Salt-resistant and high-temperature-resistant polymer micro-manganese dispersing agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of water-soluble polymer synthesis and drilling fluid application, and relates to a salt-resistant and high-temperature-resistant polymer micro-manganese dispersing agent as well as a preparation method and application thereof. The invention relates to a preparation method of a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant. The preparation method comprises the following steps: dissolving a carboxylic acid-containing monomer and a sulfonic acid-containing monomer in deionized water; dropwise adding a first functional monomer and a second functional monomer, and then adjusting the pH to be neutral to obtain a mixed solution; introducing nitrogen and heating, adding an initiator aqueous solution after the mixed solution is heated to a preset temperature, and obtaining a polymer solution after the reaction is finished; and dropwise adding the polymer solution into a mixed solution of ethanol and acetone, and filtering to obtain the salt-resistant and high-temperature-resistant polymer micro-manganese dispersing agent. The salt-resistant and high-temperature-resistant polymer micro-manganese dispersing agent is small in dosage and good in effect, when 40% potassium formate water and the micro-manganese content are 36%, only 0.2 wt% of the dispersing agent is used, hot rolling can be conducted for 16 h at the temperature of 210 DEG C, and the viscosity reduction effect is kept to be 40% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of water-soluble polymer synthesis and drilling fluid application, and specifically relates to a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant and a preparation method and application thereof. Background Art

[0002] With the continuous progress of oil production and the continuous development of ultra-deep wells, the completion fluid must have good rheology and good sedimentation stability, and must meet the requirements of environmental protection. At present, the main weighting agents are barite, iron ore powder and limestone, but in high-density drilling fluids, these weighting materials are easy to aggregate and settle, the drilling friction is large, and even the drill is stuck. In order to cope with the above situation, high-density drilling fluids often use micro-manganese as a weighting agent. Micro-manganese is a spherical particle with non-magnetic, high hardness and large specific surface area. The micro-manganese weighting agent has a high specific surface area and good suspension stability, which can significantly reduce the plastic viscosity and low shear rate viscosity of the drilling fluid. At present, there is no easy-to-prepare and excellent micro-manganese dispersant on the market. In order to ensure that the micro-manganese particles can be stably suspended for a long time, a suitable micro-manganese dispersant is of great significance.

[0003] The Chinese invention patent with publication number CN86102915A discloses an acrylic acid copolymer as a dispersant for water-containing slurry, which is applied to drilling fluid. The copolymer is mainly a copolymer of acrylic acid and allyl sulfonate, and can be applied at 150 °C and still has a viscosity reduction effect. The Chinese invention patent with publication number CN103045185A discloses a high-density drilling fluid dispersant. The dispersant is used for barite. After aging at 120 °C for 16 h in a high-temperature furnace, the rheological properties of the base slurry at Φ300 at 60 °C are reduced by 41% compared with the slurry with 1.5% dispersant added.

[0004] The Chinese invention patent with publication number CN111171232A discloses a calcium-resistant zwitterionic polymer suitable for water-based drilling fluids. The molecular weight of the polymer is between 350,000 and 690,000, and the polymer can maintain good hydration and dispersion of the drilling fluid in a high-calcium environment.

[0005] In summary, there is currently no dispersant in the art that can withstand high temperatures above 200 °C and is salt-resistant, and there is no dispersant for micro-manganese weighting materials that can be applied to drilling fluids. Summary of the invention

[0006] In view of the defects of the prior art, the present invention provides a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant and a preparation method and application thereof.

[0007] Specifically, the present invention is achieved through the following technical solutions: A method for preparing a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant comprises: (1) dissolving a carboxylic acid-containing monomer and a sulfonic acid-containing monomer in deionized water; (2) adding the first functional monomer and the second functional monomer dropwise, and then adjusting the pH to neutral to obtain a mixed solution; (3) introducing nitrogen gas and heating, and when the mixed solution reaches a predetermined temperature, adding an initiator aqueous solution, and obtaining a polymer solution after the reaction is completed; (4) The polymer solution is added dropwise into a mixed solution of ethanol and acetone, and filtered to obtain a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant.

[0008] In the preparation method of the above-mentioned salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, the carboxylic acid-containing monomer includes one or two of acrylic acid, methacrylic acid, maleic anhydride or itaconic acid.

[0009] In the preparation method of the above-mentioned salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, the sulfonic acid-containing monomer includes one or two of sodium p-styrene sulfonate, 2-acrylamido-2-methylpropane sulfonic acid, sodium vinyl sulfonate, and sodium allyl sulfonate.

