Hydrate polymerization inhibitor as well as preparation method and application thereof

Abstract

The invention discloses a hydrate polymerization inhibitor as well as a preparation method and application thereof. The hydrate polymerization inhibitor comprises a pretreated asphaltene mixture, an active treatment agent and a synergist, wherein the pretreated asphaltene mixture comprises asphaltene, an anhydride treatment agent, a reaction initiator and a dissolution dispersant. The hydrate polymerization inhibitor can effectively hinder aggregation of hydrate particles and prevent hydrate from blocking pipes, has small influence on the properties of crude oil, also has the advantages of low cost and high use efficiency, and can provide a feasible method for risk management of hydrates in seabed multiphase pipelines in the petroleum and natural gas transportation process.

Description

Technical Field

[0001] The invention relates to the technical field of oil and natural gas production, and in particular to an asphaltene-based composite hydrate inhibitor and a preparation method and application thereof. Background Art

[0002] Hydrate research began in the early 19th century and is currently attracting attention in many fields such as pipeline flow safety, energy conservation and energy storage, hydrate-based low-carbon technology, and gas storage. In the field of pipeline flow safety, hydrates can appear in multiphase pipelines under appropriate conditions and threaten pipeline operation safety. Due to the presence of natural surfactants in crude oil, the oil and water phases in submarine pipelines mostly appear in the form of oil-in-water emulsions. When the temperature, pressure, and system composition in the pipe reach the conditions for hydrate formation, water droplets will transform into hydrate particles at the end of the induction period.

[0003] The generated hydrate particles aggregate under the action of capillary liquid bridge force and can form particles or block objects, and the hydrate particles can also be deposited on the inner wall of the pipeline, which seriously threatens the operation safety of the pipeline and may block the pipeline in serious cases. In order to prevent the generated hydrate from blocking the pipeline, the hydrate treatment method has received more and more attention in the production and transportation of oil and natural gas.

[0004] The traditional hydrate management and control method mainly adds thermodynamic inhibitors based on methanol or ethylene glycol. This method can avoid the appearance of hydrates by changing the thermodynamic conditions of hydrate formation. With the consideration of economic agents and environmental protection, low-dose kinetic inhibitors have gradually begun to be used. Kinetic inhibitors mainly avoid hydrate blocking by extending the induction period of hydrates. However, the nucleation of hydrates is a random process, and there is a certain uncertainty in completely avoiding the formation of hydrates by hydrate inhibitors. With the continuous deepening of research, the management measures of hydrates have gradually changed from completely avoiding the formation of hydrates to risk control. The risk control strategy of hydrates is to make hydrates flow in the form of a relatively stable slurry, which broadens the methods of hydrate management and ensures the safe operation of pipelines. The key to the hydrate risk control strategy is the application of low-dose hydrate inhibitors. Hydrate inhibitors can be adsorbed on the surface of water droplets to stabilize the emulsion before hydrates are formed, thereby reducing the particle size of the generated hydrate particles. At the same time, inhibitors can inhibit the aggregation of hydrates, so that they are dispersed in the liquid phase in the form of particles and transported stably without a large amount of aggregation to block the pipeline.

[0005] CN105090747B discloses a composite hydrate inhibitor containing rhamnolipid. The method comprises compounding a rhamnolipid biosurfactant and a polyol-type nonionic surfactant to prepare a hydrate inhibitor, and inhibiting the aggregation process of hydrate particles by changing the hydrophilicity of the hydrate surface. However, the method requires the addition of a large amount of surfactant, which increases the pipeline operation cost and the difficulty of oil, gas and water three-phase separation.

[0006] CN107314245B discloses a compound hydrate inhibitor composition containing lecithin and its use. The method comprises mixing a polyol nonionic surfactant, a lecithin zwitterionic surfactant and a compound synergist to prepare the hydrate inhibitor. However, the addition of a large amount of reagents will increase the liquid phase viscosity and running friction, and increase the energy consumption during the pipeline operation process.

