A nanometer drive material and its preparation method and application

Abstract

The present application discloses a method for preparing a nano-scale flooding material, comprising the following steps: S1, reacting raw material I containing an acrylate compound, a styrene compound, a crosslinker, an emulsifier, an alcohol dispersant, and an oil-soluble initiator to obtain an oil-soluble material; S2, reacting raw material II containing the oil-soluble material obtained in step S1, a water-soluble monomer, a crosslinker, and an initiator II to obtain the nano-scale flooding material. The nano-scale flooding material prepared by the preparation method of the present application has a particle size that can be adjusted to 300 to 500 nm and has a controlled release characteristic. During migration to the deep reservoir, it releases an oil-soluble core material, which blocks water when it encounters water and washes oil when it encounters oil, thereby achieving a deep flooding effect.

Description

Technical Field

[0001] The present application relates to a nanometer flooding material and a preparation method and application thereof, belonging to the field of low permeability flooding. Background Art

[0002] my country's oil demand continues to grow, and its dependence on foreign oil continues to rise. In 2019, China's crude oil dependence reached 72%, exceeding the international warning line by 22 percentage points, making it the world's largest crude oil importer. Maintaining a stable domestic crude oil production of 200 million tons is a red line for national energy security and cannot be compromised.

[0003] After long periods of waterflooding, oilfields often face significant water content, leading to a decrease in daily oil production and a sharp drop in crude oil production. This same problem also applies to low-permeability oilfields. The market urgently needs efficient, intelligent flooding materials to control water and increase oil production. Furthermore, in actual field applications, such as in the Changqing Oilfield, low porosity and permeability are prominent, but they also exhibit strong heterogeneity due to the presence of well-developed natural and structural fractures within the reservoir. These fractured reservoirs require flooding materials with a specific particle size range. Summary of the Invention

[0004] According to one aspect of the present application, a nano-scale flooding material is provided. Nano-core-shell materials are synthesized by a one-step or multi-step polymerization method. With the help of molecular design theory, the molecular structure and molecular weight distribution of the oil-soluble nano-material in the core are regulated to design a core material of a certain size. A water-soluble monomer is used as the outer shell. This shell has good temperature and salt resistance and protects and supports the core. In the process of the water-soluble shell material carrying the core to the deep reservoir, the water-soluble shell material releases the oil-soluble core material due to factors such as formation shear, adsorption or swelling. Through the migration of the oil-soluble core in the reservoir, it blocks water when encountering water and washes oil when encountering oil, thereby playing the role of intelligent flooding. The particle size can be adjusted to 300nm to 500nm, which meets the particle size range requirements of flooding materials required for fracture-type reservoirs with natural fractures and structural fractures inside the reservoir and complete fracture development.

[0005] This application adopts the following technical solutions:

[0006] A method for preparing a nano-propulsion material, characterized by comprising the following steps:

[0007] S1, reacting raw material I containing an acrylate compound, a styrene compound, a crosslinking agent, an emulsifier, an alcohol dispersant, and an oil-soluble initiator to obtain an oil-soluble material;

[0008] S2. Reacting the raw material II containing the oil-soluble material obtained in step S1, the water-soluble monomer, the crosslinking agent, and the initiator II with II to obtain the nano-propulsion material.

[0009] Optionally, the oil-soluble initiator I is selected from at least one of azobisisobutyronitrile, dialkyl peroxide, diacyl peroxide, tertiary amine, cyclopentane salt, mercaptan, triethylaluminum, triethylboron, and cuprous naphthenate.

[0010] Optionally, the alcohol dispersant is selected from at least one monohydric alcohol selected from ethanol, methanol, and propanol.

[0011] Optionally, the olefinic ester compound is selected from at least one of octadecyl acrylate, octadecyl methacrylate, and methyl methacrylate.

[0012] Optionally, the styrene compound is selected from at least one of styrene, methylstyrene, dimethylstyrene and styrene propene.

[0013] Optionally, the cross-linking agent is selected from at least one of NN methylenebisacrylamide, methylene acrylamide, and NN vinylbisacrylamide.

[0014] Optionally, the emulsifier is selected from at least one of Tween 80, Tween 60 and Tween 20.

