Preparation method of 220℃ controlled-release microcapsule acid for acid pressing

Abstract

The present invention discloses a method for preparing 220°C controlled-release microcapsule acid for acid fusing, comprising the following steps: S1, dissolving a multifunctional shell material, a polymerization promoter, a photoinitiator, and an emulsifier A into each other to form an oil phase, then pouring an acid solution into the oil phase to form an oil-water mixture, and stirring at high speed to form a W / O type colostrum; S2, adding an emulsifier B to the W / O type colostrum, then mixing and stirring the colostrum with an external aqueous phase solution to form a W / O / W type double emulsion; S3, irradiating the W / O / W type double emulsion with ultraviolet light under stirring to initiate photopolymerization until a granular product is formed; and filtering and drying to obtain a 220°C controlled-release microcapsule acid. The preparation method of the present invention is simple to operate, and the ultraviolet curing time is less than 10 minutes. The prepared microcapsule acid has strong pressure resistance and can avoid premature destruction and release in the wellbore caused by pumping shock; when it is pumped to the deep reservoir and reaches the response temperature, the shell of the microcapsule acid is destroyed and a large amount of acid is released, thereby achieving controlled release.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field acid fracturing, in particular to a method for preparing 220°C controlled-release microcapsule acid for acid fracturing. Background Art

[0002] In recent years, the development of carbonate oil and gas reservoirs in my country has been moving towards deep and ultra-deep reservoirs, and acid fracturing technology has also been facing challenges such as ultra-high temperature and ultra-high pressure. In particular, the performance of the acid system is facing severe challenges. The existing high-temperature retarded acid systems (such as thickening acid, cross-linked acid, etc.) mainly slow down the rate of hydrogen ion transfer to the rock wall by thickening, extend the length of acid-etched cracks, and thus improve the acid fracturing construction effect. However, in some deep and ultra-deep carbonate oil and gas reservoirs, the reservoir temperature has exceeded 220°C, and the viscosity of the existing retarded acid system has dropped sharply, making it difficult to meet the acid fracturing process requirements of deep and ultra-deep reservoirs. Microencapsulated acid technology is a new acid system that is expected to solve the above problems. The acid is encapsulated with specific polymer materials to form microcapsules. If the microcapsules can be kept below 220°C, the acid release rate will be extremely slow or even nonexistent. Above 220°C, the microcapsule shells deform, releasing a large amount of acid. This releases hydrogen ions at the distal end of the fracture, effectively extending the length of the acid-etched fractures and meeting the requirements of acid fracturing in deep and ultra-deep carbonate reservoirs. However, compared to liquid acid systems, solid microencapsulated acid faces another challenge: during acid fracturing, the microencapsulated acid will be squeezed and collide with the pipe wall, causing deformation or wall rupture, leading to premature release of the acid. Therefore, the encapsulated acid needs to have strong pressure resistance to withstand the impact of pumping and avoid premature release of the internal acid due to external damage before reaching the reservoir. However, research on the pressure resistance of microcapsules has been scarce.

[0003] Furthermore, currently available methods for preparing microencapsulated acid often involve complex and time-consuming processes such as emulsion polymerization and solution polymerization, significantly increasing the production time and cost of microencapsulated acid. Therefore, simplifying the preparation process for microencapsulated acid is also a technical challenge. Summary of the Invention

[0004] In view of the above problems existing in the existing microcapsule acid for acid pressing, the present invention provides a method for preparing 220°C controlled-release microcapsule acid for acid pressing.

[0005] The present invention provides a method for preparing 220°C controlled-release microcapsule acid for acid compression, comprising the following steps:

[0006] S1. Dissolve the multifunctional shell material, polymerization promoter, photoinitiator, and emulsifier A to form an oil phase. Then, pour the acid solution as the internal aqueous phase into the oil phase to form an oil-water mixture. Use a high-speed blender to stir at 1000-4000 rpm for 10-15 minutes to form a W / O colostrum.

[0007] The multifunctional shell material is selected from any one of trifunctional phenolic epoxy acrylate (PNEA-3), trifunctional polyurethane modified epoxy acrylate (PUEA-3), and hexafunctional polyurethane acrylate (PUA-6).

