A shale oil wellbore wax cleaning and preventing agent and a preparation method thereof

Abstract

The present application belongs to the technical field of oil well wax removal and prevention, and relates to a shale oil well shaft wax removal and prevention agent and a preparation method thereof. The shale oil well shaft wax removal and prevention agent comprises the following raw materials in percentage by mass: 40-55% of an oily solvent, 1-3% of a cosolvent, 1-2% of an imidazole double-trifluoromethylsulfonylimide salt, 10-20% of a wax crystal modifier, 3-5% of an emulsifier, 1-2% of an alkaline adjusting agent, and 25-35% of water, with the sum of the percentage by mass of each raw material being 100%; the wax crystal modifier is prepared by copolymerizing (methyl) acrylic C12-C16 ester, (methyl) acrylic C1-C3 ester and (methyl) acryloyl chloride, and then reacting with C20-C30 alkyl alcohol. The wax crystal modifier in the present application has long-mid-short branched chains, and cooperates with the imidazole double-trifluoromethylsulfonylimide salt to improve the wax removal effect and low-temperature fluidity, thereby achieving high-efficiency wax removal and prevention effect and still maintaining good wax removal and prevention effect at low temperatures.

Description

Technical Field

[0001] This invention belongs to the field of oil well wax removal and prevention technology, specifically relating to a wax removal and prevention agent for shale oil wells and its preparation method. Background Technology

[0002] Shale oil, stored in the micro- and nano-scale pores of shale formations, is abundant and has become an important strategic resource for oilfield development. Compared with conventional crude oil, shale oil generally contains more paraffin wax. Therefore, during wellbore lifting, as temperature and pressure decrease, wax molecules are more likely to precipitate and nucleate from the crude oil, resulting in more severe wax deposition. The deposited wax crystals adhere to the inner wall of the wellbore, causing blockage of oil and gas migration channels, reduced oil and gas production, or even production stoppage. Therefore, the control of wax deposition in shale oil wellbores requires higher standards.

[0003] Currently, wax deposition control can be divided into two aspects: wax removal and wax prevention. Wax removal and prevention agents that combine both functions represent a current research trend. These agents can effectively extend the wax removal cycle and significantly improve the efficiency of wax removal and prevention operations by prioritizing prevention while combining prevention with removal. Commonly used wax removal and prevention technologies can be categorized into three types: physical, chemical, and biological methods. Among these, chemical wax removal and prevention methods have advantages such as simple dosing methods, good wax removal and prevention effects, and wide applicability, making them the most widely used wax removal and prevention methods currently. Chemical wax removers are mainly classified into oil-based, water-based, and emulsion-type wax removers. Oil-based wax removers mostly use benzene, toluene, and xylene as organic solvents, and their wax-removing ability is generally strong, but they are flammable and have a certain degree of toxicity. Water-based wax removers are more environmentally friendly and safer, but their wax-removing efficiency is generally lower. Emulsion-type wax removers have a wax-removing effect similar to oil-based wax removers, but their safety is significantly improved, so they have more application prospects. During use, the temperature of crude oil is used to break the emulsion of the injected emulsion-type wax remover, releasing the oily active ingredients encapsulated in water to achieve the wax-removing effect.

[0004] Current wax-removing agents, regardless of type, all suffer from poor low-temperature performance. CN112195019A discloses an emulsion-type wax-removing agent, which is composed of an oil phase solvent, an emulsifier, a co-solvent, an alkalinity regulator, and water. The oil phase solvent is a mixture of petroleum ether, cyclohexane, and n-heptane in a volume ratio of 1:0.5~1.5:0.05~0.3. The emulsifier is glyceryl monostearate and / or sodium stearoyl lactylate. The co-solvent is diethylene glycol butyl ether and / or diethylene glycol monomethyl ether. The alkalinity regulator is sodium oxalate and sodium citrate. This emulsion-type wax-removing agent is free of chlorine and sulfur, which improves the toxicity of wax-removing agents. It has both wax-preventing and wax-removing effects. However, its wax dissolution rate is poor, and it does not solve the problem of poor low-temperature performance of wax-preventing agents. CN118652370A discloses a hyperbranched polymer wax inhibitor and its preparation method. The method involves dissolving long-chain acrylate monomers, maleic anhydride, 4-allyl anisole, short-chain ester monomers, and branched monomers in xylene, adding 0.1-1% of the initiator benzoyl peroxide, and reacting the mixture at 70-90°C with stirring for 4-8 hours to obtain the hyperbranched polymer wax inhibitor. The wax inhibitor effect is significantly improved, but the drawback of poor low-temperature performance of the wax inhibitor is still not solved. Summary of the Invention

