Styrene-alkyl methacrylate-maleic acid alkyl ester terpolymers, processes for their preparation and use, and paraffin control agents and use thereof

Abstract

The present application relates to the technical field of oilfield exploitation, and discloses a styrene-methyl acrylate alkyl ester-maleic acid alkyl ester terpolymer, a preparation method and application thereof, and a wax removal and inhibition agent and application thereof.The terpolymer comprises structural unit A, structural unit B and structural unit C, can adsorb paraffin wax crystals or form a co-crystal with paraffin wax molecules to inhibit the aggregation and crystal growth of paraffin wax molecules, and can effectively inhibit the deposition of paraffin wax molecules.The wax removal and inhibition agent prepared by using the terpolymer has good wax removal and inhibition performance, can dissolve the crystallized paraffin wax, inhibit the aggregation and growth of paraffin wax crystals, and has the characteristics of high flash point and low freezing point, so that the wax removal and inhibition agent can be applied to severe cold and low temperature conditions and has a wide application range.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, specifically to a styrene-alkyl methacrylate-alkyl maleic acid terpolymer, its preparation method and application, and a wax-removing agent and its application. Background Technology

[0002] Most oilfields in my country, such as Daqing, Shengli, Jiangsu, Jidong, and Bohai, produce crude oil containing a certain amount of wax. In some oilfields, the wax content can even reach as high as 40%. Wax in formation crude oil usually exists in a dissolved state. However, during crude oil extraction, when the oil flow approaches the surface, the temperature is below the crude oil's cloud point, and the pressure is below its saturation pressure, lighter components begin to continuously overflow from the crude oil. The crude oil's ability to dissolve wax gradually weakens, and wax crystals continuously precipitate out in large quantities. Without wax removal and prevention treatment, wax easily precipitates, accumulates, grows, and deposits on the pipe walls, leading to wax buildup in tubing and equipment. This causes many serious consequences, such as increased flow resistance of oil and gas, well sticking, decreased production, increased energy consumption, and production shutdowns. Wax buildup in oil wells is one of the long-standing technical challenges faced by the domestic and international petroleum industries. It directly affects the efficient development of oilfields and the normal production of oil wells, while also restricting the extraction speed and crude oil recovery rate. With the deepening exploitation of oil and gas fields and the increasing demand for petroleum, wax removal and prevention are necessary during the extraction, transportation, and storage processes to ensure normal production. Using chemical agents to remove wax from oil and gas wells and pipelines is a widely used technique in oil fields. This is because chemical agents are typically added through the annulus or surface pipelines, thus not affecting normal well production or pipeline transportation, and providing excellent wax removal and prevention effects. For example, Elarbe B. Elganidi et al. synthesized polystearic acid-co-betaine acrylate as a flow modifier for reducing viscosity in Malaysian crude oil. Zhao et al. coated polymethyl acrylate, ethylene vinyl acetate copolymer, and polyoxoolefins with organically modified nanoclay to obtain a hybrid pour point depressant, which was then used for preventing wax buildup in diesel fuel. CN116693758A discloses a method for preparing a wax inhibitor from an imidazole olefin-α-olefin-maleic acid alkyl ester terpolymer. The method involves reacting maleic anhydride with a fatty alcohol to obtain an alkyl maleic acid ester, which is then reacted with imidazole olefin and α-olefin to obtain the wax inhibitor. Currently used wax inhibitors are not highly effective at removing and preventing wax from oil wells, resulting in some wells having a wax removal cycle of less than half a month. Furthermore, these wax inhibitors suffer from low wax removal and prevention efficiency, an inability to simultaneously achieve both wax removal and prevention effects, low flash point, high pour point, and unsuitability for low-temperature environments. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing wax removers and protectants, and to provide a styrene-alkyl methacrylate-alkyl maleic acid terpolymer, its preparation method and application, as well as wax removers and protectants and their applications.

[0004] To achieve the above objectives, the present invention provides a styrene-alkyl methacrylate-alkyl maleate terpolymer, the terpolymer comprising structural unit A, structural unit B, and structural unit C.