[0015] Optionally, the water-soluble monomer is selected from at least one of acrylamide, acrylic acid, sodium acrylate, and 2-acrylamido-2-methylpropanesulfonic acid.

[0016] Optionally, the initiator II is selected from at least one of potassium sulfate, sodium persulfate, and ammonium persulfate.

[0017] Optionally, step S1 includes:

[0018] S11, obtaining a mixture I containing an emulsifier, a cross-linking agent, an alcohol dispersant, an oil-soluble initiator, and water;

[0019] S12, obtaining a mixture II containing an olefinic acid ester compound and a styrene compound;

[0020] S13, adding the mixture II to the mixture I, and performing reaction I to obtain the oily material.

[0021] The use of alcohol dispersants can accelerate the growth rate of latex particles during the emulsification process, thereby increasing the final particle size of the core-shell structured nano-displacement material. The corresponding oil-soluble initiator is more likely to initiate in the alcohol system.

[0022] Optionally, in step S1, the raw material I contains the following components in parts by weight: 12 to 18 parts of acrylate compounds, 17 to 25 parts of styrene compounds, 0.02 to 0.04 parts of cross-linking agents, 12 to 18 parts of emulsifiers, 16 to 24 parts of alcohol dispersants, and 0.1 to 0.3 parts of oil-soluble initiators.

[0023] Optionally, the raw material I further includes 260 to 300 parts by weight of water.

[0024] Optionally, in step S1, the conditions of reaction I are: deoxygenating raw material I for 20 to 30 minutes, and reacting at 60 to 70° C. for 3 to 6 hours after deoxygenation.

[0025] Optionally, step S2 includes:

[0026] S21, obtaining a mixture III containing a water-soluble monomer, a cross-linking agent, and water;

[0027] S22, mixing the oil-soluble material obtained in step S1 with mixture III to remove oxygen;

[0028] S23, mixing the mixture containing the initiator and water IV, and deoxygenating;

[0029] S24, adding the deoxygenated mixture IV in S23 to the deoxygenated mixture III in S22, and performing reaction II to obtain the nano-propulsion material.

[0030] Optionally, in step S2, the raw material II comprises the following components in parts by weight: 40 to 60 parts of oil-soluble material, 40 to 60 parts of water-soluble monomer, 0.06 to 0.09 parts of cross-linking agent, and 0.04 to 0.05 parts of initiator II.

[0031] Optionally, the raw material II further comprises 80 to 100 parts by weight of water.

[0032] Optionally, in step S2, the conditions of reaction II are: deoxygenation treatment of raw material II for 15 to 60 minutes, and reaction at 70 to 90° C. for 2 to 4 hours after deoxygenation.

[0033] Optionally, the steps S1, S2, S11 to S13, and S21 to S23 independently further include stirring, with a stirring speed of 200 to 550 rpm and a stirring temperature of 50 to 80°C.

[0034] The oil-soluble material obtained in step S1 is the oily core in the core-shell structure of the nano-propulsion material. In step S2, the water-soluble monomer acts as an outer shell and reacts with the oily core material to form a core-shell structure.

[0035] Optionally, the deoxygenation treatment is to pass nitrogen into the reaction raw materials for a ventilation time of 15 to 60 minutes.

[0036] According to another aspect of the present application, a nano-displacement material prepared by the above-mentioned preparation method is provided, wherein the nano-displacement material is a core-shell structure in which a water-soluble material encapsulates an oil-soluble material;

[0037] Optionally, the particle size of the nano-propulsion material is 300-500 nm.

[0038] Optionally, the particle size of the nano-propulsion material is any value among 300 nm, 320 nm, 340 nm, 360 nm, 380 nm, 400 nm, 420 nm, 440 nm, 460 nm, 480 nm, 500 nm, or any range therebetween.

[0039] According to another aspect of the present application, there is provided a nanometer displacement material prepared by the above preparation method, and use of at least one of the above nanometer displacement materials in a displacement agent for low permeability oil fields.

[0040] Optionally, the nano-profile material is adapted to a reservoir permeability of 100 mD to 200 mD.

