PH response type ionic-nonionic segmented copolymer dispersing agent as well as preparation method and application thereof

Abstract

The invention relates to a pH response type ionic-nonionic segmented copolymer dispersing agent and a preparation method and application thereof.The preparation method comprises the steps that firstly, a nonionic polymer is prepared from an RAFT chain transfer agent and a monomer acryloyl morpholine (ACMO), then two ionic monomers including methacrylic acid (MAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) are embedded, and the pH response type ionic-nonionic segmented copolymer dispersing agent is obtained; a block polymer is formed with ionic and non-ionic distinguishing. The prepared pH response type ionic-nonionic polymer has different turbidity and surface activity under different pH values under the influence of the pH value, can be used as a dispersing agent of micro manganese and other weighting materials, obviously prolongs the static settling suspension effect, and reduces the particle size.

Description

Technical Field

[0001] The invention relates to a pH-responsive ionic-nonionic block copolymer dispersant and a preparation method and application thereof, belonging to the technical field of preparation of dispersants for weighting materials in drilling fluids and completion fluids. Background Art

[0002] With the continuous progress of oil production, high-density and ultra-high-density drilling fluid systems are used in more complex terrain environments. Therefore, the stability requirements for drilling fluids are constantly increasing. Commonly used weighting agents include barite, ultrafine calcium carbonate, iron ore powder, micro-manganese ore powder, etc. Several weighting materials have different forms and advantages and disadvantages. Barite powder has a relatively low cost and is widely used in various drilling fluids, but with the increase of solid content, there will be an upper limit for weighting. Ultrafine calcium carbonate has a low cost, but its density is low, and it is difficult to meet the requirements of high-density drilling fluids. Iron ore powder has high density, high hardness and magnetism, which causes serious wear on the drill bit. Compared with other types, micro-manganese ore powder has a smaller particle size, can overcome gravity sedimentation to a great extent, and has better rheological properties, reducing the occurrence of complex situations underground, but its cost is relatively high, and it is generally compounded with other weighting agents. It has received widespread attention in recent years. Weighting materials account for a large proportion of the drilling fluid, and the phenomenon of particle agglomeration of weighting materials often occurs, which will also lead to poor stability of the drilling fluid system, increased plastic viscosity, increased friction resistance, and even drill sticking in severe cases. Dispersants are usually added to modify the surface of the weighting material particles to achieve the effect of suspension stability and reduced apparent viscosity.

[0003] The pH-responsive ionic-nonionic block copolymer dispersant has a decreased hydrophilicity, increased turbidity, and strong surface activity under acidic conditions. As the pH value increases, its hydrophilicity gradually becomes stronger, the turbidity decreases, and the surface activity weakens. At the same time, the ionic and non-ionic regions are separated, the structure is more compact, the functional groups are highly concentrated in the polymer, and the adsorption on the particle surface is more stable. These properties give this type of polymer a wider application prospect.

[0004] Therefore, developing a dispersant with low cost, small dosage and stable suspension effect on weighting materials has important research value for the widespread application of weighting materials in drilling fluids and completion fluids. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a pH-responsive ionic-nonionic block copolymer dispersant and a preparation method and application thereof, which realizes effective separation of functional groups through block means and improves the dispersion effect on micro-manganese home materials.

[0006] The invention adopts reversible addition-fragmentation chain transfer radical polymerization (RAFT), firstly introduces a non-ionic group acrylamide morpholine (ACMO), and then introduces two ionic monomers methacrylic acid (MAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) to obtain a pH-responsive ionic-non-ionic block copolymer, and applies the copolymer to the dispersion of various weighting materials represented by micro-manganese, and has the effect of significantly prolonging the particle suspension time at an extremely low dosage.

[0007] The present invention is achieved through the following technical solutions:

[0008] A pH-responsive ionic-nonionic block copolymer dispersant having a structure shown in the following formula I:

[0009]

[0010] Among them, m=25~100, n=25~100, x=25~200, y=m+n.

[0011] According to a preferred embodiment of the present invention, the ratio of x to y is 1:1 to 8, preferably 1:2.

