Demulsifier as well as preparation method and application thereof

Abstract

The invention provides a demulsifier as well as a preparation method and application thereof, and belongs to the technical field of demulsifiers. The demulsifying agent provided by the invention comprises the following components: modified nano silicon dioxide, a nonionic polyether demulsifying agent and a solvent, the modified nano silicon dioxide is nano silicon dioxide modified by adopting a silane coupling agent and a cationic surface active agent. The synergistic effect of the modified nano silicon dioxide and the non-ionic polyether demulsifier can more quickly destroy an oil-water interfacial film, destroy the stability of the emulsion and reduce the viscosity of crude oil, and dispersed small water drops can spontaneously gather and settle under the action of gravity, so that the demulsifying oil-water separation effect is achieved; the demulsifier has moderate low interfacial tension and strong interfacial activity, and has excellent viscosity reduction capability and demulsification effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of demulsifiers, and particularly relates to a demulsifier, a preparation method thereof, and an application thereof. Background Art

[0002] At present, the oilfield has entered the high water cut period, and the crude oil emulsion has changed from CDE type to EDC type, which increases the difficulty of demulsifying and dehydrating crude oil. While meeting the needs of the oilfield and ensuring the demulsifying and dehydrating effect of crude oil, it has also greatly promoted the R & D process of crude oil demulsifiers. Traditional demulsifiers usually include polyethers, silica gels, ionic liquids, and natural polymers, but the demulsifying effect of these demulsifiers is poor and cannot meet the demulsifying requirements of heavy oil. Summary of the Invention

[0003] The purpose of the present invention is to provide a demulsifier, a preparation method thereof, and an application thereof. The demulsifier provided by the present invention has excellent demulsifying effect.

[0004] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a demulsifier, which comprises the following components: modified nano-silica, non-ionic polyether demulsifier, and solvent;

[0006] The modified nano-silica is nano-silica modified by a silane coupling agent and a cationic surfactant.

[0007] Preferably, the mass ratio of the modified nano-silica to the non-ionic polyether demulsifier is 1:(5 - 20).

[0008] Preferably, the preparation method of the modified nano-silica comprises the following steps:

[0009] (1) Mix nano-silica modified by a silane coupling agent, an inorganic solvent, a first stabilizer, and a cationic surfactant to obtain a suspension;

[0010] (2) Mix the suspension obtained in the step (1), a second stabilizer, and an organic solvent for modification to obtain modified nano-silica.

[0011] Preferably, the first stabilizer in the step (1) includes triethanolamine.

[0012] Preferably, the mass ratio of the nano-silica modified by a silane coupling agent to the first stabilizer in the step (1) is (1 - 1.5):(3 - 3.5).

[0013] Preferably, the cationic surfactant in the step (1) includes cetyltrimethylammonium chloride.

[0014] Preferably, the mass ratio of the silane coupling agent - modified nano - silica to the cationic surfactant in step (1) is (1 - 3):7.

[0015] Preferably, the second stabilizer in step (2) includes urea.

[0016] The present invention also provides a preparation method of the demulsifier described in the above - mentioned technical solution, including:

[0017] Mix the modified nano - silica, non - ionic polyether demulsifier and solvent to obtain the demulsifier.

[0018] The present invention also provides the application of the demulsifier described in the above - mentioned technical solution or the demulsifier prepared by the preparation method described in the above - mentioned technical solution in water - containing heavy oil.

[0019] The present invention provides a demulsifier, which comprises the following components: modified nano - silica, non - ionic polyether demulsifier and solvent; the modified nano - silica is nano - silica modified by a silane coupling agent and a cationic surfactant. In the present invention, the modified nano - silica is modified by a cationic surfactant, which makes the system have high surface activity and strong permeability, and can neutralize and offset the emulsifier, destroying the stability of the emulsion interfacial film; at the same time, the nano - silica modified by a silane coupling agent can increase the surface active components, and the surface active components will also chemically react with asphaltene and resin; the hydrophilic group (ether bond) of the non - ionic polyether demulsifier makes it easier to form hydrogen bonds with water molecules than asphaltene, destroying the asphaltene interfacial film; the synergistic effect of the modified nano - silica and the non - ionic polyether demulsifier can more quickly destroy the oil - water interfacial film, destroy the stability of the emulsion, reduce the viscosity of crude oil, and the dispersed small water droplets can spontaneously aggregate and settle under the action of gravity, so as to achieve the effect of demulsifying oil - water separation, making the demulsifier have moderate low interfacial tension and strong interfacial activity, and excellent viscosity - reducing ability and demulsification effect. The experimental results show that the viscosity - reducing rate of the demulsifier provided by the present invention is 93.3 - 98.7%, and the demulsification rate at 30 min is 95.3 - 98.2%. Detailed implementation manners

[0020] The present invention provides a demulsifier, which comprises the following components: modified nano - silica, non - ionic polyether demulsifier and solvent;

[0021] The modified nano - silica is nano - silica modified by a silane coupling agent and a cationic surfactant.

[0022] The present invention has no special limitation on the sources of each raw material, and commercially available products well - known to those skilled in the art can be used.

[0023] The components of the demulsifier provided by the present invention include modified nano-silica; the modified nano-silica is nano-silica modified with a silane coupling agent and a cationic surfactant. In the present invention, the modified nano-silica is modified with a cationic surfactant, making the system have high surface activity and strong permeability, capable of neutralizing and offsetting with the emulsifier, and destroying the stability of the emulsion interfacial film; at the same time, the active components on the surface of the nano-silica will also undergo chemical reactions with asphaltene and resin.

