylate (molecular weight 200, 0.6 mol, 120 g) is dissolved in 500 mL of water; then tris(2-aminoethyl)amine (0.44 mol, 64 g) is dissolved in 300 mL of water, and added dropwise to the polyethylene glycol diacrylate solution under stirring, the reaction time is 8 h, the temperature is 60 °C. After the reaction is completed, the solvent is evaporated by rotary evaporation at 80 °C and then dried under vacuum at 80 °C to constant weight). The modified natural polysaccharide and hyperbranched polyamine are prepared into 300 g / L solutions and then mixed to obtain a hyperbranched polymer-modified natural polysaccharide complex coating inhibitor.

[0060] Example 3

[0061] The coating inhibitor components are: 50% modified natural polysaccharide, wherein the modified natural polysaccharide is oxidized xanthan gum (xanthan gum is dissolved in water at a concentration of 23 g / L, and then sodium periodate of equal mass to xanthan gum is added, reacted in the dark for 9 h, precipitated in anhydrous ethanol, filtered to obtain a solid, and dried in a vacuum oven at 60 °C for 24 h), and 50% hyperbranched polyamine (methylenebisacrylamide (0.5 mol, 77 g) is dissolved in 280 mL of water; then 1,8-diamino-3,6-dioxaoctane (0.55 mol, 81.4 g) is dissolved in 300 mL of a mixed solution, which is prepared by N,N-dimethylformamide and water in a volume ratio of 1:1, and added dropwise to the methylenebisacrylamide solution under stirring, the reaction time is 11 h, the temperature is 75 °C. After the reaction is completed, the solvent is rotary evaporated at 80 °C and then vacuum dried at 80 °C to constant weight). The modified natural polysaccharide and hyperbranched polyamine are prepared into 300 g / L solutions and then mixed to obtain a hyperbranched polymer-modified natural polysaccharide complex coating inhibitor.

[0062] Example 4

[0063] The core swelling reduction rate of the coating inhibitors provided in Examples 1-3 of this invention was tested using the following method: 2g (accurate to 0.01g) of a sample dried at 105℃±3℃ for 4 hours was weighed into a beaker, and 200mL of distilled water was added. The mixture was stirred on an electromagnetic stirrer until completely dissolved. 10g (accurate to 0.01g) of calcium bentonite dried at 110℃±3℃ for 4 hours was weighed and placed into a testing cylinder. The stopper rod was inserted into the cylinder, and the pressure was maintained at 4MPa for 5 minutes to obtain the test core. The testing cylinder containing the core was installed on a shale swelling tester. Distilled water was injected into the cylinder, and the core was soaked for 8 hours. The linear swelling of the core was recorded. The linear swelling of the core should be ≥8mm; otherwise, the bentonite used to prepare the core should be adjusted or replaced. The linear swelling of the core was calculated using the following formula.

[0064]

[0065] In the formula:

[0066] B represents the reduction rate of core swelling, %; ΔH2 represents the linear swelling of the test core after soaking in the sample solution for 8 hours, mm; ΔH1 represents the linear swelling of the test core after soaking in distilled water for 8 hours, mm.

[0067] The experimental test results are shown in Table 1.

[0068] Table 1. Test results of the core swelling reduction rate of the coating inhibitors provided in Examples 1-3 of this invention.

[0069]

[0070] As shown in Table 1, the core swelling reduction rate of the coating inhibitor provided in the examples of the present invention is greater than 70%, indicating that the coating inhibitor can effectively suppress formation hydration dispersion.

[0071] Example 5

[0072] The primary and secondary rolling recoveries of the coated inhibitors provided in Examples 1-3 of this invention were tested as follows: 3.50 g (accurate to 0.01 g) of sample was accurately weighed into a beaker containing 350 mL of distilled water and dissolved by stirring on a magnetic stirrer. 50.0 g of 6-10 mesh rock fragments (Sichuan red soil) was dried at 105℃±3℃ for 8 h. The sample solution and rock fragment particles were added to an aging reactor and rolled at 180℃ for 16 h. After removal and cooling to room temperature, the mixture in the reactor was poured into a 40 mesh sieve, rinsed with clean water, and the rock fragments in the sieve were dried at 105℃±3℃ for 8 h. The weight of the rock fragments was measured (denoted as M). The primary rolling recovery was calculated using the following formula:

[0073]

[0074] In the formula:

[0075] S represents the rolling recovery rate, %; M represents the weight of the recovered rock chips after drying, g.

