Inverse demulsifiers, methods of making and using the same

Abstract

The application discloses a reverse demulsifier and a preparation method and application thereof. The reverse demulsifier comprises a compound shown in a structural formula I. In the formula I, n < 792, m < 447, 3 <= a <= 10; R1, R2 and R3 are all chain alkyl, wherein the number of carbon atoms in R1 is 1 <= n1 <= 12, and the number of carbon atoms in R2 and R3 is 0 <= n2 <= 2. The reverse demulsifier has the amphiphilic groups of alkyl ester groups (lipophilic end) and hydroxyl ammonium groups (hydrophilic end) in the molecular structure, has better replacement effect at the oil-water interface film, can reduce the polarity of asphaltene, makes the asphaltene have better dispersion capacity at the oil-water interface, can quickly migrate from the emulsion to the interface and be adsorbed to the oil-water interface, and has sawtooth-like branches and main chains in the whole, is highly branched in the molecular structure, can effectively reduce the surface tension of produced water, promotes the instability of the oil-water interface, and breaks the water-oil balance.

Description

Technical Field

[0001] This application relates to the field of demulsifier technology, and in particular to a reverse demulsifier, its preparation method and application. Background Technology

[0002] Most oilfields in my country have entered the tertiary oil recovery stage. The addition of polymers, alkalis, and surfactants during the recovery process complicates the crude oil composition, increasing water content and the difficulty of demulsification, leading to higher dehydration costs and energy waste. Crude oils rich in asphaltenes, in particular, are characterized by high viscosity, a small oil-water density difference, and poor fluidity, forming highly stable multi-layered emulsions that result in persistently high demulsification temperatures and chemical dosages. Natural surfactants such as asphaltenes in crude oil adsorb at the oil-water interface, forming a strong interfacial film that further complicates oil-water separation.

[0003] Currently, many mature and widely used traditional polyether demulsifiers in China are no longer able to meet the production needs of oil fields for efficient and rapid demulsification due to their low dehydration rate and slow dehydration speed. Summary of the Invention

[0004] This invention provides a reverse demulsifier and its preparation method to solve the technical problems of low dehydration rate and slow dehydration speed in the prior art.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0006] In a first aspect, the present invention provides a reverse demulsifier comprising a compound represented by Formula I:

[0007]

[0008] In Formula I, n < 792, m < 447, 3 ≤ a ≤ 10; R1, R2, and R3 are all chain alkyl groups, wherein the number of carbon atoms in R1 is 1 ≤ n1 ≤ 12, and the number of carbon atoms in R2 and R3 is 0 ≤ n2 ≤ 2.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned reverse demulsifier, comprising the following steps:

[0010] S1. Mix dimethylaminoethyl acrylate, acrylate and solvent, purge with nitrogen gas, then add an initiator to polymerize, to obtain a polymer; S2. Mix the polymer obtained in step S1 with solvent, then add a haloalcohol to react, to obtain the reverse demulsifier.

[0011] Furthermore, the initiator is selected from one or more of azobisisobutyronitrile, potassium persulfate, and ammonium persulfate.

[0012] Further, in step S1, the volume ratio of dimethylaminoethyl acrylate to acrylate is 1:0.5-2, and the volume of the solvent is equal to the sum of the volumes of dimethylaminoethyl acrylate and acrylate.

[0013] Furthermore, the polymerization temperature in step S1 is 45℃~70℃.

[0014] Furthermore, the reaction temperature in step S2 is 70℃~80℃.

[0015] Further, in step S2, the molar ratio of the polymer to the haloalcohol is 0.3 to 1:1; the volume of the solvent is equal to the volume of the polymer.

[0016] Further, the substance obtained after the reaction of the haloalcohol in step S2 is placed in a rotary evaporator to remove the solvent, and then washed and dried to obtain the reverse demulsifier.

[0017] A third aspect of the present invention provides the application of the above-described reverse demulsifier in the demulsification treatment of oilfield produced water.

[0018] Furthermore, the application steps include: adding the reverse demulsifier to the produced water sample from the oilfield to be treated, stirring and adding auxiliary agents, and then allowing it to stand.

[0019] Furthermore, the weight ratio of the reverse demulsifier to the produced water sample from the oilfield is 1:2×10⁻⁶. 4 ~1×10 5 The weight ratio of the auxiliary agent to the reverse demulsifier is 1:5×10. 4 ~1×10 5 .

