An acid liquid reverse phase emulsion thickening agent for ultra-high temperature gelled acid and a preparation method thereof

Abstract

The present application relates to the technical field of oilfield chemicals, and discloses an acid liquid reverse emulsion thickening agent for super-high-temperature gelling acid and a preparation method thereof.The thickening agent is prepared by reverse emulsion polymerization of methacryloyloxyethyl trimethyl ammonium chloride monomers.The reverse emulsion comprises an aqueous phase and an oil phase.The raw materials of the aqueous phase include methacryloyloxyethyl trimethyl ammonium chloride monomers, an initiator, an auxiliary agent, secondary water and an aqueous phase emulsifier.The aqueous phase emulsifier is a combination of dodecyl trimethyl ammonium bromide and lauryl alcohol polyether.The raw materials of the oil phase include an oily medium and an oil phase emulsifier.The present application can solve the problems of the prior art, such as the difficulty in synthesizing pure homopolymer reverse emulsion of methacryloyloxyethyl trimethyl ammonium chloride (DMC), the insufficient thickening effect of the thickening agent in a super-high-temperature environment, and poor temperature resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield chemicals, in particular to an acid liquid reverse emulsion thickening agent for super-high-temperature gelled acid and a preparation method thereof. BACKGROUND

[0002] In the process of oil and gas exploitation, especially in acidizing treatment operation, acid liquid is usually used to dissolve carbonate minerals in rocks to improve the permeability of the reservoir. In order to improve the viscosity of the acid liquid and slow down the penetration speed of the acid liquid in the rock formation, a thickening agent is usually needed to be added. However, the existing acid liquid thickening agents have problems such as poor solubility and poor temperature adaptability, which affects the effectiveness of the acid liquid and the operation effect. In recent years, in order to solve the problem of insufficient high-temperature resistance of polymers in hydrochloric acid environment, increasing the cationic degree of the polymer itself has become an effective solution. As a commonly used cationic monomer, the higher the cationic degree of DMC is, the stronger the temperature resistance of the polymer is. In theory, using DMC homopolymerization can obtain a cationic homopolymer with super-high-temperature resistance. However, in the industry, there is only a case of preparing a dry powder from a water solution polymer, and there is no case of obtaining a uniform emulsion by reverse emulsion polymerization. The advantages of reverse emulsion polymerization over dry powder preparation are as follows: first, the product can be used directly without subsequent treatment; second, the solubility and dispersion of the product are greatly reduced compared with dry powder, and the prepared acid liquid is more uniform and stable in properties. However, the main difficulties in reverse emulsion polymerization are as follows: first, the strong hydrophilicity and high charge density characteristics of DMC monomer itself are in conflict with the physical and chemical requirements of the reverse emulsion system; second, the traditional Span / Tween non-ionic emulsifier (HLB 4-6) relies on the space steric stabilization mechanism, but the hydrophilic segment (polyoxyethylene) and the cationic group have charge repulsion, which reduces the adsorption efficiency of the emulsifier at the oil-water interface. Stable W / O emulsion requires low HLB (4-6), but the strong hydrophilicity of DMC requires high HLB (>10) to reduce the interfacial tension. The two cannot be compatible, and the conventional emulsifier compound fails to effectively synthesize the required product, which is a technical bottleneck. SUMMARY

[0003] The present application aims to provide an acid liquid reverse emulsion thickening agent for super-high-temperature gelled acid, to solve the problems of difficult synthesis of pure homopolymerization of methacryloyloxyethyl trimethyl ammonium chloride (DMC) reverse emulsion, insufficient thickening effect of the thickening agent in super-high-temperature environment, and poor temperature resistance.

[0004] Another object of the present application is to provide a preparation method of the acid liquid reverse emulsion thickening agent for super-high-temperature gelled acid.

[0005] The technical solution of the present application is as follows:

[0006] In one aspect, the present application provides an acid liquid inverse emulsion thickening agent for ultra-high temperature gelled acid, which is prepared from methacryloyloxyethyl trimethyl ammonium chloride monomer through inverse emulsion polymerization, and the inverse emulsion comprises an aqueous phase and an oil phase;

[0007] The aqueous phase raw materials include 350-450 parts of methacryloyloxyethyl trimethyl ammonium chloride monomer, 4-9 parts of initiator, 1-2 parts of auxiliary agent, 220-260 parts of secondary water and aqueous phase emulsifier by mass fraction; the aqueous phase emulsifier is a combination of 1-5 parts of dodecyl trimethyl ammonium bromide and 1-5 parts of lauryl alcohol polyether;

[0008] The oil phase raw materials include 220-260 parts of oily medium and 25-50 parts of oil phase emulsifier.

