Natural gas hydrate kinetic inhibitor containing a polynuclear structure and a method for preparing the same

Abstract

The present application relates to natural gas hydrate inhibitor technical field, it is a kind of natural gas hydrate dynamics inhibitor containing polycyclic structure and its preparation method, the former raw material includes acryloyl morpholine, maleic anhydride, dimethylaminopropyl acrylamide, isohexyl glycol, initiator, chain transfer agent and chain terminator, obtain as follows: acryloyl morpholine, maleic anhydride and dimethylaminopropyl acrylamide are dissolved in isohexyl glycol solution, occur radical polymerization under the action of initiator, chain transfer agent and chain terminator and get it.In the natural gas injection and gathering and transportation process, add the natural gas hydrate dynamics inhibitor containing polycyclic structure of the present application, it can participate in hydrate crystal structure generation through the unique polycyclic ring, effectively inhibit the growth of hydrate crystal, prevent the generation of large particle hydrate, with the advantages of good inhibiting effect, less dosage, low comprehensive cost.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas hydrate inhibitors, in particular to a natural gas hydrate kinetic inhibitor containing a polycyclic structure and a preparation method thereof. Background Art

[0002] During the injection, production and gathering process of natural gas, low molecular weight hydrocarbons, gases such as hydrogen sulfide and carbon dioxide, and water in the pipeline will form hydrates under certain temperature and pressure conditions. At the very least, this will reduce the gas channel, and at worst, it will cause pipeline or equipment blockage, seriously restricting the development of oilfield gas reservoirs, the application of miscible drive and the construction of gas storage facilities, and affecting safe production.

[0003] Currently, methods for preventing hydrate formation are primarily categorized as physical and chemical. Physical methods primarily eliminate the thermodynamic conditions for hydrate formation in the oil and gas system, and include water removal, heating, pressure reduction, and a combination of these methods. Chemical methods, which alter the system's phase equilibrium, crystal nucleation, crystal growth, or aggregation properties by adding chemical reagents, offer advantages such as simplicity, cost-effectiveness, and high effectiveness, making them the most widely used method for preventing hydrate formation.

[0004] Hydrate inhibitors primarily include traditional thermodynamic inhibitors and conventional kinetic inhibitors. Thermodynamic inhibitors can alter the thermodynamic conditions for natural gas hydrate formation, lowering the equilibrium temperature and increasing the equilibrium pressure, thereby inhibiting hydrate formation. However, these inhibitors require high dosages (a certain mass fraction is required to achieve the desired inhibitory effect), are difficult to recover and recycle, and are expensive to use. Furthermore, some thermodynamic inhibitors are toxic. Conventional kinetic hydrate inhibitors inhibit hydrate nucleation or hinder the growth of crystal nuclei through the action of their functional groups. They offer the advantages of high inhibitory efficacy, low dosage, and economical and environmentally friendly use.

[0005] Conventional kinetic hydrate inhibitors have received widespread attention in recent years. These inhibitors inhibit hydrate nucleation or hinder the growth of crystal nuclei through the action of their functional groups. Their inhibitory effect is significant at low dosages, but at higher supercooling levels, their inhibition time becomes very short, limiting their scope of application.

[0006] To improve hydrate inhibition and maximum supercooling, Chinese patent publication CN111349194A discloses a fluorinated polyvinyl pyrrolidone natural gas hydrate inhibitor and its preparation method. This inhibitor is synthesized from vinyl pyrrolidone and perfluoroalkyl acrylate monomers. However, the high cost of perfluoroalkyl acrylate monomers makes the inhibitor expensive. Chinese patent publication CN109764241A discloses a composite hydrate kinetic inhibitor based on a vinyl imidazole copolymer and its application. This composite hydrate kinetic inhibitor has a maximum supercooling of 12.8°C, but the high dosage (2%) required for the treatment agent increases costs.

[0007] Therefore, existing kinetic hydrate inhibitors have problems such as large dosage, poor inhibition effect, high overall cost and unsuitability for higher supercooling conditions. Summary of the Invention

[0008] The present invention provides a natural gas hydrate kinetic inhibitor containing a polycyclic structure and a preparation method thereof, which overcomes the above-mentioned deficiencies of the prior art and can effectively solve the problems of some kinetic hydrate inhibitors such as large dosage, poor inhibition effect, high overall cost and unsuitability for higher supercooling conditions.

