Slow-release solid self-generating acid, and preparation method and application thereof

Abstract

The application discloses a slow-release solid self-generating acid and a preparation method and application thereof, and belongs to the technical field of oil field chemical additives. 氯乙酸酐 ∶n 叔胺 The molar ratio of chloroacetic anhydride to tertiary amine is 1:2.0-2.2, and the tertiary amine is slowly added into the mixture; in step S2, the mixed solution in step S1 is heated to a reaction temperature, and after sufficient reflux reaction, the ethyl acetate is removed by rotary evaporation; in step S3, the product obtained in step S2 is soaked in an acetone solution, the product is cleaned, and vacuum drying is performed until the weight is constant, so that the slow-release solid self-generating acid is finally obtained. The method has high yield, low cost and simple production process. The prepared slow-release solid self-generating acid has excellent slow-release hydrogen ion performance, and has many advantages, such as convenient transportation and storage, low corrosion to pipeline equipment, slow acid generation speed, long effective distance and the like.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical additives technology, and in particular to a slow-release solid autogenous acid, its preparation method, and its application. Background Technology

[0002] With the large-scale exploitation and consumption of conventional oil and gas reservoirs, unconventional oil and gas resources with low permeability and ultra-low permeability, and high temperature in deep formations, such as tight sandstone gas, coalbed methane, and shale gas, urgently need to be developed and utilized. Acidizing is an important means of increasing production in oil and gas wells and increasing injection in water injection wells. In particular, many tight oil and gas reservoirs have been discovered in recent years. In the early stages of production, the output is very low or even non-existent, and acidizing is required to achieve a certain production value. At present, deep carbonate reservoirs often exhibit high or ultra-high temperature characteristics, which poses a significant challenge to the acid system during acidizing. Specifically, high temperatures accelerate the acid-rock reaction rate, making the effective action distance of the acid fluid increasingly shorter and difficult to achieve deep penetration of the reservoir.

[0003] Currently, existing acid systems still pose significant safety risks in terms of transportation and storage. Furthermore, the acid-rock reaction rate is rapid at high temperatures, leading to severe corrosion of the tubing and hindering the achievement of deep acidification at the far end of the reservoir and uneven etching of fracture walls. This severely restricts the efficient development of high-temperature and ultra-high-temperature carbonate reservoirs. Therefore, there is an urgent need for a solid autogenous acid that can be slowly released at high temperatures to solve these problems. Summary of the Invention

[0004] The present invention aims to provide a slow-release solid autogenous acid, its preparation method, and its application. When this solid autogenous acid hydrolyzes in water, it simultaneously produces carboxylic acids and surfactants. The surfactants adsorb onto the rock surface, reducing the acid-rock reaction rate between the organic acid and the rock, thereby further enhancing the slow-release capacity of the autogenous acid. It possesses excellent slow-release performance and numerous advantages, including ease of transportation and storage, low corrosiveness to pipelines and equipment, slow acid generation rate, and long effective range.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a sustained-release solid autogenous acid, the method comprising the following steps:

[0007] Step S1: Dissolve chloroacetic anhydride in ethyl acetate, then add chloroacetic anhydride to the tertiary amine according to the molar ratio n. 氯乙酸酐 :n 叔胺 The tertiary amine is slowly added dropwise at a ratio of 1:2.0 to 2.2 and mixed thoroughly.

[0008] Step S2: Heat the mixed solution from step S1 to the reaction temperature, reflux it thoroughly, and then remove ethyl acetate by rotary evaporation.

[0009] Step S3: Soak the product obtained in step S2 in acetone solution, wash the product, and vacuum dry to constant weight to finally obtain a slow-release solid autogenous acid.

[0010] Further, the tertiary amine includes one of dodecyl dimethyl tertiary amine, hexadecyl dimethyl tertiary amine, octadecyl dimethyl tertiary amine, or eicosyl dimethyl tertiary amine.

[0011] Furthermore, the molar ratio of chloroacetic anhydride to tertiary amine is 1:2.0, 1:2.1, or 1:2.2.

