High-temperature-resistant salt-resistant cross-linked hydrophobic polymer as well as preparation method and application thereof

Abstract

The invention provides a high-temperature-resistant salt-resistant cross-linked hydrophobic polymer, and belongs to the technical field of hydrophobic polymers. The polymer is prepared by carrying out copolymerization on 2-acrylamido-2-methylpropanesulfonic acid, an alkenyl polycyclic monomer, a divinyl monomer and fluorine-containing short carbon chain acrylic ester, the mass ratio of the 2-acrylamido-2-methylpropanesulfonic acid to the alkenyl polycyclic monomer to the divinyl monomer to the fluorine-containing short carbon chain acrylate is 20: (5-8): (0.5-2): (3-5). The molecular structure of the high-temperature-resistant salt-resistant cross-linked hydrophobic polymer contains a vinyl polycyclic structural unit and a fluorine-containing group which can inhibit thermal degradation of acrylamide under a high-temperature condition, and functional groups such as ester and ether which are easy to degrade at a high temperature do not exist in molecules, so that the high-temperature-resistant salt-resistant cross-linked hydrophobic polymer has good temperature resistance; the aqueous solution viscosity can be kept stable for a long time under a high-temperature condition.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrophobic polymers, and in particular relates to a high temperature and salt resistant cross-linked hydrophobic polymer and a preparation method and application thereof. Background Art

[0002] As oil and gas exploration and development gradually develops towards deep formations and offshore, the formations encountered are becoming increasingly complex, such as high temperature, high salt content and salt-gypsum layers. In order to ensure the safety and smooth progress of drilling operations, higher requirements are placed on drilling fluids and treatment agents. Among them, the viscosity enhancer used to adjust the rheological properties of drilling fluids is crucial. Commonly used polymer viscosity enhancers are easily degraded under high temperature conditions, and the viscosity enhancement effect is greatly reduced when drilling into saline formations, which is not conducive to carrying suspended rock cuttings. At present, the drilling fluid viscosity enhancers used in China are mostly modified fibers, modified guar gum, xanthan gum and acrylamide polymers. Although these viscosity enhancers have their own advantages in some aspects, most of them have problems such as insufficient temperature resistance and salt resistance or unclear viscosity enhancement effect. At present, in high-temperature well sections, the main reliance is on imported viscosity enhancer products from abroad. Therefore, it is necessary to develop a drilling fluid viscosity enhancer with good temperature and salt resistance to meet the needs of deep well drilling.

[0003] In the prior art, synthetic polymer thickeners have significantly improved their resistance to temperature and salt due to the introduction of multiple functional groups. For example, patent CN 201010172382.8 discloses a method for preparing a high temperature and salt resistant thickener for drilling fluid, the main components of which are 2-acrylamide-2-methylpropanesulfonic acid, acrylamide and acrylic acid copolymers. At 180°C and in a salt slurry with a content of more than 30%, the rock cutting rolling recovery rate is greater than 90%, but there is no mention of the effect of viscosity increase and filtration loss reduction. Patent CN 201310061721.9 discloses a drilling fluid thickener and a method for preparing the same, the thickener is polymerized from water-soluble monomers and hydrophobic monomers of different ionic types, has good viscosity increase at 260°C, but the drilling fluid shear force is low after high temperature aging, and there is no mention of salt resistance. Patent CN 201610681472.7 discloses a heat-resistant and salt-resistant thickener for drilling fluid, a preparation method and application. It is polymerized by acrylamide, N-vinyl pyrrolidone, and 4-vinyl-1-(3-sulfopropyl) pyridine salt. At 180°C, the viscosity is maintained well in a high-concentration composite brine composed of 3% calcium chloride, 3% magnesium chloride and 5%-20% sodium chloride. US invention patent US7651980B2 discloses a ternary copolymer composed of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N-vinyl pyrrolidone, a preparation method and application thereof. When used as a drilling fluid thickener, the copolymer can withstand a temperature of up to 260°C, but it is limited to the case of freshwater drilling fluid, and does not involve the evaluation of the thickening effect when the content of sodium and calcium salts in the drilling fluid is high. Summary of the invention

[0004] In order to solve the problems in the prior art, the present invention provides a high temperature and salt resistant cross-linked hydrophobic polymer and a preparation method and application. The molecular structure of the high temperature and salt resistant cross-linked hydrophobic polymer of the present invention contains a vinyl polycyclic structural unit and a fluorine-containing group that can inhibit the thermal degradation of acrylamide under high temperature conditions, and there are no ester, ether and other functional groups that are easily degraded at high temperatures in the molecule, so it has good temperature resistance, and the viscosity of its aqueous solution can remain stable for a long time under high temperature conditions.

