Viscoelastic polymer type self-assembly plugging agent and preparation method thereof

Abstract

The invention relates to the technical field of plugging agents, and discloses a viscoelastic polymer type self-assembly plugging agent and a preparation method thereof. The preparation method comprises the following steps: adding acrylamide, butyl acrylate, 2-acrylamide-2-methylpropanesulfonic acid, quaternized cyclodextrin, gamma-glycidyl ether oxypropyl trimethoxy silane modified bentonite, Schiff base styrene, a sodium dodecyl benzene sulfonate emulsifier and octadecyl dimethyl allyl ammonium chloride into a reaction kettle; and adding an azodiisobutyronitrile initiator into the deionized water, uniformly mixing, and reacting for 4-5 hours at 50-65 DEG C to obtain the viscoelastic polymer type self-assembled plugging agent after the reaction is finished. The plugging agent disclosed by the invention has a relatively good plugging effect, and effectively solves the problem that the gel strength is weakened or the gelling is not thorough due to the formation shearing effect in a continuous gel migration process.

Description

Technical Field

[0001] The invention relates to the technical field of plugging agents, in particular to a viscoelastic polymer self-assembly plugging agent and a preparation method thereof. Background Art

[0002] In the process of oil field development, with the deepening of water injection development, the problem of excessive water absorption of high permeability layer and insufficient water absorption of low permeability layer caused by formation heterogeneity has become increasingly prominent, seriously affecting the recovery rate of oil fields. For this reason, water plugging and profile control technology has become one of the key measures to improve crude oil recovery by injecting plugging agents into the formation, selectively blocking the water flow channel of the high permeability layer, and improving the water absorption profile. During the injection process of traditional plugging agents (such as polyacrylamide gels), the gel network is easily dissociated due to the shear effect of the formation fluid, resulting in a significant decrease in gel strength or even complete failure, and poor environmental adaptability. Therefore, how to avoid such a phenomenon is the key to solving the problem. For example, the Chinese patent application with publication number CN10683573B applies for a plugging agent and its preparation method and application. The plugging agent provided by the invention can realize the reuse of silicon mud and aged oil resources. At the same time, the prepared plugging agent has good properties such as temperature resistance and salt resistance, but its self-assembly effect needs to be improved. Summary of the invention

[0003] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a viscoelastic polymer self-assembling plugging agent and a preparation method thereof, which has a good plugging effect and effectively solves the problem of weakening of gel strength or incomplete gelation caused by formation shear during continuous gel migration.

[0004] (II) Technical solution To achieve the above object, the present invention provides the following technical scheme: a viscoelastic polymer self-assembly plugging agent, comprising the following components by weight: 3-5 parts by weight of acrylamide, 4-6 parts by weight of butyl acrylate, 2-6 parts by weight of 2-acrylamide-2-methylpropane sulfonic acid, 2-5 parts by weight of quaternized cyclodextrin, 3-4 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite, 2-3 parts by weight of Schiff base styrene, 0.02-0.03 parts by weight of sodium dodecylbenzene sulfonate emulsifier, 0.6-0.8 parts by weight of octadecyl dimethyl allyl ammonium chloride, and 0.01-0.03 parts by weight of azobisisobutyronitrile initiator.

[0005] Furthermore, the preparation method of the quaternized cyclodextrin is: S1. Add 0.9-1g of β-cyclodextrin and 0.35-0.36g of sodium hydroxide to 45-60mL of water, then add 1.14-1.22g of allyl glycidyl ether, stir and react at 25-28°C for 8-10h, then add 4% hydrochloric acid to neutralize to pH 7-7.5, filter, wash, and obtain allyloxy-cyclodextrin; S2. Add allyloxy-cyclodextrin and 2,3-epoxypropyltrimethylammonium chloride to a mixed solution of 30-35 mL of dimethyl sulfoxide and 20-25 mL of water, stir to dissolve, continue to add potassium carbonate, react at 45-60°C for 4-8 hours, dialyze and wash after completion to obtain quaternary ammonium cyclodextrin.