[0005] The purpose of this invention is to provide a wax removal and prevention agent for shale oil wellbores, so as to solve the problem that the existing wax removal and prevention agents have poor wax removal and prevention performance, especially the wax removal and prevention performance decreases at low temperatures.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A wax remover for shale oil wellbores, comprising the following raw materials by weight percentage:

[0008] Oily solvent 40-55%,

[0009] 1-3% cosolvent

[0010] Imidazole ditrifluoromethanesulfonyl imide salts 1-2%,

[0011] Wax crystal improver 10-20%,

[0012] Emulsifier 3-5%,

[0013] Alkalinity regulator 1~2%,

[0014] Water 25-35%,

[0015] The sum of the mass percentages of the above raw materials is 100%;

[0016] The wax crystal modifier is prepared by copolymerizing (meth)acrylate C12-C16 ester, (meth)acrylate C1-C3 ester, and (meth)acryloyl chloride in a molar ratio of 1:(0.2~0.3):(0.1~0.2) and then esterifying it with C20-C30 alkyl alcohol; the molar ratio of (meth)acryloyl chloride to C20-C30 alkyl alcohol is 1:1~1.1.

[0017] Further, the imidazole bis(trifluoromethanesulfonyl)imide salt is selected from at least one of 1-butyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, 1-hexyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, and 1-octyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt; preferably 1-butyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt.

[0018] Preferably, in the raw materials for preparing the wax crystal modifier, the molar ratio of (meth)acrylate C12-C16 ester, (meth)acrylate C1-C3 ester, and (meth)acryloyl chloride is 1:(0.25~0.3):(0.15~0.2).

[0019] Further, the (meth)acrylate C12-C16 ester is selected from at least one of (meth)acrylate dodecyl ester, (meth)acrylate tetradecyl ester, and (meth)acrylate hexadecyl ester; the (meth)acrylate C1-C3 ester is selected from at least one of (meth)acrylate methyl ester, (meth)acrylate ethyl ester, and (meth)acrylate propyl ester; the C20-C30 alkyl alcohol is selected from at least one of n-eicosanool, n-docosanool, n-tetracosanool, n-hexacosanool, n-octacosanool, and n-triacosanool, preferably n-hexacosanool.

[0020] Further, the preparation method of the wax crystal modifier is as follows: C12-C16 ester of (meth)acrylate, C1-C3 ester of (meth)acrylate, (meth)acryloyl chloride and initiator are dissolved together in a solvent, and copolymerized at 70-90°C for 4-8 hours under a protective atmosphere with stirring; then C20-C30 alkyl alcohol is added, and the reaction is continued at 100-130°C for 1-3 hours under a protective atmosphere; after the reaction is completed, the low-boiling substances are removed by vacuum distillation to obtain the wax crystal modifier.

[0021] Furthermore, the initiator is at least one of benzoyl peroxide, azobisisobutyronitrile, and dicumyl peroxide, and the amount of initiator used is 0.1-0.3% of the total mass of (meth)acrylate C12-C16 ester, (meth)acrylate C1-C3 ester, and (meth)acryloyl chloride; the solvent is at least one of N,N′-dimethylacetamide (DMAC), N,N′-dimethylformamide (DMF), and N-methylpyrrolidone (NMP); the protective atmosphere is nitrogen and / or argon; and the conditions for vacuum distillation are: 140-160°C, vacuum degree -0.1MPa to -0.01MPa for 1-2 hours.