[0005] According to one aspect of the present invention, a high temperature and salt resistant cross-linked hydrophobic polymer is provided, wherein the polymer is obtained by copolymerizing raw materials including 2-acrylamido-2-methylpropanesulfonic acid (AMPS), alkenyl polycyclic monomers, divinyl monomers and fluorine-containing short carbon chain acrylate;

[0006] The mass ratio of the 2-acrylamide-2-methylpropanesulfonic acid, the alkenyl polycyclic monomer, the divinyl monomer and the fluorine-containing short carbon chain acrylate is 20: (5-8): (0.5-2): (3-5).

[0007] Optionally, the alkenyl polycyclic monomer is selected from any one of 1-vinyl-2-pyrrolidone (N-vinyl pyrrolidone), 5-vinyl-2-pyrrolidone and 4-vinyl pyridine.

[0008] Optionally, the divinyl monomer is selected from any one of divinylbenzene, 2,4-divinylpyridine, divinylbiphenyl and divinyl sulfone.

[0009] Optionally, the fluorine-containing short carbon chain acrylate is selected from any one of trifluoroethyl methacrylate, hexafluorobutyl methacrylate and dodecafluoroheptyl methacrylate.

[0010] Optionally, the number average molecular weight of the polymer is 1.5 to 2.2 million.

[0011] According to another aspect of the present invention, there is provided a method for preparing the above polymer, comprising the following steps:

[0012] (1) preparing an aqueous solution containing 2-acrylamido-2-methylpropanesulfonic acid, an alkenyl polycyclic monomer, a divinyl monomer, a fluorine-containing short carbon chain acrylate, and a surfactant;

[0013] (2) adjusting the pH value of the aqueous solution, introducing nitrogen gas, and keeping the temperature;

[0014] (3) Under the protection of nitrogen atmosphere, add initiator, stir, react, and obtain viscous glue;

[0015] (4) drying the viscous gel, crushing it, and sieving it to obtain the polymer.

[0016] Optionally, in step (2), sodium hydroxide is used to adjust the pH value of the solution to 7-10.

[0017] Optionally, in step (2), the insulation temperature is 10 to 30° C. and the time is 0.5 to 1 h.

[0018] Optionally, in step (3), the stirring speed is 600 r / min to 1200 r / min.

[0019] Optionally, in step (3), the reaction temperature is 50-80°C and the reaction time is 3-8h.

[0020] Optionally, in step (4), the viscous glue is dried at 100° C. to 105° C. until the moisture content is less than 10%.

[0021] Optionally, in step (4), the mesh size after pulverization is 200-400 mesh.

[0022] Optionally, the surfactant is sodium dodecyl sulfate (SDS).

[0023] Optionally, the mass of the surfactant is 0.5 to 2.0 times the mass of the total monomers, and the total monomers include 2-acrylamide-2-methylpropane sulfonic acid, alkenyl polycyclic monomers, divinyl monomers and fluorine-containing short carbon chain acrylates.

[0024] Optionally, the initiator is selected from one of azobisisobutyronitrile and azobisisoheptanenitrile.

[0025] Optionally, the mass of the initiator is 0.3 to 1.0 times the mass of the total monomers, and the total monomers include 2-acrylamide-2-methylpropanesulfonic acid, alkenyl polycyclic monomers, divinyl monomers and fluorine-containing short carbon chain acrylates.

[0026] Optionally, in the aqueous solution, the mass of water is 1.5 to 4 times the mass of total monomers, and the total monomers include 2-acrylamide-2-methylpropane sulfonic acid, alkenyl polycyclic monomers, divinyl monomers and fluorine-containing short carbon chain acrylates.

[0027] According to another aspect of the present invention, there is provided a use of the above-mentioned polymer or the polymer prepared by the above-mentioned preparation method in a viscosity enhancer for drilling fluid.