[0076] The drill cuttings obtained from the first rolling were subjected to a second rolling recovery experiment following the steps described above. The second rolling recovery rate was calculated by the ratio of the obtained drill cuttings mass to the initial drill cuttings mass.

[0077] The experimental test results are shown in Table 2.

[0078] Table 2 shows the rolling recovery rate test results of the coated inhibitors provided in Examples 1-3 of this invention.

[0079] Serial Number One-time rolling recovery rate / % Secondary rolling recovery rate / % Example 1 89 82 Example 2 88 83 Example 3 85 81

[0080] As shown in Table 2, the coating inhibitor provided in this invention has a primary and secondary rolling recovery rate of more than 80%, and exhibits significant high-temperature coating performance.

[0081] Example 6

[0082] The ability of the coated inhibitors provided in Examples 1-3 of this invention to inhibit bentonite dispersion was tested using the following method: Two high-speed stirring cups were taken, and 400 mL of distilled water and 1.00 g (weighed to 0.01 g) of anhydrous sodium carbonate were added to each cup. Under high-speed stirring, 16.0 g (weighed to 0.01 g) of bentonite for drilling fluid test slurry preparation was slowly added to prevent clumping. High-speed stirring was continued for a total of 20 minutes, with at least two stops to scrape off the bentonite adhering to the cup wall. The mixture was then sealed and cured at 25℃±1℃ for 24 hours to obtain a water-based slurry. The above-prepared water-based slurry was then slowly mixed with 4.00 g (weighed to 0.01 g) of sample under high-speed stirring for a total of 20 minutes, with at least two stops to scrape off the sample adhering to the cup wall. The mixture was then sealed and cured at 25℃±1℃ for 3 hours to obtain a coated inhibitor-based slurry. Transfer the two prepared polymer-based slurries to an aging tank, place them in a roller furnace, and hot-roll at 180℃ for 16 hours. After cooling to room temperature, transfer them to a high-speed stirring cup and stir at high speed for 5 minutes. Measure the viscometer reading at 600 r / min according to GB / T 16783.1. Collect the polymer-based slurry after high-temperature rolling into a clean high-speed stirring cup. While stirring, add 16.0 g (weighed to the nearest 0.01 g) of bentonite for drilling fluid test slurry preparation, continue stirring for 10 minutes, and cure in a sealed container at 25℃±1℃ for 3 hours. Transfer the slurry to an aging tank, place it in a roller furnace, and hot-roll at 180℃ for 16 hours. After cooling to room temperature, transfer it to a high-speed stirring cup and stir at high speed for 5 minutes. Measure the viscometer reading at 600 r / min according to GB / T 16783.1. Calculate the apparent viscosity increase rate using the following formula:

[0083]

[0084] In the formula: V is the apparent viscosity increase rate, %; R 600 The reading of the viscometer at 600 r / min after high-temperature hot rolling of the inhibitor-coated slurry; R' 600 The reading of the viscometer at 600 r / min was obtained after adding bentonite to the drilling fluid test slurry and hot rolling it at high temperature.

[0085] The experimental test results are shown in Table 3.

[0086] Table 3. Test results of apparent viscosity increase rate of the coated inhibitors provided in Examples 1-3 of this invention.

[0087] Serial Number Apparent viscosity increase rate / % Example 1 81 Example 2 88 Example 3 86

[0088] As shown in Table 3, the apparent viscosity increase rate of the coating inhibitors provided in the examples of the present invention is less than 90%, indicating that the coating inhibitors have excellent ability to inhibit bentonite hydration and pulping.

[0089] Example 7

[0090] Clay interlayer spacing experiment: 4g of sodium bentonite was dispersed in 100mL of deionized water and magnetically stirred for 24h to ensure complete hydration and prepare a sodium bentonite dispersion. Then, coating inhibitors of different mass fractions were added to the sodium bentonite dispersion, and magnetic stirring was continued for another 24h to ensure full interaction. The sample was centrifuged at 8000r / min for 10min, the precipitate was collected, and the interlayer spacing of the wet sample was determined using X-ray diffraction. The results are shown in Table 4.

[0091] Table 4. Test results of the effect of the coating inhibitor on the clay layer spacing provided in Examples 1-3 of this invention.