[0007] Currently, the hydrate inhibitors used are mainly amphiphilic surfactants, and typical types of inhibitors include quaternary ammonium salt surfactants and sorbitan. Inhibitors can be adsorbed on the surface of water droplets and hydrate particles, reducing the capillary liquid bridge effect between hydrate particles and dispersing them. Quaternary ammonium salt hydrate inhibitors have good dispersibility for hydrate particles, but they are toxic and difficult to degrade, which limits their large-scale promotion to a certain extent. Therefore, the development of a new type of hydrate inhibitor is of great significance in the field of hydrate management. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides a hydrate inhibitor and a preparation method and application thereof. The hydrate inhibitor of the present invention can effectively hinder the aggregation of hydrate particles, prevent hydrates from blocking pipes, has little effect on the properties of crude oil, and has the advantages of low cost and high efficiency. It can provide a feasible method for the risk management of hydrates in submarine multiphase pipelines during the transportation of oil and natural gas.

[0009] The first aspect of the present invention provides a hydrate inhibitor, which comprises: a pretreated asphaltene mixture, an active treatment agent and a synergist, wherein the pretreated asphaltene mixture comprises asphaltene, an anhydride treatment agent, a reaction initiator and a dissolving dispersant.

[0010] Furthermore, the mass ratio of the pretreated asphaltene mixture, the active treatment agent and the synergist is 40:(0.01-0.1):(0.1-1).

[0011] Furthermore, in the pretreated asphaltene mixture, the mass ratio of asphaltene, anhydride treating agent, reaction initiator and dissolving dispersant is 1: (0.1-0.5): (0.01-0.05): (5-50).

[0012] Furthermore, asphaltenes can be extracted from vacuum residue, crude oil or asphalt, and the extraction steps can refer to NB / SH / T0509-2010 "Method for Determination of Four Components of Petroleum Asphalt".

[0013] Furthermore, the properties of the asphaltene include: a molecular weight of 500 to 8000, preferably 1000 to 5000; a carbon element mass content of 80wt% to 88wt%; a nitrogen element mass content of 0.5wt% to 2.5wt%; a hydrogen element mass content of 4wt% to 12wt%; a sulfur element mass content of 1.0wt% to 8.0wt%; an oxygen element mass content of 0.5wt% to 5.0wt%; and a hydrogen-to-carbon molar ratio of 1.0 to 1.5, preferably 1.0 to 1.2.

[0014] Furthermore, the acid anhydride treating agent is one or more of maleic anhydride, polyisobutylene succinic anhydride, dodecenyl succinic anhydride, tung oil anhydride, polyazelaic anhydride, polyglutaric anhydride, polyoxalic anhydride or hydrolyzed polymaleic anhydride.

[0015] Furthermore, the reaction initiator is one or more of dicumyl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, sodium pyrosulfite, azobisisobutyronitrile or azobisisoheptanenitrile.

[0016] Furthermore, the dissolving and dispersing agent is one or more of hydrocarbon solvents such as toluene, benzene, xylene, carbon disulfide, chloroform, carbon tetrachloride and methylnaphthalene.

[0017] Furthermore, the active treatment agent is one or more of polyvinyl alcohol (molecular weight of 10,000 to 150,000) or polyethyleneimine (molecular weight of 1,000 to 10,000).

[0018] Furthermore, the synergist is one or more of the non-ionic surfactants Span20, Span40, Span60 or Span80.

[0019] The second aspect of the present invention provides a method for preparing the above-mentioned hydrate inhibitor, comprising the following steps:

[0020] (1) dispersing asphaltene in a dissolving dispersant, adding an anhydride treating agent and a reaction initiator, and treating under stirring to obtain a pretreated asphaltene mixture;

[0021] (2) The pretreated asphaltene mixture obtained in step (1) is mixed with an active treatment agent and a synergist, and stirred to obtain a hydrate inhibitor.

[0022] Furthermore, in step (1), ultrasonic oscillation is used to dissolve and disperse the asphaltene in the dissolving and dispersing agent. The oscillation time is 30 min to 60 min, the temperature is 25° C. to 60° C., and the oscillation frequency is 20 to 40 MHz.

