A modifier for treating water-based drilling waste and a method for preparing the same

Abstract

The application relates to the technical field of waste drilling fluid treatment, and discloses a modifier for treating water-based drilling waste and a preparation method thereof; according to weight parts, the raw materials of the modifier include 30-40 parts of potassium persulfate, 10-25 parts of ferric chloride, 20-40 parts of quaternary ammonium cation polymer and 10-20 parts of magnetized modified attapulgite clay. The modifier for treating water-based drilling waste provided in the application solves the problem of incomplete gel breaking in the water-based drilling waste treatment process through synergistic action of various components, forms an oxidation-catalysis-flocculation-magnetic separation four-stage synergistic treatment process, reduces the metal ion content in the liquid phase after solid-liquid separation, makes the liquid phase meet the drilling fluid water preparation requirement without further treatment, simplifies the treatment process and reduces the cost.

Description

Technical Field

[0001] This invention relates to the field of waste drilling fluid treatment technology, and in particular to a modifier for treating water-based drilling waste and its preparation method. Background Technology

[0002] Water-based drilling waste is a complex mixture generated during oil and gas drilling. This complex mixture is a multiphase colloidal-suspension system containing various chemical treatment agents, sewage, oily waste and rock powder. If discharged arbitrarily without treatment, it will cause incalculable harm to the environment.

[0003] Existing methods for treating water-based drilling waste typically involve pretreatment with flocculants, followed by solid-liquid separation, and then resource utilization of the separated waste liquid and rock cuttings.

[0004] The flocculants currently used in the pretreatment process have limited flocculation capacity. After pretreatment of water-based drilling waste, the waste liquid obtained after solid-liquid separation still contains a high concentration of metal ions, which is difficult to meet the requirements of drilling fluid preparation. Therefore, it is necessary to use substances such as ion precipitants to further treat the waste liquid, which makes the treatment process of water-based drilling waste cumbersome and costly. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a modifier for treating water-based drilling waste. By weight, the raw materials include 30-40 parts of potassium persulfate, 10-25 parts of ferric chloride, 20-40 parts of quaternary ammonium cationic polymer, and 10-20 parts of magnetized modified attapulgite clay.

[0006] Optionally, the quaternary ammonium cationic polymer is polyepoxychloropropane-dimethylamine.

[0007] Optionally, the polyepoxychloropropane-dimethylamine is prepared according to the following method: At a temperature not exceeding 5°C, epichlorohydrin is added dropwise to an aqueous solution of dimethylamine, a catalyst is added, and the mixture is reacted at 40-60°C for 5-7 hours. After precipitation with acetone and vacuum drying, polyepoxychlorohydrin-dimethylamine is obtained.

[0008] Optionally, the molar ratio of the dimethylamine to the epichlorohydrin is 1:(1.1-1.5).

[0009] Optionally, the catalyst is sodium hydroxide.

[0010] Optionally, the amount of catalyst added is 0.5% of the total mass of the epichlorohydrin and the dimethylamine.

[0011] Optionally, the preparation method of the magnetized modified attapulgite clay includes the following steps: S01: Acid-activated attapulgite clay is obtained by acidifying attapulgite clay with hydrochloric acid. S02: Disperse the acid-activated attapulgite clay in water, and add ferrous sulfate heptahydrate and ferric chloride hexahydrate under an inert gas atmosphere to obtain reaction mixture I; S03: Add ammonia dropwise to the reaction mixture I until the pH reaches 10, react at 70-90℃, and then perform magnetic separation, washing with ethanol, and drying to obtain magnetized modified attapulgite clay.

[0012] Optionally, the method for preparing the magnetized modified attapulgite clay further includes: S04: The magnetized modified attapulgite clay is dispersed in a solvent, and tetraethyl orthosilicate is added to obtain reaction mixture II; S05: Add ammonia dropwise to the reaction mixture II until the pH is 10, react at 40-60℃, centrifuge and dry to obtain silica-coated magnetized modified attapulgite clay.

[0013] Optionally, the solvent in step S04 is a mixture of ethanol and water.

