Kinetic hydrate inhibitor and compound hydrate inhibitor

Abstract

The invention provides a kinetic hydrate inhibitor and a compound hydrate inhibitor. The chemical structural formula of the kinetic hydrate inhibitor is as follows: # imgabs0 # x: y is equal to 0.5-2, x is equal to 8-20, and y is equal to 10-16; n is equal to 6-9. The compound hydrate inhibitor comprises the kinetic hydrate inhibitor and ethylene glycol in a mass ratio of 1: 5-1: 10, or comprises the kinetic hydrate inhibitor and methanol in a mass ratio of 1: 15-1: 30. The kinetic hydrate inhibitor and the compound hydrate inhibitor provided by the invention have the characteristics of high cloud point and strong inhibition performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas pipeline flow assurance, and in particular relates to a high-performance, high-cloud point kinetic hydrate inhibitor and a compound hydrate inhibitor formed by compounding the kinetic hydrate inhibitor. Background Art

[0002] Hydrate formation in natural gas pipeline systems may block pipelines, which in severe cases may cause significant economic losses or even casualties. Hydrate blockage has become a major threat to flow safety.

[0003] The oil and gas industry mainly uses the method of injecting inhibitors to inhibit the formation of natural gas hydrates and avoid hydrates blocking pipelines and causing safety accidents. Among them, hydrate inhibitors are divided into kinetic inhibitors, thermodynamic inhibitors and anti-agglomeration agents. Thermodynamic inhibitors such as methanol and ethanol can change the thermodynamic conditions of hydrate formation and are an effective method to inhibit hydrate formation. They are the most widely used, but they have disadvantages such as large dosage and high negative environmental impact. Anti-agglomeration agents are not suitable under conditions of high water content. Kinetic inhibitors can reduce the growth rate and generation rate of hydrates. By adsorbing on the surface of hydrate nuclei, they disrupt the nucleation and growth process of hydrates, thereby inhibiting the formation of hydrates. They have the advantage of low dosage. At present, the widely used kinetic inhibitors mainly include polymer kinetic inhibitors such as PVP and PVCap. These polymer kinetic inhibitors have low turbidity points (usually 30-40°C). Inhibitor precipitation often occurs in areas with drastic temperature changes such as throttling elements and heating devices in natural gas pipeline systems, thereby affecting their inhibition performance.

[0004] Therefore, it is necessary to study high cloud point hydrate inhibitors to effectively reduce the risk of hydrate formation and blockage in the natural gas pipeline system, which is of great significance to the flow assurance of natural gas pipelines. Summary of the invention

[0005] An object of the present invention is to provide a hydrate inhibitor having a high cloud point and strong inhibitory performance.

[0006] In order to achieve the above object, the present invention provides the following technical solutions.

[0007] In a first aspect, the present invention provides a kinetic hydrate inhibitor, wherein the chemical structural formula of the kinetic hydrate inhibitor is as follows:

[0008]

[0009] Among them, x:y=0.5-2.0, x=8-20, y=10-16; n=6-9.

[0010] According to a preferred embodiment of the first aspect, the weight average molecular weight Mw of the kinetic hydrate inhibitor is 6000-10000 (eg 8933).

[0011] According to a preferred embodiment of the first aspect, the number average molecular weight Mn of the kinetic hydrate inhibitor is 1000-3000 (eg 1727).

[0012] The kinetic hydrate inhibitor provided by the present invention is based on the structure of the existing kinetic inhibitor polyvinyl caprolactam, by modifying the polyvinyl caprolactam, adding polyethylene glycol methyl ether methacrylate as a reaction monomer and adding thioglycolic acid as a chain transfer agent to carry out polymerization reaction, so as to increase its cloud point and improve its inhibition performance.

