Novel bifunctional hydrate inhibitor and preparation method thereof

Abstract

The invention discloses a bifunctional hydrate kinetic inhibitor with the average number-average molecular weight of 1000-10000 as shown in the formula I. The bifunctional hydrate kinetic inhibitor is an amphiphilic block copolymer, and compared with a common traditional inhibitor, the bifunctional hydrate kinetic inhibitor has the advantages of higher supercooling degree, better inhibition effect, smaller dosage and higher stability. The polymer has a general mass concentration of about 0.1-0.5 wt%, has anti-aggregation performance, can prevent aggregation of formed hydrates and reduce the risk of blockage, is suitable for an oil-gas-water three-phase or oil-water or gas-water two-phase coexistence system, is applied to inhibition of generation of hydrates in oil-gas exploitation, processing and transportation processes, and has a wide application prospect. # imgabs0 # R1 is (CH2) m1, m1 is an integer, and m1 is equal to 1 to 5; r2 is (CH2) m2, m2 is an integer, and m2 is equal to 1-4; m and n are integers, m is equal to 10-50, and n is equal to 10-200.

Description

Technical field:

[0001] The present invention relates to the technical field of hydrate inhibitors, and in particular to a novel bifunctional hydrate inhibitor and a preparation method thereof. Background technology:

[0002] Natural gas hydrate is a non-stoichiometric cage-type complex with an ice-like appearance. The formation of gas hydrates during natural gas transportation and processing can bring a series of hazards, such as blocking gas transmission pipelines, blocking blowout preventers and endangering deep-sea mining platform facilities, and even in extreme cases causing pipeline ruptures, resulting in huge casualties, economic losses, and environmental damage. Therefore, how to effectively prevent the formation of hydrates and avoid flow safety accidents caused by hydrate blockage is a very important and urgent issue for the entire oil and gas industry.

[0003] At present, injecting additives into pipelines is a relatively effective and economical method for preventing and controlling hydrates. These chemical additives are therefore also called hydrate inhibitors. Thermodynamic inhibitors (THIs) prevent the formation of hydrates by changing the thermodynamic conditions of hydrate formation, such as lowering the hydrate formation temperature or increasing the formation pressure. They can disrupt the hydrogen bonding effect of hydrate formation. However, the injection amount of THIs needs to reach 10%-50% to be effective, which is not only costly but also seriously damages the environment. In addition, THIs are usually volatile and enter oil and gas to increase refining costs and chemical losses. Based on environmental, technical and economic considerations, THIs are gradually replaced by new low-dose hydrate inhibitors (including kinetic inhibitors and anti-agglomeration agents).

[0004] Anti-agglomeration agents (AAs) achieve the purpose of hydrate prevention and control by dispersing hydrate particles and preventing them from aggregating, allowing them to exist in the pipeline in a flowable slurry state. However, due to the limited dispersibility and toxicity of AAs to the environment, their industrial application is limited. Kinetic inhibitors do not change the thermodynamic conditions for hydrate formation, but by delaying or preventing the nucleation or growth of hydrates, they ensure that the pipeline fluid has enough time to pass through the hydration zone, thereby achieving an inhibitory effect.

[0005] Kinetic inhibitors are usually water-soluble polymers, some of which have been put into industrial application, including polyvinyl pyrrolidone (PVP) and polyvinyl caprolactam (PVCap), and are often used as a standard for evaluating the performance of other inhibitors. Although they can effectively inhibit the formation or growth of hydrates, their application is not widespread. The reasons are: 1. They are not suitable for highly supercooled environments 2. After the hydrates are generated, they cannot effectively prevent the hydrates from agglomerating. Therefore, modifying them to improve their inhibitory and anti-agglomeration properties is a problem that needs to be solved urgently. The applicant's previous research results CN 118165155 A discloses that a new hydrate kinetic inhibitor is an amphiphilic block copolymer, and the new hydrate kinetic inhibitor is polymerized by an alkyl amide hydrophilic segment and a lactone / lactide hydrophobic segment; the molar ratio of the alkyl amide to the lactone / lactide monomer used to synthesize the new hydrate kinetic inhibitor is 1:1, and the new hydrate kinetic inhibitor has an average molecular weight Mn of 1000 to 10000; the new hydrate kinetic inhibitor has the following structure: But there is room for further improvement. Summary of the invention:

[0006] The purpose of the present invention is to provide a novel bifunctional hydrate inhibitor and a preparation method thereof.