[0012] Preferably according to the present invention, m=50-100, n=50-100, and x=100-200.

[0013] According to the present invention, the ionic groups methacrylic acid (MAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) structural units are randomly arranged.

[0014] The preparation method of the pH-responsive ionic-nonionic block copolymer dispersant comprises the following steps:

[0015] (1) preparing a mixed solvent, and adding acrylamide morpholine (ACMO) monomer and a RAFT chain transfer agent into the mixed solvent;

[0016] (2) adding an initiator to the system of step (1), stirring until completely dissolved, introducing an inert gas for protection and preheating, keeping the temperature for reaction, and then quenching the reaction with liquid nitrogen to obtain a polymer;

[0017] (3) Adding monomers of methacrylic acid (MAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) to the polymer, and adding a mixed solvent and an initiator, introducing an inert gas again and heating, and quenching the reaction with liquid nitrogen after the reaction, thereby obtaining a pH-responsive ionic-nonionic copolymer dispersant.

[0018] Preferably, in step (1), the mixed solvent is a mixture of two or more of deionized water, 1,4-dioxane, tetrahydrofuran or toluene.

[0019] More preferably, the mixed solvent is a mixture of deionized water and 1,4-dioxane, and the volume ratio of deionized water to 1,4-dioxane is 5 to 10:1. More preferably, the volume ratio of deionized water to 1,4-dioxane is 9:1.

[0020] Preferably, according to the present invention, in step (1), the mass volume ratio of the monomer acryloylmorpholine (ACMO) to the mixed solvent is 0.1 to 2.0:1, g / mL.

[0021] Preferably, according to the present invention, in step (1), the structure of the RAFT chain transfer agent is shown in the following formula II:

[0022]

[0023] Preferably according to the present invention, in step (1), the mass ratio of the RAFT chain transfer agent to acryloylmorpholine is 15 to 120:1.

[0024] Preferably according to the present invention, in step (2), the initiator is azobisisobutyronitrile or 2,2'-azo[2-(2-imidazolin-2-yl)propane] dihydrochloride or 2,2'-azobis(2-methylpropylamidine) dihydrochloride.

[0025] More preferably, the initiator is 2,2'-azo[2-(2-imidazolin-2-yl)propane] dihydrochloride.

[0026] Preferably, according to the present invention, in step (2), the amount of the initiator used is 0.1 to 1.5% of the molar amount of RAFT chain transfer.

[0027] More preferably, the amount of the initiator used is 1.0% of the molar amount of the RAFT chain transfer agent.

[0028] Preferably according to the present invention, in step (2), the inert gas is nitrogen or argon, the preheating temperature is 50 to 110° C., and the reaction time is 5 to 360 min.

[0029] More preferably, the preheating temperature is 100° C. and the reaction time is 10 min.

[0030] According to the preferred embodiment of the present invention, the structure of the obtained polymer is shown in the following formula III:

[0031]

[0032] Among them, x=25~200.

[0033] Preferably according to the present invention, in step (3), the molar ratio of the monomers methacrylic acid (MAA) to 2-acrylamido-2-methylpropanesulfonic acid (AMPS) is 1 to 4:1.

[0034] Preferably, according to the present invention, in step (3), the volume ratio of the total mass of monomers methacrylic acid (MAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) to the added mixed solvent is 0.5 to 2.0:1, g / mL.

[0035] Preferably, according to the present invention, in step (3), the molar amount of the additional initiator is 0.1 to 1.5% of the molar amount of the polymer.

[0036] More preferably, the molar amount of the additional initiator is 1.0% of the molar amount of the polymer.

[0037] Preferably, according to the present invention, in step (3), the inert gas is nitrogen or argon, the reaction temperature is 60-110° C., and the reaction time is 5 to 360 min.

[0038] More preferably, the reaction temperature is 90° C. and the reaction time is 10 min.

[0039] Preferably, according to the present invention, in step (3), the post-treatment method of the finally obtained reaction solution can be based on the existing technology.