[0010] In the preparation method of the above-mentioned salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, the mass ratio of the carboxylic acid-containing monomer to the sulfonic acid-containing monomer is 1:1 to 20:1.

[0011] In the preparation method of the above-mentioned salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, the first functional monomer is N-vinyl pyrrolidone or 4-acryloylmorpholine.

[0012] In the preparation method of the above-mentioned salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, the second functional monomer is isopentanol polyoxyethylene ether or methyl allyl polyoxyethylene ether.

[0013] In the preparation method of the above-mentioned salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, the mass ratio of the first functional monomer to the second functional monomer is 10:1 to 20:1.

[0014] In the preparation method of the above-mentioned salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, the ratio of the mass of the carboxylic acid-containing monomer to the total mass of the first functional monomer and the second functional monomer is 1:1 to 40:1.

[0015] In the preparation method of the above-mentioned salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, the initiator includes one or more of ammonium persulfate, potassium persulfate, and azobisisobutyramidine hydrochloride.

[0016] In the above-mentioned method for preparing the salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, the amount of the initiator used is 0.5% to 5.0% of the total mass of the monomers.

[0017] In the preparation method of the above-mentioned salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, the nitrogen is introduced for 0.5 to 8 hours, the predetermined temperature is 30°C to 95°C, and the reaction time is 2 to 8 hours.

[0018] On the other hand, the present invention provides a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, which is prepared by the above-mentioned preparation method.

[0019] The above-mentioned salt-resistant and high-temperature-resistant polymer micro-manganese dispersant has a solid content of 10 wt%~50 wt% and a relative molecular weight of 1000~200000.

[0020] In another aspect, the present invention provides a use of a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant in drilling fluid.

[0021] The technical solution of the present invention has the following beneficial effects: (1) The salt-resistant and high-temperature-resistant polymer micro-manganese dispersant of the present invention is suitable for new micro-manganese materials, has a strong adsorption capacity for micro-manganese particles, can provide a sufficiently strong electrostatic effect to keep the micro-manganese suspension stable, and has a viscosity reduction rate of more than 80% for the micro-manganese suspension in clear water; (2) The salt-resistant and high-temperature-resistant polymer micro-manganese dispersant of the present invention has extremely strong heat and salt resistance, with a maximum tolerance temperature of up to 260°C, and still has an extremely excellent dispersion effect in 50% potassium formate brine; (3) The salt-resistant and high-temperature-resistant polymer micro-manganese dispersant of the present invention has a small dosage and a good effect. In 40% potassium formate brine with a micro-manganese content of 36%, only 0.2 wt% of the dispersant of the present invention can be hot-rolled at 210 °C for 16 h, and the viscosity reduction effect is maintained at more than 40%. DETAILED DESCRIPTION

[0022] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific embodiments. Except for the following contents, the process method of the present invention adopts conventional methods or devices in the art. Unless otherwise specified, the following terms have the meanings commonly understood by those skilled in the art.

[0023] The terms "first", "second", etc. used herein do not indicate any order or importance, but are used to distinguish one element from another. When a numerical range is disclosed herein, the above range is considered continuous and includes the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges included therein.

[0024] Specifically, the present invention provides a method for preparing a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, comprising: (1) dissolving a carboxylic acid-containing monomer and a sulfonic acid-containing monomer in deionized water; (2) adding the first functional monomer and the second functional monomer dropwise, and then adjusting the pH to neutral to obtain a mixed solution; (3) introducing nitrogen gas and heating, and when the mixed solution reaches a predetermined temperature, adding an initiator aqueous solution, and obtaining a polymer solution after the reaction is completed; (4) The polymer solution is added dropwise into a mixed solution of ethanol and acetone, and filtered to obtain a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant.

[0025] It can be seen from the above preparation method that the salt-resistant and high-temperature-resistant polymer micro-manganese dispersant of the present invention is prepared by polymerization reaction of a carboxylic acid-containing monomer, a sulfonic acid-containing monomer, a first functional monomer and a second functional monomer.

[0026] The carboxylic acid-containing monomers allow the final polymer to contain a large number of carboxyl groups, which can interact with the surface of micro-manganese particles, thereby reducing the aggregation between micro-manganese particles.

[0027] In some preferred embodiments, the carboxylic acid-containing monomer includes one or two of acrylic acid, methacrylic acid, maleic anhydride or itaconic acid.