[0006] Furthermore, the mass fraction of sodium hydroxide in S1 is 5-8%.

[0007] Furthermore, the molar ratio of allyloxy-cyclodextrin, 2,3-epoxypropyltrimethylammonium chloride and potassium carbonate in S2 is 1 mmol:3.2-3.6 mmol:0.01-0.012 mmol.

[0008] Furthermore, the preparation method of the Schiff base styrene is: add glutamic acid and 4-vinylbenzaldehyde to 45-60 mL of N,N-dimethylformamide solvent, stir to dissolve, then heat to 60-70 ° C, stir and reflux for 7-10 hours, and after the reaction, use 0.2 g of anhydrous MgSO 4 The generated water was absorbed, washed with ether, and then the crude product was recrystallized from ethanol to obtain Schiff base styrene.

[0009] Furthermore, the molar ratio of the glutamic acid to 4-vinylbenzaldehyde is 1.2-1.4:1.

[0010] Furthermore, the preparation method of the viscoelastic polymer self-assembly plugging agent is as follows: acrylamide, butyl acrylate, 2-acrylamide-2-methylpropane sulfonic acid, quaternized cyclodextrin, γ-glycidyloxypropyltrimethoxysilane modified bentonite, Schiff base styrene, sodium dodecylbenzenesulfonate emulsifier, octadecyldimethylallyl ammonium chloride, and azobisisobutyronitrile initiator are added into deionized water, mixed evenly, reacted at 50-65° C. for 4-5 hours, and then a viscoelastic polymer self-assembly plugging agent is obtained.

[0011] 3. Beneficial technical effects The invention adds acrylamide, butyl acrylate, 2-acrylamide-2-methylpropane sulfonic acid, quaternized cyclodextrin, γ-glycidyloxypropyltrimethoxysilane modified bentonite, Schiff base styrene, sodium dodecylbenzenesulfonate emulsifier, octadecyldimethylallylammonium chloride and azobisisobutyronitrile initiator into deionized water, mixes evenly, reacts at 50-65°C for 4-5h, and obtains a viscoelastic polymer self-assembly plugging agent after reaction.

[0012] The plugging agent of the present invention forms a dual mechanism of "shear-self-healing" by introducing dynamic covalent bonds (Schiff base styrene) and viscoelastic networks (quaternized cyclodextrin / acrylamide composite system). Schiff base styrene is dynamically cross-linked through imine bonds, combined with the hydrophobic association of quaternized cyclodextrin, to form a "rigid skeleton-elastic network" composite structure. When the gel is damaged by external forces, the dynamic bonds can be recombined to achieve self-assembly. It has a good plugging effect. Modified bentonite: The surface hydroxyl groups of bentonite modified by γ-glycidyloxypropyltrimethoxysilane are converted into epoxy groups, forming ionic-covalent synergistic crosslinking with quaternary ammonium salts, improving the density of the gel network and achieving a good plugging effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the reaction process of quaternary ammonium cyclodextrin.

[0014] Figure 2 It is the nuclear magnetic hydrogen spectrum of the quaternized cyclodextrin in Example 1.

[0015] Figure 3 This is the H NMR spectrum of the Schiff base styrene in Example 1. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are 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.

[0017] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific embodiments of the specification.

[0018] KH560 modified bentonite was prepared according to the literature "Adsorption performance of tetraethylenepentamine-grafted bentonite on acid red GR" (Chemical Industry Progress, Vol. 40, No. 5, 2021): Add 2 g of bentonite to 100 mL of 7% hydrochloric acid solution, heat and reflux at 80 ° C for acidification, filter, wash with deionized water and dry to obtain acid-modified bentonite. Disperse 2 g of acid-modified bentonite in 150 mL of ethanol, add 8 g of γ-glycidyloxypropyltrimethoxysilane, stir and reflux at 90 ° C in a nitrogen atmosphere for 24 hours, filter, wash with ethanol and dry to obtain γ-glycidyloxypropyltrimethoxysilane-modified bentonite. Example 1