[0009] One of the technical solutions of the present invention is achieved by the following measures: a natural gas hydrate kinetic inhibitor containing a polycyclic structure, the structural formula of which is:

[0010]

[0011] Here, x is 6 to 12, y is 4 to 16, and z is 4 to 8.

[0012] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions:

[0013] The above-mentioned natural gas hydrate kinetic inhibitor containing a polycyclic structure comprises, by weight, 20 to 60 parts of acryloylmorpholine, 10 to 40 parts of maleic anhydride, 30 to 60 parts of dimethylaminopropyl acrylamide, 60 to 120 parts of isohexanediol, 0.1 to 2 parts of initiator, 0.1 to 0.5 parts of chain transfer agent, and 0.1 to 0.5 parts of chain terminator.

[0014] The initiator is a mixture of hydrogen peroxide and vitamin C or azobisisobutyronitrile, wherein the mass ratio of hydrogen peroxide to vitamin C in the mixture of hydrogen peroxide and vitamin C is 1 to 2:1.

[0015] The chain transfer agent is one of dodecyl mercaptan and thioglycolic acid.

[0016] The chain terminator is one of hydroquinone, p-tert-butylcatechol and acetone thiosemicarbazone.

[0017] The above-mentioned natural gas hydrate kinetic inhibitor containing a polycyclic structure is obtained by the following method:

[0018] S1, adding required amounts of maleic anhydride, acryloylmorpholine, and dimethylaminopropylacrylamide to a required amount of isohexylene glycol in sequence under stirring to obtain a mixed solution;

[0019] S2, adding a required amount of initiator to the mixed solution to react to obtain an intermediate product 1;

[0020] S3, adding a required amount of chain transfer agent to the intermediate product 1 and continuing the reaction to obtain the intermediate product 2;

[0021] S4, adding a required amount of chain terminator to the intermediate product 2 and reacting again to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

[0022] In the above step S2, the reaction temperature is 40°C to 80°C, and the reaction time is 0.5h to 1.0h.

[0023] In the above step S3, the reaction time is 2 h to 8 h, and in step S4, the reaction time is 0.5 h to 2.0 h.

[0024] The second technical solution of the present invention is achieved by the following measures: a method for preparing a natural gas hydrate kinetic inhibitor containing a polycyclic structure is carried out as follows:

[0025] S1, adding required amounts of maleic anhydride, acryloylmorpholine, and dimethylaminopropylacrylamide to a required amount of isohexylene glycol in sequence under stirring to obtain a mixed solution;

[0026] S2, adding a required amount of initiator to the mixed solution to react to obtain an intermediate product 1;

[0027] S3, adding a required amount of chain transfer agent to the intermediate product 1 and continuing the reaction to obtain the intermediate product 2;

[0028] S4, adding a required amount of chain terminator to the intermediate product 2 and reacting again to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

[0029] The natural gas hydrate kinetic inhibitor containing a polycyclic structure of the present invention is a kinetic inhibitor. When added during the natural gas injection, production, gathering and transportation process, the natural gas hydrate kinetic inhibitor containing a polycyclic structure of the present invention can participate in the formation of the hydrate crystal structure through its unique polycyclic rings, effectively inhibit the growth of hydrate crystals, and prevent the formation of large-particle hydrates. It has the advantages of good inhibitory effect, small dosage, and low overall cost. At the same time, it can expand the applicable range of supercooling. DETAILED DESCRIPTION

[0030] The present invention is not limited to the following embodiments, and specific implementation methods can be determined based on the technical solutions of the present invention and actual conditions. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all chemical reagents and chemicals commonly known in the prior art; unless otherwise specified, the percentages in the present invention are all percentages by mass; unless otherwise specified, the solutions in the present invention are all aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous hydrochloric acid solution; normal temperature and room temperature in the present invention generally refer to temperatures between 15°C and 25°C, and are generally defined as 25°C.

[0031] The present invention will be further described below in conjunction with the embodiments:

[0032] Example 1: The natural gas hydrate kinetic inhibitor containing a polycyclic structure has the structural formula:

[0033]

[0034] Here, x is 6 to 12, y is 4 to 16, and z is 4 to 8.