[0023] Furthermore, in step (1), the stirring rate is 100 to 800 rpm; the treatment time is 3 to 5 hours, and the treatment temperature is 60° C. to 90° C.

[0024] Furthermore, in step (2), the stirring rate is 200 rpm to 800 rpm, the stirring temperature is 25° C. to 60° C., and the stirring time is 10 min to 30 min.

[0025] The third aspect of the present invention provides a use of the above-mentioned hydrate inhibitor in an oil-water system.

[0026] Furthermore, the water content of the oil-water system is 5wt% to 50wt%, the oil content is 50wt% to 95wt%, the temperature of the oil-water system is -10°C to 50°C, and the pressure is 0.1MPa to 20.0MPa.

[0027] Furthermore, the added mass of the hydrate inhibitor is 0.5% to 3.5% of the mass of the oil phase in the oil-water system.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) The asphaltene-based hydrate inhibitor of the present invention can significantly inhibit the aggregation of water droplets before hydrate formation, and at the same time hinder the aggregation of hydrate particles, so that hydrates exist in the system in the form of particles, effectively avoiding hydrate blockage, which is beneficial to the risk management of hydrates and can ensure the safe operation of oil-water multiphase pipelines.

[0030] (2) The hydrate inhibitor of the present invention has stronger reaction activity and improves its own hydrophilicity and inhibitory effect by pre-treating asphaltene. The inhibitory effect of low-content asphaltene and synergist on hydrates is enhanced by compounding the components, thereby greatly reducing the content of chemical emulsifier in the inhibitor, and reducing the influence of the inhibitor on pipeline operation and subsequent oil-water separation while efficiently preventing hydrate aggregation.

[0031] (3) The hydrate inhibitor of the present invention uses asphaltene extracted mainly from low-cost residual oil, which is low in cost. At the same time, it improves the economic benefits of residual oil and has significant social benefits. At the same time, the preparation method of the inhibitor is simple and the effect is obvious, which is conducive to promotion and application in oil fields.

[0032] (4) The hydrate inhibitor of the present invention requires less mass when used, does not require the injection of a large amount of additional chemical reagents, has less impact on the properties of crude oil, and reduces the difficulty of subsequent crude oil processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a microscopic picture of the water droplet size of the oil-water system in Comparative Example 1;

[0034] Figure 2 This is a microscopic picture of the water droplet size of the oil-water system in Comparative Example 4;

[0035] Figure 3 This is a microscopic picture of the water droplet size in the oil-water system in Example 1. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below through specific embodiments. The described embodiments are only used to explain the present invention but are not used to limit the protection scope of the present invention.

[0037] The present invention uses a Nikon OPTIPHOT2-POL polarizing microscope to measure the particle sizes of water droplets in the embodiments and comparative examples.

[0038] Comparative Example 1

[0039] The purpose of this comparative example is to determine the dispersed particle size of water droplets in the oil phase before hydrate formation. In the water-in-oil system, the water phase is dispersed in the oil phase in the form of droplets. When hydrates are formed, the water droplets gradually transform into hydrate particles. Therefore, the particle size of the water droplets determines the particle size of the generated hydrate particles.

[0040] This comparative example and other specific examples for testing the water droplet size of the water-in-oil system were observed using an optical microscope.

[0041] The specific steps of measuring the water droplet size using the above optical microscope are as follows:

[0042] (1) Pour 600 mL of diesel and 200 mL of deionized water into a 2 L beaker and place the beaker in a temperature-controlled water bath.

[0043] (2) The oil-water system was stirred with a stirring paddle at a rotation speed of 1000 rpm, the stirring temperature was 4° C., and the stirring time was 15 min.

[0044] (3) After stirring, take an appropriate amount of liquid using a sampling tube and place it on a glass slide to prepare an observation sample. Select the 10× objective lens and observe and photograph at 4°C. Take five different positions of each sample for observation and photography.

