Plant polyphenol-based high molecular polymer drilling fluid additive, and preparation method and application thereof

Abstract

The present application relates to the technical field of petroleum chemical industry, in particular to a kind of high molecular polymer drilling fluid additive based on plant polyphenol and its preparation method and application, unsaturated olefin with carbon number of 12-20 and unsaturated polar organic compound are used to graft modification to plant polyphenol, and high molecular polymer drilling fluid additive is obtained.The long-chain alkyl group of unsaturated olefin with carbon number of 12-20 can improve the lipophilicity of drilling fluid additive, and then improve the stability of drilling fluid;The polar group of unsaturated polar organic compound can improve the rigidity of molecular main chain, and at the same time help the formation of hydrogen bond, to improve the high temperature resistance, viscosity reduction stability and filtration loss reduction of drilling fluid, so as to meet the needs of deep oil and gas exploitation.At the same time, it can better cater to the development concept of green, environmental protection, high efficiency and harmless.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, and in particular to a polymer drilling fluid additive based on plant polyphenols, its preparation method, and its application. Background Technology

[0002] Drilling fluid additives refer to the chemical agents added during the preparation and treatment of drilling fluids. In recent years, with the increase in oil and gas utilization, the development of oil and gas resources has become more complex, and drilling fluids have increasingly higher performance requirements to adapt to different development environments. Drilling fluid viscosity reducers can reduce the viscosity and shear stress of drilling fluids, effectively regulate the rheological properties of drilling fluids, and maintain various performance characteristics of drilling fluids. They are one of the most important additives in drilling fluids. Early viscosity reducers were mainly iron-chromium lignin sulfonates, but their application was limited because they contained toxic chromium, which is harmful to humans and the environment. Therefore, research began on natural wood-based and tannin-based viscosity reducers in order to replace chromium-containing viscosity reducers, but their temperature resistance was poor and their functions were limited.

[0003] Zhang Jianyun et al. conducted a preliminary study on the properties of Tara sulfonated methyl tannin (SMT-T) prepared by extraction, sulfonation, and complexation of Tara pod shells. The results showed that SMT-T is feasible for use as a drilling mud diluent. SMT-T is chromium-free and has excellent properties such as high temperature resistance and salt resistance. It is suitable for use in deep wells, gas wells, and high-density wells with well temperatures of 180-220℃ (Zhang Jianyun, Li Zhiguo, Wu Hao. Study on the properties of drilling mud diluent Tara sulfonated methyl tannin (SMT-T) [J]. Biomass Chemical Engineering, 2007, 41(3): 21-26.).

[0004] Plant polyphenols are the third largest forest by-product in my country, after hemicellulose, cellulose, and lignin. They are naturally occurring macromolecular compounds with phenolic hydroxyl groups and are widely found in plants. As a rich and renewable green resource, plant polyphenols are poised to become one of the most important resource treasures for humankind as other primary resources are gradually depleted and environmental protection requirements become increasingly stringent. Natural plant polyphenols contain numerous active hydroxyl groups, which can act as adsorption groups for bentonite and as grafting sites for vinyl monomers, exhibiting good biocompatibility and biodegradability. However, their temperature resistance is poor. With increased oil and gas drilling and extraction, deeper oil and gas deposits and higher reservoir temperatures make drilling fluid additives prone to degradation, compromising system stability. Therefore, chemical modification of plant polyphenols is necessary to improve their high-temperature resistance for better application in deep oil and gas extraction. Summary of the Invention

[0005] The purpose of this invention is to provide a high-molecular polymer drilling fluid additive based on plant polyphenols, its preparation method and application. Through graft copolymerization of various modified substances, the emulsification and dispersion effects of plant polyphenols in drilling fluids, as well as their high-temperature resistance, are synergistically improved, thereby meeting the requirements of deep oil and gas extraction.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a polymer drilling fluid additive based on plant polyphenols, wherein plant polyphenols are grafted and modified using unsaturated olefins with 12-20 carbon atoms and unsaturated polar organic compounds to obtain the polymer drilling fluid additive.

[0007] This invention uses natural plant materials as a base and synthesizes green, high-performance drilling fluid additives through chemical modification. It can solve the problem that the monomers of the raw materials for the synthesis of polymer additives in existing drilling fluid treatment agents are mostly toxic and easily leave residues in the product.

