Crude oil demulsifier and preparation method thereof

Abstract

The invention belongs to the technical field of oil field demulsification, and particularly relates to a crude oil demulsifier and a preparation method thereof.The crude oil demulsifier is prepared from, by weight, 5-10 parts of a modified temperature-sensitive polymer, 0.25-1 part of a cross-linking agent, 0.2 part of a silane coupling agent and 0.1-0.2 part of TEA, the modified temperature-sensitive polymer based on NIPAM and hydrophobic graft is added, and the cross-linking agent is added to the modified temperature-sensitive polymer based on NIPAM and hydrophobic graft. The demulsifying efficiency of crude oil is improved through surface modified hydrophobic groups and interfacial active groups, hydrophilic-hydrophobic phase transformation is realized under temperature change, efficient separation of oil and water is realized, and the demulsifying agent material has a stable silica network structure, can be suitable for a high-salinity and high-viscosity complex emulsion environment, and has a wide application prospect. And the problem of difficulty in emulsion separation is solved by utilizing a dynamic interface regulation and control characteristic.

Description

Technical Field

[0001] The invention belongs to the technical field of oil field demulsification, and in particular relates to a crude oil demulsifier and a preparation method thereof. Background Art

[0002] The formation of oil-water emulsions is a common phenomenon in the process of crude oil extraction, transportation and processing. This type of emulsion is usually composed of crude oil, water and naturally existing or added surfactants, and exhibits high stability. The stability of the emulsion is mainly attributed to the stable interfacial film formed on the oil-water interface, which prevents the aggregation and separation of oil droplets. The presence of emulsions not only affects the processing efficiency of crude oil, but also increases equipment corrosion, energy consumption and operating costs, and even pollutes the environment.

[0003] At present, the demulsification technologies used in industry mainly include heating, centrifugation, ultrasonic treatment, addition of demulsifiers, and the use of electric and magnetic fields. Among them, chemical demulsifiers have become the main means of separating oil and water in crude oil because of their ease of use, high efficiency and wide adaptability. However, existing demulsifiers are difficult to maintain high efficiency and stability under high salinity, high temperature or complex oil products containing a large amount of colloid and asphalt emulsions; at the same time, some demulsifiers may cause secondary pollution to the environment after use, making it difficult to meet increasingly stringent environmental protection requirements. In addition, some demulsifiers have limited effects on the destruction of the oil-water interface film of the emulsion, resulting in the separation purity of the oil phase and the water phase unable to meet industrial needs. Current research is still focused on single responsive materials or simple interface regulation mechanisms, and it is difficult to take into account both adaptability and demulsification efficiency under complex emulsion conditions.

[0004] Therefore, the development of a new temperature-responsive demulsifier based on a dynamic interface regulation mechanism, which can accurately destroy the oil-water interface film under high temperature conditions and achieve efficient and environmentally friendly emulsion separation, has important research significance and industrial application value. Summary of the invention

[0005] In view of the above situation, the present invention provides a crude oil demulsifier and a preparation method thereof, which is a temperature-responsive demulsifier based on dynamic interface regulation, adopts NIPAM (N-isopropylacrylamide) as the core material, introduces hydrophobic groups and interfacial active groups on the polymer chain, enhances its oil-water interface adsorption and emulsion membrane destruction capabilities, and ultimately achieves efficient separation of oil and water in the process of crude oil refining and purification, and has the advantages of low dosage, green environmental protection and easy operation.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: The invention provides a crude oil demulsifier, which comprises the following raw materials in parts by weight: 5-10 parts of a modified temperature-sensitive polymer, 0.25-1 parts of a cross-linking agent, 0.2 parts of a silane coupling agent and 0.1-0.2 parts of TEA (triethylamine).

[0007] Furthermore, the modified thermosensitive polymer comprises the following raw materials in parts by weight: 5-10 parts of NIPAM, 0.5-1 parts of hydrophobic grafts, 0.1-0.3 parts of APS (ammonium persulfate) and 0.5-2 parts of dithiobenzoate.