[0040] Preferably, in step (3), after the reaction is quenched, post-treatment is performed, and the post-treatment is specifically as follows: the obtained reaction mixture is placed in a dialysis bag, and then dialyzed in water at room temperature for 2 to 4 days, and the liquid in the dialysis bag is freeze-dried to obtain a pH-responsive ionic-nonionic block copolymer dispersant, and the cut-off molecular weight of the dialysis bag is 5000Da.

[0041] The synthesis route of the pH-responsive ionic-nonionic block copolymer dispersant of the present invention is as follows:

[0042]

[0043] The application of the pH-responsive ionic-nonionic block copolymer dispersant as a dispersant for weighting materials in drilling fluid and completion fluid, with an addition amount of 0.01-0.40 wt%, can significantly prolong the suspension time of the weighting materials.

[0044] The technical features and beneficial effects of the present invention are as follows:

[0045] 1. The present invention adopts RAFT method to obtain block copolymers with separated ionic and non-ionic regions. During the whole polymerization process, the free radical activity, structure, molecular weight and molecular weight distribution range are controllable.

[0046] 2. The monomer methacrylic acid used in the present invention can provide an anchoring group, which has better temperature resistance than acrylic acid monomers. 2-Acrylamido-2-methylpropanesulfonic acid has a sulfonic acid group, which is one of the anchoring groups of the weighting material, has good temperature resistance, and has a longer side chain, which helps to provide steric hindrance. Acryloylmorpholine has good amphiphilicity, and the rigid ring structure enables the polymer to have better temperature resistance. The carboxylic acid group contained in the methacrylic acid in the ionic region is sensitive to pH response and shows strong hydrophobicity under acidic conditions. The amphiphilic acryloylmorpholine in the non-ionic region is combined to control the turbidity and amphiphilicity of the polymer by adjusting the pH value.

[0047] 3. The present invention concentrates the ionic groups on one side, and the carboxylic acid groups and sulfonic acid groups in the ionic region are anchoring groups for the weighted material, so that the polymer of the present invention can be more stably adsorbed on the particle surface. The special preparation method obtains a specific structure, combines a specific monomer, and controls the molecular weight within a certain range, so that each group works together to achieve the excellent effect of low dosage and long particle suspension time. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is an infrared spectrum of the pH-responsive ionic-nonionic block copolymer dispersant prepared in Example 1 of the present invention;

[0049] Figure 2 The pH-responsive ionic-nonionic block copolymer dispersant prepared in Example 1 of the present invention is 1 H NMR spectrum;

[0050] Figure 3 The stability analysis PDI diagram of Example 1 of the present invention and the blank control group of micro-manganese weighted material, a is the blank group, and b is Example 1.

[0051] Figure 4 Figure a is an optical microscope picture of a blank control group of micro-manganese weighted material, and figure b is an optical microscope picture of a micro-manganese weighted material after adding Example 1 of the present invention. DETAILED DESCRIPTION

[0052] The present invention can be better understood according to the following examples. However, it is easy for those skilled in the art to understand that the contents described in the examples are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0053] Example 1

[0054] The preparation method of pH responsive ionic-nonionic block copolymer dispersant comprises the following steps:

[0055] (1) In a 5 mL reaction bottle, 0.45 mL of deionized water, 0.05 mL of 1,4-dioxane, 0.5 g of monomer acryloylmorpholine and RAFT chain transfer agent B (0.0333 g, 0.140 mmol) were added in sequence and stirred until completely dissolved. When the solution turned transparent and light yellow, initiator C (0.0023 g, 0.0070 mmol) was added. The mixture was evacuated and filled with argon three times under stirring. The mixture was placed in a module preheated at 100 ° C. and stirred for 10 min. The mixture was then quickly transferred to liquid nitrogen to quench the reaction and allowed to cool.