[0014] Another object of the present invention is to provide a method for preparing the modifier for treating water-based drilling waste as described above, comprising the following steps: S1: Dissolve the quaternary ammonium cationic polymer in water according to the formula amount, add magnetized modified attapulgite clay to obtain dispersion I; S2: Add ferric chloride to dispersion I and stir to obtain dispersion II; S3: Potassium persulfate is added to the dispersion II at a temperature not exceeding 25°C. After the reaction, a viscous complex is obtained. S4: Spray-dry the viscous composite to obtain a modifier for treating water-based drilling waste.

[0015] The embodiments of the present invention have the following technical effects: The modifier for treating water-based drilling waste provided in this application constitutes a four-stage synergistic treatment process of oxidation, catalysis, flocculation, and magnetic separation through the synergistic effect of its components. This solves the problem of incomplete gel breaking in the treatment of water-based drilling waste, reduces the metal ion content in the liquid phase after solid-liquid separation, and enables the liquid phase to meet the water distribution requirements of drilling fluid without further treatment, thus simplifying the treatment process and reducing costs. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are part of this invention.

[0017] To address the cumbersome nature of existing water-based drilling waste treatment processes, this application provides a modifier for treating water-based drilling waste. By weight, the modifier comprises 30-40 parts of potassium persulfate, 10-25 parts of ferric chloride, 20-40 parts of quaternary ammonium cationic polymer, and 10-20 parts of magnetized modified attapulgite clay.

[0018] Water-based drilling waste has a complex composition, typically containing large amounts of polyacrylamide, cellulose, biopolymers such as xanthan gum and other high molecular polymers, bentonite, and organic treatment agents. These substances form a stable colloidal system with high viscosity and colloidal stability. These colloidal systems encapsulate solid particles, forming a colloidal protective layer on their surface, making them difficult to settle and separate. They also prevent particle aggregation through steric hindrance and charge repulsion. Current water-based drilling waste treatment processes typically involve flocculation with inorganic low-molecular-weight, inorganic high-molecular-weight, and organic high-molecular-weight flocculants followed by solid-liquid separation. However, because water-based drilling waste is a colloidal system with high stability and difficulty in adsorption, these flocculants struggle to reach and adsorb onto the surface of solid particles, resulting in poor flocculation. The resulting flocs are small, loose, and difficult to settle, leading to low solid-liquid separation efficiency and turbid supernatant. Consequently, the waste liquid obtained after solid-liquid separation fails to meet the requirements for drilling fluid preparation, necessitating further treatment with ion precipitants and other substances. This makes the water-based drilling waste treatment process cumbersome and costly.

[0019] Based on this, this application provides a composite modifier according to the composition and characteristics of water-based drilling waste. In this composite modifier, potassium persulfate is an oxidizing and de-gelling component that degrades the colloidal structure in water-based drilling waste at the source; quaternary ammonium cationic polymer is a charge neutralizing and bridging component that acts as an organic flocculant to construct high-strength flocs; ferric chloride acts as a free radical catalyst to improve the oxidative de-gelling and destabilizing effect of potassium persulfate, and also acts as an inorganic flocculant that works synergistically with the quaternary ammonium cationic polymer to improve the flocculation effect; magnetized modified attapulgite clay acts as a magnetic carrier and adsorption framework, which accelerates solid-liquid separation, improves treatment efficiency, and also helps to increase floc density.

[0020] Specifically, the reaction mechanism by which the modifier modifies water-based drilling waste in this application is as follows: Potassium persulfate in the presence of Fe provided by ferric chloride 3+ Homogeneous activation occurs under catalysis, generating sulfate radicals (SO4). - The process involves a catalytic system composed of potassium persulfate and ferric chloride to efficiently degrade polymers in waste, thoroughly degrading polymers in water-based drilling waste and degrading the colloidal protective layer on the surface of solid particles in water-based drilling waste, thus achieving delamination and destabilization. Quaternary ammonium cationic polymers act as high-cationic bridging agents to organically flocculate the destabilized water-based drilling waste, neutralizing the charge of destabilized particles and connecting them. Ferric chloride acts as an inorganic flocculant, and magnetized modified attapulgite clay acts as a rigid framework. Through the synergistic effect of quaternary ammonium cationic polymers, ferric chloride, and magnetized modified attapulgite clay, dense flocs are formed. In addition, the magnetized modified attapulgite clay in this application can be recycled and reused, which not only improves the treatment effect but also helps to reduce costs.