[0092]

[0093] Sodium bentonite adsorbs a large number of water molecules during hydration because sodium ions typically exist as hydrated ions between clay layers, increasing the interlayer spacing. However, with the addition of a coating inhibitor, the interlayer spacing gradually decreases as the mass fraction of the inhibitor increases, with the change becoming less pronounced after reaching 1%. This coating inhibitor reduces the interlayer spacing from 1.95 nm to 1.18 nm, indicating its ability to penetrate the clay interlayers and displace hydrated cations, thus reducing the interlayer spacing. Therefore, this coating inhibitor effectively inhibits the hydration of shale and mudstone by displacing the water molecules adsorbed during clay hydration.

[0094] Although the present invention has been described above in conjunction with exemplary embodiments, it should be clear to those skilled in the art that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for preparing a hyperbranched polymer-modified natural polysaccharide-coated inhibitor, characterized in that, The coating inhibitor is obtained by dissolving and mixing modified natural polysaccharides and hyperbranched polyamines in a certain proportion, wherein, Based on a total mass fraction of 100 parts, the modified natural polysaccharide comprises 50-60 parts by mass, and the hyperbranched polyamine comprises 40-50 parts by mass. The concentration of the modified natural polysaccharide and the hyperbranched polyamine dissolved is 200 g / L to 300 g / L.

2. The method for preparing the coated inhibitor according to claim 1, characterized in that, The modified natural polysaccharide is prepared by dissolving the natural polysaccharide in water, adding sodium periodate of the same mass as the natural polysaccharide, reacting in the dark for 6 to 10 hours, precipitating in anhydrous ethanol, extracting the solid, and then drying in a vacuum oven to obtain the modified natural polysaccharide.

3. The method for preparing the coating inhibitor according to claim 2, wherein the natural polysaccharide includes one or more of water-soluble natural polysaccharides such as oxidized sodium alginate, carboxymethyl chitosan, and xanthan gum.

4. The method for preparing the coated inhibitor according to claim 2, characterized in that, The concentration of the natural polysaccharide is 20 g / L to 50 g / L, the drying temperature is 50 to 80°C, and the drying time is 24 to 30 hours.

5. The method for preparing the coated inhibitor according to claim 1, characterized in that, The hyperbranched polyamine is obtained by Michael addition reaction of polyamine and polyene compounds.

6. The method for preparing the coated inhibitor according to claim 5, characterized in that, The polyamine compound includes one of polyethylene polyamine, polymers having two terminal amine groups, tris(2-aminoethyl)amine, and 1,8-diamino-3,6-dioxane.

7. The method for preparing the coated inhibitor according to claim 6, characterized in that, The polyethylene polyamine includes one of tetraethylenepentamine, diethylenetriamine, and triethylenetetraamine; the polymer having two terminal amine groups includes polyetheramine (PEA).

8. The method for preparing the coated inhibitor according to claim 5, characterized in that, The polyene compound includes one of methylene bisacrylamide, poly(ethylene glycol) diacrylate, and trimethylolpropane triacrylate.

9. The method for preparing the coated inhibitor according to claim 5, characterized in that, The Michael addition reaction is as follows: The polyene compound is prepared into a polyene monomer solution; the polyamine compound is prepared into a polyamine monomer solution; The polyamine monomer solution was slowly added to the polyene monomer solution, and then reacted at 60℃~80℃ for 6h~12h. The solvent was then removed and the mixture was dried to obtain the hyperbranched polyamine.

10. The method for preparing the coated inhibitor according to claim 9, characterized in that, When the polyene compound is trimethylolpropane triacrylate, the polyene compound is prepared into a polyene monomer solution using a mixed solution; when the polyene compound is methylenebisacrylamide or poly(ethylene glycol) diacrylate, the polyene compound is prepared into a polyene monomer solution using water. When the polyamine compound is 1,8-diamino-3,6-dioxaoctane, the polyamine compound is prepared into a polyamine monomer solution using a mixed solution; when the polyamine compound is polyethylenepolyamine, tris(2-aminoethyl)amine or polyetheramine PEA, the polyamine compound is prepared into a polyamine monomer solution using water. The mixed solution is prepared by dimethyl sulfoxide and water at a volume ratio of 0.7 to 1.3:1, or by N,N-dimethylformamide and water at a volume ratio of 0.9 to 1.1:1, with a solute concentration of 150 g / L to 250 g / L and an amino group to double bond molar ratio of 1.05 to 1.15:

1.

11. A hyperbranched polymer-modified natural polysaccharide-coated inhibitor, characterized in that, The coating inhibitor can be prepared by the method described in any one of claims 1-10.

12. The application of the hyperbranched polymer-modified natural polysaccharide-coated inhibitor as described in claim 11 in the field of water-based drilling fluid treatment agents.

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