[0008] The polymerization promoter is selected from any one of neopentyl glycol diacrylate (NPGDA), ethylene phthalate glycol diacrylate (PDDA), 1,6-hexanediol dimethacrylate (HDODA) and dipropylene glycol diacrylate (DPGDA).

[0009] The acid solution is selected from any one of hydrochloric acid, earth acid, formic acid, acetic acid and hydrofluoric acid, and the volume concentration of the acid solution is 10%-40%.

[0010] S2. Add emulsifier B to the W / O colostrum, then mix the colostrum with the external aqueous phase solution, and stir at 300-800 rpm for 10-15 minutes to form a W / O / W type multiple emulsion; the external aqueous phase solution is a polyvinyl alcohol solution or a polyacrylamide solution with a mass percentage concentration of 2%.

[0011] S3. Irradiate the W / O / W type emulsion with ultraviolet light under stirring to initiate photopolymerization, and irradiate for 6-10 minutes until a granular product is formed; filter, wash the product, and dry it to obtain 220° C. controlled-release microcapsule acid.

[0012] Taking the total mass percentage of all raw materials as 100%, the mass percentage of each raw material in the total mass of all raw materials is as follows: the mass percentage of multifunctional shell material is 2.5%-15%, the mass percentage of polymerization promoter is 12%-24%, the mass percentage of photoinitiator is 0.8%-1.4%, the mass percentage of emulsifier A is 0.7%-2.8%, the mass percentage of acid solution is 15%-30%, the mass percentage of emulsifier B is 2.4%-4.8%, and the mass percentage of external aqueous phase solution is 35%-65%.

[0013] Preferably, the photoinitiator is 1-hydroxycyclohexyl phenyl ketone or 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0014] Preferably, the emulsifier A is selected from at least one of PEG-30 dipolyhydroxystearate, glyceryl stearate, and polyoxyethylene stearate.

[0015] Preferably, the emulsifier B is selected from any one of a composite emulsifier formed by mixing Span 80 and Tween 80 in a mass ratio of 4:6, sodium lauryl sulfonate, and sodium lauryl sulfate.

[0016] Preferably, in step S3, the W / O / W type emulsion is irradiated with ultraviolet light of 25-100 W under stirring at a speed of 300-800 rpm.

[0017] Compared with the prior art, the present invention is beneficial in that:

[0018] (1) The shell of the 220°C controlled-release microcapsule acid provided by the present invention is polymerized from shell materials with functionalities of 3 to 6. During the preparation process, the molecular chains of the shell materials with multiple functional groups undergo complex cross-linking. As a result, the prepared microcapsules have a dense and smooth shell that can withstand high temperatures of 220°C and exhibit significant pressure resistance. This pressure resistance prevents premature destruction and release of the microcapsule acid in the wellbore caused by pumping shock.

[0019] (2) The dense shell formed by the 220°C controlled-release microcapsule acid provided by the present invention can effectively encapsulate liquid acid. At temperatures below 220°C, the microcapsule shell can effectively prevent the internal acid from being released into the external solution, significantly reducing the rate of hydrogen ion transfer to the rock surface, thereby reducing the acid-rock reaction in the near-wellbore area. However, at temperatures above 220°C, the microcapsules have been transported to the deep reservoir, the shell material is destroyed by the high temperature, and the acid is released in large quantities and reacts with the rock at deep depths to form acid-etched cracks. Therefore, the microcapsule acid of the present invention can effectively solve the problem of insufficient acid-etched crack length caused by the rapid acid reaction in ultra-high temperature carbonate reservoirs.

[0020] (3) The method for preparing the 220°C controlled-release microencapsulated acid provided by the present invention is simple to operate and rapid to prepare. The polymerization reaction time required for the microencapsulated acid shell material ranges from 6 to 10 minutes. Furthermore, the prepared microencapsulated acid is a granular solid that is essentially non-released at room temperature, facilitating transportation and storage during construction.

[0021] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a flow chart of the preparation method of the 220°C controlled-release microcapsule acid of the present invention.

[0023] Figure 2 is the cumulative release rate of hydrogen ions of the microcapsule acid in Example 1 at different temperatures.

[0024] Figure 3The scanning electron microscope images are of the overall appearance and surface morphology of the microcapsules of Example 1 before acid release and the overall appearance after release at 220°C.