[0008] Among them, the long-chain alkyl groups of unsaturated olefins with 12-20 carbon atoms can improve the lipophilicity of drilling fluid additives, giving them better lipophilic effects and improving their emulsification and dispersion effects in oil-based drilling fluids, thereby improving the stability of the drilling fluid and preventing demulsification. The polar groups of unsaturated polar organic compounds can increase the rigidity of the molecular backbone and also facilitate the formation of hydrogen bonds, thereby improving high-temperature resistance and viscosity-reducing stability.

[0009] Furthermore, the plant polyphenol is one or more of tannic acid, gallic acid, and tannin, preferably tannic acid; the pyrogallol of tannic acid can be oxidized to an ortho-quinone structure, and the quinone group has a double bond-like property, which facilitates graft copolymerization with unsaturated olefins and unsaturated polar organic compounds to achieve functional modification.

[0010] Furthermore, the unsaturated polar organic compound includes one or more of unsaturated amides, unsaturated pyrrolidones, and unsaturated acid anhydrides, preferably at least two of them. Unsaturated amides include acrylamide, unsaturated pyrrolidones include N-vinylpyrrolidone, and unsaturated acid anhydrides include maleic anhydride. The unsaturated polar organic compounds can be combined in any way.

[0011] For example, in some specific embodiments, the unsaturated polar organic compound includes acrylamide and N-vinylpyrrolidone, or includes acrylamide and maleic anhydride, or includes N-vinylpyrrolidone and maleic anhydride, or includes acrylamide, N-vinylpyrrolidone and maleic anhydride simultaneously.

[0012] Furthermore, the unsaturated olefin is selected from one or more of dodecene, pentadecene, hexadecene, octadecene, and eicosene, preferably octadecene. The additive obtained from octadecene exhibits the best emulsification stability.

[0013] Furthermore, the grafting modification is carried out under the action of a peroxide initiator. The peroxide initiator can both oxidize the pyrogallol structure of tannic acid to an ortho-quinone structure and initiate a free radical addition reaction.

[0014] Furthermore, the peroxide initiator includes one or more of benzoyl peroxide, benzoyl tert-butyl peroxide, methyl ethyl ketone peroxide, hydrogen peroxide, ammonium persulfate, and potassium persulfate, preferably benzoyl peroxide.

[0015] Furthermore, the mass ratio of the unsaturated olefin to the plant polyphenol is (3-7):1, preferably 5:1; the plant polyphenol is preferably tannic acid.

[0016] Furthermore, the mass ratio of the unsaturated polar organic compound to the plant polyphenol is (1-5):1, preferably (2-3):1.

[0017] Furthermore, the preparation method includes the following steps:

[0018] S1. Add plant polyphenols, unsaturated olefins with 12-20 carbon atoms and unsaturated polar organic compounds to an organic solvent and heat at 60-100℃ for 0.5-2h.

[0019] S2. Dissolve the peroxide initiator in the organic solvent, and then add it dropwise to the solution in step S1. React at a constant temperature for 2-8 hours.

[0020] S3. After the reaction is complete, cool to room temperature, precipitate with methanol, and then separate the solid and liquid to obtain a polymer drilling fluid additive.

[0021] Furthermore, the organic solvent is a mixture of one or more of toluene, benzene, and chloroform;

[0022] Furthermore, the plant polyphenol is tannic acid; the unsaturated olefin is octadecene; and the unsaturated polar organic compound includes at least two of acrylamide, N-vinylpyrrolidone, and maleic anhydride. The mass ratio of octadecene to tannic acid is (3-7):1; the mass ratio of acrylamide to tannic acid is (1-3):1; the mass ratio of N-vinylpyrrolidone to tannic acid is (0.5-1):1; and the mass ratio of maleic anhydride to tannic acid is (0.5-1):1.

