Viscosity reducer for deep low-permeability heavy oil reservoir exploitation and preparation method and use thereof

Abstract

The application discloses a viscosity reducer for exploitation of deep low-permeability heavy oil reservoirs and a preparation method and application thereof. The preparation method comprises the following steps: (1) under the conditions of existence of a solvent and a catalyst and heating, 4-halogenophthalic anhydride and glycol compounds are subjected to nucleophilic addition reaction under the atmosphere of nitrogen or inert gas to obtain a mixed solution containing intermediate A; (2) diazomethane is introduced into the mixed solution containing intermediate A, and diazomethane and intermediate A are subjected to nucleophilic transfer reaction to obtain a mixed solution containing intermediate B; (3) polyethylene glycol or dimethylaluminum is added into the mixed solution containing intermediate B, and after stirring, sodium sulfite is added, and under the condition of heating, intermediate B and sodium sulfite are subjected to sulfonation reaction of nucleophilic displacement, and after reaction, the viscosity reducer is obtained through post-treatment. The application further discloses application of the viscosity reducer as a displacement flow-increasing viscosity reducer in exploitation of deep low-permeability heavy oil reservoirs.

Description

Technical Field

[0001] This invention belongs to the field of chemistry and relates to a viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs, its preparation method, and its uses. Background Technology

[0002] With the continuous exploitation of conventional oil and gas resources and the continuous progress of oil and gas exploration and development theories and technologies, the proportion of deep, low-permeability heavy oil in oil and gas resources has been increasing year by year, and it has become the main potential for oil development.

[0003] The exploration and development potential of deep, low-permeability heavy oil is enormous. Taking Shengli Oilfield as an example, the reserves of deep, low-permeability heavy oil in the eastern part of Shengli Oilfield are about 96.29 million tons, accounting for about 30% of the untapped heavy oil resources. It is the main battleground for the construction and production of new heavy oil areas.

[0004] Due to the deep burial depth and low permeability, steam injection extraction is of poor quality, and the effects of early-stage thermal recovery and post-fracture thermal recovery are poor. Therefore, a high-pressure composite displacement development method is adopted to solve the problems of high viscosity and low permeability of heavy oil. The key to the high-pressure composite displacement development method is the urgent need for a viscosity reducer suitable for deep, low-permeability heavy oil reservoirs to improve the washing ability and displacement effect of the viscosity reducer.

[0005] Chinese invention patent application CN107033866 A discloses a heavy oil emulsifying viscosity reducer, its preparation method, and its uses. This heavy oil emulsifying viscosity reducer contains sodium hydroxide or sodium bicarbonate, as well as alkylphenol polyoxyethylene polyoxypropylene alcohol ether, n-butanol, and dibenzyl sorbitol, with the balance being water. This heavy oil emulsifying viscosity reducer has low manufacturing cost, a viscosity reduction rate exceeding 98%, and can automatically demulsify at high temperatures after extraction. It also exhibits good salt resistance, making it particularly suitable for formation water with a salinity as high as 25000 mg / L. However, the technical solution in this patent application mainly involves a compounding of emulsifying viscosity reducers and does not relate to the preparation of a displacement, drag-reducing, and viscosity-reducing agent.

[0006] Chinese invention patent application CN117701265A relates to a viscosity-reducing and displacement agent for heavy oil, its preparation method, and its application. The preparation method is as follows: Nonylphenol, 4-piperidinecarboxylic acid, formaldehyde, and water are added to a four-necked flask, stirred, and heated to reflux until the reaction is complete. Cooling water is introduced, and unreacted raw materials are distilled off under normal pressure. The mixture is cooled to room temperature, and the pH is adjusted. The liquid is transferred to an autoclave, purged with nitrogen, stirred, and heated. Ethylene oxide is introduced, and nitrogen is introduced to pressurize the reactor. The temperature is continued to rise. After the reaction, the mixture is cooled to room temperature to obtain a water-containing crude product. The water-containing crude product is separated by silica gel chromatography to obtain a deep yellow viscous liquid, which is the viscosity-reducing and displacement agent. However, the above-mentioned viscosity-reducing and displacement agent for heavy oil is only suitable for medium-to-high permeability heavy oil reservoirs. In the exploitation of deep, low-permeability reservoirs, the high pressure and high salinity lead to a more compact asphaltene structure, making displacement difficult and reducing the oil washing capacity. Therefore, it is not suitable for the exploitation and application of deep, low-permeability reservoirs.

[0007] Chinese invention patent CN113136190B relates to a heavy oil viscosity-reducing and displacement agent with regulating and displacing properties, composed of 35-50 parts tallolacamide hydroxysulfonate betaine, 15-30 parts nonionic surfactant, and 20-50 parts deionized water. Tallolacamide hydroxysulfonate betaine is prepared from tallolacamide propyl dimethylamine and sodium 3-chloro-2-hydroxypropyl sulfonate. The main agent is tallolacamide hydroxysulfonate betaine. The system exhibits good emulsifying properties, high interfacial activity, a certain thickening ability, high temperature and high salt resistance, and is environmentally friendly. However, the above-mentioned heavy oil viscosity-reducing and displacement agent is only suitable for medium-to-high permeability heavy oil reservoirs. In the exploitation of deep, low-permeability reservoirs, the high pressure and high salinity lead to a more compact asphaltene structure, making displacement more difficult. Therefore, it is not suitable for the exploitation and application of deep, low-permeability reservoirs.

[0008] In summary, existing viscosity reducers are generally suitable for medium- to high-permeability heavy oil reservoirs, but are not used for deep, low-permeability reservoirs. Given the increasing proportion of controlled reserves in deep, low-permeability reservoirs, there is an urgent need to develop a displacement-enhancing viscosity reducer suitable for these reservoirs to effectively address the challenges of high oil washing and displacement difficulties. Summary of the Invention

[0009] Purpose of the invention: In view of the technical problem that existing viscosity reducers are generally applicable to medium-to-high permeability heavy oil reservoirs, but have low displacement intensity and weak oil washing ability in deep low permeability oil reservoirs, this invention discloses a viscosity reducer for the exploitation of deep low permeability heavy oil reservoirs, its preparation method and application, and solves the technical problem of low recovery rate in deep low permeability oil reservoirs.

[0010] Technical solution: A viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs, with the following structural formula:

[0011]

[0012] Wherein: M is Na, m is 3, 4 or 5, preferably m is 5.

[0013] The preparation method of the above-mentioned viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs includes the following steps:

[0014] (1) Under the presence of solvent and catalyst, under heating conditions, and under a nitrogen atmosphere or an inert gas atmosphere, 4-halogenated phthalic anhydride is reacted with glycol compounds in a nucleophilic addition reaction to obtain a mixture containing intermediate A.

