A foam-displacing agent sustained-release capsule, a preparation method and application thereof

Abstract

The application discloses a foam displacement agent sustained-release capsule and a preparation method and application thereof. The foam displacement agent sustained-release capsule comprises a sustained-release film and a foam displacement agent coated in the sustained-release film; and the sustained-release film is a polymer film. The foam displacement agent sustained-release capsule has a sustained-release time of greater than 2 days under the gas well conditions of a temperature of 100-160 DEG C and a pH of 3-6, and the foamability, foam stability and liquid carrying capacity of a solution reach a peak value when the sustained-release time is 2-4 days, at which time, the liquid carrying capacity is greater than or equal to 120 mL, the foamability is greater than or equal to 140 mm, and the foam stability is greater than or equal to 120 mm. The foam displacement agent sustained-release capsule has good foamability, foam stability and liquid carrying capacity.

Description

Technical Field

[0001] This invention relates to the field of foam drainage and gas extraction technology, specifically to a foam drainage agent sustained-release capsule, its preparation method, and its application. Background Technology

[0002] With the intensification of gas field exploitation, fluid production has become a key issue restricting the normal production of gas wells. Foam drainage gas production is a rapidly developing drainage gas production technology both domestically and internationally in recent years. It has advantages such as simple equipment, convenient construction, low cost, wide applicability to well depths, and no impact on normal gas well production. Foam drainage involves injecting a foaming agent into the well through the annulus of the tubing or casing. Under the agitation of the gas flow, foam with a certain degree of stability is generated. The liquid phase that has slid and deposited in the tubing is transformed into foam, changing the relative density of the fluid in the lower part of the tubing. The continuously produced gas phase displaces the foam and flows out of the wellbore, thereby removing the accumulated fluid in the well and achieving the purpose of drainage gas production.

[0003] However, conventional foaming agents dissolve rapidly in water at the bottom of the well, quickly forming foam that is all carried out, resulting in a short-lasting foaming effect. This necessitates periodic addition of foaming agent based on the volume of fluid produced. In gas wells without a packer between the tubing and casing, the foaming agent is often injected into the casing in liquid form, which is convenient. However, in gas wells with a packer between the tubing and casing, foaming agent needs to be added to the tubing, often requiring a shut-in and then reopening operation. Frequent and periodic well opening and closing for adding foaming agent significantly impacts production and increases operational risks, especially in gas wells containing high levels of hydrogen sulfide, increasing labor costs and operational risks.

[0004] Currently, slow-release foaming agents are also gradually being researched. Slow-release technology slows down and prolongs the release rate of active agents, thus maintaining an effective concentration of active substances in the system for a longer period. Slow-release technology was initially and most widely used in the pharmaceutical field, and in oilfields, it is more commonly used for scale inhibition. Patent US20180134939A1 cross-links scale inhibitors and corrosion inhibitors onto a carrier through chemical bonds, for example, using the reaction of alcohols, amines, and acids. Downhole, the cross-linking bonds hydrolyze, slowly releasing the active substances. Shanghai University and other institutions have studied polyacryl alcohol hydrosol slow-release corrosion inhibitors and scale inhibitors. Changqing Oilfield has developed a slow-release foaming agent, which is produced by pressing a foaming agent with an inert solid material. The foaming agent gradually dissolves through the skeleton material, resulting in slow release, extending the dissolution time from the usual 9.5 hours to 51 hours. China National Petroleum Corporation's patent CN110003875A provides a slow-release liquid- and sand-carrying foaming agent and its preparation method, which mixes a surfactant foaming agent with 5-20% of casing as a slow-release agent, allowing the action time to reach 120 hours (5 days). However, the above are all applications below 90°C, which cannot be adapted to high-temperature applications, and animal materials also have problems such as a storage period of less than 3 months and batch-to-batch quality inconsistencies.