[0013] In a second aspect, the present invention provides a method for preparing the kinetic hydrate inhibitor provided in the first aspect, wherein the method comprises:

[0014] N-vinyl caprolactam, polyethylene glycol methyl ether methacrylate, 2,2-azobisisobutyronitrile thioglycolate, 2,2-azobisisobutyronitrile and an organic solvent are mixed to obtain a uniformly mixed reaction system; wherein the amount ratio of N-vinyl caprolactam, polyethylene glycol methyl ether methacrylate, 2,2-azobisisobutyronitrile thioglycolate, 2,2-azobisisobutyronitrile and the organic solvent is 60-120mmol:10-20mmol:0.1-0.5mmol:1-3mmol:80ml;

[0015] The uniformly mixed reaction system is subjected to deoxygenation treatment, and then reacted at a temperature of 70-90° C. for 4-6 hours to obtain a solution containing the kinetic hydrate inhibitor.

[0016] The preparation method of the kinetic hydrate inhibitor provided by the present invention uses N-vinyl caprolactam and polyethylene glycol methyl ether methacrylate as reaction monomers, uses thioglycolic acid 2,2-azobisisobutyronitrile as a chain transfer agent, and uses 2,2-azobisisobutyronitrile as an initiator to carry out a polymerization reaction.

[0017] According to a preferred embodiment of the second aspect, the method for preparing a kinetic hydrate inhibitor further comprises:

[0018] performing rotary evaporation on the solution containing the kinetic hydrate inhibitor to remove the organic solvent;

[0019] Then, the product obtained by rotary evaporation is filtered and washed with n-hexane and tetrahydrofuran to remove impurities such as unreacted substances, thereby obtaining the kinetic hydrate inhibitor;

[0020] Wherein, filtering and washing the product obtained by rotary evaporation with n-hexane and tetrahydrofuran comprises:

[0021] 1) First, tetrahydrofuran is added dropwise to the product until the product is dissolved;

[0022] 2) adding n-hexane to the solution obtained by dissolving in step 1) to form a precipitate;

[0023] 3) filtering out the precipitate obtained in step 2);

[0024] 4) Repeating steps 1) to 3) at least twice with the precipitate as the product, and finally obtaining the precipitate which is the purified kinetic hydrate inhibitor.

[0025] According to a preferred embodiment of the second aspect, N-vinyl caprolactam, polyethylene glycol methyl ether methacrylate, 2,2-azobisisobutyronitrile thioglycolate, 2,2-azobisisobutyronitrile and an organic solvent are mixed to obtain a uniformly mixed reaction system comprising:

[0026] Dissolving N-vinyl caprolactam in an organic solvent to prepare an N-vinyl caprolactam solution;

[0027] Add 2,2-azobisisobutyronitrile to the N-vinylcaprolactam solution and mix evenly; then add polyethylene glycol methyl ether methacrylate and thioglycolic acid and mix evenly to obtain a uniformly mixed reaction system.

[0028] According to a preferred embodiment of the second aspect, the number average molecular weight of the polyethylene glycol methyl ether methacrylate is 475.

[0029] According to a preferred embodiment of the second aspect, the organic solvent is toluene and / or carbon tetrachloride.

[0030] In a third aspect, the present invention provides a composite hydrate inhibitor, wherein the composite hydrate inhibitor comprises the kinetic hydrate inhibitor provided in the first aspect of the present invention and ethylene glycol in a mass ratio of 1:5-1:10, or comprises the kinetic hydrate inhibitor provided in the first aspect of the present invention and methanol in a mass ratio of 1:15-1:30.

[0031] The composite hydrate inhibitor provided by the present invention combines the advantages of thermodynamic hydrate inhibitors and kinetic hydrate inhibitors, and further improves its inhibition performance and cloud point by adding ethylene glycol (MEG) or methanol thermodynamic inhibitor on the basis of the special kinetic hydrate inhibitor provided by the present invention.