[0021] The modifier for treating water-based drilling waste provided in this application constitutes a four-stage synergistic treatment process of oxidation, catalysis, flocculation, and magnetic separation through the synergistic effect of its components. This solves the problem of incomplete gel breaking in the treatment of water-based drilling waste, reduces the metal ion content in the liquid phase after solid-liquid separation, and enables the liquid phase to meet the water distribution requirements of drilling fluid without further treatment, thus simplifying the treatment process and reducing costs.

[0022] The modifier for treating water-based drilling waste provided in this application produces no toxic products during the treatment process and has high safety; ferric chloride also serves as a catalyst and flocculant, and iron ions are recycled, reducing reagent costs.

[0023] Furthermore, this application preferably uses polyepoxychloropropane-dimethylamine as the quaternary ammonium cationic polymer.

[0024] This polyepoxychloropropane-dimethylamine can be purchased directly or made at home.

[0025] To ensure the cationicity of polyepoxychloropropane-dimethylamine and to guarantee the zeta potential, this application preferably uses... Polyepoxychloropropane-dimethylamine is prepared according to the following method: At a temperature not exceeding 5°C, epichlorohydrin is added dropwise to an aqueous solution of dimethylamine, a catalyst is added, and the mixture is reacted at 40-60°C for 5-7 hours. After precipitation with acetone and vacuum drying, polyepoxychlorohydrin-dimethylamine is obtained.

[0026] The preferred mass concentration of the dimethylamine aqueous solution in this application is 40%, the preferred molar ratio of dimethylamine to epichlorohydrin is 1:(1.1-1.5), and the more preferred molar ratio of dimethylamine to epichlorohydrin is 1:1.2.

[0027] The preferred catalyst in this application is sodium hydroxide, and the amount of catalyst added is more preferably 0.5% of the total mass of epichlorohydrin and dimethylamine.

[0028] The preferred method for preparing magnetized modified attapulgite clay in this application includes the following steps: S01: Acid-activated attapulgite clay is obtained by acidifying attapulgite clay with hydrochloric acid. Preferably, attapulgite clay is added to hydrochloric acid, stirred at 70-90℃ for 1-3 hours, washed until neutral, and dried at 100-110℃ to obtain acid-activated attapulgite clay. Preferably, the hydrochloric acid used in this step is 10% hydrochloric acid, and the ratio of attapulgite clay to hydrochloric acid is (90-110) g: 1 L; Acid activation helps to increase the surface area of ​​attapulgite clay; S02: Disperse acid-activated attapulgite clay in water, add ferrous sulfate heptahydrate and ferric chloride hexahydrate under an inert gas atmosphere to obtain reaction mixture I; The preferred solid-liquid ratio of acid-activated attapulgite clay dispersed in water is 1:20, the molar ratio of ferric chloride hexahydrate to ferrous sulfate heptahydrate is 2:1, and the mass ratio of acid-activated attapulgite clay to total iron salts (ferric chloride hexahydrate to ferrous sulfate heptahydrate) is 10:1. S03: Add ammonia water dropwise to reaction mixture I until the pH is 10, react at 70-90℃, and then obtain magnetized modified attapulgite clay by magnetic separation, washing with ethanol and drying.

[0029] To prevent the magnetized modified attapulgite clay from being dissolved and to extend its service life, the preferred preparation method of the magnetized modified attapulgite clay in this application further includes: S04: Magnetized modified attapulgite clay is dispersed in a solvent, and tetraethyl orthosilicate is added to obtain reaction mixture II; The preferred mass ratio of magnetized modified attapulgite clay to solvent is (2-5):100; the amount of tetraethyl orthosilicate added is 10% of the mass of magnetized modified attapulgite clay to solvent. S05: Add ammonia dropwise to reaction mixture II until the pH reaches 10, react at 40-60℃, centrifuge and dry to obtain silica-coated magnetized modified attapulgite clay.

[0030] The solvent in step S04 of this application is preferably a mixture of ethanol and water, and more preferably a mixture of ethanol and water in a volume ratio of 4:1.

[0031] This application introduces a silica coating layer on the outside of magnetized modified attapulgite clay, which on the one hand inhibits the corrosion reaction of iron oxide, and on the other hand isolates hydrogen ions through the silica layer, reducing the magnetic loss rate, thereby helping to extend its service life.

