A barite dispersant and its preparation method and application

Abstract

The present invention provides a barite dispersant, its preparation method, and application. The barite dispersant comprises, by molar ratio, 60% to 80% carboxyl monomer, 40% to 20% sulfonic acid monomer, and 1% to 3% initiator. One or more carboxyl monomers are polymerized with one or more sulfonic acid monomers to form a polymer dispersant containing both carboxyl and sulfonic acid groups. By adjusting the monomer ratio to maintain a reasonable ratio of sulfonic acid groups to carboxyl groups on the polymer, the barite dispersion rate is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling fluids, and in particular relates to a barite dispersant and a preparation method and application thereof. Background Art

[0002] Barite is an important weighting agent in drilling fluids and is used in large quantities in high-density drilling fluids. 3 In high-density wells, barite usage accounts for approximately 35% of the total well mud cost. In deep, high-density wells, this percentage can reach as high as 50%. Effective barite recycling will significantly reduce drilling costs for high-density wells while also enabling resource reuse.

[0003] Currently, barite recycling mainly utilizes the density difference between barite and clay drill cuttings, and is recovered by centrifugal separation. Because a large amount of viscosity-enhancing and shear-enhancing agents are added to the drilling fluid during the drilling process, they have a coating effect on the solid phase particles in the drilling fluid, causing some clay drill cuttings to be coated with barite. The barite separated by centrifugal separation has a high clay drill cutting content, making it difficult to meet the requirements for recycling. At the same time, the particle size of barite increases after being coated with clay, and secondary processing is required for reuse, which increases the cost of recycling barite. The method of using a large amount of clean water dilution and washing can improve the recovery rate of barite, but it consumes a lot of water and increases the waste liquid phase, and the cost of harmlessness is high.

[0004] To improve the dispersion of barite, some studies have opted to modify the barite's surface to enhance its dispersion. Patents "A Method for Preparing Highly Dispersible Barite" (Application No. 2019108131954) and "A Method for Preparing Highly Dispersible Barite" (Application No. 2020101383976) both add surfactants during the barite production process to enhance its dispersion in organic matter. However, these surfactants alter the barite's hydrophilicity, making it difficult to disperse in water-based mud. Patents "A Method for Preparing a Flotation Collector for Carbon-Containing and Mud-Containing Barite" (Application No. 2013106746533) and "A Method for Preparing a Flotation Collector for Barite" (Application No. 200310106582.3) use collectors that render the barite's surface hydrophobic, allowing it to float. Barite treated with these collectors, because their surface becomes hydrophobic instead of hydrophilic, is not suitable for dispersion in water-based drilling fluids. The present invention is a novel dispersant, which carries a certain proportion of sulfonic acid groups and carboxyl groups on the dispersant. The sulfonic acid groups, as strong acid groups, will be preferentially adsorbed on the barite surface. Due to its stronger polarity, it can seize the adsorption sites of other drilling fluid treatment agents on the barite, so that the barite is desorbed from the package of the drilling fluid treatment agent. Simultaneously, due to the carboxyl groups with a large amount of weak acid on the dispersant, it stretches in water, like a layer of negative charge layer wrapping around the barite. Barite and negatively charged clay cuttings are repelled from each other, effectively reducing the reunion of barite and clay, and improving the dispersibility of barite. The ratio of sulfonic acid groups to carboxyl groups on the dispersant determines the quality of the dispersant dispersion effect. When separating barite by the method for centrifugal separation, the content of clay cuttings in the barite recovery process can be effectively reduced, and the recovered barite grade is improved. Summary of the Invention

[0005] In order to solve the above problems in the prior art, the present invention provides a barite dispersant and a preparation method and application thereof.

[0006] In a first aspect, the present invention provides a barite dispersant, which comprises, by molar ratio, 60% to 80% of a carboxyl monomer, 40% to 20% of a sulfonic acid monomer, and 1% to 3% of an initiator.

[0007] As a specific embodiment of the present invention, the carboxyl monomer includes but is not limited to at least one of acrylic acid and crotonic acid.

[0008] As a specific embodiment of the present invention, the sulfonic acid monomer is at least one of sodium vinyl sulfonate, sodium propylene sulfonate, and 2-acrylamide-2-methylpropane sulfonic acid (AMPS).