[0056] (2) Add 0.0753 g of methacrylic acid, 0.1811 g of 2-acrylamido-2-methylpropanesulfonic acid, 0.225 mL of deionized water, 0.025 mL of 1,4-dioxane, and an initiator (0.0005 g, 0.0015 mmol) to the reaction bottle again, stir until completely dissolved, evacuate and fill with nitrogen three times, transfer to a heating module at 90° C., react for 10 min under rapid stirring, then quickly transfer to liquid nitrogen to quench the reaction, and let stand to cool.

[0057] Example 2

[0058] The same preparation method as described in Example 1, except that:

[0059] In step (2), 0.1505 g of methacrylic acid, 0.3623 g of 2-acrylamido-2-methylpropanesulfonic acid, 0.45 mL of deionized water, and 0.05 mL of 1,4-dioxane were added; the other steps and conditions were the same as those in Example 1.

[0060] Example 3

[0061] The same preparation method as described in Example 1, except that:

[0062] In step (2), 0.2258 g of methacrylic acid, 0.5434 g of 2-acrylamido-2-methylpropanesulfonic acid, 0.70 mL of deionized water, and 0.08 mL of 1,4-dioxane were added; the other steps and conditions were the same as those in Example 1.

[0063] Example 4

[0064] The same preparation method as described in Example 1, except that:

[0065] In step (2), 0.3013 g of methacrylic acid, 0.1811 g of 2-acrylamido-2-methylpropanesulfonic acid, 0.45 mL of deionized water, and 0.05 mL of 1,4-dioxane were added; the other steps and conditions were the same as those in Example 1.

[0066] Example 5

[0067] The same preparation method as described in Example 1, except that:

[0068] In step (2), 0.3623 g of 2-acrylamido-2-methylpropanesulfonic acid, 0.60 mL of deionized water, and 0.07 mL of 1,4-dioxane were added; other steps and conditions were consistent with those in Example 3.

[0069] Example 6

[0070] The same preparation method as described in Example 1, except that:

[0071] In step (2), 0.5434 g of 2-acrylamido-2-methylpropanesulfonic acid, 0.76 mL of deionized water, and 0.09 mL of 1,4-dioxane were added; other steps and conditions were consistent with those in Example 3.

[0072] Example 7

[0073] The same preparation method as described in Example 1, except that:

[0074] In step (2), 0.7245 g of 2-acrylamido-2-methylpropanesulfonic acid, 0.90 mL of deionized water, and 0.10 mL of 1,4-dioxane were added; the other steps and conditions were the same as those in Example 3.

[0075] Example 8

[0076] The same preparation method as described in Example 1, except that:

[0077] In step (1), 0.0167 g (0.070 mmol) of RAFT chain transfer agent and 0.0011 g (0.0034 mmol) of initiator were added. In step (2), 0.0003 g (0.0010 mmol) of initiator were added. The other steps and conditions were the same as those in Example 1.

[0078] Example 9

[0079] The same preparation method as described in Example 1, except that:

[0080] In step (1), 0.0083 g (0.035 mmol) of RAFT chain transfer agent and 0.0006 g (0.0019 mmol) of initiator were added. In step (2), 0.0002 g (0.0006 mmol) of initiator were added. The other steps and conditions were the same as those in Example 1.

[0081] Example 10

[0082] The same preparation method as described in Example 1, except that:

[0083] In step (1), 0.0043 g (0.018 mmol) of RAFT chain transfer agent and 0.0003 g (0.0010 mmol) of initiator were added. In step (2), 0.0001 g (0.0003 mmol) of initiator was added. The other steps and conditions were the same as those in Example 1.

[0084] Experimental Example 1

[0085] 1. The infrared spectrum of the pH-responsive ionic-nonionic block copolymer dispersant prepared in Example 1 is shown in Figure 1 , 1 H NMR spectrum Figure 2 , indicating that the present invention successfully prepared the pH-responsive ionic-nonionic block copolymer dispersant.

[0086] 2. In deionized water containing 20 wt% micro-manganese, 0.06 wt% of the pH-responsive ionic-nonionic block copolymer dispersant of Example 1 was added, and no dispersant was used as a blank control. The stability analysis PDI graph is shown in FIG. Figure 3 , indicating that the dispersant of the present invention can well maintain the stability of the system.