[0024] In the present invention, the particle size of the modified nano-silica is preferably 1 - 100 nm. In the present invention, the modified nano-silica has high modifiability and high activity, greatly promoting the efficient demulsification of crude oil.

[0025] In the present invention, the preparation method of the modified nano-silica preferably includes the following steps:

[0026] (1) Mix nano-silica modified with a silane coupling agent, an inorganic solvent, a first stabilizer, and a cationic surfactant to obtain a suspension;

[0027] (2) Mix the suspension obtained in step (1) with a second stabilizer and an organic solvent for modification to obtain modified nano-silica.

[0028] The present invention preferably mixes nano-silica modified with a silane coupling agent, an inorganic solvent, a first stabilizer, and a cationic surfactant to obtain a suspension.

[0029] In the present invention, the lateral dimension of the nano-silica is preferably 20 - 50 nm; the thickness of the nano-silica is preferably 5 - 10 nm.

[0030] In the present invention, the preparation method of the nano-silica preferably includes the following steps:

[0031] 1) Mix an oil phase, a non-ionic surfactant, an aqueous phase, ethanol, and a pH regulator to obtain a reverse microemulsion;

[0032] 2) Mix the reverse microemulsion obtained in step 1) with tetrabutyl titanate, and then perform centrifugation and filtration in sequence to obtain a gel;

[0033] 3) Dry and calcine the gel obtained in step 2) in sequence to obtain nano-silica.

[0034] The present invention preferably mixes an oil phase, a non-ionic surfactant, an aqueous phase, ethanol, and a pH regulator to obtain a reverse microemulsion.

[0035] In the present invention, the oil phase is preferably n-hexane; the nonionic surfactant is preferably nonylphenol polyoxyethylene ether; the aqueous phase is preferably ultrapure water; the volume ratio of the oil phase, nonionic surfactant and aqueous phase is preferably (20-25):(5-7):(3-5). The present invention uses a nonionic surfactant to modify nano-silica and improve its hydrophilicity.

[0036] As an embodiment, the volume ratio of the oil phase, nonionic surfactant and aqueous phase can be (21-24):(6-7):(4-5), or can also be (22-23):(6-7):(4-5).

[0037] In the present invention, the pH regulator is preferably concentrated ammonia water. The present invention has no special limitation on the concentration of the concentrated ammonia water, as long as the pH value of the adjusted solution is within the range of 10-12.

[0038] In the present invention, the mixing of the oil phase, nonionic surfactant, aqueous phase, ethanol and pH regulator is preferably to mix the oil phase, nonionic surfactant and aqueous phase, then dropwise add ethanol, and then add the pH regulator.

[0039] In the present invention, the temperature for mixing the oil phase, nonionic surfactant and aqueous phase is preferably 35-50 °C. The present invention has no special limitation on the mixing time, and it is sufficient to mix evenly.

[0040] The present invention has no special limitation on the dropping rate of the ethanol, and a dropping rate well-known to those skilled in the art can be used. The present invention has no special limitation on the amount of the ethanol used, and it is sufficient to drop until the solution is no longer turbid.

[0041] In the present invention, the pH regulator is preferably added under stirring conditions; the stirring time is preferably 0.5-2 h. The present invention has no special limitation on the stirring rate, as long as the raw materials are completely dissolved.

[0042] As an embodiment, the stirring time can be 0.8 h.

[0043] After obtaining the reverse microemulsion, the present invention preferably mixes the reverse microemulsion and tetrabutyl titanate, and then performs centrifugation and filtration in sequence to obtain a gel.

[0044] In the present invention, the mass ratio of the reverse microemulsion and tetrabutyl titanate is preferably (1-3):1, more preferably 3:1; the mixing of the reverse microemulsion and tetrabutyl titanate is preferably carried out under stirring conditions; the stirring time is preferably 1-4 h. As an embodiment, the stirring time can be 2.5 h. The present invention has no special limitation on the stirring rate, as long as the raw materials are completely dissolved.

[0045] The present invention has no special limitation on the centrifugation operation, and the operations well-known to those skilled in the art can be adopted.

[0046] The present invention has no special limitation on the filtration operation, and the supernatant can be removed.

[0047] After the filtration is completed, the present invention preferably washes the product obtained by filtration to obtain a gel.

[0048] In the present invention, the detergent used for the washing is preferably acetone and ethanol; the volume ratio of the acetone to the ethanol is (1-2):(1-2). The present invention has no special limitation on the dosage of the detergent, and it is only necessary to wash the product obtained by filtration clean.

[0049] After obtaining the gel, the present invention preferably dries and calcines the gel in sequence to obtain nano-silica.

[0050] In the present invention, the temperature for the drying is preferably 110-130°C; the time for the drying is preferably 3-5 h, more preferably 4 h. As an embodiment, the temperature for the drying can be 115-125°C, and can also be 120°C.

[0051] In the present invention, the temperature for the calcination is preferably 400-600°C; the time for the calcination is preferably 2-5 h. As an embodiment, the temperature for the calcination can be 500°C; the time for the calcination can be 3-4 h.

[0052] The present invention uses the reverse microemulsion method to prepare nano-silica, which can precisely control the size, morphology and structure of nano-particles at the microscale.

[0053] In the present invention, the preparation method of the nano-silica modified by a silane coupling agent preferably comprises the following steps:

[0054] ① Mix a first solvent and a silane coupling agent to obtain a silane coupling agent solution;

[0055] ② Mix a second solvent and the nano-silica to obtain a nano-silica dispersion;

[0056] ③ Mix the silane coupling agent solution obtained in the step ① and the nano-silica dispersion obtained in the step ②, and carry out modification to obtain the nano-silica modified by a silane coupling agent;

[0057] There is no sequence priority between the step ① and the step ②.

