Modifier for treating water-based drilling waste and preparation method thereof

Abstract

The invention 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.The modifier is prepared from, by weight, 30-40 parts of potassium persulfate, 10-25 parts of ferric trichloride, 20-40 parts of quaternary ammonium cationic polymer and 10-20 parts of magnetized modified attapulgite clay. According to the modifier for treating the water-based drilling waste, through the synergistic effect of all the components, an oxidation-catalysis-flocculation-magnetic separation four-stage synergistic treatment process is formed, the problem that gel breaking is not thorough in the water-based drilling waste treatment process is solved, the content of metal ions in a liquid phase after solid-liquid separation is reduced, and the water-based drilling waste treatment effect is improved. The water distribution requirement of the drilling fluid can be met under the condition that the liquid phase does not need to be further treated, the treatment process is simplified, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of waste drilling fluid treatment, in particular to a modifier for treating water-based drilling waste and a preparation method thereof. Background Art

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

[0003] Existing methods for treating water-based drilling waste generally involve pre-treatment with flocculants, followed by solid-liquid separation, and then resource utilization of the separated waste liquid and 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 through solid-liquid separation still contains a high concentration of metal ions, which is difficult to meet the requirements of drilling fluid water distribution. Therefore, it is necessary to use ion precipitants and other substances to further treat the waste liquid, resulting in a cumbersome and costly treatment process for water-based drilling waste. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a modifier for treating water-based drilling waste. 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, calculated by weight.

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

[0007] Optionally, the polyepichlorohydrin-dimethylamine is prepared according to the following method: At a temperature not higher than 5°C, epichlorohydrin is added dropwise to a dimethylamine aqueous solution, a catalyst is added, and the mixture is reacted at 40-60°C for 5-7 hours. The mixture is precipitated with acetone and vacuum dried to obtain polyepichlorohydrin-dimethylamine.

[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 added amount of the catalyst is 0.5% of the total mass of the epichlorohydrin and the dimethylamine.

[0011] Optionally, the preparation method of the magnetized modified attapulgite clay comprises the following steps: S01: acidifying attapulgite clay with hydrochloric acid to obtain acid-activated attapulgite clay; S02: dispersing the acid-activated attapulgite clay in water, adding ferrous sulfate heptahydrate and ferric chloride hexahydrate in an inert gas atmosphere to obtain a reaction mixture I; S03: adding aqueous ammonia to the reaction mixture I until the pH reaches 10, reacting at 70-90° C., magnetic separation, ethanol washing, and drying to obtain magnetized modified attapulgite clay.

[0012] Optionally, the preparation method of the magnetized modified attapulgite clay further comprises: S04: dispersing the magnetized modified attapulgite clay in a solvent, and adding ethyl orthosilicate to obtain a reaction mixture II; S05: adding aqueous ammonia to the reaction mixture II until the pH reaches 10, reacting at 40-60° C., and centrifugally drying 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 above-mentioned modifier for treating water-based drilling waste, comprising the following steps: S1: Dissolving the quaternary ammonium cationic polymer in water according to the formula, and adding magnetized modified attapulgite clay to obtain dispersion I; S2: adding ferric chloride to the dispersion I and stirring to obtain dispersion II; S3: adding potassium persulfate to the dispersion II at a temperature not higher than 25° C. to react and obtain a viscous composite; S4: spray-drying 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 the present application, through the synergistic action of various components, constitutes a four-stage synergistic treatment process of oxidation-catalysis-flocculation-magnetic separation, which solves the problem of incomplete gel breaking during 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 drilling fluid water distribution requirements without further treatment, thereby simplifying the treatment process and reducing costs. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are considered to be within the scope of the present invention.

[0017] Based on the problem of cumbersome existing water-based drilling waste treatment process, the present application provides a modifier for treating water-based drilling waste. 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 cationic polymer, and 10-20 parts of magnetized modified attapulgite clay, calculated by weight.

