A fatty acid amide propyl dimethylamine hydrate inhibitor and its application

Abstract

The present invention provides a fatty acid amide propyl dimethylamine hydrate inhibitor, including fatty acid amide propyl dimethylamine, wherein the fatty acid amide propyl dimethylamine has a general structural formula as shown in Formula I, wherein R in Formula I is a saturated hydrocarbon group with a carbon number of 1 to 18 or an unsaturated hydrocarbon group with a carbon number of 1 to 22. Nanoparticles are also included, and the inhibitor is mainly compounded by fatty acid amide propyl dimethylamine and nanoparticles. Based on the same inventive concept, the present invention also provides an application of the fatty acid amide propyl dimethylamine hydrate inhibitor in the prevention and treatment of gas hydrates in deepwater oil and gas gathering and transportation pipelines. The present invention proposes a fatty acid amide propyl dimethylamine hydrate inhibitor, which can make the generated hydrate particles form a hydrate slurry and flow with the fluid in the pipeline without agglomerating into large blocks or depositing on the pipe wall. The present invention is applicable to the oil, gas and water three-phase coexistence system, and has the characteristics of wide applicability and low cost.

Description

Technical Field

[0001] The invention relates to the field of gas hydrate prevention and treatment in deepwater oil and gas gathering and transportation pipelines, and in particular to a fatty acid amide propyl dimethylamine hydrate inhibitor and application thereof, and also to a fatty acid amide propyl dimethylamine and nanoparticle compound as a composite hydrate inhibitor and application thereof. Background Art

[0002] Gas hydrates are ice-like crystals formed by small molecular gases (methane, ethane, propane, carbon dioxide, nitrogen, etc.) and water under high pressure and low temperature conditions. Water molecules and gas molecules are called host molecules and guest molecules respectively. The host water molecules form polyhedral cages under the action of hydrogen bonds, while the guest molecules fill the cages to form a stable structure. Oil and gas transportation is a key link in deepwater oil and gas development. Since the produced oil and gas also contain some water, they will react with natural gas under low temperature and high pressure. Therefore, natural gas hydrates are easily generated in deepwater mixed pipelines. These hydrates are difficult to transport over long distances. Instead, they gradually gather and deposit in the process of following the flow of oil, gas and water, and even form large-scale hydrate blockages, thereby affecting the transportation efficiency of oil and gas, threatening the safe production of oil and gas, and may cause huge economic losses. In view of the problems of hydrate generation, aggregation, and blockage in pipelines, the more feasible hydrate prevention and control methods include dehydration, pressure reduction, heating, and inhibitor injection, among which the most common is the inhibitor injection method. The inhibitor injection method mainly ensures pipeline flow safety from two aspects. By adding chemicals to the pipeline, one is to inhibit the nucleation and growth process of hydrates, so that the volume fraction of hydrates in the pipeline is kept at a low level; the other is to disperse the generated hydrates in the liquid phase in the form of small particles, thereby avoiding clogging the pipeline. According to the difference in the mode of action, hydrate inhibitors can be divided into three categories: thermodynamic inhibitors, kinetic inhibitors and polymerization inhibitors. Thermodynamic inhibitors require a large injection volume, are relatively expensive, and are easy to pollute the environment, making them unsuitable for promotion. Kinetic inhibitors and polymerization inhibitors are collectively referred to as low dosage hydrate inhibitors (LDHIs). A small amount of LDHIs (≤2wt%) can delay or prevent hydrate blockage. Kinetic inhibitors will fail at high supercooling and are less environmentally friendly.

[0003] Inhibitors are more effective at high supercooling, and inhibitors from natural products are environmentally friendly, so they have broad application prospects. On the basis of fully considering the advantages and disadvantages of various types of hydrate inhibitors, how to develop an efficient, economical and environmentally friendly hydrate inhibitor to prevent gas hydrates from clogging deepwater oil and gas gathering and transportation pipelines is a technical problem to be solved by the present invention. Summary of the invention

[0004] The purpose of the present invention is to provide a fatty acid amide propyl dimethylamine hydrate inhibitor and its application in view of the deficiencies of the prior art. Based on the above problems, the present invention proposes a fatty acid amide propyl dimethylamine hydrate inhibitor, which can make the generated hydrate particles form a hydrate slurry and flow with the fluid in the pipeline without agglomerating into large blocks or depositing on the pipe wall. The present invention is applicable to the oil, gas and water three-phase coexistence system, and has the characteristics of wide applicability and low cost.

[0005] The technical solution of the present invention is achieved in this way:

[0006] A fatty acid amide propyl dimethylamine hydrate inhibitor, comprising fatty acid amide propyl dimethylamine, wherein the fatty acid amide propyl dimethylamine has a general structural formula as shown in Formula I, wherein R in Formula I is a saturated hydrocarbon group having 1 to 18 carbon atoms or an unsaturated hydrocarbon group having 1 to 22 carbon atoms; preferably, R in Formula I is a saturated hydrocarbon group having 1 to 16 carbon atoms or an unsaturated hydrocarbon group having 1 to 21 carbon atoms;

[0007]

[0008]

[0009] The fatty acid amidopropyl dimethylamine of the present invention has a general structural formula as shown in Formula I, wherein RC(O) is a saturated and unsaturated fatty acid residue extracted from almond oil, avocado oil, babassu seed oil, rapeseed oil, coconut oil, mink oil, oat kernel oil, olive oil, sesame oil, soybean, sunflower oil, tall oil, animal fat, and germ oil. The fatty acid amidopropyl dimethylamine hydrophilic head group is combined with the hydrate surface, and the hydrophobic tail chain extends into the oil phase, and the hydrate particles are prevented from aggregating by the spatial repulsion between the hydrophobic tail chains.