[0058] The present invention preferably mixes a first solvent and a silane coupling agent to obtain a silane coupling agent solution.

[0059] In the present invention, the first solvent is preferably deionized water.

[0060] In the present invention, the silane coupling agent is preferably vinyltrimethoxysilane.

[0061] The present invention has no special limitation on the operation of mixing the first solvent and the silane coupling agent, and a technical solution for preparing a mixed material well-known to those skilled in the art can be adopted.

[0062] In the present invention, the concentration of the silane coupling agent solution is preferably 0.1 - 1 wt%. As an embodiment, the concentration of the silane coupling agent solution can be 0.2 - 0.8 wt%, and can also be 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt% or 0.7 wt%.

[0063] The present invention preferably mixes a second solvent and nano-silica to obtain a nano-silica dispersion.

[0064] In the present invention, the second solvent is preferably deionized water.

[0065] The present invention has no special limitation on the operation of mixing the second solvent and nano-silica, and a technical solution for preparing a mixed material well-known to those skilled in the art can be adopted.

[0066] In the present invention, the concentration of the nano-silica dispersion is preferably 1 - 10 wt%. As an embodiment, the concentration of the nano-silica dispersion can be 2 - 9 wt%, and can also be 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt% or 8 wt%.

[0067] After obtaining the silane coupling agent solution and the nano-silica dispersion, the present invention preferably mixes the silane coupling agent solution and the nano-silica dispersion for modification to obtain silane coupling agent-modified nano-silica.

[0068] In the present invention, the volume ratio of the silane coupling agent solution to the nano-silica dispersion is preferably (1 - 2) : (1 - 2). Limiting the volume ratio of the silane coupling agent solution to the nano-silica dispersion within the above range in the present invention can improve the modification effect.

[0069] The present invention has no special limitation on the operation of mixing the silane coupling agent solution and the nano-silica dispersion, and a technical solution for preparing a mixed material well-known to those skilled in the art can be adopted.

[0070] In the present invention, the temperature of the modification is preferably 50 - 70°C, more preferably 60°C; the time of the modification is preferably 11 - 13 h, more preferably 12 h; the modification is preferably carried out under stirring conditions; the stirring rate is preferably 200 - 400 rpm, more preferably 300 rpm. Limiting the process parameters of the modification within the above ranges in the present invention can improve the modification effect.

[0071] After the modification is completed, the present invention preferably cools, filters, washes, and dries the product obtained by the modification to obtain silane coupling agent-modified nano-silica.

[0072] The present invention has no special limitation on the operation of the cooling, and it can be cooled to room temperature.

[0073] The present invention has no special limitation on the operation of the filtration, and the filter residue can be obtained by using the operations well-known to those skilled in the art.

[0074] The present invention has no special limitation on the operation of the washing, and the impurities can be removed.

[0075] The present invention has no special limitation on the operation of the drying, and it can be dried to a constant weight.

[0076] In the present invention, the inorganic solvent is preferably deionized water.

[0077] In the present invention, the first stabilizer preferably includes triethanolamine; the mass ratio of the silane coupling agent-modified nano-silica to the first stabilizer is preferably (1 - 1.5):(3 - 3.5). In the present invention, the first stabilizer can improve the dispersibility and stability of the nano-silica.

[0078] As an implementation manner, the mass ratio of the silane coupling agent-modified nano-silica to the first stabilizer can be (1 - 1.5):(3.1 - 3.3).

[0079] In the present invention, the cationic surfactant preferably includes cetyltrimethylammonium chloride; the mass ratio of the silane coupling agent-modified nano-silica to the cationic surfactant is preferably (1 - 3):7, more preferably 3:7. Limiting the mass ratio of the silane coupling agent-modified nano-silica to the cationic surfactant within the above ranges in the present invention can improve the demulsification effect of the demulsifier.

[0080] In the present invention, the mixing of the silane coupling agent-modified nano-silica, the inorganic solvent, the first stabilizer, and the cationic surfactant is preferably to mix the silane coupling agent-modified nano-silica and the inorganic solvent, and then add the first stabilizer and the cationic surfactant.

[0081] The present invention has no special limitation on the operation of mixing the silane coupling agent-modified nano-silica with the inorganic solvent, and the technical solutions for preparing the mixed material well-known to those skilled in the art can be adopted.

[0082] In the present invention, the concentration of the solution obtained by mixing the silane coupling agent-modified nano-silica with the inorganic solvent is preferably 0.005-0.01 wt%. As an embodiment, the concentration of the solution obtained by mixing the silane coupling agent-modified nano-silica with the inorganic solvent can be 0.006 wt%, 0.007 wt%, 0.008 wt% or 0.009 wt%.

[0083] In the present invention, the first stabilizer and the cationic surfactant are preferably carried out under the condition of ultrasonic oscillation; the temperature of the ultrasonic oscillation is preferably 80-100 °C; the time of the ultrasonic oscillation is preferably 5-10 min. The present invention adopts ultrasonic oscillation to ensure that all raw materials are completely dissolved to form a suspension.

[0084] As an embodiment, the temperature of the ultrasonic oscillation can be 85-95 °C, and can also be 90 °C; the time of the ultrasonic oscillation can be 6-9 min, and can also be 7-8 min.

[0085] After obtaining the suspension, the present invention preferably mixes the suspension, the second stabilizer and the organic solvent for modification to obtain modified nano-silica.

[0086] In the present invention, the second stabilizer preferably includes urea; the organic solvent is preferably ethanol. In the present invention, the second stabilizer can improve the structural stability of the silane coupling agent-modified nano-silica.