[0005] Therefore, there is a need for a long-lasting, slow-release foam drainage agent suitable for high-temperature, acidic gas wells. Summary of the Invention

[0006] To address the problems in the prior art, this invention provides a sustained-release capsule for a foaming agent, its preparation method, and its application. The sustained-release capsule of this invention, under conditions of 100-160℃ and pH = 3-6, can achieve a sustained-release time of more than 2 days. The foaming power, foam stabilization power, and liquid carrying capacity of the solution reach their peak after 2-4 days of sustained release. At this point, the liquid carrying capacity is ≥120mL, the foaming power is ≥140mm, and the foam stabilization power is ≥120mm. This effectively solves the problems of the prior art and can be used in the process of draining and producing gas from high-temperature acidic gas wells.

[0007] One of the objectives of this invention is to provide a sustained-release capsule for bubbling and detoxification.

[0008] The sustained-release capsule for the bubbling agent comprises a sustained-release membrane and a bubbling agent encapsulated therein; the sustained-release membrane is a polymer membrane.

[0009] In a preferred embodiment of the present invention,

[0010] The sustained-release membrane is a single-layer polymer membrane or a multi-layer polymer membrane, preferably a multi-layer polymer membrane.

[0011] In a preferred embodiment of the present invention,

[0012] The multilayer polymer membrane can be filled with a hydrophobic phase material between its layers; the hydrophobic phase material is preferably at least one of air, nitrogen, inert gas, paraffin wax, and polyethylene wax. The addition of the hydrophobic phase can prevent the aqueous solution from permeating into the inner membrane, further prolonging the sustained-release time. The thickness of the added hydrophobic material is 1–5 mm, meaning the space between the inner and outer polymer membranes is 1–5 mm.

[0013] In a preferred embodiment of the present invention,

[0014] The polymer membrane can be degraded or dissolved under pH control, and is preferably at least one of nylon membrane and polyester membrane, more preferably polyester membrane.

[0015] In a preferred embodiment of the present invention,

[0016] The polyester film is at least one of polybutylene terephthalate (PBT) film, polyethylene terephthalate (PET) film, polybutylene succinate (PBS) film, polybutylene succinate / terephthalate (PBST) film, and polybutylene adipate / terephthalate (PBAT) film.

[0017] In a preferred embodiment of the present invention,

[0018] The polymer film includes polymer films with and / or without heat shrinkability, preferably polymer films with heat shrinkability, and more preferably heat-shrinkable polyethylene terephthalate films.

[0019] In a preferred embodiment of the present invention,

[0020] The thickness of the single layer of the sustained-release membrane is 10 to 100 micrometers, preferably 20 to 80 micrometers.

[0021] In a preferred embodiment of the present invention,

[0022] The foaming agent is at least one of anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants;

[0023] The anionic surfactant is preferably at least one selected from α-olefin sulfonate, alkylbenzene sulfonate, alkyl sulfonate, alkyl polyether sulfate, and alkyl polyether carboxylate, more preferably at least one selected from sodium α-olefin sulfonate (AOS) and sodium alkyl polyether sulfate (AES); and / or,

[0024] The cationic surfactant is preferably at least one of alkylammonium chloride and alkylammonium bromide, more preferably dodecylammonium chloride; and / or,

[0025] The nonionic surfactant is preferably at least one of alkyl polyoxyethylene ether, amine oxide, and alkyl glycoside, more preferably alkyl polyoxyethylene ether; and / or

[0026] The zwitterionic surfactant is preferably at least one of alkylamide betaine and alkyl betaine, more preferably at least one of cocamidopropyl betaine and dodecyl betaine.

[0027] The slow-release capsule for the foaming agent described in this invention has a cross-sectional diameter smaller than the diameter of the well tubing in order to be well applied to gas well drainage and gas production. Preferably, it is one-half to two-thirds of the diameter of the well tubing. In actual gas well drainage and gas production operation environment, the diameter of the slow-release capsule for the foaming agent is more preferably 35-52 mm. In order to avoid bridging and accumulation in the well, the length of the slow-release capsule for the foaming agent is preferably greater than or equal to its diameter and less than or equal to 600 mm.

[0028] The membrane thickness of the sustained-release capsule for the foaming agent described in this invention is on the micrometer level. Therefore, it can be assumed that the size of the foaming agent inside the sustained-release capsule is equal to or slightly smaller than that of the capsule.

[0029] A second objective of this invention is to provide a method for preparing a sustained-release capsule for bubbling and detoxification, which is one of the objectives of this invention.