[0005] The structural formula of structural unit A is:

[0006]

[0007] The structural formula of structural unit B is:

[0008]

[0009] The structural formula of structural unit C is:

[0010]

[0011] R1, R2, and R3 are each independently selected from straight-chain alkyl groups of C8-C30.

[0012] A second aspect of the present invention provides a method for preparing the terpolymer described herein, the method comprising the following steps:

[0013] (1) In the presence of a solvent and an initiator, monomer A, which provides structural unit A, monomer B, which provides structural unit B, and monomer C, which provides structural unit C, are subjected to a polymerization reaction.

[0014] (2) Add fatty alcohols to the polymerization product to carry out esterification reaction.

[0015] A third aspect of the present invention provides a styrene-alkyl methacrylate-alkyl maleic acid terpolymer prepared by the preparation method described in the present invention.

[0016] The fourth aspect of the present invention provides the application of the terpolymer described herein as a wax remover.

[0017] A fifth aspect of the present invention provides a wax remover comprising the terpolymer described in the present invention and a solvent.

[0018] The sixth aspect of this invention provides the application of the wax-removing and anti-waxing agent described herein in oil extraction.

[0019] The ternary copolymer provided by this invention can adsorb paraffin crystals or form eutectics with paraffin molecules, thereby inhibiting paraffin molecule aggregation and crystal growth. The resulting wax-removing and anti-wax agent has a certain wax-dissolving ability, capable of dissolving crystallized paraffin, improving wax blockage, extending the wax removal cycle, and exhibiting good wax-removing and anti-wax effects. The wax-removing and anti-wax agent has a high flash point and low pour point, making it suitable for extremely cold and low-temperature conditions. Simultaneously, this wax-removing and anti-wax agent can also reduce the pour point and viscosity of crude oil, thus having a wide range of applications. The wax-removing rate of the wax-removing and anti-wax agent provided by this invention is generally above 0.033 g / min, and the wax prevention rate (2000 ppm) is generally above 75%. The wax-removing and anti-wax agent can effectively inhibit the precipitation of paraffin in natural gas condensate and prevent wax crystal growth. Only 1000 ppm of the wax-removing and anti-wax agent needs to be added to the condensate to maintain good fluidity at low-temperature conditions (-18℃). The main reason is likely that the ternary copolymer structure contains benzene rings and long alkyl chains, which can adsorb paraffin crystals or form eutectics with paraffin molecules, thereby inhibiting paraffin molecule aggregation and crystal growth. Furthermore, the copolymer forms a three-dimensional network structure, which effectively inhibits paraffin molecule deposition. In addition, the ternary copolymer and paraffin-removing agent provided by this invention have a simple preparation process, readily available raw materials, and are easy to industrialize. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] This invention provides a styrene-alkyl methacrylate-alkyl maleate terpolymer, the terpolymer comprising structural unit A, structural unit B, and structural unit C.

[0022] The structural formula of structural unit A is:

[0023]

[0024] The structural formula of structural unit B is:

[0025]

[0026] The structural formula of structural unit C is:

[0027]

[0028] R1, R2, and R3 are each independently selected from straight-chain alkyl groups of C8-C30.

[0029] According to a preferred embodiment of the present invention, R1, R2, and R3 are each independently selected from straight-chain alkyl groups of C14-C28.

[0030] According to a preferred embodiment of the present invention, R1 is preferably selected from one of C22 straight-chain alkyl groups and C18 straight-chain alkyl groups.

[0031] According to a preferred embodiment of the present invention, R2 is preferably selected from one of C26 straight-chain alkyl groups and C22 straight-chain alkyl groups.

[0032] According to a preferred embodiment of the present invention, R3 is preferably selected from one of C26 straight-chain alkyl groups and C22 straight-chain alkyl groups.

[0033] The aforementioned preferred styrene-alkyl methacrylate-alkyl maleic acid terpolymer, with its benzene ring and long alkyl chain in its structural formula, can adsorb paraffin crystals or form eutectics with paraffin molecules, thereby inhibiting paraffin molecule aggregation and crystal growth. Furthermore, the copolymer forms a three-dimensional network structure, effectively inhibiting paraffin molecule deposition. The resulting wax-removing and anti-wax agent has a certain wax-dissolving ability, capable of dissolving crystallized paraffin, improving wax blockage, and exhibiting good wax-removing and anti-wax effects.