[0087] In the present invention, the mass ratio of the suspension to the second stabilizer is preferably 100:(0.5-1). The present invention has no special limitation on the dosage of the organic solvent, and the dosage well-known to those skilled in the art can be adopted.

[0088] The present invention has no special limitation on the operation of mixing the suspension, the second stabilizer and the organic solvent, and the technical solutions for preparing the mixed material well-known to those skilled in the art can be adopted.

[0089] In the present invention, the temperature of the modification is preferably 115 - 150 °C; the time of the modification is preferably 45 - 50 h, more preferably 48 h; the modification is preferably carried out under stirring conditions; the stirring rate is preferably 100 - 200 revolutions per minute. In the present invention, the modification can graft cationic groups onto the active sites of the silane-coupling-agent-modified nano-silica to form a cationic contact layer, making the silane-coupling-agent-modified nano-silica have high surface activity and strong permeability, and improving the demulsification effect; limiting the process parameters of the modification within the above ranges can improve the modification effect, thereby further improving the demulsification effect.

[0090] As an embodiment, the temperature of the modification can be 120 - 130 °C; the stirring rate can be 150 revolutions per minute.

[0091] After the modification is completed, in the present invention, it is preferred to let the product obtained by the modification stand, centrifuge, filter, wash, and dry in sequence to obtain modified nano-silica.

[0092] The present invention has no special limitation on the operation of standing, and it can be left to stand until it reaches room temperature.

[0093] The present invention has no special limitation on the operation of centrifuging, and the operation well-known to those skilled in the art can be adopted.

[0094] The present invention has no special limitation on the operation of filtering, and the supernatant can be removed by adopting the filtering operation well-known to those skilled in the art.

[0095] The present invention has no special limitation on the operation of washing, and the impurities can be removed.

[0096] The present invention has no special limitation on the operation of drying, and it can be dried to a constant weight.

[0097] The components of the demulsifier provided by the present invention include a non-ionic polyether demulsifier; the non-ionic polyether demulsifier is preferably a fatty alcohol non-ionic polyether. In the present invention, the hydrophilic group (ether bond) of the non-ionic polyether demulsifier makes it easier to form hydrogen bonds with water molecules than asphaltene, thus destroying the asphaltene interfacial film.

[0098] In the present invention, the mass ratio of the modified nano-silica to the non-ionic polyether demulsifier is preferably 1:(5 - 20). As an embodiment, the mass ratio of the modified nano-silica to the non-ionic polyether demulsifier can be 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18 or 1:19. Limiting the mass ratio of the modified nano-silica to the non-ionic polyether demulsifier within the above ranges in the present invention can further improve the demulsification effect of the demulsifier.

[0099] The components of the demulsifier provided by the present invention include a solvent; the solvent is preferably deionized water; the mass ratio of the modified nano-silica to the solvent is preferably (0.005 - 0.01):(99.992 - 99.99). In the present invention, the solvent is used to dissolve the modified nano-silica and the non-ionic polyether demulsifier.

[0100] As an embodiment, the mass ratio of the modified nano-silica to the solvent can be 0.008:99.996, 0.01:99.995 or 0.007:99.992.

[0101] In the present invention, the modified nano-silica is modified with a cationic surfactant, making the system have high surface activity and strong permeability, capable of neutralizing and offsetting with the emulsifier, and destroying the stability of the emulsion interfacial film; at the same time, the active components on the surface of the nano-silica will also undergo chemical reactions with asphaltene and resin; the hydrophilic group (ether bond) of the non-ionic polyether demulsifier makes it easier to form hydrogen bonds with water molecules than asphaltene, destroying the asphaltene interfacial film; the synergistic effect of the modified nano-silica and the non-ionic polyether demulsifier can more quickly destroy the oil-water interfacial film, destroy the stability of the emulsion, reduce the viscosity of crude oil, and the dispersed small water droplets can spontaneously aggregate and settle under the action of gravity, so as to achieve the effect of demulsifying oil-water separation, making the demulsifier have moderate low interfacial tension and strong interfacial activity, and thus having excellent viscosity reduction ability and demulsification effect.

[0102] The demulsifier provided by the present invention has a wide application range and high universality, and can be used in various complex situations of different oilfields; the dosage of the demulsifier is small, the use concentration is low, and the cost of preparing the demulsifier is extremely low; among them, the unique interfacial activity and strong permeability of the modified nano-silica, in coordination with the hydrogen bond reconstruction process caused by the hydrophilic group of the non-ionic polyether demulsifier, can reduce the viscosity of heavy oil and achieve excellent demulsification effect, enabling the demulsifier to further improve the demulsification effect on heavy oil emulsions with less dosage, and there is no problem of secondary utilization, so it is applicable to a wide range of heavy oil emulsions; the demulsifier is clean, environmentally friendly and pollution-free, and an extremely small content can achieve an ideal demulsification effect, with a short demulsification time, high demulsification efficiency, and high clarity of the water phase after demulsification.

[0103] The present invention also provides a preparation method of the demulsifier according to the above technical solution, including:

[0104] Mix the modified nano-silica, the non-ionic polyether demulsifier and the solvent to obtain the demulsifier.

[0105] In the present invention, the mixing of the modified nano-silica, the non-ionic polyether demulsifier and the solvent is preferably to oscillate and mix the modified nano-silica and the solvent, and then add the non-ionic polyether demulsifier.

[0106] In the present invention, the time of oscillating and mixing is preferably 10 to 30 minutes. As an embodiment, the time of oscillating and mixing can be 15 to 25 minutes, and can also be 20 minutes.

[0107] The present invention has no special limitation on the operation of adding the non-ionic polyether demulsifier, as long as the non-ionic polyether demulsifier is completely dissolved.