[0022] Furthermore, the oily solvent is a mixture of petroleum ether and C6-C9 aromatic hydrocarbons in a mass ratio of 1:2 to 3; the C6-C9 aromatic hydrocarbons are at least one of benzene, toluene, xylene, and trimethylbenzene.

[0023] Furthermore, the co-solvent is at least one of diethylene glycol ethyl ether, diethylene glycol monobutyl ether, and diethylene glycol monomethyl ether.

[0024] Furthermore, the emulsifier is at least one of glyceryl monostearate and fatty alcohol polyoxyethylene heptaether.

[0025] Furthermore, the alkalinity regulator is at least one of sodium hydroxide, potassium hydroxide, sodium citrate, and potassium citrate.

[0026] Secondly, the present invention also provides a method for preparing the above-mentioned wax remover and anti-wax agent for shale oil wellbores, comprising the following steps: mixing and dissolving an alkaline regulator, an emulsifier and water to obtain a mixed solution; mixing an oily solvent, a co-solvent, an imidazole bis(trifluoromethanesulfonyl)imide salt, a wax crystal modifier and the mixed solution, and emulsifying at high speed to obtain a wax remover and anti-wax agent for shale oil wellbores.

[0027] Furthermore, the emulsification conditions at high speed are: emulsification at 1000~1500 r / min for 30~60 min.

[0028] The copolymer formed by copolymerizing (meth)acrylate C12-C16 ester, (meth)acrylate C1-C3 ester, and (meth)acryloyl chloride in this invention has a branched structure. The C1-C3 ester group in the (meth)acrylate C1-C3 ester provides short branches, the C12-C16 ester group in the (meth)acrylate C12-C16 ester provides medium-length branches, and the (meth)acryloyl chloride provides active acrylic chloride groups. Then, the acrylic chloride groups undergo an esterification reaction with C20-C30 alkyl alcohols to introduce long alkane chains (C20-C30) into the copolymer, forming long alkane branches containing ester groups. That is, the final wax crystal modifier has a "long-medium-short" tertiary branched structure, and each branch has a polar ester group. Short-chain branched alkane has a shorter chain length and a relatively higher density of polar ester groups, which allows it to preferentially and effectively adsorb onto the surface of precipitated micro-wax crystal nuclei or the active growth points of wax crystals, thereby effectively inhibiting further growth and aggregation of wax crystals. Medium-chain branched alkane has a chain length similar to that of medium-carbon wax molecules in shale oil, with good compatibility. It can embed itself into the growing wax crystal lattice through "eutectic action," causing lattice distortion and disrupting the regular arrangement of wax crystals, preventing them from forming a dense and robust three-dimensional network structure. This makes the wax crystals loose, soft, and easily washed away by oil flow. Long-chain branched alkane chains are extremely similar in structure to high-carbon paraffin (C20 and above), with excellent compatibility. They can penetrate deeper into the interior of wax crystals through eutectic action, greatly distorting the wax crystal morphology. With its huge steric hindrance effect, it effectively prevents the mutual adhesion, aggregation, and deposition between wax crystals. At the same time, the non-polar part of the long chain extends outward, which can also improve the wettability of the deposits and the well pipe wall, making them easier to peel off. In summary, the synergistic effect of the "long-medium-short" branches in the wax crystal modifier effectively prevents waxing.