[0034] In the embodiments of the present invention, structural unit A is a structural unit provided by styrene, structural unit B is a structural unit provided by octadecyl methacrylate and / or dodecyl methacrylate, and structural unit C is a structural unit provided by hexadecyl maleate and / or dodecyl maleate as examples to illustrate the advantages of the present invention, but without limiting the scope of the present invention.

[0035] The styrene-alkyl methacrylate-alkyl maleate terpolymer with the aforementioned structural units has a comb-like structure. Its side chain structure includes benzene rings, long alkyl chains, and polar groups. The long alkyl chains and benzene rings can form eutectics with paraffin molecules or adsorb paraffin crystals, inhibiting the aggregation and crystal growth of paraffin molecules. The copolymer molecules form a three-dimensional network structure, further inhibiting the aggregation of paraffin molecules. In addition, when copolymer molecules adsorb onto the surface of already formed paraffin crystals, the polar groups in their structure are exposed on the surface of the paraffin crystals, thereby changing the wettability of the paraffin crystals and further inhibiting the aggregation and crystal growth of paraffin crystals. The benzene rings and long alkyl chains in the copolymer molecules can also disperse the asphaltenes in crude oil, further improving the fluidity of crude oil and lowering its pour point.

[0036] In this invention, the content of each structural unit in the ternary copolymer can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, based on the total amount of the ternary copolymer, the content of structural unit A is 4-50 mol%, the content of structural unit B is 30-75 mol%, and the content of structural unit C is 33-66 mol%. Preferably, the content of structural unit A is 15-20 mol%, the content of structural unit B is 30-40 mol%, and the content of structural unit C is 45-55 mol%.

[0037] In this invention, the molar content of structural unit A, structural unit B and structural unit C is obtained by calculation based on the amount of material fed.

[0038] All terpolymers possessing the aforementioned characteristics can achieve the objectives of this invention. There are no special requirements for their preparation methods. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the preparation method of the terpolymer includes the following steps:

[0039] (1) In the presence of a solvent and an initiator, monomer A, which provides structural unit A, monomer B, which provides structural unit B, and monomer C, which provides structural unit C, are subjected to a polymerization reaction.

[0040] (2) Add fatty alcohols to the polymerization product to carry out esterification reaction.

[0041] According to a preferred embodiment of the present invention, the structural formula of monomer A is:

[0042]

[0043] The structural formula of monomer B is:

[0044]

[0045] The structural formula of monomer C is:

[0046]

[0047] In formula (2), R1 is defined in the same way as R1 in the present invention, and the fatty alcohol is a fatty alcohol that provides groups R2 and R3.

[0048] In step (1) of this invention, the amount of each reactant monomer can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the molar ratio of monomer A, monomer B, and monomer C is 0.1-1.5:0.5-2:0.5-1.5, preferably 0.1-0.5:0.5-1.5:1-1.5. In this invention, using an excess of monomer C is beneficial to the polymerization reaction.

[0049] In step (1) of this invention, there are no special requirements for the type of solvent. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the solvent is one or more of toluene, xylene, trimethylbenzene, naphtha, solvent oil and C9 aromatics, preferably xylene.

[0050] In step (1) of the present invention, the concentration of the total monomer in the solvent can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the concentration of the total monomer in the solvent is 0.005-0.015 mol / mL, preferably 0.009-0.012 mol / mL.

[0051] In step (1) of this invention, there are no special requirements for the type of initiator. Commonly used initiators in the prior art can be used in this invention. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the initiator is one or more of azobisisobutyronitrile, benzoyl peroxide, and tert-butyl peroxide, preferably tert-butyl peroxide.

[0052] In step (1) of the present invention, the molar ratio of the initiator to the total amount of monomer can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the molar ratio of the initiator to the total amount of monomer is 1:300-1000, preferably 1:500-800.

[0053] In step (1) of this invention, there are no special requirements for the polymerization reaction temperature. Commonly used polymerization reaction temperatures are applicable to this invention. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the polymerization reaction temperature is 110-150℃, preferably 120-140℃.

