Composite blocking remover as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to a composite blocking remover and a preparation method and application thereof. The composite blocking remover comprises the following components in percentage by weight, comprising the following components in percentage by weight: 5 to 8 percent of hydrochloric acid, 1 to 3 percent of fluoboric acid, 0.5 to 2 percent of acetic acid, 0.5 to 1 percent of dodecyl trimethyl ammonium chloride, 0.1 to 0.3 percent of potassium chloride, 0.3 to 0.8 percent of sodium erythorbate, 0.2 to 0.5 percent of tetrasodium glutamate diacetate, 1 to 2 percent of ethylenediamine tetraacetic acid, 0.1 to 0.2 percent of inositol hexaphosphate, 0.1 to 0.2 percent of cocoanut fatty acid diethanolamide, 0.3 to 0.5 percent of sodium dodecyl benzene sulfonate, 0.3 to 0.5 percent of dimethyl diallyl ammonium chloride, 0.1 to 0.2 percent of ethylene glycol monobutyl ether and the balance of water. The composite blocking remover provided by the invention does not generate the problem of secondary precipitation, slows down the reaction speed of acid rocks, effectively pushes a blocking removal measure solution into the deep part of a stratum, enlarges the blocking removal radius, realizes deep treatment of the stratum, improves the acidification effect, and prolongs the effective action time of acidification.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a composite unblocking agent, its preparation method, and its application. Background Technology

[0002] During oilfield development, contamination and blockage of oil and water wells have affected their normal production and maintenance, leading to reduced oil production and insufficient water injection. Acidizing, as an effective measure to remove contamination and blockage, can eliminate contamination damage in the wellbore and near-wellbore area, thereby increasing oil production and water injection volume.

[0003] Due to the reservoir lithology and the different contamination factors in the wellbore and near-wellbore zone, in order to meet the requirements of conventional acidizing of the reservoir lithology, ordinary acid solutions require the use of pretreatment fluids, main acid solutions, and post-treatment fluids to prevent precipitation such as calcium fluoride and sodium fluorosilicate. Among them, the main acid solution is usually a mixture of different acids such as hydrochloric acid, hydrofluoric acid, and ammonium bifluoride. The acidizing process involves many steps and is complex, requiring high standards for the acidizing construction site. At the same time, the main acid solution is prone to secondary precipitation problems in acidizing projects, which cannot guarantee the acidizing effect.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a composite unblocking agent, its preparation method, and its application. This composite unblocking agent eliminates the need for pretreatment and posttreatment solutions during the acidification process, thus solving the problem of secondary precipitation of the main acid solution after acidification and ensuring the acidification effect.

[0006] To overcome the shortcomings of the prior art, the present invention provides the following technical solution:

[0007] A composite unblocking agent, by weight percentage, comprises the following components: 5-8 wt% hydrochloric acid, 1-3 wt% fluoroboric acid, 0.5-2 wt% acetic acid, 0.5-1 wt% dodecyltrimethylammonium chloride, 0.1-0.3 wt% potassium chloride, 0.3-0.8 wt% sodium isoVC, 0.2-0.5 wt% tetrasodium diacetate of glutamic acid, 1-2 wt% ethylenediaminetetraacetic acid, 0.1-0.2 wt% inositol hexaphosphate, 0.1-0.2 wt% coconut oil fatty acid diethanolamide, 0.3-0.5 wt% sodium dodecylbenzenesulfonate, 0.3-0.5 wt% dimethyl diallyl ammonium chloride, 0.1-0.2 wt% ethylene glycol monobutyl ether, and the remainder being water.

[0008] Further, by weight percentage, it comprises the following components: 6.5 wt% hydrochloric acid, 2 wt% fluoroboric acid, 1 wt% acetic acid, 1 wt% dodecyltrimethylammonium chloride, 0.2 wt% potassium chloride, 0.5 wt% sodium isoVC, 0.3 wt% tetrasodium diacetate of glutamic acid, 1.5 wt% ethylenediaminetetraacetic acid, 0.2 wt% inositol hexaphosphate, 0.1 wt% coconut oil fatty acid diethanolamide, 0.5 wt% sodium dodecylbenzenesulfonate, 0.5 wt% dimethyl diallyl ammonium chloride, 0.2 wt% ethylene glycol monobutyl ether, and the remainder being water.