[0029] Imidazole-based bis(trifluoromethanesulfonyl)imide salts are ionic liquids with good thermal stability and good solubility for organic matter, which can act as a "solvent" to improve the wax removal effect. At the same time, imidazole-based bis(trifluoromethanesulfonyl)imide salts can improve low-temperature fluidity, so that the wax crystal modifier can also effectively diffuse and act on the wax crystal at low temperatures.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. The wax crystal modifier in this invention has "long-medium-short" branches. The three branches work synergistically to effectively inhibit wax deposition and achieve excellent wax prevention. At the same time, imidazole bis(trifluoromethanesulfonyl)imide salt can improve the wax removal effect and low-temperature fluidity. Its combined action with the wax crystal modifier achieves efficient control of wax deposition in shale oil wellbore, especially maintaining a good wax removal and prevention effect at low temperatures.

[0032] 2. The wax remover and anti-wax agent for shale oil wellbores of the present invention is an emulsion type, which is safer to use; and it has good wax removal and anti-wax effects even at a low dosage. At an addition of 200 ppm, its wax dissolution rate at 60°C is as high as 0.13 g or more, and its wax prevention rate is as high as 90% or more; at a low temperature of 30°C, its wax dissolution rate is also as high as 0.07 g or more, and its wax prevention rate is as high as 70% or more. Detailed Implementation

[0033] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0034] Unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0035] Preparation of wax crystal modifier

[0036] Preparation Example 1

[0037] 1 mol tetradecyl acrylate, 0.25 mol ethyl methacrylate, and 0.15 mol methacryloyl chloride were dissolved together in DMF. Then, benzoyl peroxide (0.1% of the total mass of tetradecyl acrylate, ethyl methacrylate, and methacryloyl chloride) was added to form a mixed solution. The mixture was copolymerized at 80°C under a nitrogen atmosphere with a stirring rate of 300 r / min for 6 h. Then, 0.16 mol n-hexadecanoic acid was added, and the reaction was continued at 120°C under a nitrogen atmosphere for 2 h. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of -0.1 MPa for 1 h to remove low-boiling substances, thus obtaining wax crystal modifier a.

[0038] Preparation Example 2

[0039] The rest is the same as in Preparation Example 1, except that the molar ratio of the raw materials is different, specifically:

[0040] 1 mol tetradecyl acrylate, 0.2 mol ethyl methacrylate, and 0.1 mol methacryloyl chloride were dissolved together in DMF, and then benzoyl peroxide (0.1% of the total mass of tetradecyl acrylate, ethyl methacrylate, and methacryloyl chloride) was added to form a mixed solution. The mixture was copolymerized at 80°C under a nitrogen atmosphere with a stirring rate of 300 r / min for 6 h. Then, 0.1 mol n-hexadecanoic acid was added, and the reaction was continued at 120°C under a nitrogen atmosphere for 2 h. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of -0.1 MPa for 1 h to remove low-boiling substances, thus obtaining wax crystal modifier b.

[0041] Preparation Example 3

[0042] The rest is the same as in Preparation Example 1, except that the molar ratio of the raw materials is different, specifically:

[0043] 1 mol of tetradecyl acrylate, 0.3 mol of ethyl methacrylate, and 0.2 mol of methacryloyl chloride were dissolved together in DMF. Then, benzoyl peroxide (0.1% of the total mass of tetradecyl acrylate, ethyl methacrylate, and methacryloyl chloride) was added to form a mixed solution. The mixture was copolymerized at 80°C for 6 hours under a nitrogen atmosphere with a stirring rate of 300 r / min. Then, 0.22 mol of n-hexadecanoic acid alcohol was added, and the reaction was continued at 120°C for 2 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of -0.1 MPa for 1 hour to remove low-boiling substances, thus obtaining wax crystal modifier c.

[0044] Preparation Example 4

[0045] The rest is the same as in Preparation Example 1, except that the types of raw materials are different, specifically:

[0046] 1 mol of dodecyl acrylate, 0.25 mol of methyl methacrylate, and 0.15 mol of methacryloyl chloride were dissolved together in NMP. Then, azobisisobutyronitrile (0.3% of the total mass of dodecyl acrylate, methyl methacrylate, and methacryloyl chloride) was added to form a mixed solution. The copolymerization reaction was carried out at 70°C for 8 h under a nitrogen atmosphere with a stirring rate of 300 r / min. Then, 0.16 mol of n-eicosanol was added, and the reaction was continued at 100°C for 3 h under a nitrogen atmosphere. After the reaction was completed, the mixture was evacuated at 140°C and a vacuum of -0.1 MPa for 1 h to remove low-boiling substances, thus obtaining wax crystal modifier d.