[0054] In step (1) of this invention, there are no special requirements for the polymerization reaction pressure. Commonly used copolymerization reaction pressures are applicable to this invention. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the polymerization reaction pressure is atmospheric pressure.

[0055] In step (1) of the present invention, the polymerization reaction time can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the polymerization reaction time is 2-12 hours, preferably 3-6 hours.

[0056] In embodiments of the present invention, monomer A is selected from styrene, monomer B is selected from octadecyl methacrylate and / or dodecyl methacrylate, and monomer C is selected from maleic anhydride. These are used as examples to illustrate the advantages of the present invention, but do not limit the scope of the invention. The styrene-alkyl methacrylate-alkyl maleic acid copolymer prepared using the aforementioned preferred monomers has a comb-like structure. Its side chain structure contains benzene rings, long alkyl chains, and polar groups. The long alkyl chains and benzene rings can form eutectics with paraffin molecules or adsorb paraffin crystals, inhibiting the aggregation and crystal growth of paraffin molecules. The copolymer molecules form a three-dimensional network structure, further inhibiting the aggregation of paraffin molecules. Furthermore, when copolymer molecules adsorb onto the surface of already formed paraffin crystals, the polar groups in their structure are exposed on the paraffin crystal surface, thereby changing the wettability of the paraffin crystals and further inhibiting the aggregation and crystal growth of paraffin crystals. The benzene rings and long alkyl chains in the copolymer molecules can also disperse the asphaltenes in crude oil, further improving the fluidity of crude oil and lowering its pour point.

[0057] In step (2) of this invention, there are no special requirements for the type of fatty alcohol. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the fatty alcohol is one or more of the straight-chain monohydric alcohols of C14-C28, preferably one or more of hexacosyl alcohol and diol.

[0058] In step (2) of the present invention, the molar ratio of fatty alcohol to monomer C can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the molar ratio of fatty alcohol to monomer C is 0.5-2:1.

[0059] In step (2) of this invention, there are no special requirements for the esterification reaction temperature. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the esterification reaction temperature is 120-140°C.

[0060] In step (2) of this invention, there are no special requirements for the esterification reaction pressure. Commonly used copolymerization reaction pressures are applicable to this invention. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the esterification reaction pressure is atmospheric pressure.

[0061] In step (2) of the present invention, the esterification reaction time can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the esterification reaction time is 3-6 hours.

[0062] In this invention, there are no special requirements for the instruments used in the polymerization and esterification reactions. Any instrument that can meet the requirements of this invention can be used in this invention. For example, the polymerization reaction can be carried out in a three-necked flask equipped with a thermometer, a constant speed stirrer and a reflux condenser.

[0063] In this invention, there are no special requirements for the heating and heat preservation instruments used in the polymerization and esterification reactions. Any instrument that can meet the requirements of this invention can be used in this invention, such as a constant temperature water bath.

[0064] This invention provides a styrene-alkyl methacrylate-alkyl maleic acid terpolymer prepared according to the preparation method of this invention. The terpolymer has a comb-like structure, and its side chain structure contains benzene rings, long alkyl chains, and polar groups. The long alkyl chains and benzene rings can form eutectics with paraffin molecules or adsorb paraffin crystals, inhibiting the aggregation and crystal growth of paraffin molecules. The copolymer molecules form a three-dimensional network structure, further inhibiting the aggregation of paraffin molecules. Furthermore, when copolymer molecules adsorb onto the surface of already formed paraffin crystals, the polar groups in their structure are exposed on the paraffin crystal surface, thereby changing the wettability of the paraffin crystals and further inhibiting the aggregation and crystal growth of paraffin crystals. The benzene rings and long alkyl chains in the copolymer molecules can also disperse asphaltenes in crude oil, further improving the fluidity of crude oil and lowering its pour point. Therefore, this terpolymer is very suitable for use as a paraffin-removing agent.

[0065] This invention provides the application of the terpolymer described herein as a wax remover.

[0066] The present invention provides a wax remover, which comprises the terpolymer described in the present invention and a solvent.

[0067] In the wax-removing agent of the present invention, the mass ratio of the terpolymer to the solvent can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the mass ratio of the terpolymer to the solvent is 1:2-9, preferably 1:3-6.