[0045] The water droplet size test results are as follows: Figure 1As shown, since no hydrate inhibitor was added in this comparative example, the particle size of the water droplets in the oil-water system was very large. At the same time, after stopping the stirring, the water droplets in the beaker would quickly coalesce to form clearly stratified oil-water phases within 10 minutes.

[0046] Comparative Example 2

[0047] This comparative example uses a high-pressure stirring hydrate reactor to evaluate the hydrate particle aggregation effect. Its structure mainly includes a high-pressure reactor body, a temperature control system, a pressure control system, a stirring system, a parameter measurement and data acquisition system. The oil-in-water system performs the hydrate formation process in the autoclave chamber, the temperature is controlled by a circulating water bath, the pressure is controlled by a high-pressure gas cylinder and a regulating valve, and the stirring is achieved by a magnetic stirrer.

[0048] The specific steps of the evaluation experiment using the above-mentioned high-pressure stirred hydrate reactor are as follows:

[0049] (1) Pour 600 mL of diesel and 200 mL of deionized water into a 2 L beaker in sequence and stir at 1000 rpm for 15 min to obtain an oil-water mixture.

[0050] (2) After cleaning the autoclave cavity, pour the oil-water mixture into it and seal it, and then use a vacuum pump to replace the residual air in the autoclave.

[0051] (3) Turn on the stirring paddle and data acquisition system, set the stirring speed to 400 rpm, and stir the liquid in the kettle.

[0052] (4) Open the gas cylinder and the air inlet valve, gradually introduce gas into the autoclave to 4.0 MPa, and then close the gas cylinder and the air inlet valve to maintain the high pressure environment of the system.

[0053] (5) Set the water bath temperature and gradually lower the temperature in the kettle from room temperature to 4°C. Once the specified temperature is reached, maintain the water bath temperature unchanged.

[0054] (6) When the temperature in the system suddenly rises, it indicates that hydrates begin to form, and the water droplets in the oil-water system gradually transform into hydrate particles.

[0055] (7) As the water droplets transform, the temperature in the system gradually decreases under the action of the circulating water bath, and the pressure also gradually decreases due to the consumption of gas. When the pressure and temperature in the system do not change within 30 min, hydrate formation ends.

[0056] (8) After hydrate formation, stirring was stopped. After 1 h, the stirring paddle was reopened to observe whether the hydrate particles aggregated and affected the stirring paddle. Then, the exhaust valve was opened to release the pressure of the system. When the pressure reached normal pressure, the autoclave was opened to take out the hydrate in the autoclave and observe the state of the hydrate.

[0057] When the hydrate inhibitor takes effect, the hydrate can exist in the oil phase in the form of small-size particles. After stopping stirring, the stirring paddle can be restarted smoothly. After opening the autoclave, it can be observed that the hydrate exists in the form of particles and does not form lumps.

[0058] In this comparative example, no hydrate inhibitor was added. Hydrates were generated quickly after the temperature and pressure conditions were met. When the stirring was stopped for 1 hour and the stirring paddle was restarted, the rotation was blocked. After the stirring paddle was turned off and the pressure was released, it was observed that all the hydrate particles in the autoclave were gathered together to form a block-like whole. This shows that when no hydrate inhibitor was added, the hydrate particles had a significant aggregation effect under the action of capillary liquid bridge force, and it was very likely to block the pipeline at the construction site.

[0059] Comparative Example 3

[0060] This comparative example uses a high-pressure swing reaction device to evaluate the effect of the hydrate inhibitor, and its structure includes a swing kettle body, a temperature control system, a pressure control system, a swing system, and a parameter measurement and data acquisition system. The swing kettle cavity is a transparent tube, and a metal ball is placed in the swing kettle cavity to stir the fluid. When the hydrate particles aggregate, the reciprocating swing motion of the metal ball is hindered, and when the hydrate particles aggregate large enough, the ball stops moving.

[0061] The specific steps of the evaluation experiment using the above-mentioned high-pressure stirred hydrate reactor are as follows:

[0062] (1) Pour 600 mL of diesel and 200 mL of deionized water into a 2 L beaker in sequence and stir at 1000 rpm for 15 min to obtain an oil-water mixture.