[0009] Further, the purity of the methacryloyloxyethyl trimethyl ammonium chloride monomer is 78-80%.

[0010] Further, the initiator includes a combination of 3-5 parts of oxidizing initiator and 1-4 parts of azo initiator by mass fraction, the oxidizing initiator includes one or more of potassium persulfate, ammonium persulfate and sodium persulfate, and the azo initiator includes one or more of 2,2'-azobis(2-imidazoline) dihydrochloride, azobis isobutyronitrile and azobis isobutyl amidine.

[0011] Further, the auxiliary agent is disodium EDTA.

[0012] Further, the oily medium includes one or more of 3# white oil, 10# white oil and 15# white oil.

[0013] Further, the oil phase emulsifier includes a combination of 20-35 parts of Span 80 and 5-15 parts of Tween emulsifier by mass fraction, and the Tween emulsifier includes one or more of Tween 80, Tween 81 and Tween 60.

[0014] Further, characterized in that the inverse emulsion polymerization is initiated by adding an aqueous solution of a reducing initiator, and the reducing initiator includes one or more of ammonium sulfite, sodium sulfite, sodium metabisulfite and potassium metabisulfite.

[0015] In another aspect, the present application provides a preparation method of an acid liquid inverse emulsion thickening agent for ultra-high temperature gelled acid, which comprises the following steps:

[0016] S1. Mix and stir the aqueous phase components to be uniform, and perform deoxygenation treatment to obtain an aqueous phase;

[0017] S2. Stir the oil phase components until the oil phase is clear and uniform to obtain an oil phase;

[0018] S3. The water phase is added to the oil phase, and emulsified to a viscosity of 2200-2500 cp of the reaction system, to obtain a uniform emulsion;

[0019] S4. The uniform emulsion is subjected to oxygen removal treatment, and a water solution of a reducing initiator with a concentration of 1-5% is added to initiate the polymerization reaction, to obtain an acid liquid reverse phase emulsion thickener for super-high temperature gelling acid.

[0020] Further, in step S1, ultrasonic waves are used in combination with mechanical stirring, at a speed of 300 rpm; the oxygen removal treatment is performed by passing nitrogen, for 2-3 h.

[0021] Further, in step S4, the oxygen removal treatment is performed by passing nitrogen for 20-30 min, while stirring at a speed of 150-250 rpm; the water solution of the reducing initiator is injected by a micro-injection pump, at a speed of 5-10 mL / h, and the reaction temperature is controlled at 35-60℃, and the reaction time is 3-5 h.

[0022] Compared with the prior art, the embodiments of the present application have at least the following advantages or beneficial effects:

[0023] 1. By the synergistic effect of dodecyltrimethylammonium bromide and lauryl polyether, the essential conflict between the strong hydrophilicity of DMC and the physical and chemical requirements of the reverse phase emulsion system is made up, the phenomena of droplet coalescence and premature gelation are effectively inhibited, the stable synthesis of the pure homopolymer reverse phase emulsion of DMC is realized, and the technical bottleneck of poor emulsion stability in the traditional process is overcome.

[0024] 2. In 20% HCl acid liquid, the viscosity of the thickener is significantly improved with the increase of the amount, and is much better than that of the product without the specific water phase emulsifier and the existing product, and can flexibly meet the viscosity requirements of different acidizing operations.

[0025] 3. Under the super-high temperature environment of 140-200℃, the thickener can still maintain stable viscosity and uniform state without stratification and caking; while the existing product has serious stratification and caking under the same conditions, which proves that the product of the present application can adapt to extreme high temperature working conditions such as deep wells and ultra-deep wells.

[0026] 4. Compared with the problem of difficult liquid preparation of traditional dry powder thickener, the reverse phase emulsion thickener of the present application can be directly mixed with acid liquid, has good dispersibility and high liquid preparation efficiency, and can effectively improve the construction efficiency of oil and gas field acidizing operations. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. Other related drawings can also be obtained by those of ordinary skill in the art without creative labor on the basis of these drawings.

