Reverse demulsifier as well as preparation method and application thereof

Abstract

The invention discloses a reverse demulsifier and a preparation method and application thereof, the reverse demulsifier comprises a compound as shown in a structural formula I, in the formula I, n is less than 792, m is less than 447, and a is more than or equal to 3 and less than or equal to 10; r1, R2 and R3 are chain alkyl, the number n1 of carbon atoms in R1 is larger than or equal to 1 and smaller than or equal to 12, and the number n2 of carbon atoms in R2 and R3 is larger than or equal to 0 and smaller than or equal to 2. The molecular structure in the reverse demulsifier simultaneously contains amphiphilic groups of alkyl ester groups (oleophylic ends) and hydroxyl ammonium groups (hydrophilic ends), so that the reverse demulsifier has a better displacement effect at an oil-water interface film, and can reduce the polarity of asphaltene, so that the asphaltene has better dispersing capacity on the oil-water interface, can be quickly migrated to the interface from emulsion and is adsorbed to the oil-water interface; the branched chains and the main chain are integrally sawtooth-shaped, the molecular structure is highly branched, the surface tension of produced water can be effectively reduced, oil-water interface instability is promoted, and water-oil balance is broken.

Description

Technical Field

[0001] The present application relates to the technical field of demulsifiers, and in particular to a reverse demulsifier and a preparation method and application thereof. Background Art

[0002] Most oil fields in my country have entered the tertiary oil recovery stage. The addition of chemical agents such as polymers, alkali solutions and surfactants during the oil recovery process makes the crude oil composition more complex, resulting in an increase in the water content of the crude oil and the difficulty of demulsification, resulting in an increase in the cost of crude oil dehydration and energy waste. In particular, crude oil rich in asphaltene has the characteristics of high viscosity, small oil-water density difference, and poor fluidity. The multi-layered multi-emulsion formed is very stable, resulting in high demulsification temperature and dosage. Natural surfactants such as asphaltene in crude oil are adsorbed on the oil-water interface to form an interfacial film of a certain strength, which increases the difficulty of oil-water separation.

[0003] At present, a large number of relatively mature and widely used traditional polyether demulsifiers in China can no longer meet the production needs of efficient and rapid demulsification in oil fields due to low dehydration rate and slow dehydration speed. Summary of the invention

[0004] The invention provides a reverse phase demulsifier and a preparation method thereof, so as to solve the technical problems of low dehydration rate and slow dehydration speed in the prior art.

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

[0006] The first aspect of the present invention provides a reverse phase demulsifier, comprising a compound represented by the structural 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] The second aspect of the present invention provides a method for preparing the above-mentioned reverse phase demulsifier, comprising the following steps:

[0010] S1, mixing olefinic acid dimethylaminoethyl ester, olefinic acid ester and solvent, introducing nitrogen, and then adding initiator for polymerization to obtain a polymer; S2, mixing the polymer obtained in step S1 with solvent, and adding halohydrin for reaction to obtain the reverse phase demulsifier.

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

[0012] Furthermore, in the step S1, the volume ratio of the dimethylaminoethyl olefinate to the olefinic acid ester is 1:0.5-2, and the volume of the solvent is equal to the sum of the volumes of the dimethylaminoethyl olefinate and the olefinic acid ester.

[0013] Furthermore, the temperature of the polymerization reaction in step S1 is 45°C to 70°C.

[0014] Furthermore, the reaction temperature in step S2 is 70°C to 80°C.

[0015] Furthermore, in step S2, the molar ratio of the polymer to the halogenated alcohol is 0.3-1:1; and the volume of the solvent is equal to the volume of the polymer.

[0016] Furthermore, the substance obtained after adding the halogenated alcohol in step S2 is placed in a rotary evaporator to remove the solvent, and is washed and dried to obtain the reverse phase demulsifier.

[0017] The third aspect of the present invention provides the use of the above-mentioned inverse demulsifier in the demulsification treatment of oil field produced water.