[0028] In a specific embodiment of the present invention, a method for preparing a high temperature and salt resistant cross-linked hydrophobic polymer comprises the following steps:

[0029] (1) adding deionized water, 2-acrylamido-2-methylpropanesulfonic acid, alkenyl polycyclic monomer, divinyl monomer, fluorine-containing short carbon chain acrylate and sodium dodecyl sulfate into a reaction kettle, stirring evenly to form a solution;

[0030] (2) adjusting the pH value of the solution to 7-10 with sodium hydroxide, introducing nitrogen, and lowering the temperature in the reactor to 10-30° C.;

[0031] (3) After 0.5 to 1 hour, under the protection of nitrogen atmosphere, a certain amount of initiator was added, and the reaction temperature was gradually increased to 50 to 80°C under the condition of stirring speed of 800 r / min, and the reaction was carried out for 5 hours, and then cooled to room temperature to obtain a viscous glue;

[0032] (4) placing the viscous glue in an oven for heating and drying, and then crushing and sieving to obtain the high temperature and salt resistant cross-linked hydrophobic polymer.

[0033] The present invention has the following beneficial effects:

[0034] (1) The high temperature and salt resistant hydrophobic polymer provided by the present invention has good temperature and salt resistance. When the temperature is as high as 200°C, it still has good viscosity increasing performance and can resist 30% NaCl. At the same time, it can effectively reduce the filtration loss of drilling fluid.

[0035] (2) The polymer of the present invention has a CC chain as the main chain, and a cross-linking agent is used to branch or cross-link the molecular chain, so that the viscosity-enhancing agent molecules form branched or bulk polymers with a certain network structure on the secondary structure, thereby enhancing the temperature resistance.

[0036] (3) The sulfonic acid groups on the polymer molecules can not only improve the water solubility of the thickener, but also have a large charge density and strong hydration ability. The special charge distribution structure makes the sulfonic acid groups insensitive to the attack of external cations, thereby enhancing the salt and calcium resistance of the polymer. The amide groups on the molecules can be firmly adsorbed to clay particles through electrostatic attraction and van der Waals forces, effectively improving the thickening effect of the polymer.

[0037] (4) The main chain of the polymer molecule has added benzene rings and polycyclic structures, which enhances the rigidity of the molecule, optimizes the hydrophilic and hydrophobic properties of the molecular chain, regulates the degree of curling and viscosity changes of the polymer molecules at medium and high temperatures, improves the effects of hydrogen bonds and ionic bonds between polymer molecules and between polymer molecules and other substances, and weakens the high-temperature desorption effect of molecules caused by thermal motion. Therefore, the polymer itself has strong resistance to temperature and salt. At the same time, the strong adsorption of the rigid group of the polymer can ensure that the polymer has a good adsorption effect with clay under high temperature conditions, improves its salt resistance, and ensures that the polymer still has a good viscosity effect at high temperatures.

[0038] (5) Fluorinated short-chain acrylates have excellent heat and chemical resistance, extremely low surface energy, excellent hydrophobicity and oleophobicity, and good film-forming ability. Introducing a certain amount of fluorinated short-chain acrylates into polymers can not only improve the rigidity of the molecular chain and have a hydrophobic shielding effect, improve the hydrolysis and degradation resistance of the product, but also improve the film strength of the drilling fluid mud cake, making it have a better hydrophobic and oleophobic effect, and reduce the speed of filtrate invading the formation. DETAILED DESCRIPTION

[0039] The viscosity of the high temperature and salt resistant hydrophobic polymer aqueous solution in the embodiment of the present invention is measured by using the ZNN-D6 electric six-speed rotary viscometer produced by Qingdao Haitongda Special Instrument Factory. The filtration loss is measured by using the SD-3 medium pressure filter loss meter produced by Qingdao Haitongda Special Instrument Factory.

[0040] In each embodiment of the present invention, the specific information of the reagents used is as follows:

[0041] Divinylbenzene was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0042] 2-Acrylamido-2-methylpropanesulfonic acid was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0043] N-vinylpyrrolidone was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0044] 5-vinyl-2-pyrrolidone was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0045] Trifluoroethyl acrylate was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0046] Sodium dodecyl sulfate (SDS) was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0047] N-vinyl caprolactam was purchased from Shanghai Yuanye Biotechnology Co., Ltd.;

[0048] 2,4-Divinylpyridine was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0049] Hexafluorobutyl methacrylate was purchased from Jinan Guochen Taifu Chemical Co., Ltd.;

[0050] Azobis(2-isoheptanonitrile) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0051] Divinylbiphenyl was purchased from Hubei Yongkuo Technology Co., Ltd.;

[0052] Dodecafluoroheptyl methacrylate was purchased from Zhengzhou Alpha Chemical Co., Ltd.;

[0053] Divinyl sulfone was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0054] Trifluoroethyl methacrylate was purchased from Jinan Guochen Taifu Chemical Co., Ltd.