[0035] Example 2: The natural gas hydrate kinetic inhibitor containing a polycyclic structure, the raw materials of which include, by weight, 20 to 60 parts of acryloylmorpholine, 10 to 40 parts of maleic anhydride, 30 to 60 parts of dimethylaminopropyl acrylamide, 60 to 120 parts of isohexanediol, 0.1 to 2 parts of initiator, 0.1 to 0.5 parts of chain transfer agent and 0.1 to 0.5 parts of chain terminator.

[0036] Example 3: As an optimization of the above example, the initiator is a mixture of hydrogen peroxide and vitamin C or azobisisobutyronitrile, wherein the mass ratio of hydrogen peroxide to vitamin C in the mixture of hydrogen peroxide and vitamin C is 1 to 2:1.

[0037] Example 4: As an optimization of the above example, the chain transfer agent is one of dodecyl mercaptan and thioglycolic acid.

[0038] Example 5: As an optimization of the above example, the chain terminator is one of hydroquinone, p-tert-butylcatechol and acetone thiosemicarbazone.

[0039] Example 6: As an optimization of the above example, a natural gas hydrate kinetic inhibitor containing a polycyclic structure is obtained by the following method:

[0040] S1, adding required amounts of maleic anhydride, acryloylmorpholine, and dimethylaminopropylacrylamide to a required amount of isohexylene glycol in sequence under stirring to obtain a mixed solution;

[0041] S2, adding a required amount of initiator to the mixed solution to react to obtain an intermediate product 1;

[0042] S3, adding a required amount of chain transfer agent to the intermediate product 1 and continuing the reaction to obtain the intermediate product 2;

[0043] S4, adding a required amount of chain terminator to the intermediate product 2 and reacting again to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

[0044] Example 7: As an optimization of the above example, in step S2, the reaction temperature is 40°C to 80°C, and the reaction time is 0.5h to 1.0h.

[0045] Example 8: As an optimization of the above example, in step S3, the reaction time is 2 h to 8 h, and in step S4, the reaction time is 0.5 h to 2.0 h.

[0046] Example 9:

[0047] The natural gas hydrate kinetic inhibitor containing a polycyclic structure comprises, by weight, 20 parts of acryloylmorpholine, 10 parts of maleic anhydride, 30 parts of dimethylaminopropyl acrylamide, 60 parts of isohexanediol, 0.1 part of an initiator (azobisisobutyronitrile), 0.1 part of a chain transfer agent (dodecyl mercaptan), and 0.1 part of a chain terminator (hydroquinone), and is prepared by the following method:

[0048] S1, adding required amounts of maleic anhydride, acryloylmorpholine, and dimethylaminopropylacrylamide to a required amount of isohexylene glycol in sequence under stirring to obtain a mixed solution;

[0049] S2, add the required amount of initiator to the mixed solution, react at 40°C for 0.5h to obtain intermediate product 1;

[0050] S3, adding a required amount of chain transfer agent to the intermediate product 1 and continuing the reaction for 2 hours to obtain the intermediate product 2;

[0051] S4, adding a required amount of chain terminator to the intermediate product 2 and reacting again for 0.5 h to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

[0052] Example 10:

[0053] The natural gas hydrate kinetic inhibitor containing a polycyclic structure comprises, by weight, 60 parts of acryloylmorpholine, 40 parts of maleic anhydride, 60 parts of dimethylaminopropyl acrylamide, 120 parts of isohexyl glycol, 2 parts of an initiator (a mixture of hydrogen peroxide and vitamin C in a mass ratio of 1:1), 0.5 parts of a chain transfer agent (thioglycolic acid), and 0.5 parts of a chain terminator (p-tert-butylcatechol), and is prepared by the following method:

[0054] S1, adding required amounts of maleic anhydride, acryloylmorpholine, and dimethylaminopropylacrylamide to a required amount of isohexylene glycol in sequence under stirring to obtain a mixed solution;

[0055] S2, add the required amount of initiator to the mixed solution, react at 80°C for 1.0h to obtain intermediate product 1;

[0056] S3, adding a required amount of chain transfer agent to the intermediate product 1 and continuing the reaction for 8 hours to obtain the intermediate product 2;