[0028] Figure 1 Product chart of acid liquid prepared for the product of example 1 of the present application;

[0029] Figure 2 Product state chart of example 1 of the present application after temperature resistance test;

[0030] Figure 3 Product state chart of comparative example 4 of the present application after temperature resistance test;

[0031] Figure 4 Product chart prepared by example 1 of the present application;

[0032] Figure 5 Infrared spectrum chart of the product of example 1 of the present application;

[0033] Figure 6 Deuterium water phase 1H-NMR chart of the product of example 1 of the present application;

[0034] Figure 7 Optical microscopic schematic diagram after premature gelation;

[0035] Figure 8 Schematic diagram of emulsion state under 50 times optical microscope. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely as follows. The specific conditions not mentioned in the embodiments are carried out according to conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased in the market.

[0037] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail with reference to specific embodiments.

[0038] The present application proposes a preparation method of acid liquid reverse phase emulsion thickening agent for ultra-high temperature gelling acid, which is prepared from methacryloxyethyl trimethyl ammonium chloride monomer (DMC) through reverse phase emulsion polymerization reaction. The reverse phase emulsion includes water phase and oil phase, and the preparation method includes the following steps:

[0039] S1. The water phase components are mixed and stirred uniformly using ultrasonic waves in combination with mechanical stirring at a speed of 300 rpm, and deoxygenated by passing nitrogen gas for 2-3 h to obtain a water phase; the water phase components include, by mass fraction, 350-450 parts of methylacryloyloxyethyl trimethyl ammonium chloride monomer with a purity of 78-80%, 4-9 parts of an initiator, 1-2 parts of an auxiliary agent, 220-260 parts of secondary water, and a water phase emulsifier; the water phase emulsifier is a combination of 1-5 parts of dodecyl trimethyl ammonium bromide and 1-5 parts of lauryl alcohol polyether, the initiator includes a combination of 3-5 parts of an oxidation initiator and 1-4 parts of an azo initiator, the oxidation initiator includes one or more of potassium persulfate, ammonium persulfate, and sodium persulfate, the azo initiator includes one or more of 2,2'-azobis(2-imidazoline) dihydrochloride, azobisisobutyronitrile, and azobis isobutyl amidine, and the auxiliary agent is disodium EDTA;

[0040] S2. The oil phase components are mechanically stirred at a speed of 300 rpm until the oil phase is clear and uniform to obtain an oil phase; the oil phase components include, by mass fraction, 220-260 parts of an oily medium and 25-50 parts of an oil phase emulsifier, the oily medium includes one or more of 3# white oil, 10# white oil, and 15# white oil, and the oil phase emulsifier includes a combination of 20-35 parts of Span 80 and 5-15 parts of a Tween emulsifier, and the Tween emulsifier includes one or more of Tween 80, Tween 81, and Tween 60;

[0041] S3. The water phase is added to the oil phase, and emulsification is performed using a high-speed homogenizer until the viscosity of the reaction system is 2200-2500 cp to obtain a uniform emulsion;

[0042] S4. The uniform emulsion is deoxygenated by passing nitrogen gas for 20-30 min while stirring at a speed of 150-250 rpm, a 1-5% aqueous solution of a reducing initiator is added to initiate the polymerization reaction to obtain an acid liquid reverse-phase emulsion thickening agent for super-high-temperature gelling acid, the aqueous solution of the reducing initiator is injected through a micro-injection pump at a speed of 5-10 mL / h, the reaction temperature is controlled at 35-60°C, and the reaction time is 3-5 h.

[0043] The features and performance of the present application are further described in detail below in conjunction with examples.

[0044] Example 1

[0045] The present example provides a preparation method of an acid liquid reverse-phase emulsion thickening agent for super-high-temperature gelling acid, including the following steps:

[0046] S1. Using ultrasonic with mechanical stirring, 420 parts of DMC, 230 parts of secondary water, 1 part of potassium persulfate, 1 part of sodium persulfate, 1 part of 2,2'-azobis(2-imidazoline) dihydrochloride, 2 parts of dodecyltrimethylammonium bromide, 2 parts of lauryl alcohol polyether, 1 part of EDTA 2Na, were dissolved uniformly, and nitrogen was introduced to remove oxygen for 2h to obtain an aqueous phase;

[0047] S2. Using mechanical stirring, 90 parts of 3# white oil, 30 parts of 10# white oil, 110 parts of 15# white oil were added to the reaction bottle, and then 28 parts of Span 80, 3 parts of Tween 81, 1 part of Tween 80 were added and stirred until the oil phase was clear and uniform to obtain an oil phase;

[0048] S3. Pour the aqueous phase into the oil phase, use a high-speed homogenizer, control the speed to 20,000 rpm, emulsify for 15 minutes, finally emulsify the viscosity of the reaction system to 2330 cp, and obtain a uniform emulsion;

[0049] S4. Connect the uniform emulsion to the reactor, introduce nitrogen below the emulsion surface, continue to remove oxygen for 30 minutes, use a mechanical stirrer to continue stirring, control the speed at 250 rpm, prepare a 5% solution of sodium sulfite and ammonium sulfite in a ratio of 2:1, use a micro-injection pump to inject into the reaction system at a speed of 1 mL / h, control the reaction temperature at 35℃, and continue to react for 5h to obtain the product.