[0028] The sulfonic acid-containing monomer allows the final polymer to contain sulfonic acid groups, which can effectively improve the salt resistance of the polymer.

[0029] In some preferred embodiments, the sulfonic acid-containing monomer includes one or two of sodium p-styrene sulfonate, 2-acrylamido-2-methylpropane sulfonic acid, sodium vinyl sulfonate, and sodium allyl sulfonate.

[0030] In some preferred embodiments, the mass ratio of the carboxylic acid-containing monomer to the sulfonic acid-containing monomer is 1:1 to 20:1.

[0031] When the mass ratio of carboxylic acid monomer to sulfonic acid monomer is less than 1:1, the salt resistance of the polymer is enhanced but the dispersibility is deteriorated; when the mass ratio of carboxylic acid monomer to sulfonic acid monomer is greater than 20:1, the dispersibility of the polymer is enhanced but the salt resistance is deteriorated.

[0032] More preferably, the mass ratio of the carboxylic acid-containing monomer to the sulfonic acid-containing monomer is 5:1 to 15:1.

[0033] The addition of functional monomers can effectively improve the temperature resistance of polymers.

[0034] In some preferred embodiments, the functional monomers are divided into first functional monomers and second functional monomers.

[0035] More preferably, the first functional monomer is N-vinyl pyrrolidone or 4-acryloylmorpholine.

[0036] More preferably, the second functional monomer is isopentanol polyoxyethylene ether or methyl allyl polyoxyethylene ether.

[0037] More preferably, the mass ratio of the first functional monomer to the second functional monomer is 10:1 to 30:1.

[0038] In some preferred embodiments, the mass ratio of the carboxylic acid-containing monomer to the functional monomer is 1:1 to 40:1.

[0039] When the mass ratio of the carboxylic acid monomer to the functional monomer is less than 1:1, the temperature resistance of the polymer is enhanced but the dispersibility is deteriorated; when the mass ratio of the carboxylic acid monomer to the functional monomer is greater than 40:1, the dispersibility of the polymer is enhanced but the temperature resistance is deteriorated.

[0040] More preferably, the mass ratio of the carboxylic acid-containing monomer to the functional monomer is 10:1 to 30:1.

[0041] The initiator generates free radicals at a certain temperature to initiate the entire reaction and finally form the target polymer.

[0042] In some preferred embodiments, the initiator includes one or more of ammonium persulfate, potassium persulfate, and azobisisobutyramidine hydrochloride.

[0043] In some preferred embodiments, the mass of the initiator accounts for 0.5% to 5.0% of the total weight of the monomers, and more preferably 1.0% to 4.0%.

[0044] In some preferred embodiments, the nitrogen is introduced for 0.5 to 8 h, the predetermined temperature is 30° C. to 95° C., and the reaction time is 2 to 8 h.

[0045] On the other hand, the present invention also provides a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant prepared according to the method of the present invention, with a solid content (ie, the mass ratio of all monomers to the dispersant) of 10 wt% to 50 wt% and a relative molecular weight of 1000 to 200000.

[0046] In another aspect, the present invention also provides the use of the salt-resistant and high-temperature-resistant polymer micro-manganese dispersant in drilling fluid.

[0047] Preferably, the specific application method is as follows: prepare a micro-manganese potassium formate solution, stir it evenly at a high speed, add a dispersant accounting for 0.1 wt%~1.5 wt% of the total mass, stir it at a high speed, and then put it into a high-temperature rolling furnace or aging furnace.

[0048] The salt-resistant and high-temperature-resistant polymer micro-manganese dispersant of the present invention has a strong adsorption effect on micro-manganese particles, can provide a stable and strong electrostatic effect, can keep a large number of micro-manganese particles suspended and stable under the condition of a small amount, has an obvious viscosity reduction effect on drilling fluid, and can ensure a long-term stable sedimentation factor. Its salt resistance performance is extremely excellent, and the impact in potassium formate brine is very small. It is effective for a long time at a high temperature of 210°C, and the maximum tolerable temperature can reach 260°C. It is suitable for a high-temperature, high-mineralization, high-density drilling and completion fluid system.

[0049] Example The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions. The raw materials used in the following examples are all conventionally purchased.