[0008] Furthermore, the crosslinking agent is selected from any one of TEOS (tetraethyl orthosilicate), TBT (tetrabutyl titanate) and MTES (methyltriethoxysilane).

[0009] Furthermore, the silane coupling agent is selected from any one of KH560 (γ-glycidyloxypropyltrimethoxysilane), KH550 (γ-aminopropyltriethoxysilane) and KH590 (γ-mercaptopropyltrimethoxysilane).

[0010] Furthermore, the hydrophobic graft is selected from any one of n-octyl methacrylate, 4-methylstyrene and octadecyl acrylamide.

[0011] The preparation method of the modified thermosensitive polymer comprises the following steps: S1: Weigh 5-10 parts of NIPAM, 0.5-1 parts of hydrophobic grafts and 0.5-2 parts of dithiobenzoate and transfer them to a reaction bottle, then add methanol and stir and mix them. The mass volume ratio of NIPAM and methanol is 1 g:10 mL to obtain an initial solution; S2: Place the initial solution obtained in S1 in a magnetic stirrer, stir at 100 rpm until completely dissolved, introduce nitrogen for 20 min to remove oxygen from the solution, weigh 0.1-0.3 parts of APS, add it, and quickly seal the reaction bottle. Stir and react at 60°C and 100 rpm for 6 h to obtain a reaction solution; S3: adding deionized water to the reaction solution obtained in S2 to terminate the reaction, the volume ratio of deionized water to the methanol added in S1 is 0.5:10, to obtain a polymer solution, and slowly pouring the polymer solution into an excess of anhydrous ether to obtain a precipitate; S4: The precipitate obtained in S3 was centrifuged at 12000 rpm for 10 min, an equal amount of anhydrous ether was added to S3 for washing, and centrifuged to obtain a polymer precipitate. The polymer precipitate was vacuum dried at room temperature for 12 h at a vacuum degree of 130 Pa to obtain a modified thermosensitive polymer.

[0012] The present invention also provides a method for preparing a crude oil demulsifier, which specifically comprises the following steps: Step 1: Weigh 0.25-1 parts of a cross-linking agent and 0.2 parts of a silane coupling agent into a reaction bottle, add anhydrous ethanol into the reaction bottle, the mass volume ratio of the cross-linking agent to anhydrous ethanol is 1 g: 100 mL, then weigh 0.1-0.2 parts of TEA into the reaction bottle, stir at room temperature at 100 rpm for 30 min to dissolve, and obtain a transparent modified solution; Step 2: Weigh 5-10 parts of the modified thermosensitive polymer and add it to the transparent modified solution obtained in step 1, stir at 100 rpm for 5 min, and then ultrasonicate at 120 W for 20 min to obtain a dispersion; Step 3: under the conditions of 25°C and 100 rpm magnetic stirring, the dispersion obtained in step 2 is added dropwise into deionized water, the volume ratio of deionized water to the anhydrous ethanol in step 1 is 1:5. After the dropwise addition is completed, stirring is continued at 40°C for 1 h to obtain a hydrolysis condensation reaction liquid; Step 4: The hydrolysis condensation reaction liquid obtained in step 3 is subjected to rotary evaporation at 30° C. and 45 rpm to obtain a precipitate. The precipitate is washed 2-3 times with anhydrous ethanol and then vacuum dried at room temperature and 130 Pa for 4 h to obtain a crude oil demulsifier.

