Hydrophobic association polymer and preparation method thereof, gel and preparation method thereof

Abstract

The invention discloses a preparation method of a hydrophobic associated polymer, which comprises the following steps: in an inert atmosphere, mixing an acrylamide monomer, a betaine monomer, a salt-tolerant monomer and a cationic hydrophobic monomer, adjusting the pH value to be alkaline, heating, adding an azo initiator, and reacting to obtain the hydrophobic associated polymer. The invention provides temperature-resistant and salt-resistant double-network gel and a preparation method thereof, and aims to solve the problems that most existing gel plugging agent systems are of single-layer three-dimensional network structures, have the defects of low resistance to high salt and dilution, low strength and the like, and are difficult to meet the requirements of high-temperature and high-salt oil reservoirs.

Description

Technical Field

[0001] The invention relates to the technical field of jelly, and in particular to a hydrophobic associating polymer and a preparation method thereof, a jelly and a preparation method thereof. Background Art

[0002] In the later stage of water injection reservoir development, high water production is an unavoidable problem, which has a great impact on the economic benefits of oil and gas production. As water injection development continues, the water content of the oil wells rises rapidly, and the water index rises sharply, resulting in explosive flooding of the oil wells, affecting the final recovery rate.

[0003] The oil reservoirs in the Tahe Oilfield are characterized by high temperature, high mineralization, high water content and strong heterogeneity. At present, cement plugging agents, polymer gels, pre-crosslinked gel particles, and gels are commonly used for profile control and water plugging. Among them, gels are widely used because of their low cost, adjustable gelling time and strength, and can be used for plugging at different depths. However, the application of gels in reservoirs with harsh conditions such as high temperature and high salinity still faces technical difficulties. Therefore, it is urgent to develop a strong gel-type profile control and water plugging agent that can solve the problem of high water content in high-temperature and high-salinity reservoirs. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a temperature-resistant and salt-resistant double-network jelly and a preparation method thereof, so as to solve the problem that most existing jelly plugging agent systems are single-layer three-dimensional network structures, have the disadvantages of being intolerant to high salt, intolerant to dilution, and having low strength, and are difficult to meet the requirements of high-temperature and high-salt oil reservoirs.

[0005] The technical solution adopted by the present invention to solve the technical problem is:

[0006] A method for preparing a hydrophobically associating polymer comprises the following steps:

[0007] In an inert atmosphere, acrylamide monomer, betaine monomer, salt-tolerant monomer and cationic hydrophobic monomer are mixed, the pH is adjusted to alkaline, an azo initiator is added after heating, and the hydrophobic associating polymer is prepared after reaction.

[0008] Preferably, the molar ratio of the acrylamide monomer, the betaine monomer, the salt-tolerant monomer and the cationic hydrophobic monomer is 1:(0.1-0.3):(0.02-0.08):(0.01-0.03).

[0009] Preferably, the betaine monomer is 2-((3-methacrylamidopropyl)dimethylamine)acetate.

[0010] Preferably, the salt-tolerant monomer is one or more of methacryloyloxyethyl trimethyl ammonium chloride, dimethyldiallyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride, allyl trimethyl ammonium chloride, methacrylamide ethyl trimethyl ammonium chloride, and methacryloyloxyethyl dimethyl benzyl ammonium chloride.

[0011] Preferably, the cationic hydrophobic monomer is one or more of N,N-dimethyl(dodecyl-docosyl)allyl ammonium chloride, N-(dodecyl-docosyl)acrylamide, and bis(dodecyl-docosyl)methyl allyl ammonium chloride.

[0012] Preferably, the azo initiator is water-soluble azo V-044, water-soluble azo V50, or water-soluble azo V061.

[0013] Preferably, adjust the pH to 7-9.

[0014] The present invention also provides a hydrophobically associating polymer, which is a hydrophobically associating polymer prepared by the preparation method described above.

[0015] The present invention also provides a preparation method of a gel, which includes the following:

[0016] Stir and mix the polymer mother liquor and the mixed crosslinking agent solution until crosslinked;

[0017] Among them, the polymer mother liquor includes 0.5 wt% - 2.5 wt% of the hydrophobically associating polymer and 0.2 wt% - 1 wt% of the AM / AMPS copolymer, and the rest is water. The hydrophobically associating polymer is the hydrophobically associating polymer described in claim 8. AM is acrylamide, AMPS is 2-acrylamido-2-methylpropanesulfonic acid, and the AM / AMPS copolymer is a copolymer of the two. The mixed crosslinking agent solution includes: 0.4 wt% - 2 wt% of the phenolic aldehyde crosslinking agent solution and 0.025 wt% - 0.125 wt% of the organic chromium crosslinking agent solution.