[0032] This application introduces silica-coated magnetized attapulgite clay, which allows the quaternary ammonium cationic polymer to react with Fe... 3+ Anchored on the surface of attapulgite clay, it forms a magnetic carrier-flocculator composite, with the particles connected by flexible long chains of quaternary ammonium cationic polymers and the silica-coated magnetized modified attapulgite clay serving as a rigid skeleton, forming a structure that combines rigidity and flexibility, synergistically improving flocculation effect and flocculation efficiency.

[0033] Another object of the present invention is to provide a method for preparing the modifier for treating water-based drilling waste as described above, the method comprising the following steps: S1: Dissolve the quaternary ammonium cationic polymer in water according to the formula amount, preferably dissolving the quaternary ammonium cationic polymer in deionized water at 40°C, and preferably the mass ratio of quaternary ammonium cationic polymer to water is 2:3. Then add magnetized modified attapulgite clay, which can be silica-coated magnetized modified attapulgite clay. Preferably, it is ultrasonically dispersed at 300W for 20 minutes to obtain dispersion I. S2: Add ferric chloride to dispersion I, preferably slowly add a 20% ferric chloride solution to dispersion I, stir and mix to obtain dispersion II; S3: Add potassium persulfate to dispersion II at a temperature not exceeding 25°C. After the reaction, preferably after a constant temperature reaction for 2 hours, a viscous complex is obtained. S4: The viscous compound is spray-dried to obtain a modifier for treating water-based drilling waste; The preferred inlet air temperature for spray drying is 180°C, and the outlet air temperature is 80°C, resulting in a light yellow powdery product, which is the modifier for treating water-based drilling waste.

[0034] In this preparation process, the amino groups in the quaternary ammonium cationic polymer form hydrogen bonds with the surface hydroxyl groups of the magnetized attapulgite clay, resulting in the uniform coating of the magnetized attapulgite clay by the quaternary ammonium cationic polymer, forming an organic-inorganic precomplex; by slowly adding ferric chloride solution, Fe... 3+ Electrostatic complexation with the quaternary ammonium groups of the quaternary ammonium cationic polymer increases the cation density and improves the flocculation effect. To inhibit the thermal decomposition of potassium persulfate, this application preferably adds potassium persulfate at a temperature not exceeding 25°C. Furthermore, to avoid the generation of a small amount of sulfate free radicals after the addition of potassium persulfate, which attack the quaternary ammonium cationic polymer chain and cause chain breakage, it is preferred to add potassium persulfate at the end of the preparation process.

[0035] After the isothermal reaction in step S3 at a temperature not exceeding 25°C, Fe 3+ The quaternary ammonium cationic polymer is bridged to the hydroxyl groups on the surface of attapulgite clay to form a three-dimensional network structure, which enhances the flocculation skeleton. Then, it is spray-dried to dehydrate and solidify and quench free radicals, which deactivates the residual oxidant and prevents the modifier from becoming ineffective during storage. At the same time, the quaternary ammonium cationic polymer is thermally crosslinked, and hydrogen bonds are formed between the molecular chains to enhance rigidity, so that the magnetized modified attapulgite clay is surrounded by the polymer and forms a stable powder.

[0036] The modifier obtained by the preparation method provided in this application retains most of the potassium persulfate in the raw material as it remains stable, thus preserving its oxidative activity. When used to modify water-based drilling waste, it can reactivate sulfate free radicals upon contact with water, effectively oxidizing and destabilizing the colloidal system. Quaternary ammonium cationic polymers, Fe... 3+ It forms a cross-linked network with magnetized modified attapulgite clay to improve flocculation effect and increase floc density.

[0037] The preparation process provided in this application, through stepwise feeding and low-temperature control, effectively avoids side reactions while enabling the oxidizing component in the prepared modifier to directionally degrade the colloid, and the flocculating component to be loaded on a magnetic carrier, thereby enabling the prepared modifier to have both excellent decolloid breaking activity and flocculation performance.

[0038] The method for preparing a modifier for treating water-based drilling waste provided in this application controls the feeding sequence and temperature, enabling the prepared modifier to form a four-stage synergistic treatment process of oxidation-catalysis-flocculation-magnetic separation through the synergistic effect of its components. This solves the problem of incomplete gel breaking in the treatment of water-based drilling waste, reduces the metal ion content in the liquid phase after solid-liquid separation, and allows the liquid phase to meet the water distribution requirements of drilling fluid without further treatment, simplifying the treatment process and reducing costs.