[0015] (2) Diazomethane is passed into the mixture containing intermediate A, and the diazomethane reacts with intermediate A in a nuclear transfer reaction to obtain a mixture containing intermediate B;

[0016] (3) Add polyethylene glycol or dimethyl sulfite to the mixture containing intermediate B, stir evenly, and then add sodium sulfite. Under heating conditions, intermediate B and sodium sulfite undergo a sulfonation reaction of thermal displacement. After the reaction is completed, the viscosity reducer for deep low-permeability heavy oil reservoirs is obtained after post-treatment.

[0017] A viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs is prepared by any of the methods described above.

[0018] The above-mentioned viscosity reducers are used as displacement and flow-enhancing viscosity reducers in the exploitation of deep, low-permeability heavy oil reservoirs.

[0019] The viscosity reducer of this invention for deep, low-permeability heavy oil reservoir development is a water-soluble sulfonate-type anionic surfactant. This surfactant has two sulfonic acid groups and multiple ether bonds, exhibiting strong hydrophilicity, wherein:

[0020] The sulfonic acid group as a whole improves the temperature and salt resistance and strong oil washing ability of the viscosity reducer molecule. The benzene ring and carboxylic acid ester group on its molecule are lipophilic and attract each other with the asphaltene molecule, which leads to the destruction of the asphaltene network structure, reduces the viscosity of heavy oil, and ultimately achieves the performance of efficient oil washing and viscosity reduction.

[0021] Unlike traditional viscosity reducers, the viscosity reducer of this invention for deep, low-permeability heavy oil reservoirs has both oleophilic and hydrophilic properties, and is more effective in reducing viscosity and washing oil in deep, low-permeability heavy oil reservoirs.

[0022] Beneficial effects: The viscosity reducer for deep, low-permeability heavy oil reservoir development disclosed in this invention, its preparation method, and its uses have the following advantages:

[0023] (1) The raw materials are widely available, the synthesis process is simple, and the yield is high;

[0024] (2) It has multiple functions of viscosity reduction, oil displacement and oil washing. For extra-thick oil and super-thick oil, it can reduce the viscosity of thick oil to below 500 mPa·s and the static oil washing rate can reach more than 50%.

[0025] (3) It has excellent pressure and salt resistance, and can withstand pressure up to 80MPa and mineralization up to 50000mg / L.

[0026] (4) It has strong adaptability to oil reservoirs and can be widely used in the field of heavy oil viscosity reduction in deep, low-permeability oil reservoirs. Attached Figure Description

[0027] Figure 1 This is a flowchart of the preparation method of the viscosity reducer for deep, low-permeability heavy oil reservoirs disclosed in this invention. Detailed Implementation

[0028] The specific embodiments of the present invention are described in detail below.

[0029] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10–50 is listed for a specific parameter, it is also expected that ranges of 10–40 and 20–50 are also included. Furthermore, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0–5" means that all real numbers between "0–5" have been listed herein; "0–5" is merely a shortened representation of these numerical combinations.

[0030] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0031] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0032] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0033] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0034] Unless otherwise specified, the reaction will proceed under normal temperature and pressure conditions.

[0035] Unless otherwise specified, all parts or percentages are by weight or by weight percentage.

[0036] In this invention, all the substances used are known substances that can be purchased or synthesized by known methods.

[0037] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0038] Taking 4-bromophthalic anhydride as an example, the reaction equation for the synthetic route of this invention is as follows:

[0039] first step:

[0040]

[0041] Step Two:

[0042]

[0043] Step 3:

[0044]

[0045] The viscosity reducer used in the exploitation of deep, low-permeability heavy oil reservoirs has the following structural formula:

[0046]

[0047] Wherein: M is Na, m is 3, 4 or 5, preferably m is 5.

[0048] The preparation method of the above-mentioned viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs includes the following steps:

[0049] (1) Under the presence of solvent and catalyst, under heating conditions, and under a nitrogen atmosphere or an inert gas atmosphere, 4-halogenated phthalic anhydride is reacted with glycol compounds in a nucleophilic addition reaction to obtain a mixture containing intermediate A.

[0050] (2) Diazomethane is passed into the mixture containing intermediate A, and the diazomethane reacts with intermediate A in a nuclear transfer reaction to obtain a mixture containing intermediate B;

[0051] (3) Add polyethylene glycol or dimethyl sulfite to the mixture containing intermediate B, stir evenly, and then add sodium sulfite. Under heating conditions, intermediate B and sodium sulfite undergo a sulfonation reaction of thermal displacement. After the reaction is completed, the viscosity reducer for deep low-permeability heavy oil reservoirs is obtained after post-treatment.

[0052] Furthermore, the glycol compound described in step (1) has the structure shown in formula (1):

[0053] Where m is 3, 4, or 5.

[0054] Further, the 4-halophthalic anhydride mentioned in step (1) is one of 4-bromophthalic anhydride, 4-chlorophthalic anhydride, and 4-iodophthalic anhydride, and / or

[0055] The molar ratio of 4-halophthalic anhydride to glycol in step (1) is (2-2.4):1, preferably (2.1-2.3):1.

[0056] Further, the solvent mentioned in step (1) is one of water, xylene, and / or

[0057] The ratio of the amount of solvent used in step (1) to the mass of 4-halophthalic anhydride is (8-15):1.

[0058] Furthermore, the reaction temperature of the nucleophilic addition reaction in step (1) is controlled at at least 40°C, preferably 40-60°C, and the reaction time is controlled at at least 1 hour.

[0059] Further, the catalyst mentioned in step (1) is one of sodium acetate, phthalic acid, cobalt chloride, and / or

[0060] The mass ratio of the catalyst to 4-halophthalic anhydride in step (1) is (0.01-0.05):1.

[0061] Furthermore, the molar ratio of the diazomethane added in step (2) to the amount of glycol compound used in step (1) is (2-2.2):1, preferably (2.05-2.15):1.

[0062] Furthermore, the ratio of the amount of polyethylene glycol or dimethyl sulfoxide used in step (3) to the mass of 4-halophthalic anhydride in step (1) is (1.4-5):1.

[0063] Further, the molar ratio of the amount of glycol compound in step (1) to the amount of sodium sulfite added in step (3) is 1:(2-2.2), preferably 1:(2.05-2.15).