[0023] This process, based on the pyrogallol structure of tannic acid, leverages its susceptibility to oxidation into an ortho-quinone structure. Since the quinone group possesses double-bond-like properties, it can polymerize with olefins and amides containing double bonds. Therefore, octadecene, acrylamide, N-vinylpyrrolidone, and maleic anhydride are selected for graft copolymerization to synthesize high-performance drilling fluid additives. Introducing octadecene into the polymer through graft copolymerization, linking it to long-chain alkyl groups, enhances the lipophilicity of the drilling fluid additive, resulting in better lipophilic effects and improved emulsification and dispersion in oil-based drilling fluids. The introduction of highly polar structural units such as acrylamide, N-vinylpyrrolidone, and maleic anhydride is crucial. Acrylamide contains a pyramidal nitrogen atom, increasing the rigidity of the molecular backbone. N-vinylpyrrolidone, with its five-membered ring structure, is a highly polar monomer, similar to maleic anhydride, ensuring hydrogen bond formation.

[0024] Secondly, the present invention provides a high molecular weight polymer drilling fluid additive based on plant polyphenols, which is obtained by any of the preparation methods described above.

[0025] Thirdly, the present invention provides an application of a polymer drilling fluid additive based on plant polyphenols for reducing viscosity and filtration loss in drilling fluids.

[0026] Furthermore, the amount of the polymer drilling fluid additive is 0.5-5% of the mass of the drilling fluid, preferably 1-3%.

[0027] Furthermore, the drilling fluid includes white oil, emulsifier, organic clay, CaCl2 aqueous solution, CaO, filtration loss reducer, and barite.

[0028] Based on 100mL of white oil, the following amounts of each component should be added: emulsifier 8-12g, organic clay 2.8-3.3g, 15-25% CaCl2 aqueous solution 20-30mL, CaO 2-3g, filtration loss reducer 4-6g, and barite 250-300g.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. The polymer drilling fluid additive based on plant polyphenols provided by this invention utilizes the long-chain alkyl groups of unsaturated olefins with 12-20 carbon atoms to improve the oleophilicity of the drilling fluid additive, thereby improving its emulsification and dispersion effect in oil-based drilling fluids and giving the drilling fluid high stability; the polar groups of unsaturated polar organic compounds improve the rigidity of the molecular backbone and help form hydrogen bonds, thereby improving high temperature resistance and viscosity reduction stability.

[0031] 2. This invention is based on inexpensive, readily available, and environmentally friendly raw materials. Through chemical modification, it endows tannic acid with superior properties, enabling it to better meet the market's development concept of "green, environmentally friendly, efficient, and harmless". Attached Figure Description

[0032] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 The infrared spectrum of the plant polyphenol-based polymer drilling fluid additive prepared in Example 1;

[0034] Figure 2 The infrared spectrum of the plant polyphenol-based polymer drilling fluid additive prepared in Example 2 is shown.

[0035] Figure 3 The drilling fluid filter cake is obtained from the plant polyphenol-based polymer drilling fluid additive prepared in Example 2. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] Example 1

[0038] A polymer drilling fluid additive based on plant polyphenols and its preparation method include the following steps:

[0039] (1) Add 7g of tannic acid, 35g of octadecene, 14g of acrylamide and 7g of N-vinylpyrrolidone to 200mL of toluene and stir evenly at 300r / min to obtain a mixed solution.

[0040] (2) Transfer the mixed solution into a three-necked flask and heat it in a water bath at 90°C for 1 hour while stirring constantly.

[0041] (3) Dissolve the initiator benzoyl peroxide (BPO) in toluene and slowly add it dropwise to a three-necked flask. Control the dropping rate, keep the temperature constant for 5 hours, and stir continuously.

[0042] (4) The solution was cooled to room temperature, precipitated with methanol, and dried by filtration to obtain the product.

[0043] (5) The product is ground and pulverized to obtain a plant polyphenol modified polymer drilling fluid additive.

[0044] Figure 1 The infrared spectrum of Example 1 shows that at 2990 cm⁻¹ -1 The absorption peak at 3280 cm⁻¹ is the stretching vibration absorption peak of long-chain alkanes CH, proving the presence of octadecene; -1 The absorption peak at 1830 cm⁻¹ represents the stretching vibration of NH in acrylamide. -1 The absorption peak at 3000 cm⁻¹ corresponds to the stretching vibration of C=O in acid anhydrides, confirming the presence of maleic anhydrides; and the absorption peak at 3000 cm⁻¹ further confirms this. -1 -3100cm -1 The absence of peaks indicates the absence of the characteristic absorption peak of -C=C-, proving that a polymerization reaction has occurred and that all monomers are present.