[0018] Furthermore, the application step includes: adding the inverse demulsifier to the oilfield produced water sample to be treated, stirring and adding an auxiliary agent, and letting it stand.

[0019] Furthermore, the weight ratio of the reverse phase 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 .

[0020] The reverse demulsifier provided by the present invention has a molecular structure containing amphiphilic groups of alkyl ester groups (lipophilic end) and hydroxyl ammonium groups (hydrophilic end) at the same time, which has a better displacement effect at the oil-water interface film, can reduce the polarity of asphaltene, and make asphaltene have better dispersibility at the oil-water interface, can quickly migrate from the emulsion to the interface, and adsorb to the oil-water interface; the adsorbed asphaltene cannot continue to exist on the interface under the action of external forces, and eventually leads to interface instability; in addition, the side chain and the main chain are shaped like saw teeth as a whole, and the molecular structure is highly branched, which can effectively reduce the surface tension of produced water, promote oil-water interface instability, and break the water-oil balance. The above-mentioned reverse demulsifier contains ammonium ions, which can be ionized after being dissolved in produced water, promote potential neutralization, promote oil droplet aggregation, and more easily achieve demulsification. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0023] Figure 2 This is the IRC data diagram of dimethylaminoethyl acrylate, an AIBN attack monomer, 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 diagram of the chain initiation process of AIBN attacking dimethylaminoethyl acrylate in an embodiment of the present invention;

[0026] Figure 5 This is an IRC data diagram of the chain initiation process of dimethylaminoethyl acrylate after AIBN attacks dimethylaminoethyl acrylate in an embodiment of the present invention;

[0027] Figure 6 This is an IRC data diagram of the initiation process of AIBN attacking the ethyl acrylate chain in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order 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 part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] In a first aspect of the embodiments of the present application, a reverse phase demulsifier is provided, comprising a compound shown in 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 molecular structure of the reverse demulsifier contains amphiphilic groups of alkyl ester group (lipophilic end) and hydroxyl ammonium group (hydrophilic end), which has a better displacement effect at the oil-water interface membrane, can reduce the polarity of asphaltene, make asphaltene have better dispersion ability at the oil-water interface, can quickly migrate from the emulsion to the interface, and adsorb to the oil-water interface; the adsorbed asphaltene cannot continue to exist on the interface under the action of external force, and eventually leads to interface instability; in addition, the side chain and the main chain are sawtooth-like in overall view, and the molecular structure is highly branched, which can effectively reduce the surface tension of produced water, promote oil-water interface instability, break the water-oil balance, and solve the technical problems of low dehydration rate and slow dehydration speed of oil field produced water in the prior art. The above reverse demulsifier contains ammonium ions, which can be ionized after dissolving in produced water, promote potential neutralization, promote oil droplet aggregation, and make it easier to achieve demulsification.

[0033] The second aspect of the embodiment of the present application provides a method for preparing the above-mentioned reverse demulsifier, comprising the following steps: S1, mixing dimethylaminoethyl olefinate, olefinic acid ester and a solvent, introducing nitrogen, and then adding an initiator for polymerization to obtain a polymer; S2, mixing the polymer obtained in step S1 with a solvent, and adding a halogenated alcohol for reaction to obtain a reverse demulsifier.

[0034] In the preparation method of the reverse phase demulsifier of the embodiment of the present application, the raw materials include monomers all containing olefin ester groups, and 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 of alkyl ester groups (lipophilic end) and hydroxyl ammonium groups (hydrophilic end), so that the displacement effect at the oil-water interface film is better, the oil-water interface energy is reduced, the interface film is broken, and the produced water demulsification is promoted.

[0035] In the embodiment of the present application, the dimethylaminoethyl olefinic acid ester in the raw material of step S1 can be dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate or dimethylaminoethyl ethyl acrylate. The olefinic acid ester can be ethyl acrylate, propyl acrylate, butyl acrylate or methacrylate, etc. The solvents in step S1 and step S2 are both selected from one or more of ethanol, isooctyl alcohol and n-propanol.