[0064] Furthermore, the specific post-processing steps described in step (3) are as follows:

[0065] Pour the reaction solution into a reaction vessel, add an appropriate amount of NaCl aqueous solution with a mass concentration of 10%-26.4%, heat to at least 80°C, preferably 80-85°C, allow to cool naturally to below 50°C, then cool to below 5°C, and continue stirring for at least 30 minutes, preferably 30-50 minutes. Extract with xylene, filter, and recrystallize the filter cake with water to obtain a pale yellow powdery solid.

[0066] Furthermore, the amount of NaCl aqueous solution used in step (3) is 0.45-0.8 times the amount of 4-halophthalic anhydride used in step (1), and / or

[0067] The amount of xylene used in step (3) is 5-10 times the amount of 4-halophthalic anhydride used in step (1).

[0068] In one specific implementation, a method for preparing a viscosity reducer for deep, low-permeability heavy oil reservoir development includes the following steps, by weight:

[0069] (A) Add 1 part of 4-halophthalic anhydride, an appropriate amount of glycol compound, and 8-15 parts of water to a reactor equipped with a thermometer and a stirrer. Heat while stirring at a rate of 300-400 rpm at a temperature of 40-50°C. Purge with nitrogen or an inert gas for at least 3 minutes. Then, add 0.01-0.05 parts of catalyst, increase the temperature to at least 60°C, adjust the stirring rate to 500-600 rpm, and continue the reaction for at least 1 hour. Then cool to room temperature to obtain a mixture containing intermediate A, wherein:

[0070] The molar ratio of glycol compounds to the 4-halophthalic anhydride is 1:(2-2.4);

[0071] (B) Diazomethane is introduced into the mixture containing intermediate A. The stirring rate is adjusted to 500-600 rpm, and the heating temperature is adjusted to at least 60°C. The color change of the gas in the reactor is observed. When the gas in the reactor turns light yellow and no longer changes color, and no bubbles are generated, the reactor is placed in a ventilated area and allowed to stand for at least 1 hour. Then, it is cooled to room temperature to obtain a mixture containing intermediate B, wherein:

[0072] The molar ratio of the diazomethane added in step (B) to the amount of glycol compound used in step (A) is (2-2.2):1;

[0073] (C) Add 1.4-5 parts of polyethylene glycol or dimethyl sulfoxide to the mixture containing intermediate B, adjust the stirring speed to 500-600 rpm, heat to 60°C, and stir for at least 30 min. Then add an appropriate amount of sodium sulfite to the reaction mixture, and continue stirring at 60-65°C for at least 1 hour to obtain a mixture. Then pour the above mixture into another reactor, add 0.45-0.8 parts of a 10%-26.4% NaCl aqueous solution, heat to at least 80°C, preferably 80-85°C, cool to below 5°C, and continue stirring for at least 30 min, preferably 30-50 min. Extract with xylene, filter, and recrystallize the filter cake with water to obtain a pale yellow powdery solid, wherein:

[0074] The molar ratio of the amount of glycol compound in step (A) to the amount of sodium sulfite added in step (C) is 1:(2-2.2).

[0075] Viscosity reducers used in the exploitation of deep, low-permeability heavy oil reservoirs are prepared by any of the methods described above.

[0076] The above-mentioned viscosity reducers are used as displacement and flow-enhancing viscosity reducers in the exploitation of deep, low-permeability heavy oil reservoirs.

[0077] Furthermore, the viscosity reducer is prepared as an aqueous solution with a concentration of 100-1500 mg / L, preferably 200-1200 mg / L, and more preferably 500-1000 mg / L, and directly injected into deep, low-permeability heavy oil reservoirs.

[0078] Unbound by any theory, the inventors discovered that the viscosity reducer of the present invention has excellent modification effects on the surfaces of oil, water and rock, and can have the functions of viscosity reduction, oil washing and dialysis displacement, which can meet the needs of deep low-permeability heavy oil reservoir development.

[0079] In one embodiment:

[0080] The viscosity reducer used in the exploitation of deep, low-permeability heavy oil reservoirs has the following structural formula:

[0081]

[0082] Where M is Na and m is 3.

[0083] The preparation method of the above-mentioned viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs includes the following steps:

[0084] (1) Under the presence of solvent and catalyst, under heating conditions and in a nitrogen atmosphere, 4-halogenated phthalic anhydride is reacted with glycol compounds in a nucleophilic addition reaction to obtain a mixture containing intermediate A.

[0085] (2) Diazomethane is passed into the mixture containing intermediate A, and the diazomethane reacts with intermediate A in a nuclear transfer reaction to obtain a mixture containing intermediate B;

[0086] (3) Add polyethylene glycol or dimethyl sulfite to the mixture containing intermediate B, stir evenly, and then add sodium sulfite. Under heating conditions, intermediate B and sodium sulfite undergo a sulfonation reaction of thermal displacement. After the reaction is completed, the viscosity reducer for deep low-permeability heavy oil reservoirs is obtained after post-treatment.

[0087] Furthermore, the glycol compound described in step (1) has the structure shown in formula (1):

[0088] Where m is 3.

[0089] Further, the 4-halophthalic anhydride mentioned in step (1) is 4-bromophthalic anhydride, and / or

[0090] In step (1), the molar ratio of the 4-halophthalic anhydride to the glycol compound is 2:1. In other embodiments, the molar ratio of the 4-halophthalic anhydride to the glycol compound in step (1) is 2.1:1.

[0091] Further, the solvent mentioned in step (1) is water, and / or

[0092] The ratio of the amount of solvent used in step (1) to the mass of 4-halophthalic anhydride is 8:1.

[0093] Furthermore, the reaction temperature of the nucleophilic addition reaction described in step (1) is controlled at 40°C, and the reaction time is controlled at 3 hours.

[0094] Further, the catalyst mentioned in step (1) is sodium acetate, and / or

[0095] The mass ratio of the catalyst to 4-halophthalic anhydride in step (1) is 0.01:1.

[0096] Furthermore, the molar ratio of the diazomethane added in step (2) to the amount of glycol compound used in step (1) is 2:1. In other embodiments, the molar ratio of the diazomethane added in step (2) to the amount of glycol compound used in step (1) is 2.05:1.

[0097] Furthermore, the ratio of the amount of polyethylene glycol or dimethyl sulfoxide used in step (3) to the mass of 4-halophthalic anhydride in step (1) is 1.4:1.

[0098] Further, the molar ratio of the amount of glycol compound in step (1) to the amount of sodium sulfite added in step (3) is 1:2. In other embodiments, the molar ratio of the amount of glycol compound in step (1) to the amount of sodium sulfite added in step (3) is 1:2.05.