[0009] As a specific embodiment of the present invention, the initiator is potassium persulfate or ammonium persulfate.

[0010] In a second aspect, the present invention provides a method for preparing the barite dispersant, comprising the following steps:

[0011] S1: dissolving a carboxyl monomer and a sulfonic acid monomer in water to obtain a carboxyl monomer aqueous solution and a sulfonic acid monomer aqueous solution;

[0012] S2: mixing the carboxyl monomer aqueous solution and the sulfonic acid monomer aqueous solution obtained in step S1, adjusting the pH value, adding an initiator and passing nitrogen gas, and performing a polymerization reaction to obtain a polymer;

[0013] S3: Drying and crushing the polymer obtained in step S2 to obtain the barite dispersant.

[0014] As a specific embodiment of the present invention, in step S1, the carboxyl monomer includes but is not limited to at least one of acrylic acid and crotonic acid; and / or,

[0015] As a specific embodiment of the present invention, the sulfonic acid monomer is at least one of sodium vinyl sulfonate, sodium propylene sulfonate, and 2-acrylamide-2-methylpropanesulfonic acid (AMPS); and / or,

[0016] As a specific embodiment of the present invention, the mass percentage concentrations of the carboxyl monomer aqueous solution and the sulfonic acid monomer aqueous solution are independently 20 to 40%.

[0017] As a specific embodiment of the present invention, in step S2, the volume ratio of the carboxyl monomer aqueous solution to the sulfonic acid monomer aqueous solution is 1: (0.65-1.5); and / or,

[0018] As a specific embodiment of the present invention, the pH value is adjusted to 7-9, and the pH value is adjusted using an alkaline regulator, and the alkaline regulator includes: and / or,

[0019] As a specific embodiment of the present invention, the initiator is potassium persulfate or ammonium persulfate, and the amount of the initiator added is 1% to 3% by mass of the aqueous solution; and / or,

[0020] As a specific embodiment of the present invention, the polymerization reaction conditions include: reaction temperature of 15 to 25° C., stirring rate of 100 to 150 r / min, and reaction time of 2 to 4 h.

[0021] As a specific embodiment of the present invention, in step S3, the viscosity-average molecular weight of the polymer is between 10,000 and 100,000, and the molar ratio of the structural units derived from the carboxylic acid monomer to the structural units derived from the sulfonic acid monomer in the polymer is controlled at (3-2):(1-2).

[0022] In a third aspect, the present invention provides an application of the barite dispersant prepared by the preparation method in the field of recycling and reusing waste high-density drilling fluid barite.

[0023] As a specific embodiment of the present invention, the mass fraction ratio of the barite dispersant in the total amount of the waste high-density drilling fluid is 0.5% to 3%.

[0024] When the barite dispersant of the present invention is used in the drilling process, when performing on-site barite recovery while drilling, 0.5% to 2% of the barite dispersant of the present invention should be added to the total amount of mud for two cycles before starting the low-speed centrifuge for separation. After the barite dispersant of the present invention is fully dissolved and dispersed, the low-speed centrifuge is started to allow the drilling fluid returned from the bottom of the well to first pass through the low-speed centrifuge to recover the barite, and then pass through the high-speed centrifuge to remove the inferior solid phase.

[0025] The barite dispersant of the present invention is used to improve the purity of barite recovery in waste high-density drilling fluid. If a flocculant is used to break the gel in the waste drilling fluid, 0.5% to 1.5% of the barite dispersant should be added to the waste drilling fluid before adding the flocculant, stirring in the mud pool for 1 hour, and then adding the flocculant to break the gel in the system. After the drilling fluid system is broken, 0.5% to 1% of the barite dispersant is added, and stirring in the mud pool for another 1 hour is continued before the subsequent barite recovery process is carried out.

[0026] The barite dispersant of the present invention is used to improve the purity of barite recovery from waste high-density drilling fluid. If the waste drilling fluid is treated by electrocoagulation to break the gel, 0.5% to 2% of the barite dispersant is added to the waste drilling fluid before it enters the electrolytic cell. The fluid is stirred in the mud tank for 1 hour, and then electrocoagulation is performed to break the gel before the subsequent barite recovery process.