[0032] The kinetic hydrate inhibitor and compound hydrate inhibitor provided by the present invention have excellent high cloud point and high inhibition performance characteristics, which helps to reduce the negative impact of throttling elements, heating devices and other areas with drastic temperature changes on the effect of kinetic inhibitors, expand the application range of kinetic hydrate inhibitors, and have important significance for the flow assurance of natural gas pipelines. In addition, the kinetic hydrate inhibitor and compound hydrate inhibitor provided by the present invention have low dosage, and only 1wt% of the addition amount is required to effectively inhibit the formation of natural gas hydrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the gel permeation chromatography elution curve of the kinetic hydrate inhibitor provided in Example 1.

[0034] Figure 2 This is the gel permeation chromatography molecular distribution curve of the kinetic hydrate inhibitor provided in Example 1.

[0035] Figure 3 This is the hydrogen-1 nuclear magnetic resonance spectrum of the kinetic hydrate inhibitor provided in Example 1.

[0036] Figure 4 This is a pressure / temperature-time curve diagram in the test kettle during the induction period test in the inhibition performance test in Example 1.

[0037] Figure 5 Schematic diagram of chemical shifts corresponding to the groups of the kinetic hydrate inhibitor provided in Example 1.

[0038] Figure 6 This is a schematic diagram showing that the aqueous solution of the sample to be tested shows signs of fog during the turbidity point test in Example 1. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0040] Example 1

[0041] This embodiment provides a kinetic hydrate inhibitor, wherein the kinetic hydrate inhibitor is prepared by the following preparation method:

[0042] (1) dissolving 68 mmol of the first monomer N-vinyl caprolactam (PVCap, 99% GC) in 80 ml of toluene to prepare an N-vinyl caprolactam solution;

[0043] (2) adding 1.6 mmol of initiator 2,2-azobisisobutyronitrile (AIBN, 99% recrystallized) to the N-vinyl caprolactam solution prepared in step (1) and mixing evenly; then adding 12 mmol of the second monomer polyethylene glycol methyl ether methacrylate (PEOMA, >98% GC) and 0.2 mmol of chain transfer agent thioglycolic acid (>95% AR) and mixing evenly to obtain a uniformly mixed reaction system;

[0044] (3) deoxygenating the uniformly mixed reaction system, and then reacting at 80° C. for 3.5 hours to obtain a solution containing a kinetic hydrate inhibitor;

[0045] (4) using a rotary evaporator to perform rotary evaporation on the solution containing the kinetic hydrate inhibitor obtained in step (3) to remove the organic solvent; then filtering and washing the product obtained by rotary evaporation with n-hexane and tetrahydrofuran to remove impurities such as unreacted substances, thereby obtaining the kinetic hydrate inhibitor PV-S;

[0046] Wherein, filtering and washing the product obtained by rotary evaporation with n-hexane and tetrahydrofuran comprises:

[0047] 1) First, tetrahydrofuran is added dropwise to the product until the product is dissolved;

[0048] 2) adding n-hexane to the solution obtained by dissolving in step 1) to form a precipitate;

[0049] 3) filtering out the precipitate obtained in step 2);

[0050] 4) Repeat steps 1) to 3) twice with the precipitate as the product, and the final precipitate obtained is the kinetic hydrate inhibitor PV-S.

[0051] Kinetic Hydrate Inhibitor Performance Test

[0052] 1. The prepared kinetic hydrate inhibitor PV-S was characterized by gel permeation chromatography (GPC) and nuclear magnetic resonance hydrogen spectroscopy (NMR). GPC mainly obtained the molecular weight range of the product, and NMR obtained the molecular configuration of the product.

[0053] Gel permeation chromatography detection: Agilent 1260 device was used to perform gel permeation chromatography on the prepared kinetic hydrate inhibitor PV-S. The elution curve and molecular distribution curve were obtained by chromatograph detection. Figure 1 , Figure 2 As shown, the average molecular weight of the kinetic hydrate inhibitor was obtained at the same time, wherein the weight average molecular weight Mw was 8933 and the number average molecular weight Mn was 1727;

[0054] Nuclear magnetic resonance hydrogen spectrum detection: The prepared kinetic hydrate inhibitor PV-S was tested by nuclear magnetic resonance hydrogen spectrum using Bruker AVANCE III HD 400M device. The nuclear magnetic resonance spectrum of hydrogen-1 of the kinetic hydrate inhibitor was obtained by the instrument. Figure 3 shown.