[0036] Specifically, the initiator of step S1 is selected from one or more of azobisisobutyronitrile, potassium persulfate, and ammonium persulfate. The amount of the initiator added is 0.5% of the total mass of the reaction monomer. Further, in step S2, the substance obtained after the reaction of the halohydrin is added, the solvent is removed in a rotary evaporator, and the solution is washed with ethyl acetate, and the reverse phase demulsifier is obtained after drying. The halohydrin is selected from 3-chloro-1-propanol, 4-chloro-1-butanol, etc. The halohydrin is added in step S2 to quaternize the polymer.

[0037] The preparation method of the reverse demulsifier of the embodiment of the present application includes the steps of pretreatment and polymerization reaction of monomers, ionization modification of halogenated alcohols, rotary distillation and vacuum drying purification. The method is simple and easy to implement, low in cost, and easy to promote on a large scale.

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

[0039] Specifically, according to the dosage of 30mg / L to 60mg / L, the reverse phase demulsifier is added to the oilfield produced water sample to be treated, stirred and 10mg / L to 20mg / L of 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°C.

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

[0041] Example 1

[0042] A reverse phase demulsifier, comprising a compound shown in formula I:

[0043]

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

[0045] The preparation method of the reverse demulsifier comprises the following steps: adding 30g of ethanol, 20g of dimethylaminoethyl acrylate and 10g of methyl acrylate into a three-necked flask at 55°C; degassing with nitrogen for 30min to remove oxygen; then adding 0.5wt% of azobisisobutyronitrile (AIBN) as an initiator accounting for the total weight of the above solution, polymerizing for 10h, then putting the obtained polymer and 4-chloro-1-butanol into a new flask at a molar ratio of 1:1, adding ethanol to 1 / 3 of the volume of the flask, reacting at 80°C for 16h to obtain a preliminary product. The preliminary product is placed in a rotary evaporator at 45°C to remove the solvent, then repeatedly washed with ethyl acetate for 3 times, and vacuum dried to obtain a reverse demulsifier.

[0046] Feasibility determination of the above-mentioned reverse demulsifier preparation method:

[0047] It is implemented by the simulation software Gaussian 09W. First, the molecular structures of the reactants and target products are constructed, and the molecular structures of the intermediate products are estimated. Transition state searches are performed, and the geometric structures of the products, transition states, and intermediates in the reaction system are continuously optimized. The IRC theory is used to verify the reliability of the transition state, thereby verifying the success of the product preparation.

[0048] Figure 1 , Figure 2They represent the chain initiation process of the initiator AIBN attacking the methyl acrylate and dimethylaminoethyl acrylate monomers, respectively. Figure 1 From the IRC curve in, we can see that the total energy of the product is lower than that of the raw material, the reaction is exothermic, and proceeds spontaneously, which can be carried out under the given experimental conditions.

[0049] Figure 3-6 They represent the chain transfer process after the initiator AIBN attacks the two monomers. Figure 3-6 From the IRC curve in, we can see that the total energy of the product is lower than that of the raw material, the reaction is exothermic, and proceeds spontaneously, which can be carried out under the given experimental conditions.

[0050] Table 1 Calculation results of reaction energy barriers and free energy changes in chain initiation and chain transfer processes of polymerization

[0051]

[0052] In summary, this polymerization reaction is an exothermic reaction, and according to the activation energy barrier data in Table 1, the activation energy values ​​of the newly added monomers methyl acrylate or dimethylaminoethyl acrylate on the chain during the chain transfer process are very small, both about 40 kJ / mol, and there is no obvious rate difference; the free energy change is also stable, both are exothermic reactions, and proceed spontaneously under given conditions. It proves that the two monomers can be polymerized and the polymerization reaction can be completed spontaneously.