[0025] Figure 4 It is the cumulative release rate of hydrogen ions of the microcapsule acids of Examples 1-3 and Comparative Examples 1-3 at 220°C.

[0026] Figure 5 The crushing rates of the microcapsule acids of Examples 1-3 and Comparative Examples 1-3 under different pressures are shown. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0028] The preparation method of the acid-pressing controlled-release microcapsule acid at 220°C of the present invention is as follows: Figure 1 Specific preparation examples are as follows:

[0029] In all the following examples, the mass percentage of each raw material is the percentage of the mass of the raw material to the total mass of all raw materials, and the total mass of all raw materials is calculated as 100%.

[0030] Example 1

[0031] A method for preparing 220°C controlled-release microcapsule acid, comprising the following steps:

[0032] S1: 4 wt% PNEA-3, 15 wt% DPGDA, 1 wt% 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 1.5 wt% glycerol stearate are dissolved in each other to form an oil phase, and then 18 wt% of acid solution is poured into the oil phase to form an oil-water mixture. A high-speed stirrer is used to stir at a speed of 2000 rpm for 10 minutes to form a W / O type colostrum, wherein the acid solution is a 20 wt% hydrochloric acid solution.

[0033] S2: 2.5 wt% of emulsifier B was added to the colostrum, and the colostrum was mixed with 58 wt% of the external aqueous phase solution. The mixture was stirred at 800 rpm using a magnetic stirrer for 10 min to form a W / O / W type emulsion, wherein the composition of emulsifier B was Span80:Tween80=4:6, and the external aqueous phase solution was a 2 wt% polyvinyl alcohol solution.

[0034] S3: Under magnetic stirring at a speed of 800 rpm, an ultraviolet curing lamp was used to irradiate the emulsion at a light intensity of 75 W to initiate a photopolymerization reaction. After irradiation for 10 minutes, a hard granular product was formed. The product was filtered and washed three times with anhydrous ethanol and deionized water respectively, and then dried to obtain 220°C controlled-release microencapsulated acid.

[0035] The obtained 10g microcapsule acid was added to 20g distilled water, and the system was placed in a high temperature autoclave. The hydrogen ion release rate of the microcapsule acid at different temperatures was measured. The results are as follows: Figure 2 As shown. The results show that the microcapsule acid in Example 1 of the present invention is basically not released at 20°C, which can ensure its preservation during transportation and storage before acid fracturing construction. When the temperature is lower than 220°C, the hydrogen ions inside the microcapsule are released slowly and at a low rate, that is, when migrating in the wellbore, the shell of the microcapsule can effectively hinder the release of hydrogen ions. When the temperature reaches 220°C, the hydrogen ion release rate increases significantly, that is, when the microcapsule acid reaches the deep part of the crack, the shell of the microcapsule is destroyed, and a large amount of hydrogen ions are released and react with the reservoir rock, which can extend the length of the acid-etched crack.

[0036] The overall appearance and surface morphology of the microcapsule acid in Example 1 before release and after release at 220°C were observed using a scanning electron microscope. The results are as follows: Figure 3 As shown in the figure, (a) is a microscopic image before release, and (b) is a microscopic image after release. The results show that before release, the microcapsules are extremely spherical and have good encapsulation. Upon magnification, it is revealed that the microcapsule shell is extremely dense and has no porous channels, which can effectively hinder the release of hydrogen ions. However, after 5 hours of continuous release at 220°C, the dual effects of high temperature and external liquid pressure cause the microcapsule shell to deform inward, squeezing and releasing the acid liquid encapsulated within.

[0037] Example 2

[0038] A method for preparing 220°C controlled-release microcapsule acid, comprising the following steps:

[0039] S1: 4wt% PUA-6, 15wt% NPGDA, 1wt% 1-hydroxycyclohexyl phenyl ketone, and 1.5wt% PEG-30 dipolyhydroxystearate are dissolved in each other to form an oil phase, and then 18wt% acid solution is poured into the oil phase to form an oil-water mixture, which is stirred at 2000rpm using a high-speed stirrer for 10 minutes to form a W / O type colostrum, wherein the acid solution is a 20wt% hydrochloric acid solution.