[0010] A fatty acid amide propyl dimethylamine hydrate inhibitor as described above, wherein the fatty acid amide propyl dimethylamine is selected from any one of the following;

[0011] The fatty acid amide propyl dimethylamine is caprylic acid amide propyl dimethylamine, and the molecular formula is C 13 H 28 N2O, the structural formula is shown in Formula II,

[0012]

[0013] The fatty acid amide propyl dimethylamine is caprylic acid amide propyl dimethylamine, and the molecular formula is C 15 H 32 N2O, the structural formula is shown in Formula III,

[0014]

[0015] The fatty acid amide propyl dimethylamine is lauramide propyl dimethylamine, and the molecular formula is C 17 H 36 N2O, the structural formula is shown in Formula IV,

[0016]

[0017] The fatty acid amide propyl dimethylamine is oleic acid amide propyl dimethylamine, and the molecular formula is C 23 H 46 N2O, the structural formula is shown in Formula V,

[0018]

[0019] The fatty acid amide propyl dimethylamine is linoleic acid amide propyl dimethylamine, and the molecular formula is C 23 H 44 N2O, the structure is as shown in formula VI,

[0020]

[0021] The fatty acid amide propyl dimethylamine is ricinoleic acid amide propyl dimethylamine, and the molecular formula is C 23 H 46 N2O2, the structural formula is shown in formula VII,

[0022]

[0023] The fatty acid amide propyl dimethylamine is erucic acid amide propyl dimethylamine, and the molecular formula is C 27 H 54 N2O, the structural formula is shown in formula VIII,

[0024]

[0025] Preferably, the fatty acid amide propyl dimethylamine is selected from any one of caprylic acid amide propyl dimethylamine, caprylic acid amide propyl dimethylamine, lauryl amide propyl dimethylamine, oleic acid amide propyl dimethylamine, erucic acid amide propyl dimethylamine, and cocoamidopropyl dimethylamine. More preferably, the fatty acid amide propyl dimethylamine is selected from any one of lauryl amide propyl dimethylamine and cocoamidopropyl dimethylamine.

[0026] However, the applicant unexpectedly discovered that not all fatty acid amide propyl dimethylamines containing the structure of Formula I function as polymerization inhibitors. For example, stearic acid amide propyl dimethylamine, whose molecular formula is C 23 H 48 N2O, the structural formula is shown in Formula IX; another example is behenamidopropyl dimethylamine, the molecular formula of which is C 27 H 56N2O, with a structural formula as shown in Formula X, the above two fatty acid amide propyl dimethylamines do not have the performance of inhibitors. Therefore, among the numerous fatty acid amide propyl dimethylamine compounds, the inventors have made creative efforts to screen out the above compounds with excellent inhibitory properties.

[0027]

[0028] A fatty acid amide propyl dimethylamine hydrate inhibitor as described above, the mass fraction of the fatty acid amide propyl dimethylamine is 0.5wt% to 2wt% (based on the mass of the system water). In some embodiments of the present invention, the fatty acid amide propyl dimethylamine hydrate inhibitor contains only fatty acid amide propyl dimethylamine, and the mass fraction of the fatty acid amide propyl dimethylamine is 0.5wt% to 2wt% (based on the mass of the system water); more preferably, the mass fraction of the fatty acid amide propyl dimethylamine is 2wt% (based on the mass of the system water).

[0029] The fatty acid amide propyl dimethylamine hydrate polymerization inhibitor as described above also includes nanoparticles, and the polymerization inhibitor is mainly compounded by fatty acid amide propyl dimethylamine and nanoparticles.

[0030] A fatty acid amide propyl dimethylamine hydrate inhibitor as described above, the nanoparticles are prepared by silicon dioxide, ferric oxide, titanium dioxide, zinc oxide, ferric oxide or aluminum oxide, and the effective particle size range is 0-500nm. Preferably, the effective particle size of the nanoparticles is 20nm hydrophilic nano-SiO2 or hydrophobic nano-SiO2. The nanoparticles described in the present invention relate to hydrophilic nanoparticles and hydrophobic nanoparticles with two surface properties of hydrophilic and hydrophobic. The nanoparticles can be attached to the surface of oil-water-hydrate particles, stabilize the emulsion, and form a mass transfer barrier between the gas phase and the water phase between the hydrate particles to prevent the hydrate particles from aggregating.