[0099] Furthermore, the specific post-processing steps described in step (3) are as follows:

[0100] The reaction solution was poured into a reaction vessel, and an appropriate amount of 10% NaCl aqueous solution was added. The temperature was raised to 80°C, and then naturally cooled to 50°C. The mixture was then cooled to 5°C with an ice-water mixture, and stirred for 30 minutes. The mixture was extracted with xylene, filtered, and the filter cake was recrystallized with water to obtain a pale yellow powdery solid.

[0101] Furthermore, the amount of NaCl aqueous solution used in step (3) is 0.45 times the amount of 4-halophthalic anhydride used in step (1), and / or

[0102] The amount of xylene used in step (3) is 5 times the amount of 4-halophthalic anhydride used in step (1).

[0103] In one specific implementation, a method for preparing a viscosity reducer for deep, low-permeability heavy oil reservoir development includes the following steps, by weight:

[0104] (A) One part of 4-halophthalic anhydride, an appropriate amount of glycol compound, and eight parts of water were added to a reactor equipped with a thermometer and a stirrer. The mixture was heated while stirring at 300 rpm at a temperature of 40°C. Nitrogen or inert gas was introduced for 10 minutes. Then, 0.01 parts of catalyst were added, the temperature was increased to 60°C, the stirring rate was adjusted to 500 rpm, and the reaction continued for 3 hours. The mixture was then cooled to room temperature to obtain a mixture containing intermediate A, wherein:

[0105] The molar ratio of glycol compounds to the 4-halophthalic anhydride is 1:2;

[0106] (B) Diazomethane was introduced into the mixture containing intermediate A. The stirring rate was adjusted to 600 rpm, and the heating temperature was adjusted to 70°C. The color change of the gas in the reactor was observed. When the gas in the reactor turned light yellow and remained unchanged, and no bubbles were generated, the reactor was placed in a ventilated area and allowed to stand for 1 hour. Then, it was cooled to room temperature to obtain a mixture containing intermediate B, wherein:

[0107] The molar ratio of the diazomethane added in step (B) to the amount of glycol compound used in step (A) is 2:1;

[0108] (C) 1.4 parts of polyethylene glycol were added to the mixture containing intermediate B. The stirring speed was adjusted to 500 rpm, and the mixture was heated to 60°C and stirred for 30 min. Then, an appropriate amount of sodium sulfite was added to the reaction mixture. The mixture was stirred for another 3 hours at 60°C to obtain a final mixture. The final mixture was then poured into another reactor, and 0.45 parts of a 10% NaCl aqueous solution were added. The mixture was heated to 80°C, allowed to cool naturally to 50°C, and then cooled to 5°C with an ice-water mixture. The mixture was stirred for another 30 min, extracted with xylene, filtered, and the filter cake was recrystallized with water to obtain a pale yellow powdery solid, in which:

[0109] The molar ratio of the amount of glycol compound in step (A) to the amount of sodium sulfite added in step (C) is 1:2.

[0110] Viscosity reducers used in the exploitation of deep, low-permeability heavy oil reservoirs are prepared by any of the methods described above.

[0111] The aforementioned viscosity reducers used in the exploitation of deep, low-permeability heavy oil reservoirs are applied as displacement and flow-enhancing viscosity reducers in the exploitation of deep, low-permeability heavy oil reservoirs.

[0112] Furthermore, the viscosity reducer is prepared into an aqueous solution with a concentration of 100 mg / L and directly injected into deep, low-permeability heavy oil reservoirs.

[0113] In other embodiments, the viscosity reducer is prepared as an aqueous solution with a concentration of 200 mg / L and directly injected into deep, low-permeability heavy oil reservoirs.

[0114] In other embodiments, the viscosity reducer is prepared as an aqueous solution with a concentration of 500 mg / L and directly injected into deep, low-permeability heavy oil reservoirs.

[0115] In another embodiment:

[0116] The viscosity reducer used in the exploitation of deep, low-permeability heavy oil reservoirs has the following structural formula:

[0117]

[0118] Where M is Na and m is 4.

[0119] The preparation method of the above-mentioned viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs includes the following steps:

[0120] (1) Under the presence of solvent and catalyst, under heating conditions and under an argon atmosphere, 4-halogenated phthalic anhydride is reacted with glycol compounds in a nucleophilic addition reaction to obtain a mixture containing intermediate A.

[0121] (2) Diazomethane is passed into the mixture containing intermediate A, and the diazomethane reacts with intermediate A in a nuclear transfer reaction to obtain a mixture containing intermediate B;

[0122] (3) Add dimethyl sulfoxide to the mixture containing intermediate B, stir evenly, and then add sodium sulfite. Under heating conditions, intermediate B and sodium sulfite undergo a sulfonation reaction of thermal displacement. After the reaction is completed, a viscosity reducer for deep, low-permeability heavy oil reservoirs is obtained after post-treatment.

[0123] Furthermore, the glycol compound described in step (1) has the structure shown in formula (1):

[0124] Where m is 4.

[0125] Further, the 4-halophthalic anhydride mentioned in step (1) is 4-chlorophthalic anhydride, and / or

[0126] In step (1), the molar ratio of the 4-halophthalic anhydride to the glycol compound is 2.4:1. In other embodiments, the molar ratio of the 4-halophthalic anhydride to the glycol compound in step (1) is 2.3:1.

[0127] Further, the solvent mentioned in step (1) is xylene, and / or

[0128] The ratio of the amount of solvent used in step (1) to the mass of 4-halophthalic anhydride is 15:1.

[0129] Furthermore, the reaction temperature of the nucleophilic addition reaction described in step (1) is controlled at 60°C, and the reaction time is controlled at 1 hour.

[0130] Further, the catalyst described in step (1) is phthalic acid, and / or

[0131] The mass ratio of the catalyst to 4-halophthalic anhydride in step (1) is 0.05:1.

[0132] Further, the molar ratio of the diazomethane added in step (2) to the amount of glycol compound used in step (1) is 2.2:1. In other embodiments, the molar ratio of the diazomethane added in step (2) to the amount of glycol compound used in step (1) is 2.15:1.

[0133] Furthermore, the ratio of the amount of polyethylene glycol or dimethyl sulfoxide used in step (3) to the mass of 4-halophthalic anhydride in step (1) is 5:1.

[0134] Further, the molar ratio of the amount of glycol compound in step (1) to the amount of sodium sulfite added in step (3) is 1:2.2. In other embodiments, the molar ratio of the amount of glycol compound in step (1) to the amount of sodium sulfite added in step (3) is 1:2.15.