[0087] 3. In deionized water containing 0.5wt% micro-manganese, 0.06wt% of pH-responsive ionic-nonionic block copolymer dispersant was added, and no dispersant was used as a blank control. The optical microscope image shows Figure 4 ,pass Figure 4 It can be seen that compared with the blank group, the particle size was significantly reduced after adding the dispersant, which improved the suspension performance of the suspension.

[0088] Experimental Example 2 Performance Testing

[0089] 1. Static sedimentation observation: 0.2 wt % of the pH-responsive ionic-nonionic block copolymer dispersant prepared in Example 1-8 was added to deionized water containing 20 wt % micro-manganese. At the same time, no dispersant was used as a blank control. The static sedimentation was observed in a 10 ml measuring cylinder. According to formula (1), the suspension effect was obtained. The test results are shown in Table 1 below.

[0090]

[0091] Table 1 Suspension properties of pH-responsive ionic-nonionic block copolymer dispersants

[0092]

[0093]

[0094] As can be seen from Table 1, the pH-responsive ionic-nonionic block copolymer dispersants of Examples 1-8 have a very obvious suspension effect on micro-manganese particles, among which Example 3 has the best effect, and after 24 hours, the suspension efficiency remains at 90%. Compared with the blank group experiment, the suspension rate is only 36% after 10 minutes and 22% after 24 hours. This shows that the dispersant of the present invention can be stably adsorbed on the surface of micro-manganese particles for a long time, providing a stable double-electron layer structure and sufficiently strong steric hindrance, so that the micro-manganese particles are less affected by gravity, prolonging the suspension time of the micro-manganese particles, and maintaining the stability of the suspension system.

[0095] 2. Turbidity test: To observe the pH response performance, a 1000 mg / L pH-responsive ionic-nonionic block copolymer dispersant solution was prepared using the dispersant of Example 4. The dispersant solution was adjusted to different pH values ​​using 1.0 mol / L and 0.2 mol / L hydrochloric acid solutions and 1.0 mol / L and 0.2 mol / L sodium hydroxide solutions. The turbidity change was observed using a turbidity meter. The turbidity at different pH values ​​is shown in Table 2.

[0096] Table 2 pH responsiveness of pH responsive ionic-nonionic block copolymer dispersants

[0097]

[0098]

[0099] As can be seen from Table 2, the pH-responsive ionic-nonionic block copolymer dispersant prepared in the embodiment of the present invention is extremely sensitive when the pH is 1-5, and the turbidity changes greatly. At about 6-8, the carboxylic acid is gradually neutralized to sodium carboxylate, showing good hydrophilicity. When sodium hydroxide is continuously added, the carboxylic acid group is completely neutralized, and the turbidity tends to be stable and no longer changes significantly.

[0100] 3. Changes in the particle size of micro-manganese. In deionized water containing 0.5 wt% micro-manganese, 0.06 wt% of a pH-responsive ionic-nonionic block copolymer dispersant was added. At the same time, a blank control was taken without adding a dispersant. The particle size of micro-manganese was tested using a nanoparticle size potentiometer. The dispersion effect of the dispersant on the micro-manganese particles can be determined by the change in the particle size of micro-manganese. The experimental results are shown in Table 3 below.

[0101] Table 3 Changes in particle size of micro manganese particles

[0102]

[0103] The macroscopic performance of the good dispersion of the micro-manganese weighting material is a stable and long suspension time, and the microscopic performance is that the micro-manganese particles maintain a sufficient spacing. The pH-responsive ionic-nonionic block copolymer dispersant allows the micro-manganese particles to have a sufficiently strong electrostatic effect and steric hindrance, so that the micro-manganese weighting material is dispersed in the solution in the form of separate particles, the agglomeration phenomenon is reduced, and the average particle size of the micro-manganese is reduced, thereby verifying the excellent effect of the dispersant. As can be seen from Table 3, the pH-responsive ionic-nonionic block copolymer dispersant has a significant improvement on the particle size of the micro-manganese. The particle size of the blank group without adding the dispersant is 1029nm. After adding, the particle size of the micro-manganese is reduced to below 830nm, and the particle size of Example 3 is reduced to 701nm, indicating that the dispersion degree of the micro-manganese particles is the largest, and the suspension also causes the suspension to have the best suspension performance.