[0031] A fatty acid amide propyl dimethylamine hydrate inhibitor as described above, the mass fraction of the fatty acid amide propyl dimethylamine is 0.5wt% to 2wt% (based on the mass of the system water), and the mass fraction of the nanoparticles is 0.1wt% to 0.5wt% (based on the mass of the system water). Preferably, in some other embodiments of the present invention, the inhibitor is mainly compounded by fatty acid amide propyl dimethylamine and nanoparticles, the mass fraction of the fatty acid amide propyl dimethylamine is 0.5wt% to 2wt% (based on the mass of the system water), and the mass fraction of the nanoparticles is 0.1wt% to 0.4wt% (based on the mass of the system water). Under this scheme, the fatty acid amide propyl dimethylamine is lauryl amide propyl dimethylamine or cocoamidopropyl dimethylamine, and the molecular formula of cocoamidopropyl dimethylamine is C 17 H 36N2O, structural formula as shown in formula Ⅺ, the nanoparticles are 20nm hydrophilic nano-SiO2 particles or 20nm hydrophobic nano-SiO2 particles; more preferably, the mass fraction of the fatty acid amide propyl dimethylamine is 0.5wt% (based on the mass of system water), and the mass fraction of the nanoparticles is 0.1wt% to 0.25wt% (based on the mass of system water). Under this scheme, the fatty acid amide propyl dimethylamine is preferably cocoamidopropyl dimethylamine, and the nanoparticles are preferably hydrophobic nano-SiO2 particles with a particle size of 20nm. Most preferably, the mass fraction of the fatty acid amide propyl dimethylamine is 0.5wt% (based on the mass of system water), and the mass fraction of the nanoparticles is 0.1wt% (based on the mass of system water). Under this scheme, the fatty acid amide propyl dimethylamine is preferably cocoamidopropyl dimethylamine, and the nanoparticles are preferably hydrophobic nano-SiO2 particles with a particle size of 20nm.

[0032]

[0033] Based on the same inventive concept, the present invention also provides an application of a fatty acid amide propyl dimethylamine hydrate inhibitor in the prevention and treatment of gas hydrates in deepwater oil and gas gathering and transportation pipelines.

[0034] The use of the fatty acid amide propyl dimethylamine hydrate inhibitor in the prevention and treatment of gas hydrates in deepwater oil and gas gathering and transportation pipelines is suitable for the oil, gas and water three-phase coexistence system, and the applicable range of water content is 20-80%.

[0035] Compared with the existing hydrate inhibitors, the present invention has the following advantages:

[0036] (1) Low dosage: The dosage concentration of conventional thermodynamic inhibitors in deepwater oil and gas gathering and transportation can be as high as 60wt% (based on the mass of water in the system), while the fatty acid amide propyl dimethylamine hydrate inhibitor of the present invention can completely prevent hydrate blockage at a concentration of only 0-2wt% (based on the mass of water in the system).

[0037] (2) High performance: Facing the complex conditions in deepwater oil and gas gathering and transportation pipelines, the present invention can still prevent the aggregation and blockage of hydrates under the condition of 20%-80% water content, and the compound inhibitor has stronger performance than a single inhibitor.

[0038] (3) Strong environmental friendliness: The fatty acid amide propyl dimethylamine of the present invention is prepared from natural fatty acids as raw materials. Some natural fatty acids have been widely used in the washing industry. This type of inhibitor has good biodegradability. In addition, compared with chemical surfactants, the nanoparticles of the present invention are completely non-toxic, non-polluting, and easier to recycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a standard diagram for classifying the inhibition levels of the present invention in a swing kettle;

[0040] Figure 2 is a graph showing changes in pressure, temperature, hydrate volume fraction and slider position over time in comparative example 1 of the present invention in a swing kettle;

[0041] Figure 3 is a graph showing changes in the hydrate volume fraction and the position of the slider over time in Comparative Example 2 of the present invention in a swing kettle;

[0042] Figure 4 is a graph showing changes in pressure, temperature, hydrate volume fraction and slider position over time in Example 3 of the present invention in a swing kettle;

[0043] Figure 5 It is an image of the change of the hydrate volume fraction and the slider position over time in the system of adding 0.5wt% lauramide propyl dimethylamine and 0.1wt% hydrophilic nano-SiO2 in Example 13 of the present invention in the swing kettle;

[0044] Figure 6 is an image of the displacement velocity of the slider in Example 13 of the present invention changing with the volume fraction of hydrate in the swing kettle;

[0045] Figure 7 This is an image of the relative current of Example 14 of the present invention changing with the hydrate volume fraction in a stirred tank. DETAILED DESCRIPTION

[0046] The following will combine the contents in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0048] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0049] The materials and reagents used in the following examples, if not otherwise specified, can all be obtained from commercial sources. Caprylic acid amidopropyl dimethylamine, caprylic acid amidopropyl dimethylamine, lauryl amide propyl dimethylamine, and cocamidopropyl dimethylamine were purchased from Shanghai Chuxing Chemical Co., Ltd., and stearic acid amidopropyl dimethylamine, behenyl amide propyl dimethylamine, oleic acid amidopropyl dimethylamine, and erucic acid amidopropyl dimethylamine were purchased from Hangzhou Molot Chemical Technology Co., Ltd., which are PKO type nonionic surfactants. Hydrophilic spherical nano-SiO2 and hydrophobic spherical nano-SiO2 were purchased from Shuangying Alloy Material Co., Ltd., and the particle size was 20nm.

[0050] The present invention adopts a high-pressure hydrate swing kettle experimental device and a high-pressure hydrate stirring kettle as experimental equipment for testing the performance of the polymerization inhibitor.