[0019] S1. Add 0.9 g of β-cyclodextrin and 0.35 g of sodium hydroxide with a mass fraction of 5% to 45 mL of water, then add 1.14 g of allyl glycidyl ether, stir and react at 25°C for 8 h, then add hydrochloric acid to neutralize to pH 7, filter, wash, and obtain allyloxy-cyclodextrin; S2. Add 1 mmol of allyloxy-cyclodextrin and 3.2 mmol of 2,3-epoxypropyltrimethylammonium chloride to a mixed solution of 30 mL of dimethyl sulfoxide and 20 mL of water, stir to dissolve, continue to add 0.01 mmol of potassium carbonate, react at 45 ° C for 4 h, dialyze after completion, wash, and obtain quaternary ammonium cyclodextrin; S3. Add 1.2 mmol of glutamic acid and 1 mmol of 4-vinylbenzaldehyde to 45 mL of N,N-dimethylformamide solvent, stir to dissolve, then heat to 60 °C and reflux for 7 h. After the reaction, add 0.2 g of anhydrous MgSO 4 The generated water was absorbed, washed with ether, and then the crude product was recrystallized from ethanol to obtain Schiff base styrene;

[0020] S4. Add 3 parts by weight of acrylamide, 4 parts by weight of butyl acrylate, 2 parts by weight of 2-acrylamide-2-methylpropane sulfonic acid, 2 parts by weight of quaternized cyclodextrin, 3 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite, 2 parts by weight of Schiff base styrene, 0.02 parts by weight of sodium dodecylbenzenesulfonate emulsifier, 0.6 parts by weight of octadecyldimethylallyl ammonium chloride, and 0.01 parts by weight of azobisisobutyronitrile initiator into 25 parts by weight of deionized water, mix well, and react at 50°C for 4 hours to obtain a viscoelastic polymer self-assembly plugging agent. Example 2

[0021] S1. Add 1 g of β-cyclodextrin and 0.36 g of sodium hydroxide with a mass fraction of 8% to 60 mL of water, then add 1.22 g of allyl glycidyl ether, stir and react at 28°C for 10 h, then add hydrochloric acid to neutralize to pH 7.5, filter, wash, and obtain allyloxy-cyclodextrin; S2. Add 1 mmol of allyloxy-cyclodextrin and 3.6 mmol of 2,3-epoxypropyltrimethylammonium chloride to a mixed solution of 35 mL of dimethyl sulfoxide and 25 mL of water, stir to dissolve, continue to add 0.012 mmol of potassium carbonate, react at 60 ° C for 8 h, dialyze after completion, wash, and obtain quaternary ammonium cyclodextrin; S3. Add 1.4 mmol of glutamic acid and 1 mmol of 4-vinylbenzaldehyde to 60 mL of N,N-dimethylformamide solvent, stir to dissolve, then heat to 70 °C and reflux for 10 h. After the reaction, add 0.2 g of anhydrous MgSO 4 The generated water was absorbed, washed with ether, and then the crude product was recrystallized from ethanol to obtain Schiff base styrene; S4. Add 5 parts by weight of acrylamide, 6 parts by weight of butyl acrylate, 6 parts by weight of 2-acrylamide-2-methylpropane sulfonic acid, 5 parts by weight of quaternized cyclodextrin, 4 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite, 3 parts by weight of Schiff base styrene, 0.03 parts by weight of sodium dodecylbenzenesulfonate emulsifier, 0.8 parts by weight of octadecyldimethylallyl ammonium chloride, and 0.03 parts by weight of azobisisobutyronitrile initiator into 30 parts by weight of deionized water, mix well, and react at 65°C for 5 hours to obtain a viscoelastic polymer self-assembly plugging agent. Example 3

