Macromolecular demulsifier as well as preparation method and application thereof

Abstract

The invention discloses a macromolecular demulsifier as well as a preparation method and application thereof, and belongs to the technical field of oil exploitation. The polymer demulsifier has a structure as shown in a formula (I): # imgabs0 # formula (I); wherein R is selected from any one of NH2-(CH2CH2NH) m-CH2CH2, and m represents an integer from 1 to 4; n represents an integer from 25 to 600; a represents an integer from 60 to 200; and b represents an integer of 40-150. The macromolecular demulsifier has a good demulsification effect, improves the water phase cleanliness of demulsified dehydrated water, is suitable for various working conditions and environments, and solves the problem of difficulty in treatment of crude oil produced in oil fields in the prior art.

Description

Technical Field

[0001] The present application relates to a polymer demulsifier and a preparation method and application thereof, belonging to the technical field of petroleum extraction. Background Art

[0002] As oilfield development enters the middle and late stages, the extensive use of surfactants and polymers in secondary and tertiary oil recovery processes increases the emulsified oil content in the produced fluid, making oil-water separation more difficult. Traditional demulsifiers, such as inorganic salts and low-molecular-weight surfactants, suffer from high dosages, poor effectiveness, and the potential for secondary contamination, making them difficult to effectively treat these complex emulsions.

[0003] Chinese invention patent CN103709390B discloses a block polyether demulsifier using polyethyleneimine as an initiator and its preparation method, which demonstrates excellent demulsification performance for W / O emulsions produced after polymer flooding in oil fields. However, the demulsifier's relatively low molecular weight limits its universal applicability. Furthermore, as a nonionic demulsifier, in practical applications, it requires the addition of a cationic polymeric water purifier to improve water quality, increasing treatment costs. Summary of the Invention

[0004] The present invention aims to provide a polymer demulsifier and its preparation method and application, which has good demulsification effect, improves the cleanliness of the water phase of demulsified water, is applicable to various working conditions, and solves the problem of difficult treatment of crude oil in existing oil fields.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is: According to one aspect of the present application, a polymer demulsifier is provided, having a structure as shown in formula (I): Formula (I); wherein R is selected from any one of NH2-(CH2CH2NH)m-CH2CH2, and m represents an integer of 1-4; n represents an integer from 25 to 600; a represents an integer from 60 to 200; b represents an integer from 40 to 150.

[0006] Optionally, the molecular weight of the polymer demulsifier is 10,000-35,000.

[0007] According to another aspect of the present application, there is provided a method for preparing the polymer demulsifier as described in any one of the above, comprising: (1) Add polyethyleneimine and alkaline catalyst into a reactor, heat and stir, and perform vacuum and nitrogen replacement to ensure that there is no moisture and oxygen in the reactor. Then, introduce propylene oxide at 130-140°C. After the reaction is completed, cool to 120-130°C, and then introduce ethylene oxide to obtain polyether. (2) Add polyethylene polyamine and solvent into a flask, then add epichlorohydrin dropwise. The temperature during the addition process should be controlled at <30°C. After the addition is completed, keep the temperature at 20-30°C for 14-18 hours to obtain the modifier. (3) Add polyether into the flask, heat it to 85-95℃, then add the modifier dropwise. After the addition is complete, keep the temperature and react for 2-3 hours to obtain the crude polymer demulsifier. (4) Add n-hexane to the crude polymer demulsifier to extract and separate the two phases, collect the target product in the lower layer, and heat the target product to 140-160°C and perform vacuum distillation to remove the solvent to obtain the polymer demulsifier.

[0008] Optionally, in step (1), the mass ratio of the polyethyleneimine, propylene oxide and ethylene oxide is 1:(0.8-10):(0.4-8); The alkaline catalyst accounts for 0.3-1 wt% of the total mass of propylene oxide and ethylene oxide.

[0009] Optionally, in step (1), the alkaline catalyst is selected from any one of potassium hydroxide, sodium hydroxide, and potassium methoxide.

[0010] Optionally, in step (1), the molecular weight of the polyethyleneimine is 1000-25000.