[0020] The reverse demulsifier provided by this invention contains amphiphilic groups, including alkyl ester groups (lipophilic end) and hydroxyammonium groups (hydrophilic end), in its molecular structure. This results in better displacement at the oil-water interface, reducing the polarity of asphaltene and enhancing its dispersion at the oil-water interface. Asphaltene can rapidly migrate from the emulsion to the interface and adsorb there. Under external forces, the adsorbed asphaltene cannot persist at the interface, ultimately leading to interface instability. Furthermore, the serrated shape of the branches and main chain, along with the highly branched molecular structure, effectively reduces the surface tension of the produced water, promoting oil-water interface instability and disrupting the water-oil balance. The aforementioned reverse demulsifier contains ammonium ions, which ionize upon dissolution in produced water, promoting potential neutralization, oil droplet coalescence, and facilitating demulsification. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is an IRC data graph of AIBN attacking the monomer ethyl acrylate in an embodiment of the present invention;

[0023] Figure 2 This is an IRC data graph of AIBN attacking the monomer dimethylaminoethyl acrylate in an embodiment of the present invention;

[0024] Figure 3 This is an IRC data diagram of the ethyl acrylate chain initiation process after AIBN attacks ethyl acrylate in an embodiment of the present invention;

[0025] Figure 4 This is an IRC data graph of the AIBN attack on the dimethylaminoethyl acrylate chain initiation process in an embodiment of the present invention;

[0026] Figure 5 This is an IRC data graph of the initiation process of the dimethylaminoethyl acrylate chain after AIBN attack on dimethylaminoethyl acrylate in an embodiment of the present invention.

[0027] Figure 6 This is an IRC data diagram of the AIBN attack on the ethyl acrylate chain initiation process in an embodiment of the present invention. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] A first aspect of this application provides a reverse demulsifier, comprising a compound represented by formula I:

[0030]

[0031] In Formula I, n < 792, m < 447, 3 ≤ a ≤ 10; R1, R2, and R3 are all chain alkyl groups, wherein the number of carbon atoms in R1 is 1 ≤ n1 ≤ 12, and the number of carbon atoms in R2 and R3 is 0 ≤ n2 ≤ 2.

[0032] As can be seen from Formula I, the reverse demulsifier contains amphiphilic groups, namely alkyl ester groups (lipophilic end) and hydroxyammonium groups (hydrophilic end), in its molecular structure. This results in better displacement at the oil-water interface, reducing the polarity of asphaltene and enhancing its dispersion at the oil-water interface. Asphaltene can rapidly migrate from the emulsion to the interface and adsorb there. Under external forces, the adsorbed asphaltene cannot persist at the interface, ultimately leading to interface instability. Furthermore, the branched and main chains, viewed as a whole, resemble serrated edges, exhibiting a highly branched molecular structure. This effectively reduces the surface tension of produced water, promotes oil-water interface instability, disrupts the water-oil balance, and solves the technical problems of low dehydration rate and slow dehydration speed in existing oilfield produced water technologies. The aforementioned reverse demulsifier contains ammonium ions, which ionize upon dissolving in produced water, promoting potential neutralization, oil droplet coalescence, and facilitating demulsification.

[0033] A second aspect of the present application provides a method for preparing the above-mentioned reverse demulsifier, comprising the following steps: S1, mixing dimethylaminoethyl acrylate, acrylate and solvent, purging with nitrogen gas, and then adding an initiator to polymerize to obtain a polymer; S2, mixing the polymer obtained in step S1 with a solvent, and then adding a haloalcohol to react to obtain the reverse demulsifier.

[0034] In the preparation method of the reverse demulsifier in this application embodiment, the raw materials include monomers all containing ester groups. The ester groups highly activate the carbon-carbon double bonds, greatly promoting the polymerization of free radicals, increasing the molecular weight of the polymer, and thus improving the demulsification effect. In addition, the monomers in the raw materials simultaneously contain amphiphilic groups, namely alkyl ester groups (lipophilic end) and hydroxyammonium groups (hydrophilic end), which makes their displacement effect at the oil-water interface film better, reducing the oil-water interface energy, breaking the interface film, and promoting the demulsification of produced water.

[0035] In this embodiment, the dimethylaminoethyl acrylate in step S1 can be dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, or dimethylaminoethyl ethyl ethyl acrylate. The acrylate can be ethyl acrylate, propyl acrylate, butyl acrylate, or methacrylates, etc. The solvents in steps S1 and S2 are selected from one or more of ethanol, isooctanol, and n-propanol.

[0036] Specifically, the initiator in step S1 is selected from one or more of azobisisobutyronitrile, potassium persulfate, and ammonium persulfate. The amount of initiator added is 0.5% of the total mass of the reacting monomers. Further, the substance obtained after the reaction with the haloalcohol in step S2 is placed in a rotary evaporator to remove the solvent, washed with ethyl acetate, and dried to obtain a reverse-phase demulsifier. The haloalcohol is selected from 3-chloro-1-propanol, 4-chloro-1-butanol, etc. The addition of the haloalcohol in step S2 quaternizes the polymer.

[0037] The method for preparing the reverse demulsifier in this application includes the steps of monomer pretreatment and polymerization reaction, ionization modification of haloalcohol, rotary distillation and vacuum drying purification. The method is simple, easy to implement, low in cost, and easy to promote on a large scale.