[0135] Furthermore, the specific post-processing steps described in step (3) are as follows:

[0136] The reaction solution was poured into a reaction vessel, and an appropriate amount of 26.4% NaCl aqueous solution was added. The temperature was raised to 85°C, and then naturally cooled to 48°C. The solution was then cooled to 3°C with an ice-water mixture, and the mixture was stirred for 50 minutes. The solution was extracted with xylene, filtered, and the filter cake was recrystallized with water to obtain a pale yellow powdery solid.

[0137] Furthermore, the amount of NaCl aqueous solution used in step (3) is 0.8 times the amount of 4-halophthalic anhydride used in step (1), and / or

[0138] The amount of xylene used in step (3) is 10 times the amount of 4-halophthalic anhydride used in step (1).

[0139] In one specific implementation, a method for preparing a viscosity reducer for deep, low-permeability heavy oil reservoir development includes the following steps, by weight:

[0140] (A) One part of 4-halophthalic anhydride, an appropriate amount of glycol compound, and 15 parts of water were added to a reactor equipped with a thermometer and a stirrer. The mixture was heated while stirring at 400 rpm at a temperature of 50°C. Argon gas was introduced for 3 minutes. Then, 0.05 parts of catalyst were added, the temperature was increased to 60°C, the stirring rate was adjusted to 600 rpm, and the reaction continued for 1 hour. The mixture was then cooled to room temperature to obtain a mixture containing intermediate A, wherein:

[0141] The molar ratio of glycol compounds to the 4-halophthalic anhydride is 1:2.4;

[0142] (B) Diazomethane was introduced into the mixture containing intermediate A. The stirring speed was adjusted to 600 rpm, and the heating temperature was adjusted to 60°C. The color change of the gas in the reactor was observed. When the gas in the reactor turned light yellow and no longer changed, and no bubbles were generated, the reactor was placed in a ventilated area and allowed to stand for 1 hour. Then, it was cooled to room temperature to obtain a mixture containing intermediate B, wherein:

[0143] The molar ratio of the diazomethane added in step (B) to the amount of glycol compound used in step (A) is 2.2:1;

[0144] (C) Add 5 parts of dimethyl sulfite to the mixture containing intermediate B, adjust the stirring speed to 600 rpm, heat to 60°C, and stir for 30 min. Then add an appropriate amount of sodium sulfite to the reaction mixture, and continue stirring at 65°C for 1 hour to obtain a mixture. Then pour the above mixture into another reactor, add 0.8 parts of a 26.4% NaCl aqueous solution, heat to 85°C, cool naturally to 50°C, then cool to 5°C with an ice-water mixture, continue stirring for 50 min, extract with xylene, filter, and recrystallize the filter cake with water to obtain a pale yellow powdery solid, in which:

[0145] The molar ratio of the amount of glycol compound in step (A) to the amount of sodium sulfite added in step (C) is 1:2.2.

[0146] A viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs is prepared by any of the methods described above.

[0147] The aforementioned viscosity reducers used in the exploitation of deep, low-permeability heavy oil reservoirs are applied as displacement and flow-enhancing viscosity reducers in the exploitation of deep, low-permeability heavy oil reservoirs.

[0148] Furthermore, the viscosity reducer is prepared into an aqueous solution with a concentration of 1500 mg / L and directly injected into deep, low-permeability heavy oil reservoirs.

[0149] In other embodiments, the viscosity reducer is prepared as an aqueous solution with a concentration of 1200 mg / L and directly injected into deep, low-permeability heavy oil reservoirs.

[0150] In other embodiments, the viscosity reducer is prepared as an aqueous solution with a concentration of 1000 mg / L and directly injected into deep, low-permeability heavy oil reservoirs.

[0151] In yet another embodiment:

[0152] The viscosity reducer used in the exploitation of deep, low-permeability heavy oil reservoirs has the following structural formula:

[0153]

[0154] Where M is Na and m is 5.

[0155] The preparation method of a viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs includes the following steps:

[0156] (1) Under the presence of solvent and catalyst, under heating conditions and in a helium atmosphere, 4-halogenated phthalic anhydride is reacted with glycol compounds in a nucleophilic addition reaction to obtain a mixture containing intermediate A.

[0157] (2) Diazomethane is passed into the mixture containing intermediate A, and the diazomethane reacts with intermediate A in a nuclear transfer reaction to obtain a mixture containing intermediate B;

[0158] (3) Polyethylene glycol is added to the mixture containing intermediate B, and after stirring evenly, sodium sulfite is added to it. Under heating conditions, intermediate B and sodium sulfite undergo a sulfonation reaction of thermal displacement. After the reaction is completed, a viscosity reducer for deep low-permeability heavy oil reservoirs is obtained after post-treatment.

[0159] Furthermore, the glycol compound described in step (1) has the structure shown in formula (1):

[0160] Where m is 5.

[0161] Further, the 4-halophthalic anhydride mentioned in step (1) is 4-chlorophthalic anhydride, and / or

[0162] The molar ratio of the 4-halophthalic anhydride to the glycol compound in step (1) is 2.2:1.

[0163] Further, the solvent mentioned in step (1) is water, and / or

[0164] The ratio of the amount of solvent used in step (1) to the mass of 4-halophthalic anhydride is 10:1.

[0165] Furthermore, the reaction temperature of the nucleophilic addition reaction described in step (1) is controlled at 50°C, and the reaction time is controlled at 2 hours.

[0166] Further, the catalyst in step (1) is cobalt chloride, and / or

[0167] The mass ratio of the catalyst to 4-halophthalic anhydride in step (1) is 0.02:1.

[0168] Furthermore, the molar ratio of the diazomethane added in step (2) to the amount of glycol compound used in step (1) is 2.1:1.

[0169] Furthermore, the ratio of the amount of polyethylene glycol or dimethyl sulfoxide used in step (3) to the mass of 4-halophthalic anhydride in step (1) is 2:1.

[0170] Furthermore, the molar ratio of the amount of glycol compound in step (1) to the amount of sodium sulfite added in step (3) is 1:2.1.

[0171] Furthermore, the specific post-processing steps described in step (3) are as follows:

[0172] The reaction solution was poured into a reaction vessel, and an appropriate amount of 20% NaCl aqueous solution was added. The temperature was raised to 82°C, and then naturally cooled to 49°C. The mixture was then cooled to 4°C with an ice-water mixture. The mixture was stirred for 40 minutes, extracted with xylene, filtered, and the filter cake was recrystallized with water to obtain a pale yellow powdery solid.