[0041] Optionally, the nano-displacement material can be controllably released by stirring for 2 to 5 hours at 80° C. and a salinity of 10 W, and the particle size can be changed to 0.25 to 3 μm after release.

[0042] The beneficial effects of this application include:

[0043] The nano-scale flooding material preparation method provided in this application uses ethanol as the dispersion system to increase particle size. At the same time, the oil-soluble initiator azobisisobutyronitrile (AIBN) is used as the initiator. The synthesis method can control the particle size to 300nm-500nm, and the material's application range can be increased to a permeability of 100mD-200mD. The nano-scale flooding material provided in this application has a core-shell structure in which a water-soluble material encapsulates an oil-soluble material. This shell has excellent temperature and salt resistance, providing protection and support for the core. The water-soluble shell material carries the core to the deep reservoir and then releases the oil-soluble core material, blocking water when encountering water and washing oil when encountering oil, thereby achieving intelligent flooding and possessing controlled release characteristics. At 80°C, the particle size can directly increase to the micron level after stirring for 3 hours under 5W salinity, with a large amount of precipitation. At 10W salinity, the particle size can directly increase to the micron level after stirring for 2 hours, and the particle size can increase to 3μm. The nanometer flooding material provided in the present application was used in a flooding agent, and the plugging rate was tested to be 65.78% and the EOR was 22%. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a particle size diagram of the nano-propulsion material in Example 1 of the present application.

[0045] Figure 2 This is the infrared test spectrum of the nano-tuning material of Example 1 of the present application.

[0046] Figure 3 This is a comparison chart of the particle sizes of the nano-propulsion material of Example 1 of the present application at different stirring times at 80°C.

[0047] Figure 4 This is a graph showing the particle size of the nano-displacement material of Example 1 of the present application after complete release at 80°C.

[0048] Figure 5 This is a diagram showing the plugging properties of the nano-displacement material of Example 1 of the present application when used as a displacement agent. DETAILED DESCRIPTION

[0049] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0050] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0051] Unless otherwise specified, conventional methods were used for testing, and instrument settings were those recommended by the manufacturer.

[0052] Example 1 Preparation of Nano-Adjustable Displacement Material

[0053] (1) Weigh 280 g of deionized water, 20 g of anhydrous ethanol, and 15 g of Tween 80, and heat with magnetic stirring at 500 rpm and 55°C until the Tween 80 is dissolved. Then, add 0.03 g of NN methylenebisacrylamide and 0.21 g of a soluble initiator (azobisisobutyronitrile).

[0054] (2) Weigh 9 g of octadecyl acrylate, 21 g of styrene, and 6 g of methyl methacrylate, and heat to dissolve them at 55°C with magnetic stirring at 500 rpm;

[0055] (3) Dissolve (2) and pour into (1) at once, stir magnetically at 55°C and 500 rpm for 30 min, and after a stable emulsion is formed, flow N2 for 20 min;

[0056] (4) After the ventilation is completed, the flask is assembled and stirred at a speed of 200 rpm (mechanical). The oil bath is set to 70°C and the temperature is raised. The reaction is completed after 3 hours.

[0057] (5) Weigh 36 g of acrylamide monomer and 18 g of AMPS-Na monomer, add 86 g of deionized water to dissolve, and then add 0.075 g of N-N-methylenebisacrylamide;

[0058] (6) After the core solution has finished reacting and cooled, mix it with the shell solution dissolved in (5), stir mechanically at 200 rpm at room temperature for 30 min, and pass N2 for 30 min;

[0059] (7) Weigh 0.45 g of potassium persulfate, add 10 g of deionized water, shake to dissolve, and then pass N2 for 15 min;