[0051] The high-pressure hydrate swing kettle experimental device is mainly composed of a kettle body, a swing system, a gas injection system, a data acquisition system and a temperature control system. The swing system consists of a two-phase stepper motor, a driver, a rotating shaft and a control box. The swing angle of the swing kettle is set to ±90°, and the maximum swing frequency is 1 time / minute; the gas injection system includes a vacuum pump, a high-pressure gas cylinder, a pressure reducing valve, a six-way valve and a gas pipeline; the data acquisition system includes all the software and hardware related to temperature, pressure and displacement data, including temperature sensors, pressure sensors, displacement sensors, data acquisition boxes and real-time monitoring software. The temperature sensor has a range of -50℃ to 100℃, with a measurement accuracy of ±0.1K, and the pressure sensor has a range of 0MPa to 40MPa, with an accuracy of ±0.01MPa. The displacement sensor has an operating temperature range of -40°C to 75°C, and a linearity of less than ±0.02% of the full scale. The monitoring software collects 4 position information per second to reflect the falling process of the slider. The temperature control system uses Ningbo Tianheng THX-2030H water bath with a temperature range of -20°C to 100°C and a cooling rate of 2°C·h -1 The formation and aggregation of hydrates directly affects the motion state of the slider. Combined with the characteristics of the swing kettle equipment, the classification standard of anti-agglomeration performance is proposed, such as Figure 1 shown.

[0052] Considering that the total length of the kettle is 200mm, the movable range of the slider is 10mm-200mm. It is stipulated that the slider movement range of 190mm is considered to be normal movement of the slider, and the slider movement range of 0mm is considered to be blocked. If the performance of the inhibitor is strong, the hydrate will be dispersed in the liquid phase after formation, and the slider will slide freely in the range of 10mm-200mm, but the hydrate particles will increase the fluid viscosity and reduce the displacement rate of the slider. The hydrate inhibition and performance can be evaluated by monitoring the movement rate of the slider; if the performance of the inhibitor is weak, the aggregated hydrates will be deposited on both sides of the kettle with the movement of the slider, resulting in a reduction in the movement range of the slider, but due to the effect of the inhibitor, the hydrate aggregation force is low and the slider can still move; if the performance of the hydrate inhibitor is poor, the deposited and aged hydrates will directly block the slider, and the slider will be stuck and have no displacement. Based on this, the inhibition performance is divided into three levels of A, B, and C from good to poor. Under the action of the inhibitor, the slider always moves normally throughout the experiment. The performance of this type of inhibitor is recorded as grade A. Figure 1 (c); During the whole experiment, hydrate aggregates precipitated, which reduced the range of motion of the slider, but there was no clogging. The performance of this type of inhibitor is recorded as Class B. Figure 1 (b); if the slider is blocked during the whole experiment, the performance of the inhibitor is C grade. Figure 1 (a). Using the monitored temperature and pressure data, the volume fraction of hydrate in the kettle can be calculated. The calculation method of the hydrate volume fraction is:

[0053]

[0054] Where V hyd represents the volume of the generated hydrate, in mL; V oil is the volume of white oil, mL; V water is the initial volume of water, mL; V water,conv is the volume of water converted to hydrate, mL.

[0055] For the evaluation of Class A inhibitors, it is not possible to compare the hydrate inhibition performance through the motion analysis of the slider. In order to further evaluate the inhibition effect of Class A inhibitors, the displacement rate of the slider was calculated to characterize the change in fluid viscosity caused by hydrate formation and aggregation in the system. The stronger the hydrate inhibitor, the smaller the hydrate particles generated in the system, the lower the fluid viscosity, and the smaller the displacement rate of the slider. The movement range of the slider from the bottom of the kettle to the top of the kettle is the displacement of the slider, recorded as L, and the time consumed by the displacement is recorded as Δt. The displacement rate of the slider is calculated as follows:

[0056]

[0057] Where L is the displacement of the slider, mm; Δt is the time of slider displacement, s; v is the displacement rate of the slider, mm·s-1 .

[0058] The inhibitory effect of the hydrate inhibitor designed by the present invention can be judged according to the final slider movement range and movement speed under the same hydrate volume fraction. Under the final hydrate volume fraction, the larger the final slider movement range, the higher the inhibitory performance level, which proves that the inhibitor has better performance. Under the same slider movement range, the strength of the inhibitory performance can be distinguished by comparing the slider movement speed. The larger the slider movement speed, the smaller the viscosity hindrance and the stronger the inhibitory performance. Before the experiment, open the end cover of the reactor, add petroleum ether to repeatedly clean the inner wall of the reactor, and dry it after washing. No. 5 white oil, deionized water and inhibitor are prepared into an oil-water mixture in a certain proportion and added to the reactor, tighten the end cover of the reactor, vacuum the reactor in turn until the gauge pressure value is stable, and set the water bath to 16°C. After the temperature in the reactor is stable, turn on the gas cylinder switch, the six-way valve and the reactor air inlet valve, and pass high-purity methane into the reactor. After reaching the experimental pressure, close the above switch and valve. Turn on the control box and the motor power supply, set the swing angle and swing frequency of the swing kettle on the control box, and the reactor starts to swing driven by the motor and the rotating shaft, and methane quickly dissolves in the white oil and water. The pressure in the reactor is stabilized at 8MPa, the water bath temperature is set to 0℃, and the temperature is lowered at a constant rate of 2℃ / h. At the same time, the data acquisition function is turned on to record the temperature, pressure, and position data during the hydrate formation process. The temperature and pressure are stable again, indicating that the hydrate formation is complete. Turn off the water bath and data acquisition, turn off the control box and the motor power supply, and slowly discharge the gas in the reactor through the exhaust port to prevent the liquid from entering the high-pressure hose due to a sudden drop in pressure. After the gas is exhausted, pour out the waste liquid in the reactor and the test is over.