[0050] Example 2

[0051] The present embodiment provides a preparation method of an acid liquid reverse-phase emulsion thickening agent for ultra-high temperature gelling acid, comprising the following steps:

[0052] S1. Using ultrasonic with mechanical stirring, 420 parts of DMC, 230 parts of secondary water, 1 part of potassium persulfate, 1 part of sodium persulfate, 1 part of 2,2'-azobis(2-imidazoline) dihydrochloride, 2 parts of dodecyltrimethylammonium bromide, 2 parts of lauryl alcohol polyether, 1 part of EDTA 2Na, were dissolved uniformly, and nitrogen was introduced to remove oxygen for 2h to obtain an aqueous phase;

[0053] S2. Using mechanical stirring, 90 parts of 3# white oil, 30 parts of 10# white oil, 110 parts of 15# white oil were added to the reaction bottle, and then 28 parts of Span 80, 3 parts of Tween 81, 1 part of Tween 80 were added and stirred until the oil phase was clear and uniform to obtain an oil phase;

[0054] S3. Pour the aqueous phase into the oil phase, use a high-speed homogenizer, control the speed to 20,000 rpm, emulsify for 15 minutes, finally emulsify the viscosity of the reaction system to 2330 cp, and obtain a uniform emulsion;

[0055] S4. The uniform emulsion is connected to the reactor, nitrogen is introduced to below the emulsion surface, oxygen removal is continued for 30 minutes, mechanical stirrer is used for continuous stirring during the period, the rotating speed is controlled at 250 rpm, sodium sulfite, ammonium sulfite are prepared into 2% solution in the proportion of 1:1, micro-injection pump is used to inject into the reaction system at the speed of 4 mL / h, the reaction temperature is controlled at 45°C, the reaction is continued for 3.5 h to obtain the product.

[0056] Example 3

[0057] The embodiment provides a preparation method of an acid liquid reverse-phase emulsion thickening agent for ultra-high temperature gelling acid, comprising the following steps:

[0058] S1. Using ultrasonic and mechanical stirring, 400 parts of DMC, 260 parts of secondary water, 3 parts of potassium persulfate, 1 part of 2,2'-azobis(2-imidazoline) dihydrochloride, 2 parts of dodecyltrimethylammonium bromide, 2 parts of lauryl alcohol polyether and 1 part of EDTA 2Na are dissolved uniformly at 300 rpm, nitrogen is introduced for 2 h to remove oxygen, and a water phase is obtained;

[0059] S2. Using mechanical stirring, 130 parts of 3# white oil, 60 parts of 10# white oil and 80 parts of 15# white oil are added to a reaction bottle at 300 rpm, then 30 parts of Span 80, 4 parts of Tween 81 and 1 part of Tween 80 are added and stirred until the oil phase is clear and uniform, and an oil phase is obtained;

[0060] S3. The water phase is poured into the oil phase, a high-speed homogenizer is used, the rotating speed is controlled at 20,000 rpm, and emulsification is performed for 15 minutes, finally the viscosity of the reaction system is emulsified to 2302 cp, and a uniform emulsion is obtained;

[0061] S4. The uniform emulsion is connected to the reactor, nitrogen is introduced to below the emulsion surface, oxygen removal is continued for 30 minutes, mechanical stirrer is used for continuous stirring during the period, the rotating speed is controlled at 250 rpm, sodium sulfite, ammonium sulfite are prepared into 5% solution in the proportion of 1:1, micro-injection pump is used to inject into the reaction system at the speed of 1 mL / h, the reaction temperature is controlled at 50°C, the reaction is continued for 3 h to obtain the product.

[0062] Comparative Example 1

[0063] The comparative example is basically the same as example 1, except that dodecyltrimethylammonium bromide and lauryl alcohol polyether are not added, so as to verify the influence of the cationic surfactant on the synthesis reaction of the DMC system reverse-phase emulsion thickening agent.