[0055] Example 1

[0056] (1) Add 50 g of deionized water, 20 g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 5 g of N-vinyl pyrrolidone, 0.5 g of divinylbenzene, 3 g of trifluoroethyl methacrylate, and 0.5 g of sodium dodecyl sulfate (SDS) into a reaction kettle and stir well to form a solution.

[0057] (2) The pH value of the solution was adjusted to 7 with sodium hydroxide, and nitrogen was introduced to raise the temperature in the reactor to 30°C.

[0058] (3) After 0.5 hours, 0.3 g of azobisisobutyronitrile was added under nitrogen atmosphere, and the reaction temperature was gradually increased to 50°C with a stirring speed of 600 r / min. The reaction was continued for 3 hours and cooled to room temperature to obtain a viscous gel.

[0059] (4) The viscous glue is placed in an oven at 105° C. for heating and drying, and then crushed to 200 meshes and sieved to obtain the high temperature and salt resistant cross-linked hydrophobic polymer.

[0060] Example 2

[0061] (1) Add 60 g of deionized water, 20 g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 8 g of 5-vinyl-2-pyrrolidone, 1.0 g of 2,4-divinylpyridine, 4 g of hexafluorobutyl methacrylate, and 1.5 g of sodium dodecyl sulfate (SDS) into a reaction kettle and stir well to form a solution.

[0062] (2) The pH value of the solution was adjusted to 8 with sodium hydroxide, and nitrogen was introduced to raise the temperature in the reactor to 20°C.

[0063] (3) After 0.8 hours, 0.8 g of azobisisohexanenitrile was added under nitrogen atmosphere, and the reaction temperature was gradually increased to 60° C. with a stirring speed of 800 r / min. The reaction was continued for 5 hours and cooled to room temperature to obtain a viscous gel.

[0064] (4) The viscous glue is placed in an oven at 105° C. for heating and drying, and then crushed to 300 meshes and sieved to obtain the high temperature and salt resistant cross-linked hydrophobic polymer.

[0065] Example 3

[0066] (1) Add 80 g of deionized water, 20 g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 6 g of N-vinyl pyrrolidone, 1.5 g of divinyl biphenyl, 5 g of dodecafluoroheptyl methacrylate, and 1.0 g of sodium dodecyl sulfate (SDS) into a reaction kettle and stir well to form a solution.

[0067] (2) The pH value of the solution was adjusted to 9 with sodium hydroxide, and nitrogen was introduced to raise the temperature in the reactor to 20°C.

[0068] (3) After 1 hour, 0.5 g of azobisisobutyronitrile was added under nitrogen atmosphere, and the reaction temperature was gradually increased to 80° C. with a stirring speed of 1000 r / min. The reaction was continued for 6 hours and cooled to room temperature to obtain a viscous gel.

[0069] (4) The viscous glue is placed in an oven at 105° C. for heating and drying, and then crushed to 400 meshes and sieved to obtain the high temperature and salt resistant cross-linked hydrophobic polymer.

[0070] Example 4

[0071] (1) Add 100 g of deionized water, 20 g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 7 g of N-vinyl pyrrolidone, 2 g of divinyl sulfone, 4 g of trifluoroethyl methacrylate, and 2 g of sodium dodecyl sulfate (SDS) into a reaction kettle and stir well to form a solution.

[0072] (2) The pH value of the solution was adjusted to 10 with sodium hydroxide, and nitrogen was introduced to reduce the temperature in the reactor to 10°C.

[0073] (3) After 1 hour, 1.0 g of azobisisobutyronitrile was added under nitrogen atmosphere, and the reaction temperature was gradually increased to 70° C. with a stirring speed of 1200 r / min. The reaction was continued for 6 hours and cooled to room temperature to obtain a viscous gel.

[0074] (4) The viscous glue is placed in an oven at 105° C. for heating and drying, and then crushed to 300 meshes and sieved to obtain the high temperature and salt resistant cross-linked hydrophobic polymer.

[0075] Comparative Example 1

[0076] The difference between Comparative Example 1 and Example 2 is that 4 g of hexafluorobutyl methacrylate in step (1) is removed, and other conditions remain unchanged.

[0077] Comparative Example 2

[0078] The difference between Comparative Example 1 and Example 2 is that 1.0 g of 2,4-divinylpyridine in step (1) is removed, and other conditions remain unchanged.

[0079] Comparative Example 3

[0080] The difference between Comparative Example 1 and Example 2 is that the amount of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) in step (1) is increased from 20 g to 50 g, while other conditions remain unchanged.