[0027] The barite dispersant of the present invention is used to improve the purity of barite recovery from waste high-density drilling fluid. If the waste drilling fluid is treated by adding clean water to the drilling fluid for gel breaking, clean water is added to the waste drilling fluid, and then 0.5% to 1% of the original mud volume of the barite dispersant is added to the mud. The mud is stirred in a mud tank for 1 hour, and then the subsequent barite recovery process is carried out.

[0028] The above raw materials in the present invention can be prepared in-house or purchased commercially, and the present invention is not particularly limited thereto.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The barite dispersant of the present invention has a polymer of sulfonic acid groups and carboxyl groups at the same time. By adjusting the ratio of sulfonic acid groups to carboxyl groups on the polymer, the polymer can be preferentially adsorbed on the surface of barite in the mud, and can effectively reduce the agglomeration of barite and clay, thereby increasing the density of recovered barite, which is conducive to the secondary reuse of barite.

[0031] 2. Compared with the prior art which uses a large amount of clean water to dilute and rinse the mud multiple times, the barite dispersant of the present invention has a dilution ratio of slurry to water of more than 1:10, which can effectively increase the density of recovered barite. However, it consumes a lot of water, produces a large amount of waste mud, and increases the difficulty and cost of harmless treatment of the mud. The use of the barite dispersant of the present invention can achieve the effect of increasing the density of recovered barite without increasing the amount of mud.

[0032] 3. The barite dispersant of the present invention can reduce drilling costs and reduce the cost and difficulty of processing waste mud. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to specific examples, but they do not constitute any limitation to the present invention.

[0034] Example 1

[0035] This embodiment provides a barite dispersant and a preparation method thereof, the specific details of which are as follows:

[0036] S1: Prepare 100 mL of 30% by mass acrylic acid solution;

[0037] Prepare 100 mL of 30% by mass 2-acrylamide-2-methylpropanesulfonic acid (AMPS) solution;

[0038] S2: The acrylic acid solution and 2-acrylamide-2-methylpropanesulfonic acid solution obtained in step S1 were slowly added dropwise to a three-necked flask over 30 minutes, respectively. The pH value was adjusted to 8 with potassium hydroxide, and 0.3 g of potassium persulfate was added. The reaction temperature was controlled at 15°C. Nitrogen was passed through the experiment, and the stirring rate was controlled at 100 rpm. The polymerization reaction was carried out for 2 hours to obtain a polymer.

[0039] S3: Dry and crush the polymer obtained in step S2 to obtain a barite dispersant.

[0040] The barite dispersant obtained in Example 1 has a viscosity-average molecular weight of 40,000 and a particle size between 200 mesh and 300 mesh, wherein the molar ratio of the carboxylic acid monomer to the sulfonic acid monomer is 3:1.

[0041] Example 2

[0042] This embodiment provides a barite dispersant and a preparation method thereof, the specific details of which are as follows:

[0043] S1: 50 mL of 20% by mass acrylic acid solution and 50 mL of 20% by mass crotonic acid solution were prepared to prepare 100 mL of carboxyl monomer solution.

[0044] 50 mL of 40% by mass 2-acrylamide-2-methylpropanesulfonic acid (AMPS) solution and 50 mL of 40% by mass sodium vinyl sulfonate solution were mixed to prepare 100 mL of sulfonic acid monomer solution.

[0045] S2: The carboxyl monomer solution and the sulfonic acid monomer solution obtained in step S1 were slowly added dropwise to a three-necked flask over a period of 15 minutes, respectively. The pH value was adjusted to 7 with potassium hydroxide, 0.3 g of ammonium persulfate was added, the reaction temperature was controlled at 20°C, nitrogen was passed through the experiment, the stirring rate was controlled at 100 r / min, and the polymerization reaction was carried out for 3 hours to obtain a polymer.

[0046] S3: Dry and crush the polymer obtained in step S3 to obtain a barite dispersant.

[0047] The barite dispersant obtained in Example 2 has a viscosity-average molecular weight of 30,000, a particle size between 200 mesh and 300 mesh, and a molar ratio of the carboxylic acid monomer to the sulfonic acid monomer of 1.2:1.