[0064] Comparative Example 2

[0065] The comparative example provides an existing reverse-phase emulsion thickening agent product, the production manufacturer is 835 of Shandong Nuoer Biological Science and Technology Co., Ltd.

[0066] Comparative Example 3

[0067] This comparative example provides a prior art inverse emulsion viscosifier product, which is an emulsion produced by Guanghan Huaxing New Technology Development Institute.

[0068] Comparative Example 4

[0069] This comparative example is basically the same as Example 1, except that lauryl alcohol polyether and dodecyl trimethyl ammonium bromide are replaced by fatty alcohol polyoxyethylene ether AEO-9 and octadecyl trimethyl ammonium chloride to verify the influence of other cationic surfactants on the synthesis reaction of the DMC system inverse emulsion viscosifier.

[0070] In order to better understand the present application, the following will be further described by testing the products of the above examples and comparative examples.

[0071] A 20% HCl acid solution is prepared, including 20% HCl and 3% heterocyclic quaternary ammonium salt corrosion inhibitor, and 1%, 1.2%, 2.5%, and 3% of the products of Examples 1-3 and Comparative Examples 1-4 are added respectively, and a viscosity test is performed at room temperature using a viscometer, and the test results are shown in Table 1:

[0072]

[0073] The temperature resistance performance in the 20% HCl acid solution is shown in Table 2:

[0074]

[0075] Please refer to Figure 1 , Figure 1 The acid solution product diagram prepared from the product of Example 1, as can be seen from the test results, Examples 1-3 can all obtain effective products, among which the viscosity-increasing effect of Example 1 is the best, and the temperature resistance is the best, which can reach 200℃. Comparative Examples 1 and 4 attempt to use lauryl alcohol polyether and dodecyl trimethyl ammonium bromide as water phase surfactants, and are replaced by other cationic surfactants, due to the problem of reaction polymerization, the target product cannot be obtained smoothly, and the reaction fails. Comparative Examples 2 and 3 are commercially available existing products, the viscosity of the products of Comparative Examples 2 and 3 decreases obviously at a temperature of 160℃, and the temperature resistance is not as good as Examples 1-3. Please refer to Figures 2-3 , Figure 2 The product state diagram of Example 1 after temperature resistance test, Figure 3 The product state diagram of Comparative Example 2, as can be seen from the diagram, the product of Example 1 is stable in shape and uniform in appearance, the product of Comparative Example 2 is seriously layered and caked, and has appeared incompatibility, indicating that the temperature resistance of Comparative Example 2 is poor, while the product of the present application has good temperature resistance.

[0076] The present application solves the problem that the current DMC homopolymer emulsion cannot be effectively synthesized. The product prepared by Example 1 is shown in Figure 4 , the molecular formula is , the infrared spectrum is shown in Figure 5 , and the product deuterium water phase 1H-NMR diagram is shown in Figure 6 .

[0077] The core difficulty of the industrial application of pure DMC (methacryloyloxyethyl trimethyl ammonium chloride) as a single monomer for reverse phase emulsion homopolymerization lies in the strong hydrophilicity and high charge density characteristics of the monomer itself, which is in conflict with the physical and chemical requirements of the reverse phase emulsion system. The technical bottlenecks are analyzed from the following three aspects:

[0078] First, the electrostatic repulsion is insufficient and the droplets are coalesced: each repeat unit on the DMC homopolymer chain carries a quaternary ammonium salt cation group (+N(CH3)3), resulting in a Zeta potential on the surface of the emulsion droplets higher than +50 mV. High charge density should enhance the electrostatic repulsion between droplets, but due to the low dielectric constant of the oil phase (ε≈2), the electrostatic shielding effect is significant, and the actual repulsion energy barrier is less than 10 kT (much lower than the required 25 kT). Therefore, the emulsified droplets are prone to coalescence during the emulsification process and the reaction process.

[0079] Second, the reverse phase emulsion nucleation relies on monomer droplets as reaction sites, but the interfacial tension between DMC aqueous solution and oil phase is high (>40 mN / m), the droplet size distribution is wide (PDI>0.5), and the reaction rate after initiation is not uniform, part of the droplets gel prematurely, please refer to Figures 7-8 , Figure 7 for the optical micrograph of premature gelation, Figure 8 for the emulsion state under 50 times optical microscope, from the figure it can be observed that a large number of droplets coalesce.