[0018] The composition of water-based drilling waste is complex, usually containing a large amount 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 wrap around solid particles, forming a colloidal protective layer on the surface of the solid particles, making it difficult for them to settle and separate, and preventing particle aggregation through steric hindrance effect and charge repulsion effect; in the existing water-based drilling waste treatment process, flocculation treatment is usually carried out by using flocculants such as inorganic low molecular weight, inorganic high molecular weight, and organic high molecular weight before solid-liquid separation. Because water-based drilling waste is a colloidal system with high stability and high difficulty, it is difficult for these flocculants to approach and adsorb to the surface of solid particles in water-based drilling waste, resulting in poor flocculation effect, and the flocs formed are small, loose, and not easy to settle. The solid-liquid separation efficiency is low, and the supernatant is turbid. Therefore, the waste liquid obtained by solid-liquid separation is difficult to meet the requirements of drilling fluid water distribution, and it is necessary to use ion precipitants and other substances to treat the waste liquid, resulting in a cumbersome and costly treatment process for water-based drilling waste.

[0019] Based on this, the present application provides a composite modifier according to the components and characteristics of water-based drilling waste. In the composite modifier, potassium persulfate is an oxidative gel-breaking component, which degrades the colloidal structure in the water-based drilling waste from the source; quaternary ammonium cationic polymer is a charge neutralization and bridging component, which serves as an organic flocculant to construct high-strength flocs; ferric chloride, on the one hand, acts as a free radical catalyst to improve the oxidative gel-breaking and destabilization effect of potassium persulfate; on the other hand, it acts as an inorganic flocculant, synergistically with the quaternary ammonium cationic polymer to improve the flocculation effect; magnetized modified attapulgite clay serves as a magnetic carrier and adsorption skeleton, which accelerates solid-liquid separation, improves treatment efficiency, and also helps to increase floc density.

[0020] Specifically, the reaction mechanism of the modifier in this application for modifying water-based drilling waste is as follows: Potassium persulfate provides Fe in ferric chloride 3+ Homogeneous activation occurs under catalysis to generate sulfate radicals (SO4 - ·), a linkage catalytic system is formed by potassium persulfate and ferric chloride to efficiently degrade polymers in the waste, completely degrade polymers in water-based drilling waste, degrade the colloidal protective layer on the surface of solid particles in the water-based drilling waste, and achieve gel breaking and destabilization; quaternary ammonium cationic polymers are used as high cationic bridges to organically flocculate the water-based drilling waste after gel breaking and destabilization, neutralize the charge of the destabilized particles, and connect the particles; ferric chloride is used as an inorganic flocculant, and magnetized modified attapulgite clay is used as a rigid skeleton. The quaternary ammonium cationic polymer, ferric chloride and magnetized modified attapulgite clay work synergistically to form dense flocs; in addition, the magnetized modified attapulgite clay in the present 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 the present application, through the synergistic action of various components, constitutes a four-stage synergistic treatment process of oxidation-catalysis-flocculation-magnetic separation, which solves the problem of incomplete gel breaking during 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 drilling fluid water distribution requirements without further treatment, thereby simplifying the treatment process and reducing costs.

[0022] The modifier provided in the present application for treating water-based drilling waste produces no toxic products during the treatment process and is highly safe; ferric chloride acts as both a catalyst and a flocculant, and iron ions are recycled, reducing the cost of the agent.

[0023] Furthermore, the present application prefers that the quaternary ammonium cationic polymer is polyepichlorohydrin-dimethylamine.

[0024] The polyepichlorohydrin-dimethylamine can be purchased directly or made at home.

[0025] In order to ensure the cationicity of polyepichlorohydrin-dimethylamine and to ensure the Zeta potential, the present application preferably Polyepichlorohydrin-dimethylamine was prepared as follows: At a temperature not higher than 5°C, epichlorohydrin is added dropwise to a dimethylamine aqueous solution, a catalyst is added, and the mixture is reacted at 40-60°C for 5-7 hours. The mixture is precipitated with acetone and vacuum dried to obtain polyepichlorohydrin-dimethylamine.

[0026] The present application preferably has a mass concentration of 40% of the dimethylamine aqueous solution, preferably has a molar ratio of dimethylamine to epichlorohydrin of 1:(1.1-1.5), and further preferably has a molar ratio of dimethylamine to epichlorohydrin of 1:1.2.