[0018] The present invention also provides a gel, which is a gel prepared by the preparation method described above.

[0019] The technical effects achieved:

[0020] The provided hydrophobically associating polymer is used to prepare a gel plugging agent based on an AM / AMPS copolymer and introduce crosslinking to it, achieving an optimized upgrade of the grid structure. The two form an interpenetrating double-network structure, preparing a novel hydrophobically associating double-network gel system with high temperature resistance, high salt resistance, and dilution resistance. This double-network structured gel shows great application potential in profile control and water plugging. The gel system with a double-network structure using this hydrophobically associating polymer has stronger toughness, that is, the gel with a double-network structure has greater strength. There are some protruding salt crystals attached to the surface of the network structure. This is because the groups on the hydrophobically associating polymer chain respectively change the original free water into bound water through complexation with salts and solvent action of water, making its microstructure more reliable and enhancing the salt resistance of the colloid. This structure makes the gel with a double-network structure have better thermal salt stability than the gel with a general single-network structure. The gel prepared with it can form a gel in only 3 hours, and the gel strength is grade H, the maximum yield stress is 326.42 Pa, the breakthrough pressure is 88.19 MPa / m, and the dehydration rate in 30 days is 1.14%. It has higher strength, salt resistance, temperature resistance, and dilution resistance than the gel with a single-layer network structure. Brief Description of the Drawings

[0021] Figure 1 Schematic diagram of the yield stress of the single-network gel in the comparative example;

[0022] Figure 2 Schematic diagram of the yield stress of the double-network gel in Example 5. Detailed Description of the Invention

[0023] The following will further describe the present invention in detail.

[0024] The present invention will be described in more detail below with reference to the drawings, in which preferred embodiments of the present invention are shown. It should be understood that those skilled in the art can modify the present invention described herein and still achieve the beneficial effects of the present invention. Therefore, the following description should be understood as a broad guidance for those skilled in the art and not as a limitation to the present invention.

[0025] For clarity, not all features of the actual embodiments are described. In the following description, well-known functions and structures are not described in detail because they would clutter the present invention with unnecessary details. It should be considered that in the development of any actual embodiment, a large number of implementation details must be made to achieve the specific goals of the developer.

[0026] To make the purpose and features of the present invention more obvious and understandable, the specific embodiments of the present invention will be further described below with reference to the drawings. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, only for the purpose of conveniently and clearly assisting in explaining the embodiments of the present invention.

[0027] The gel system with a double-network structure in this application has stronger toughness, that is, the gel with a double-network structure has greater strength. Some convex salt crystals adhere to the surface of the network structure. This is because the groups on the hydrophobic associating polymer chains change the original free water into bound water through complexation with salts and solvent action with water respectively, making its microstructure more reliable and enhancing the salt resistance of the colloid. This structure enables the gel with a double-network structure to have better thermal salt stability than the gel with a general single-network structure. Therefore, it can be seen that the gel with a double-network structure shows great application potential in profile control and water plugging.

[0028] The double-network gel in this application can form a gel in only 3 hours, and the gel strength is grade H, the maximum yield stress is 326.42 Pa, the breakthrough pressure is 88.19 MPa / m, and the dehydration rate in 30 days is 1.14%. It has higher strength, salt tolerance, temperature resistance, and dilution resistance than the gel with a single-layer network structure. This research fills the technical gap of high-temperature and salt-resistant high-strength water plugging gel in Tahe Oilfield and has good practical application prospects.

[0029] The betaine monomer in the betaine monomer structural unit is 2-((3-methacrylamidopropyl)dimethylamine) acetate, and its chemical formula is as follows:

[0030]

[0031] Among them, the preparation of the betaine monomer includes:

[0032] After dissolving N-(3-dimethylaminopropyl)methacrylamide in water and heating it to 25°C - 65°C, a sodium chloroacetate solution with a pH value of 7 - 8 is dropped in, and the reaction is carried out for 4 h - 8 h; among them, the molar ratio of N-(3-dimethylaminopropyl)methacrylamide to sodium chloroacetate is 1:(0.5 - 2).