[0011] Optionally, in step (2), the molar ratio of the polyethylene polyamine to epichlorohydrin is 1:(1-2).

[0012] Optionally, in step (2), the polyethylene polyamine is selected from any one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine; The solvent is selected from any one of ethanol, ethylene glycol, and ethylene glycol monobutyl ether.

[0013] Optionally, in step (3), the mass ratio of the modifier to the polyether is 1:(10-50).

[0014] According to another aspect of the present application, there is provided the use of any of the above-mentioned polymer demulsifiers in the process of demulsification and dehydration of produced crude oil, wherein the amount of the polymer demulsifier used is 90-110 ppm.

[0015] The beneficial effects of this application include but are not limited to: 1. The polymer demulsifier of this application has a high molecular weight. Its long chain structure can bridge oil and water droplets to form larger aggregates, which in turn coalesce, delaminate, and demulsify, effectively removing water from crude oil, reducing its water content and ensuring the standard water content for export. Furthermore, it has a certain cationicity, which not only allows it to form ion pairs with the emulsifier molecules in anionic emulsifiers, thereby destroying the emulsifier's coating and destabilizing the emulsion, but also neutralizes the negative surface charge of suspended solids, thereby improving the cleanliness of the aqueous phase to a certain extent.

[0016] 2. The polymer demulsifier of this application uses a branched polyethyleneimine as the initiator, which inherently possesses a certain degree of branching and molecular weight. This is then ring-opening polymerized with propylene oxide and ethylene oxide to form a polyether with long, highly branched segments, significantly reducing interfacial tension. By optimizing the ratio of propylene oxide to ethylene oxide, the contact points of the demulsifier molecules in the water and oil phases can be adjusted, increasing the area occupied by the molecules at the oil-water interface and thus effectively improving demulsification performance.

[0017] 3. The polymer demulsifier of this application is formed by reacting epichlorohydrin with polyethylene polyamine to form a long-chain segment modifier. This modifies the polyether to increase its molecular weight. Furthermore, through the modification experiment, a quaternization reaction occurs, resulting in a demulsifier with stronger cationicity and a water purification effect, thereby improving the cleanliness of the aqueous phase of the demulsified water.

[0018] 4. The preparation method of the polymer demulsifier of this application is simple, with readily available raw materials, and is amenable to industrial production. The resulting polymer demulsifier requires minimal usage, exhibits a high demulsification rate, produces clear water, and rapidly dehydrates oil. It is widely used in the treatment of oilfield produced fluids, effectively removing emulsified water from crude oil and improving its quality. It also helps reduce equipment corrosion in subsequent refining processes, eases operational complexity, reduces the amount of chemicals used in wastewater treatment, shortens treatment time, and thus reduces treatment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 This is the infrared spectrum of polymer demulsifier 3# in Example 3 of this application.

[0020] Figure 2 This is the GPC chart of polymer demulsifier 3# in Example 3 of this application. DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0022] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. The raw materials or instruments used, if the manufacturers are not specified, are all conventional products that can be purchased commercially.

[0023] Example 1 A method for preparing a polymer demulsifier, comprising: (1) Add 50 g of polyethyleneimine (PEI-3000) and 1.5 g of potassium hydroxide into a polymerization reactor, start heating and stirring, and perform vacuum and nitrogen replacement to ensure that there is no moisture and oxygen in the reactor. Slowly introduce 120 g of propylene oxide at 135 ° C. After the propylene oxide reaction is completed, cool to 125 ° C. Slowly introduce 100 g of ethylene oxide. After the reaction is completed, form a polyether; the reaction equation is as follows (where n is 70, a is 124, and b is 136):

[0024] (2) Add 103g of diethylenetriamine and 145g of ethylene glycol to a three-necked flask, slowly dropwise add 184g of epichlorohydrin, and control the temperature during the addition process to be less than 30°C. After the addition is complete, keep the temperature at 25°C for 16 hours to obtain a modifier; the reaction equation is as follows:

[0025] (3) Add 200 g of the polyether synthesized in step (1) into a three-necked flask, heat it to 90°C, and slowly dropwise add 10 g of the modifier synthesized in step (2). After the addition is complete, keep the temperature at 90°C for 2.5 hours to obtain a crude polymer demulsifier. The reaction equation is as follows:

[0026] (4) Add n-hexane to the crude polymer demulsifier to extract and separate the two phases. Collect the target product in the lower layer, and heat the target product to 150°C and distill under reduced pressure to remove the solvent to obtain polymer demulsifier 1# with a molecular weight of 23877.