[0009] Furthermore, it also includes 1-2 wt% of corrosion inhibitor; the corrosion inhibitor is a quaternary ammonium salt corrosion inhibitor.

[0010] Furthermore, the quaternary ammonium salt corrosion inhibitor is a compound of hexamethylenetetramine, propynyl alcohol, methanol and triallyl quaternary ammonium salt FTDY with a solid content of 75-85% in a weight ratio of (1-2.5):(0.5-1.5):(5-8):20.

[0011] Furthermore, it also includes 3-5 wt% viscosity reducer.

[0012] Furthermore, the viscosity reducer is a heavy oil chemical phlegm-and-puff agent.

[0013] In addition, the present invention also provides a method for preparing the composite unblocking agent as described above, comprising the following steps:

[0014] S1. Mix acetic acid and ethylenediaminetetraacetic acid in a certain proportion, add tetrasodium glutamate diacetate, and stir until completely dissolved to obtain solution A;

[0015] S2. Mix hydrochloric acid, fluoroboric acid, dodecyltrimethylammonium chloride, inositol hexaphosphate, coconut oil fatty acid diethanolamide and water in proportion, then add potassium chloride, sodium isoVC, sodium dodecylbenzenesulfonate, dimethyl diallyl ammonium chloride and ethylene glycol monobutyl ether and stir until completely dissolved to obtain solution B.

[0016] S3. Pour solution A into solution B and mix well to obtain the composite unblocking agent.

[0017] In addition, the present invention also provides the application of the composite unblocking agent as described above in oilfield unblocking.

[0018] Compared with the prior art, the technical solution of the present invention has at least the following technical effects:

[0019] The composite unblocking agent of this invention overcomes the problem of requiring multiple acid solutions for acidizing operations. During acidizing, there is no need for pretreatment or post-treatment fluids; the composite unblocking agent of this invention can be used directly. Furthermore, the composite unblocking agent of this invention does not cause secondary precipitation, slows down the acid-rock reaction rate, effectively pushes the unblocking solution into the deep formation, expands the unblocking radius, achieves deep formation treatment, improves acidizing effect, and extends the effective acidizing time. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0021] Figure 1 The organic scale dissolution of the composite unblocking agent prepared in Example 1;

[0022] Figure 2 The dissolution of organic scale in a composite unblocking agent for ordinary acid solutions;

[0023] Figure 3 The thick oil emulsification and viscosity reduction of the composite unblocking agent prepared in Example 1;

[0024] Figure 4 This describes the viscosity reduction effect of emulsifying heavy oils in ordinary acid solutions.

[0025] Figure 5 The residual acid secondary precipitation of the composite unblocking agent prepared in Example 1;

[0026] Figure 6 This describes the secondary precipitation of residual acid in ordinary acid solutions.

[0027] Figure 7 The corrosion of the steel sheet by the composite unblocking agent prepared in Example 4 is shown.

[0028] Figure 8 This shows the corrosion of steel sheets by ordinary acid. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0030] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0031] According to a first aspect of the present invention, a composite unblocking agent is provided, comprising, by weight percentage, the following components: 5-8 wt% hydrochloric acid (e.g., 5 wt%, 6 wt%, 7 wt%, 8 wt%), 1-3 wt% fluoroboric acid (e.g., 1 wt%, 2 wt%, 3 wt%), 0.5-2 wt% acetic acid (e.g., 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%), 0.5-1 wt% dodecyltrimethylammonium chloride (e.g., 0.5 wt%, 1 wt%), 0.1-0.3 wt% potassium chloride (e.g., 0.1 wt%, 0.2 wt%, 0.3 wt%), and 0.3-0.8 wt% sodium isoVC (e.g., 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%). 0.7wt%, 0.8wt%), tetrasodium glutamate diacetate 0.2-0.5wt% (e.g., 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%), ethylenediaminetetraacetic acid 1-2wt% (e.g., 1wt%, 1.5wt%, 2wt%), inositol hexaphosphate 0.1-0.2wt% (e.g., 0.1wt%, 0.2wt%), coconut oil fatty acid diethanolamide 0.1-0.2wt% (e.g., 0.1wt%, 0.2wt%), sodium dodecylbenzenesulfonate 0.3-0.5wt% (e.g., 0.3wt%, 0.4wt%, 0.5wt%), dimethyl diallyl ammonium chloride 0.3-0.5wt%, ethylene glycol monobutyl ether 0.1-0.2wt%, the remainder being water.