[0055] The kinetic hydrate inhibitor PV-S is obtained by copolymerizing two monomers, N-vinyl caprolactam and polyethylene glycol methyl ether methacrylate, and the structural formula of the reaction product is:

[0056]

[0057] The structure of the kinetic hydrate inhibitor PV-S was verified by hydrogen nuclear magnetic resonance spectrum detection. Combining the structural formula and the common chemical shifts of hydrogen nuclear magnetic resonance (H-NMR), the chemical shifts corresponding to different groups in the molecular formula can be obtained, such as Figure 5 As shown, there are only four groups, b, c, i, and h, whose chemical shifts are above 3 ppm. Figure 3 As shown, the corresponding absorption peaks can be found in the spectrum. Among them, c corresponds to a triplet, which is consistent with the chemical environment of CH-N, the signal of b is too strong and it is difficult to distinguish the splitting number, j is -O-CH3 connected only to oxygen, i corresponds to the chemical shift of the ester group, and the peaks above 5ppm are solvent peaks and other impurities. The number of protons is quantitatively calculated by integrating the peak area. Since the hydrogen atom has only one proton, the ratio of group hydrogen atoms can also be obtained. Thus, the ratio of hydrogen atoms of group a to group c is 0.48:1. Considering that the ratio of hydrogen atoms attached to the two groups is 1:3, the x:y is obtained as 1.44. It can be seen that the structural formula of the kinetic hydrate inhibitor PV-S is shown above, where x / y=1.44, its average molecular weight Mw is 8933, and Mn is 1727.

[0058] 2. The turbidity point and inhibition performance of the prepared kinetic hydrate inhibitor PV-S and the N-vinyl caprolactam PVCap used to prepare the kinetic hydrate inhibitor PV-S were tested.

[0059] Turbidity point detection: A. First, dissolve the sample to be tested in deionized water to form a sample solution with a mass concentration of 1wt%; B. Place the sample solution in a transparent reagent bottle, and place the transparent reagent bottle in a thermally stable water bath; C. Slowly increase the water bath temperature from room temperature (20°C) at a heating rate of 0.5°C per minute, observe the sample solution in the transparent reagent bottle, and measure the water bath temperature using a digital thermometer with an accuracy of ±0.1K; D. The sample solution begins to show a temperature of Figure 6The temperature at which fogging is observed is recorded as the cloud point temperature; E. Repeat steps A to D three times for each sample to be tested, and take the average of the three cloud point temperatures as the cloud point temperature of the sample to be tested.

[0060] The results are shown in Table 1. The turbidity point of the kinetic hydrate inhibitor PV-S is increased by 9°C compared to the traditional kinetic inhibitor PVCap, and the turbidity point of the original PVCap is increased by 23.7%, which is a significant effect.

[0061] Table 1

[0062] Type of samples to be tested Cloud point(℃) PVCap 38℃ PV-S 47℃

[0063] Inhibition performance test: A five-reactor linkage swing reactor device is used to carry out hydrate formation experiments, test the hydrate formation induction period of the test sample system, and then characterize the inhibition performance of the test sample; specifically including:

[0064] A. Solution preparation: dissolve the sample to be tested in deionized water to form an aqueous solution of the sample to be tested with a mass concentration of 1 wt %; B. Liquid addition and gas injection: introduce the prepared aqueous solution of the sample to be tested into the test kettle. Open the air inlet valve and fill the test kettle with natural gas. After the natural gas is filled, in order to ensure that there is no leakage in the test kettle, the gas pressure in the kettle is maintained at 9MPa and there is no obvious change for 30 minutes; C. Induction period test: the initial temperature is set to 20℃, and then the power swing device is started to fully mix the liquid in the test kettle; adjust the temperature to the target temperature of hydrate formation of 1℃, wait for the temperature in the test kettle to reach the target temperature of hydrate formation, and collect and record the pressure and temperature in the test kettle; wait for the temperature and pressure in the test kettle to stabilize (the pressure and temperature must remain unchanged within 10 minutes), and then the induction period test is over; D. Post-experimental work: After the induction period test is over, first adjust the temperature to 20℃, and wait for the test kettle to reach a stable state; then, disassemble the experimental equipment and clean it thoroughly; after cleaning, turn off the power of the equipment and let the equipment cool naturally; E. Repeat the experiment three times for each sample to be tested and take the average value of the induction period.