[0108] The present invention also provides the application of the demulsifier described in the above technical solution or the demulsifier prepared by the preparation method described in the above technical solution in water-containing heavy oil.

[0109] The present invention has no special limitation on the operation of applying the demulsifier in water-containing heavy oil, and the application operation well-known to those skilled in the art can be adopted.

[0110] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts belong to the scope of protection of the present invention.

[0111] Example 1

[0112] The demulsifier is composed of the following components: modified nano-silica, non-ionic polyether demulsifier and solvent;

[0113] The modified nano-silica is nano-silica modified by a silane coupling agent and a cationic surfactant;

[0114] The non-ionic polyether demulsifier is fatty alcohol non-ionic polyether AEO-3;

[0115] The mass ratio of the modified nano-silica to the non-ionic polyether demulsifier is 1:7;

[0116] The solvent is deionized water; the mass ratio of the modified nano-silica to the solvent is 0.008:99.996;

[0117] The particle size of the modified nano-silica is 1 to 100 nm;

[0118] The preparation method of the demulsifier is:

[0119] Add the modified nano-silica to the solvent, oscillate in an ultrasonic oscillator for 15 minutes, and then add the non-ionic polyether demulsifier until it is completely dissolved to obtain the demulsifier;

[0120] The preparation method of the modified nano-silica is:

[0121] (1) In a 45 °C constant temperature water bath, n-hexane, nonylphenol polyoxyethylene ether and ultrapure water were respectively pipetted into a dry and clean three-necked flask according to a volume ratio of 20:6:3. After shaking well, ethanol was added dropwise until it was no longer turbid, and then the pH value was adjusted to 10 with concentrated ammonia water and stirred for 0.8 h to obtain a reverse microemulsion;

[0122] (2) Tetrabutyl titanate was injected into the reverse microemulsion obtained in the step (1), and stirred for 2.5 h. Then, it was centrifuged at 4500 r / min for 20 min. After filtering to remove the supernatant, the precipitate was washed with acetone and ethanol in a volume ratio of 1:1.5 to obtain a white gel; wherein, the mass ratio of the reverse microemulsion to tetrabutyl titanate is 3:1;

[0123] (3) The white gel obtained in the step (2) was placed in an oven at 115 °C and dried for 4 h, and then calcined in a muffle furnace at 500 °C for 4 h to obtain nano-silica with a transverse size of 20 - 50 nm and a thickness of 5 - 10 nm;

[0124] (4) Vinyltrimethoxysilane, a silane coupling agent, was added to 50 mL of deionized water and ultrasonicated for 10 min to obtain a silane coupling agent solution with a mass concentration of 0.5 wt%;

[0125] (5) Nano-silica was added to 50 mL of deionized water and ultrasonicated for 30 min to obtain a nano-silica dispersion with a mass concentration of 3 wt%;

[0126] (6) 50 mL of the silane coupling agent solution was added to 50 mL of the nano-silica dispersion under ultrasonic conditions and ultrasonicated for 60 min. Then, it was poured into a three-necked flask and stirred at 300 rpm and 60 °C for 12 h for modification. Then, it was cooled to room temperature, followed by filtration. It was washed three times with deionized water and ethanol respectively to remove impurities, and finally dried in a freeze dryer for 12 h to obtain silane coupling agent-modified nano-silica;

[0127] (7) The silane coupling agent-modified nano-silica obtained in the step (6) was mixed with deionized water to obtain a mixed solution with a mass concentration of 0.007 wt%; then triethanolamine and a cationic surfactant cetyltrimethylammonium chloride were added, and placed in an ultrasonic stirrer and oscillated at 95 °C for 7 min to obtain a suspension; wherein, the mass ratio of the silane coupling agent-modified nano-silica to triethanolamine is 1.5:3.5; the mass ratio of the silane coupling agent-modified nano-silica to the cationic surfactant is 3:7;

[0128] (8) Add 0.5 g of urea to 100 g of the suspension obtained in step (7), and at the same time add 20 mL of ethanol. Place it in a three-necked flask and modify it at 115 °C for 48 h. Then let it stand to room temperature. After taking it out, place it in a centrifuge and centrifuge at a speed of 6000 r / min for 10 min. Then filter, wash it with water and ethanol multiple times, and finally dry it under vacuum to obtain modified nano-silica; wherein, the modification is carried out under stirring conditions; the rotation speed of the stirring is 100 revolutions / min.

[0129] Example 2

[0130] The demulsifier is composed of the following components: modified nano-silica, non-ionic polyether demulsifier and solvent;

[0131] The modified nano-silica is nano-silica modified with a silane coupling agent and a cationic surfactant;

[0132] The non-ionic polyether demulsifier is fatty alcohol non-ionic polyether AEO-3;

[0133] The mass ratio of the modified nano-silica to the non-ionic polyether demulsifier is 1:13;

[0134] The solvent is deionized water;

[0135] The mass ratio of the modified nano-silica to the solvent is 0.01:99.995;

[0136] The particle size of the modified nano-silica is 1 - 100 nm;

[0137] The preparation method of the demulsifier is as follows:

[0138] Add the modified nano-silica to the solvent, oscillate it in an ultrasonic oscillator for 25 min, and then add the non-ionic polyether demulsifier until it is completely dissolved to obtain the demulsifier;

[0139] The preparation method of the modified nano-silica is as follows:

[0140] (1) In a 45 °C constant temperature water bath, respectively transfer n-hexane, nonylphenol polyoxyethylene ether and ultrapure water to a dry and clean three-necked flask according to a volume ratio of 20:5:3. After shaking well, add ethanol dropwise until it is no longer turbid, and then adjust the pH value to 10 with concentrated ammonia water and stir for 2 h to obtain a reverse microemulsion;