[0032] The composite unblocking agent of the present invention does not separate into layers or produce precipitation. Under the synergistic effect of each component, it contains chelating, anti-swelling, and water-locking components, and will not cause secondary precipitation. It can prevent equipment and pipe corrosion, prevent secondary precipitation of acid, prevent clay migration and water lock damage, so there is no need to use pretreatment liquid and post-treatment liquid.

[0033] Specifically, the synergistic effects are as follows: Acetic acid components have a dissolving effect, and when combined with tetrasodium glutamate diacetate, ethylenediaminetetraacetic acid, and sodium iso-VC, they also have a chelating effect, chelating calcium, iron, magnesium, and other ions; dodecyltrimethylammonium chloride, dimethyl diallyl ammonium chloride, and potassium chloride have the effect of preventing clay swelling, and when combined, they can improve the anti-swelling ability and also have the ability to prolong the anti-swelling effect due to water erosion. Coconut oil fatty acid diethanolamide has the ability to clean and resist hard water. When combined with ethylene glycol monobutyl ether, it can increase the water-locking effect. Inositol hexaphosphate and triallyl quaternary ammonium salt have a corrosion-inhibiting effect, and when combined with tetrasodium glutamate diacetate and ethylenediaminetetraacetic acid, it also has a chelating effect. Sodium dodecylbenzenesulfonate has a cleaning effect, but the high salinity of oilfield formation water affects its effectiveness. When combined with coconut oil fatty acid diethanolamide, it can increase the cleaning effect and is not affected by the high salinity of water. When combined with ethylene glycol monobutyl ether, it can also reduce surface tension.

[0034] To further optimize the effect of the composite unblocking agent, this invention studied the influence of different proportions of various components on its effect, and obtained a better component ratio as follows: by weight percentage, it includes the following components: hydrochloric acid 6.5wt%, fluoroboric acid 2wt%, acetic acid 1wt%, dodecyltrimethylammonium chloride 1wt%, potassium chloride 0.2wt%, sodium isoVC 0.5wt%, tetrasodium diacetate of glutamic acid 0.3wt%, ethylenediaminetetraacetic acid 1.5wt%, inositol hexaphosphate 0.2wt%, coconut oil fatty acid diethanolamide 0.1wt%, sodium dodecylbenzenesulfonate 0.5wt%, dimethyl diallyl ammonium chloride 0.5wt%, ethylene glycol monobutyl ether 0.2wt%, and the remainder is water.

[0035] In the above-mentioned composite unblocking agent, as a preferred embodiment, it further includes 1-2 wt% of a corrosion inhibitor. The corrosion inhibitor is a quaternary ammonium salt corrosion inhibitor.

[0036] More preferably, the quaternary ammonium salt corrosion inhibitor is prepared by compounding hexamethylenetetramine (HXMT), propynyl alcohol, methanol, and triallyl quaternary ammonium salt (FTDY) with a solid content of 75-85% in a weight ratio of (1-2.5):(0.5-1.5):(5-8):20. The preparation method is as follows: propynyl alcohol, methanol, and triallyl quaternary ammonium salt (FTDY) with a solid content of 75-85% are mixed in the specified proportion, then hexamethylenetetramine is added, and the mixture is stirred until completely dissolved to obtain the corrosion inhibitor.

[0037] In the above-mentioned composite unblocking agent, as a preferred embodiment, the components of the present invention further include 3-5 wt% of a viscosity reducer. More preferably, the viscosity reducer is a heavy oil chemical huff and puff agent. The heavy oil chemical huff and puff agent in the present invention can be the heavy oil chemical huff and puff agent of the authorized patent with publication number CN104403650B, or it can be prepared by conventional preparation methods, which will not be described in detail here.