[0080] Third, emulsification problem: traditional Span / Tween type non-ionic emulsifiers (HLB 4-6) rely on steric hindrance stabilization mechanism, but the hydrophilic segment (polyoxyethylene) and the cationic group exist charge repulsion, resulting in reduced adsorption efficiency at the oil-water interface. Stable W / O emulsion requires low HLB (4-6), but DMC strong hydrophilicity requires high HLB (>10) to reduce interfacial tension. The two cannot be compatible, and the conventional emulsifier compounding fails.

[0081] Based on this, the present application adds two cationic monomers, dodecyl trimethyl ammonium bromide and lauryl alcohol polyether, in the aqueous phase, uses polymerization method, uses homogenizer as mechanical emulsification scheme, and cooperates with multiple emulsifiers and multiple types of white oil compounding to improve the "core-shell structure stability" of water-in-oil, greatly improve the viscosity of the emulsion, and improve the overall stability of the reaction system.

[0082] The embodiments described above are only part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

Claims

1. An inverse emulsion gelling agent for use in super high temperature gelled acid, characterized in that, The methacryloyloxyethyl trimethyl ammonium chloride monomer is prepared by a reverse emulsion polymerization reaction, and the reverse emulsion comprises a water phase and an oil phase; The water phase raw materials comprise 350-450 parts of methacryloyloxyethyl trimethyl ammonium chloride monomer, 4-9 parts of an initiator, 1-2 parts of an auxiliary agent, 220-260 parts of secondary water and a water phase emulsifier by mass fraction; the water phase emulsifier is a combination of 1-5 parts of dodecyl trimethyl ammonium bromide and 1-5 parts of lauryl alcohol polyether; the initiator comprises a combination of 3-5 parts of an oxidized initiator and 1-4 parts of an azo initiator by mass fraction; The oil phase raw materials comprise 220-260 parts of an oil medium and 25-50 parts of an oil phase emulsifier; The reverse emulsion polymerization reaction is initiated by dropwise adding an aqueous solution of a reduced initiator.

2. The thickening agent of claim 1, wherein, The purity of the methacryloyloxyethyl trimethyl ammonium chloride monomer is 78-80%.

3. The thickening agent of claim 1, wherein, The oxidized initiator comprises one or more of potassium persulfate, ammonium persulfate and sodium persulfate, and the azo initiator comprises one or more of 2,2'-azobis(2-imidazoline) dihydrochloride, azobisdimethylvaleronitrile and azobisdimethylamidin.

4. The thickening agent of claim 1, wherein, The auxiliary agent is disodium EDTA.

5. The thickening agent of claim 1, wherein, The oil medium comprises one or more of 3# white oil, 10# white oil and 15# white oil.

6. The thickening agent of claim 1, wherein, The oil phase emulsifier comprises a combination of 20-35 parts of Span 80 and 5-15 parts of a Tween emulsifier by mass fraction, and the Tween emulsifier comprises one or more of Tween 80, Tween 81 and Tween 60.

7. The thickening agent of claim 1, wherein, The reduced initiator comprises one or more of ammonium sulfite, sodium sulfite, sodium metabisulfite and potassium metabisulfite.

8. A process for the preparation of the inverse emulsion gelling agent for super high gel acid of any one of claims 1 to 7, characterized in that, The preparation method comprises the following steps: S1. The water phase raw materials are mixed and stirred to be uniform, and deoxygenation treatment is performed to obtain a water phase; S2. The oil phase raw materials are stirred until the oil phase is clear and uniform to obtain an oil phase; S3. The water phase is added to the oil phase, and emulsification is performed until the viscosity of the reaction system is 2200-2500 cp to obtain a uniform emulsion; S4. The uniform emulsion is subjected to deoxygenation treatment, and an aqueous solution of a reduced initiator with a concentration of 1-5% is added to initiate a polymerization reaction to obtain an acid liquid reverse emulsion thickening agent for super-high-temperature gelling acid.

9. The method of claim 8, wherein, In the step S1, ultrasonic waves are used in combination with mechanical stirring at a speed of 300 rpm; and the deoxygenation treatment is performed by introducing nitrogen for 2-3 h.

10. The method of claim 8, wherein, In the step S4, the deoxygenation treatment is performed by introducing nitrogen for 20-30 min while stirring at a speed of 150-250 rpm; the aqueous solution of the reduced initiator is injected by a microsyringe pump at a speed of 5-10 mL / h, and the reaction temperature is controlled at 35-60℃, and the reaction time is 3-5 h.

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