[0040] S2: 2.5 wt% emulsifier B was added to the colostrum, and the colostrum was mixed with 58 wt% of the external aqueous phase solution. The mixture was stirred at 500 rpm using a magnetic stirrer for 10 minutes to form a W / O / W type emulsion, wherein the composition of emulsifier B was Span80:Tween80=3:7, and the external aqueous phase solution was a 2 wt% polyacrylamide solution.

[0041] S3: Under magnetic stirring at a speed of 500 rpm, use an ultraviolet curing lamp with a light intensity of 100 W to irradiate the emulsion to initiate photopolymerization. After irradiation for 8 minutes, a hard granular product is formed; filter, wash the photopolymerized product with anhydrous ethanol and deionized water for 3 times respectively, and dry it to obtain 220℃ controlled-release microencapsulated acid.

[0042] Example 3

[0043] Taking the total mass of all raw materials as 100%, the following steps are provided to prepare high-temperature resistant capsule acid:

[0044] S1: 4wt% of PUEA-3, 15wt% of NPGDA, 1.5wt% of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 2wt% of stearic acid polyoxyethylene ether are dissolved in each other to form an oil phase, and then 20wt% of acid solution is poured into the oil phase to form an oil-water mixture, which is stirred at a speed of 2000rpm using a high-speed stirrer for 10 minutes to form W / O type colostrum, wherein the acid solution is a mixture of hydrochloric acid and hydrofluoric acid. Before mixing, the hydrochloric acid concentration is 20wt% and the hydrofluoric acid concentration is 8wt%; the mixing mass ratio of hydrochloric acid and hydrofluoric acid is 4:1.

[0045] S2: 2.5 wt% sodium dodecyl sulfate was added to the colostrum, and the colostrum was mixed with 48 wt% of an external aqueous phase solution, and stirred at 500 rpm for 10 min using a magnetic stirrer to form a W / O / W type emulsion, wherein the external aqueous phase solution was a 2 wt% polyacrylamide solution.

[0046] S3: Under magnetic stirring at a speed of 500 rpm, use an ultraviolet curing lamp to irradiate the emulsion at a light intensity of 100 W to initiate photopolymerization. After irradiation for 6 minutes, a hard granular product is formed; filter, wash the photopolymerized product with anhydrous ethanol and deionized water three times respectively, and dry it at 220°C to obtain a controlled-release microcapsule acid.

[0047] Comparative Example 1

[0048] Based on Example 1, the trifunctional novolac epoxy acrylate (PNEA-3) in step S1 was replaced with the same amount of difunctional novolac epoxy acrylate (PNEA-2), and other conditions remained unchanged to prepare a microcapsule acid.

[0049] Comparative Example 2

[0050] On the basis of Example 2, the hexafunctional polyurethane acrylate (PUA-6) in step S1 was replaced with the same amount of trifunctional polyurethane acrylate (PUA-3), and other conditions remained unchanged to prepare a microcapsule acid.

[0051] Comparative Example 3

[0052] On the basis of Example 3, the trifunctional polyurethane-modified epoxy acrylate (PUEA-3) in step S1 was replaced with the same amount of trifunctional polyester acrylate (PEA-3), and other conditions remained unchanged to prepare a microcapsule acid.

[0053] Comparative Example 4

[0054] A method for preparing microencapsulated acid:

[0055] S1: 4wt% polyethylene glycol acrylate (PEGA-3), 15wt% DPGDA, 1wt% 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 1.5wt% P135 are dissolved in each other to form an oil phase, and then 18wt% acid solution is poured into the oil phase to form an oil-water mixture, which is stirred at 2000rpm for 10min using a high-speed stirrer to form a W / O type colostrum, wherein the acid solution is a 20wt% hydrochloric acid solution.

[0056] S2: 2.5 wt% emulsifier B was added to the colostrum, and the colostrum was mixed with 58 wt% of the external aqueous phase solution. The mixture was stirred at 800 rpm using a magnetic stirrer for 10 min to form a W / O / W type emulsion, wherein the composition of emulsifier B was Span80:Tween80=4:6, and the external aqueous phase solution was a 2 wt% polyvinyl alcohol solution.

[0057] S3: Under magnetic stirring at a speed of 800 rpm, the emulsion was irradiated with an ultraviolet curing lamp at a light intensity of 80 W to initiate photopolymerization. After irradiation for 10 minutes, a granular product was formed; the product was filtered, washed with anhydrous ethanol and deionized water three times, and dried to obtain microencapsulated acid.