[0027] Example 2 A method for preparing a polymer demulsifier, comprising: (1) 80 g of polyethyleneimine (PEI-5000) and 1.4 g of potassium hydroxide were added to a polymerization reactor, and the temperature was raised and stirred. The reactor was then vacuumed and replaced with nitrogen to ensure that there was no moisture or oxygen in the reactor. 120 g of propylene oxide was slowly introduced at 135° C. After the propylene oxide reaction was complete, the temperature was lowered to 125° C., and 70 g of ethylene oxide was slowly introduced. After the reaction was complete, a polyether was formed. The reaction equation was the same as that in step (1) of Example 1 (wherein n is 116, a is 129, and b is 99); (2) Add 146g of triethylenetetramine and 185g of ethylene glycol to a three-necked flask, slowly dropwise add 184g of epichlorohydrin, and control the temperature during the addition process to be less than 30°C. After the addition is complete, keep the temperature at 25°C for 16 hours to obtain a modifier; the reaction equation is as follows:

[0028] (3) Add 200 g of the polyether synthesized in step (1) into a three-necked flask, heat it to 90°C, and slowly dropwise add 10 g of the modifier synthesized in step (2). After the addition is complete, keep the temperature at 90°C for 2.5 hours to obtain a crude polymer demulsifier. The reaction equation is as follows:

[0029] (4) Add n-hexane to the crude polymer demulsifier to extract and separate the two phases. Collect the target product in the lower layer, and heat the target product to 150 °C and distill under reduced pressure to remove the solvent to obtain polymer demulsifier 2# with a molecular weight of 25172.

[0030] Example 3 A method for preparing a polymer demulsifier, comprising: (1) 200 g of polyethyleneimine (PEI-8000) and 1.8 g of potassium hydroxide were added to a polymerization reactor, and the temperature was raised and stirred. Vacuum and nitrogen replacement were performed to ensure that there was no moisture or oxygen in the reactor. 160 g of propylene oxide was slowly introduced at 135 ° C. After the propylene oxide reaction was completed, the temperature was lowered to 125 ° C. 100 g of ethylene oxide was slowly introduced. After the reaction was completed, a polyether was formed. The reaction equation was the same as that in step (1) of Example 1 (wherein n is 186, a is 110, and b is 91); (2) Add 189g of tetraethylenepentamine and 210g of ethylene glycol to a three-necked flask, slowly dropwise add 115g of epichlorohydrin, and control the temperature to be less than 30°C during the dropwise addition. After the dropwise addition is complete, heat and react at 25°C for 16h to obtain a modifier; the reaction equation is as follows:

[0031] (3) Add 220 g of the polyether synthesized in step (1) into a three-necked flask, heat it to 90°C, and slowly dropwise add 10 g of the modifier synthesized in step (2). After the addition is complete, keep the temperature at 90°C for 2.5 hours to obtain a crude polymer demulsifier. The reaction equation is as follows:

[0032] (4) Add n-hexane to the crude polymer demulsifier to extract and separate the two phases. Collect the target product in the lower layer, and heat the target product to 150 °C and distill under reduced pressure to remove the solvent to obtain polymer demulsifier 3# with a molecular weight of 26375.