[0012] Furthermore, the reflux reaction conditions include: a reaction temperature of 70–80°C and a reaction time of 12–15 h.

[0013] Furthermore, the vacuum drying conditions include: a temperature of 40–50°C and a time of 8–10 hours.

[0014] The present invention also provides a slow-release solid autogenous acid, which is prepared by the above method.

[0015] The present invention also provides an application of the above-mentioned slow-release solid self-generating acid, wherein the application is the preparation of a slow-release self-generating acid solution.

[0016] Furthermore, the slow-release self-generating acid solution contains 5% to 30% by mass of slow-release solid self-generating acid, with the remainder being deionized water.

[0017] The technical effects and advantages of this invention are as follows:

[0018] (1) The present invention provides a method for preparing a slow-release solid autogenous acid, which has high yield, low cost and simple production process.

[0019] (2) Compared with traditional hydrochloric acid, which is corrosive, inconvenient to transport, and poses safety hazards, the slow-release solid autogenic acid prepared in this invention is an environmentally friendly solid autogenic acid EFSA (Environmentally friendly solid autogenic acid). This autogenic acid is solid, easy to transport and store, can be directly contacted with the skin, and has excellent slow-release hydrogen ion performance.

[0020] (3) The slow-release self-generated acid provided by the present invention can generate surfactants in the formation to form an adsorption layer on the rock surface, which can effectively reduce the acid-rock reaction and has a slowing effect.

[0021] (4) The slow-release self-generating acid solution provided by the present invention still has good acid generation ability at ultra-high temperature as an acidification solution, and can be applied to the development of ultra-high temperature reservoirs.

[0022] (5) The slow-release self-generating acid solution provided by the present invention still has good acid generation ability when the salinity of the water is low, and can be used for the development of high salinity reservoirs.

[0023] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for preparing a sustained-release solid autogenous acid according to the present invention;

[0025] Figure 2 The graph shows the concentration of self-generated acid solution prepared in Example 9 of this invention at different dosages and temperatures.

[0026] Figure 3 The graph shows the concentration of self-generated acid solution prepared in Example 10 of this invention at different mineralization levels. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] To address the shortcomings of existing technologies, this invention discloses a method for preparing a slow-release solid autogenous acid. Figure 1 This is a flowchart of a method for preparing a sustained-release solid autogenous acid according to the present invention, as shown below. Figure 1 As shown, the method includes the following steps:

[0029] Step S1: Dissolve chloroacetic anhydride in ethyl acetate, and then slowly add the tertiary amine dropwise according to a certain molar ratio and mix thoroughly.

[0030] In step S1 of the present invention, the tertiary amine includes, but is not limited to, one of dodecyl dimethyl tertiary amine, hexadecyl dimethyl tertiary amine, octadecyl dimethyl tertiary amine or eicosyl dimethyl tertiary amine.

[0031] The molar ratio n of chloroacetic anhydride to tertiary amine 氯乙酸酐 :n 叔胺 The ratio is 1:2.0 to 2.2.

[0032] Preferably, the molar ratio of chloroacetic anhydride to tertiary amine is 1:2.0, 1:2.1, or 1:2.2.

[0033] Step S2: Heat the mixed solution from step S1 to the reaction temperature and reflux it fully to obtain a pale yellow liquid, which is the ethyl acetate solution of the slow-release solid autogenous acid. Remove the ethyl acetate by rotary evaporation at 50°C to obtain a pale yellow viscous liquid.

[0034] In step S2 of the present invention, the reflux reaction conditions include: a reaction temperature of 70-80°C and a reaction time of 12-15 h.

[0035] Step S3: Soak the pale yellow viscous liquid obtained in step S2 in acetone solution for 1 day, wash the product, and vacuum dry to constant weight to finally obtain a slow-release solid autogenous acid for later use.

[0036] In step S3 of the present invention, the vacuum drying conditions include: a temperature of 40-50°C and a time of 8-10 hours.