[0065] Figure 4 The dynamic changes of temperature and pressure in the test reactor over time are shown. According to the evolution of parameters, the hydrate formation process can be divided into four main stages:

[0066] Natural gas dissolution stage: In this stage, the test kettle is kept under high pressure; the experimental gas is fully mixed with the liquid under the action of dynamic stirring and gradually dissolved in the liquid until a stable state is reached, and hydrates have not yet formed;

[0067] Hydrate nucleation induction stage: As the temperature of the test kettle continues to drop, when the temperature and pressure reach the conditions for hydrate formation, water molecules and gas molecules begin to aggregate to form clusters, and gradually grow to a critical size. This stage ends when the pressure in the system changes significantly.

[0068] Hydrate growth stage: Hydrates are initially formed at the gas-liquid interface. During this stage, as the gas continues to be consumed, the volume of the hydrates continues to increase, which causes the pressure in the test reactor to drop significantly.

[0069] Hydrate decomposition stage: Since the induction period test has ended, the water bath temperature in this stage is set to 20°C. As the system temperature continues to rise, hydrates begin to decompose continuously, and the system pressure continues to increase with the release of natural gas in the hydrates. Finally, as the system pressure tends to stabilize, the hydrate decomposition stage is completed.

[0070] The duration of the hydrate nucleation induction phase, namely the induction period, is used as an evaluation index of the inhibitor performance.

[0071] The induction period data of each group of samples are shown in Table 2. The characterization results show that the inhibition performance of the kinetic hydrate inhibitor PV-S is significantly improved compared with the traditional kinetic inhibitor PVCap. Compared with the hydrate induction period of 10.04h in the 1wt% PVCap system, it is increased by 25.7% to 12.62h.

[0072] Table 2

[0073] Sample Type Average induction period (h) Extension times No inhibitor blank group 0.52 1.00 PVCap 10.04 19.31 PV-S 12.62 24.27

[0074] Example 2

[0075] This embodiment provides a composite hydrate inhibitor PV-S+MEG.

[0076] The composite hydrate inhibitor PV-S+MEG comprises the kinetic hydrate inhibitor provided in Example 1 of the present invention and ethylene glycol MEG in a mass ratio of 3:20.

[0077] Performance test of compound hydrate inhibitor

[0078] 1. The composite hydrate inhibitor PV-S+MEG and the composite hydrate inhibitor PVCap+MEG provided in this embodiment are subjected to turbidity point detection; wherein the composite hydrate inhibitor PVCap+MEG comprises N-vinyl caprolactam PVCap and ethylene glycol MEG used in Example 1 in a mass ratio of 3:20.

[0079] Turbidity point detection: A. First, dissolve the sample to be tested in deionized water to form a water solution of the sample to be tested; the mass concentration of MEG in the water solution of the sample to be tested is 10%, and the mass concentration of PVCapB or PV-S is 1.5%; place the water solution of the sample to be tested in a transparent reagent bottle, and place the transparent reagent bottle in a heat-stable water bath; C. Slowly increase the water bath temperature from room temperature (20°C) at a heating rate of 0.5°C per minute, observe the water solution of the sample to be tested in the transparent reagent bottle, and measure the water bath temperature using a digital thermometer with an accuracy of ±0.1K; D. The water solution of the sample to be tested begins to show Figure 6 The temperature at which fogging is observed is recorded as the cloud point temperature; E. Repeat steps A to D three times for each sample to be tested, and take the average of the three cloud point temperatures as the cloud point temperature of the sample to be tested.