[0053] Example 2

[0054] A reverse phase demulsifier, comprising a compound shown in formula I:

[0055]

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

[0057] The preparation method of the reverse demulsifier comprises the following steps: adding 45g of isooctyl alcohol, 20g of dimethylaminoethyl methacrylate and 10g of hexyl methacrylate into a three-necked flask at 55°C; degassing with nitrogen for 30 minutes to remove oxygen; then adding potassium persulfate accounting for 0.6wt% of the total weight of the above solution as an initiator, polymerizing for 10 hours, then putting the obtained polymer and 7-chloro-1-heptanol into a new flask at a molar ratio of 0.8:1, adding ethanol to 1 / 3 of the volume of the flask, reacting 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 repeatedly washed with ethyl acetate for 3 times, and vacuum dried to obtain a reverse demulsifier.

[0058] Example 3

[0059] A reverse phase demulsifier, comprising a compound shown in formula I:

[0060]

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

[0062] The preparation method of the reverse demulsifier comprises the following steps: adding 30g of n-propanol, 20g of dimethylaminoethyl ethyl acrylate and 10g of decyl ethyl acrylate into a three-necked flask at 55°C; degassing with nitrogen for 30min to remove oxygen; then adding 0.5wt% of ammonium persulfate as an initiator, polymerizing for 10h, then putting the obtained polymer and 10-chloro-1-decanol into a new flask at a molar ratio of 0.5:1, adding ethanol to 1 / 3 of the volume of the flask, reacting at 80°C for 16h to obtain a preliminary product. The preliminary product is placed in a rotary evaporator at 45°C to remove the solvent, then repeatedly washed with ethyl acetate for 3 times, and vacuum dried to obtain a reverse demulsifier.

[0063] The produced water of shale oil field in a well area of ​​Shengli Oilfield, Dongying has high oil content (2338.625mg / L) and high content of colloid asphaltene (about 200mg / L). The reverse phase demulsifiers of Examples 1 to 3 are added to the above-mentioned oilfield produced water samples to be treated according to the dosage of 50mg / L, stirred at a speed of 100rpm for 3min, and then 20mg / L cationic polyacrylamide is added, and stirred at a speed of 100rpm for 10min, and the treatment is completed after standing for 1h. After the reverse phase demulsifiers of Examples 1 to 3 treat the above-mentioned oilfield produced water, the oil content is 25.47mg / L, 39.65mg / L, and 43.12mg / L respectively, and the oil removal rate is greater than 98%. The method of Example 1 is the best for treating this type of produced water.

[0064] The reverse demulsifier of Example 1 was used to treat the conventional oilfield produced water in Lijin County, Shengli Oilfield, Dongying, and the effect was also good. The reverse demulsifier of Example 1 was added to the above-mentioned oilfield produced water samples to be treated at a dosage of 50 mg / L, stirred at a speed of 100 rpm for 3 minutes, and then 10 mg / L of cationic polyacrylamide was added, and stirred at a speed of 100 rpm for 10 minutes. After standing for 1 hour, the treatment was completed. The oil content of the above-mentioned conventional oilfield produced water before and after treatment was 252.85 mg / L and 45.88 mg / L respectively. The oil content of the produced water after treatment was less than 50 mg / L, which met the oil content treatment standard of produced water in the region.

[0065] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A reverse demulsifier, characterized in that: Including compounds shown in 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.

2. The method for preparing the reverse phase demulsifier according to claim 1, characterized in that: The following steps are involved: S1, mixing olefinic acid dimethylaminoethyl ester, olefinic acid ester and solvent, introducing nitrogen, and then adding initiator for polymerization to obtain a polymer; S2, mixing the polymer obtained in step S1 with a solvent, and adding a halogenated alcohol to react, thereby obtaining the reverse phase demulsifier.

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

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

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

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

8. Use of the inverse demulsifier according to claim 1 or the inverse demulsifier prepared by the preparation method according to any one of claims 2 to 7 in demulsification treatment of oilfield produced water.

9. The use according to claim 8, characterized in that: The application steps include: adding the reverse phase demulsifier into the oilfield produced water sample to be treated, stirring, adding an auxiliary agent, and standing.

10. The use according to claim 9, characterized in that: The weight ratio of the reverse phase 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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