[0033] The synthesis route of the betaine monomer is as follows:

[0034]

[0035] The betaine monomer is used as a structure-enhancing monomer in the hydrophobic associating polymer structure, and the network structure stability and compactness are enhanced through chelation with metal ions, further strengthening the temperature and salt resistance of the network structure.

[0036] Example 1:

[0037] This example provides a high-temperature and salt-resistant double-network gel, and the gel solution includes the following components:

[0038] 60 g of polymer mother liquor (including 0.5 wt% of hydrophobically associating polymer, 1.0 wt% of AM / AMPS copolymer and water), 10 g of mixed crosslinking agent solution (including 0.025 wt% of organic chromium crosslinking agent, 2.0 wt% of phenolic aldehyde crosslinking agent).

[0039] The temperature-resistant and salt-resistant double-network gel of this example is prepared by the following method:

[0040] Preparation of hydrophobically associating polymer: Dissolve 1.0 mol of acrylamide, 0.1 mol of betaine monomer, 0.08 mol of salt-resistant monomer DMC and 0.01 mol of cationic hydrophobic monomer C18DMAAC in deionized water, adjust the pH value to 7, purge with nitrogen to remove oxygen and stir for about 30 min, raise the temperature of the polymerization solution to 40 °C, then add V-044 to initiate polymerization, and carry out the polymerization reaction at a constant temperature in a constant-temperature water bath for 3 h, take out, shear, granulate, dry and pulverize to obtain the hydrophobically associating polymer.

[0041] Preparation of polymer mother liquor: Add 0.3 g of hydrophobically associating polymer and 0.6 g of AM / AMPS copolymer to 59.1 g of formation water, stir evenly to fully dissolve the polymer.

[0042] Preparation of mixed crosslinking agent solution: Add 0.0025 g of organic chromium crosslinking agent and 0.2 g of phenolic aldehyde crosslinking agent to 9.7975 g of formation water, stir evenly.

[0043] Preparation of double-network gel: Add 10 g of mixed crosslinking agent to 60 g of polymer mother liquor, stir evenly, react at 120 °C for 2 h to obtain the double-network gel.

[0044] Example 2:

[0045] This example provides a temperature-resistant and salt-resistant double-network gel, and the gel solution includes the following components:

[0046] 60 g of polymer mother liquor (including 0.5 wt% of hydrophobically associating polymer, 0.6 wt% of AM / AMPS copolymer and water), 20 g of mixed crosslinking agent solution (including 0.025 wt% of organic chromium crosslinking agent, 1.2 wt% of phenolic aldehyde crosslinking agent).

[0047] The temperature-resistant and salt-resistant double-network gel of this example is prepared by the following method:

[0048] Preparation of hydrophobically associating polymer: Dissolve 1.0 mol of acrylamide, 0.2 mol of betaine monomer, 0.05 mol of salt-tolerant monomer DMC and 0.02 mol of cationic hydrophobic monomer C18DMAAC in deionized water, adjust the pH value to 8, purge with nitrogen to remove oxygen and stir for about 30 min. Raise the temperature of the polymerization solution to 50 °C, then add V50 to initiate polymerization, and carry out the polymerization reaction at a constant temperature in a constant temperature water bath for 4 h. Take out, shear, granulate, dry and pulverize to obtain the hydrophobically associating polymer.

[0049] Preparation of polymer mother liquor: Add 0.3 g of hydrophobically associating polymer and 0.36 g of AM / AMPS copolymer to 59.34 g of formation water, stir evenly to fully dissolve the polymer.

[0050] Preparation of mixed crosslinker solution: Add 0.005 g of organic chromium crosslinker and 0.24 g of phenolic aldehyde crosslinker to 19.755 g of formation water, stir evenly.

[0051] Preparation of double-network gel: Add 20 g of mixed crosslinker to 60 g of polymer mother liquor, stir evenly, and react at 130 °C for 3 h to obtain the double-network gel.

[0052] Example 3:

[0053] This example provides a temperature-resistant and salt-resistant double-network gel, and the gel solution comprises the following components:

[0054] 50 g of polymer mother liquor (including 1.5 wt% of hydrophobically associating polymer, 0.6 wt% of AM / AMPS copolymer and water), 20 g of mixed crosslinker (including 0.525 wt% of organic chromium crosslinker, 1.2 wt% of phenolic aldehyde crosslinker).