[0059] The high-pressure stirred tank experimental device is mainly composed of a reactor body, a gas injection system, a temperature control system, a data acquisition system and a stirring system. The reactor has a volume of 1038 mL, is made of 316 stainless steel, and has a maximum operating pressure of 30 MPa. The gas injection system includes a gas cylinder, a booster pump, a vacuum pump, a gas pipeline and a valve. The gas is injected into the reactor through the pipeline and several valves. The temperature control system uses a THD-3030 water bath purchased from Changzhou Jintan Liangyou Instrument Co., Ltd., which can control the temperature range between -30°C and 100°C, with a temperature fluctuation range of ±0.05°C, a digital display resolution of 0.01, and a pump flow rate of 12L·min -1The data acquisition system includes a temperature sensor, a pressure sensor and a data recording software. A Pt100A-grade thermal resistor is used to monitor the temperature in the kettle in real time. The pressure sensor has an accuracy of ±0.25%. It is equipped with a current sensor to monitor the current data of the stirring motor. The data recording software can view and save the temperature, pressure and current data in the kettle in real time. The stirring system is realized by the motor driving the impeller to rotate, and the stirring paddle speed is 0-1200rpm. The test steps include: (1) repeatedly cleaning the stirring kettle with petroleum ether, and drying it after cleaning. (2) No. 5 white oil, deionized water and inhibitor are added to the stirring kettle according to a certain ratio, and the kettle is vacuumed. (3) Open the gas cylinder and the air inlet valve, inject the acidic mixed gas into the kettle to the experimental pressure, then close the gas cylinder, set the stirring kettle rotor speed to 300rpm, and set the water bath temperature to 16℃. (4) The gas quickly dissolves in the solution, and repeats step (2) until the temperature and pressure in the stirring kettle stabilize at the experimental temperature and pressure. (5) Set the water bath temperature to 0°C and cool the reactor at a constant rate. The experimental temperature after cooling is 2.5°C. Start recording the temperature, pressure and current data in the reactor. By analyzing the temperature, pressure, hydrate volume fraction and relative current in the experiment, determine the effect of the inhibitor on the fluidity of the hydrate slurry under different conditions, and thus evaluate the performance of the inhibitor.

[0060] During the experiment, the formation and aggregation of hydrates will increase the viscosity of the liquid phase. The greater the degree of hydrate aggregation, the higher the viscosity of the slurry, and the greater the torque on the stirring paddle, which is numerically reflected as the current value of the stirring motor. In order to eliminate the errors between different experiments as much as possible, the relative current is used to represent the change in fluid viscosity in the system. The relative current is obtained by the ratio of the real-time current to the initial current of the experiment. It is a dimensionless parameter. Therefore, the relative current value can be used to evaluate the performance of the hydrate inhibitor. The stronger the inhibitory performance, the smaller the relative current of the stirring motor. The expression of relative current is:

[0061]

[0062] Where: I t is the current value measured at a certain moment in the experiment, mA; I i is the initial current of the experiment, i.e. the stable current value before hydrate formation, mA.

[0063] Comparative Example 1, Comparative Example 2 and Comparative Example 3 are respectively a system without adding an inhibitor, a stearic acid amidopropyl dimethylamine system with a saturated carbon chain carbon number of 17 in the R group, and a behenic acid amidopropyl dimethylamine system with a saturated carbon chain carbon number of 21 in the R group. Examples 1 to 11 are single fatty acid amidopropyl dimethylamine systems in the present invention. Examples 12 to 16 are comparisons of the composite system of fatty acid amidopropyl dimethylamine and nano-silicon dioxide in the present invention with a single fatty acid amidopropyl dimethylamine system.

[0064] Comparative Example 1

[0065] 70 ml of No. 5 white oil and 30 ml of deionized water were prepared into an oil-water solution (water content 30%) and added to the swing kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8 MPa and an experimental temperature of 2.5 ° C (no inhibitor was added to the blank group). After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 6.58%, the final slider displacement was 0, and the inhibition level was C.

[0066] Comparative Example 2

[0067] 80ml of No. 5 white oil and 20ml of deionized water were prepared into an oil-water solution (water content 20%), and then 2wt% of stearic acid amide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5℃. After 12h, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 6.44%, the final slider displacement was 0, and the inhibition grade was C.

[0068] Comparative Example 3

[0069] 80ml of No. 5 white oil and 20ml of deionized water were prepared into an oil-water solution (water content 20%), and then 2wt% of behenamide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5℃. After 12h, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 6.73%, the final slider displacement was 0, and the inhibition grade was C.

[0070] Example 1

[0071] 80ml of No. 5 white oil and 20ml of deionized water were prepared into an oil-water solution (water content 20%), and then 2wt% of caprylic acid amide propyl dimethylamine was added and added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5°C. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 21.39%, the final motion range of the slider was 10mm-200mm, the final slider displacement was 190mm, and the inhibition grade was A.

[0072] Example 2

[0073] 70ml of No. 5 white oil and 30ml of deionized water were prepared into an oil-water solution (water content 30%), and then 2wt% of caprylic acid amidopropyl dimethylamine was added and added into a swing kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5°C. After 12h, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 23.9%, the final motion range of the slider was 10mm-200mm, the final slider displacement was 190mm, and the inhibitor grade was A.