[0057] S4, adding a required amount of chain terminator to the intermediate product 2 and reacting again for 2.0 hours to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

[0058] Example 11:

[0059] The natural gas hydrate kinetic inhibitor containing a polycyclic structure comprises, by weight, 40 parts of acryloylmorpholine, 20 parts of maleic anhydride, 45 parts of dimethylaminopropyl acrylamide, 80 parts of isohexanediol, 1 part of an initiator (azobisisobutyronitrile), 0.3 parts of a chain transfer agent (dodecyl mercaptan), and 0.3 parts of a chain terminator (acetone thiosemicarbazone), and is prepared by the following method:

[0060] S1, adding required amounts of maleic anhydride, acryloylmorpholine, and dimethylaminopropylacrylamide to a required amount of isohexylene glycol in sequence under stirring to obtain a mixed solution;

[0061] S2, add the required amount of initiator to the mixed solution, react at 60°C for 0.8h to obtain intermediate product 1;

[0062] S3, adding a required amount of chain transfer agent to the intermediate product 1 and continuing the reaction for 6 hours to obtain the intermediate product 2;

[0063] S4, adding a required amount of chain terminator to the intermediate product 2 and reacting again for 1 hour to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

[0064] Compared with the prior art, the present invention has the following beneficial effects:

[0065] The natural gas hydrate kinetic inhibitor containing a polycyclic structure of the present invention is a kinetic inhibitor. When added during the natural gas injection, production, gathering and transportation process, the natural gas hydrate kinetic inhibitor containing a polycyclic structure of the present invention can participate in the formation of the hydrate crystal structure through its unique polycyclic rings, effectively inhibit the growth of hydrate crystals, and prevent the formation of large-particle hydrates. It has the advantages of good inhibitory effect, small dosage, and low overall cost. At the same time, it can expand the applicable range of supercooling.

[0066] Example 12:

[0067] The natural gas hydrate kinetic inhibitor containing a polycyclic structure is obtained by the following method:

[0068] S1, under stirring, add 10 g of maleic anhydride to 90 g of isohexylene glycol, stir and dissolve, then add 40 g of acryloylmorpholine and 40 g of dimethylaminopropyl acrylamide to obtain a mixed solution;

[0069] S2, 1 g of initiator (azobisisobutyronitrile) was added dropwise to the mixed solution, and the mixture was reacted at 70°C for 0.5 h to obtain intermediate product 1;

[0070] S3, adding 0.5 g of chain transfer agent (dodecyl mercaptan) to the intermediate product 1 and continuing the reaction for 5 h to obtain the intermediate product 2;

[0071] S4, adding 0.2 g of a chain terminator (p-tert-butylcatechol) to the intermediate product 2 and reacting again for 1 hour to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

[0072] Example 13:

[0073] The natural gas hydrate kinetic inhibitor containing a polycyclic structure is obtained by the following method:

[0074] S1, under stirring, add 20 g of maleic anhydride to 90 g of isohexylene glycol, stir and dissolve, then add 40 g of acryloylmorpholine and 30 g of dimethylaminopropyl acrylamide to obtain a mixed solution;

[0075] S2, 1 g of initiator (0.5 g of hydrogen peroxide and 0.5 g of vitamin C) was added dropwise to the mixed solution, and the mixture was reacted at 60°C for 0.5 h to obtain intermediate product 1;

[0076] S3, adding 0.5 g of chain transfer agent (thioglycolic acid) to the intermediate product 1 and continuing the reaction for 3 h to obtain the intermediate product 2;

[0077] S4, adding 0.2 g of a chain terminator (acetone thiosemicarbazone) to the intermediate product 2 and reacting again for 1 h to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

[0078] Example 14:

[0079] The natural gas hydrate kinetic inhibitor containing a polycyclic structure is obtained by the following method:

[0080] S1, under stirring, add 20 g of maleic anhydride to 120 g of isohexylene glycol, stir and dissolve, then add 50 g of acryloylmorpholine and 50 g of dimethylaminopropyl acrylamide to obtain a mixed solution;

[0081] S2, 1 g of initiator (0.5 g of hydrogen peroxide and 0.5 g of vitamin C) was added dropwise to the mixed solution, and the mixture was reacted at 80°C for 0.5 h to obtain intermediate product 1;