[0050] Example 1 Add 15 g acrylic acid to the flask, add 16.5 mL of deionized water, stir until completely dissolved, add 3 g of sodium vinyl sulfonate, stir and ultrasonic until completely dissolved, add 1.5 g of N-vinyl pyrrolidone and 0.08 g of methyl allyl polyoxyethylene ether, add 0.55 g of NaOH, adjust the pH to neutral, heat the water bath to 50 °C, pass nitrogen below the liquid surface, and keep the liquid surface bubbling at a rate of 10 mL / min. Take another 0.6 g of ammonium persulfate, add 3 ml of deionized water until completely dissolved, slowly drop it into the three-necked flask, react for 3 h, cool it, slowly drop it into a mixed solution of ethanol and acetone (mass ratio 1:1), precipitate a white or light yellow powder, and dry it to constant weight to obtain a salt-resistant and high-temperature resistant polymer micro-manganese dispersant PMN1.

[0051] Example 2 Add 12 g of itaconic acid to the flask, add 13.5 mL of deionized water, stir until completely dissolved, add 3 g of sodium vinyl sulfonate, stir and ultrasonic until completely dissolved, add 1.5 g of N-vinyl pyrrolidone and 0.08 g of isopentanol polyoxyethylene ether, add 0.55 g of NaOH, adjust the pH to neutral, heat the water bath to 50 °C, pass nitrogen below the liquid surface, and keep the liquid surface bubbling at a rate of 10 mL / min. Take another 0.5 g of potassium persulfate, add 3 mL of deionized water until completely dissolved, slowly drop it into the three-necked flask, react for 3 h, cool it, slowly drop it into a mixed solution of ethanol and acetone (mass ratio 1:1), precipitate a white or light yellow powder, and dry it to constant weight to obtain a salt-resistant and high-temperature resistant polymer micro-manganese dispersant PMN2.

[0052] Example 3 Add 12 g of sodium methacrylate to the flask, add 16.5 mL of deionized water, stir until completely dissolved, add 6 g of sodium vinyl sulfonate, stir and ultrasonic until completely dissolved, 1.5 g of N-vinyl pyrrolidone and 0.08 g of isopentanol polyoxyethylene ether, add 1.0 g of NaOH, adjust the pH to neutral, heat the water bath to 50 °C, pass nitrogen below the liquid surface, and keep the liquid surface bubbling at a rate of 10 mL / min. Take another 0.6 g of potassium persulfate, add 3 mL of deionized water until completely dissolved, slowly drop it into the three-necked flask, react for 3 h, cool it, slowly drop it into a mixed solution of ethanol and acetone (mass ratio 1:1), precipitate a white or light yellow powder, and dry it to constant weight to obtain a salt-resistant and high-temperature resistant polymer micro-manganese dispersant PMN3.

[0053] Example 4 Add 12 g acrylic acid to the flask, add 11.25 mL of deionized water, stir until completely dissolved, add 1.5 g sodium p-styrene sulfonate, stir and ultrasonic until completely dissolved, add 0.75 g N-vinyl pyrrolidone and 0.08 g isopentanol polyoxyethylene ether, add 0.3 g NaOH, adjust the pH to neutral, heat the water bath to 50 °C, pass nitrogen below the liquid surface, and keep the liquid surface bubbling at a rate of 10 mL / min. Take another 0.4 g potassium persulfate, add 3 mL of deionized water until completely dissolved, slowly drop it into the three-necked flask, react for 3 h, cool it, slowly drop it into a mixed solution of ethanol and acetone (mass ratio 1:1), precipitate a white or light yellow powder, and dry it to constant weight to obtain a salt-resistant and high-temperature resistant polymer micro-manganese dispersant PMN4.

[0054] Example 5 Add 6 g of sodium methacrylate to the flask, add 7.5 mL of deionized water, stir until completely dissolved, add 3 g of 2-acrylamido-2-methylpropanesulfonic acid, stir and ultrasonic until completely dissolved, add 1.5 g of N-vinyl pyrrolidone and 0.08 g of isopentanol polyoxyethylene ether, add 0.55 g of NaOH, adjust the pH to neutral, heat the water bath to 50 °C, pass nitrogen below the liquid surface, and keep the liquid surface bubbling at a rate of 10 mL / min. Take another 0.3 g of ammonium persulfate, add 3 mL of deionized water until completely dissolved, slowly drop it into the three-necked flask, react for 3 h, cool it, slowly drop it into a mixed solution of ethanol and acetone (mass ratio 1:1), precipitate a white or light yellow powder, and dry it to constant weight to obtain a salt-resistant and high-temperature resistant polymer micro-manganese dispersant PMN5.