[0074] Example 3

[0075] 70ml of No. 5 white oil and 30ml of deionized water were prepared into an oil-water solution (water content 30%), and then 2wt% of lauryl amide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5°C. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 24.28%, the final motion range of the slider was 10mm-200mm, the final slider displacement was 190mm, and the inhibitor grade was A.

[0076] Example 4

[0077] 70ml of No. 5 white oil and 30ml of deionized water were prepared into an oil-water solution (water content 30%), and then 2wt% of oleic acid amide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5°C. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 23.65%, the final motion range of the slider was 10mm-200mm, the final slider displacement was 190mm, and the inhibitor grade was A.

[0078] Example 5

[0079] 70 ml of No. 5 white oil and 30 ml of deionized water were prepared into an oil-water solution (water content 30%), and then 2 wt% of erucic acid amide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8 MPa and an experimental temperature of 2.5 ° C. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 22.46%, the final motion range of the slider was 10 mm-200 mm, the final slider displacement was 190 mm, and the inhibitor grade was A.

[0080] Example 6

[0081] 80ml of No. 5 white oil and 20ml of deionized water were prepared into an oil-water solution (water content 20%), and then 2wt% of lauryl amide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5°C. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 23.25%, the final motion range of the slider was 10mm-200mm, the final slider displacement was 190mm, and the inhibitor grade was A.

[0082] Example 7

[0083] 40ml of No. 5 white oil and 60ml of deionized water were prepared into an oil-water solution (water content 60%), and then 2wt% of lauryl amide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5°C. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 22.48%, the final motion range of the slider was 10mm-200mm, the final slider displacement was 190mm, and the inhibitor grade was A.

[0084] Example 8

[0085] 20ml of No. 5 white oil and 80ml of deionized water were prepared into an oil-water solution (water content 80%), and then 2wt% of lauryl amide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5°C. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 21.67%, the final motion range of the slider was 10mm-200mm, the final slider displacement was 190mm, and the inhibitor grade was A.

[0086] Example 9

[0087] 70ml of No. 5 white oil and 30ml of deionized water were prepared into an oil-water solution (water content 30%), and then 1.5wt% of lauryl amide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5°C. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 23.61%, the final motion range of the slider was 10mm-200mm, the final slider displacement was 190mm, and the inhibitor grade was A.

[0088] Example 10

[0089] 70ml of No. 5 white oil and 30ml of deionized water were prepared into an oil-water solution (water content 30%), and then 1wt% of lauryl amide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5°C. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 22.35%, the final motion range of the slider was 10mm-200mm, the final slider displacement was 190mm, and the inhibitor grade was A.

[0090] Embodiment 11

[0091] 70ml of No. 5 white oil and 30ml of deionized water were prepared into an oil-water solution (water content 30%), and then 0.5wt% of lauramide propyl dimethylamine was added to the shaking kettle. The experimental gas was pure methane, and the performance of the inhibitor was tested under the conditions of an initial pressure of 8MPa and an experimental temperature of 2.5°C. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fraction was 21.26%, the final motion range of the slider was 10mm-200mm, the final slider displacement was 190mm, and the inhibitor grade was A.

[0092] Example 12

[0093] Two experiments were conducted using a swing kettle. 70 ml of No. 5 white oil and 30 ml of deionized water were prepared into an oil-water solution (water content 30%). Only 2 wt% lauramide propyl dimethylamine was added in the first experiment, and 2 wt% lauramide propyl dimethylamine and 0.4 wt% hydrophilic nano-SiO2 were added in the second experiment. The experimental gas was pure methane. Under the conditions of an initial pressure of 8 MPa and an experimental temperature of 2.5 ° C, the performance of the inhibitor was tested. After 12 hours, the temperature and pressure did not change, and hydrates were completely generated. The final hydrate volume fractions were 24.64% and 22.42%, respectively. The final motion range of the slider was 10 mm-200 mm, the final slider displacement was 190 mm, and the inhibitor grade was A. It was found through the displacement speed of the slider that the slider displacement rate was significantly increased after adding 0.4 wt% hydrophilic nano-SiO2.

[0094] Embodiment 13

[0095] Two experiments were conducted using a swing kettle. 70 ml of No. 5 white oil and 30 ml of deionized water were prepared into an oil-water solution (water content 30%). Only 0.5 wt% lauramide propyl dimethylamine was added in the first experiment, and 0.5 wt% lauramide propyl dimethylamine and 0.1 wt% hydrophilic nano-SiO2 were added in the second experiment. The experimental gas was pure methane. Under the conditions of an initial pressure of 8 MPa and an experimental temperature of 2.5 ° C, the performance of the inhibitor was tested. After 12 hours, the temperature and pressure no longer changed, and hydrates were completely generated. The final hydrate volume fractions were 23.64% and 23.26%, respectively. The final motion range of the slider was 10 mm-200 mm, the final slider displacement was 190 mm, and the inhibitor grade was A. By comparing the displacement rate of the slider, it was found that the slider displacement rate was significantly increased after adding 0.1 wt% hydrophilic nano-SiO2.