[0060] (VIII) After the ventilation is completed, the flask is assembled, the oil bath is set to 80°C and the speed is 200 rpm (mechanical), potassium persulfate is added after 10 minutes, and the reaction is completed after 3 hours after the initiator is added to obtain a core-shell structure nano-scale displacement material in which a water-soluble material encapsulates an oil-soluble material, which is recorded as CSN-03. The particle size distribution diagram is shown in the attached figure. Figure 1 As shown, the particle size can be adjusted to 300nm~500nm by attaching Figure 2 It can be seen that the infrared spectra of the core material and the core-shell material are shown in the figure. -1 、2850cm -1 The two absorption peaks at 1601cm are the stretching vibration absorption peaks of the CH bond in the -CH2- on the main chain; -1 、1493cm -1 、1452cm -1 The three absorption peaks on the left are the rigid vibration peaks of the CC bond on the main chain skeleton; 757cm -1 、698cm -1 The two strong absorption peaks at 3340 cm-1 are the bending vibration peaks of the CH bond on the side chain benzene ring. Compared with the core, the infrared spectrum curve of the core-shell material is -1 、3160cm -1 The stretching vibration absorption peak of NH bond appears at 1650cm -1 The stretching vibration absorption peak of C=O bond appears at 1050~1200cm -1 The stretching vibration absorption peak of the S=O bond appears at , which verifies that the nano-tuning material is successfully synthesized.

[0061] Comparative Example 1

[0062] The preparation method is the same as that of Example 1, except that in step (1), the oil-soluble initiator azobisisobutyronitrile (AIBN) is replaced with potassium persulfate, and the particle size of the prepared nano-propagation material is 80 nm to 100 nm.

[0063] Comparative Example 2

[0064] The preparation method is the same as that of Example 1, except that in step (1), the oil-soluble initiator azobisisobutyronitrile (AIBN) is replaced with potassium persulfate, and anhydrous ethanol is not used. The particle size of the prepared nano-propagation material is 100 nm to 120 nm.

[0065] Test Example 1 Controlled Release Performance: Particle Sizes at Different Stirring Times

[0066] As attached Figure 3As shown in the figure, at 80°C, the particle size of the CSN-03 material did not change much within 5 hours of stirring at a salinity of 1W, and it failed to be released; at 5W salinity, the particle size did not change much within 4 hours of stirring, and it failed to be released. After 5 hours, it began to show an obvious upward trend and precipitation appeared; at 10W salinity, the particle size did not change much within 2 hours of stirring, and it failed to be released. After 3 hours, the particle size directly increased to the micron level and a large amount of precipitation appeared. Therefore, at 80°C, the CSN-03 material failed to be released within 5 hours of stirring at a salinity of 1W, began to release after 4 hours of stirring at a salinity of 5W, and began to release after 3 hours of stirring at a salinity of 10W, and the particle size eventually increased to about 3um (as shown in the attached figure). Figure 4 shown).

[0067] Test Example 2: Plugging Performance Test

[0068] The displacement material CSN-03 in Example 1 was used to prepare a displacement agent 1PV with a content of 0.1% for testing.

[0069] The plugging performance test method is as follows:

[0070] (1) Take the dried core and weigh its dry weight. After vacuum saturation with simulated water, weigh its wet weight and calculate the pore volume.

[0071] (2) Water permeability: Inject water at a rate of 0.2 mL / min. After the injection pressure stabilizes, calculate the water permeability of the core;

[0072] (3) Oil saturation: Inject oil at a rate of 0.2 mL / min until the produced fluid contains no water. Record the produced water volume and calculate the oil saturation.

[0073] (5) Agent flooding: Inject the prepared displacement agent 1PV at a rate of 0.2 mL / min, record the liquid production, water production, oil production and pressure at regular intervals, and age for 12 hours.

[0074] (6) Subsequent oil flooding: Water flooding was performed at a rate of 0.2 mL / min, and the pressure changes were recorded at regular intervals until the pressure remained stable for 2 h.

[0075] Experimental conditions include:

[0076] 1) Experimental water: 100,000 ml of mineralized water;

[0077] The composition and preparation method of simulated water (10wNaCl+5000CaCl2·2H20) are as follows:

[0078] Table 1 Formulation of simulated water

[0079]

[0080] 2) Experimental oil: Chang 6 crude oil: kerosene = 1:4;

[0081] 3) Experimental core: Long 6 core, specific parameters are shown in Table 2.

[0082] Table 2 Core parameters

[0083] (4) Injection system: 1000ppm CSN-03

[0084] Table 3 Performance evaluation results of profile control and displacement agents

[0085] System Name Interfacial tension, mN / m Particle size, nm pH Viscosity, cp CSN-03 / 300 7 3.2

[0086] (5) Experimental temperature: 60℃.