[0068] In the wax remover of the present invention, there are no special requirements for the solvent. The following is an illustrative description, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the solvent is one or more of xylene, gasoline, diesel, naphtha, solvent oil and C9 aromatics, preferably xylene.

[0069] In this invention, after preparing the styrene-alkyl methacrylate-alkyl maleic acid terpolymer, the terpolymer can be separated from the reaction solvent and further formulated into a wax remover. Alternatively, the terpolymer can be prepared directly from the mixture containing the terpolymer obtained after the polymerization reaction according to the mass ratio of the terpolymer to the solvent required for the wax remover.

[0070] In this invention, the flash point of the anti-wax agent is 65-70℃, and the freezing point is -25 to -19℃.

[0071] The wax remover and anti-wax agent provided by this invention features a high flash point and low pour point, making it suitable for use in extremely cold and low-temperature conditions. Furthermore, this wax remover and anti-wax agent can reduce the pour point and viscosity of crude oil, thus having a wide range of applications. Because the terpolymer in the wax remover and anti-wax agent has a comb-like structure, its side chain structure contains benzene rings, long alkyl chains, and polar groups. The long alkyl chains and benzene rings can form eutectics with paraffin molecules or adsorb paraffin crystals, inhibiting the aggregation and crystal growth of paraffin molecules. Moreover, the benzene rings and long alkyl chains in the copolymer molecules can disperse the asphaltenes in crude oil, further improving the fluidity of crude oil and lowering its pour point. Therefore, the wax remover and anti-wax agent has a certain wax-dissolving ability, capable of dissolving crystallized paraffin molecules, improving wax blockage, and exhibiting good wax removal and anti-wax effects.

[0072] This invention provides the application of the wax-removing and anti-waxing agent described herein in oil extraction.

[0073] In this invention, the crude oil comes from Changqing Oilfield, the natural gas condensate comes from Tarim Oilfield, and the shale oil comes from Fuling shale gas.

[0074] Example 1

[0075] First, weigh 0.5 mol of styrene, 1 mol of dodecyl methacrylate, and 1.5 mol of maleic anhydride into a three-necked flask. Then, add 300 mL of xylene and mix thoroughly. Next, add 0.005 mol of tert-butyl peroxide as an initiator, and then heat to 135 °C and react for 4 h to obtain a styrene-alkyl methacrylate-maleic anhydride copolymer. Then, add 2 mol of hexadecyl alcohol to the above product and react at 135 °C for 4 h to obtain a styrene-alkyl methacrylate-alkyl maleic acid copolymer.

[0076] Add 20 wt% of styrene-alkyl methacrylate-alkyl maleate copolymer to xylene and mix thoroughly to obtain styrene-alkyl methacrylate-alkyl maleate terpolymer dewaxing agent.

[0077] Example 2

[0078] First, weigh 0.5 mol of styrene, 1 mol of octadecyl methacrylate, and 1.5 mol of maleic anhydride into a three-necked flask. Then, add 300 mL of xylene and mix thoroughly. Next, add 0.005 mol of tert-butyl benzoate as an initiator, and then heat to 135 °C and react for 4 hours to obtain a styrene-alkyl methacrylate-maleic anhydride copolymer. Then, add 2 mol of docosyl alcohol to the above product and react at 135 °C for 4 hours to obtain a styrene-alkyl methacrylate-alkyl maleic acid copolymer.

[0079] Add 20 wt% of styrene-alkyl methacrylate-alkyl maleate copolymer to xylene and mix thoroughly to obtain styrene-alkyl methacrylate-alkyl maleate terpolymer dewaxing agent.

[0080] Example 3

[0081] First, weigh 0.5 mol of styrene, 1 mol of octadecyl methacrylate, and 1.5 mol of maleic anhydride into a three-necked flask. Then, add 300 mL of xylene and mix thoroughly. Next, add 0.005 mol of tert-butyl peroxide as an initiator, and then heat to 135 °C and react for 4 h to obtain a styrene-alkyl methacrylate-maleic anhydride copolymer. Then, add 2 mol of cetyl alcohol to the above product and react at 135 °C for 4 h to obtain a styrene-alkyl methacrylate-alkyl maleic acid copolymer.