[0013] The beneficial effects achieved by the present invention are as follows: The crude oil demulsifier prepared by the present invention can realize hydrophilic-hydrophobic phase transition under temperature change based on the temperature response characteristics of NIPAM-based polymers, and dynamically destroy the stable film of the oil-water interface in the crude oil emulsion; the synergistic effect of the crosslinking agent and the silane coupling agent constructs a stable silicon-oxygen network structure, improves the chemical stability of the material, and the introduced hydrophobic group further enhances the interface adsorption capacity and selectivity of the material, so that the material exhibits excellent oil-water separation effect in a complex emulsion environment with high salinity and high viscosity, can effectively solve the problem of difficult emulsion separation, has dynamic interface regulation ability, and improves the residual problem of the water layer after demulsification, is suitable for complex working conditions under high temperature and high pressure conditions, has stronger adsorption capacity for oil droplets in complex emulsions, is simple to prepare, has strong adaptability, and has high demulsification efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The process flow chart of the crude oil demulsifier prepared by the present invention; Figure 2 The demulsification efficiency test results of the crude oil demulsifiers prepared in Examples 1-5; Figure 3 Zeta potential test results of the crude oil demulsifier prepared in Example 1 under different pH conditions; Figure 4 These are the viscoelastic modulus test results of the crude oil demulsifiers prepared in Examples 1-5. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0016] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and are not intended to limit the content of this application.

[0017] In the following embodiments, the preparation process of the crude oil demulsifier is as follows: Figure 1 As shown, unless otherwise specified, all methods are conventional; the materials used in the following embodiments, unless otherwise specified, are new materials purchased from the market.

[0018] Example 1: This example provides a crude oil demulsifier, which includes the following raw materials in parts by weight: 8 parts of modified temperature-sensitive polymer, 0.4 parts of TEOS, 0.2 parts of KH560 and 0.15 parts of TEA.

[0019] The modified thermosensitive polymer comprises the following raw materials in parts by weight: 5 parts of NIPAM, 0.5 parts of n-octyl methacrylate, 0.2 parts of APS and 1 part of dithiobenzoate; The preparation method of the modified thermosensitive polymer comprises the following steps: S1: Weigh 5 parts of NIPAM, 0.5 parts of n-octyl methacrylate and 1 part of dithiobenzoate and transfer them to a reaction bottle, then add methanol and stir and mix them. The mass volume ratio of NIPAM and methanol is 1 g:10 mL to obtain an initial solution; S2: Place the initial solution obtained in S1 in a magnetic stirrer, stir at 100 rpm until completely dissolved, introduce nitrogen for 20 min to remove oxygen from the solution, weigh 0.2 parts of APS and add it into the reaction bottle, quickly seal the reaction bottle, stir at 60°C and 100 rpm for 6 h to obtain a reaction solution; S3: adding deionized water to the reaction solution obtained in S2 to terminate the reaction, the volume ratio of deionized water to the methanol added in S1 is 0.5:10, to obtain a polymer solution, and slowly pouring the polymer solution into an excess of anhydrous ether to obtain a precipitate; S4: The precipitate obtained in S3 was centrifuged at 12000 rpm for 10 min, an equal amount of anhydrous ether was added to S3 for washing, and the mixture was centrifuged to obtain a polymer precipitate. The polymer precipitate was vacuum dried at room temperature for 12 h at a vacuum degree of 130 Pa to obtain a modified thermosensitive polymer.

[0020] This embodiment also provides a method for preparing a crude oil demulsifier, which specifically comprises the following steps: Step 1: Weigh 0.4 parts of TEOS and 0.2 parts of KH560 into a reaction bottle, add anhydrous ethanol into the reaction bottle, the mass volume ratio of TEOS and anhydrous ethanol is 1 g: 100 mL, then weigh 0.15 parts of TEA into the reaction bottle, stir at room temperature at 100 rpm for 30 min to dissolve, and obtain a transparent modified solution; Step 2: Weigh 8 parts of the modified thermosensitive polymer and add them to the transparent modified solution obtained in step 1, stir at 100 rpm for 5 min, and then ultrasonicate at 120 W for 20 min to obtain a dispersion; Step 3: under the conditions of 25°C and 100 rpm magnetic stirring, the dispersion obtained in step 2 is added dropwise into deionized water, the volume ratio of deionized water to the anhydrous ethanol in step 1 is 1:5. After the dropwise addition is completed, stirring is continued at 40°C for 1 h to obtain a hydrolysis condensation reaction liquid; Step 4: The hydrolysis condensation reaction liquid obtained in step 3 was subjected to rotary evaporation at 30°C and 45 rpm to obtain a precipitate. The precipitate was washed with anhydrous ethanol for 3 times and then vacuum dried at room temperature and 130 Pa for 4 h to obtain a crude oil demulsifier.