[0104] The above examples are preferred implementations of the present invention, but the implementations of the present invention are not limited to the above examples. Any other substitutions, modifications, combinations, changes, simplifications, etc. that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A pH-responsive ionic-nonionic block copolymer dispersant having a structure as shown in the following formula I: in, m=25-100, n=25-100, x=25-200, y=m+n, and the ratio of x to y is 1:1-8.

2. The pH-responsive ionic-nonionic block copolymer dispersant according to claim 1, characterized in that: m=50-100, n=50-100, x=100-200, the ratio of x to y is 1:2, and the ionic group methacrylic acid (MAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) structural units are randomly arranged.

3. The method for preparing the pH-responsive ionic-nonionic block copolymer dispersant according to claim 1, comprising the following steps: (1) preparing a mixed solvent, and adding acrylamide morpholine (ACMO) monomer and a RAFT chain transfer agent into the mixed solvent; (2) adding an initiator to the system of step (1), stirring until completely dissolved, introducing an inert gas for protection and preheating, keeping the temperature for reaction, and then quenching the reaction with liquid nitrogen to obtain a polymer; (3) Adding monomers of methacrylic acid (MAA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) to the polymer, and adding a mixed solvent and an initiator, introducing an inert gas again and heating, and quenching the reaction with liquid nitrogen after the reaction, thereby obtaining a pH-responsive ionic-nonionic copolymer dispersant.

4. The preparation method according to claim 3, characterized in that: In step (1), the mixed solvent is a mixture of two or more of deionized water, 1,4-dioxane, tetrahydrofuran or toluene.

5. The preparation method according to claim 3, characterized in that: The mixed solvent is a mixture of deionized water and 1,4-dioxane, and the volume ratio of deionized water to 1,4-dioxane is 5 to 10:

1.

6. The preparation method according to claim 3, characterized in that: In step (1), the mass volume ratio of monomer acryloyl morpholine (ACMO) to the mixed solvent is 0.1 to 2.0:1, g / mL, and the structure of the RAFT chain transfer agent is shown in the following formula II: The mass ratio of the RAFT chain transfer agent to acryloylmorpholine is 15 to 120:

1.

7. The preparation method according to claim 3, characterized in that: In step (2), the initiator is azobisisobutyronitrile or 2,2'-azo[2-(2-imidazoline-2-yl)propane] dihydrochloride or 2,2'-azobis(2-methylpropylamidine) dihydrochloride, the amount of the initiator is 0.1-1.5% of the RAFT chain transfer molar amount, the inert gas is nitrogen or argon, the preheating temperature is 50-110° C., and the reaction time is 5-360 min.

8. The preparation method according to claim 3, characterized in that: In step (3), the molar ratio of monomer methacrylic acid (MAA) to 2-acrylamide-2-methylpropanesulfonic acid (AMPS) is 1-4:1, the volume ratio of the total mass of monomer methacrylic acid (MAA) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) to the added mixed solvent is 0.5-2.0:1, g / mL, the molar amount of the added initiator is 0.1-1.5% of the molar amount of the polymer, the inert gas is nitrogen or argon, the reaction temperature is 60-110° C., and the reaction time is 5-360 min.

9. The preparation method according to claim 3, characterized in that: After the reaction is quenched, post-treatment is performed. Specifically, the reaction mixture is placed in a dialysis bag, and then dialyzed in water at room temperature for 2 to 4 days. The liquid in the dialysis bag is freeze-dried to obtain a pH-responsive ionic-nonionic block copolymer dispersant. The molecular weight cutoff of the dialysis bag is 5000Da.

10. Use of the pH-responsive ionic-nonionic block copolymer dispersant of claim 1 as a dispersant for weighting materials in drilling fluids and completion fluids, with an addition amount of 0.01 to 0.40 wt%.

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