[0055] The temperature-resistant and salt-resistant double-network gel of this example is prepared by the following method:

[0056] Preparation of hydrophobically associating polymer: Dissolve 1.0 mol of acrylamide, 0.3 mol of betaine monomer, 0.02 mol of salt-tolerant monomer DMC and 0.03 mol of cationic hydrophobic monomer C18DMAAC in deionized water, adjust the pH value to 9, purge with nitrogen to remove oxygen and stir for about 30 min. Raise the temperature of the polymerization solution to 60 °C, then add V061 to initiate polymerization, and carry out the polymerization reaction at a constant temperature in a constant temperature water bath for 3 h. Take out, shear, granulate, dry and pulverize to obtain the hydrophobically associating polymer.

[0057] Preparation of polymer mother liquor: Add 0.75 g of hydrophobically associating polymer and 0.3 g of AM / AMPS copolymer to 48.95 g of formation water, stir evenly to fully dissolve the polymer.

[0058] Preparation of the mixed crosslinking agent solution: Add 0.105 g of organic chromium crosslinking agent and 0.24 g of phenolic aldehyde crosslinking agent to 19.655 g of formation water, and stir evenly.

[0059] Preparation of the double-network gel: Add 20 g of the mixed crosslinking agent to 50 g of the polymer mother liquor, stir evenly, react at 130 °C for 4 h to obtain the double-network gel.

[0060] Example 4:

[0061] This example provides a temperature- and salt-resistant double-network gel. The gel solution comprises the following components:

[0062] 60 g of polymer mother liquor (including 1.5 wt% of hydrophobically associating polymer, 0.2 wt% of AM / AMPS copolymer, and water), 30 g of mixed crosslinking agent (including 0.525 wt% of organic chromium crosslinking agent, 0.4 wt% of phenolic aldehyde crosslinking agent).

[0063] The temperature- and salt-resistant double-network gel of this example is prepared by the following method:

[0064] Preparation of the hydrophobically associating polymer: Dissolve 1.0 mol of acrylamide, 0.2 mol of betaine monomer, 0.05 mol of salt-resistant monomer DMC, and 0.02 mol of cationic hydrophobic monomer C18AM in deionized water, adjust the pH value to 8, purge with nitrogen to remove oxygen and stir for about 30 min, raise the temperature of the polymerization solution to 50 °C, then add V50 to initiate polymerization, and carry out the constant-temperature polymerization reaction in a constant-temperature water bath for 4 h. Take out, shear, granulate, dry, and pulverize to obtain the hydrophobically associating polymer.

[0065] Preparation of the polymer mother liquor: Add 0.9 g of hydrophobically associating polymer and 0.12 g of AM / AMPS copolymer to 58.98 g of formation water, and stir evenly to fully dissolve the polymer.

[0066] Preparation of the mixed crosslinking agent solution: Add 0.1575 g of organic chromium crosslinking agent and 0.12 g of phenolic aldehyde crosslinking agent to 29.7225 g of formation water, and stir evenly.

[0067] Preparation of the double-network gel: Add 30 g of the mixed crosslinking agent to 60 g of the polymer mother liquor, stir evenly, react at 130 °C for 2 h to obtain the double-network gel.

[0068] Example 5:

[0069] This example provides a temperature- and salt-resistant double-network gel. The gel solution comprises the following components:

[0070] 40 g of polymer mother liquor (including 2.5 wt% of hydrophobically associating polymer, 0.2 wt% of AM / AMPS copolymer and formation water), 30 g of mixed crosslinking agent (including 0.125 wt% of organic chromium crosslinking agent, 0.4 wt% of phenolic aldehyde crosslinking agent).

[0071] The temperature-resistant and salt-resistant double-network gel of this example is prepared by the following method:

[0072] Preparation of hydrophobically associating polymer: Dissolve 1.0 mol of acrylamide, 0.2 mol of betaine monomer, 0.05 mol of salt-resistant monomer DMC and 0.02 mol of cationic hydrophobic monomer DiC18DMAA in deionized water, adjust the pH value to 8, purge with nitrogen to remove oxygen and stir for about 30 min, raise the temperature of the polymerization solution to 50 °C, then add V50 to initiate polymerization, carry out the polymerization reaction at a constant temperature in a constant-temperature water bath for 3 h, take out, shear, granulate, dry, pulverize, and thus obtain the hydrophobically associating polymer.

[0073] Preparation of polymer mother liquor: Add 1.0 g of hydrophobically associating polymer and 0.08 g of AM / AMPS copolymer to 38.92 g of formation water, stir evenly to fully dissolve the polymer.