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

[0028] The preparation method of the magnetized modified attapulgite clay preferably comprises the following steps: S01: acidifying attapulgite clay with hydrochloric acid to obtain acid-activated attapulgite clay; Preferably, attapulgite clay is added to hydrochloric acid, stirred at 70-90° C. for 1-3 hours, washed until neutral, and dried at 100-110° C. to obtain acid-activated attapulgite clay; Preferably, the hydrochloric acid 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: dispersing acid-activated attapulgite clay in water, adding ferrous sulfate heptahydrate and ferric chloride hexahydrate under an inert gas atmosphere to obtain a reaction mixture I; Preferably, when the acid-activated attapulgite clay is dispersed in water, the solid-liquid ratio is 1:20, the molar ratio of ferric chloride hexahydrate to ferrous sulfate heptahydrate is 2:1, and the mass ratio of the acid-activated attapulgite clay to the total iron salt (ferric chloride hexahydrate and ferrous sulfate heptahydrate) is 10:1; S03: Ammonia water is added dropwise to the reaction mixture I until the pH reaches 10, and the mixture is reacted at 70-90° C., followed by magnetic separation, ethanol washing, and drying to obtain magnetized modified attapulgite clay.

[0029] In order to prevent the magnetized modified attapulgite clay from being dissolved and extend its service life, the preparation method of the magnetized modified attapulgite clay preferably further comprises: S04: dispersing the magnetized modified attapulgite clay in a solvent, and adding ethyl orthosilicate to obtain a reaction mixture II; The preferred mass ratio of the magnetized modified attapulgite clay to the solvent is (2-5):100; the amount of ethyl orthosilicate added is 10% of the mass of the magnetized modified attapulgite clay and the solvent; S05: adding aqueous ammonia to the reaction mixture II until the pH reaches 10, reacting at 40-60° C., and centrifugally drying to obtain silica-coated magnetized modified attapulgite clay.

[0030] In the present application, the solvent in step S04 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] The present application introduces a silica coating layer on the outside of the magnetized modified attapulgite clay, which, on the one hand, suppresses the corrosion reaction of ferroferric 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] The present invention introduces silica-coated magnetized attapulgite clay to make the quaternary ammonium cationic polymer and Fe 3+ Anchored on the surface of attapulgite clay, a magnetic carrier-flocculant complex is formed, and the particles are connected by flexible long-chain bridging of quaternary ammonium cationic polymers. The silica-coated magnetized modified attapulgite clay serves as a rigid skeleton, forming a rigid and flexible structure that synergistically improves the flocculation effect and efficiency.

[0033] Another object of the present invention is to provide a method for preparing the above-mentioned modifier for treating water-based drilling waste, the preparation method comprising the following steps: S1: dissolving a quaternary ammonium cationic polymer in water according to the formula, preferably dissolving the quaternary ammonium cationic polymer in deionized water at 40° C., and preferably having a mass ratio of the quaternary ammonium cationic polymer to water of 2:3, and then adding magnetized modified attapulgite clay, which may be silica-coated magnetized modified attapulgite clay, and preferably ultrasonically dispersing the mixture at 300 W for 20 minutes to obtain dispersion I; S2: adding ferric chloride to dispersion I, preferably slowly adding a 20% ferric chloride solution to dispersion I, stirring and mixing to obtain dispersion II; S3: adding potassium persulfate to dispersion II at a temperature not higher than 25°C, and reacting, preferably at a constant temperature for 2 hours, to obtain a viscous composite; S4: spray drying the viscous composite to obtain a modifier for treating water-based drilling waste; The preferred spray drying air inlet temperature is 180° C. and the air outlet temperature is 80° C. to obtain a light yellow powdery product, which is a modifier for treating water-based drilling waste.

[0034] During the preparation process, the amino groups in the quaternary ammonium cationic polymer form hydrogen bonds with the surface hydroxyl groups of the magnetized modified attapulgite clay, so that the quaternary ammonium cationic polymer uniformly coats the magnetized modified attapulgite clay to form an organic-inorganic pre-complex. By slowly adding ferric chloride solution, Fe 3+ Electrostatic complexation with the quaternary ammonium groups of the quaternary ammonium cationic polymer increases the cationic density and improves the flocculation effect; to inhibit the thermal decomposition of potassium persulfate, the present application preferably adds persulfate at a temperature not higher than 25°C; and to avoid the small amount of sulfate radicals generated after the addition of potassium persulfate attacking the quaternary ammonium cationic polymer chain and causing chain scission, potassium persulfate is preferably added last in the preparation process.