[0096] Embodiment 14

[0097] Adopt stirring kettle to carry out two experiments, 180ml of No. 5 white oil and 420ml of deionized water are mixed with oil-water solution (water content 30%), only single 0.5wt% cocamidopropyl dimethylamine is added for the first time, and 0.5wt% cocamidopropyl dimethylamine and 0.1wt% hydrophobic nano-SiO2 are added for the second time. The experimental gas is pure methane, and the initial pressure is 9MPa, and the experimental temperature is under the condition of 2.0 ℃, and the performance of the polymerization inhibitor is tested, and hydrate is completely generated, and the final hydrate volume fraction is respectively 32.05% and 32.06%, and it is relatively found by comparison that the relative current significantly reduces after adding 0.1wt% hydrophobic nano-SiO2.

[0098] Embodiment 15

[0099] Adopt stirring kettle to carry out two experiments, 180ml of No. 5 white oil and 420ml of deionized water are mixed with oil-water solution (water content 30%), only single 0.5wt% cocamidopropyl dimethylamine is added for the first time, and 0.5wt% cocamidopropyl dimethylamine and 0.25wt% hydrophobic nano-SiO2 are added for the second time. The experimental gas is pure methane, and the initial pressure is 9MPa, and the experimental temperature is under the condition of 2.0 ℃, and the performance of the polymerization inhibitor is tested, and hydrate is fully generated, and the final hydrate volume fraction is respectively 32.05% and 32.06%, and it is relatively found by contrast that the relative current significantly reduces after adding 0.25wt% hydrophobic nano-SiO2.

[0100] Example 16

[0101] Adopt stirring kettle to carry out two experiments, 180ml of No. 5 white oil and 420ml of deionized water are mixed with oil-water solution (water content 30%), only single 0.5wt% cocamidopropyl dimethylamine is added for the first time, and 0.5wt% cocamidopropyl dimethylamine and 0.5wt% hydrophobic nano-SiO2 are added for the second time. The experimental gas is pure methane, and the initial pressure is 9MPa, and the experimental temperature is under the condition of 2.0 ℃, and the performance of the polymerization inhibitor is tested, and hydrate is fully generated, and the final hydrate volume fraction is respectively 32.05% and 32.11%. By contrast, it is relatively found that the relative current significantly decreases after adding 0.5wt% hydrophobic nano-SiO2.

[0102] Figure 1 This is a standard diagram for classifying the polymerization inhibition levels of the present invention in a swing kettle. If the polymerization inhibitor has strong performance, the hydrate is dispersed in the liquid phase after formation, and the slider can slide freely within the range of 10mm-200mm, the performance of this type of polymerization inhibitor is recorded as Class A. Figure 1 (c); if the inhibitor is weak, hydrate aggregates will precipitate during the whole experiment, resulting in a reduction in the range of motion of the slider but no clogging. The performance of this type of inhibitor is recorded as Class B. Figure 1 (b); If the performance of the hydrate inhibitor is poor, the deposited and aged hydrate will directly block the slider, causing the slider to be stuck and not move, and the performance of the inhibitor is Class C.

[0103] Figure 2 The pressure, temperature, hydrate volume fraction and slider position of the comparative example 1 of the present invention in the swing kettle are changed with time. Figure 2 It can be seen that without adding any inhibitor, hydrate blockage will form at a low hydrate volume fraction of 6%. 6 hours after the start of the experiment, the position of the slider remains unchanged and the displacement is 0 due to hydrate blockage.

[0104] Figure 3 is a graph showing the changes in the hydrate volume fraction and the position of the slider in Comparative Example 2 of the present invention over time. Figure 3 It can be seen that when 2 wt % stearylamidopropyl dimethylamine is added, hydrate blockage will form at a low hydrate volume fraction of 9%. 6.4 h after the start of the experiment, due to hydrate blockage, the slider position remains unchanged and the displacement is 0, proving that the performance of the hydrate inhibitor is poor, the inhibition performance is Class C, and it is unable to prevent the formation of hydrates.

[0105] Figure 4 is a graph showing the changes in pressure, temperature, hydrate volume fraction and slider position over time in Example 3 of the present invention in a swing kettle. Figure 4It can be seen that compared with the non-additive system in comparative example 2 and the ineffective inhibitor system in comparative example 3, when 2 wt% lauryl amide propyl dimethylamine was added, the slider could slide freely in the range of 10 mm-200 mm during the whole experiment, and the displacement was 190 mm. This proves that the inhibitor has excellent performance, the inhibition performance is A-level, and the aggregation of hydrates can be prevented at the final hydrate volume fraction of 24.28%.

[0106] Figure 5 The hydrate volume fraction and slider position of Example 13 of the present invention in the swing kettle after adding 0.5wt% lauramide propyl dimethylamine and 0.1wt% hydrophilic nano-SiO2 change with time. Figure 5 It can be seen that compared with the non-additive system in comparative example 2 and the ineffective inhibitor system in comparative example 3, when 0.5wt% lauramide propyl dimethylamine and 0.1wt% hydrophilic nano-SiO2 were added, the slider could slide freely in the range of 10mm-200mm during the whole experiment, and the displacement was 190mm. It proves that the performance of the inhibitor is excellent, the inhibitor performance is A-level, and the aggregation of hydrates can be prevented at the final hydrate volume fraction of 23.26%.