[0058] Comparative Example 4 replaces PNEA-3 with polyethylene glycol acrylate (PEGA-3) based on Example 1, and other preparation conditions remain unchanged. It was found that the product prepared with polyethylene glycol acrylate (PEGA-3) had low sphericity, a porous shell, extremely low strength, and could be crushed by fingers. This will cause the acid to be completely released in the wellbore because the shell material is easily destroyed by external forces, which will not only aggravate wellbore corrosion, but also cause waste of acid that should have reacted with reservoir rocks. This phenomenon occurs because polyethylene glycol acrylate (PEGA-3) has poor acid resistance and will hydrolyze in a strong acid environment, affecting the polymerization of the shell material, thereby preparing a product with unqualified performance. This also shows that not all trifunctional shell materials or multifunctional shell materials are suitable for preparing the microcapsule acid of the present invention.

[0059] The two key application properties of the microcapsule acid products prepared in Examples 1-3 and Comparative Examples 1-3 were evaluated in terms of controlled release performance and compressive resistance. The evaluation methods and results are described below.

[0060] (1) Controlled release performance evaluation

[0061] Test of the cumulative release rate of microencapsulated acid at 220°C: 10g of microencapsulated acid was placed in a high-temperature and high-pressure reactor containing 20g of distilled water, and the hydrogen ion release rate of the microencapsulated acid at 220°C was measured.

[0062] The test results are as follows Figure 4 As shown, the release rate of the microencapsulated acids in Examples 1-3 increased dramatically after being heated to 220°C. Their shells, severely deformed by the high temperature and external liquid pressure, released a large amount of the encapsulated acid liquid, achieving controlled release at 220°C. The cumulative release rates reached 90.25%, 89.52%, and 85.58%, respectively. These results demonstrate that these three microencapsulated acids can be released in large quantities in the reservoir at 220°C and react with the rock, effectively extending the length of acid-etched fractures and potentially improving the acid fracturing effect in deep reservoirs.

[0063] In contrast, in Comparative Example 1, which has a functionality of only 2 (PNEA-2), the shell material undergoes severe deformation during the heating process (at a temperature of approximately 110°C) due to the temperature and external liquid pressure. Consequently, the release rate is much higher than in the other examples from the outset. This results in the microencapsulated acid being released in large quantities in the wellbore, exacerbating acid corrosion on the wellbore and prematurely consuming the acid that would otherwise react with the reservoir rock, resulting in a poor acid fracturing effect. Comparative Example 2 uses a trifunctional polyurethane acrylate as the shell material. Experimental results show that this microencapsulated acid suffers from similar poor temperature resistance as the microencapsulated acid in Comparative Example 1. However, using a hexafunctional polyurethane acrylate as the shell material allows the preparation of microencapsulated acids that meet the requirements of the present invention. This demonstrates that not all trifunctional shell materials are suitable for the microencapsulated acids of the present invention. The microencapsulated acid prepared in Comparative Example 3 showed no burst release after being heated to 220°C. Instead, the release rate increased due to accelerated molecular diffusion caused by the increased temperature, indicating that the release behavior was still due to diffusion. Furthermore, the final release rate was only 32.95%. This low release rate not only resulted in waste of acid but also made it difficult to react adequately with the reservoir rock, resulting in minimal improvement in the acid fracturing effect. This further demonstrates that not all trifunctional shell materials are suitable for the microencapsulated acid of this invention.

[0064] (2) Compressive performance evaluation

[0065] Test of the acid crushing rate of microcapsules under different pressure conditions: With reference to the proppant compression test standard, the microcapsules obtained in Examples 1-3 and Comparative Examples 1-3 were vibrated and sieved with a 500-mesh sieve (the average particle size of the microcapsules is 30 μm, i.e., 500 mesh). The microcapsules that did not pass through the 500-mesh sieve were selected and subjected to a compression test using a proppant crushing device. 4 g of the screened microcapsules were taken respectively, and pressure was applied to the microcapsules at 7 MPa, 14 MPa, 21 MPa, 28 MPa, and 35 MPa in the proppant crusher and the pressure was maintained for 180 seconds. After the pressure was applied, the microcapsules after pressure were vibrated and sieved again with a 500-mesh sieve, and the mass of the microcapsules passing through the sieve was weighed. The crushing rate of the microcapsules was the mass of the microcapsules passing through the sieve after pressure was applied divided by the initial mass of 4 g.