[0022] S1. Add 0.95 g of β-cyclodextrin and 0.36 g of sodium hydroxide with a mass fraction of 6% to 50 mL of water, then add 1.18 g of allyl glycidyl ether, stir and react at 26°C for 9 h, then add hydrochloric acid to neutralize to pH 7.2, filter, wash, and obtain allyloxy-cyclodextrin; S2. Add 1 mmol of allyloxy-cyclodextrin and 3.4 mmol of 2,3-epoxypropyltrimethylammonium chloride to a mixed solution of 32 mL of dimethyl sulfoxide and 22 mL of water, stir to dissolve, continue to add 0.011 mmol of potassium carbonate, react at 50 ° C for 6 h, dialyze after completion, wash, and obtain quaternary ammonium cyclodextrin; S3. Add 1.3 mmol of glutamic acid and 1 mmol of 4-vinylbenzaldehyde to 50 mL of N,N-dimethylformamide solvent, stir to dissolve, then heat to 65 °C and reflux for 8 h. After the reaction, add 0.2 g of anhydrous MgSO 4 The generated water was absorbed, washed with ether, and then the crude product was recrystallized from ethanol to obtain Schiff base styrene; S4. Add 4 parts by weight of acrylamide, 5 parts by weight of butyl acrylate, 4 parts by weight of 2-acrylamide-2-methylpropane sulfonic acid, 4 parts by weight of quaternized cyclodextrin, 3 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite, 2.5 parts by weight of Schiff base styrene, 0.025 parts by weight of sodium dodecylbenzenesulfonate emulsifier, 0.7 parts by weight of octadecyldimethylallyl ammonium chloride, and 0.02 parts by weight of azobisisobutyronitrile initiator into 27 parts by weight of deionized water, mix well, and react at 55°C for 4 hours to obtain a viscoelastic polymer self-assembly plugging agent.

[0023] Comparative Example 1 Compared with Example 3, this comparative example is different in that allyloxy-cyclodextrin is used instead of quaternary ammonium cyclodextrin.

[0024] Comparative Example 2 Compared with Example 3, this comparative example is different in that 4-vinylbenzaldehyde is used instead of Schiff base styrene.

[0025] Comparative Example 3 Compared with Example 3, this comparative example is different in that no quaternary ammonium cyclodextrin is added.

[0026] Comparative Example 4 Compared with Example 3, this comparative example is different in that no Schiff base styrene is added.

[0027] Plugging performance evaluation: The mass concentration of the plugging agent in Examples 1-3 and Comparative Examples 1-4 was 4000 mg / L, and was used at an injection volume of 0.5 PV (ie, the volume of injected liquid was 50% of the pore volume of the formation).

[0028] Viscosity: According to GB / T 12005.2-1989 “Determination of viscosity of polymer solutions”, method: NDJ-8S rotational viscometer, 6 r / min, 25°C.

[0029] Shear resistance: According to the national standard: SY / T 6300-2016 "Determination of rheological parameters of oilfield chemicals", method: Haake Mars III rheometer, 10000 s⁻¹ shear 30 min, 60℃.

[0030] Plugging strength: According to the national standard: SY / T 5590-2016 "General Technical Conditions for Clay Stabilizers for Oilfield Water Injection", method: 30 cm core (permeability 200×10⁻³ μm²), inject 0.5 PV plugging agent, age at 60℃ for 24 hours and then water flood.

[0031] Self-assembly strength: According to the national standard: GB / T 27945-2011 "Cross-linked polymer solutions for polymer flooding", method: TA Instruments ARES-G2 rheometer, strain scanning at 70°C.

[0032] Table 1: Plugging test.

[0033] project Initial viscosity (mPa·s) Shear resistance retention rate (%) Blockage rate (%) Self-assembly strength (Pa) Example 1 41.5 83 92.1 <![CDATA[9.2×10 4 ]]> Example 2 41.6 85 93.6 <![CDATA[9.5×10 4 ]]> Example 3 40.8 82 91.7 <![CDATA[9.3×10 4 ]]> Comparative Example 1 43.9 61 80.5 <![CDATA[8.1×10 4 ]]> Comparative Example 2 42.8 63 82.4 <![CDATA[7.8×10 4 <!-- 4 -->]]> Comparative Example 3 45.7 53 50.4 <![CDATA[5.2×10 4 ]]> Comparative Example 4 46.2 56 52.6 <![CDATA[5.1×10 4 ]]> It can be seen from Table 1 that Examples 1-3 of the present invention have better blocking properties and better self-assembly effects than Comparative Examples 1-4.