[0033] Example 4 A method for preparing a polymer demulsifier, comprising: (1) Add 250 g of polyethyleneimine (PEI-10000) and 1.2 g of potassium hydroxide into a polymerization reactor, start heating and stirring, and perform vacuum and nitrogen replacement to ensure that there is no moisture and oxygen in the reactor. Slowly introduce 200 g of propylene oxide at 135 ° C. After the propylene oxide reaction is completed, cool to 125 ° C. and slowly introduce 100 g of ethylene oxide. After the reaction is completed, a polyether is formed. The reaction equation is the same as step (1) of Example 1 (wherein n is 233, a is 138, and b is 91); (2) Add 232g of pentaethylenehexamine and 235g of ethylene glycol to a three-necked flask, slowly dropwise add 102g of epichlorohydrin, and control the temperature to be less than 30℃ during the dropwise addition. After the dropwise addition is completed, keep the temperature at 25℃ for 16h to obtain the modifier; the reaction equation is as follows:

[0034] (3) Add 350 g of the polyether synthesized in step (1) into a three-necked flask, heat it to 90°C, and slowly dropwise add 10 g of the modifier synthesized in step (2). After the addition is complete, keep the temperature at 90°C for 2.5 hours to obtain a crude polymer demulsifier. The reaction equation is as follows:

[0035] (4) Add n-hexane to the crude polymer demulsifier to extract and separate the two phases. Collect the target product in the lower layer, and heat the target product to 150 °C and distill under reduced pressure to remove the solvent to obtain polymer demulsifier 4# with a molecular weight of 30110.

[0036] Comparative Example 1 A method for preparing a polymer demulsifier, comprising: 200 g of polyethyleneimine (PEI-8000) and 1.8 g of potassium hydroxide were added to a polymerization reactor, and the temperature was raised and stirred. Vacuum and nitrogen replacement were performed to ensure that there was no moisture or oxygen in the reactor. 160 g of propylene oxide was slowly introduced at 135 ° C. After the propylene oxide reaction was completed, the temperature was lowered to 125 ° C. 100 g of ethylene oxide was slowly introduced. After the reaction was completed, a polymer demulsifier D1# was formed with a molecular weight of 13983. The reaction equation was the same as that in step (1) of Example 1.

[0037] Comparative Example 2 A method for preparing a polymer demulsifier, comprising: (1) Add 189g of tetraethylenepentamine and 210g of ethylene glycol to a three-necked flask, slowly dropwise add 115g of epichlorohydrin, and control the temperature during the addition process to be less than 30°C. After the addition is complete, keep the temperature at 25°C for 16 hours to obtain a modifier; the reaction equation is as follows:

[0038] (2) Add 100 g of polyethyleneimine (PEI-8000) to a three-necked flask, heat it to 90°C, and slowly dropwise add 10 g of the modifier synthesized in step (1). After the addition is complete, keep the mixture at 90°C for 2.5 h to obtain a polymer demulsifier D2# with a molecular weight of 12294. The reaction equation is as follows (where n is 186):

[0039] Test Example 1: Crude oil demulsification experiment at a joint station in Shengli Oilfield Seven sets of experiments were conducted on produced fluid samples from a joint station in Shengli Oilfield. Each set of agents tested their demulsification performance under the same temperature and dosage conditions. These included samples of demulsifiers currently in use at the joint station (polyamines were used as the starting agent, polyoxypropylene polyoxyethylene ether, with a molecular weight of 4500). The polymer demulsifiers obtained in Examples 1-4 are designated 1#, 2#, 3#, and 4#, while those obtained in Comparative Examples 1-2 are designated D1# and D2#. The field oil samples had a water content of 35%, a dehydration temperature of 50°C, and an oil test volume of 80 mL. The test results for each agent are shown in Table 1: Table 1 Demulsifier dehydration data

[0040] As shown in Table 1, the polymer demulsifiers 1#-4# provided in Examples 1-4 have a high dehydration rate, all meeting the on-site requirement of a dehydration rate of ≥90%. The cleanliness of the water phase of the dehydrated water is higher than the on-site product indicator. The example products can also purify water while dehydrating. Moreover, by centrifuging the dehydrated upper layer of crude oil, polymer demulsifiers 1#-4# can achieve dehydration to a dry state, meeting the requirement of an upper layer water content of <0.8. Among them, polymer demulsifier 3# has the best effect, reaching a dehydration rate of 95.7% and an upper layer water content of 0.3.

[0041] Compared with the polymer demulsifier D1# provided in Comparative Example 1, the polymer demulsifiers 1#-4# provided in Examples 1-4 introduced a modifier, and the demulsification effect and water purification effect were greatly improved.