[0081] Comparative Example 4

[0082] The difference between Comparative Example 1 and Example 2 is that the reaction temperature in step (3) is increased from 60° C. to 90° C., while other conditions remain unchanged.

[0083] Test Case

[0084] The performance of the high temperature and salt resistant hydrophobic polymers prepared in Examples 1 to 4 and Comparative Examples 1 to 4 was evaluated.

[0085] 1. Temperature and NaCl resistance

[0086] The evaluation method for the heat and salt resistance of the polymer in the embodiment of the present invention is as follows: (1) first prepare an aqueous solution containing a sodium chloride concentration of 30%, then add 2% of the copolymer of the present invention and 2% of anhydrous sodium sulfite to the salt solution under stirring, and stir until the copolymer is completely dissolved; (2) use a ZNN-D6 electric six-speed rotary viscometer to measure the viscosity and shear force of the solution at room temperature; after the measurement, transfer the polymer solution to an XGRL-4A high-temperature roller furnace produced by Qingdao Haitongda Special Instrument Factory, age at 200°C for 16 hours, and cool to room temperature after aging; (3) measure the viscosity and shear force of the aged polymer solution at room temperature, compare the changes in the viscosity and shear force of the polymer solution before and after aging, and use the changes in the solution viscosity and shear force as indicators for evaluating the heat and salt resistance of the copolymer.

[0087] Table 1. Changes in polymer properties before and after aging at 200°C in 30% NaCl solution

[0088]

[0089]

[0090] Blank test: Example 2 without adding salt, that is, clean water + 2% copolymer of the present invention + 2% Na2SO3.

[0091] From the data in Table 1, it can be seen that the high temperature and salt resistant hydrophobic polymers prepared in Examples 1 to 4 maintain good viscosity and shear force in 30% NaCl saline solution. After aging at 200°C for 16h, the viscosity and shear force do not change much, indicating that the high temperature and salt resistant hydrophobic polymers provided by the present invention have good heat and salt resistance, and the viscosity and shear of its aqueous solution can remain stable for a long time under high temperature conditions. However, the monomers in Comparative Example 1 lack fluorine-containing short carbon chain acrylates, and the viscosity and shear force decrease significantly after aging, and the temperature resistance is weak. In Comparative Example 2, there is a lack of cross-linking divinyl monomers, and the generated polymer cannot form an uncrosslinked network structure, and the viscosity and shear force are low, and the temperature resistance is poor. The content of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) in Comparative Example 3 is relatively high. Since 2-acrylamide-2-methylpropanesulfonic acid (AMPS) is highly water-soluble and the content is too high, it affects the dispersion of other monomers, making its polymerization reaction insufficient, and the generated product has low viscosity and shear force. In Comparative Example 4, the polymerization reaction temperature was too high, resulting in a violent polymerization reaction, an incomplete network structure, and low product viscosity.

[0092] 2. Filtration reduction performance

[0093] The evaluation method of the polymer fluid loss reduction performance in the embodiment of the present invention is as follows: (1) 2% of the copolymer described in the present invention and 2% of anhydrous sodium sulfite are added to 4% prehydrated bentonite slurry, and stirred until the copolymer is completely dissolved to form a drilling fluid system; (2) The fluid loss of the drilling fluid system is measured using an SD-3 medium-pressure fluid loss meter at room temperature; after the measurement, the drilling fluid system is transferred to an XGRL-4A high-temperature roller furnace produced by Qingdao Haitongda Special Instrument Factory, aged at 200°C for 16 hours, and then returned to room temperature after aging; (3) The fluid loss of the aged drilling fluid system is measured at room temperature, and the changes in the filtrate volume of the drilling fluid system before and after aging are compared, and the change in the filtrate volume is used as an indicator for evaluating the fluid loss reduction performance of the polymer.

[0094] Table 2. Changes in fluid loss properties of polymers in 4% pre-bentonite before and after aging at 200°C

[0095]

[0096]

[0097] Blank test: no polymer added, i.e. 4% pre-bentonite slurry + 1% copolymer of the present invention

[0098] +2%Na2SO3.