[0039] The modifier prepared in this application achieves efficient synergy of four components through a segmented composite process, and is particularly suitable for high-stability polysulfonated drilling fluid waste.

[0040] The modifier provided in this application can modify water-based drilling waste using the following method: Under pH conditions of 3-4, a modifier was added to the water-based drilling waste at a ratio of (1.2-1.8) g / L to the amount of modifier added. After reacting at 50℃ for 30 min, the mixture was stirred at 40 rpm for 20 min and then centrifuged to obtain a clear liquid and solid residue.

[0041] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, specific embodiments of this application are described in detail below.

[0042] Unless otherwise specified, the polyepoxychloropropane-dimethylamine in the embodiments and comparative examples of this application is prepared according to the following method: At a temperature not exceeding 5°C, epichlorohydrin was added dropwise to a 40% (w / w) aqueous solution of dimethylamine, with a molar ratio of dimethylamine to epichlorohydrin of 1:1.2. Sodium hydroxide of 0.5% (w / w) of the total mass of epichlorohydrin and dimethylamine was added, and the mixture was reacted at 50°C for 6 hours. After precipitation with acetone and vacuum drying, polyepoxychlorohydrin-dimethylamine was obtained.

[0043] Magnetized modified attapulgite clay was prepared according to the following method: S01: Add attapulgite clay to hydrochloric acid (10% hydrochloric acid), with a ratio of attapulgite clay to hydrochloric acid of 100g:1L. Stir at 80℃ for 2 hours, wash until neutral, and dry at 105℃ to obtain acid-activated attapulgite clay. S02: Acid-activated attapulgite clay is dispersed in water at a solid-liquid ratio of 1:20. Ferrous sulfate heptahydrate and ferric chloride hexahydrate are added under a nitrogen atmosphere. The molar ratio of ferric chloride hexahydrate to ferrous sulfate heptahydrate is 2:1. The mass ratio of acid-activated attapulgite clay to total iron salt (ferric chloride hexahydrate and ferrous sulfate heptahydrate) is 10:1 to obtain reaction mixture I. S03: Add ammonia water dropwise to reaction mixture I until the pH is 10, react at 80℃ for 1 h, and then obtain magnetized modified attapulgite clay by magnetic separation, washing with ethanol and drying. S04: Magnetized modified attapulgite clay is dispersed in a solvent, which is a mixture of ethanol and water in a volume ratio of 4:1 and the mass ratio of magnetized modified attapulgite clay to solvent is 3:100. Tetraethyl orthosilicate is added, and the amount of tetraethyl orthosilicate added is 10% of the mass of magnetized modified attapulgite clay to solvent, to obtain reaction mixture II. S05: Add ammonia water dropwise to reaction mixture II until the pH is 10, react at 50℃ for 6 hours, and then centrifuge and dry to obtain silica-coated magnetized modified attapulgite clay.

[0044] Example 1

[0045] This embodiment provides a method for preparing a modifier for treating water-based drilling waste, comprising the following steps: S1: According to the weight parts, 30 parts of polyepoxychloropropane-dimethylamine were dissolved in 45 parts of deionized water at 40℃, and then 15 parts of silica-coated magnetized modified attapulgite clay were added. The mixture was ultrasonically dispersed at 300W for 20 minutes to obtain dispersion I. S2: Prepare a 20% ferric chloride solution by mixing 20 parts of ferric chloride. Slowly add the ferric chloride solution to dispersion I and stir at 200 rpm for 10 min to obtain dispersion II. S3: Control the temperature to be no higher than 25℃ by using an ice bath, add 35 parts of potassium persulfate to dispersion II, and react at a constant temperature for 2 hours to obtain a viscous complex; S4: The viscous compound was spray-dried at an inlet air temperature of 180℃ and an outlet air temperature of 80℃ to obtain a modifier for treating water-based drilling waste.