[0045] Example 2

[0046] A polymer drilling fluid additive based on plant polyphenols and its preparation method include the following steps:

[0047] (1) Add 7g of tannic acid, 35g of octadecene, 14g of acrylamide and 7g of maleic anhydride to 200mL of toluene and stir evenly at 300r / min to obtain a mixed solution.

[0048] (2) Transfer the mixed solution into a three-necked flask and heat it in a water bath at 90°C for 1 hour while stirring constantly.

[0049] (3) Dissolve the initiator benzoyl peroxide (BPO) in toluene and slowly add it dropwise to a three-necked flask. Control the dropping rate, keep the temperature constant for 5 hours, and stir continuously.

[0050] (4) The solution was cooled to room temperature, precipitated with methanol, and dried by filtration to obtain the product.

[0051] (5) The product is ground and pulverized to obtain a plant polyphenol modified polymer drilling fluid additive.

[0052] Figure 2 The infrared spectrum of Example 2 shows that at 2990 cm⁻¹ -1 The absorption peak at 3260 cm⁻¹ is the stretching vibration peak of long-chain alkanes CH, proving the presence of octadecene; -1 The absorption peak at 1480 cm⁻¹ represents the stretching vibration of NH₃ in acrylamide. -1 The absorption peak for stretching vibrations of ketones is at 1380 cm⁻¹. -1The absorption peak at 3000 cm⁻¹ represents the stretching vibration absorption peak of CN in N-vinylpyrrolidone, confirming the presence of N-vinylpyrrolidone; and the absorption peak at 3000 cm⁻¹ further confirms its presence. -1 -3100cm -1 The absence of peaks indicates the absence of the characteristic absorption peak of -C=C-, proving that a polymerization reaction has occurred and that all monomers are present.

[0053] Example 3

[0054] A polymer drilling fluid additive based on plant polyphenols and its preparation method include the following steps:

[0055] (1) Add 7g of tannic acid, 35g of octadecene, 7g of maleic anhydride and 7g of N-vinylpyrrolidone to 200mL of toluene and stir evenly at 300r / min to obtain a mixed solution.

[0056] (2) Transfer the mixed solution into a three-necked flask and heat it in a water bath at 90°C for 1 hour while stirring constantly.

[0057] (3) Dissolve the initiator benzoyl peroxide (BPO) in toluene and slowly add it dropwise to a three-necked flask. Control the dropping rate, keep the temperature constant for 5 hours, and stir continuously.

[0058] (4) The solution was cooled to room temperature, precipitated with methanol, and dried by filtration to obtain the product.

[0059] (5) The product is ground and pulverized to obtain a plant polyphenol modified polymer drilling fluid additive.

[0060] Example 4

[0061] The difference from Example 1 is that N-vinylpyrrolidone was not added.

[0062] Example 5

[0063] The difference from Example 1 is that 7g of maleic anhydride was added.

[0064] Comparative Example 1

[0065] A polymer drilling fluid additive based on plant polyphenols and its preparation method include the following steps:

[0066] (1) Add 7g of tannic acid, 7g of maleic anhydride and 7g of N-vinylpyrrolidone to 200mL of toluene and stir evenly at 300r / min to obtain a mixed solution.

[0067] (2) Transfer the mixed solution into a three-necked flask and heat it in a water bath at 90°C for 1 hour while stirring constantly.

[0068] (3) Dissolve the initiator benzoyl peroxide (BPO) in toluene and slowly add it dropwise to a three-necked flask. Control the dropping rate, keep the temperature constant for 5 hours, and stir continuously.

[0069] (4) The solution was cooled to room temperature, precipitated with methanol, and dried by filtration to obtain the product.

[0070] (5) The product is ground and pulverized to obtain a plant polyphenol modified polymer drilling fluid additive.

[0071] Comparative Example 2

[0072] A plant polyphenol drilling fluid additive and its preparation method, comprising the following steps:

[0073] (1) The tannic acid powder was thoroughly dried to obtain a plant polyphenol drilling fluid additive.

[0074] Test 1: Compatibility Performance Test

[0075] To evaluate the compatibility of drilling fluid additives in oil-based drilling fluids, this study aims to determine whether drilling fluid additives can achieve good dispersion and suspension in oil-based drilling fluids without affecting their rheological properties and stability.