[0074] Preparation of mixed crosslinking agent solution: Add 0.0375 g of organic chromium crosslinking agent and 0.12 g of phenolic aldehyde crosslinking agent to 29.8425 g of formation water, stir evenly.

[0075] Preparation of double-network gel: Add 30 g of mixed crosslinking agent to 40 g of polymer mother liquor, stir evenly, react at 130 °C for 3 h to obtain the double-network gel.

[0076] Comparative example:

[0077] This example provides a gel, and the gel solution includes the following components:

[0078] 60 g of polymer mother liquor (1.0 wt% of AM / AMPS copolymer and water), 20 g of mixed crosslinking agent (2.0 wt% of phenolic aldehyde crosslinking agent).

[0079] The temperature-resistant and salt-resistant double-network gel of this example is prepared by the following method:

[0080] Preparation of polymer mother liquor: Add 0.6 g of AM / AMPS copolymer to 59.4 g of formation water, stir evenly to fully dissolve the polymer.

[0081] Preparation of crosslinking agent solution: Add 0.4 g of phenolic aldehyde crosslinking agent to 19.6 g of formation water, stir evenly.

[0082] Preparation of the gel: Add 20 g of the mixed crosslinking agent to 60 g of the polymer mother liquor, stir evenly, and react at 130 °C for 3 h to obtain the gel.

[0083]

[0084] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Therefore, the above description is only an embodiment of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention also includes various equivalent changes and improvements, and these changes and improvements will all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a hydrophobically associating polymer, characterized in that, it includes the following: Under an inert atmosphere, mix acrylamide monomer, betaine monomer, salt-tolerant monomer and cationic hydrophobic monomer, adjust the pH to alkaline, add an azo initiator after heating, and obtain the hydrophobically associating polymer after reaction.

2. The preparation method of the hydrophobically associating polymer according to claim 1, characterized in that, the molar ratio of the acrylamide monomer, the betaine monomer, the salt-tolerant monomer and the cationic hydrophobic monomer is 1:(0.1 - 0.3):(0.02 - 0.08):(0.01 - 0.03).

3. The preparation method of the hydrophobically associating polymer according to any one of claims 1 - 2, characterized in that, the betaine monomer is 2-((3-methacrylamidopropyl)dimethylamine) acetate.

4. The preparation method of the hydrophobically associating polymer according to any one of claims 1 - 3, characterized in that, the salt-tolerant monomer is one or more of methacryloyloxyethyl trimethyl ammonium chloride, dimethyldiallyl ammonium chloride, acryloyloxyethyl trimethyl ammonium chloride, allyl trimethyl ammonium chloride, methacrylamide ethyl trimethyl ammonium chloride and methacryloyloxyethyl dimethyl benzyl ammonium chloride.

5. The preparation method of the hydrophobically associating polymer according to any one of claims 1 - 4, characterized in that, the cationic hydrophobic monomer is one or more of N,N-dimethyl(dodecyl - docosyl)allyl ammonium chloride, N-(dodecyl - docosyl)acrylamide, bis(dodecyl - docosyl)methylallyl ammonium chloride.

6. The preparation method of the hydrophobically associating polymer according to any one of claims 1 - 5, characterized in that, the azo initiator is water-soluble azo V-044, water-soluble azo V50 or water-soluble azo V061.

7. The preparation method of the hydrophobically associating polymer according to any one of claims 1 - 6, characterized in that, adjust the pH to 7 - 9.

8. A hydrophobically associating polymer, characterized in that, the hydrophobically associating polymer is the hydrophobically associating polymer prepared by the preparation method according to any one of claims 1 - 7.

9. A preparation method of a gel, characterized in that, it includes the following: Stir and mix the polymer mother liquor and the mixed crosslinking agent solution until crosslinked; Wherein, the polymer mother liquor includes 0.5wt% - 2.5wt% of the hydrophobically associating polymer and 0.2wt% - 1wt% of the AM / AMPS copolymer, and the rest is water. The hydrophobically associating polymer is the hydrophobically associating polymer according to claim 8, AM is acrylamide, AMPS is 2-acrylamido-2-methylpropanesulfonic acid, and the AM / AMPS copolymer is the copolymer of the two. The mixed crosslinking agent solution includes: 0.4wt% - 2wt% phenolic aldehyde crosslinking agent solution and 0.025wt% - 0.125wt% organic chromium crosslinking agent solution.

10. A gel, characterized in that, the gel is the gel prepared by the preparation method according to claim 9.

Images