[0047] Preparation Example 5

[0048] The rest is the same as in Preparation Example 1, except that the types of raw materials are different, specifically:

[0049] 1 mol of hexadecyl acrylate, 0.25 mol of propyl methacrylate, and 0.15 mol of methacryloyl chloride were dissolved together in NMP. Then, dicumyl peroxide (0.2% of the total mass of hexadecyl acrylate, propyl methacrylate, and methacryloyl chloride) was added to form a mixed solution. The mixture was copolymerized at 90°C for 4 hours under a nitrogen atmosphere with a stirring rate of 300 r / min. Then, 0.16 mol of n-triacontanol was added, and the reaction was continued at 100°C for 3 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was evacuated at 160°C and a vacuum of -0.1 MPa for 2 hours to remove low-boiling substances, thus obtaining wax crystal modifier e.

[0050] Comparative Preparation Example 1

[0051] The difference from Preparation Example 1 is that: methacryloyl chloride and n-hexadecanoic acid alcohol are not used; that is, the wax crystal modifier is a copolymer of tetradecyl acrylate and ethyl methacrylate, which does not contain long branches, specifically:

[0052] 1 mol of tetradecyl acrylate and 0.25 mol of ethyl methacrylate were dissolved together in DMF, and then benzoyl peroxide (0.1% of the total mass of tetradecyl acrylate and ethyl methacrylate) was added to form a mixed solution. The mixture was copolymerized at 80°C for 6 hours under a nitrogen atmosphere with a stirring rate of 300 r / min. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of -0.1 MPa for 1 hour to remove low-boiling substances, thus obtaining the wax crystal modifier f.

[0053] Comparative Preparation Example 2

[0054] The difference from Preparation Example 1 is that ethyl methacrylate is not used, meaning the wax crystal modifier does not contain short-chain branches. Specifically:

[0055] 1 mol of tetradecyl acrylate and 0.15 mol of methacryl chloride were dissolved together in DMF, and then benzoyl peroxide (0.1% of the total mass of tetradecyl acrylate and methacryl chloride) was added to form a mixed solution. The copolymerization reaction was carried out at 80°C for 6 h under a nitrogen atmosphere with a stirring rate of 300 r / min. Then 0.16 mol of n-hexadecanoic acid alcohol was added, and the reaction was continued at 120°C for 2 h under a nitrogen atmosphere. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of -0.1 MPa for 1 h to remove low-boiling substances, thus obtaining g of wax crystal modifier.

[0056] Comparative preparation example 3

[0057] The difference from Preparation Example 1 is that tetradecyl acrylate is not used, meaning the wax crystal modifier does not contain medium-chain branches. Specifically:

[0058] 0.25 mol of ethyl methacrylate and 0.15 mol of methacryloyl chloride were dissolved together in DMF, and then benzoyl peroxide (0.1% of the total mass of ethyl methacrylate and methacryloyl chloride) was added to form a mixed solution. The mixture was copolymerized at 80 °C for 6 h under a nitrogen atmosphere with a stirring rate of 300 r / min. Then, 0.16 mol of n-hexadecanoic acid alcohol was added, and the reaction was continued at 120 °C for 2 h under a nitrogen atmosphere. After the reaction was completed, the mixture was evacuated at 150 °C and a vacuum of -0.1 MPa for 1 h to remove low-boiling substances, thus obtaining the wax crystal modifier h. Example 1

[0059] A wax remover for shale oil wellbores, comprising the following raw materials by weight percentage:

[0060] Oily solvent 48%,

[0061] 2% diethylene glycol monobutyl ether

[0062] 1% butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt

[0063] Wax crystal modifier a 15%,

[0064] 4% fatty alcohol polyoxyethylene heptaether

[0065] 1% sodium citrate

[0066] Water 29%,

[0067] The oily solvent is a mixture of petroleum ether and xylene in a mass ratio of 1:2;

[0068] The above raw materials were prepared into a wax remover and anti-wax agent for shale oil wellbores according to the following steps: Sodium citrate, fatty alcohol polyoxyethylene heptaether, and water were mixed and dissolved to obtain a mixed solution; an oily solvent, diethylene glycol monobutyl ether, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and wax crystal modifier a were mixed with the mixed solution and emulsified at 1200 r / min for 40 min to obtain the wax remover and anti-wax agent for shale oil wellbores. Example 2

[0069] The rest is the same as in Example 1, except that wax crystal modifier b prepared in Preparation Example 2 is used instead of wax crystal modifier a. Example 3

[0070] The rest is the same as in Example 1, except that wax crystal modifier c prepared in Preparation Example 3 is used instead of wax crystal modifier a. Example 4

[0071] The rest is the same as in Example 1, except that wax crystal modifier d prepared in Preparation Example 4 is used instead of wax crystal modifier a. Example 5

[0072] The rest is the same as in Example 1, except that wax crystal modifier e prepared in Preparation Example 5 is used instead of wax crystal modifier a. Example 6

[0073] Everything else is the same as in Example 1, except that the types of raw materials are different, specifically:

[0074] Oily solvent 48%,

[0075] 2% diethylene glycol ethyl ether

[0076] 1% 1-Octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt

[0077] Wax crystal modifier a 15%,

[0078] 4% glyceryl monostearate

[0079] 1% potassium hydroxide

[0080] Water 29%,

[0081] The oily solvent is a mixture of petroleum ether and tricresylbenzene in a mass ratio of 1:2. Example 7

[0082] Everything else is the same as in Example 1, except that the mass ratio of the raw materials is different, specifically:

[0083] 40% oil-based solvent

[0084] Diethylene glycol monobutyl ether 3%,

[0085] 1.5% butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt

[0086] Wax crystal modifier a 20%,

[0087] 3% fatty alcohol polyoxyethylene heptaether

[0088] Sodium citrate 2%,

[0089] Water 30.5%,

[0090] The oily solvent is a mixture of petroleum ether and xylene in a mass ratio of 1:3. Example 8

[0091] Everything else is the same as in Example 1, except that the mass ratio of the raw materials is different, specifically:

[0092] 55% oil-based solvent

[0093] 1% diethylene glycol monobutyl ether

[0094] 2% of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt

[0095] Wax crystal modifier a 10%,

[0096] 5% fatty alcohol polyoxyethylene heptaether

[0097] Sodium citrate 1.5%,

[0098] Water 25.5%,

[0099] The oily solvent is a mixture of petroleum ether and xylene in a mass ratio of 1:3.

[0100] Comparative Example 1

[0101] The rest is the same as in Example 1, except that wax crystal modifier f prepared in Comparative Preparation Example 1 is used instead of wax crystal modifier a.

[0102] Comparative Example 2

[0103] The rest is the same as in Example 1, except that wax crystal modifier g prepared in Comparative Preparation Example 2 is used instead of wax crystal modifier a.

[0104] Comparative Example 3

[0105] The rest is the same as in Example 1, except that wax crystal modifier h prepared in Comparative Preparation Example 3 is used instead of wax crystal modifier a.

[0106] Comparative Example 4

[0107] The rest is the same as in Example 1, except that 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is not used, and correspondingly, the mass percentage of diethylene glycol monobutyl ether is 3%.

