CN111363073A - Amphiphilic polymer with anti-swelling and flocculation effects and preparation method and application thereof - Google Patents

Abstract

The invention discloses an amphiphilic polymer with anti-swelling and flocculation effects and a preparation method and application thereof, and particularly relates to macromolecular polyacrylic acyloxy ethyl-N, N, N-dimethyl octyl ammonium bromide (PASC8) with a hydrophobic head group and high charge density, wherein the structural formula of the macromolecular polyacrylic acyloxy ethyl-N, N, N-dimethyl octyl ammonium bromide is shown as a formula I. The polymer adsorbs bentonite particles in a bentonite water dispersion liquid through electrostatic action, damages the stability of a dispersion system, simultaneously, each structural unit is provided with a hydrophobic chain, the solid/liquid phase separation process is promoted to a certain extent, and the polymer has a good flocculation effect, so that clay dispersion and particle migration are inhibited, and the effect of stabilizing the clay and the particles is achieved. In another aspect, PASC₈Can be intercalated into bentonite molecules to reduce the swelling of the bentonite particles due to hydration by electrostatic action. The polymer prepared by the method is expected to be obviously improved when being applied to the oil exploitation processAnd (4) oil recovery.

Description

Amphiphilic polymer with anti-swelling and flocculation effects and preparation method and application thereof

Technical Field

The invention belongs to the field of polymers, and particularly relates to an amphiphilic high-charge-density polymer, a preparation method thereof and application thereof as an anti-swelling agent and a flocculating agent for a bentonite aqueous solution.

Background

In the process of oil exploitation, water enters underground, and pore throats are blocked due to dispersion and migration of generated clay, so that the oil extraction rate is greatly influenced. The polymer clay stabilizer is one of the very important chemical treating agents for ensuring the stability of well wall, shortening well drilling period, reducing well drilling cost and improving oil gas yield. The cationic polymer with high charge density is strongly chemisorbed by electrostatic attraction between positive charge groups on a macromolecular chain and clay particles with negative charges, so that the dispersion of the clay and the migration of the particles are inhibited, the effect of stabilizing the clay and the particles is achieved, and the effect of a good clay stabilizer is achieved.

Disclosure of Invention

It is an object of the present invention to provide an amphiphilic polymer PASC having a hydrophobic head group and having a high charge density₈。

The amphiphilic polymer PASC provided by the invention₈The structure of the repeating unit is shown as formula II:

the amphiphilic polymer PASC provided by the invention₈The structural formula of (A) is shown in formula I:

the molecular weight of the polymer is not strictly required in the invention, such as 1000, 5000, 10000, 11500, 20000, 50000 and the like.

The invention provides an amphiphilic polymer PASC with a hydrophobic head group and high charge density₈The adsorption of bentonite particles in bentonite suspension by its electrostatic action plays a major role in the disruption of dispersion stability, while each building block has a hydrophobic chain, which promotes the solid/liquid phase separation process to some extent. In another aspect, PASC₈Can be intercalated into bentonite molecules, and the expansion degree of bentonite particles due to hydration is reduced through electrostatic interaction.

It is another object of the present invention to provide the amphiphilic polymer PASC₈The preparation method of (1).

The amphiphilic polymer PASC provided by the invention₈The preparation method comprises the following steps:

1) synthesis of the monomer Acryloxyethyl-N, N, N-Dimethyloctylalkylammonium Bromide (ASC)₈): reacting N, N-dimethylaminoethyl acrylate with octyl bromide to obtain a monomer acryloyloxyethyl-N, N, N-dimethyl octyl ammonium bromide;

2) adopting azodiisobutyronitrile as an initiator, and reacting the monomer of acryloyloxyethyl-N, N, N-dimethyl octyl ammonium bromide (ASC)₈) Free radical polymerization reaction is carried out to obtain amphiphilic polymer PASC shown as formula I₈。

In step 1) of the above method, the molar ratio of the N, N-dimethylaminoethyl acrylate to the octyl bromide is 1:1.2-2 (preferably 1: 1.2-1.5); the reaction is carried out in a solvent, which may be acetone. The reaction conditions of the reaction are as follows: stirring is carried out at 40-60 ℃ for 5-12 hours, preferably at 40-45 ℃ for 5-6 hours.

The method step 1) further comprises: after the reaction is finished, cooling the reaction system to below 30 ℃ and adding diethyl ether.

In step 2), the reaction conditions of the radical polymerization reaction are as follows: adding azodiisobutyronitrile into water at 60-70 ℃, and stirring for reaction for 6-12 hours; the dosage of the azodiisobutyronitrile is 1-3% of the monomer ASC8 by mass.