[0035] After the constant temperature reaction at no higher than 25°C in step S3, Fe 3+ The quaternary ammonium cationic polymer is bridged with the hydroxyl groups on the surface of the attapulgite clay to form a three-dimensional network structure, which strengthens the flocculation skeleton. The polymer is then spray-dried, dehydrated, solidified, and free radical quenched to inactivate the residual oxidant, preventing continued reaction during storage that could cause the modifier to become ineffective. At the same time, the quaternary ammonium cationic polymer is thermally cross-linked, forming hydrogen bonds between the molecular chains to enhance rigidity, so that the magnetized modified attapulgite clay is surrounded by the polymer, forming a powder with stable performance.

[0036] The modifier obtained by the preparation method provided by the present application has most of the potassium persulfate in the raw material not decomposed and exists in a stable form, so that the oxidative activity of the modifier is retained. When the water-based drilling waste is modified, the sulfate radical can be reactivated by water, thereby effectively oxidizing and destabilizing the colloidal system; quaternary ammonium cationic polymer, Fe 3+ It forms a cross-linked network with magnetized modified attapulgite clay to improve the flocculation effect and increase the floc density.

[0037] The preparation process provided in this application, through step-by-step 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 flocculation component to be loaded on the magnetic carrier, thereby enabling the prepared modifier to have both excellent gel-breaking activity and flocculation performance.

[0038] The method for preparing a modifier for treating water-based drilling waste provided in the present application controls the order of adding materials and the temperature, so that the prepared modifier for treating water-based drilling waste, through the synergistic action of the various components, constitutes a four-stage synergistic treatment process of oxidation-catalysis-flocculation-magnetic separation, thereby solving the problem of incomplete gel breaking during the treatment of water-based drilling waste, reducing the metal ion content in the liquid phase after solid-liquid separation, and allowing the liquid phase to meet the drilling fluid water distribution requirements without further treatment, thereby simplifying the treatment process and reducing costs.

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

[0040] The modifier provided in this application can be used to modify water-based drilling waste in the following manner: Under the condition of pH 3-4, a modifier is added to the water-based drilling waste, and the addition ratio of the modifier to the water-based drilling waste is (1.2-1.8) g / L; after reacting at 50°C for 30 minutes, stirring at 40 rpm for 20 minutes, and centrifuging to obtain a clear liquid and a solid residue.

[0041] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below.

[0042] Unless otherwise specified, the polyepichlorohydrin-dimethylamine in each example and comparative example of the present application was prepared as follows: At a temperature not higher than 5°C, epichlorohydrin is added dropwise to a 40% by mass dimethylamine aqueous solution, with a molar ratio of dimethylamine to epichlorohydrin of 1:1.2; sodium hydroxide (0.5% by mass of the total weight of epichlorohydrin and dimethylamine) is added, and the mixture is reacted at 50°C for 6 hours, precipitated with acetone, and dried in vacuo to obtain polyepichlorohydrin-dimethylamine.