[0099] From the data in Table 2, it can be seen that the high temperature and salt-resistant hydrophobic polymers prepared in Examples 1 to 4 can effectively reduce the filtration loss in 4% pre-bentonite slurry. After aging at 200°C for 16 hours, the filtration loss reduction effect is good, indicating that the high temperature and salt-resistant hydrophobic polymers provided by the present invention have good film-forming and plugging properties. The monomer of Comparative Example 1 lacks fluorine-containing short-chain acrylate, and the filtration loss after aging is larger than that of Examples 1 to 4. The filtration loss reduction effect of Comparative Examples 2 to 4 is poor compared with Examples 1 to 4, but is better than that of Comparative Example 1, indicating that the fluorine group can form a hydrophobic and oil-repellent layer on the surface of the mud cake, which is beneficial to reducing filtration loss.

[0100] Any numerical value mentioned in the present invention, if there is only an interval of two units between any minimum value and any maximum value, includes all values ​​from the minimum value to the maximum value each time increasing by one unit. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is declared to be 50-90, in this specification it means that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as a unit. These are just some specially specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0101] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to 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 functions.

Claims

1. A high temperature and salt resistant cross-linked hydrophobic polymer, characterized in that: The polymer is obtained by copolymerizing raw materials including 2-acrylamide-2-methylpropanesulfonic acid, alkenyl polycyclic monomers, divinyl monomers and fluorine-containing short carbon chain acrylate; The mass ratio of the 2-acrylamide-2-methylpropanesulfonic acid, the alkenyl polycyclic monomer, the divinyl monomer and the fluorine-containing short carbon chain acrylate is 20: (5-8): (0.5-2): (3-5).

2. The polymer according to claim 1, characterized in that The alkenyl polycyclic monomer is selected from any one of 1-vinyl-2-pyrrolidone, 5-vinyl-2-pyrrolidone and 4-vinylpyridine; And / or, the divinyl monomer is selected from any one of divinylbenzene, 2,4-divinylpyridine, divinylbiphenyl and divinylsulfone; And / or, the fluorine-containing short carbon chain acrylate is selected from any one of trifluoroethyl methacrylate, hexafluorobutyl methacrylate and dodecafluoroheptyl methacrylate; And / or, the number average molecular weight of the polymer is 1.5 to 2.2 million.

3. A method for preparing the polymer according to claim 1 or 2, characterized in that: The following steps are involved: (1) preparing an aqueous solution containing 2-acrylamido-2-methylpropanesulfonic acid, an alkenyl polycyclic monomer, a divinyl monomer, a fluorine-containing short carbon chain acrylate, and a surfactant; (2) adjusting the pH value of the aqueous solution, introducing nitrogen gas, and keeping the temperature; (3) Under the protection of nitrogen atmosphere, add initiator, stir, react, and obtain viscous glue; (4) drying the viscous gel, crushing it, and sieving it to obtain the polymer.

4. The preparation method according to claim 3, characterized in that: In step (2), the pH value of the solution is adjusted to 7-10 using sodium hydroxide; And / or, in step (2), the insulation temperature is 10-30° C. and the time is 0.5-1 h.

5. The preparation method according to claim 3 or 4, characterized in that: In step (3), the stirring speed is 600 r / min to 1200 r / min; And / or, in step (3), the reaction temperature is 50-80° C. and the reaction time is 3-8 hours.

6. The preparation method according to any one of claims 3 to 5, characterized in that: In step (4), the viscous glue is dried at 100° C. to 105° C. until the moisture content is less than 10%; And / or, in step (4), the mesh size after pulverization is 200-400 mesh.

7. The preparation method according to any one of claims 3 to 6, characterized in that The surfactant is sodium lauryl sulfate; And / or, the mass of the surfactant is 0.5 to 2.0 times the mass of the total monomers, and the total monomers include 2-acrylamide-2-methylpropane sulfonic acid, alkenyl polycyclic monomers, divinyl monomers and fluorine-containing short carbon chain acrylates.

8. The preparation method according to any one of claims 3 to 7, characterized in that The initiator is selected from one of azobisisobutyronitrile and azobisisoheptanenitrile; And / or, the mass of the initiator is 0.3 to 1.0 times the mass of the total monomers, and the total monomers include 2-acrylamide-2-methylpropane sulfonic acid, alkenyl polycyclic monomers, divinyl monomers and fluorine-containing short carbon chain acrylates.

9. The preparation method according to any one of claims 3 to 8, characterized in that In the aqueous solution, the mass of water is 1.5 to 4 times the mass of total monomers, and the total monomers include 2-acrylamide-2-methylpropane sulfonic acid, alkenyl polycyclic monomers, divinyl monomers and fluorine-containing short carbon chain acrylate.

10. Use of the polymer according to claim 1 or 2, or the polymer prepared by the preparation method according to any one of claims 3 to 9, in a viscosity enhancer for drilling fluid.

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