[0063] (2) After cleaning the swing kettle cavity, pour the oil-water mixture into it and seal it, and then replace the residual air.

[0064] (3) Turn on the swing motor and data acquisition system to make the reactor cavity swing back and forth periodically.

[0065] (4) Open the gas cylinder and the air inlet valve, gradually introduce gas into the autoclave to 3 MPa, and then close the gas cylinder and the air inlet valve to maintain the high pressure environment of the system.

[0066] (5) Set the water bath temperature and gradually lower the temperature in the kettle from room temperature to 3°C. Once the specified temperature is reached, maintain the water bath temperature unchanged.

[0067] (6) When the temperature in the system suddenly rises, it indicates that hydrates are formed, and the water droplets in the oil-water system gradually transform into hydrate particles.

[0068] (7) As the water droplets transform, solid particles begin to appear in the swing kettle and hinder the movement of the metal balls. When the pressure and temperature in the system do not change within 30 minutes, the evaluation experiment ends.

[0069] When the hydrate inhibitor takes effect, the hydrate can exist in the oil phase in the form of small-size particles. The hydrate will not block the pipeline, and the metal ball will not stop moving or the time required to stop moving will be prolonged.

[0070] In this comparative example, no hydrate inhibitor was added. After the hydrate was generated, the movement speed of the small balls decreased rapidly. At the same time, the movement stopped within 5 minutes due to the aggregation and blocking of the pipe by the hydrate particles. This shows that the hydrate particles can grow and aggregate rapidly in the oil-water system without adding an inhibitor.

[0071] Example 1

[0072] (1) Asphaltene (properties shown in Table 1) was dispersed in toluene by ultrasonic oscillation, the oscillation time was 40 min, the temperature was 40°C, and the oscillation frequency was 40 MHz, and then maleic anhydride and diisopropylbenzene peroxide were added, wherein the mass ratio of asphaltene, maleic anhydride, diisopropylbenzene peroxide and toluene was 1:0.2:0.04:20, and the mixture was treated under stirring at a stirring rate of 300 rpm, a treatment time of 4 h, and a treatment temperature of 80°C to obtain a pretreated asphaltene mixture;

[0073] (2) The pretreated asphaltene mixture obtained in step (1) was mixed with polyethyleneimine (molecular weight 8000) and Span20 in a mass ratio of 40:0.05:0.5 at a stirring rate of 500 rpm, a stirring temperature of 40° C., and a stirring time of 20 min to obtain a hydrate inhibitor.

[0074] According to the experimental conditions of Comparative Example 1, the composite hydrate inhibitor was added before stirring, and the added mass was 1.61% of the mass of the oil phase. The same experimental method was used to observe the water droplet size of the oil-water system.

[0075] Observation results such as Figure 3 As shown, it can be seen that the addition of the hydrate inhibitor significantly reduced the particle size of water droplets in the oil-water system, and no water droplet aggregation was found within 60 minutes after the oil-water system stopped stirring, and no obvious oil-water stratification was found after standing for 12 hours, indicating that the composite inhibitor effectively prevented the aggregation of water droplets and allowed the hydrate particles to flow safely in the pipeline.

[0076] Example 2

[0077] The preparation of the hydrate inhibitor in this example is the same as that in Example 1.

[0078] According to the experimental conditions of Comparative Example 2, the composite hydrate inhibitor provided in this example was added when preparing the emulsion, and the added mass was 1.61% of the mass of the oil phase. The evaluation experiment was carried out using the same experimental method using a high-pressure stirred hydrate reactor.

[0079] Since an asphaltene-based hydrate inhibitor was added to the system, the stirring paddle could be directly restarted smoothly after stopping stirring for 1 hour. After turning off the stirring paddle and releasing the pressure, it was observed that the hydrates in the autoclave existed in the form of dispersed particles, and no blocky hydrate aggregates appeared, indicating that the composite inhibitor provided in this embodiment can significantly inhibit the aggregation of hydrate particles.