[0082] S3, adding 1 g of chain transfer agent (dodecyl mercaptan) to the intermediate product 1 and continuing the reaction for 6 h to obtain the intermediate product 2;

[0083] S4, adding 0.3 g of chain terminator (hydroquinone) to the intermediate product 2 and reacting again for 2 h to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

[0084] Example 15: A low-temperature autoclave apparatus was used to evaluate the inhibitory effect of the natural gas hydrate kinetic inhibitor containing a polycyclic structure of the present invention. The inhibitory effect indicators included inhibition time (min) and maximum supercooling (°C). The test method is as follows:

[0085] Inhibition time: First, the reactor was cleaned with distilled water and the cleaning liquid was discharged. Then, a 0.5% concentration of an aqueous solution of the natural gas hydrate kinetic inhibitor containing a polycyclic structure of the present invention was pumped in. The air in the reactor was evacuated with a vacuum pump, and the temperature was lowered to 4°C. Methane gas was then introduced, and the pressure in the reactor was adjusted to the experimental pressure of 15 MPa. The gas inlet valve of the reactor was closed, and stirring was started at a speed of 1000 r / min. Finally, the pressure and temperature data in the reactor were monitored and collected. Before hydrate formation, the temperature and pressure in the reactor were stable. When hydrate formation occurred, the pressure dropped sharply and the temperature increased accordingly. This allowed the hydrate inhibition time to be determined.

[0086] Maximum supercooling degree: first, the reactor is cleaned with distilled water, and the cleaning liquid is discharged; then, the natural gas hydrate kinetic inhibitor containing a polybasic ring structure of the present application with a concentration of 0.5% is pumped into the reactor, the air in the reactor is pumped out by a vacuum pump, and then methane gas is introduced, the pressure in the reactor is adjusted to the experimental pressure of 15 MPa, the gas inlet valve of the reactor is closed, the stirring is started, the rotating speed is 1000 r / min, the constant cooling rate is 1 ℃ / h, and the reactor is cooled from 20 ℃ to -10 ℃ to induce the formation of hydrate; finally, the pressure and temperature data in the reactor are monitored and collected, before the formation of hydrate, the temperature and pressure in the reactor decrease at a constant rate, when the hydrate is formed, the pressure will suddenly drop, and the temperature will rise accordingly. The rapid decrease of pressure in the curve indicates the beginning of hydrate formation, and the hydrate formation temperature (the inflection point of the sharp pressure drop). The maximum supercooling degree is the difference between the critical temperature of hydrate corresponding to the pressure at this time and the initial hydrate formation temperature.

[0087] The inhibitory effect of the natural gas hydrate kinetic inhibitor containing a polybasic ring structure prepared in Examples 12 to 14 of the present application was evaluated according to the above-mentioned test method, and the conventional kinetic inhibitors polyvinylpyrrolidone or poly-N-vinylcaprolactam were used as controls. The test results are shown in Table 1. As can be seen from Table 1, compared with the conventional kinetic inhibitors polyvinylpyrrolidone or poly-N-vinylcaprolactam, the natural gas hydrate kinetic inhibitor containing a polybasic ring structure prepared in Examples 12 to 14 of the present application can effectively prolong the hydrate formation time, and can also increase the maximum supercooling degree, and has excellent inhibitory performance.

[0088] In summary, the natural gas hydrate kinetic inhibitor containing a polybasic ring structure of the present application is a kinetic inhibitor. In the process of natural gas injection, production and gathering and transportation, the natural gas hydrate kinetic inhibitor containing a polybasic ring structure of the present application is added, which can participate in the formation of hydrate crystal structure through the unique polybasic ring, effectively inhibit the growth of hydrate crystal, and prevent the formation of large-particle hydrate, and has the advantages of good inhibitory effect, small amount, and low comprehensive cost. At the same time, the supercooling degree application range can be expanded.

[0089] The above technical features constitute an embodiment of the present application, which has strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the needs of different situations.