[0037] The chemical reaction structure for synthesizing sustained-release solid autogenous acids is as follows:

[0038]

[0039] In the formula, R1 = dodecyl, tetradecyl, hexadecyl, octadecyl, or eicosyl, etc.

[0040] The present invention also discloses a slow-release solid autogenous acid, which is prepared by the above method.

[0041] This invention also discloses an application of a slow-release solid autogenous acid, specifically including the following steps:

[0042] A slow-release autogenous acid solution comprises 5%–30% slow-release solid autogenous acid by mass, with the remainder being deionized water. When the slow-release solid autogenous acid dissolves in water, it undergoes a hydrolysis reaction, generating carboxylic acid and a surfactant. The surfactant, due to adsorption, adheres to the rock surface, forming a protective layer that further reduces the H₂ content. + This increases the rate of acid-rock reaction with the rock, thereby improving the slowing ability of authigenic acid and achieving deep acidification.

[0043] The present invention will now be described in conjunction with specific embodiments:

[0044] Example 1:

[0045] Example 1 of this invention provides a method for preparing a slow-release solid autogenous acid, the method comprising the following steps:

[0046] Step S1: Dissolve chloroacetic anhydride in ethyl acetate, then add chloroacetic anhydride to dodecyl dimethyl tertiary amine in a molar ratio n. 氯乙酸酐 :n 叔胺The tertiary amine was slowly added dropwise at a ratio of 1:2.0 and mixed thoroughly.

[0047] Step S2: Heat the mixed solution from step S1 to 70°C and reflux for 13 hours to obtain a pale yellow liquid, which is the ethyl acetate solution of the slow-release solid autogenous acid. Remove the ethyl acetate by rotary evaporation to obtain a pale yellow viscous liquid.

[0048] Step S3: Soak the obtained pale yellow viscous liquid in acetone solution for 1 day, wash the product, and vacuum dry to constant weight. The yield of the slow-release solid autogenous acid is 85%.

[0049] Example 2:

[0050] Example 2 of the present invention provides a method for preparing a slow-release solid autogenous acid, the method comprising the following steps:

[0051] Step S1: Dissolve chloroacetic anhydride in ethyl acetate, then add chloroacetic anhydride to hexadecyl dimethyl tertiary amine in a molar ratio n. 氯乙酸酐 :n 叔胺 The tertiary amine was slowly added dropwise at a ratio of 1:2.1 and mixed thoroughly.

[0052] Step S2: Heat the mixed solution from step S1 to 70°C and reflux for 14 hours to obtain a pale yellow liquid, which is the ethyl acetate solution of the slow-release solid autogenous acid. Remove the ethyl acetate by rotary evaporation to obtain a pale yellow viscous liquid.

[0053] Step S3: Soak the obtained pale yellow viscous liquid in acetone solution for 1 day, wash the product, and vacuum dry to constant weight. The yield of the slow-release solid autogenous acid is 88%.

[0054] Example 3:

[0055] Example 3 of the present invention provides a method for preparing a slow-release solid autogenous acid, the method comprising the following steps:

[0056] Step S1: Dissolve chloroacetic anhydride in ethyl acetate, then add chloroacetic anhydride to tetradecyl dimethyl tertiary amine according to the molar ratio n. 氯乙酸酐 :n 叔胺 The tertiary amine was slowly added dropwise at a ratio of 1:2.2 and mixed thoroughly.

[0057] Step S2: The mixed solution from step S1 is heated to 75°C and refluxed for 13 hours to obtain a pale yellow liquid, which is the ethyl acetate solution of the slow-release solid autogenous acid. The ethyl acetate is removed by rotary evaporation to obtain a pale yellow viscous liquid.

[0058] Step S3: Soak the obtained pale yellow viscous liquid in acetone solution for 1 day, wash the product, and vacuum dry to constant weight. The yield of the slow-release solid autogenous acid is 93%.