[0021] Example 2: This example provides a crude oil demulsifier, which includes the following raw materials in parts by weight: 5 parts of modified temperature-sensitive polymer, 0.25 parts of TBT, 0.2 parts of KH550 and 0.1 parts of TEA.

[0022] The modified thermosensitive polymer comprises the following raw materials in parts by weight: 8 parts of NIPAM, 0.8 parts of n-octyl methacrylate, 0.1 parts of APS and 0.5 parts of dithiobenzoate; The preparation method of the modified thermosensitive polymer comprises the following steps: S1: Weigh 8 parts of NIPAM, 0.8 parts of n-octyl methacrylate and 0.5 parts of dithiobenzoate and transfer them to a reaction bottle, then add methanol and stir and mix them. The mass volume ratio of NIPAM and methanol is 1 g:10 mL to obtain an initial solution; S2: Place the initial solution obtained in S1 in a magnetic stirrer, stir at 100 rpm until completely dissolved, introduce nitrogen for 20 min to remove oxygen from the solution, weigh 0.1 parts of APS and add it into the reaction bottle, quickly seal the reaction bottle, stir at 60°C and 100 rpm for 6 h to obtain a reaction solution; S3: adding deionized water to the reaction solution obtained in S2 to terminate the reaction, the volume ratio of deionized water to the methanol added in S1 is 0.5:10, to obtain a polymer solution, and slowly pouring the polymer solution into an excess of anhydrous ether to obtain a precipitate; S4: The precipitate obtained in S3 was centrifuged at 12000 rpm for 10 min, an equal amount of anhydrous ether was added to S3 for washing, and the mixture was centrifuged to obtain a polymer precipitate. The polymer precipitate was vacuum dried at room temperature for 12 h at a vacuum degree of 130 Pa to obtain a modified thermosensitive polymer.

[0023] This embodiment also provides a method for preparing a crude oil demulsifier, which specifically comprises the following steps: Step 1: Weigh 0.25 parts of TBT and 0.2 parts of KH550 into a reaction bottle, add anhydrous ethanol into the reaction bottle, the mass volume ratio of TBT to anhydrous ethanol is 1 g: 100 mL, then weigh 0.1 parts of TEA into the reaction bottle, stir at room temperature at 100 rpm for 30 minutes to dissolve, and obtain a transparent modified solution; Step 2: Weigh 5 parts of the modified thermosensitive polymer and add them to the transparent modified solution obtained in step 1, stir at 100 rpm for 5 min, and then ultrasonicate at 120 W for 20 min to obtain a dispersion; Step 3: under the conditions of 25°C and 100 rpm magnetic stirring, the dispersion obtained in step 2 is added dropwise into deionized water, the volume ratio of deionized water to the anhydrous ethanol in step 1 is 1:5. After the dropwise addition is completed, stirring is continued at 40°C for 1 h to obtain a hydrolysis condensation reaction liquid; Step 4: The hydrolysis condensation reaction solution obtained in step 3 was subjected to rotary evaporation at 30° C. and 45 rpm to obtain a precipitate. The precipitate was washed twice with anhydrous ethanol and then vacuum dried at room temperature and 130 Pa for 4 h to obtain a crude oil demulsifier.

[0024] Example 3: This example provides a crude oil demulsifier, which includes the following raw materials in parts by weight: 10 parts of modified temperature-sensitive polymer, 1 part of MTES, 0.2 parts of KH590 and 0.2 parts of TEA.