[0007] The present invention is achieved through the following technical solutions:

[0008] The bifunctional hydrate kinetic inhibitor with an average number average molecular weight of 1000 to 10000 shown in Formula I is:

[0009]

[0010] Among them, R 1 for (CH 2 )m 1 , m1 is an integer, m1 = 1 to 5; R 2 for (CH 2 )m 2 , m2 is an integer, m2=1~4; m and n are integers, m=10~50, n=10-200.

[0011] The bifunctional hydrate kinetic inhibitor is an amphiphilic block copolymer, including a hydrophilic lactam polymer segment and a hydrophobic lactone / lactide polymer segment, wherein the hydrophilic lactam polymer segment and the hydrophobic lactone / lactide polymer segment are connected by The molar ratio of the lactam monomer to the lactone / lactide monomer for synthesizing the bifunctional hydrate kinetic inhibitor is 1:1-4.

[0012] The method for preparing the bifunctional hydrate kinetic inhibitor comprises the following steps:

[0013] 1) dissolving a vinyl lactam monomer, a chain initiator azobisisobutyronitrile and mercaptoethanol in a solvent by stirring, reacting at 30-90° C. for 6-40 hours in a nitrogen atmosphere, drying by rotary evaporation, and cooling to room temperature; dissolving the obtained product in tetrahydrofuran, precipitating with n-hexane, washing the obtained precipitate with a large amount of anhydrous ether, filtering and drying to obtain a terminal hydroxyl-modified polyvinyl lactam;

[0014] 2) The terminal hydroxyl-modified polyvinyl lactam, lactone / lactide and stannous octoate catalyst are stirred and dissolved in a solvent, reacted at 110-130° C. in a nitrogen atmosphere for 6-40 hours, then the reaction solution is dried by rotary evaporation, cooled to room temperature, the obtained product is dissolved in tetrahydrofuran, and then precipitated with n-hexane, the obtained precipitate is washed with a large amount of anhydrous ether, filtered and dried to obtain a new inhibitor; the molar ratio of the lactam monomer to the lactone / lactide monomer for synthesizing the bifunctional hydrate kinetic inhibitor is 1:1-4.

[0015] Preferably, in step 1), the amount of the chain initiator used accounts for 0.5 wt% to 2.0 wt% of the amount of the solvent used, the amount of the solvent used is 1 to 20 times the volume of the vinyl lactam monomer, and the solvent is isopropanol.

[0016] Preferably, in steps 1) and 2), the amount of n-hexane used is 2 to 10 times the volume of tetrahydrofuran.

[0017] Preferably, in step 2), the amount of stannous octoate used accounts for 0.5wt% to 2.0wt% of the amount of solvent used, the amount of solvent used is 1-20 times the volume of the vinyl lactam monomer, and the solvent is toluene.

[0018] The present invention also protects the use of the bifunctional hydrate kinetic inhibitor, which is used to inhibit the formation of hydrates in an oil-gas-water three-phase system, an oil-water or gas-water two-phase system. When used, it is first prepared into an aqueous solution, the concentration of the bifunctional hydrate kinetic inhibitor is 0.1wt% to 0.5wt%, the applicable pressure is 1 to 25MPa, and the temperature is -25 to 25°C.

[0019] The beneficial effects of the present invention are as follows: the present invention is a new type of bifunctional hydrate inhibitor, which has higher supercooling and better inhibition effect than general traditional inhibitors, and is used in smaller amounts, with a general mass concentration of about 0.1 to 0.5 wt%. It also has anti-aggregation properties, can prevent the aggregation of formed hydrates, and reduce the risk of blockage. The amount added is much smaller than that of traditional thermodynamic inhibitors, and the reagent cost is greatly reduced. It is suitable for oil-gas-water three-phase or oil-water or gas-water two-phase coexistence systems, and is used to inhibit the formation and aggregation of hydrates during oil and gas extraction, processing and transportation, and has broad application prospects. Description of the drawings:

[0020] Figure 1This is an example diagram of the time-temperature and time-pressure curves during the hydrate formation process in Example 1 of the present invention, 0.5wt% PVCAP-b-PVL solution.

[0021] Figure 2 This is an example diagram of the time-torque curve during the hydrate formation process in Example 1 of the present invention, 0.5wt% PVCAP-b-PVL solution. Specific implementation method:

[0022] The following is a further description of the present invention, rather than a limitation of the present invention.