[0038] According to a second aspect of the present invention, a method for preparing the above-mentioned composite unblocking agent is provided, comprising the following steps:

[0039] S1. Mix acetic acid and ethylenediaminetetraacetic acid in a certain proportion, add tetrasodium glutamate diacetate, and stir until completely dissolved to obtain solution A;

[0040] S2. Mix hydrochloric acid, fluoroboric acid, dodecyltrimethylammonium chloride, inositol hexaphosphate, coconut oil fatty acid diethanolamide and water in proportion, then add potassium chloride, sodium isoVC, sodium dodecylbenzenesulfonate, dimethyl diallyl ammonium chloride and ethylene glycol monobutyl ether and stir until completely dissolved to obtain solution B.

[0041] S3. Pour solution A into solution B and mix well to obtain the composite unblocking agent.

[0042] The corrosion inhibitor and viscosity reducer mentioned in this invention can be added sequentially to the composite unblocking agent obtained in step S3 and stirred evenly.

[0043] According to a third aspect of the present invention, the application of the above-described composite unblocking agent in oilfield unblocking is provided. Compared with other acids, the composite unblocking agent of the present invention does not require timely backflow during application.

[0044] The present invention will now be described in detail with reference to embodiments thereof. These examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present invention without departing from its scope or spirit. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present invention encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0045] In the embodiments of the present invention, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0046] Example 1

[0047] This embodiment provides a composite unblocking agent with the following component contents: hydrochloric acid 6.5wt%, fluoroboric acid 2wt%, acetic acid 1wt%, dodecyltrimethylammonium chloride 1wt%, potassium chloride 0.2wt%, sodium isoVC 0.5wt%, tetrasodium diacetate of glutamic acid 0.3wt%, ethylenediaminetetraacetic acid 1.5wt%, inositol hexaphosphate 0.2wt%, coconut oil fatty acid diethanolamide 0.1wt%, sodium dodecylbenzenesulfonate 0.5wt%, dimethyl diallyl ammonium chloride 0.5wt%, ethylene glycol monobutyl ether 0.2wt%, and the remainder is water.

[0048] The preparation method is as follows:

[0049] S1. Mix acetic acid and ethylenediaminetetraacetic acid in a certain proportion, add tetrasodium glutamate diacetate, and stir until completely dissolved to obtain solution A;

[0050] S2. Mix hydrochloric acid, fluoroboric acid, dodecyltrimethylammonium chloride, inositol hexaphosphate, coconut oil fatty acid diethanolamide and water in proportion, then add potassium chloride, sodium isoVC, sodium dodecylbenzenesulfonate, dimethyl diallyl ammonium chloride and ethylene glycol monobutyl ether and stir until completely dissolved to obtain solution B.

[0051] S3. Pour solution A into solution B and mix well to obtain the composite unblocking agent of this embodiment.

[0052] Example 2

[0053] This embodiment provides a composite unblocking agent with the following component contents: hydrochloric acid 5wt%, fluoroboric acid 1wt%, acetic acid 0.5wt%, dodecyltrimethylammonium chloride 0.5wt%, potassium chloride 0.1wt%, sodium isoVC 0.3wt%, tetrasodium diacetate of glutamic acid 0.2wt%, ethylenediaminetetraacetic acid 1wt%, inositol hexaphosphate 0.1wt%, coconut oil fatty acid diethanolamide 0.1wt%, sodium dodecylbenzenesulfonate 0.3wt%, dimethyl diallyl ammonium chloride 0.3wt%, ethylene glycol monobutyl ether 0.1%, and the remainder being water.

[0054] The preparation method is as follows:

[0055] S1. Mix acetic acid and ethylenediaminetetraacetic acid in a certain proportion, add tetrasodium glutamate diacetate, and stir until completely dissolved to obtain solution A;

[0056] S2. Mix hydrochloric acid, fluoroboric acid, dodecyltrimethylammonium chloride, inositol hexaphosphate, coconut oil fatty acid diethanolamide and water in proportion, then add potassium chloride, sodium isoVC, sodium dodecylbenzenesulfonate, dimethyl diallyl ammonium chloride and ethylene glycol monobutyl ether and stir until completely dissolved to obtain solution B.

[0057] S3. Pour solution A into solution B and mix well to obtain the composite unblocking agent of this embodiment.