[0048] Example 3

[0049] This embodiment provides a barite dispersant and a preparation method thereof, the specific details of which are as follows:

[0050] S1: 100 mL of 40% crotonic acid solution;

[0051] Prepare 150 mL of sulfonic acid monomer solution by mixing 100 mL of 40% by mass 2-acrylamide-2-methylpropanesulfonic acid (AMPS) solution and 50 mL of 40% by mass sodium propylene sulfonate solution;

[0052] S2: The butenoic acid solution and sulfonic acid monomer solution obtained in step S1 were slowly added dropwise to a three-necked flask over a period of 20 minutes, respectively. The pH value was adjusted to 9 with potassium hydroxide, 0.2 g of potassium persulfate was added, the reaction temperature was controlled at 25°C, nitrogen was passed through the experiment, the stirring rate was controlled at 150 r / min, and the polymerization reaction was carried out for 4 hours to obtain a polymer.

[0053] S3: Dry and crush the polymer obtained in step S3 to obtain a barite dispersant.

[0054] The barite dispersant obtained in Example 3 has a viscosity-average molecular weight of 30,000, a particle size between 200 mesh and 300 mesh, and a molar ratio of the carboxylic acid monomer to the sulfonic acid monomer of 1.4:1.

[0055] Example 4

[0056] This embodiment provides a barite dispersant and a preparation method thereof, the specific details of which are as follows:

[0057] S1: Prepare 130 mL of 27% by mass acrylic acid solution as a carboxylic acid monomer solution;

[0058] Prepare 150 mL of 35% by mass 2-acrylamide-2-methylpropanesulfonic acid (AMPS) solution;

[0059] S2: The carboxyl monomer solution and 2-acrylamide-2-methylpropanesulfonic acid solution obtained in step S1 were slowly added dropwise to a three-necked flask over 30 minutes, respectively. The pH value was adjusted to 8 with potassium hydroxide, and 0.3 g of potassium persulfate was added. The reaction temperature was controlled at 25°C. Nitrogen was passed through the reaction, and the stirring rate was controlled at 150 r / min. The polymerization reaction was carried out for 2.5 hours to obtain a polymer.

[0060] S3: Dry and crush the polymer obtained in step S3 to obtain a barite dispersant.

[0061] The barite dispersant obtained in Example 4 has a viscosity-average molecular weight of 50,000, a particle size between 200 mesh and 300 mesh, and a molar ratio of the carboxylic acid monomer to the sulfonic acid monomer of 2:1.

[0062] Example 5

[0063] This embodiment provides a barite dispersant and a preparation method thereof, the specific details of which are as follows:

[0064] S1: Prepare 150 mL of 20% crotonic acid solution.

[0065] Prepare 150 mL of 30% by mass 2-acrylamide-2-methylpropanesulfonic acid (AMPS) solution;

[0066] S2: The butenoic acid solution and 2-acrylamide-2-methylpropanesulfonic acid solution obtained in step S1 were slowly added dropwise to a three-necked flask over a period of 20 min, respectively. The pH value was adjusted to 9 with potassium hydroxide, 0.1 g of potassium persulfate was added, the reaction temperature was controlled at 23°C, nitrogen was passed through the experiment, the stirring rate was controlled at 150 r / min, and the polymerization reaction was carried out for 2.5 h to obtain a polymer.

[0067] S3: Dry and crush the polymer obtained in step S3 to obtain a barite dispersant.

[0068] The barite dispersant obtained in Example 5 has a viscosity-average molecular weight of 50,000, a particle size between 200 mesh and 300 mesh, and a molar ratio of the carboxylic acid monomer to the sulfonic acid monomer of 1.6:1.

[0069] Application Examples 1-5

[0070] Application Examples 1-5 are examples of the barite dispersants obtained in Examples 1-5 of the present invention, respectively applied in a drilling process of a certain project to perform on-site barite recovery while drilling. The specific details are as follows:

[0071] S1: Before starting the low-speed centrifuge for separation, add 0.5% to 2% of the total drilling fluid barite dispersant for two cycles. The specific addition amount is shown in Table 1. The barite dispersant is added from the mud tank sampling port. The dispersant circulates in the wellbore with the drilling fluid and can be effectively dispersed during the circulation process.