[0059] Example 4:

[0060] Example 4 of this invention provides a method for preparing a slow-release solid autogenous acid, the method comprising the following steps:

[0061] Step S1: Dissolve chloroacetic anhydride in ethyl acetate, then add chloroacetic anhydride to octadecyl dimethyl tertiary amine in a molar ratio n. 氯乙酸酐 :n 叔胺 The tertiary amine was slowly added dropwise at a ratio of 1:2.1 and mixed thoroughly.

[0062] Step S2: Heat the mixed solution from step S1 to 75°C and reflux for 12 hours to obtain a pale yellow liquid, which is the ethyl acetate solution of the slow-release solid autogenous acid. Remove the ethyl acetate by rotary evaporation to obtain a pale yellow viscous liquid.

[0063] Step S3: Soak the obtained pale yellow viscous liquid in acetone solution for 1 day, wash the product, and vacuum dry to constant weight. The yield of the slow-release solid autogenous acid is 87%.

[0064] Example 5:

[0065] Example 5 of the present invention provides a method for preparing a slow-release solid autogenous acid, the method comprising the following steps:

[0066] Step S1: Dissolve chloroacetic anhydride in ethyl acetate, then add chloroacetic anhydride to dodecyl dimethyl tertiary amine in a molar ratio n. 氯乙酸酐 :n 叔胺 The tertiary amine was slowly added dropwise at a ratio of 1:2.0 and mixed thoroughly.

[0067] Step S2: Heat the mixed solution from step S1 to 80°C and reflux for 15 hours to obtain a pale yellow liquid, which is the ethyl acetate solution of the slow-release solid autogenous acid. Remove the ethyl acetate by rotary evaporation to obtain a pale yellow viscous liquid.

[0068] Step S3: Soak the obtained pale yellow viscous liquid in acetone solution for 1 day, wash the product, and vacuum dry to constant weight. The yield of the slow-release solid autogenous acid is 91%.

[0069] Example 6:

[0070] Example 6 of the present invention provides a method for preparing a slow-release solid autogenous acid, the method comprising the following steps:

[0071] Step S1: Dissolve chloroacetic anhydride in ethyl acetate, then add chloroacetic anhydride to dodecyl dimethyl tertiary amine in a molar ratio n. 氯乙酸酐 :n 叔胺 The tertiary amine was slowly added dropwise at a ratio of 1:2.1 and mixed thoroughly.

[0072] Step S2: Heat the mixed solution from step S1 to 80°C and reflux for 14 hours to obtain a pale yellow liquid, which is the ethyl acetate solution of the slow-release solid autogenous acid. Remove the ethyl acetate by rotary evaporation to obtain a pale yellow viscous liquid.

[0073] Step S3: Soak the obtained pale yellow viscous liquid in acetone solution for 1 day, wash the product, and vacuum dry to constant weight to finally obtain a slow-release solid autogenous acid with a yield of 95%.

[0074] Example 7:

[0075] Example 7 of the present invention provides a method for preparing a slow-release solid autogenous acid, the method comprising the following steps:

[0076] Step S1: Dissolve chloroacetic anhydride in ethyl acetate, then add chloroacetic anhydride to hexadecyl dimethyl tertiary amine in a molar ratio n. 氯乙酸酐 :n 叔胺 The tertiary amine was slowly added dropwise at a ratio of 1:2.2 and mixed thoroughly.

[0077] Step S2: Heat the mixed solution from step S1 to 80°C and reflux for 15 hours to obtain a pale yellow liquid, which is the ethyl acetate solution of the slow-release solid autogenous acid. Remove the ethyl acetate by rotary evaporation to obtain a pale yellow viscous liquid.

[0078] Step S3: Soak the obtained pale yellow viscous liquid in acetone solution for 1 day, wash the product, and vacuum dry to constant weight. The yield of the slow-release solid autogenous acid is 88%.

[0079] Examples 1-7 are based on the raw material setup for slow-release solid autogenous acid. The types and technical parameters of each raw material in Examples 1-7 are shown in Table 1.