[0025] The modified thermosensitive polymer comprises the following raw materials in parts by weight: 10 parts of NIPAM, 1 part of n-octyl methacrylate, 0.3 parts of APS and 2 parts of dithiobenzoate; The preparation method of the modified thermosensitive polymer comprises the following steps: S1: Weigh 10 parts of NIPAM, 1 part of n-octyl methacrylate and 2 parts of dithiobenzoate and transfer them to a reaction bottle, then add methanol and stir and mix them. The mass volume ratio of NIPAM and methanol is 1 g:10 mL to obtain an initial solution; S2: Place the initial solution obtained in S1 in a magnetic stirrer, stir at 100 rpm until completely dissolved, introduce nitrogen for 20 min to remove oxygen from the solution, weigh 0.3 parts of APS and add it into the reaction bottle, quickly seal the reaction bottle, stir at 60°C and 100 rpm for 6 h to obtain a reaction solution; S3: adding deionized water to the reaction solution obtained in S2 to terminate the reaction, the volume ratio of deionized water to the methanol added in S1 is 0.5:10, to obtain a polymer solution, and slowly pouring the polymer solution into an excess of anhydrous ether to obtain a precipitate; S4: The precipitate obtained in S3 was centrifuged at 12000 rpm for 10 min, an equal amount of anhydrous ether was added to S3 for washing, and the mixture was centrifuged to obtain a polymer precipitate. The polymer precipitate was vacuum dried at room temperature for 12 h at a vacuum degree of 130 Pa to obtain a modified thermosensitive polymer.

[0026] This embodiment also provides a method for preparing a crude oil demulsifier, which specifically comprises the following steps: Step 1: Weigh 1 part of MTES and 0.2 parts of KH590 in a reaction bottle, add anhydrous ethanol to the reaction bottle, the mass volume ratio of MTES and anhydrous ethanol is 1 g: 100 mL, then weigh 0.2 parts of TEA and add it to the reaction bottle, stir at room temperature at 100 rpm for 30 minutes to dissolve, and obtain a transparent modified solution; Step 2: Weigh 10 parts of the modified thermosensitive polymer and add them to the transparent modified solution obtained in step 1, stir at 100 rpm for 5 min, and then ultrasonicate at 120 W for 20 min to obtain a dispersion; Step 3: under the conditions of 25°C and 100 rpm magnetic stirring, the dispersion obtained in step 2 is added dropwise into deionized water, the volume ratio of deionized water to the anhydrous ethanol in step 1 is 1:5. After the dropwise addition is completed, stirring is continued at 40°C for 1 h to obtain a hydrolysis condensation reaction liquid; Step 4: The hydrolysis condensation reaction solution obtained in step 3 was subjected to rotary evaporation at 30° C. and 45 rpm to obtain a precipitate. The precipitate was washed twice with anhydrous ethanol and then vacuum dried at room temperature and 130 Pa for 4 h to obtain a crude oil demulsifier.

[0027] Example 4: This example provides a crude oil demulsifier, which includes the following raw materials in parts by weight: 8 parts of modified temperature-sensitive polymer, 0.4 parts of TEOS, 0.2 parts of KH560 and 0.15 parts of TEA.