[0055] Comparative Example 1 Add 1.5 g of itaconic acid to the flask, add 24 mL of deionized water, stir until completely dissolved, add 24 g of sodium allyl sulfonate, stir and ultrasonic until completely dissolved, add 1.5 g of 4-acryloylmorpholine and 0.08 g of methyl allyl polyoxyethylene ether, add 2.0 g of NaOH, adjust the pH to neutral, heat the water bath to 50 °C, pass nitrogen below the liquid surface, and keep the liquid surface bubbling at a rate of 10 mL / min. Take another 0.8 g of azobisisobutylamidine hydrochloride, add 3 mL of deionized water until completely dissolved, slowly drop it into the three-necked flask, react for 3 h, cool it, slowly drop it into a mixed solution of ethanol and acetone (mass ratio 1:1), precipitate a white or light yellow powder, and dry it to constant weight to obtain a salt-resistant and high-temperature resistant polymer micro-manganese dispersant PMN6.

[0056] Performance testing: 1. Static sedimentation observation: add 0.2 wt% of salt-resistant and high-temperature-resistant polymer micro-manganese dispersant into a 10 mL measuring cylinder in a deionized water solution containing 20% ​​micro-manganese, and observe the sedimentation. According to formula (1), the suspension effect is obtained. The experimental results are shown in Table 1 below.

[0057] (1) Table 1 Effects of salt-resistant and high-temperature-resistant polymer micro-manganese dispersants on the suspension properties of micro-manganese particles

[0058] As can be seen from Table 1, the salt-resistant and high-temperature-resistant polymer micro-manganese dispersant (PMN7) has a slightly poor suspension effect on micro-manganese, among which PMN1 and PMN2 have the best effect. After 60 hours, the suspension efficiency remains at 84%. Compared with the blank control experiment, the dispersant effect is very obvious, which 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 double electron layer structure, so that the micro-manganese particles have a sufficiently strong electrostatic interaction and maintain the stability of the suspension.

[0059] 2. The viscosity reduction effect of some salt-resistant and high-temperature-resistant polymer micro-manganese dispersants was tested. The test results of potassium formate brine are shown in Table 2, and the test results of drilling fluid system are shown in Table 3.

[0060] Table 2 Test method, add a certain amount of potassium formate and micro manganese to deionized water, potassium formate accounts for 40% of the total mass, micro manganese accounts for 35% of the total mass, add 0.2 wt% of salt-resistant and high-temperature resistant polymer micro manganese dispersant, stir at high speed until uniform, and measure the viscosity with a six-speed viscometer at 50°C. Transfer the slurry to an aging tank, heat roll at 210°C for 16 h, take it out and measure the viscosity with a six-speed viscometer at 50°C.

[0061] Table 3 Test method, according to the completion fluid formula, including 41.48 wt% micro manganese weighting agent, 38.78 wt% potassium formate, 18.65 wt% deionized water, 0.01 wt% viscosity enhancer (Blue Ocean Boda Technology Co., Ltd., PF-POLYVIS) and 0.01 wt% salt-resistant and high-temperature resistant polymer micro manganese dispersant, high-speed stirring until uniform, the viscosity is measured at 50 ° C with a six-speed viscometer. The slurry was transferred to an aging tank, hot rolled at 210 ° C for 16 h, and the viscosity was measured at 50 ° C with a six-speed viscometer after being taken out.

[0062] Table 2 Effect of PMN2 on the viscosity of micromanganese particles in potassium formate brine

[0063] Table 3 Effect of PMN2 on viscosity in completion fluid system

[0064] As can be seen from Table 2, after hot rolling, the viscosity of the slurry with the dispersant added was significantly reduced, indicating that PMN2 was not affected at high mineralization and high temperature of 210 °C. Its viscosity reduction rate reached 42% under Φ600 conditions and 50% under Φ300 conditions, showing extremely excellent viscosity reduction performance. It can also be seen from Table 3 that after adding PMN2, the viscosity was significantly reduced compared with the drilling fluid base slurry, so the stability of the completion fluid system can be guaranteed.

[0065] 3. The 3-day sedimentation factors of some salt-resistant and high-temperature-resistant polymer micro-manganese dispersants were tested. The test results are shown in Table 4.