[0043] The magnetized modified attapulgite clay was prepared as follows: S01: adding attapulgite clay to hydrochloric acid, wherein the hydrochloric acid is 10% hydrochloric acid and the dosage ratio of attapulgite clay to hydrochloric acid is 100 g:1 L, stirring at 80° C. for 2 h, washing to neutrality, and drying at 105° C. to obtain acid-activated attapulgite clay; S02: Acid-activated attapulgite clay was dispersed in water at a solid-liquid ratio of 1:20, and ferrous sulfate heptahydrate and ferric chloride hexahydrate were added under a nitrogen atmosphere, wherein the molar ratio of ferric chloride hexahydrate to ferrous sulfate heptahydrate was 2:1, and the mass ratio of acid-activated attapulgite clay to total iron salts (ferric chloride hexahydrate and ferrous sulfate heptahydrate) was 10:1, to obtain a reaction mixture I; S03: Ammonia water was added dropwise to the reaction mixture I until the pH was 10, and the mixture was reacted at 80°C for 1 hour, followed by magnetic separation, washing with ethanol, and drying to obtain magnetized modified attapulgite clay; S04: dispersing the magnetized modified attapulgite clay in a solvent, wherein the solvent is a mixture of ethanol and water in a volume ratio of 4:1, and the mass ratio of the magnetized modified attapulgite clay to the solvent is 3:100, and adding ethyl orthosilicate in an amount of 10% of the mass of the magnetized modified attapulgite clay and the solvent, to obtain a reaction mixture II; S05: Aqueous ammonia was added dropwise to the reaction mixture II until the pH value reached 10, and the mixture was reacted at 50° C. for 6 h, followed by centrifugal drying 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: Dissolve 30 parts of polyepichlorohydrin-dimethylamine in 45 parts of deionized water at 40°C, add 15 parts of silica-coated magnetized attapulgite clay, and disperse the mixture at 300W ultrasonic wave for 20 minutes to obtain dispersion I. S2: Prepare a 20% ferric chloride solution by adding 20 parts of ferric chloride to the dispersion I slowly, stirring at 200 rpm for 10 min to obtain dispersion II; S3: Control the temperature to no higher than 25°C in an ice bath, add 35 parts of potassium persulfate to dispersion II, and react at this temperature for 2 hours to obtain a viscous composite. S4: spray drying the viscous composite at an air inlet temperature of 180° C. and an air outlet temperature of 80° C. 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: Dissolve 20 parts of polyepichlorohydrin-dimethylamine in 45 parts of deionized water at 40°C, add 10 parts of silica-coated magnetized attapulgite clay, and disperse the mixture at 300W ultrasonic wave for 20 minutes to obtain dispersion I. S2: Prepare a 20% ferric chloride solution by adding 10 parts of ferric chloride to the dispersion I, and stir at 200 rpm for 10 minutes to obtain dispersion II; S3: Control the temperature to no higher than 25°C in an ice bath, add 30 parts of potassium persulfate to dispersion II, and react at this temperature for 2 hours to obtain a viscous composite. S4: spray drying the viscous composite at an air inlet temperature of 180° C. and an air outlet temperature of 80° C. 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: Dissolve 40 parts of polyepichlorohydrin-dimethylamine in 45 parts of deionized water at 40°C, add 20 parts of silica-coated magnetized attapulgite clay, and disperse the mixture at 300W ultrasonic wave for 20 minutes to obtain dispersion I. S2: Prepare a 20% ferric chloride solution by adding 25 parts of ferric chloride to the dispersion I, and stir at 200 rpm for 10 minutes to obtain dispersion II; S3: Add 40 parts of potassium persulfate to dispersion II by controlling the temperature to no higher than 25°C in an ice bath, and react at this temperature for 2 hours to obtain a viscous composite. S4: spray drying the viscous composite at an air inlet temperature of 180° C. and an air outlet temperature of 80° C. to obtain a modifier for treating water-based drilling waste.

[0050] The comparative examples in this application are all 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: Dissolve 15 parts by weight of silica-coated magnetized attapulgite clay in 45 parts of deionized water at 40°C, and disperse the mixture at 300W ultrasonic wave for 20 minutes to obtain dispersion I. S2: Prepare a 20% ferric chloride solution by adding 20 parts of ferric chloride to the dispersion I slowly, stirring at 200 rpm for 10 min to obtain dispersion II; S3: Control the temperature to no higher than 25°C in an ice bath, add 35 parts of potassium persulfate to dispersion II, and react at this temperature for 2 hours to obtain a viscous composite. S4: spray drying the viscous composite at an air inlet temperature of 180° C. and an air outlet temperature of 80° C. 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: Dissolve 30 parts of polyepichlorohydrin-dimethylamine in 45 parts of deionized water at 40°C, add 15 parts of silica-coated magnetized attapulgite clay, and disperse the mixture at 300W ultrasonic wave for 20 minutes to obtain dispersion I. S2: Control the temperature to no higher than 25°C in an ice bath, add 35 parts of potassium persulfate to dispersion I, and react at this temperature for 2 hours to obtain a viscous composite. S3: spray drying the viscous composite at an air inlet temperature of 180° C. and an air outlet temperature of 80° C. to obtain a modifier for treating water-based drilling waste.