[0046] Example 2

[0047] This embodiment provides a method for preparing a modifier for treating water-based drilling waste, comprising the following steps: S1: According to the weight parts, 20 parts of polyepoxychloropropane-dimethylamine were dissolved in 45 parts of deionized water at 40℃, and then 10 parts of silica-coated magnetized modified attapulgite clay were added. The mixture was ultrasonically dispersed at 300W for 20 minutes to obtain dispersion I. S2: Prepare a 20% ferric chloride solution by mixing 10 parts of ferric chloride. Slowly add the ferric chloride solution to dispersion I and stir at 200 rpm for 10 min to obtain dispersion II. S3: Control the temperature to be no higher than 25℃ by using an ice bath, add 30 parts of potassium persulfate to dispersion II, and react at a constant temperature for 2 hours to obtain a viscous complex; S4: The viscous compound was spray-dried at an inlet air temperature of 180℃ and an outlet air temperature of 80℃ to obtain a modifier for treating water-based drilling waste.

[0048] Example 3

[0049] This embodiment provides a method for preparing a modifier for treating water-based drilling waste, comprising the following steps: S1: According to the weight parts, 40 parts of polyepoxychloropropane-dimethylamine were dissolved in 45 parts of deionized water at 40℃, and then 20 parts of silica-coated magnetized modified attapulgite clay were added. The mixture was ultrasonically dispersed at 300W for 20 minutes to obtain dispersion I. S2: Prepare a 20% ferric chloride solution by mixing 25 parts of ferric chloride. Slowly add the ferric chloride solution to dispersion I and stir at 200 rpm for 10 min to obtain dispersion II. S3: Control the temperature to be no higher than 25℃ by using an ice bath, add 40 parts of potassium persulfate to dispersion II, and react at a constant temperature for 2 hours to obtain a viscous complex; S4: The viscous compound was spray-dried at an inlet air temperature of 180℃ and an outlet air temperature of 80℃ to obtain a modifier for treating water-based drilling waste.

[0050] All comparative examples in this application are compared with Example 1.

[0051] Comparative Example 1 This comparative example provides a method for preparing a modifier for treating water-based drilling waste, comprising the following steps: S1: According to the weight parts, 15 parts of silica-coated magnetized attapulgite clay were dissolved in 45 parts of deionized water at 40℃ and ultrasonically dispersed at 300W for 20min to obtain dispersion I. S2: Prepare a 20% ferric chloride solution by mixing 20 parts of ferric chloride. Slowly add the ferric chloride solution to dispersion I and stir at 200 rpm for 10 min to obtain dispersion II. S3: Control the temperature to be no higher than 25℃ by using an ice bath, add 35 parts of potassium persulfate to dispersion II, and react at a constant temperature for 2 hours to obtain a viscous complex; S4: The viscous compound was spray-dried at an inlet air temperature of 180℃ and an outlet air temperature of 80℃ to obtain a modifier for treating water-based drilling waste.

[0052] Comparative Example 2 This comparative example provides a method for preparing a modifier for treating water-based drilling waste, comprising the following steps: S1: According to the weight parts, 30 parts of polyepoxychloropropane-dimethylamine were dissolved in 45 parts of deionized water at 40℃, and then 15 parts of silica-coated magnetized modified attapulgite clay were added. The mixture was ultrasonically dispersed at 300W for 20 minutes to obtain dispersion I. S2: Control the temperature to be no higher than 25℃ by using an ice bath, add 35 parts of potassium persulfate to dispersion I, and react at a constant temperature for 2 hours to obtain a viscous complex; S3: The viscous compound was spray-dried at an inlet air temperature of 180℃ and an outlet air temperature of 80℃ to obtain a modifier for treating water-based drilling waste.

[0053] The modifiers prepared according to the above embodiments and comparative examples were used to treat water-based drilling waste according to the following method: Under pH conditions of 3-4, a modifier was added to water-based drilling waste at a ratio of 5 g / L to the amount of water-based drilling waste. After reacting at 50°C for 30 min, the mixture was stirred at 40 rpm for 20 min and then centrifuged to obtain filtrate and solid residue.

[0054] Among them, water-based drilling waste is polysulfonate drilling fluid waste, with a water content of 60% and a density of 1.45 g / cm3.

[0055] The filtrates obtained after modification with the modifiers in the above embodiments and comparative examples were evaluated according to GB / T 16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids".