[0082] Add 20 wt% of styrene-alkyl methacrylate-alkyl maleate copolymer to xylene and mix thoroughly to obtain styrene-alkyl methacrylate-alkyl maleate terpolymer dewaxing agent.

[0083] Example 4

[0084] First, weigh 0.5 mol of styrene, 1 mol of octadecyl methacrylate, and 1.5 mol of maleic anhydride into a three-necked flask. Then, add 300 mL of xylene and mix thoroughly. Next, add 0.005 mol of tert-butyl peroxide as an initiator, and then heat to 135 °C and react for 4 h to obtain a styrene-alkyl methacrylate-maleic anhydride copolymer. Then, add 2 mol of cetyl alcohol to the above product and react at 135 °C for 4 h to obtain a styrene-alkyl methacrylate-alkyl maleic acid copolymer.

[0085] Add 20 wt% of styrene-alkyl methacrylate-alkyl maleate copolymer to naphtha and mix evenly to obtain styrene-alkyl methacrylate-alkyl maleate terpolymer dewaxing agent.

[0086] Comparative Example 1

[0087] First, weigh 1 mol of octadecyl methacrylate and 1.5 mol of maleic anhydride into a three-necked flask, then add 300 mL of xylene and mix thoroughly. Next, add 0.005 mol of tert-butyl benzoate as an initiator, and then heat to 135 °C and react for 4 h to obtain an alkyl methacrylate-maleic anhydride copolymer. Then, add 2 mol of docosyl alcohol to the above product and react at 135 °C for 4 h to obtain the alkyl methacrylate-alkyl maleic acid copolymer.

[0088] Add 20 wt% of alkyl methacrylate-alkyl maleate copolymer to xylene and mix thoroughly to obtain alkyl methacrylate-alkyl maleate binary copolymer dewaxing agent.

[0089] Comparative Example 2

[0090] The wax remover is a commercially available product (Basoflux PI40).

[0091] Test Example 1

[0092] Referring to the standard SYT6300-2009 "Technical Conditions for Wax Removers and Inhibitors in Oil Production", the wax removal and wax prevention capabilities of the wax removers and inhibitors in Examples 1-4 and Comparative Examples 1-2 were characterized. The wax removal rate and wax prevention rate of each wax remover and inhibitor are listed in Table 1.

[0093] Table 1

[0094]

[0095]

[0096] As shown in Table 1, the paraffin wax remover provided by this invention can effectively eutectic or adsorb paraffin molecules, inhibiting the aggregation and growth of paraffin crystals, while also rapidly dissolving crystallized paraffin. The alkyl chain length of the terpolymer in the paraffin wax remover significantly affects the wax removal and prevention effect, and the benzene ring structure in the branched chain can also greatly promote the wax prevention effect.

[0097] Test Example 2

[0098] The anti-wax properties of the wax-removing agents in Examples 1-4 and Comparative Examples 1-2 in natural gas condensate were tested. The test method was as follows: the wax-removing agent was added to the natural gas condensate, placed in a pour point tester, cooled to -18°C, and maintained for 2 hours. The flow state of the condensate was observed. The results are listed in Table 2.

[0099] Table 2

[0100]

[0101] As shown in Table 2, the anti-wax agent provided by the present invention can effectively inhibit the precipitation of paraffin in natural gas condensate and prevent the growth of wax crystals, so that the condensate still has good fluidity under low temperature conditions.

[0102] Test Example 3

[0103] The flash point, pour point, and pour point lowering ability of the wax-removing agents in Examples 1-4 and Comparative Examples 1-2 were tested. Flash point was evaluated according to standard GB / T 261-2021 "Determination of Flash Point - Binsky-Martin Closed Cup Method," and pour point was evaluated according to GB / T 510-2018 "Petroleum Products - Determination of Pour Point." The results are listed in Table 3.

[0104] Table 3

[0105]

[0106] As shown in Table 3, the flash points of the wax removers and anti-wax agents provided by this invention are all 65°C and above, and the pour points are all -19°C and below. They can significantly reduce the pour points of crude oil, condensate oil and shale oil by 7 to 15°C.