[0034] It should be noted that, in this article, the term "comprises", "includes" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0036] Those skilled in the art should understand that the above descriptions are only some specific implementations of the present invention, rather than all embodiments.

Claims

1. A viscoelastic polymer self-assembly plugging agent, characterized in that: The invention comprises the following components by weight: 3-5 parts by weight of acrylamide, 4-6 parts by weight of butyl acrylate, 2-6 parts by weight of 2-acrylamide-2-methylpropane sulfonic acid, 2-5 parts by weight of quaternized cyclodextrin, 3-4 parts by weight of γ-glycidyloxypropyltrimethoxysilane modified bentonite, 2-3 parts by weight of Schiff base styrene, 0.02-0.03 parts by weight of sodium dodecylbenzene sulfonate emulsifier, 0.6-0.8 parts by weight of octadecyl dimethyl allyl ammonium chloride, and 0.01-0.03 parts by weight of azobisisobutyronitrile initiator.

2. The viscoelastic polymer self-assembly plugging agent according to claim 1, characterized in that: The preparation method of the quaternized cyclodextrin is: S1. Add 0.9-1 g of β-cyclodextrin and 0.35-0.36 g of sodium hydroxide to 45-60 mL of water, then add 1.14-1.22 g of allyl glycidyl ether, stir and react at 25-28 ° C for 8-10 hours, then add hydrochloric acid to neutralize to pH 7-7.5, filter, wash, and obtain allyloxy-cyclodextrin; S2. Add allyloxy-cyclodextrin and 2,3-epoxypropyltrimethylammonium chloride to a mixed solution of 30-35 mL of dimethyl sulfoxide and 20-25 mL of water, stir to dissolve, continue to add potassium carbonate, react at 45-60°C for 4-8 hours, dialyze and wash after completion to obtain quaternary ammonium cyclodextrin.

3. The viscoelastic polymer self-assembly plugging agent according to claim 2, characterized in that: The mass fraction of sodium hydroxide in the S1 is 5-8%.

4. The viscoelastic polymer self-assembly plugging agent according to claim 2, characterized in that: The molar ratio of allyloxy-cyclodextrin, 2,3-epoxypropyltrimethylammonium chloride and potassium carbonate in S2 is 1 mmol:3.2-3.6 mmol:0.01-0.012 mmol.

5. The viscoelastic polymer self-assembly plugging agent according to claim 1, characterized in that: The preparation method of the Schiff base styrene is as follows: glutamic acid and 4-vinylbenzaldehyde are added to 45-60 mL of N,N-dimethylformamide solvent, stirred to dissolve, then heated to 60-70° C. and stirred and refluxed for 7-10 hours, after the reaction, 0.2 g of anhydrous MgSO4 is used to absorb the generated water, washed with ether, and then the crude product is recrystallized with ethanol to obtain the Schiff base styrene.

6. The viscoelastic polymer self-assembly plugging agent according to claim 5, characterized in that: The molar ratio of the glutamic acid to 4-vinylbenzaldehyde is 1.2-1.4 mmol:1 mmol.

7. A method for preparing the viscoelastic polymer self-assembly plugging agent according to any one of claims 1 to 6, characterized in that: The preparation method of the viscoelastic polymer self-assembly plugging agent is as follows: acrylamide, butyl acrylate, 2-acrylamide-2-methylpropane sulfonic acid, quaternized cyclodextrin, γ-glycidyloxypropyltrimethoxysilane modified bentonite, Schiff base styrene, sodium dodecylbenzenesulfonate emulsifier, octadecyldimethylallyl ammonium chloride, and azobisisobutyronitrile initiator are added into deionized water, mixed evenly, reacted at 50-65° C. for 4-5 hours, and then the viscoelastic polymer self-assembly plugging agent is obtained.

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