[0058] Example 3

[0059] This embodiment provides a composite unblocking agent with the following component contents: hydrochloric acid 8wt%, fluoroboric acid 3wt%, acetic acid 2wt%, dodecyltrimethylammonium chloride 1wt%, potassium chloride 0.3wt%, sodium isoVC 0.8wt%, tetrasodium diacetate of glutamic acid 0.5wt%, ethylenediaminetetraacetic acid 2wt%, inositol hexaphosphate 0.2wt%, coconut oil fatty acid diethanolamide 0.2wt%, sodium dodecylbenzenesulfonate 0.5wt%, dimethyl diallyl ammonium chloride 0.5wt%, ethylene glycol monobutyl ether 0.2%, and the remainder being water.

[0060] The preparation method is as follows:

[0061] S1. Mix acetic acid and ethylenediaminetetraacetic acid in a certain proportion, add tetrasodium glutamate diacetate, and stir until completely dissolved to obtain solution A;

[0062] S2. Mix hydrochloric acid, fluoroboric acid, dodecyltrimethylammonium chloride, inositol hexaphosphate, coconut oil fatty acid diethanolamide and water in proportion, then add potassium chloride, sodium isoVC, sodium dodecylbenzenesulfonate, dimethyl diallyl ammonium chloride and ethylene glycol monobutyl ether and stir until completely dissolved to obtain solution B.

[0063] S3. Pour solution A into solution B and mix well to obtain the composite unblocking agent of this embodiment.

[0064] Example 4

[0065] This embodiment provides a composite unblocking agent with the following component contents: hydrochloric acid 6.5wt%, fluoroboric acid 2wt%, acetic acid 1wt%, dodecyltrimethylammonium chloride 1wt%, potassium chloride 0.2wt%, sodium isoVC 0.5wt%, tetrasodium diacetate of glutamic acid 0.3wt%, ethylenediaminetetraacetic acid 1.5wt%, inositol hexaphosphate 0.2wt%, coconut oil fatty acid diethanolamide 0.1wt%, sodium dodecylbenzenesulfonate 0.5wt%, dimethyl diallyl ammonium chloride 0.4wt%, ethylene glycol monobutyl ether 0.1%, corrosion inhibitor 2wt%, and the remainder is water.

[0066] Preparation of corrosion inhibitor: Mix propynyl alcohol, methanol and triallyl quaternary ammonium salt (FTDY) with a solid content of 75-85% in a certain proportion, add hexamethylenetetramine, and stir until completely dissolved to obtain the corrosion inhibitor.

[0067] Preparation of composite unblocking agent:

[0068] S1. Mix acetic acid and ethylenediaminetetraacetic acid in a certain proportion, add tetrasodium glutamate diacetate, and stir until completely dissolved to obtain solution A;

[0069] S2. Mix hydrochloric acid, fluoroboric acid, dodecyltrimethylammonium chloride, inositol hexaphosphate, coconut oil fatty acid diethanolamide and water in proportion, then add potassium chloride, sodium isoVC, sodium dodecylbenzenesulfonate, dimethyl diallyl ammonium chloride and ethylene glycol monobutyl ether and stir until completely dissolved to obtain solution B.

[0070] S3. Pour solution A into solution B, mix well, and then add corrosion inhibitor to obtain the composite unblocking agent of this embodiment.

[0071] Experimental Example 1

[0072] The composite unblocking agent prepared in Example 1 and ordinary acid solutions (hydrochloric acid and terrine used in SY / T 5405-2019 "Test Methods and Evaluation Indicators for Corrosion Inhibitors" (evaluation index 5.3 in the standard)) were subjected to comparative experiments on organic scale dissolution, heavy oil emulsification and viscosity reduction, and residual acid secondary precipitation. The organic scale dissolution of the composite unblocking agent was as follows: Figure 1 As shown, the dissolution of organic scale in ordinary acid solutions is as follows: Figure 2 As shown; the thick oil emulsification and viscosity reduction of the composite unblocking agent is as follows. Figure 3 As shown, the viscosity reduction of heavy oil emulsification in ordinary acid solutions is as follows: Figure 4 As shown; the secondary precipitation of residual acid in the composite unblocking agent is as follows. Figure 5 As shown, the secondary precipitation of residual acid in ordinary acid solutions is as follows: Figure 6 As shown; the test results are shown in Table 1:

[0073] Table 1

[0074]

[0075]