[0141] (2) Inject tetrabutyl titanate into the reverse microemulsion obtained in step (1), stir for 4 h, then centrifuge at 4500 r / min for 20 min, filter to remove the supernatant, and wash the precipitate with acetone and ethanol in a volume ratio of 1:2 to obtain a white gel; wherein, the mass ratio of the reverse microemulsion to tetrabutyl titanate is 3:1;

[0142] (3) Place the white gel obtained in step (2) in an oven at 120 °C and dry it for 4 h, then calcine it in a muffle furnace at 500 °C for 5 h to obtain nano-silica with a lateral size of 20 - 50 nm and a thickness of 5 - 10 nm;

[0143] (4) Add vinyltrimethoxysilane, a silane coupling agent, to 50 mL of deionized water and ultrasonicate for 10 min to obtain a silane coupling agent solution with a mass concentration of 0.1 wt%;

[0144] (5) Add nano-silica to 50 mL of deionized water and ultrasonicate for 30 min to obtain a nano-silica dispersion with a mass concentration of 1 wt%;

[0145] (6) Add 50 mL of the silane coupling agent solution to 50 mL of the nano-silica dispersion under ultrasonic conditions and ultrasonicate for 60 min. Then pour it into a three-necked flask, stir at a speed of 300 rpm and 60 °C for 12 h for modification. Then cool to room temperature, filter, wash three times with deionized water and ethanol respectively to remove impurities, and finally dry in a freeze dryer for 12 h to obtain silane coupling agent-modified nano-silica;

[0146] (7) Mix the silane coupling agent-modified nano-silica obtained in step (6) with deionized water to obtain a mixed solution with a mass concentration of 0.01 wt%. Then add triethanolamine and the cationic surfactant cetyltrimethylammonium chloride, put it into an ultrasonic stirrer, and oscillate at 95 °C for 10 min to obtain a suspension. Among them, the mass ratio of the silane coupling agent-modified nano-silica to triethanolamine is 1.5:3.3; the mass ratio of the silane coupling agent-modified nano-silica to the cationic surfactant is 3:7;

[0147] (8) Add 1 g of urea to 100 g of the suspension obtained in step (7), add 20 mL of ethanol at the same time, put it into a three-necked flask and modify it at 150 °C for 48 h. Then let it stand to room temperature, take it out and centrifuge it in a centrifuge at a speed of 4500 r / min for 10 min. Then filter, wash it with water and ethanol many times, and finally dry it under vacuum to obtain modified nano-silica. Among them, the modification is carried out under stirring conditions; the rotation speed of the stirring is 150 r / min.

[0148] Example 3

[0149] The demulsifier is composed of the following components: modified nano-silica, non-ionic polyether demulsifier and solvent;

[0150] The modified nano-silica is nano-silica modified with a silane coupling agent and a cationic surfactant;

[0151] The non-ionic polyether demulsifier is fatty alcohol non-ionic polyether AEO-3;

[0152] The mass ratio of the modified nano-silica and the non-ionic polyether demulsifier is 1:10;

[0153] The solvent is deionized water; the mass ratio of the modified nano-silica and the solvent is 0.007:99.992;

[0154] The particle size of the modified nano-silica is 1 - 100 nm;

[0155] The preparation method of the demulsifier is as follows:

[0156] Add the modified nano-silica into the solvent, oscillate it in an ultrasonic oscillator for 20 min, then add the non-ionic polyether demulsifier until it is completely dissolved to obtain the demulsifier;

[0157] The preparation method of the modified nano-silica is as follows:

[0158] (1) In a 45 °C constant temperature water bath, respectively transfer n-hexane, nonylphenol polyoxyethylene ether and ultrapure water into a dry and clean three-necked flask according to a volume ratio of 22:7:3, shake well, then add ethanol until it is no longer turbid, and then adjust the pH value to 12 with concentrated ammonia water, stir for 2 h to obtain a reverse microemulsion;

[0159] (2) Inject tetrabutyl titanate into the reverse microemulsion obtained in the step (1), stir for 4 h, then centrifuge at 4500 r / min for 20 min, filter to remove the supernatant, and wash the precipitate with acetone and ethanol in a volume ratio of 1:1 to obtain a white gel; among them, the mass ratio of the reverse microemulsion and tetrabutyl titanate is 3:1;

[0160] (3) Place the white gel obtained in the step (2) in an oven at 130 °C and dry for 4 h, then place it in a muffle furnace at 500 °C and calcine for 5 h to obtain nano-silica with a lateral size of 20 - 50 nm and a thickness of 5 - 10 nm;

[0161] (4) Add vinyltrimethoxysilane, a silane coupling agent, to 50 mL of deionized water and ultrasonicate for 10 min to obtain a silane coupling agent solution with a mass concentration of 0.3 wt%;

[0162] (5) Add nano-silica to 50 mL of deionized water and ultrasonicate for 30 min to obtain a nano-silica dispersion with a mass concentration of 1 wt%;

[0163] (6) Add 50 mL of the silane coupling agent solution to 50 mL of the nano-silica dispersion under ultrasonic conditions, and ultrasonicate for 60 min. Then pour it into a three-necked flask, stir at a speed of 300 rpm and 60 °C for 12 h for modification. Then cool it to room temperature, filter it, wash it three times with deionized water and ethanol respectively to remove impurities, and finally place it in a freeze dryer to dry for 12 h to obtain silane coupling agent-modified nano-silica;

[0164] (7) Mix the silane coupling agent-modified nano-silica obtained in step (6) with deionized water to obtain a mixed solution with a mass concentration of 0.005 wt%. Then add triethanolamine and the cationic surfactant cetyltrimethylammonium chloride, place it in an ultrasonic stirrer, and oscillate at 95 °C for 10 min to obtain a suspension; among them, the mass ratio of the silane coupling agent-modified nano-silica to triethanolamine is 1:3.5; the mass ratio of the silane coupling agent-modified nano-silica to the cationic surfactant is 3:7;

[0165] (8) Add 1 g of urea to 100 g of the suspension obtained in step (7), and at the same time add 20 mL of ethanol. Place it in a three-necked flask and modify it at 150 °C for 48 h. Then let it stand to room temperature, take it out and centrifuge it in a centrifuge at a speed of 4500 r / min for 10 min. Then filter it, wash it many times with water and ethanol, and finally dry it in vacuo to obtain modified nano-silica; among them, the modification is carried out under stirring conditions; the stirring speed is 200 revolutions / min.