[0028] The modified thermosensitive polymer comprises the following raw materials in parts by weight: 5 parts of NIPAM, 0.5 parts of 4-methylstyrene, 0.2 parts of APS and 1 part of dithiobenzoate; The preparation method of the modified thermosensitive polymer comprises the following steps: S1: Weigh 5 parts of NIPAM, 0.5 parts of 4-methylstyrene and 1 part of dithiobenzoate and transfer them to a reaction bottle, then add methanol and stir and mix them. The mass volume ratio of NIPAM and methanol is 1 g:10 mL to obtain an initial solution; S2: Place the initial solution obtained in S1 in a magnetic stirrer, stir at 100 rpm until completely dissolved, introduce nitrogen for 20 min to remove oxygen from the solution, weigh 0.2 parts of APS and add it into the reaction bottle, quickly seal the reaction bottle, stir at 60°C and 100 rpm for 6 h to obtain a reaction solution; S3: adding deionized water to the reaction solution obtained in S2 to terminate the reaction, the volume ratio of deionized water to the methanol added in S1 is 0.5:10, to obtain a polymer solution, and slowly pouring the polymer solution into an excess of anhydrous ether to obtain a precipitate; S4: The precipitate obtained in S3 was centrifuged at 12000 rpm for 10 min, an equal amount of anhydrous ether was added to S3 for washing, and the mixture was centrifuged to obtain a polymer precipitate. The polymer precipitate was vacuum dried at room temperature for 12 h at a vacuum degree of 130 Pa to obtain a modified thermosensitive polymer.

[0029] This embodiment also provides a method for preparing a crude oil demulsifier, which specifically comprises the following steps: Step 1: Weigh 0.4 parts of TEOS and 0.2 parts of KH560 into a reaction bottle, add anhydrous ethanol into the reaction bottle, the mass volume ratio of TEOS and anhydrous ethanol is 1 g: 100 mL, then weigh 0.15 parts of TEA into the reaction bottle, stir at room temperature at 100 rpm for 30 min to dissolve, and obtain a transparent modified solution; Step 2: Weigh 8 parts of the modified thermosensitive polymer and add them to the transparent modified solution obtained in step 1, stir at 100 rpm for 5 min, and then ultrasonicate at 120 W for 20 min to obtain a dispersion; Step 3: under the conditions of 25°C and 100 rpm magnetic stirring, the dispersion obtained in step 2 is added dropwise into deionized water, the volume ratio of deionized water to the anhydrous ethanol in step 1 is 1:5. After the dropwise addition is completed, stirring is continued at 40°C for 1 h to obtain a hydrolysis condensation reaction liquid; Step 4: The hydrolysis condensation reaction liquid obtained in step 3 was subjected to rotary evaporation at 30°C and 45 rpm to obtain a precipitate. The precipitate was washed with anhydrous ethanol for 3 times and then vacuum dried at room temperature and 130 Pa for 4 h to obtain a crude oil demulsifier.

[0030] Example 5: This example provides a crude oil demulsifier, which includes the following raw materials in parts by weight: 8 parts of modified temperature-sensitive polymer, 0.4 parts of TEOS, 0.2 parts of KH560 and 0.15 parts of TEA.

[0031] The modified thermosensitive polymer comprises the following raw materials in parts by weight: 5 parts of NIPAM, 0.5 parts of octadecyl acrylamide, 0.2 parts of APS and 1 part of dithiobenzoate; The preparation method of the modified thermosensitive polymer comprises the following steps: S1: Weigh 5 parts of NIPAM, 0.5 parts of octadecyl acrylamide and 1 part of dithiobenzoate and transfer them to a reaction bottle, then add methanol and stir and mix them. The mass volume ratio of NIPAM and methanol is 1 g:10 mL to obtain an initial solution; S2: Place the initial solution obtained in S1 in a magnetic stirrer, stir at 100 rpm until completely dissolved, introduce nitrogen for 20 min to remove oxygen from the solution, weigh 0.2 parts of APS and add it into the reaction bottle, quickly seal the reaction bottle, stir at 60°C and 100 rpm for 6 h to obtain a reaction solution; S3: adding deionized water to the reaction solution obtained in S2 to terminate the reaction, the volume ratio of deionized water to the methanol added in S1 is 0.5:10, to obtain a polymer solution, and slowly pouring the polymer solution into an excess of anhydrous ether to obtain a precipitate; S4: The precipitate obtained in S3 was centrifuged at 12000 rpm for 10 min, an equal amount of anhydrous ether was added to S3 for washing, and the mixture was centrifuged to obtain a polymer precipitate. The polymer precipitate was vacuum dried at room temperature for 12 h at a vacuum degree of 130 Pa to obtain a modified thermosensitive polymer.