[0108] Testing and Analysis

[0109] According to the test methods in "SY / T 6300-2009 Technical Conditions for Dewaxing and Wax-Inhibiting Agents for Oil Production", the wax dissolution rate and wax inhibition rate of the dewaxing and wax-inhibiting agents prepared in the examples and comparative examples were tested, as follows:

[0110] Wax dissolving rate test: 15 mL of the prepared wax-removing agent was added to the wax dissolving test apparatus. The water bath was used for temperature control. After the solution reached a constant temperature, wax ball No. 58 was placed into the wax-removing agent solution, and the time t required for the wax ball to completely dissolve was recorded at different temperatures (30℃, 60℃). The wax dissolving rate V was calculated using the formula: V = m / t, where V is the wax dissolving rate (g / min), m is the mass of the wax ball (g), and t is the time required for the wax ball to completely dissolve (min). The specific test results are shown in Table 1.

[0111] Wax prevention rate test: The wax prevention rate of the prepared wax inhibitor was tested at different temperatures (30℃ and 60℃) in shale crude oil from Daqing Oilfield (the shale crude oil has a paraffin content of 28.4% and a wax precipitation point of 28.9℃) using the circulating wax deposition tube method. The addition amount of the wax inhibitor was 200 ppm. The wax prevention rate E was calculated using the formula E = (m1 - m0) / m1, where E is the wax prevention rate (%), m1 is the amount of wax deposited in the oil sample without the wax inhibitor (g), and m0 is the amount of wax deposited in the oil sample with the wax inhibitor (g). The specific test results are shown in Table 1.

[0112]

[0113] As shown in Table 1, temperature has a significant impact on the wax dissolution rate and the wax prevention rate. Higher temperatures lead to a faster wax dissolution rate, indicating that higher temperatures result in faster molecular movement on the wax crystal surface, allowing the wax crystals to dissolve better in the wax crystal modifier. The solubilizing effect of imidazole bis(trifluoromethanesulfonyl)imide salt further enhances the wax crystal dissolution rate. Temperature is also a major factor affecting paraffin deposition; lower temperatures facilitate wax formation. Table 1 shows that even at a relatively low temperature of 30°C, the wax-preventing agent prepared in this embodiment of the invention exhibits a high wax prevention rate. This is mainly attributed to the "long-medium-short" tertiary branched chain structure of the wax crystal modifier, which allows for better adsorption to the solid-liquid interface, playing a eutectic role in the wax prevention process, increasing its compatibility with the oil sample, and strengthening the wax prevention effect. Simultaneously, its structure contains highly polar ester groups, which can synergistically interact with asphaltenes and gums in crude oil, preventing further wax crystal growth.

[0114] In summary, as shown in Table 1, the wax-removing and anti-wax agents prepared in the embodiments of the present invention exhibit high wax dissolution rates and wax prevention rates at both low temperatures (30°C) and high temperatures (60°C). The wax crystal modifiers in Comparative Examples 1-3, which do not simultaneously possess a specific "long-medium-short" tertiary branched structure, have slightly lower wax dissolution rates and significantly poorer wax prevention rates. Comparative Example 4, which does not use imidazole-based bis(trifluoromethanesulfonyl)imide salts, has significantly lower wax dissolution rates and also poorer wax prevention rates.

Claims

1. A wax remover and anti-wax agent for shale oil wellbores, characterized in that, Including the following percentages by weight of raw materials: Oily solvent 40-55%, 1-3% cosolvent Imidazole ditrifluoromethanesulfonyl imide salts 1-2%, Wax crystal improver 10-20%, Emulsifier 3-5%, Alkalinity regulator 1~2%, Water 25-35%, The sum of the mass percentages of the above raw materials is 100%; The wax crystal modifier is prepared by copolymerizing (meth)acrylate C12-C16 ester, (meth)acrylate C1-C3 ester, and (meth)acryloyl chloride in a molar ratio of 1:(0.2~0.3):(0.1~0.2) and then esterifying it with C20-C30 alkyl alcohol; the molar ratio of (meth)acryloyl chloride to C20-C30 alkyl alcohol is 1:1~1.

1.