[0076] Preparation of oil-based drilling fluid slurry: Add 240 mL of white oil to a high-speed stirring cup. While stirring at a high speed of 11000 rpm, add in the following order: 24 g of primary emulsifier HT-MUL, 7.5 g of organic clay, 60 mL of 20% CaCl2 aqueous solution, 6 g of CaO, 12 g of filtration reducer, and 650 g of a slurry with a density of 1.8 g / cm³. 3 The barite was stirred for 20 minutes, and then each new treatment agent was added and stirred for 10 minutes until all raw materials were added and stirred together for 40 minutes to obtain the oil-based drilling fluid.

[0077] The prepared drilling fluid samples were tested at room temperature before and after aging (180℃, 16h) using a six-speed viscometer. Stable readings for Φ600, Φ300, Φ200, Φ100, Φ6, and Φ3 were recorded sequentially at different speeds. Apparent viscosity: AV = ηapparent = Φ600 / 2 mPa·s; Plastic viscosity: PV = ηplastic = Φ600 - Φ300 mPa·s; Dynamic shear force: YP = τ0 = (Φ300 - PV) / 2 = Φ300 - Φ600 / 2 Pa; Dynamic-plastic ratio: YP / PV = (Φ300 - Φ600 / 2) / (Φ600 - Φ300).

[0078] The rheological parameters of the drilling fluid were tested in accordance with the national standard GB / T 29170-2012 "Laboratory Testing of Drilling Fluids for Petroleum and Natural Gas Industry", and the results are shown in Table 1.

[0079] Table 1. Rheological and demulsification voltage properties of drilling fluids prepared with additives in Examples 1-5 and Comparative Examples 1-2.

[0080]

[0081] As shown in Table 1, the rheological parameters of the drilling fluid remained essentially unchanged before and after aging after adding the additives prepared in the examples. This indicates that the additives prepared in this invention have excellent temperature resistance and do not adversely affect the rheological properties of the drilling fluid. The viscosity reducer mainly adsorbs on the end faces of clay particles, giving them a certain negative charge, thereby breaking down the network structure. Therefore, the main function of the viscosity reducer is to reduce dynamic shear force (YP). As shown in the table, Examples 1-3 all have a viscosity-reducing effect, with Example 1 showing the best viscosity-reducing effect. Demulsification voltage (ES) is an important reference indicator for the stability of the emulsion system. The higher the demulsification voltage, the more stable the emulsion. The demulsification voltage of water-in-oil emulsion drilling fluid should be above 400V. The demulsification voltages of Examples 1-3 are all above the minimum value and are all better than those of Comparative Examples 1 and 2, indicating that the emulsion systems of the three examples have strong stability.

[0082] Test 2: Static Settlement Stability Test

[0083] Weighting materials are prone to settling under gravity, which can lead to problems such as downhole leakage, stuck pipe, difficulty in well control and cementing operations. Therefore, static settling stability tests are conducted on drilling fluid systems.

[0084] The drilling fluid density was measured using a specially designed drilling fluid hydrometer. During the measurement, the mud cup was first filled with drilling fluid, the measuring cap was placed on top, and any drilling fluid overflowing from the small hole in the measuring cap was wiped clean. The hydrometer's blade was then placed on the cutter head of the base, and the rider was continuously moved until the bubble level was centered between the two lines. The reading on the left side of the rider at this point indicates the density of the drilling fluid being measured, as shown in Table 2.

[0085] Table 2. Settling properties of drilling fluids obtained from Examples 1-5 and Comparative Examples 1-2 after aging with additives.

[0086]

[0087] As shown in Table 2, the static settling factor of the product added to the example is smaller than that of the comparative product, indicating that the density difference of the product added to the example is smaller and it has good settling stability. The comparative product, because it is insoluble in oil-based drilling fluid systems and has demulsified after aging, showed settling at the bottom after standing, with a static settling factor > 52%.