[0173] Furthermore, the amount of NaCl aqueous solution used in step (3) is 0.6 times the amount of 4-halophthalic anhydride used in step (1), and / or

[0174] The amount of xylene used in step (3) is 8 times the amount of 4-halophthalic anhydride used in step (1).

[0175] In one specific implementation, a method for preparing a viscosity reducer for deep, low-permeability heavy oil reservoir development includes the following steps, by weight:

[0176] (A) One part of 4-halophthalic anhydride, an appropriate amount of glycol compound, and 10 parts of water were added to a reactor equipped with a thermometer and a stirrer. The mixture was heated while stirring at 350 rpm at a temperature of 45°C. Helium gas was introduced for 4 minutes. Then, 0.02 parts of catalyst were added, the temperature was increased to 70°C, the stirring rate was adjusted to 550 rpm, and the reaction continued for 2 hours. The mixture was then cooled to room temperature to obtain a mixture containing intermediate A, wherein:

[0177] The molar ratio of glycol compounds to the 4-halophthalic anhydride is 1:2.2;

[0178] (B) Diazomethane was introduced into the mixture containing intermediate A. The stirring speed was adjusted to 550 rpm, and the heating temperature was adjusted to 60°C. The color change of the gas in the reactor was observed. When the gas in the reactor turned light yellow and remained unchanged, and no bubbles were generated, the reactor was placed in a ventilated area and allowed to stand for 2 hours. Then, it was cooled to room temperature to obtain a mixture containing intermediate B, wherein:

[0179] The molar ratio of the diazomethane added in step (B) to the amount of glycol compound used in step (A) is 2.1:1;

[0180] (C) Add 1.4-5 parts of polyethylene glycol or to the mixture containing intermediate B, adjust the stirring speed to 550 rpm, heat to 60°C, and stir for 40 min. Then add an appropriate amount of sodium sulfite to the reaction mixture, and continue stirring at 62°C for 2 hours to obtain a mixture. Then pour the above mixture into another reactor, add 0.5 parts of a 20% NaCl aqueous solution, heat to 82°C, cool naturally to 50°C, and then cool to 5°C with an ice-water mixture. Continue stirring for 40 min, extract with xylene, filter, and recrystallize the filter cake with water to obtain a pale yellow powdery solid, wherein:

[0181] The molar ratio of the amount of glycol compound in step (A) to the amount of sodium sulfite added in step (C) is 1:2.1.

[0182] A viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs is prepared by any of the methods described above.

[0183] The above-mentioned viscosity reducers are used as displacement and flow-enhancing viscosity reducers in the exploitation of deep, low-permeability heavy oil reservoirs.

[0184] Furthermore, the viscosity reducer is prepared into an aqueous solution with a concentration of 800 mg / L and directly injected into deep, low-permeability heavy oil reservoirs.

[0185] The present invention will now be described in further detail with reference to embodiments.

[0186] Example 1

[0187] The preparation method of a viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs includes the following steps:

[0188] (1) 227g (1mol) of 4-bromophthalic anhydride, 0.47mol of triethylene glycol and 2270g of solvent water were added to a three-necked flask equipped with a thermometer and a stirrer. The mixture was heated while stirring at a stirring speed of 300rpm and a heating temperature of 40℃. Nitrogen gas was introduced for 3min. Then, 2.5g of sodium acetate was added as a catalyst, the heating temperature was increased to 60℃, the stirring speed was adjusted to 500rpm, and the reaction was continued for 1 hour. The mixture was then cooled to room temperature to obtain intermediate A mixture.

[0189] (2) Pass 0.97 mol of diazonium methane into the intermediate A mixture, adjust the stirring speed to 520 rpm, adjust the heating temperature to 60℃, observe the color change of the gas in the flask, and when the gas changes from light yellow to no longer change and no bubbles are produced, place it in a ventilated place and wait for 1 hour, then cool it to room temperature to obtain a mixture containing intermediate B.

[0190] (3) Add 0.97 mol of polyethylene glycol to the mixture containing intermediate B, adjust the stirring speed to 500 rpm, heat to 60°C, stir for 30 min, then add 0.81 mol (102 g) of sodium sulfite to the reaction mixture, continue stirring at 60°C for 1 hour to obtain the final product mixture, then pour the above final product mixture into a beaker, add 102 g of 26.4% NaCl aqueous solution, heat to 80°C, cool naturally to 50°C, then cool to 5°C with an ice-water mixture, continue stirring for 30 min, extract with xylene, filter, recrystallize the filter cake with water to obtain a light yellow powdery solid.

[0191] The pale yellow powdery solid was weighed, and the mass was 316g. The yield was calculated to be 93.2%.

[0192] Based on the required final concentration, the pale yellow powder solid prepared in this embodiment was mixed evenly with an appropriate amount of water to obtain an aqueous solution with a concentration of 500 mg / L, which was named viscosity reducer M1 for deep, low-permeability heavy oil reservoir development.

[0193] Example 2 – The preparation method is similar to that of Example 1, but 4-chlorophthalic anhydride is used instead of 4-bromophthalic anhydride, and tetraethylene glycol is used instead of triethylene glycol.

[0194] The preparation method of a viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs includes the following steps:

[0195] (1) 182.5 g (1 mol) of 4-chlorophthalic anhydride, 0.47 mol of tetraethylene glycol and 1460 g of solvent water were added to a three-necked flask equipped with a thermometer and a stirrer. The mixture was heated while stirring at a stirring rate of 320 rpm and a heating temperature of 40 °C. Argon gas was introduced for 4 min. Then, 1.825 g of sodium acetate was added as a catalyst, the heating temperature was increased to 60 °C, the stirring rate was adjusted to 520 rpm, and the reaction was continued for 90 min. The mixture was then cooled to room temperature to obtain a mixture containing intermediate A.

[0196] (2) Pass 0.97 mol of diazonium methane into the mixture containing intermediate A, adjust the stirring speed to 540 rpm, adjust the heating temperature to 60 ℃, observe the color change of the gas in the flask, and when the gas changes from light yellow and no more bubbles are produced, place it in a ventilated place and wait for 1 hour, then cool it to room temperature to obtain the mixture containing intermediate B.

[0197] (3) Add 0.97 mol of polyethylene glycol to the mixture containing intermediate B, adjust the stirring speed to 520 rpm, heat to 60°C, stir for 30 min, then add 118.44 g (0.94 mol) of sodium sulfite to the reaction mixture, and continue stirring for 1 hour at 60°C to obtain the final product mixture.

[0198] (4) Pour the above final product mixture into a beaker, add 145g of 10% NaCl aqueous solution, heat to 80°C, cool naturally to 50°C, then cool to 5°C with ice water, continue stirring for 40min, extract with xylene, filter, recrystallize the filter cake with water to obtain a light yellow powder solid.