The method step 2) further comprises: dissolving the obtained polymer product with secondary water after the reaction is finished, filling the solution into a dialysis bag, dialyzing in the secondary water for one week, and freeze-drying to obtain a white solid sample PASC₈。

It is still another object of the present invention to provide the amphiphilic polymer PASC₈The use of (1).

The application provided by the invention is the application of the anti-swelling agent and/or the flocculant.

In some embodiments, the target of action can be bentonite aqueous solution, and in practical application, the invention is applicable to various negatively charged clay solutions.

Compared with the prior art, the invention has the following beneficial effects: the amphiphilic polymer PASC synthesized by the invention₈The adsorption of bentonite particles in bentonite suspension by its electrostatic action plays a major role in the disruption of dispersion stability, while each building block has a hydrophobic chain, which promotes the solid/liquid phase separation process to some extent. In another aspect, PASC₈Can be intercalated into bentonite molecules, and the expansion degree of bentonite particles due to hydration is reduced through electrostatic interaction. The amphiphilic polymer is applied to the oil exploitation process, and is expected to obviously improve the oil recovery ratio.

Drawings

FIG. 1 is the PASC prepared in example 1₈Is/are as follows¹The H NHR spectrum and the signal attribution of each proton.

FIG. 2 is a graph showing flocculation of an aqueous dispersion of bentonite clay by different concentrations of amphiphilic polymer in example 1 of the present invention.

FIG. 3 is a graph showing turbidity measurements of amphiphilic polymers at different concentrations in example 1 of the present invention.

FIG. 4 is a Zeta potential test chart of amphiphilic polymer of example 1 of the present invention at different concentrations.

FIG. 5 is a graph showing the anti-swelling test of amphiphilic polymers at different concentrations in example 2 of the present invention.

Detailed Description

The present invention is described below with reference to specific embodiments, but the present invention is not limited thereto, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

The experimental procedures used in the following examples are all conventional procedures unless otherwise specified.

Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The quantitative experiments referred to in the examples below, all set at least 3 replicates and the results were averaged.

Example 1 Synthesis of amphiphilic Polymer PASC₈

Firstly synthesizing a monomer of acryloyloxyethyl-N, N, N-dimethyl octyl ammonium bromide (ASC8), putting N, N-dimethyl amino ethyl acrylate and octyl bromide into a round-bottom flask according to the molar ratio of 1:1.2, taking acetone as a solvent, stirring for 5 hours at 45 ℃, cooling, dropwise adding diethyl ether to separate out a white solid, repeatedly washing with diethyl ether to finally obtain the white solid ASC₈. Then, free radical polymerization is carried out (in water, at 70 ℃, azobisisobutyronitrile (3 percent of the mass of monomer ASC8) is added), stirring and reaction are carried out for 6 hours, the polymerization product is dissolved by secondary water, the solution is filled into a dialysis bag and dialyzed in the secondary water for one week, and a white solid sample PASC is obtained after freeze drying₈The structural formula is shown as formula I. Its molecular weight is about 11500.

The structure identification results are shown in FIG. 1. FIG. 1 is PASC₈Is/are as follows¹The H NHR spectrum and the signal attribution of each proton. H_aAnd H_b、H_cRespectively in surfactant structural unitChemical shift signals of the terminal methyl and methylene hydrogen protons of the long alkyl carbon chain of (2), H_e、H_dAnd H_fChemical shift signals for the methyl and methylene protons attached to the quaternary ammonium salt nitrogen atom, respectively. There is no chemical shift signal for unsaturated hydrogens, but for polymer backbone hydrogens, indicating that the monomer has reacted or been removed during dialysis.

The obtained substance is determined to be the target polymer through structural identification.

Samples were prepared as aqueous solutions of varying concentrations. As shown in FIG. 2, 5ml of 1.5g/L aqueous dispersion of bentonite was present in each sample bottle, and different masses of PASC were added₈Adding into water dispersion to make PASC₈Was 0, 10, 20, 50, 100, 200, 500, 1000mg/L, and the light transmittance of the supernatant was measured at a wavelength of 450nm using a turbidimeter (PC920, Brinkmann, Germany).

As shown in FIG. 2, when the polymer concentration reached 10mg/L, the bentonite aqueous dispersion showed significant sedimentation flocculation, and the supernatant transmittance reached 82%, and when the polymer concentration reached 20mg/L, the bentonite aqueous dispersion further sedimented and flocculated, and the supernatant transmittance was close to 100%. Showing good flocculation effect. The results of the turbidity test are shown in FIG. 3.