[0023] The experimental equipment of the present invention is a visualized high-pressure stirring test device, and its main components include a sapphire high-pressure reactor, a mechanical stirrer, a torque detector, a low-temperature air bath, a temperature and pressure sensor, a vacuum pump, a high-pressure gas cylinder and a data acquisition instrument. The maximum working pressure of the sapphire high-pressure reactor is 11MPa, and the working temperature range is -30 to 80°C. The pressure in the sapphire high-pressure reactor can be freely adjusted by a gas valve. The low-temperature air bath can provide a temperature environment of -30 to 80°C for the jacket of the high-pressure reactor. The data acquisition system collects and stores parameters such as pressure, temperature, torque, and speed in the reactor in real time. The formation of hydrates can be judged or directly observed by the sudden change of temperature or pressure during the reaction. After the reaction starts, the pressure in the reactor drops suddenly, that is, the point where the pressure decrease trend deviates from the original trend is the starting point of hydrate formation, and the maximum supercooling is the temperature corresponding to this point minus the thermodynamic equilibrium temperature of the hydrate corresponding to this pressure. Constant stirring rate, when the temperature in the sapphire high-pressure reactor is constant, start to introduce methane gas until the pressure in the reactor is the set value and close the air inlet valve. Then, the temperature in the reactor is lowered to below the hydrate formation temperature at the pressure at a constant cooling rate (e.g. 1°C / h). The maximum supercooling that the solution can withstand is the hydrate formation temperature in this process minus the corresponding thermodynamic equilibrium temperature. The effect of the new inhibitor can be quantified based on the maximum supercooling that the solution with the inhibitor added can withstand. The greater the maximum supercooling, the better the inhibitory effect.

[0024] The anti-aggregation experimental equipment is the above-mentioned visualized high-pressure stirring test device, which uses a motor for high-intensity stirring and is equipped with a torque detector. First, the reactor is cooled to the experimental temperature and a certain amount of methane gas is introduced. Then, the temperature is maintained and stirring is started until hydrates begin to form. At this time, the pressure drops and the torque increases. The longer the time for hydrates to begin to form, the better the inhibitor effect. The smaller the torque after hydrate formation, the better the anti-aggregation effect of the inhibitor.

[0025] Specific implementation process:

[0026] Before the experiment is run, the reactor is repeatedly cleaned with deionized water three to five times, and then the reactor and experimental piping system are purged with nitrogen to ensure that the system is dry. The reactor is evacuated and 40mL (about 1 / 3 of the volume of the sapphire reactor) of deionized water or a new inhibitor solution is inhaled. In order to exclude the air in the reactor, 1MPa of methane gas with a purity of 99.99% is first introduced, and then vacuumed again, and this is repeated 3 times. The constant stirring rate is 800rpm. When the temperature in the sapphire high-pressure reactor is 20°C, methane gas is introduced until the pressure in the reactor is constant at 10.0MPa, and the air inlet valve is closed. Then, the temperature in the reactor is reduced from 20°C to -10°C at a cooling rate of 1°C / h. The temperature-pressure change curve is used to determine whether hydrates are generated.

[0027] Before the anti-aggregation experiment is run, the reactor is repeatedly cleaned with deionized water three to five times, and then the reactor and experimental pipeline system are purged with nitrogen to ensure that the system is dry. The reactor is evacuated and 40mL (about 1 / 3 of the volume of the sapphire reactor) of oil-water mixed solution (the oil-water ratio is 7 / 3, and the concentration of the inhibitor is 0-0.5% of the volume of the water phase) is inhaled. In order to exclude the air in the reactor, 1MPa of methane gas with a purity of 99.99% is first introduced, and then vacuumed again, and this is repeated 3 times. The constant stirring rate is 800rpm. When the temperature in the sapphire high-pressure reactor is 3°C, methane gas is introduced until the pressure in the reactor is constant at 8.0MPa, and the air inlet valve is closed. Then, mechanical stirring is turned on, the speed is set to 800rpm, and the temperature in the reactor is maintained at 3°C. Observe the changes in air pressure and torque to determine whether hydrates are generated.

[0028] Example 1: Preparation of amphiphilic block copolymer hydrate kinetic inhibitor PVCAP-b-PVL

[0029] The PVCAP-b-PVL structure is shown below:

[0030]

[0031] The following steps are involved:

[0032] 0.719mmol of chain initiator azobisisobutyronitrile, 71.9mmol of vinyl caprolactam, and 3.6mmol of mercaptoethanol were weighed in sequence and dissolved in 100mL of isopropanol and added to a 250mL three-necked flask, stirred until dissolved, sealed with a rubber stopper, vacuumed and passed nitrogen three times, and then reacted at 85°C in a nitrogen atmosphere for 20 hours; the reaction solution was dried by rotary evaporation at 50°C and cooled to room temperature. The obtained product was dissolved in tetrahydrofuran and then precipitated with n-hexane. The obtained precipitate was washed with a large amount of anhydrous ether, filtered and dried to obtain terminal hydroxyl-modified polyethylene caprolactam.