[0080] Example 3

[0081] The preparation of the hydrate inhibitor in this example is the same as that in Example 1.

[0082] According to the experimental conditions of Comparative Example 3, the composite hydrate inhibitor provided in this example was added before stirring, and the added mass was 1.61% of the mass of the oil phase. The same experimental method was used to evaluate the effect of the inhibitor.

[0083] Since an asphaltene-based hydrate inhibitor was added to the system, although the movement speed of the metal ball decreased after the hydrate was generated, it still kept reciprocating motion within 60 minutes, indicating that the composite inhibitor provided in this example can significantly inhibit the aggregation of hydrate particles.

[0084] Example 4

[0085] (1) Asphaltene (properties shown in Table 1) was dispersed in toluene by ultrasonic oscillation, the oscillation time was 30 min, the temperature was 50 °C, and the oscillation frequency was 40 MHz, and then hydrolyzed polymaleic anhydride and diisopropylbenzene peroxide were added, wherein the mass ratio of asphaltene, hydrolyzed polymaleic anhydride, diisopropylbenzene peroxide and toluene was 1:0.5:0.04:40, and the mixture was treated under stirring at a stirring rate of 300 rpm, a treatment time of 4 h, and a treatment temperature of 60 °C to obtain a pretreated asphaltene mixture;

[0086] (2) The pretreated asphaltene mixture obtained in step (1) was mixed with polyethyleneimine (molecular weight 10,000) and Span80 in a mass ratio of 40:0.04:0.8 at a stirring rate of 600 rpm, a stirring temperature of 40° C., and a stirring time of 20 min to obtain a hydrate inhibitor.

[0087] According to the experimental conditions of Comparative Example 2, the composite hydrate inhibitor provided in this example was added when preparing the emulsion, and the added mass was 2.03% of the mass of the oil phase. The evaluation experiment was carried out using the same experimental method using a high-pressure stirred hydrate reactor.

[0088] Since an asphaltene-based hydrate inhibitor was added to the system, the stirring paddle could be directly restarted smoothly after stopping stirring for 1 hour. After turning off the stirring paddle and releasing the pressure, it was observed that the hydrate in the autoclave existed in the form of dispersed particles, indicating that the composite inhibitor provided in this embodiment can significantly inhibit the aggregation of hydrate particles and has a significant inhibitory effect.

[0089] Example 5

[0090] The preparation of the hydrate inhibitor in this example is the same as that in Example 4.

[0091] According to the experimental conditions of Comparative Example 3, the composite hydrate inhibitor provided in this example was added before stirring, and the added mass was 2.03% of the mass of the oil phase. The same experimental method was used to evaluate the effect of the inhibitor.

[0092] Since an asphaltene-based hydrate inhibitor is added to the system, although the movement speed of the metal ball decreases after the hydrate is generated, it can still reciprocate without stopping within 60 minutes. This shows that the inhibitor provided in this embodiment can significantly inhibit the aggregation of hydrate particles, has a significant inhibitory effect, and can avoid pipeline blockage.

[0093] Example 6

[0094] (1) Asphaltene (properties shown in Table 1) was dispersed in o-xylene by ultrasonic oscillation, the oscillation time was 40 min, the temperature was 40 °C, and the oscillation frequency was 40 MHz, and then hydrolyzed polymaleic anhydride and diisopropylbenzene peroxide were added, wherein the mass ratio of asphaltene, hydrolyzed polymaleic anhydride, azobisisobutyronitrile and o-xylene was 1:0.5:0.08:25, and the mixture was treated under stirring at a stirring rate of 600 rpm, a treatment time of 4 h, and a treatment temperature of 60 °C to obtain a pretreated asphaltene mixture;

[0095] (2) The pretreated asphaltene mixture obtained in step (1) was mixed with polyvinyl alcohol (molecular weight 20,000) and Span80 in a mass ratio of 40:0.08:0.4 at a stirring rate of 500 rpm, a stirring temperature of 40° C., and a stirring time of 30 min to obtain a hydrate inhibitor.