[0066] The test results are as follows Figure 5 As shown, the breakage rate of each microcapsule acid increases with increasing pressure. Under a high pressure of 35 MPa, the breakage rates of the microcapsule acids in Comparative Examples 1 and 2 reached 35.2% and 37.6%, respectively. The breakage rates of the products in Examples 1-3 and Comparative Example 3 were all below 20%. Although the breakage rate of Comparative Example 3 was lower, its acid release performance at 220°C did not meet the performance requirements of the present invention.

[0067] A comprehensive consideration of acid release and compression resistance reveals that only the microcapsule acids prepared in Examples 1-3 meet the performance requirements of the present invention. Specifically, only trifunctional novolac epoxy acrylate (PNEA-3), trifunctional polyurethane-modified epoxy acrylate (PUEA-3), and hexafunctional polyurethane acrylate (PUA-6) as shell materials can produce microcapsules with controlled release at 220°C for acid compression.

[0068] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, 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 technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing 220°C controlled-release microcapsule acid for acid compression, characterized in that: The following steps are involved: S1. Dissolve the multifunctional shell material, polymerization promoter, photoinitiator, and emulsifier A in each other to form an oil phase, then pour the acid solution as the inner aqueous phase into the oil phase to form an oil-water mixture, and stir the mixture at 1000-4000 rpm for 10-15 minutes using a high-speed stirrer to form a W / O colostrum. The multifunctional shell material is selected from any one of trifunctional phenolic epoxy acrylate, trifunctional polyurethane modified epoxy acrylate, and hexafunctional polyurethane acrylate; The polymerization promoter is selected from any one of neopentyl glycol diacrylate, ethylene phthalate diacrylate, 1,6-hexanediol dimethacrylate and dipropylene glycol diacrylate; The acid solution is selected from any one of hydrochloric acid, earth acid, formic acid, acetic acid, and hydrofluoric acid; The emulsifier A is selected from at least one of PEG-30 dipolyhydroxystearate, glyceryl stearate, and polyoxyethylene stearate; S2. Add emulsifier B to the W / O colostrum, then mix the colostrum with the external aqueous phase solution, and stir at 300-800 rpm for 10-15 minutes to form a W / O / W double emulsion; The external aqueous phase solution is a polyvinyl alcohol solution or a polyacrylamide solution with a mass percentage concentration of 2%; The emulsifier B is selected from any one of a composite emulsifier of Span 80 and Tween 80, sodium lauryl sulfonate, and sodium lauryl sulfate; Span 80 and Tween 80 are compounded in a mass ratio of 4:6 or 3:7 to form a composite emulsifier; S3. Irradiating the W / O / W emulsion with ultraviolet light under stirring to initiate photopolymerization for 6-10 minutes until a granular product is formed; The product was filtered, washed, and dried to obtain 220°C controlled-release microcapsule acid.

2. The method for preparing 220°C controlled-release microcapsule acid for acid compression according to claim 1, characterized in that: Taking the total mass percentage of all raw materials as 100%, the mass percentage of multifunctional shell material accounts for 2.5%-15%, the mass percentage of polymerization promoter accounts for 12%-24%, the mass percentage of photoinitiator accounts for 0.8%-1.4%, the mass percentage of emulsifier A accounts for 0.7%-2.8%, the mass percentage of acid solution accounts for 15%-30%, the mass percentage of emulsifier B accounts for 2.4%-4.8%, and the mass percentage of external aqueous phase solution accounts for 35%-65%.

3. The method for preparing 220°C controlled-release microcapsule acid for acid compression according to claim 1, characterized in that: The mass concentration of the acid solution is 10%-40%.

4. The method for preparing 220°C controlled-release microcapsule acid for acid compression according to claim 1, characterized in that: The photoinitiator is 1-hydroxycyclohexyl phenyl ketone or 2-hydroxy-2-methyl-1-phenyl-1-propanone.

5. The method for preparing 220°C controlled-release microcapsule acid for acid compression according to claim 1, characterized in that: In step S3, the W / O / W type emulsion is irradiated with ultraviolet light of 25-100W intensity.

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