[0033] Weigh 1mmol of terminal hydroxyl-modified polyethylene caprolactam, 1mmol of γ-valerolactone, and 10mmol of stannous octoate and dissolve them in toluene, add them to a 250mL three-necked flask, stir until dissolved, seal with a rubber stopper, evacuate and pass nitrogen three times; react at 110°C in a nitrogen atmosphere for 24 hours; dry the reaction solution by rotary evaporation and cool to room temperature. The obtained product is dissolved in tetrahydrofuran and then precipitated with n-hexane. The obtained precipitate is washed with a large amount of anhydrous ether, filtered and dried to obtain a new inhibitor.

[0034] Detection and measurement: The above inhibitors were prepared into 0.1wt%, 0.25wt%, and 0.5wt% aqueous solutions, and the maximum supercooling degree of hydrate formation in the inhibitor-containing system and the maximum torque during the hydrate formation process were measured. The experimental results are shown in Table 4.

[0035] The gel permeation chromatography (GPC) data of the new bifunctional hydrate inhibitor PVCAP-b-PVL are shown in Table 1:

[0036] Table 1 Number average molecular weight and polydispersity index

[0037]

[0038] Example 2: Preparation of amphiphilic block copolymer hydrate kinetic inhibitor PVP-b-PVL

[0039] The structure of PVP-b-PVL is shown below

[0040]

[0041] The preparation method thereof is similar to that of Example 1, except that the hydrophilic monomer vinyl caprolactam is replaced by vinyl pyrrolidone. The gel permeation chromatography (GPC) data of the obtained novel bifunctional hydrate inhibitor PVP-b-PVL are shown in Table 2.

[0042] Table 2 Number average molecular weight and polydispersity index

[0043]

[0044] Detection and measurement: The above inhibitors were prepared into 0.1wt%, 0.25wt%, and 0.5wt% aqueous solutions, and the maximum supercooling degree of hydrate formation and the maximum torque during hydrate formation in the inhibitor-containing system were measured. The experimental results are shown in Table 4.

[0045] Comparative Example 1: Preparation of unmodified polyvinyl caprolactam (PVCAP)

[0046] The following steps are involved:

[0047] Weigh 0.719mmol of chain initiator azobisisobutyronitrile, 71.9mmol of vinyl caprolactam, and 100mL of isopropanol solvent in a 250mL three-necked flask, stir until dissolved, seal with a rubber stopper, evacuate and pass nitrogen three times; react at 85°C in a nitrogen atmosphere for 20 hours; dry the reaction solution by rotary evaporation at 50°C, and cool to room temperature. The obtained product is dissolved in tetrahydrofuran and then precipitated with n-hexane. The obtained precipitate is washed with a large amount of anhydrous ether, filtered, and dried to obtain PVCAP.

[0048] Detection and measurement: The above inhibitors were prepared into aqueous solutions with concentrations of 0.1wt%, 0.25wt%, and 0.5wt%, and the maximum supercooling degree of hydrate formation in the inhibitor-containing system and the maximum torque during hydrate formation were measured. The experimental results are shown in Table 4.

[0049] Comparative Example 2:

[0050] Pure water was added into the reactor to determine the maximum supercooling degree of hydrate formation in the additive-free system and the maximum torque of the hydrate formation process.

[0051] Comparative Example 3:

[0052] Preparation of amphiphilic block copolymer (PMAM-b-PCL)

[0053] The preparation method thereof is as described in Example 1, except that the hydrophilic monomer vinyl caprolactam is replaced by methacrylamide, and γ-valerolactone is replaced by ε-caprolactone.

[0054] The following steps are involved:

[0055] 0.719mmol of chain initiator azobisisobutyronitrile, 71.9mmol of methacrylamide, and 3.6mmol of mercaptoethanol were weighed in sequence and dissolved in 100mL of isopropanol and added to a 250mL three-necked flask, stirred until dissolved, sealed with a rubber stopper, vacuumed and passed nitrogen three times, and then reacted at 85°C in a nitrogen atmosphere for 20 hours; the reaction solution was dried by rotary evaporation at 50°C and cooled to room temperature. The obtained product was dissolved in tetrahydrofuran and then precipitated with n-hexane. The obtained precipitate was washed with a large amount of anhydrous ether, filtered and dried to obtain terminal hydroxyl-modified polymethacrylamide.