[0087] The results are as attached Figure 5 As shown, the plugging rate is 65.78% and the EOR is 22%.

[0088] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a nano-profile material, characterized in that: The steps include: S1, reacting raw material I containing an acrylate compound, a styrene compound, a crosslinking agent, an emulsifier, an alcohol dispersant, and an oil-soluble initiator to obtain an oil-soluble material; S2, reacting the raw material II containing the oil-soluble material obtained in step S1, the water-soluble monomer, the crosslinking agent, and the initiator II with II to obtain the nano-propulsion material; The alcohol dispersant is selected from at least one monohydric alcohol selected from ethanol, methanol, and propanol; The particle size of the nano-propulsion material is 300-500 nm.

2. The preparation method according to claim 1, characterized in that The oil-soluble initiator I is selected from at least one of azobisisobutyronitrile, dialkyl peroxide, diacyl peroxide, tertiary amine, cyclopentane salt, mercaptan, triethylaluminum, triethylboron, and cuprous naphthate; The olefin ester compound is selected from at least one of octadecyl acrylate, octadecyl methacrylate, and methyl methacrylate; The styrene compound is selected from at least one of styrene, methylstyrene, dimethylstyrene and styrene propene; The cross-linking agent is selected from at least one of NN methylene bisacrylamide, methylene acrylamide, and NN vinyl bisacrylamide; The emulsifier is selected from at least one of Tween 80, Tween 60, and Tween 20; The water-soluble monomer is selected from at least one of acrylamide, acrylic acid, sodium acrylate, and 2-acrylamido-2-methylpropanesulfonic acid; The initiator II is selected from at least one of potassium sulfate, sodium persulfate, and ammonium persulfate.

3. The preparation method according to claim 1, characterized in that The step S1 comprises: S11, obtaining a mixture I containing an emulsifier, a cross-linking agent, an alcohol dispersant, an oil-soluble initiator, and water; S12, obtaining a mixture II containing an olefinic acid ester compound and a styrene compound; S13, adding the mixture II to the mixture I, and performing reaction I to obtain the oily material.

4. The preparation method according to claim 1, characterized in that In step S1, the raw material I contains the following components in parts by weight: 12 to 18 parts of acrylate compounds, 17 to 25 parts of styrene compounds, 0.02 to 0.04 parts of cross-linking agents, 12 to 18 parts of emulsifiers, 16 to 24 parts of alcohol dispersants, and 0.1 to 0.3 parts of oil-soluble initiators.

5. The preparation method according to claim 1 or 3, characterized in that In step S1, the conditions of reaction I are: deoxygenation treatment of raw material I for 20 to 30 minutes, and reaction at 60 to 70° C. for 3 to 6 hours after deoxygenation.

6. The preparation method according to claim 1, characterized in that In step S2, the raw material II comprises the following components in parts by weight: 40 to 60 parts of oil-soluble material, 40 to 60 parts of water-soluble monomer, 0.06 to 0.09 parts of cross-linking agent, and 0.04 to 0.05 parts of initiator II.

7. The preparation method according to claim 1, characterized in that In step S2, the conditions of reaction II are as follows: raw material II is deoxygenated for 15 to 60 minutes, and then reacted at 70 to 90° C. for 2 to 4 hours.

8. A nano-propulsion material prepared according to the preparation method according to any one of claims 1 to 7, characterized in that: The nanometer displacement material is a core-shell structure in which a water-soluble material encapsulates an oil-soluble material.

9. Use of at least one of the nano-displacement material prepared by the preparation method according to any one of claims 1 to 7 and the nano-displacement material according to claim 8 in a displacement agent for low permeability oil fields.

10. The use according to claim 9, characterized in that The nanometer displacement material is suitable for oil reservoir permeability of 100mD to 200mD.

11. The use according to claim 9, characterized in that The nanometer drive material can be controllably released by stirring for 2 to 5 hours at 80° C. and a salinity of 10W, and the particle size can be changed to 0.25 to 3 μm after release.

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