[0072] S2: Turn on the low-speed centrifuge equipped by the well team and let the drilling fluid returned from the bottom of the well pass through the low-speed centrifuge first. The centrifuge speed is controlled at 1500r / min. The barite separated from the bottom flow outlet of the centrifuge is the recovered barite, which can be directly returned to the mud tank for reuse. The low-density drilling fluid flowing out of the overflow port is then passed through a high-speed centrifuge to remove the inferior solid phase.

[0073] Application Examples 6-10

[0074] Application Examples 6-10 are the application of the barite dispersant obtained in Examples 1-5 of the present invention to the waste high-density drilling fluid barite recovery purity of the project. The waste drilling fluid is treated with a flocculant for gel breaking. The specific details are as follows:

[0075] S1: Add the barite dispersant obtained in Examples 1-5 to the waste high-density drilling fluid in two batches, with the amount added each time being 0.5% to 1.5%, for a total of 1% to 3%. First, add 0.5% to 1.5% of the barite dispersant obtained in Examples 1-5 to the waste drilling fluid by weight, and stir in a mud pit for 1 hour at a stirring rate of 3000 r / min. The specific addition amount is shown in Table 1;

[0076] S2: Add flocculant to the drilling fluid to break the gel in the system;

[0077] S3: After the drilling fluid system is degelled, 0.5% to 1% of the barite dispersant obtained in Examples 1-5 is added and stirring is continued in the mud tank for 1 hour at a stirring rate of 3000 r / min. The drilling fluid is then processed using a low-speed centrifuge at a speed of 1500 r / min, and the barite is separated and recovered at the centrifuge underflow.

[0078] Application Examples 11-15

[0079] Application Examples 11-15 are applications of the barite dispersants obtained in Examples 1-5 of the present invention in improving the purity of barite recovery from waste high-density drilling fluid. The waste drilling fluid is treated by electrocoagulation for gel breaking. The details are as follows:

[0080] S1: Add 0.5% to 2% of the barite dispersant obtained in Examples 1-5 to the waste drilling fluid, and stir in a mud pool for 1 hour at a stirring rate of 3000 r / min. The specific addition amount is shown in Table 1.

[0081] S2: The drilling fluid is subjected to electrocoagulation and gel breaking, the gel breaking time is 8 minutes, the plate spacing is 4 cm, and the plate voltage is 4V.

[0082] S3: The drilling fluid after gel breaking is processed by a low-speed centrifuge at a speed of 1500r / min, and the barite is separated and recovered at the bottom flow outlet of the centrifuge.

[0083] Application Examples 16-20

[0084] Application Examples 16-20 are the applications of the barite dispersants obtained in Examples 1-5 of the present invention in the project to improve the purity of barite recovery from waste high-density drilling fluid. If the waste drilling fluid is treated by adding water to the drilling fluid for gel breaking,

[0085] S1: After adding clean water to the waste drilling fluid, stir it for 1 hour at a stirring rate of 3000 r / min.

[0086] S2: 0.5% to 1% of the mass of the original drilling fluid of the barite dispersant obtained in Examples 1-5 was added to the drilling fluid, with the specific addition amount shown in Table 1, and stirred in the mud pool for 1 hour at a stirring rate of 3000 r / min.

[0087] S3: After stirring, the drilling fluid is treated with a low-speed centrifuge at a speed of 1500 r / min, and the barite is separated and recovered at the bottom flow outlet of the centrifuge.

[0088] Comparative Example 1

[0089] This comparative example adopts the method of the above application examples 1-5 to recover barite. Except that the barite dispersant obtained in examples 1-5 is not added during the barite recovery process, other barite recovery process conditions are exactly the same.

[0090] Comparative Example 2

[0091] This comparative example adopts the method of the above application examples 6-10 to recover barite. Except that the barite dispersant obtained in Examples 1-5 is not added during the barite recovery process, other barite recovery process conditions are exactly the same.

[0092] Comparative Example 3

[0093] This comparative example adopts the method of the above application examples 11-15 to recover barite. Except that the barite dispersant obtained in Examples 1-5 is not added during the barite recovery process, other barite recovery process conditions are exactly the same.