[0199] The pale yellow powdery solid was weighed, and the mass was 329g. The yield was calculated to be 91.4%.

[0200] Based on the required final concentration, the pale yellow powder solid prepared in this embodiment was mixed evenly with an appropriate amount of water to obtain an aqueous solution with a concentration of 500 mg / L, which was named viscosity reducer M2 for deep, low-permeability heavy oil reservoir development.

[0201] Example 3 – The preparation method is similar to that of Example 1, but pentaethylene glycol is used instead of triethylene glycol.

[0202] The preparation method of a viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs includes the following steps:

[0203] (1) 227 g (1 mol) of 4-bromophthalic anhydride, 0.47 mol of pentaethylene glycol and 3405 g of xylene solvent were added to a three-necked flask equipped with a thermometer and a stirrer. The mixture was heated while stirring at a stirring rate of 360 rpm and a heating temperature of 50 °C. Helium gas was introduced for 5 min. Then, 11.35 g of sodium acetate was added as a catalyst, the heating temperature was increased to 60 °C, the stirring rate was adjusted to 560 rpm, and the reaction was continued for 4 hours. The mixture was then cooled to room temperature to obtain a mixture containing intermediate A.

[0204] (2) Pass 0.97 mol of diazonium methane into the mixture containing intermediate A, adjust the stirring speed to 580 rpm, adjust the heating temperature to 60 ℃, observe the color change of the gas in the flask, and when the gas changes from light yellow and no more bubbles are produced, place it in a ventilated place and wait for 1 hour, then cool it to room temperature to obtain the mixture containing intermediate B.

[0205] (3) Add 0.97 mol of polyethylene glycol to the mixture containing intermediate B, adjust the stirring speed to 560 rpm, heat to 60°C, stir for 30 min, then add 142 g of sodium sulfite to the reaction mixture, continue stirring for 2 hours at 65°C to obtain the final product mixture, then pour the above final product mixture into a beaker, add 126 g of 20% NaCl aqueous solution, heat to 85°C, cool naturally to 50°C, then cool to 5°C with ice water, continue stirring for 50 min, extract with xylene, filter, recrystallize the filter cake with water to obtain a light yellow powder solid.

[0206] The pale yellow powdery solid was weighed, and the mass was 344g. The yield was calculated to be 90.1%.

[0207] Based on the required final concentration, the pale yellow powder solid prepared in this embodiment was mixed evenly with an appropriate amount of water to obtain an aqueous solution with a concentration of 500 mg / L, which was named viscosity reducer M3 for deep, low-permeability heavy oil reservoir development.

[0208] Performance testing

[0209] 1. Evaluation experiment of indoor viscosity reduction rate

[0210] This experiment focuses on heavy oil M in a certain block of Shengli Oilfield. The reservoir has a burial depth of 2769.5m, a permeability of 256mD, a porosity of 0.23, a reservoir temperature of 94.1℃, a crude oil viscosity of 25300mPa.s, and is classified as extra-heavy oil. The emulsion water cut is 27.3%, the injected water salinity is 27210mg / L, and the calcium and magnesium ion concentration is 680mg / L.

[0211] The viscosity-reducing agents M1-M3 obtained in Examples 1-3 of this invention for the exploitation of deep, low-permeability heavy oil reservoirs, and commercially available water-soluble viscosity-reducing agent products M and N (purchased from Shandong Shengli Chemical Co., Ltd.) were used to evaluate the viscosity-reducing and oil-washing effects of the heavy oil.

[0212] The methods for determining the viscosity reduction rate and oil washing effect of viscosity reducers refer to Q / SH10201519-2016 "General Technical Conditions for Viscosity Reducers for Heavy Oil".

[0213] Static washing performance evaluation method: Based on oil sample M, oil sand was prepared at an oil-to-sand ratio of 1:4.35, subjected to high-pressure treatment at 70 MPa, and aged for 7 days. Other operating procedures were carried out according to method 5.8 in Q / SLCG 5370-1999. The experimental results are shown in Table 1.

[0214] Table 1. Test results of viscosity reduction rate and oil washing effect

[0215]

[0216] Test results show that the viscosity-reducing agents M1-M3 of this invention for the exploitation of deep, low-permeability heavy oil reservoirs have better viscosity-reducing effects and static oil washing rates than commercially available water-soluble viscosity-reducing agents M and N. The products of this invention achieve a viscosity-reducing rate of over 98% at a concentration of 500 mg / L and a temperature of 50°C, with post-reduction viscosities all below 500 mPa·s, and the dispersed emulsion particles are uniformly dispersed. The oil washing rate reaches over 40%, with M3 achieving a static oil washing rate of over 50%. Based on these results, the viscosity-reducing and oil-displacing agents of this invention fully meet the exploitation requirements of deep, low-permeability heavy oil reservoirs.

[0217] Table 1 also shows that the structure of viscosity reducers M1-M3 used in the exploitation of deep, low-permeability heavy oil reservoirs affects their viscosity-reducing and oil-washing effects. Among them, viscosity reducer M3, which contains more ether bonds, exhibits better viscosity-reducing and oil-washing effects than viscosity reducers and oil displacement agents M1 and M2.

[0218] 2. Pressure and salt resistance evaluation test

[0219] This experiment used heavy oil M, with a simulated reservoir temperature of 94.1℃. Nitrogen gas was introduced into viscosity reducer M3 (obtained in Example 3 for deep, low-permeability heavy oil reservoir development) to create a high-pressure environment. The mixture was aged under high pressure for 7 days. The viscosity reduction rate and wash-off rate were tested using a laboratory-prepared salinity-enhancing aqueous solution at a viscosity reducer concentration of 500 mg / L. The results are shown in Table 2.

[0220] Table 2 Test results under high pressure and high mineralization environment

[0221]

[0222] As can be seen from Table 2, increasing pressure and salinity has little effect on the viscosity-reducing and oil-washing effects of viscosity reducer M3 obtained in Example 3 for the exploitation of deep, low-permeability heavy oil reservoirs.

[0223] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs, characterized in that, Its structural formula is as follows: Wherein: M is Na, m is 3, 4 or 5, preferably m is 5.