[0096] According to the experimental conditions of Comparative Example 3, the composite hydrate inhibitor provided in this example was added before stirring, and the added mass was 3.27% of the mass of the oil phase. The same experimental method was used to evaluate the effect of the inhibitor.

[0097] Since an asphaltene-based hydrate inhibitor was added to the system, although the movement speed of the metal ball decreased after the hydrate was generated, it could still reciprocate within 60 minutes without stopping. This shows that the inhibitor provided in this embodiment can significantly inhibit the aggregation of hydrate particles, has a significant inhibitory effect, and can avoid pipeline blockage.

[0098] Comparative Example 4

[0099] The method for preparing the hydrate inhibitor in this comparative example is different from that in Example 1, except that Span 20 is not added in step (2).

[0100] According to the experimental conditions of Comparative Example 1, the hydrate inhibitor was added before stirring, and the mass of the inhibitor added was 1.61% of the mass of the oil phase. The same experimental method was used to observe the water droplet size of the oil-water system.

[0101] Observation results such as Figure 2 As shown, by comparing with the experimental results in Example 1, the water droplet size is larger.

[0102] Comparative Example 5

[0103] The method for preparing the hydrate inhibitor in this comparative example is different from that in Example 1, except that Span 20 is not added in step (2).

[0104] According to the experimental conditions of Comparative Example 2, the hydrate inhibitor was added before stirring, and the mass of the inhibitor added was 1.61% of the mass of the oil phase. The same experimental method was used to evaluate the hydrate aggregation.

[0105] After stopping stirring for 1 hour, the stirring paddle can be slowly restarted. After closing the stirring paddle and releasing the pressure, it is observed that the hydrate in the autoclave exists in the form of broken blocks, which is easier to aggregate into blocks than the hydrate in Example 2.

[0106] Comparative Example 6

[0107] The method for preparing the hydrate inhibitor in this comparative example is different from that in Example 1, except that Span 20 is not added in step (2).

[0108] According to the experimental conditions of Comparative Example 3, the hydrate inhibitor was added before stirring, and the added mass of the inhibitor was 1.61% of the mass of the oil phase. The same experimental method was used to evaluate the hydrate aggregation effect.

[0109] The results show that the movement speed of the balls decreases rapidly after the hydrate is generated, and the movement stops after running for 13 minutes. By comparing with Example 3, it can be seen that the hydrate in this comparative example is more likely to aggregate and block the pipeline.

[0110] Comparative Example 7

[0111] The preparation method of the hydrate inhibitor in this comparative example is different from that in Example 1 in that the asphaltene is not pretreated, and in step (2), the asphaltene is directly mixed with polyethyleneimine (molecular weight 8000) and Span20 in a mass ratio of 40:0.05:0.5.

[0112] According to the experimental conditions of Comparative Example 2, the hydrate inhibitor was added before stirring, and the added mass of the inhibitor was 1.61% of the mass of the oil phase. The same experimental method was used to evaluate the hydrate aggregation effect.

[0113] After stopping stirring for 1 hour, the stirring paddle can be slowly restarted. After closing the stirring paddle and releasing the pressure, it is observed that the hydrate in the autoclave exists in the form of broken blocks, which is easier to aggregate into blocks than the hydrate in Example 2.

[0114] Comparative Example 8

[0115] The method for preparing the hydrate inhibitor in this comparative example is different from that in Example 1, except that maleic anhydride is not added in step (1) when preparing the pretreated asphaltene mixture.

[0116] According to the experimental conditions of Comparative Example 2, the hydrate inhibitor was added before stirring, and the added mass of the inhibitor was 1.61% of the mass of the oil phase. The same experimental method was used to evaluate the hydrate aggregation effect.

[0117] The results showed that the stirring paddle could be slowly restarted 1 h after stopping stirring. After the stirring paddle was turned off and the pressure was released, the hydrate in the autoclave was observed to exist in the form of broken blocks.