[0032] This embodiment also provides a method for preparing a crude oil demulsifier, which specifically comprises the following steps: Step 1: Weigh 0.4 parts of TEOS and 0.2 parts of KH560 into a reaction bottle, add anhydrous ethanol into the reaction bottle, the mass volume ratio of TEOS and anhydrous ethanol is 1 g: 100 mL, then weigh 0.15 parts of TEA into the reaction bottle, stir at room temperature at 100 rpm for 30 min to dissolve, and obtain a transparent modified solution; Step 2: Weigh 8 parts of the modified thermosensitive polymer and add them to the transparent modified solution obtained in step 1, stir at 100 rpm for 5 min, and then ultrasonicate at 120 W for 20 min to obtain a dispersion; Step 3: under the conditions of 25°C and 100 rpm magnetic stirring, the dispersion obtained in step 2 is added dropwise into deionized water, the volume ratio of deionized water to the anhydrous ethanol in step 1 is 1:5. After the dropwise addition is completed, stirring is continued at 40°C for 1 h to obtain a hydrolysis condensation reaction liquid; Step 4: The hydrolysis condensation reaction liquid obtained in step 3 was subjected to rotary evaporation at 30°C and 45 rpm to obtain a precipitate. The precipitate was washed with anhydrous ethanol for 3 times and then vacuum dried at room temperature and 130 Pa for 4 h to obtain a crude oil demulsifier.

[0033] Preparation of W / O emulsion Weigh 300 g crude oil and 700 g deionized water, stir and mix, place in a 70°C constant temperature water bath for 30 min, and emulsify at 10,000 rpm using a high shear homogenizer for 20 min to obtain a W / O emulsion for use.

[0034] Crude oil properties The physicochemical properties of crude oil used for the performance test of the crude oil demulsifiers prepared in Examples 1-5 are shown in Table 1.

[0035] Table 1 Physical and chemical properties of crude oil

[0036] Demulsification performance test The demulsification performance of the crude oil demulsifier prepared in Examples 1-5 was determined by the bottle test method. 50 mg of the crude oil demulsifier prepared in Examples 1-5 was weighed and dissolved in 5 mL of deionized water to prepare a demulsifier solution, which was added to 95 mL of the W / O emulsion prepared above. After vigorous shaking for 5 min, the demulsification capacity at 0, 10, 15, 30, 60, 120 and 180 min was recorded in a 60°C water bath. Only an equal volume of deionized water was added as a blank control, and the demulsification efficiency (DE) was calculated according to the following formula: Demulsification efficiency (DE) % = V / V0 × 100%; wherein V and V0 are the volume of the separated aqueous phase and the volume of water contained in the original emulsion, respectively. The results are shown in Figure 2 .

[0037] Zeta potential measurement The crude oil demulsifier prepared in Example 1 was dissolved in deionized water to prepare a 1 mg / mL demulsifier solution. The pH of the demulsifier solution was adjusted to 2.0, 4.0, 6.0, 7.0, 8.0, 10.0 and 12.0 with 1 mol / L hydrochloric acid solution and 1 mol / L sodium hydroxide solution, respectively. The Zeta potential at the corresponding pH value was measured using a nanoparticle size analyzer. The results are shown in Table 1. Figure 3 .

[0038] Viscoelastic modulus investigation The viscoelastic modulus of the interfacial film was measured using an interfacial rheometer. The crude oil demulsifiers prepared in Examples 1-5 were weighed and added to xylene to prepare a demulsifier solution with a concentration of 5 μg / mL as the oil phase, purified water as the water phase, and xylene without demulsifier as the blank control. Each group was repeated 3 times, and the average value was calculated. The viscoelastic modulus test results are shown in Figure 4 .