[0042] Compared with the polymer demulsifier D2# provided in Comparative Example 2, the polymer demulsifiers 1#-4# provided in Examples 1-4 and the on-site demulsifier samples all have block polyethers formed by propylene oxide and ethylene oxide in their structures. The blocks are arranged in a direction, which makes it easy to adsorb on the oil-water interface, weaken the original interfacial film strength, and make the interfacial film easily rupture, thereby achieving oil-water separation.

[0043] The polymer demulsifier 3# provided in Example 3 was characterized by FTIR. Figure 1 It can be seen that 1100cm -1 The peak at 3300-3500 cm is the stretching vibration peak of the ether bond (COC), which proves that propylene oxide, ethylene oxide and polyethylene imine undergo ring-opening polymerization. -1 The broad and strong peak is the stretching vibration absorption peak of tetraethylenepentamine (NH), which is at 910 cm -1 There is no peak at 736cm, which proves that there is no epoxy group. Epichlorohydrin has opened the ring and reacted with tetraethylenepentamine. -1 It is the characteristic absorption peak of quaternary ammonium substitution, proving that quaternization reaction has occurred.

[0044] Figure 2 This is the GPC diagram of polymer demulsifier 3#. The molecular weight of polymer demulsifier 3# provided in Example 3 was measured, and the weight average molecular weight can reach 26375.

[0045] The foregoing is merely an embodiment of the present application, and the scope of protection of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the technical ideas and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A polymer demulsifier, characterized in that: Having the structure shown in formula (I): Formula (I); wherein R is selected from any one of NH2-(CH2CH2NH)m-CH2CH2, and m represents an integer of 1-4; n represents an integer from 25 to 600; a represents an integer from 60 to 200; b represents an integer from 40 to 150.

2. The polymer demulsifier according to claim 1, characterized in that The molecular weight of the polymer demulsifier is 10,000-35,000.

3. A method for preparing the polymer demulsifier according to any one of claims 1 to 2, characterized in that: include: (1) Add polyethyleneimine and alkaline catalyst into a reactor, heat and stir, and perform vacuum and nitrogen replacement to ensure that there is no moisture and oxygen in the reactor. Then, introduce propylene oxide at 130-140°C. After the reaction is completed, cool to 120-130°C, and then introduce ethylene oxide to obtain polyether. (2) Add polyethylene polyamine and solvent into a flask, then add epichlorohydrin dropwise. The temperature during the addition process should be controlled at <30°C. After the addition is completed, keep the temperature at 20-30°C for 14-18 hours to obtain the modifier. (3) Add polyether into the flask, heat it to 85-95℃, then add the modifier dropwise. After the addition is complete, keep the temperature and react for 2-3 hours to obtain the crude polymer demulsifier. (4) Add n-hexane to the crude polymer demulsifier to extract and separate the two phases, collect the target product in the lower layer, and heat the target product to 140-160°C and perform vacuum distillation to remove the solvent to obtain the polymer demulsifier.

4. The method according to claim 3, characterized in that In step (1), the mass ratio of polyethyleneimine, propylene oxide and ethylene oxide is 1: (0.8-10): (0.4-8); The alkaline catalyst accounts for 0.3-1 wt% of the total mass of propylene oxide and ethylene oxide.

5. The method according to claim 3, characterized in that In step (1), the alkaline catalyst is selected from any one of potassium hydroxide, sodium hydroxide, and potassium methoxide.

6. The method according to claim 3, characterized in that In step (1), the molecular weight of the polyethyleneimine is 1000-25000.

7. The method according to claim 3, characterized in that In step (2), the molar ratio of polyethylene polyamine to epichlorohydrin is 1:(1-2).

8. The method according to claim 3, characterized in that In step (2), the polyethylene polyamine is selected from any one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine; The solvent is selected from any one of ethanol, ethylene glycol, and ethylene glycol monobutyl ether.

9. The method according to claim 3, characterized in that In step (3), the mass ratio of the modifier to the polyether is 1:(10-50).

10. Use of the polymer demulsifier according to any one of claims 1 to 2 in a process of demulsifying and dehydrating produced crude oil, wherein the amount of the polymer demulsifier used is 90-110 ppm.

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