2. The method for preparing the viscosity reducer for deep, low-permeability heavy oil reservoirs according to claim 1, characterized in that, Includes the following steps: (1) Under the presence of solvent and catalyst, under heating conditions, and under a nitrogen atmosphere or an inert gas atmosphere, 4-halogenated phthalic anhydride is reacted with glycol compounds in a nucleophilic addition reaction to obtain a mixture containing intermediate A. (2) Diazomethane is passed into the mixture containing intermediate A, and the diazomethane reacts with intermediate A in a nuclear transfer reaction to obtain a mixture containing intermediate B; (3) Add polyethylene glycol or dimethyl sulfite to the mixture containing intermediate B, stir evenly, and then add sodium sulfite. Under heating conditions, intermediate B and sodium sulfite undergo a sulfonation reaction of thermal displacement. After the reaction is completed, the viscosity reducer for deep low-permeability heavy oil reservoirs is obtained after post-treatment.

3. The method for preparing the viscosity reducer for deep, low-permeability heavy oil reservoirs as described in claim 2, characterized in that, The glycol compound in step (1) has the structure shown in formula (1): Where m is 3, 4, or 5.

4. The method for preparing the viscosity reducer for deep, low-permeability heavy oil reservoirs as described in claim 2, characterized in that, The 4-halophthalic anhydride mentioned in step (1) is one of 4-bromophthalic anhydride, 4-chlorophthalic anhydride, and 4-iodophthalic anhydride, and / or The molar ratio of 4-halophthalic anhydride to glycol in step (1) is (2-2.4):1, preferably (2.1-2.3):

1.

5. The method for preparing the viscosity reducer for deep, low-permeability heavy oil reservoirs as described in claim 2, characterized in that, The solvent mentioned in step (1) is one of water, xylene, and / or The ratio of the amount of solvent used in step (1) to the mass of 4-halophthalic anhydride is (8-15):

1.

6. The method for preparing the viscosity reducer for deep, low-permeability heavy oil reservoirs as described in claim 2, characterized in that, The reaction temperature of the nucleophilic addition reaction in step (1) is controlled at at least 40°C, preferably 40-60°C, and the reaction time is controlled at at least 1 hour.

7. The method for preparing the viscosity reducer for deep, low-permeability heavy oil reservoirs as described in claim 2, characterized in that, The catalyst mentioned in step (1) is one of sodium acetate, phthalic acid, cobalt chloride, and / or The mass ratio of the catalyst to 4-halophthalic anhydride in step (1) is (0.01-0.05):

1.

8. The method for preparing the viscosity reducer for deep, low-permeability heavy oil reservoirs as described in claim 2, characterized in that, The molar ratio of the diazomethane added in step (2) to the glycol compound used in step (1) is (2-2.2):1, preferably (2.05-2.15):1, and / or The ratio of the amount of polyethylene glycol or dimethyl sulfoxide used in step (3) to the mass of 4-halophthalic anhydride in step (1) is (1.4-5):1, and / or The molar ratio of the amount of glycol compound in step (1) to the amount of sodium sulfite added in step (3) is 1:(2-2.2), preferably 1:(2.05-2.15).

9. The method for preparing the viscosity reducer for deep, low-permeability heavy oil reservoirs as described in claim 2, characterized in that, The specific post-processing steps described in step (3) are as follows: Pour the reaction solution into a reaction vessel, add an appropriate amount of NaCl aqueous solution with a mass concentration of 10%-26.4%, heat to at least 80°C, preferably 80-85°C, allow to cool naturally to below 50°C, then cool to below 5°C, and continue stirring for at least 30 minutes, preferably 30-50 minutes. Extract with xylene, filter, and recrystallize the filter cake with water to obtain a pale yellow powdery solid.

10. The method for preparing the viscosity reducer for deep, low-permeability heavy oil reservoirs as described in claim 9, characterized in that, In step (3), the amount of NaCl aqueous solution used is 0.45-0.8 times the amount of 4-halophthalic anhydride used in step (1), and / or The amount of xylene used in step (3) is 5-10 times the amount of 4-halophthalic anhydride used in step (1).

11. The method for preparing the viscosity reducer for deep, low-permeability heavy oil reservoirs as described in claim 2, characterized in that, By weight, it includes the following steps: (A) Add 1 part of 4-halophthalic anhydride, an appropriate amount of glycol compound, and 8-15 parts of water to a reactor equipped with a thermometer and a stirrer. Heat while stirring at a rate of 300-400 rpm at a temperature of 40-50°C. Purge with nitrogen or an inert gas for at least 3 minutes. Then, add 0.01-0.05 parts of catalyst, increase the temperature to at least 60°C, adjust the stirring rate to 500-600 rpm, and continue the reaction for at least 1 hour. Then cool to room temperature to obtain a mixture containing intermediate A, wherein: The molar ratio of glycol compounds to the 4-halophthalic anhydride is 1:(2-2.4); (B) Diazomethane is introduced into the mixture containing intermediate A. The stirring rate is adjusted to 500-600 rpm, and the heating temperature is adjusted to at least 60°C. The color change of the gas in the reactor is observed. When the gas in the reactor turns light yellow and no longer changes color, and no bubbles are generated, the reactor is placed in a ventilated area and allowed to stand for at least 1 hour. Then, it is cooled to room temperature to obtain a mixture containing intermediate B, wherein: The molar ratio of the diazomethane added in step (B) to the amount of glycol compound used in step (A) is (2-2.2):1; (C) Add 1.4-5 parts of polyethylene glycol or dimethyl sulfoxide to the mixture containing intermediate B, adjust the stirring speed to 500-600 rpm, heat to 60°C, and stir for at least 30 min. Then add an appropriate amount of sodium sulfite to the reaction mixture, and continue stirring at 60-65°C for at least 1 hour to obtain a mixture. Then pour the above mixture into another reactor, add 0.45-0.8 parts of a 10%-26.4% NaCl aqueous solution, heat to at least 80°C, preferably 80-85°C, cool to below 5°C, and continue stirring for at least 30 min, preferably 30-50 min. Extract with xylene, filter, and recrystallize the filter cake with water to obtain a pale yellow powdery solid, wherein: The molar ratio of the amount of glycol compound in step (A) to the amount of sodium sulfite added in step (C) is 1:(2-2.2).

12. A viscosity reducer for the exploitation of deep, low-permeability heavy oil reservoirs, prepared by the method described in any one of claims 2-11.

13. The application of the viscosity reducer according to claim 1 or 12 as a displacement flow-enhancing viscosity reducer in the exploitation of deep, low-permeability heavy oil reservoirs.

14. The application as described in claim 13, characterized in that, The viscosity reducer is prepared as an aqueous solution with a concentration of 100-1500 mg / L, preferably 200-1200 mg / L, and more preferably 500-1000 mg / L, and is directly injected into deep, low-permeability heavy oil reservoirs.

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