The silica dispersions and polymer solutions prepared in the turbidity experiments were likewise used in the Zeta potential experiments. The instrument used was a Malvern particle sizer (Nano-ZS, Malvern, England). The Zeta potential test chart is shown in FIG. 4. The polyelectrolyte concentration is increased so that the Zeta potential changes gradually from an initial negative value to a positive value, because the cationic polymer molecular chains with positive charges gradually adsorb to the surface of the silica particles with negative charges, and electrostatic interaction occurs, so that the potential changes from negative to positive. When PASC₈When the concentration is increased to 50mg/L, the isoelectric concentration is reached, which is mutually confirmed by the flocculation phenomenon in FIG. 2. Demonstrates the synthetic PASC₈Has high charge density, and can effectively flocculate the bentonite water dispersion liquid through electrostatic action.

Example 2 Synthesis of amphiphilic Polymer PASC₈

Mixing N, N-diAdding methyl amino ethyl acrylate and octyl bromide into a round-bottom flask according to the molar ratio of 1:1.5, taking acetone as a solvent, stirring for 6 hours at 40 ℃, cooling, dropwise adding diethyl ether, separating out a white solid, and repeatedly washing with diethyl ether to finally obtain a white solid ASC₈. Then carrying out free radical polymerization (in water, at 60 ℃, adding azobisisobutyronitrile (1% of monomer ASC8 by mass), stirring and reacting for 12 hours, using azobisisobutyronitrile as an initiator, dissolving a polymerization product with secondary water, filling the solution into a dialysis bag, dialyzing for one week in the secondary water, and freeze-drying to obtain a white solid sample PASC₈。

The obtained substance is determined to be the target polymer through structural identification.

The anti-swelling effect of the synthesized product is determined by a centrifugal method. Amphiphilic polymer PASC₈Preparing solutions with different concentrations, weighing 0.5g of bentonite, putting into a 10mL centrifuge tube, adding 10mL of clay stabilizer solutions with different concentrations, shaking up sufficiently, standing for 2h at room temperature, putting into a centrifuge, and centrifuging at the rotation speed of 1500r/min for 15 min.

The samples in the anti-swelling test were freeze-dried. The change in interlayer spacing of bentonite was measured by X-ray diffraction. The scattering angle ranges from 2 ° to 8 °. As can be seen from Table 1, after soaking in water, the interlayer spacing of bentonite increases significantly due to hydration

While the interlayer spacing of the bentonite gradually decreases with the increase of the concentration of PASC8, and when the concentration reaches 3000mg/L, the interlayer spacing is only

Demonstration of the synthesized PASC₈Has effective anti-swelling effect.

TABLE 1 interlamellar spacing of Bentonite particles under the action of amphiphilic polymers at different concentrations

Claims (10)

1. A compound having the structure shown in formula II:

2. a process for the preparation of a compound according to claim 1, comprising the steps of: and reacting the N, N-dimethylaminoethyl acrylate with the octyl bromide to obtain the product.

3. The method of claim 2, wherein: the molar ratio of the N, N-dimethylaminoethyl acrylate to the bromooctane is 1:1.2-2, preferably 1: 1.2-1.5;

the reaction is carried out in a solvent, wherein the solvent is acetone; the reaction conditions of the reaction are as follows: stirring is carried out at 40-60 ℃ for 5-12 hours, preferably at 40-45 ℃ for 5-6 hours.

4. The production method according to claim 2 or 3, characterized in that: the method step 1) further comprises: after the reaction is finished, cooling the reaction system to below 30 ℃ and adding diethyl ether.

5. An amphiphilic polymer of formula I:

6. a process for the preparation of an amphiphilic polymer according to claim 5 comprising the steps of:

and (2) carrying out free radical polymerization reaction by using azodiisobutyronitrile as an initiator and using a compound shown as a formula II as a monomer to obtain the amphiphilic compound shown as the formula I.

7. The method of claim 6, wherein: the reaction conditions of the free radical polymerization reaction are as follows: adding azodiisobutyronitrile into water at 60-70 ℃, and stirring for reaction for 6-12 hours; the dosage of the azodiisobutyronitrile is 1-3% of the monomer ASC8 by mass.

8. The production method according to claim 6 or 7, characterized in that: the method step 2) further comprises: and after the reaction is finished, dissolving the obtained polymerization product by using secondary water, filling the solution into a dialysis bag, dialyzing in the secondary water for one week, and freeze-drying to obtain a white solid sample.

9. Use of an amphiphilic polymer according to claim 5 in the preparation of an anti-swelling and/or flocculating agent.

10. Use according to claim 9, characterized in that: the object of the action of the flocculating agent is negatively charged clay solution;

or the object acted by the anti-swelling agent is negatively charged clay solution.

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