[0166] Example 4

[0167] The demulsifier is composed of the following components: modified nano-silica, non-ionic polyether demulsifier and solvent;

[0168] The modified nano-silica is nano-silica modified with a silane coupling agent and a cationic surfactant;

[0169] The non-ionic polyether demulsifier is fatty alcohol non-ionic polyether AEO-3;

[0170] The mass ratio of the modified nano-silica to the non-ionic polyether demulsifier is 1:16;

[0171] The solvent is deionized water; the mass ratio of the modified nano-silica to the solvent is 0.01:99.99;

[0172] The particle size of the modified nano-silica is 1 - 100 nm;

[0173] The preparation method of the demulsifier is:

[0174] Add the modified nano-silica into a solvent, oscillate it in an ultrasonic oscillator for 25 min, then add a non-ionic polyether demulsifier until it is completely dissolved to obtain a demulsifier.

[0175] The preparation method of the modified nano-silica is as follows:

[0176] (1) In a 45 °C constant temperature water bath, respectively transfer n-hexane, nonylphenol polyoxyethylene ether and ultrapure water into a dry and clean three-necked flask according to a volume ratio of 25:7:4. After shaking well, add ethanol dropwise until it is no longer turbid, then adjust the pH value to 12 with concentrated ammonia water and stir for 2 h to obtain a reverse microemulsion.

[0177] (2) Inject tetrabutyl titanate into the reverse microemulsion obtained in step (1), stir for 4 h, then centrifuge at 4500 r / min for 20 min. After filtering to remove the supernatant, wash the precipitate with acetone and ethanol in a volume ratio of 1:2 to obtain a white gel. Among them, the mass ratio of the reverse microemulsion to tetrabutyl titanate is 3:1.

[0178] (3) Place the white gel obtained in step (2) in an oven at 125 °C and dry for 4 h, then calcine it in a muffle furnace at 500 °C for 5 h to obtain nano-silica with a lateral size of 20 - 50 nm and a thickness of 5 - 10 nm.

[0179] (4) Add vinyltrimethoxysilane, a silane coupling agent, to 50 mL of deionized water and ultrasonicate for 10 min to obtain a silane coupling agent solution with a mass concentration of 0.1 wt%.

[0180] (5) Add nano-silica to 50 mL of deionized water and ultrasonicate for 30 min to obtain a nano-silica dispersion with a mass concentration of 10 wt%.

[0181] (6) Add 50 mL of the silane coupling agent solution to 50 mL of the nano-silica dispersion under ultrasonic conditions, ultrasonicate for 60 min, then pour it into a three-necked flask, stir at a rotation speed of 300 rpm and 60 °C for 12 h for modification, then cool to room temperature, then filter, wash three times with deionized water and ethanol respectively to remove impurities, and finally place it in a freeze dryer and dry for 12 h to obtain silane coupling agent-modified nano-silica.

[0182] (7) Mix the nano-silica modified with the silane coupling agent obtained in step (6) with deionized water to obtain a mixed solution with a mass concentration of 0.008 wt%. Then add triethanolamine and the cationic surfactant cetyltrimethylammonium chloride, put it into an ultrasonic stirrer, and oscillate at 90 °C for 7 min to obtain a suspension; wherein, the mass ratio of the nano-silica modified with the silane coupling agent to triethanolamine is 1.5:3.5; the mass ratio of the nano-silica modified with the silane coupling agent to the cationic surfactant is 3:7;

[0183] (8) Add 1 g of urea to 100 g of the suspension obtained in step (7), and at the same time add 20 mL of ethanol. Put it into a three-necked flask and modify it at 150 °C for 48 h. Then let it stand to room temperature, take it out and put it into a centrifuge to centrifuge at a speed of 4500 r / min for 10 min. Then filter, wash it with water and ethanol multiple times, and finally dry it in vacuum to obtain modified nano-silica; wherein, the modification is carried out under stirring conditions; the rotation speed of the stirring is 100 revolutions / min.

[0184] Comparative Example 1

[0185] On the basis of Example 1, the modified nano-silica is omitted, and other conditions remain unchanged.

[0186] Comparative Example 2

[0187] On the basis of Example 1, the non-ionic polyether demulsifier is omitted, and other conditions remain unchanged.

[0188] Perform performance characterization on the demulsifiers prepared in Examples 1 to 4 and Comparative Examples 1 to 2

[0189] 1. Viscosity reduction effect

[0190] Refer to the petrochemical enterprise standard Q / SHCG 65-2013 "Technical Requirements for Viscosity Reducing Agents for Heavy Oil", and conduct a viscosity reduction experiment according to the determination standard of the viscosity reduction rate of water-soluble heavy oil viscosity reducing agents.