[0080] The results are shown in Table 3.

[0081] Table 3

[0082] Type of samples to be tested Cloud point(℃) PV-S+MEG 55℃ PVCap+MEG 42℃

[0083] As shown in Tables 1 and 3, the addition of ethylene glycol, a thermodynamic hydrate inhibitor, can improve the disadvantage of a single inhibitor with a low turbidity point. The combination of PV-S+MEG has a significant effect, which can increase the turbidity point to 55°C, which is 44.7% higher than the traditional commercial inhibitor PVCap. This helps to reduce the negative impact of throttling elements, heating devices and other areas with drastic temperature changes on the effect of kinetic inhibitors.

[0084] 2. The inhibition performance of the composite hydrate inhibitor PV-S+MEG, the composite hydrate inhibitor PVCap+MEG and the ethylene glycol MEG provided in this embodiment was tested; wherein the composite hydrate inhibitor PVCap+MEG comprises N-vinyl caprolactam PVCap and ethylene glycol MEG used in Example 1 in a mass ratio of 3:20.

[0085] Inhibition performance test: A five-reactor linkage swing reactor device is used to carry out hydrate formation experiments, test the hydrate formation induction period of the test sample system, and then characterize the inhibition performance of the test sample; specifically including:

[0086] A. Solution preparation: dissolve the sample to be tested in deionized water to form a water solution of the sample to be tested; the mass concentration of MEG in the water solution of the sample to be tested is 10%, and when it contains PVCapB or PV-S, the mass concentration of PVCapB and PV-S is 1.5%; B. Liquid addition and gas injection: introduce the prepared water solution of the sample to be tested into the test kettle. Open the air inlet valve and fill the test kettle with natural gas. After the natural gas is filled, in order to ensure that there is no leakage in the test kettle, the gas pressure in the kettle is maintained at 9MPa and there is no obvious change for 30 minutes; C. Induction period test: the initial temperature is set to 20℃, and then the power swing device is started to fully mix the liquid in the test kettle; adjust the temperature to the target temperature of hydrate formation of 1℃, wait for the temperature in the test kettle to reach the target temperature of hydrate formation, and collect and record the pressure and temperature in the test kettle; wait for the temperature and pressure in the test kettle to stabilize (the pressure and temperature must remain unchanged within 10 minutes), and then the induction period test is over; D. Post-experimental work: After the induction period test is over, first adjust the temperature to 20℃, and wait for the test kettle to reach a stable state; then, disassemble the experimental equipment and clean it thoroughly; after cleaning, turn off the power of the equipment and let the equipment cool naturally; E. Repeat the experiment three times for each sample to be tested and take the average value of the induction period.

[0087] The results are shown in Table 4.

[0088] Table 4

[0089] Sample Type Average induction period (h) Extension times No inhibitor blank group 0.52 1.00 MEG 0.55 1.05 PV-S+MEG ＞68 ＞130.77 PVCap+MEG 23.64 45.46

[0090] As shown in Table 2 and Table 4, the composite hydrate inhibitor provided by the present invention combines the advantages of thermodynamic and kinetic hydrate inhibitors, and can significantly improve the inhibition performance while increasing the cloud point compared to a single hydrate kinetic inhibitor. Characterization results show that the modified product compounded with ethylene glycol (PV-S+MEG) has the best effect, and can extend the induction period to more than 68h, which is more than 130 times higher than the blank group without adding inhibitors, and has better inhibition performance than the traditional commercial inhibitor PVCap, and its induction period is increased by more than 58h.

[0091] In summary, the hydrate inhibitor provided by the present invention has excellent high cloud point and high inhibition performance characteristics, which helps to reduce the negative impact of drastic temperature change areas such as throttling elements and heating devices on the effect of kinetic inhibitors, expand the application scope of kinetic hydrate inhibitors, and is of great significance to the flow assurance of natural gas pipelines.