[0088] Test 3: Filtration Loss Measurement

[0089] Static filtration loss was measured using a high-temperature, high-pressure filtration loss meter (model 71, 180℃). The specific testing method involved preheating the heating jacket, pouring the prepared drilling fluid into the drilling fluid cup, adding filter paper, tightening the cup cap, and slowly placing the drilling fluid cup into the heating jacket. The cup was then rotated to lock the buckle. The upper and lower connecting valves were connected and secured with the fixing pins. A pressure of 0.7 MPa was applied. When the temperature reached 180℃, the pressure increased to 4.2 MPa. The bottom valve was opened to collect the filtrate after timing. After the experiment, the valves were closed, the drilling fluid cup was removed, and after sufficient cooling, the filter cake could be removed.

[0090] Table 3. Filtration loss of drilling fluids obtained from additives in Examples 1-5 and Comparative Examples 1-2.

[0091]

[0092] Table 3 shows the filtration loss of drilling fluids obtained from the additives in Examples 1-5 and Comparative Examples 1-2 after 1 hour. The filtration loss in the examples is relatively small, within 56 mL, while the filtration loss in the comparative examples is significantly larger.

[0093] Figure 3 As shown in Example 2, the drilling mud was measured by a high-temperature and high-pressure filtration loss meter, and the filtration loss was 5.6 mL in 1 hour. The resulting filter cake had a smooth, thin and dense surface, with a thickness of about 3 mm, which effectively reduced the filtration loss of the system.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-molecular-weight polymer drilling fluid additive based on plant polyphenols, characterized in that, Plant polyphenols were grafted and modified with unsaturated olefins with 12-20 carbon atoms and unsaturated polar organic compounds to obtain polymer drilling fluid additives. The plant polyphenols are one or more of tannic acid, gallic acid, and tannin; The unsaturated polar organic compounds include one or more of unsaturated amides, unsaturated pyrrolidones, and unsaturated acid anhydrides; The mass ratio of the unsaturated olefin to the plant polyphenol is (3-7):1; And / or, the mass ratio of the unsaturated polar organic compound to the plant polyphenol is (1-5):

1.

2. The preparation method of the polymer drilling fluid additive based on plant polyphenols according to claim 1, characterized in that, The grafting modification was carried out under the action of a peroxide initiator.

3. The method for preparing a polymer drilling fluid additive based on plant polyphenols according to claim 2, characterized in that, The peroxide initiator includes one or more of benzoyl peroxide, benzoyl tert-butyl peroxide, methyl ethyl ketone peroxide, hydrogen peroxide, ammonium persulfate, and potassium persulfate.

4. The method for preparing a plant polyphenol-based polymer drilling fluid additive according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Add plant polyphenols, unsaturated olefins with 12-20 carbon atoms and unsaturated polar organic compounds to an organic solvent and heat at 60-100℃ for 0.5-2h. S2. Dissolve the peroxide initiator in the organic solvent, and then add it dropwise to the solution in step S1. React at a constant temperature for 2-8 hours. S3. After the reaction is complete, cool to room temperature, precipitate with methanol, and then separate the solid and liquid to obtain a polymer drilling fluid additive.

5. The method for preparing a polymer drilling fluid additive based on plant polyphenols according to claim 4, characterized in that, The organic solvent is a mixture of one or more of toluene, benzene, and chloroform. And / or, the plant polyphenol is tannic acid; the unsaturated olefin is octadecene; the unsaturated polar organic compound includes acrylamide, N-vinylpyrrolidone, and maleic anhydride; The mass ratio of octadecene to tannic acid is (3-7):1; the mass ratio of acrylamide to tannic acid is (1-3):1; the mass ratio of N-vinylpyrrolidone to tannic acid is (0.5-1):1; and the mass ratio of maleic anhydride to tannic acid is (0.5-1):

1.

6. A polymeric drilling fluid additive based on plant polyphenols, characterized in that, It is obtained by the preparation method according to any one of claims 1-5.

7. The application of the plant polyphenol-based polymer drilling fluid additive as described in claim 6, characterized in that, Used to reduce viscosity and filtration loss in drilling fluids.

8. The application of the plant polyphenol-based polymer drilling fluid additive according to claim 7, characterized in that, The amount of the polymer drilling fluid additive used is 0.5-5% of the mass of the drilling fluid; And / or, the drilling fluid includes white oil, emulsifier, organocarbon, aqueous CaCl2 solution, CaO, filtration reducer, and barite.

9. The application of the plant polyphenol-based polymer drilling fluid additive according to claim 8, characterized in that, The amount of the polymer drilling fluid additive used is 1-3%.

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