[0191] Prepare a salt solution containing 3 wt% NaCl and 0.3 wt% CaCl2. Use the salt solution to prepare a 1% solution of the liquid sample and a 0.3% solution of the solid sample for standby. Weigh 280 g (accurate to 0.1 g) of heavy oil sample into a beaker, add 120 g (accurate to 0.1 g) of the prepared sample solution, put it into a constant temperature water bath at 50 °C ± 1 °C for 1 h, adjust the rotation speed to 250 r / min, stir for 2 min under constant temperature conditions, and quickly measure the viscosity μ of the prepared heavy oil emulsion at 50 °C ± 1 °C with a rotational viscometer. The result is calculated according to formula I:

[0192]

[0193] In the formula: f is the shear dynamic viscosity reduction rate; μ0 is the viscosity of the crude oil sample at 50 °C, with the unit of mPa·s; μ is the viscosity of the oil-water mixture after stirring for 2 min, with the unit of mPa·s.

[0194] Table 1 Viscosity reduction rates of the demulsifiers prepared in Examples 1-4 and Comparative Examples 1-2

[0195]

[0196] As can be seen from Table 1, the viscosity reduction rates of the demulsifiers provided by the present invention are all higher than 90%. Among them, the viscosity reduction effect of Example 2 is the best, and the viscosity reduction rate is as high as 98.7%. The good viscosity reduction effect is conducive to destroying the oil-water interfacial film of heavy oil and promoting demulsification.

[0197] 2. Demulsification efficiency

[0198] Referring to the petroleum and natural gas industry standard SY / T 5281-2000 Detection method for the performance of crude oil demulsifiers (bottle test method), a demulsification experiment is carried out at 43 °C, the oil-water interface is observed, and the water separation amount is recorded.

[0199] Prepare the crude oil emulsion: Weigh 500 g of purified oil in the cup of an automatic mixer, and weigh 500 g of sewage in a beaker. Place the above two cups in a constant temperature water bath 5-10 °C lower than the dehydration temperature for preheating. Start the automatic mixer, and slowly and evenly add the sewage in the beaker to the cup of the automatic mixer and stir well to form an artificially prepared crude oil emulsion. Place the dehydration test bottle containing the crude oil emulsion sample in the constant temperature water bath for preheating until the temperature of the sample in the dehydration test bottle rises to the predetermined dehydration temperature. This temperature is measured by the thermometer in the blank control test bottle containing the sample, and the liquid level of the constant temperature water bath should be higher than the liquid level of the crude oil emulsion in the dehydration test bottle. Use a pipette to add a certain amount of demulsifier to the dehydration test bottle, and parallel samples should be set up for each demulsifier test. The oscillation of the dehydration test bottle adopts the manual oscillation method. After tightening the bottle cap, place the dehydration test bottle in an artificial oscillation box and oscillate horizontally 150 times with an amplitude greater than 20 cm. After mixing evenly, loosen the bottle cap and place the dehydration test bottle back in the constant temperature water bath for static settlement. Record the water separation amount at different times, and observe the color of the separated sewage and the condition of the oil-water interface. Evaluate the demulsification efficiency by the residual oil in the water sample. Specifically, use kerosene to separate the residual oil in the water and place it in a volumetric flask.

[0200] The demulsification efficiency is calculated by the following formula II:

[0201]

[0202] In the formula, E is the demulsification efficiency, with the unit of %; C0 is the initial oil concentration in the separated water, with the unit of mg / L; C is the residual oil content, with the unit of mg / L.

[0203] Table 2 Demulsification rates of the demulsifiers prepared in Examples 1-4 and Comparative Examples 1-2 over time

[0204]

[0205] As can be seen from Table 2, the demulsification rate of the demulsifier provided by the present invention is as high as 98.2%; and the demulsification rates all reach over 95% at 30 min, indicating that the demulsification process can be basically completed within 10 - 30 min, demonstrating that the demulsifier provided by the present invention has fast and efficient demulsification performance.

[0206] As can be seen from the above examples, the demulsifier provided by the present invention has excellent demulsification effect.

[0207] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can still be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A demulsifier, comprising the following components: modified nano-silica, non-ionic polyether demulsifier and solvent; The modified nano-silica is nano-silica modified with a silane coupling agent and a cationic surfactant.

2. The demulsifier according to claim 1, wherein The mass ratio of the modified nano-silica to the non-ionic polyether demulsifier is 1:(5 - 20).

3. The demulsifier according to claim 1, characterized in that, The preparation method of the modified nano-silica comprises the following steps: (1) Mix nano-silica modified with a silane coupling agent, an inorganic solvent, a first stabilizer and a cationic surfactant to obtain a suspension; (2) Mix the suspension obtained in step (1), a second stabilizer and an organic solvent, and carry out modification to obtain modified nano-silica.

4. The demulsifier according to claim 3, characterized in that, The first stabilizer in step (1) includes triethanolamine.

5. The demulsifier according to claim 3, characterized in that, The mass ratio of the nano-silica modified with a silane coupling agent to the first stabilizer in step (1) is (1 - 1.5):(3 - 3.5).

6. The demulsifier according to claim 3, characterized in that, The cationic surfactant in step (1) includes cetyl trimethyl ammonium chloride.

7. The demulsifier according to claim 3, characterized in that, The mass ratio of the nano-silica modified with a silane coupling agent to the cationic surfactant in step (1) is (1 - 3):

7.

8. The demulsifier according to claim 3, characterized in that, The second stabilizer in step (2) includes urea.

9. The preparation method of the demulsifier according to any one of claims 1 - 8, comprising: Mix the modified nano-silica, the non-ionic polyether demulsifier and the solvent to obtain a demulsifier.

10. The application of the demulsifier according to any one of claims 1 - 8 or the demulsifier prepared by the preparation method according to claim 9 in water-containing heavy oil.

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