[0076] Experimental Example 2

[0077] A comparative experiment was conducted on the corrosion of N80 steel sheets at 50℃ for 72 hours using the composite unblocking agent prepared in Example 4 and ordinary acid solutions (hydrochloric acid and terrine used in SY / T 5405-2019 "Test Methods and Evaluation Indicators for Corrosion Inhibitors" (evaluation index 5.3 in the standard)). The corrosion rate was determined according to the specifications in SY / T5405-2019 "Test Methods and Evaluation Indicators for Corrosion Inhibitors". The corrosion effect of the composite unblocking agent on the steel sheets is as follows: Figure 7 As shown, the corrosion of steel sheets by ordinary acid solutions is as follows: Figure 8 As shown; Experimental results: The corrosion rate of the composite unblocking agent prepared in Example 4 on the steel sheet was 0.4251 g / m. 2 The corrosion rate of ordinary acid on steel sheets is 1.7811 g / m. 2 .h

[0078] The foregoing has described and evaluated some embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, still fall within the protection scope of the present invention.

Claims

1. A composite unblocking agent, characterized in that, By weight percentage, it comprises the following components: hydrochloric acid 5–8 wt%, fluoroboric acid 1–3 wt%, acetic acid 0.5–2 wt%, dodecyltrimethylammonium chloride 0.5–1 wt%, potassium chloride 0.1–0.3 wt%, sodium isoVC 0.3–0.8 wt%, tetrasodium diacetate of glutamic acid 0.2–0.5 wt%, ethylenediaminetetraacetic acid 1–2 wt%, inositol hexaphosphate 0.1–0.2 wt%, coconut oil fatty acid diethanolamide 0.1–0.2 wt%, sodium dodecylbenzenesulfonate 0.3–0.5 wt%, dimethyl diallyl ammonium chloride 0.3–0.5 wt%, ethylene glycol monobutyl ether 0.1–0.2 wt%, and the remainder being water.

2. The composite unblocking agent according to claim 1, characterized in that, By weight percentage, it comprises the following components: 6.5 wt% hydrochloric acid, 2 wt% fluoroboric acid, 1 wt% acetic acid, 1 wt% dodecyltrimethylammonium chloride, 0.2 wt% potassium chloride, 0.5 wt% sodium iso-VC, 0.3 wt% tetrasodium diacetate of glutamic acid, 1.5 wt% ethylenediaminetetraacetic acid, 0.2 wt% inositol hexaphosphate, 0.1 wt% coconut oil fatty acid diethanolamide, 0.5 wt% sodium dodecylbenzenesulfonate, 0.5 wt% dimethyl diallyl ammonium chloride, 0.2 wt% ethylene glycol monobutyl ether, and the remainder is water.

3. The composite unblocking agent according to claim 1 or 2, characterized in that, It also includes 1-2 wt% of corrosion inhibitor; the corrosion inhibitor is a quaternary ammonium salt corrosion inhibitor.

4. The composite unblocking agent according to claim 3, characterized in that, The quaternary ammonium salt corrosion inhibitor is a compound of hexamethylenetetramine, propynyl alcohol, methanol and triallyl quaternary ammonium salt FTDY with a solid content of 75-85% in a weight ratio of (1-2.5):(0.5-1.5):(5-8):

20.

5. The composite unblocking agent according to claim 1 or 2, characterized in that, It also includes 3-5 wt% viscosity reducer.

6. The composite unblocking agent according to claim 5, characterized in that, The viscosity reducer is a heavy oil chemical phlegm-and-flushing agent.

7. A method for preparing a composite unblocking agent as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Mix acetic acid and ethylenediaminetetraacetic acid in a certain proportion, add tetrasodium glutamate diacetate, and stir until completely dissolved to obtain solution A; S2. Mix hydrochloric acid, fluoroboric acid, dodecyltrimethylammonium chloride, inositol hexaphosphate, coconut oil fatty acid diethanolamide and water in proportion, then add potassium chloride, sodium isoVC, sodium dodecylbenzenesulfonate, dimethyl diallyl ammonium chloride and ethylene glycol monobutyl ether and stir until completely dissolved to obtain solution B. S3. Pour solution A into solution B and mix well to obtain the composite unblocking agent.

8. The application of the composite unblocking agent as described in any one of claims 1-6 in oilfield unblocking.

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