[0094] Comparative Example 4

[0095] This comparative example adopts the method of the above application examples 16-20 to recover barite. Except that the barite dispersant obtained in Examples 1-5 is not added during the barite recovery process, other barite recovery process conditions are exactly the same.

[0096] Density evaluation of recovered barite

[0097]

[0098]

[0099] Note: The barite density in the table is in g / cm 3 )

[0100] In summary, the barite dispersant of the present invention can be effectively applied to drilling fluid to improve the density of recovered drilling fluid. From the experimental data, it can be seen that the barite dispersant prepared using Example 3 is most effective in improving the density of recovered barite.

[0101] Any numerical value mentioned in the present invention includes all values that increase by one unit each time from the lowest value to the highest value if there is only a gap of two units between any minimum value and any maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is stated to be 50-90, it is meant in this specification to specifically list values such as 51-89, 52-88... and 69-71 and 70-71. For non-integer values, it is appropriate to consider units of 0.1, 0.01, 0.001 or 0.0001. These are just some special examples. In this application, in a similar manner, all possible combinations of numerical values between the listed lowest value and the listed highest value are considered to have been disclosed.

[0102] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. An application of a barite dispersant in the field of recycling and reusing waste high-density drilling fluid barite, characterized in that, The raw materials of the barite dispersant include, by molar ratio, 60% to 80% of carboxyl monomer and 20% to 40% of sulfonic acid monomer; the amount of the initiator added is 1 to 3 parts based on 100 parts of the monomer mass; The carboxyl monomer includes at least one of acrylic acid and crotonic acid; The sulfonic acid monomer is at least one of sodium vinyl sulfonate, sodium propylene sulfonate, and 2-acrylamide-2-methylpropane sulfonic acid.

2. The use according to claim 1, characterized in that The initiator is potassium persulfate and / or ammonium persulfate.

3. The use according to claim 1 or 2, characterized in that The preparation method of the barite dispersant comprises the following steps: S1: dissolving a carboxyl monomer and a sulfonic acid monomer in water to obtain a carboxyl monomer aqueous solution and a sulfonic acid monomer aqueous solution; S2: mixing the carboxyl monomer aqueous solution and the sulfonic acid monomer aqueous solution obtained in step S1, adjusting the pH value, adding an initiator, and performing a polymerization reaction under nitrogen protection to obtain a polymer; S3: drying and crushing the polymer obtained in step S2 to obtain the barite dispersant; In the step S1, the carboxyl monomer includes at least one of acrylic acid and crotonic acid.

4. The use according to claim 3, characterized in that In the step S1, the sulfonic acid monomer is at least one of sodium vinyl sulfonate, sodium propylene sulfonate, and 2-acrylamide-2-methylpropanesulfonic acid (AMPS).

5. The use according to claim 3, characterized in that In step S1, the mass percentage concentrations of the carboxyl monomer aqueous solution and the sulfonic acid monomer aqueous solution are independently 20-40%.

6. The use according to claim 3, characterized in that In step S2, the volume ratio of the carboxyl monomer aqueous solution to the sulfonic acid monomer aqueous solution is 1:(0.65-1.5).

7. The use according to claim 3, characterized in that In the step S2, the pH value is adjusted to 7-9, and the pH value is adjusted using an alkaline regulator, and the alkaline regulator is potassium hydroxide.

8. The use according to claim 3, characterized in that In step S2, the initiator is potassium persulfate or ammonium persulfate, and the amount of the initiator added is 1% to 3% by mass of the aqueous solution.

9. The use according to claim 3, characterized in that In step S2, the polymerization reaction conditions include: reaction temperature of 15-25° C., stirring rate of 100-150 r / min, and reaction time of 2-4 h.

10. The use according to claim 3, characterized in that In step S3, the viscosity-average molecular weight of the polymer is between 10,000 and 100,000, and the molar ratio of the structural units derived from the carboxylic acid monomer to the structural units derived from the sulfonic acid monomer in the polymer is controlled to be (3-2):(1-2).

11. The use according to claim 1 or 2, characterized in that: The mass fraction of the barite dispersant in the total amount of the waste high-density drilling fluid is 0.5% to 3%.

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