[0053] The modifiers prepared in the above embodiments and comparative examples were used to treat water-based drilling waste in the following manner: Under the condition of pH 3-4, a modifier is added to the water-based drilling waste, and the addition ratio of the modifier to the water-based drilling waste is 5 g / L; after reacting at 50° C. for 30 minutes, stirring at 40 rpm for 20 minutes, and centrifuging to obtain a filtrate and solid residue.

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

[0055] The filtrates obtained after modification with the modifiers in the above examples and comparative examples were evaluated according to GB / T 16783.1-2014 "Field testing of drilling fluids in the petroleum and natural gas industry - Part 1: Water-based drilling fluids".

[0056] The test results are shown in Table 1: Table 1

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

[0058] The data in Tables 1 and 2 demonstrate that the filtrate obtained by treating water-based drilling waste with the modifier provided by this application meets drilling fluid distribution requirements and can be directly reused without further extensive treatment. The modified cuttings are then converted into reduced soil, meeting the limits specified in the "Pollution Control Requirements for Comprehensive Utilization of Oil and Gas Field Drilling Solid Wastes" (DB 65 / T3997-1997). This reduced soil can be directly used for well road construction, well site paving, and pit filling.

[0059] The difference between Comparative Example 1 and Example 1 is that polyepichlorohydrin-dimethylamine was not added. Since effective flocculation could not be performed, 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 is not added, which cannot effectively catalyze potassium persulfate, and the lack of inorganic flocculant results in a significant reduction in the amount of flocs in the same flocculation time. Although the various performance data of the product are slightly better than those of Comparative Example 1, they are still significantly lower than those of Example 1 and cannot 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, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A modifier for treating water-based drilling waste, characterized in that: The raw materials include, by weight, 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.

2. The modifier for treating water-based drilling waste according to claim 1, characterized in that The quaternary ammonium cationic polymer is polyepichlorohydrin-dimethylamine.

3. The modifier for treating water-based drilling waste according to claim 2, characterized in that: The polyepichlorohydrin-dimethylamine was prepared as follows: At a temperature not higher than 5°C, epichlorohydrin is added dropwise to a dimethylamine aqueous solution, a catalyst is added, and the mixture is reacted at 40-60°C for 5-7 hours. The mixture is precipitated with acetone and vacuum dried to obtain polyepichlorohydrin-dimethylamine.

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

5. The modifier for treating water-based drilling waste according to claim 3, characterized in that: The catalyst is sodium hydroxide.

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

7. The modifier for treating water-based drilling waste according to any one of claims 1 to 6, characterized in that: The preparation method of the magnetized modified attapulgite clay comprises the following steps: S01: acidifying attapulgite clay with hydrochloric acid to obtain acid-activated attapulgite clay; S02: dispersing the acid-activated attapulgite clay in water, adding ferrous sulfate heptahydrate and ferric chloride hexahydrate in an inert gas atmosphere to obtain a reaction mixture I; S03: adding aqueous ammonia to the reaction mixture I until the pH reaches 10, reacting at 70-90° C., magnetic separation, ethanol washing, and drying to obtain magnetized modified attapulgite clay.

8. The modifier for treating water-based drilling waste according to claim 7, characterized in that: The preparation method of the magnetized modified attapulgite clay further comprises: S04: dispersing the magnetized modified attapulgite clay in a solvent, and adding ethyl orthosilicate to obtain a reaction mixture II; S05: adding aqueous ammonia to the reaction mixture II until the pH reaches 10, reacting at 40-60° C., and centrifugally drying to obtain silica-coated magnetized modified attapulgite clay.

9. The modifier for treating water-based drilling waste according to claim 8, characterized in that: The solvent in step S04 is a mixture of ethanol and water.

10. A method for preparing a modifier for treating water-based drilling waste according to any one of claims 1 to 9, characterized in that: The steps include: S1: Dissolving the quaternary ammonium cationic polymer in water according to the formula, and adding magnetized modified attapulgite clay to obtain dispersion I; S2: adding ferric chloride to the dispersion I and stirring to obtain dispersion II; S3: adding potassium persulfate to the dispersion II at a temperature not higher than 25° C. to react and obtain a viscous composite; S4: spray-drying the viscous composite to obtain a modifier for treating water-based drilling waste.

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