[0118] Table 1 Properties of asphaltene used in the examples

[0119] Molecular weight 3180 Carbon content / wt% 82.8 Nitrogen content / wt% 1.9 Hydrogen content / wt% 7.7 Sulfur content / wt% 5.4 Oxygen content / wt% 2.2 Hydrogen-carbon molar ratio 1.11

[0120] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A hydrate inhibitor, characterized in that: The hydrate inhibitor comprises: a pre-treated asphaltene mixture, an active treatment agent and a synergist. The pre-treated asphaltene mixture comprises asphaltene, an anhydride treatment agent, a reaction initiator and a dissolving dispersant.

2. The hydrate inhibitor according to claim 1, characterized in that: The mass ratio of the pretreated asphaltene mixture, the active treatment agent and the synergist is 40:(0.01-0.1):(0.1-1).

3. The hydrate inhibitor according to claim 1, characterized in that: In the pretreated asphaltene mixture, the mass ratio of asphaltene, anhydride treating agent, reaction initiator and dissolving dispersant is 1: (0.1-0.5): (0.01-0.05): (5-50).

4. The hydrate inhibitor according to claim 1, characterized in that: The properties of the asphaltene include: a molecular weight of 500 to 8000, preferably 1000 to 5000; a carbon element mass content of 80wt% to 88wt%; a nitrogen element mass content of 0.5wt% to 2.5wt%; a hydrogen element mass content of 4wt% to 12wt%; a sulfur element mass content of 1.0wt% to 8.0wt%; an oxygen element mass content of 0.5wt% to 5.0wt%; and a hydrogen-carbon molar ratio of 1.0 to 1.5, preferably 1.0 to 1.

2.

5. The hydrate inhibitor according to claim 1, characterized in that: The acid anhydride treating agent is one or more of maleic anhydride, polyisobutylene succinic anhydride, dodecenyl succinic anhydride, tung oil anhydride, polyazelaic anhydride, polyglutaric anhydride, polyoxalic anhydride or hydrolyzed polymaleic anhydride; And / or, the reaction initiator is one or more of dicumyl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, sodium pyrosulfite, azobisisobutyronitrile or azobisisoheptanenitrile; And / or, the dissolving and dispersing agent is one or more of toluene, benzene, xylene, carbon disulfide, chloroform, carbon tetrachloride and methylnaphthalene.

6. The hydrate inhibitor according to claim 1, characterized in that: The active treatment agent is one or more of polyvinyl alcohol with a molecular weight of 10,000 to 150,000 or polyethyleneimine with a molecular weight of 1,000 to 10,000.

7. The hydrate inhibitor according to claim 1, characterized in that: The synergist is one or more of the non-ionic surfactants Span20, Span40, Span60 or Span80.

8. The method for preparing the hydrate inhibitor according to any one of claims 1 to 7, comprising the following steps: (1) dispersing asphaltene in a dissolving dispersant, adding an anhydride treating agent and a reaction initiator, and treating under stirring to obtain a pretreated asphaltene mixture; (2) The pretreated asphaltene mixture obtained in step (1) is mixed with an active treatment agent and a synergist, and stirred to obtain a hydrate inhibitor.

9. The method according to claim 8, characterized in that: In step (1), ultrasonic vibration is used to dissolve and disperse the asphaltene in the dissolving and dispersing agent; the vibration time is 30 minutes to 60 minutes, the temperature is 25° C. to 60° C., and the vibration frequency is 20 to 40 MHz.

10. The method according to claim 8, characterized in that: In step (1), the stirring rate is 100-800 rpm; the treatment time is 3-5 hours, and the treatment temperature is 60° C.-90° C.

11. The method according to claim 8, characterized in that: In step (2), the stirring rate is 200 rpm to 800 rpm, the stirring temperature is 25° C. to 60° C., and the stirring time is 10 min to 30 min.

12. Use of the hydrate inhibitor according to any one of claims 1 to 7 or the hydrate inhibitor prepared by the method according to any one of claims 8 to 11 in an oil-water system.

13. The use according to claim 12, characterized in that: The added mass of the hydrate inhibitor is 0.5% to 3.5% of the mass of the oil phase in the oil-water system.

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