[0038] A third aspect of this application provides the application of the above-described reverse demulsifier or the reverse demulsifier prepared by the above-described preparation method in the demulsification treatment of oilfield produced water.

[0039] Specifically, the reverse demulsifier is added to the produced water sample from the oilfield to be treated at a dosage of 30 mg / L to 60 mg / L. After stirring, 10 mg / L to 20 mg / L of an auxiliary agent is added, and the treatment is completed after standing. The auxiliary agent is selected from one or more of cationic polyacrylamide, chitosan quaternary ammonium salt, and polyaluminum chloride. The demulsification temperature is 50℃.

[0040] All reagents used in the following examples are commercially available.

[0041] Example 1

[0042] An anti-emulsifier comprising a compound represented by formula I:

[0043]

[0044] In the above structural formula, n < 100 and m < 55.

[0045] The preparation method of the reverse demulsifier includes the following steps: At 55°C, 30g of ethanol, 20g of dimethylaminoethyl acrylate, and 10g of methyl acrylate are added to a three-necked flask; the mixture is degassed with nitrogen for 30 minutes to remove oxygen; then, 0.5wt% of azobisisobutyronitrile (AIBN) is added as an initiator, and polymerization is carried out for 10 hours. The resulting polymer is then added to a new flask with 4-chloro-1-butanol at a molar ratio of 1:1, and ethanol is added to 1 / 3 of the flask volume. The mixture is reacted at 80°C for 16 hours to obtain a preliminary product. The preliminary product is placed in a rotary evaporator at 45°C to remove the solvent, then washed repeatedly three times with ethyl acetate, and dried under vacuum to obtain the reverse demulsifier.

[0046] Feasibility assessment of the above-mentioned method for preparing reverse demulsifier:

[0047] The simulation was performed using Gaussian 09W software. First, the molecular structures of the reactants and target products were constructed, and the molecular structures of intermediate products were predicted. Transition state search was conducted, and the geometric structures of products, transition states, and intermediates in the reaction system were continuously optimized. The reliability of the transition state was verified by combining IRC theory, thereby verifying the success of product preparation.

[0048] Figure 1 , Figure 2These represent the chain initiation processes of the initiator AIBN attacking the monomers of methyl acrylate and dimethylaminoethyl acrylate, respectively. Figure 1 The IRC curves show that the total energy of the product is lower than that of the raw materials, the reaction is exothermic and spontaneous, and it can proceed under the given experimental conditions.

[0049] Figure 3-6 These represent the chain propagation process after the initiator AIBN attacks the two monomers, from... Figure 3-6 The IRC curves show that the total energy of the product is lower than that of the raw materials, the reaction is exothermic and spontaneous, and it can proceed under the given experimental conditions.

[0050] Table 1. Calculation results of reaction energy barriers and free energy changes in the chain initiation and chain propagation processes of polymerization reactions.

[0051]

[0052] In summary, this polymerization reaction is exothermic. According to the activation energy barrier data in Table 1, the activation energies of the newly added monomers methyl acrylate or dimethylaminoethyl acrylate during chain transfer are very similar, both around 40 kJ / mol, showing no significant rate difference. The free energy changes are also stable, indicating exothermic reactions that proceed spontaneously under given conditions. This proves that the two monomers can polymerize, and that the polymerization reaction can spontaneously complete.

[0053] Example 2

[0054] An anti-emulsifier comprising a compound represented by formula I:

[0055]

[0056] In the above structural formula, n < 200, m < 112.

[0057] The preparation method of the reverse demulsifier includes the following steps: At 55°C, 45g of isooctanol, 20g of dimethylaminoethyl methacrylate, and 10g of hexyl methacrylate are added to a three-necked flask; the mixture is degassed with nitrogen for 30 minutes to remove oxygen; then, potassium persulfate (0.6 wt% of the total weight of the above solution) is added as an initiator, and polymerization is carried out for 10 hours. The resulting polymer is then added to a new flask with 7-chloro-1-heptanol at a molar ratio of 0.8:1, and ethanol is added to 1 / 3 of the flask volume. The mixture is reacted at 80°C for 16 hours to obtain a preliminary product. The preliminary product is then placed in a rotary evaporator at 45°C to remove the solvent, followed by repeated washing three times with ethyl acetate, and vacuum drying to obtain the reverse demulsifier.

[0058] Example 3

[0059] An anti-emulsifier comprising a compound represented by formula I:

[0060]

[0061] In the above structural formula, n < 792, m < 447.