[0056] Weigh 1mmol of terminal hydroxyl-modified polymethacrylamide, 1mmol of ε-caprolactone, and 10mmol of stannous octoate and dissolve them in toluene, add them to a 250mL three-necked flask, stir until dissolved, seal with a rubber stopper, evacuate and pass nitrogen three times; react at 110°C in a nitrogen atmosphere for 24 hours; dry the reaction solution by rotary evaporation and cool to room temperature. The obtained product is dissolved in tetrahydrofuran and then precipitated with n-hexane. The obtained precipitate is washed with a large amount of anhydrous ether, filtered and dried to obtain a new inhibitor.

[0057] The gel permeation chromatography (GPC) data of the novel hydrate kinetic inhibitor PMAM-b-PCL are shown in Table 3:

[0058] Table 3 Number average molecular weight and polydispersity index

[0059]

[0060] Detection and determination: The above inhibitors were prepared into aqueous solutions with concentrations of 0.25 wt%, 0.5 wt% and 1 wt% to determine the maximum supercooling degree of hydrate formation in the inhibitor-containing system. The experimental results are shown in Table 4.

[0061] Table 4 Comparison of concentration, maximum supercooling temperature and maximum torque

[0062]

[0063]

[0064] The above specific embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make modifications to the embodiments without any creative contribution as needed. However, such modifications are protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A bifunctional hydrate kinetic inhibitor having an average number average molecular weight of 1000 to 10000 as shown in Formula I: in, R1 is (CH2)m1, m1 is an integer, m1=1-5; R2 is (CH2)m2, m2 is an integer, m2=1-4; m and n are integers, m=10-50, n=10-200.

2. The method for preparing the bifunctional hydrate kinetic inhibitor according to claim 1, characterized in that: The following steps are involved: 1) dissolving a vinyl lactam monomer, a chain initiator azobisisobutyronitrile and mercaptoethanol in a solvent by stirring, reacting at 30-90° C. for 6-40 hours in a nitrogen atmosphere, drying by rotary evaporation, and cooling to room temperature; dissolving the obtained product in tetrahydrofuran, precipitating with n-hexane, washing the obtained precipitate with a large amount of anhydrous ether, filtering and drying to obtain a terminal hydroxyl-modified polyvinyl lactam; 2) The terminal hydroxyl-modified polyvinyl lactam, lactone / lactide and stannous octoate catalyst are stirred and dissolved in a solvent, reacted at 110-130° C. in a nitrogen atmosphere for 6-40 hours, then the reaction solution is dried by rotary evaporation, cooled to room temperature, the obtained product is dissolved in tetrahydrofuran, and then precipitated with n-hexane, the obtained precipitate is washed with a large amount of anhydrous ether, filtered and dried to obtain a new inhibitor; the molar ratio of the lactam monomer to the lactone / lactide monomer for synthesizing the bifunctional hydrate kinetic inhibitor is 1:1-4.

3. The method for preparing a bifunctional hydrate kinetic inhibitor according to claim 2, characterized in that: In step 1), the amount of the chain initiator used accounts for 0.5wt% to 2.0wt% of the amount of the solvent used, the amount of the solvent used is 1-20 times the volume of the vinyl lactam monomer, and the solvent is isopropanol.

4. The method for preparing a bifunctional hydrate kinetic inhibitor according to claim 2, characterized in that: In steps 1) and 2), the amount of n-hexane used is 2 to 10 times the volume of tetrahydrofuran.

5. The method for preparing a bifunctional hydrate kinetic inhibitor according to claim 2, characterized in that: Step 2) the amount of stannous octoate used accounts for 0.5wt% to 2.0wt% of the amount of solvent used, the amount of solvent used is 1 to 20 times the volume of the vinyl lactam monomer, and the solvent is toluene.

6. The use of the bifunctional hydrate kinetic inhibitor according to claim 1, characterized in that: It is used to inhibit the formation of hydrates in oil-gas-water three-phase system, oil-water or gas-water two-phase system.

7. The use of the bifunctional hydrate kinetic inhibitor according to claim 6, characterized in that: When used, it is first prepared into an aqueous solution, the concentration of the bifunctional hydrate kinetic inhibitor is 0.1wt% to 0.5wt%, the applicable pressure is 1 to 25MPa, and the temperature is -25 to 25°C.

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