2. The wax remover and anti-wax agent for shale oil wellbores according to claim 1, characterized in that, The imidazole bis(trifluoromethanesulfonyl)imide salt is selected from at least one of 1-butyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, 1-hexyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, and 1-octyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt.

3. The wax remover / anti-wax agent for shale oil wellbores according to claim 2, characterized in that, The imidazole bis(trifluoromethanesulfonyl)imide salt is 1-butyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt.

4. The wax remover and anti-wax agent for shale oil wellbores according to claim 1, characterized in that, In the raw materials for preparing the wax crystal modifier, the molar ratio of (meth)acrylate C12-C16 ester, (meth)acrylate C1-C3 ester, and (meth)acryloyl chloride is 1:(0.25~0.3):(0.15~0.2).

5. The wax remover and anti-wax agent for shale oil wellbores according to claim 1, characterized in that, The (meth)acrylate C12-C16 ester is selected from at least one of (meth)acrylate dodecyl ester, (meth)acrylate tetradecyl ester, and (meth)acrylate hexadecyl ester; the (meth)acrylate C1-C3 ester is selected from at least one of (meth)acrylate methyl ester, (meth)acrylate ethyl ester, and (meth)acrylate propyl ester; the C20-C30 alkyl alcohol is selected from at least one of n-eicosanool, n-dococosanool, n-hexacosanool, n-octacosanool, and n-triacosanool.

6. The wax remover and anti-wax agent for shale oil wellbores according to claim 5, characterized in that, The C20-C30 alkyl alcohol is n-hexacosanol.

7. The wax remover and anti-wax agent for shale oil wellbores according to claim 1, characterized in that, The preparation method of the wax crystal modifier is as follows: C12-C16 ester of (meth)acrylate, C1-C3 ester of (meth)acrylate, (meth)acryloyl chloride and initiator are dissolved together in a solvent, and copolymerized at 70-90°C for 4-8 hours under stirring in a protective atmosphere; then C20-C30 alkyl alcohol is added, and the reaction is continued at 100-130°C for 1-3 hours in a protective atmosphere; after the reaction is completed, the low-boiling substances are removed by vacuum distillation to obtain the wax crystal modifier.

8. The wax remover and anti-wax agent for shale oil wellbores according to claim 7, characterized in that, The initiator is at least one of benzoyl peroxide, azobisisobutyronitrile, and dicumyl peroxide, and the amount of initiator used is 0.1-0.3% of the total mass of (meth)acrylate C12-C16 ester, (meth)acrylate C1-C3 ester, and (meth)acryloyl chloride; the solvent is at least one of N,N′-dimethylacetamide, N,N′-dimethylformamide, and N-methylpyrrolidone; the protective atmosphere is nitrogen and / or argon; the conditions for vacuum distillation are: 140-160℃, vacuum degree -0.1MPa to -0.01MPa for 1-2 hours.

9. The wax remover and anti-wax agent for shale oil wellbores according to claim 1, characterized in that, The oily solvent is a mixture of petroleum ether and C6-C9 aromatic hydrocarbons in a mass ratio of 1:2-3; the C6-C9 aromatic hydrocarbons are at least one selected from benzene, toluene, xylene, and trimethylbenzene; and / or, The co-solvent is at least one selected from diethylene glycol ethyl ether, diethylene glycol monobutyl ether, and diethylene glycol monomethyl ether; and / or The emulsifier is at least one of glyceryl monostearate and fatty alcohol polyoxyethylene heptaether; and / or The alkalinity regulator is at least one of sodium hydroxide, potassium hydroxide, sodium citrate, and potassium citrate.

10. The method for preparing the wax-removing agent according to any one of claims 1-9, characterized in that, The process includes the following steps: mixing and dissolving an alkaline regulator, an emulsifier, and water to obtain a mixed solution; mixing an oily solvent, a co-solvent, an imidazole bis(trifluoromethanesulfonyl)imide salt, a wax crystal modifier, and the mixed solution, and emulsifying at high speed to obtain a wax-removing and anti-wax agent for shale oil wellbores.

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