[0056] The test was conducted, and the results are shown in Table 1: Table 1

[0057] The solid residues obtained after modification with the modifiers in the above embodiments and comparative examples were tested according to the standard or method: "Pollution Control Requirements for Comprehensive Utilization of Solid Waste from Oil and Gas Field Drilling" (DB 65 / T 3997-1997). The test results are shown in Table 2. Table 2

[0058] As shown in Tables 1 and 2, after treating water-based drilling waste with the modifier provided in this application, the resulting filtrate meets the requirements for drilling fluid preparation and can be directly reused without further deep treatment. The modified rock cuttings are entirely converted into reduced soil, meeting the pollution control requirements for comprehensive utilization of solid waste from oil and gas field drilling (DB 65 / T3997-1997). The reduced soil can be directly used for well access road construction, well site paving, and pit filling.

[0059] The difference between Comparative Example 1 and Example 1 is that polyepoxychloropropane-dimethylamine was not added. Because effective flocculation could not be carried out, the metal ions in the solid phase after solid-liquid separation increased compared with Example 1, the water content increased, and the various properties in the liquid phase could not meet the requirements for direct reuse.

[0060] The difference between Comparative Example 2 and Example 1 is that ferric chloride was not added. Because it could not effectively catalyze potassium persulfate and lacked inorganic flocculants, the amount of flocs was significantly reduced for the same flocculation time. Although the performance data of the product was slightly better than that of Comparative Example 1, it was still significantly lower than that of Example 1 and could not be directly reused.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A modifier for treating water-based drilling waste, characterized in that, By weight, the raw materials include: 30-40 parts potassium persulfate, 10-25 parts ferric chloride, 20-40 parts quaternary ammonium cationic polymer, and 10-20 parts magnetized modified attapulgite clay. The quaternary ammonium cationic polymer is polyepoxychloropropane-dimethylamine; The preparation method of the magnetized modified attapulgite clay includes the following steps: S01: Acid-activated attapulgite clay is obtained by acidifying attapulgite clay with hydrochloric acid. S02: Disperse the acid-activated attapulgite clay in water, and add ferrous sulfate heptahydrate and ferric chloride hexahydrate under an inert gas atmosphere to obtain reaction mixture I; S03: Add ammonia water dropwise to the reaction mixture I until the pH is 10, react at 70-90℃, and then obtain magnetized modified attapulgite clay by magnetic separation, washing with ethanol and drying. S04: The magnetized modified attapulgite clay is dispersed in a solvent, and tetraethyl orthosilicate is added to obtain reaction mixture II; S05: Add ammonia dropwise to the reaction mixture II until the pH is 10, react at 40-60℃, centrifuge and dry to obtain silica-coated magnetized modified attapulgite clay.

2. The modifier for treating water-based drilling waste according to claim 1, characterized in that, The polyepoxychloropropane-dimethylamine was prepared according to the following method: At a temperature not exceeding 5°C, epichlorohydrin is added dropwise to an aqueous solution of dimethylamine, a catalyst is added, and the mixture is reacted at 40-60°C for 5-7 hours. After precipitation with acetone and vacuum drying, polyepoxychlorohydrin-dimethylamine is obtained.

3. The modifier for treating water-based drilling waste according to claim 2, characterized in that, The molar ratio of dimethylamine to epichlorohydrin is 1:(1.1-1.5).

4. The modifier for treating water-based drilling waste according to claim 2, characterized in that, The catalyst is sodium hydroxide.

5. The modifier for treating water-based drilling waste according to claim 4, characterized in that, The catalyst is added at a rate of 0.5% of the total mass of the epichlorohydrin and the dimethylamine.

6. The modifier for treating water-based drilling waste according to claim 1, characterized in that, The solvent in step S04 is a mixture of ethanol and water.

7. A method for preparing a modifier for treating water-based drilling waste as described in any one of claims 1-6, characterized in that, The steps include the following: S1: Dissolve the quaternary ammonium cationic polymer in water according to the formula amount, add magnetized modified attapulgite clay to obtain dispersion I; S2: Add ferric chloride to dispersion I and stir to obtain dispersion II; S3: Potassium persulfate is added to the dispersion II at a temperature not exceeding 25°C. After the reaction, a viscous complex is obtained. S4: Spray-dry the viscous composite to obtain a modifier for treating water-based drilling waste.

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