[0090] Table 1

[0091] name Hydrate inhibition time, min distilled water 20 Distilled water + 0.5% Example 12 2880 Distilled water + 0.5% Example 13 2520 Distilled water + 0.5% Example 14 5520 Distilled water + 0.5% polyvinylpyrrolidone 720 Distilled water + 0.5% poly N-vinyl caprolactam 1600

[0092] Table 2

[0093] name Maximum subcooling, ℃ distilled water 2.9 Distilled water + 0.5% Example 12 13.5 Distilled water + 0.5% Example 13 12.8 Distilled water + 0.5% Example 14 14.3 Distilled water + 0.5% polyvinylpyrrolidone 5.6 Distilled water + 0.5% poly N-vinyl caprolactam 9.2

Claims

1. A natural gas hydrate kinetic inhibitor containing a polycyclic structure, characterized in that Its structural formula is: Here, x is 6 to 12, y is 4 to 16, and z is 4 to 8.

2. The natural gas hydrate kinetic inhibitor containing a polycyclic structure according to claim 1, characterized in that The raw materials include, by weight, 20 to 60 parts of acryloylmorpholine, 10 to 40 parts of maleic anhydride, 30 to 60 parts of dimethylaminopropyl acrylamide, 60 to 120 parts of isohexanediol, 0.1 to 2 parts of initiator, 0.1 to 0.5 parts of chain transfer agent and 0.1 to 0.5 parts of chain terminator.

3. The natural gas hydrate kinetic inhibitor containing a polycyclic structure according to claim 2, characterized in that The initiator is a mixture of hydrogen peroxide and vitamin C or azobisisobutyronitrile, wherein the mass ratio of hydrogen peroxide to vitamin C in the mixture of hydrogen peroxide and vitamin C is 1 to 2:

1.

4. The natural gas hydrate kinetic inhibitor containing a polycyclic structure according to claim 2 or 3, characterized in that The chain transfer agent is one of dodecyl mercaptan and thioglycolic acid.

5. The natural gas hydrate kinetic inhibitor containing a polycyclic structure according to claim 2 or 3, characterized in that The chain terminator is one of hydroquinone, p-tert-butylcatechol and acetone thiosemicarbazone.

6. The natural gas hydrate kinetic inhibitor containing a polycyclic structure according to claim 4, characterized in that The chain terminator is one of hydroquinone, p-tert-butylcatechol and acetone thiosemicarbazone.

7. The natural gas hydrate kinetic inhibitor containing a polycyclic structure according to claim 2, 3 or 6, characterized in that Obtained as follows: S1, adding required amounts of maleic anhydride, acryloylmorpholine, and dimethylaminopropylacrylamide to a required amount of isohexylene glycol in sequence under stirring to obtain a mixed solution; S2, adding a required amount of initiator to the mixed solution to react to obtain an intermediate product 1; S3, adding a required amount of chain transfer agent to the intermediate product 1 and continuing the reaction to obtain the intermediate product 2; S4, adding a required amount of chain terminator to the intermediate product 2 and reacting again to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

8. The natural gas hydrate kinetic inhibitor containing a polycyclic structure according to claim 7, characterized in that In step S2, the reaction temperature is 40° C. to 80° C., and the reaction time is 0.5 h to 1.0 h.

9. The natural gas hydrate kinetic inhibitor containing a polycyclic structure according to claim 7, characterized in that In step S3, the reaction time is 2 h to 8 h, and in step S4, the reaction time is 0.5 h to 2.0 h.

10. The natural gas hydrate kinetic inhibitor containing a polycyclic structure according to claim 8, characterized in that In step S3, the reaction time is 2 h to 8 h, and in step S4, the reaction time is 0.5 h to 2.0 h.

11. A method for preparing a natural gas hydrate kinetic inhibitor containing a polycyclic structure according to any one of claims 2 to 6 and 8 to 10, characterized in that Proceed as follows: S1, adding required amounts of maleic anhydride, acryloylmorpholine, and dimethylaminopropylacrylamide to a required amount of isohexylene glycol in sequence under stirring to obtain a mixed solution; S2, adding a required amount of initiator to the mixed solution to react to obtain an intermediate product 1; S3, adding a required amount of chain transfer agent to the intermediate product 1 and continuing the reaction to obtain the intermediate product 2; S4, adding a required amount of chain terminator to the intermediate product 2 and reacting again to obtain a natural gas hydrate kinetic inhibitor containing a polycyclic structure.

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