[0062] The preparation method of the reverse demulsifier includes the following steps: At 55°C, 30g of n-propanol, 20g of dimethylaminoethyl ethyl acrylate, and 10g of decyl ethyl acrylate are added to a three-necked flask; the mixture is degassed with nitrogen for 30 min to remove oxygen; then 0.5wt% ammonium persulfate is added as an initiator, and polymerization is carried out for 10 h. The resulting polymer is then added to a new flask with 10-chloro-1-decanol at a molar ratio of 0.5:1, and ethanol is added to 1 / 3 of the flask volume. The mixture is reacted at 80°C for 16 h to obtain a preliminary product. The preliminary product is then placed in a rotary evaporator at 45°C to remove the solvent, followed by repeated washing three times with ethyl acetate, and vacuum drying to obtain the reverse demulsifier.

[0063] The produced water from a shale oilfield in a well area of ​​the Shengli Oilfield in Dongying City had a high oil content (2338.625 mg / L) and a high content of asphaltenes (approximately 200 mg / L). The reverse demulsifiers from Examples 1 to 3 were added to the produced water samples at a dosage of 50 mg / L. After stirring at 100 rpm for 3 minutes, 20 mg / L of cationic polyacrylamide was added, and the mixture was stirred at 100 rpm for 10 minutes. After standing for 1 hour, the treatment was complete. After treatment with the reverse demulsifiers from Examples 1 to 3, the oil content of the produced water was 25.47 mg / L, 39.65 mg / L, and 43.12 mg / L, respectively, with oil removal rates all greater than 98%. The method described in Example 1 showed the best treatment effect for this type of produced water.

[0064] The reverse demulsifier from Example 1 was also used to treat produced water from the conventional oilfield in Lijin County, Shengli Oilfield, Dongying, with good results. The reverse demulsifier from Example 1 was added to the produced water samples to be treated at a dosage of 50 mg / L. After stirring at 100 rpm for 3 minutes, 10 mg / L cationic polyacrylamide was added, and the mixture was stirred at 100 rpm for 10 minutes. After standing for 1 hour, the treatment was complete. The oil content before and after treatment of the conventional oilfield produced water was 252.85 mg / L and 45.88 mg / L, respectively. The oil content of the treated produced water was less than 50 mg / L, meeting the oil content treatment standard for produced water in this region.

[0065] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A reverse demulsifier, characterized in that, Including compounds represented by Formula I: ； Formula I; In Formula I, n < 792, m < 447, 3 ≤ a ≤ 10; R1, R2, and R3 are all chain alkyl groups, wherein the number of carbon atoms in R1 is 1 ≤ n1 ≤ 12, and the number of carbon atoms in R2 and R3 is 0 ≤ n2 ≤ 2; the auxiliary agent of the reverse demulsifier is selected from one or more of cationic polyacrylamide, chitosan quaternary ammonium salt, and polyaluminum chloride.

2. The method for preparing the reverse demulsifier according to claim 1, characterized in that, Includes the following steps: S1. Mix dimethylaminoethyl acrylate, acrylate and solvent, purge with nitrogen gas, then add initiator to polymerize, to obtain polymer; S2. After mixing the polymer obtained in step S1 with a solvent, add a haloalcohol to react, thereby obtaining the reverse demulsifier.

3. The method for preparing the reverse demulsifier according to claim 2, characterized in that, The initiator is selected from one or more of azobisisobutyronitrile, potassium persulfate, and ammonium persulfate.

4. The method for preparing the reverse demulsifier according to claim 2, characterized in that, In step S1, the volume ratio of dimethylaminoethyl acrylate to acrylate is 1:0.5-2, and the volume of the solvent is equal to the sum of the volumes of dimethylaminoethyl acrylate and acrylate.

5. The method for preparing the reverse demulsifier according to claim 2, characterized in that, The polymerization reaction temperature in step S1 is 45℃~70℃; and / or, The reaction temperature in step S2 is 70℃~80℃.

6. The method for preparing the reverse demulsifier according to claim 2, characterized in that, In step S2, the molar ratio of the polymer to the haloalcohol is 0.3 to 1:1; the volume of the solvent is equal to the volume of the polymer.

7. The method for preparing the reverse demulsifier according to any one of claims 2 to 6, characterized in that, The substance obtained after reacting with the haloalcohol in step S2 is placed in a rotary evaporator to remove the solvent, and then washed and dried to obtain the reverse demulsifier.

8. The application of the reverse demulsifier according to claim 1 or the reverse demulsifier prepared by any one of claims 2 to 7 in the demulsification treatment of oilfield produced water.

9. The application according to claim 8, characterized in that, The application steps include: adding the reverse demulsifier to the produced water sample from the oilfield to be treated, stirring and adding auxiliary agents, and then letting it stand.

10. The application according to claim 9, characterized in that, The weight ratio of the reverse demulsifier to the oilfield produced water sample is 1:2×10. 4 ~1×10 5 ; The weight ratio of the auxiliary agent to the reverse demulsifier is 1:5×10. 4 ~1×10 5 .

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