[0107] The preferred embodiments of the present invention have been described above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A styrene-alkyl methacrylate-alkyl maleate terpolymer, characterized in that, The ternary copolymer comprises structural unit A, structural unit B, and structural unit C. The structural formula of structural unit A is: The structural formula of structural unit B is: The structural formula of structural unit C is: R1, R2, and R3 are each independently selected from straight-chain alkyl groups of C8-C30.

2. The terpolymer according to claim 1, characterized in that, R1, R2, and R3 are each independently selected from straight-chain alkyl groups of C14-C28.

3. The terpolymer according to claim 1 or 2, characterized in that, R1 is selected from one of C22 straight-chain alkyl groups and C18 straight-chain alkyl groups; and / or R2 is selected from one of C26 straight-chain alkyl groups and C22 straight-chain alkyl groups; and / or R3 is selected from one of C26 straight-chain alkyl groups and C22 straight-chain alkyl groups.

4. The terpolymer according to claim 1, characterized in that, Based on the total amount of the terpolymer, the content of structural unit A is 4-50 mol%, the content of structural unit B is 30-75 mol%, and the content of structural unit C is 33-66 mol%.

5. The terpolymer according to claim 1 or 4, characterized in that, Based on the total amount of the terpolymer, the content of structural unit A is 15-20 mol%, the content of structural unit B is 30-40 mol%, and the content of structural unit C is 45-55 mol%.

6. A method for preparing the terpolymer according to any one of claims 1-5, characterized in that, The method includes the following steps: (1) In the presence of a solvent and an initiator, monomer A, which provides structural unit A, monomer B, which provides structural unit B, and monomer C, which provides structural unit C, are subjected to a polymerization reaction. (2) Add fatty alcohols to the polymerization product to carry out esterification reaction.

7. The preparation method according to claim 6, characterized in that, The structural formula of monomer A is: The structural formula of monomer B is: The structural formula of monomer C is: In formula (2), R1 is defined in the same way as R1 in any one of claims 1-5, and the fatty alcohol is a fatty alcohol that provides groups R2 and R3.

8. The preparation method according to claim 6 or 7, characterized in that, In step (1), The molar ratio of monomer A, monomer B and monomer C is 0.1-1.5:0.5-2:0.5-1.

5.

9. The preparation method according to claim 8, characterized in that, In step (1), The molar ratio of monomer A, monomer B and monomer C is 0.1-0.5:0.5-1.5:1-1.

5.

10. The preparation method according to claim 6, characterized in that, In step (1), The solvent is one or more selected from toluene, xylene, trimethylbenzene, naphtha, solvent oil, and C9 aromatics; and / or The total monomer concentration in the solvent is 0.005-0.015 mol / mL.

11. The preparation method according to claim 6, characterized in that, In step (1), The initiator is one or more of azobisisobutyronitrile, benzoyl peroxide, and tert-butyl peroxide; and / or The molar ratio of initiator to total monomer is 1:300-1000.

12. The preparation method according to claim 6, characterized in that, In step (1), the polymerization reaction conditions include: Temperature is 110-150℃; and / or The time is 2-12 hours.

13. The preparation method according to claim 6, characterized in that, In step (2), The fatty alcohol is one or more of a C14-C28 straight-chain monohydric alcohol; and / or The molar ratio of fatty alcohol to monomer C is 0.5-2:

1.

14. The preparation method according to claim 6, characterized in that, In step (2), the esterification reaction conditions include: The temperature is 120-140℃; and / or The time is 3-6 hours.

15. The styrene-alkyl methacrylate-alkyl maleic acid terpolymer prepared by the preparation method according to any one of claims 6-14.

16. The use of the terpolymer according to any one of claims 1-5, 15 as a wax remover.

17. A wax remover, characterized in that, The wax remover comprises the terpolymer and solvent described in any one of claims 1-5 and 15.

18. The wax remover according to claim 17, characterized in that, The mass ratio of the terpolymer to the solvent is 1:2-9; and / or The solvent is one or more of xylene, trimethylbenzene, naphtha, solvent oil, and C9 aromatic hydrocarbons.

19. The application of the wax-removing agent according to claim 17 or 18 in oil extraction.

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