[0039] Figure 2 The results show that the crude oil demulsifiers prepared in Examples 1-5 all have good demulsification capabilities, with an emulsification efficiency of 94% within 180 min, and the demulsification efficiencies of Examples 3 and 5 are above 80% at 30 min.

[0040] Figure 3 The results showed that with the increase of pH value, the Zeta potential of the demulsifier aqueous solution prepared in Example 1 decreased from 25.9 mV to 12.5 mV, indicating that the demulsifier underwent protonation reaction in the acidic solution, which increased the positive charge of the demulsifier ions, was beneficial to charge neutralization, and thus improved the demulsification effect.

[0041] Figure 4 The viscoelastic modulus results show that the crude oil demulsifiers prepared in Examples 1-5 can effectively reduce the strength of the interfacial film, which is beneficial to promote the rupture of the interfacial film and thus promote the demulsification process.

[0042] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0043] The present invention and its implementation methods are described above, which is not restrictive. The drawings are only one of the implementation methods of the present invention, and the actual application is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A crude oil demulsifier, characterized in that: The crude oil demulsifier comprises the following raw materials in parts by weight: 5-10 parts of modified temperature-sensitive polymer, 0.25-1 parts of cross-linking agent, 0.2 parts of silane coupling agent and 0.1-0.2 parts of TEA; The modified thermosensitive polymer comprises the following raw materials in parts by weight: 5-10 parts of NIPAM, 0.5-1 parts of hydrophobic grafts, 0.1-0.3 parts of APS and 0.5-2 parts of dithiobenzoate. The specific preparation process of the modified thermosensitive polymer comprises the following steps: S1: Weigh NIPAM, hydrophobic graft and dithiobenzoate, add solvent and mix well to obtain an initial solution; S2: remove oxygen from the initial solution, weigh APS, add it into the initial solution and seal the reaction to obtain a reaction solution; S3: terminating the reaction, obtaining a polymer solution and transferring it into anhydrous ether to obtain a precipitate; S4: Centrifuge, wash and dry the precipitate obtained in S3 to obtain a modified thermosensitive polymer.

2. A crude oil demulsifier according to claim 1, characterized in that: In step S1, the mass volume ratio of NIPAM to solvent is 1 g:10 mL, in step S2, the method of removing oxygen is to introduce nitrogen, and in step S3, the operation of terminating the reaction is to add deionized water to the reaction solution obtained in step S2 to terminate the polymerization process.

3. A crude oil demulsifier according to claim 1, characterized in that: The cross-linking agent is selected from any one of TEOS, TBT and MTES.

4. A crude oil demulsifier according to claim 1, characterized in that: The silane coupling agent is selected from any one of KH560, KH550 and KH590.

5. A crude oil demulsifier according to claim 1, characterized in that: The hydrophobic graft is selected from any one of n-octyl methacrylate, 4-methylstyrene and octadecyl acrylamide.

6. A method for preparing a crude oil demulsifier according to any one of claims 1 to 5, characterized in that: The specific steps include: Step 1: weigh a crosslinking agent and a silane coupling agent, add anhydrous ethanol and TEA, mix and dissolve to obtain a transparent modified solution; Step 2: Weigh the modified thermosensitive polymer and add it to the transparent modified solution obtained in step 1, stir and sonicate to obtain a dispersion; Step 3: dropping the dispersion obtained in step 2 into deionized water and stirring to obtain a hydrolysis condensation reaction solution; Step 4: Rotary evaporate the hydrolysis condensation reaction liquid obtained in step 3 to obtain a precipitate, wash and dry the precipitate to obtain a crude oil demulsifier.

7. The method for preparing a crude oil demulsifier according to claim 6, characterized in that: In step 1, the mass volume ratio of the cross-linking agent to anhydrous ethanol is 1 g:100 mL. In step 3, the volume ratio of the deionized water to the anhydrous ethanol in step 1 is 1:5.

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