[0080] Table 1. Types and technical parameters of each raw material in Examples 1-7

[0081]

[0082] Example 8:

[0083] The slow-release solid self-generating acid from Example 6 was prepared into an acid solution with a mass fraction of 30 wt% using deionized water. The acid reaction reaction of the product with marble was compared with the acid reaction reaction of hydrochloric acid and aminosulfonic acid. The experimental results are shown in Table 2. The results show that the solid acid of the present invention has excellent slow-release properties compared with hydrochloric acid and aminosulfonic acid.

[0084] Table 2. Retarding performance tests of different acids

[0085]

[0086] Example 9:

[0087] The slow-release solid self-generating acid from Example 6 was prepared into an acid solution with a mass fraction of 10–30 wt% using deionized water. The acid-generating capacity of the product at different temperatures was determined experimentally. The specific procedure was as follows: 100 mL of the solid self-generating acid solution was prepared in a clean beaker and heated at 25, 50, 90, 150, and 180 °C for 4 hours. Samples were taken for analysis, and the effective acid concentration released was calculated relative to the hydrochloric acid equivalent. The experimental results are as follows: Figure 2 The results showed that the solid acid of the present invention has a temperature resistance of up to 180℃.

[0088] Example 10:

[0089] The slow-release solid self-generating acid from Example 6 was used to prepare an acid solution with a mass fraction of 30 wt% using water with different mineralization levels. The acid-generating capacity of the product at different mineralization levels was then experimentally determined. The specific operation is as follows: using water with a mineralization of 2 × 10⁻⁶... 4 4×10 4 6×10 4 8×10 4 A 100 mL solid self-generating acid solution was prepared in a clean beaker using a composite saline solution with the following composition: 2.0 wt% KCl + 5.5 wt% NaCl + 0.45 wt% MgCl₂ + 0.55 wt% CaCl₂. The solution was heated at 25, 50, 90, 150, and 180 °C for 4 hours. Samples were taken for analysis, and the effective acid concentration released was calculated relative to the hydrochloric acid equivalent. The experimental results are as follows: Figure 3 The results show that the solid acid of the present invention still has good acid-generating ability in water with low mineralization.

[0090] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a slow-release solid autogenous acid, characterized in that, The method includes the following steps: Step S1: Dissolve chloroacetic anhydride in ethyl acetate, then add chloroacetic anhydride to the tertiary amine according to the molar ratio n. 氯乙酸酐 :n 叔胺 The tertiary amine is slowly added dropwise at a ratio of 1:2.0 to 2.2 and mixed thoroughly. Step S2: Heat the mixed solution from step S1 to the reaction temperature, reflux it thoroughly, and then remove ethyl acetate by rotary evaporation. Step S3: Soak the product obtained in step S2 in acetone solution, wash the product, and vacuum dry to constant weight to finally obtain a slow-release solid autogenous acid; the tertiary amine is selected from one of dodecyl dimethyl tertiary amine, hexadecyl dimethyl tertiary amine, octadecyl dimethyl tertiary amine or tetradecyl dimethyl tertiary amine; The structural formula of the slow-release solid autogenous acid is: ,in, R1 = dodecyl, tetradecyl, hexadecyl, or octadecyl.

2. The method for preparing a slow-release solid autogenous acid according to claim 1, characterized in that, The molar ratio of chloroacetic anhydride to tertiary amine is 1:2.0, 1:2.1, or 1:2.

2.

3. The method for preparing a slow-release solid autogenous acid according to claim 1, characterized in that, The reflux reaction conditions include: a reaction temperature of 70–80°C and a reaction time of 12–15 h.

4. The method for preparing a slow-release solid autogenous acid according to claim 1, characterized in that, The vacuum drying conditions include: a temperature of 40–50°C and a time of 8–10 hours.

5. A slow-release solid autogenous acid, characterized in that, It is prepared by the method described in any one of claims 1-4.

6. An application of the slow-release solid autogenous acid as described in claim 5, characterized in that, The application is for preparing a slow-release, self-generating acid solution.

7. The application of a slow-release solid autogenous acid according to claim 6 in acidification, characterized in that, The slow-release self-generating acid solution contains 5% to 30% by mass of slow-release solid self-generating acid, with the remainder being deionized water.

Images