[0066] The test method includes 41.48 wt% micro-manganese weighting agent, 38.78 wt% potassium formate, 18.65 wt% deionized water, 0.01 wt% viscosity enhancer (Blue Ocean Boda Technology Co., Ltd., PF-POLYVIS) and 0.01 wt% salt-resistant and high-temperature resistant polymer micro-manganese dispersant, which are placed in an aging tank at 210 °C and left to stand for 3 days. The densities of the upper and lower layers are measured, and the completion fluid sedimentation factor (SF) is calculated according to formula (2). ρ1 and ρ2 are obtained by dividing the total height of the completion fluid in the aging tank into three sections, taking out the top section of drilling fluid into a constant volume container, weighing it, and calculating the density as ρ1. After removing the second section in the middle, the remaining is the third section at the bottom. The third section of drilling fluid is transferred to a constant volume container, weighed, and the density is calculated as ρ2. (2) Table 4 Effect of salt-resistant and high-temperature-resistant polymer micro-manganese dispersant on drilling fluid sedimentation factor

[0067] As can be seen from Table 4, PMN2 has the best effect, with a sedimentation factor of 0.506, and the other tested PMN1 and PMN3 are also within the safe range (SF=0.50-0.52). This shows that in this completion fluid system, after standing at 210 °C for three days, the densities of the upper and lower layers are basically the same, with no obvious sedimentation, meeting the requirements of the drilling fluid, fully proving the effectiveness and stability of the present invention in dispersing micro-manganese particles, and showing extremely excellent temperature resistance and salt resistance.

[0068] The present invention has been disclosed above with preferred embodiments, but those skilled in the art should understand that these embodiments are only used to describe the present invention and should not be understood as limiting the scope of the present invention. It should be noted that all changes and substitutions equivalent to these embodiments should be deemed to be included in the scope of the claims of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined in the claims.

Claims

1. A method for preparing a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, characterized in that: include: (1) dissolving a carboxylic acid-containing monomer and a sulfonic acid-containing monomer in deionized water; (2) adding the first functional monomer and the second functional monomer dropwise, and then adjusting the pH to neutral to obtain a mixed solution; (3) introducing nitrogen gas and heating, and when the mixed solution reaches a predetermined temperature, adding an initiator aqueous solution, and obtaining a polymer solution after the reaction is completed; (4) The polymer solution is added dropwise into a mixed solution of ethanol and acetone, and filtered to obtain a salt-resistant and high-temperature-resistant polymer micro-manganese dispersant.

2. The preparation method according to claim 1, characterized in that: The carboxylic acid-containing monomer includes one or two of acrylic acid, methacrylic acid, maleic anhydride or itaconic acid.

3. The preparation method according to claim 1, characterized in that: The sulfonic acid-containing monomers include one or two of sodium p-styrene sulfonate, 2-acrylamido-2-methylpropane sulfonic acid, sodium vinyl sulfonate, and sodium allyl sulfonate.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the carboxylic acid-containing monomer to the sulfonic acid-containing monomer is 1:1 to 20:

1.

5. The preparation method according to claim 1, characterized in that: The first functional monomer is N-vinyl pyrrolidone or 4-acryloylmorpholine.

6. The preparation method according to claim 1, characterized in that: The second functional monomer is isopentanol polyoxyethylene ether or methyl allyl polyoxyethylene ether.

7. The preparation method according to claim 1, characterized in that: The mass ratio of the first functional monomer to the second functional monomer is 10:1 to 20:

1.

8. The preparation method according to claim 1, characterized in that: The ratio of the mass of the carboxylic acid-containing monomer to the total mass of the first functional monomer and the second functional monomer is 1:1 to 40:

1.

9. The preparation method according to claim 1, characterized in that: The initiator includes one or more of ammonium persulfate, potassium persulfate, and azobisisobutyramidine hydrochloride.

10. The preparation method according to claim 1, characterized in that: The amount of the initiator used is 0.5% to 5.0% of the total weight of the monomers.

11. The preparation method according to claim 1, characterized in that The nitrogen introduction time is 0.5 to 8 h, the predetermined temperature is 30° C. to 95° C., and the reaction time is 2 to 8 h.

12. A salt-resistant and high-temperature-resistant polymer micro-manganese dispersant, characterized in that: The preparation method is described in any one of claims 1 to 11.

13. The salt-resistant and high-temperature-resistant polymer micro-manganese dispersant according to claim 12, characterized in that: The solid content is 10wt%~50 wt%, and the relative molecular weight is 1000~200000.

14. Use of the salt-resistant and high-temperature-resistant polymer micro-manganese dispersant according to claim 12 or 13 in drilling fluid.

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