[0107] Figure 6 This is a graph of the displacement speed of the slider in Example 13 of the present invention in a swing kettle as a function of the hydrate volume fraction. In both sets of experiments, the slider can slide freely in the range of 10mm-200mm, with a displacement of 190mm, proving that the performance of the inhibitor is excellent, and the inhibitory performance is both Class A, which can prevent the aggregation of hydrates at the final hydrate volume fractions of 23.64% and 23.26%, respectively. For inhibitors with superior performance, although hydrates can be dispersed in the liquid phase after generation, and the slider can slide freely in the range of 10mm-200mm, the hydrate particles will increase the viscosity of the fluid and reduce the displacement rate of the slider. The viscosity of the hydrate slurry and the resistance encountered by the slider during movement can be obtained by monitoring the movement rate of the slider, thereby evaluating the performance of the hydrate inhibitor. The greater the movement rate of the slider, the smaller the viscosity of the hydrate slurry, and the smaller the resistance encountered by the slider, proving that the performance of the hydrate inhibitor is stronger. By Figure 6 It can be seen that compared with the single 0.5wt% lauramide propyl dimethylamine system, the displacement rate of the slider is significantly reduced after adding 0.1wt% hydrophilic nano-SiO2, which proves that the performance of 0.5wt% lauramide propyl dimethylamine + 0.1wt% hydrophilic nano-SiO2 is more superior and can reduce the viscosity of the slurry in the hydrate dispersion system.

[0108] Figure 7This is a graph of the relative current of Example 14 of the present invention in the stirring kettle as it changes with the hydrate volume fraction. During the experiment, the formation and aggregation of hydrates will increase the viscosity of the liquid phase. The greater the degree of hydrate aggregation, the higher the viscosity of the slurry, and the greater the torque borne by the stirring paddle, which is numerically reflected in the current value of the stirring motor. The relative current value can be used to evaluate the performance of the hydrate inhibitor. The stronger the inhibitory performance, the smaller the relative current of the stirring motor. Figure 7 It can be seen that in a single 0.5wt% cocamidopropyl dimethylamine system, as the hydrate volume fraction increases to 30%, the relative current increases to a peak value of 3.75. As the hydrate volume fraction increases to the final 32.05%, some hydrates are broken under the stirring of the stirring paddle, and the relative current decreases to 2.2. After adding 0.5wt% cocamidopropyl dimethylamine + 0.1wt% hydrophobic nano-SiO2, the relative current is significantly reduced compared with the single 0.5wt% cocamidopropyl dimethylamine system. During the entire experimental process, the relative current value is less than 1.4 in the range of hydrate volume fraction 0-32.11%. It is proved that the hydrate inhibitor after adding 0.1wt% hydrophobic nano-SiO2 system has stronger inhibition performance, the viscosity of the hydrate slurry is smaller, and the torque of the stirring paddle is smaller.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A fatty acid amide propyl dimethylamine hydrate inhibitor, It is characterized in that It comprises fatty acid amide propyl dimethylamine, wherein the fatty acid amide propyl dimethylamine has a structural formula as shown in Formula I, wherein R in Formula I is a saturated hydrocarbon group having 1 to 18 carbon atoms or an unsaturated hydrocarbon group having 1 to 22 carbon atoms, ； (Formula I) The invention also includes nanoparticles, wherein the polymerization inhibitor is mainly composed of fatty acid amide propyl dimethylamine and nanoparticles; the nanoparticles are hydrophobic nano-SiO with a particle size of 20 nm. 2 Particles.

2. A fatty acid amide propyl dimethylamine hydrate inhibitor according to claim 1, It is characterized in that The fatty acid amide propyl dimethylamine is selected from any one of the following; The fatty acid amide propyl dimethylamine is caprylic acid amide propyl dimethylamine, and the molecular formula is C 13 H 28 N 2 O; The fatty acid amide propyl dimethylamine is lauramide propyl dimethylamine, and the molecular formula is C 17 H 36 N 2 O, the structural formula is shown in Formula IV, ； (Formula IV) The fatty acid amide propyl dimethylamine is oleic acid amide propyl dimethylamine, and the molecular formula is C 23 H 46 N 2 O, the structural formula is shown in formula V, ； (Formula V) The fatty acid amide propyl dimethylamine is linoleic acid amide propyl dimethylamine, and the molecular formula is C 23 H 44 N 2 O, the structure is as shown in formula VI, ； (Formula VI) The fatty acid amide propyl dimethylamine is erucic acid amide propyl dimethylamine, and the molecular formula is C 27 H 54 N 2 O, the structural formula is shown in formula VIII, 。 (Formula VIII) 3. A fatty acid amide propyl dimethylamine hydrate inhibitor according to claim 2, It is characterized in that The mass fraction of the fatty acid amide propyl dimethylamine is 0.5 wt % to 2 wt %.

4. A fatty acid amide propyl dimethylamine hydrate inhibitor according to claim 1, It is characterized in that The mass fraction of the fatty acid amide propyl dimethylamine is 0.5 wt % to 2 wt %, and the mass fraction of the nanoparticles is 0.1 wt % to 0.5 wt %.

5. Use of the fatty acid amide propyl dimethylamine hydrate inhibitor according to any one of claims 1 to 3 in the prevention and treatment of gas hydrates in deepwater oil and gas gathering and transportation pipelines.

6. Use of the fatty acid amide propyl dimethylamine hydrate inhibitor according to claim 5 in the prevention and treatment of gas hydrates in deepwater oil and gas gathering and transportation pipelines, It is characterized in that It is applicable to the oil, gas and water three-phase coexistence system, and the applicable water content range is 20-80%.

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