[0092] The embodiments described above are for better explaining the present invention. For technical researchers in the field, it is not difficult to make various modifications to these embodiments without departing from the principles and spirit of the present invention. Therefore, the present invention is not limited to the embodiments herein. The improvements and changes made by those skilled in the art to the present invention according to the principles and spirit of the present invention should be within the protection scope of the present invention.

Claims

1. A kinetic hydrate inhibitor, wherein: The chemical structure of the kinetic hydrate inhibitor is shown below: Among them, x:y=0.5-2.0, x=8-20, y=10-16; n=6-9.

2. The kinetic hydrate inhibitor according to claim 1, wherein: The weight average molecular weight Mw of the kinetic hydrate inhibitor is 6000-10000.

3. The kinetic hydrate inhibitor according to claim 1, wherein: The number average molecular weight Mn of the kinetic hydrate inhibitor is 1000-3000.

4. The method for preparing a kinetic hydrate inhibitor according to any one of claims 1 to 3, wherein: The method includes: N-vinyl caprolactam, polyethylene glycol methyl ether methacrylate, 2,2-azobisisobutyronitrile thioglycolate, 2,2-azobisisobutyronitrile and an organic solvent are mixed to obtain a uniformly mixed reaction system; wherein the amount ratio of N-vinyl caprolactam, polyethylene glycol methyl ether methacrylate, 2,2-azobisisobutyronitrile thioglycolate, 2,2-azobisisobutyronitrile and the organic solvent is 60-120mmol:10-20mmol:0.1-0.5mmol:1-3mmol:80ml; The uniformly mixed reaction system is subjected to deoxygenation treatment, and then reacted at a temperature of 70-90°C for 4-6 hours to obtain a solution containing the kinetic hydrate inhibitor.

5. The preparation method according to claim 4, wherein The preparation method of the kinetic hydrate inhibitor also includes: performing rotary evaporation on the solution containing the kinetic hydrate inhibitor to remove the organic solvent; Then, the product obtained by rotary evaporation is filtered and washed with n-hexane and tetrahydrofuran to remove impurities such as unreacted substances, thereby obtaining the kinetic hydrate inhibitor.

6. The preparation method according to claim 5, wherein: The product obtained by rotary evaporation is filtered and washed with n-hexane and tetrahydrofuran, including: 1) First, tetrahydrofuran is added dropwise to the product until the product is dissolved; 2) adding n-hexane to the solution obtained by dissolving in step 1) to form a precipitate; 3) filtering out the precipitate obtained in step 2); 4) Repeating steps 1) to 3) at least twice with the precipitate as the product, and finally obtaining the precipitate which is the purified kinetic hydrate inhibitor.

7. The preparation method according to claim 4, wherein N-vinyl caprolactam, polyethylene glycol methyl ether methacrylate, 2,2-azobisisobutyronitrile thioglycolate, 2,2-azobisisobutyronitrile and an organic solvent are mixed to obtain a uniformly mixed reaction system comprising: Dissolving N-vinyl caprolactam in an organic solvent to prepare an N-vinyl caprolactam solution; Add 2,2-azobisisobutyronitrile to the N-vinylcaprolactam solution and mix evenly; then add polyethylene glycol methyl ether methacrylate and thioglycolic acid and mix evenly to obtain a uniformly mixed reaction system.

8. The preparation method according to claim 4, wherein The number average molecular weight of polyethylene glycol methyl ether methacrylate is 475.

9. The preparation method according to claim 4, wherein: The organic solvent is toluene and / or carbon tetrachloride.

10. A composite hydrate inhibitor, wherein: The composite hydrate inhibitor comprises the kinetic hydrate inhibitor according to any one of claims 1 to 3 and ethylene glycol in a mass ratio of 1:5 to 1:10, or comprises the kinetic hydrate inhibitor according to any one of claims 1 to 3 and methanol in a mass ratio of 1:15 to 1:30.

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