[0030] The method includes:

[0031] The foaming and draining agent is coated with a sustained-release film and sealed to obtain the sustained-release capsule of the foaming and draining agent.

[0032] In a preferred embodiment of the present invention,

[0033] The coating can be done using conventional coating processes in the prior art. In this invention, it is preferred to make the sustained-release film into a sleeve with one end open, then fill the foaming agent into the sustained-release film sleeve and seal it to obtain the foaming agent sustained-release capsule.

[0034] The sleeve can be prepared using conventional manufacturing processes in the prior art. In this invention, a blown film method is preferred, which includes the steps of melting, extruding, and inflating the polymer. More preferably, it includes: feeding the polymer into the feed hopper of an extruder, plasticizing and melting it under the dual action of heating the extruder barrel and shearing the screw, and then extruding the material melt into the die at a certain pressure and speed through the rotation of the screw and inflating it into a film bubble of a certain size. The film is then fed into a winding machine through cooling by an air ring and stretching by traction to complete the continuous manufacturing process of the sleeve.

[0035] In a preferred embodiment of the present invention,

[0036] The size of the sustained-release membrane after the sleeve is sealed is the size of the sustained-release capsule for the foaming agent.

[0037] In a preferred embodiment of the present invention,

[0038] When the foaming agent is in solid form, it is preferable to compress the foaming agent into a shape, then put the compressed foaming agent into a sustained-release film sleeve and seal it to obtain the foaming agent sustained-release capsule.

[0039] In a preferred embodiment of the present invention,

[0040] The pressing pressure is 10-30 MPa, and the pressing time is 0.5-15 min.

[0041] In a preferred embodiment of the present invention,

[0042] The compressed foaming agent is cylindrical. To avoid bridging and accumulation inside the wellbore, the cross-sectional diameter of the cylindrical foaming agent is preferably 2-5 mm smaller than the diameter of the sleeve.

[0043] In a preferred embodiment of the present invention,

[0044] After the compressed foaming agent is loaded into the slow-release membrane sleeve, the air in the sleeve is expelled before sealing.

[0045] The sealing can employ conventional sealing processes found in existing technologies. In this invention, preferred sealing processes include knotting, binding with inorganic degradable materials, adhesive bonding, and heat sealing. Heat sealing is preferred for sealing the slow-release film sleeve; more preferably, the sleeve end near the foaming agent is heated to 50–90°C to shrink and adhere tightly to the foaming agent before sealing.

[0046] Other commonly used additives in the art, such as inorganic salts, urea, and corrosion inhibitors, can also be added to the foaming agent of the present invention. The dosage is also the conventional dosage, and those skilled in the art can add them according to the actual situation.

[0047] A third objective of this invention is to provide an application of a foaming agent sustained-release capsule, which is one of the objectives of this invention, or a foaming agent sustained-release capsule prepared by the method of another objective of this invention, in foam drainage and gas production in acidic gas wells.

[0048] Specific applications include inserting at least one of the foaming agent slow-release capsules described in this invention into the tubing of a gas well. Under the action of acidic gas in the gas well, the foam is slowly released and generates foam with a certain stability, thereby draining the accumulated liquid in the well and achieving the purpose of draining the liquid and producing gas. The foaming agent slow-release capsules of this invention can be the same or different.

[0049] This invention relies on the hydrolysis of ester or amide bonds in a slow-release membrane at high temperatures. Ester bonds hydrolyze into acids and alcohols, while amide bonds hydrolyze into acids and amines. This process breaks down the polymer chains, degrades the slow-release membrane, and releases the foaming agent coated within. Acidic gases such as CO2 and hydrogen sulfide produced from gas wells dissolve in water, making the aqueous solution acidic (pH 3-6). The higher the pressure, the lower the pH, providing favorable conditions for the hydrolysis of ester and amide bonds (under neutral conditions, the hydrolysis temperature of amide bonds is 180-200℃).

[0050] The present invention has the following beneficial effects:

[0051] This invention provides a foam drainage gas recovery technology that allows for slow release of a foaming agent under the influence of acidic gas in gas wells, enabling a single injection and a long effective period. The foaming agent of this invention, after being coated, effectively delays its dissolution time, thereby extending its effective period. The sustained-release capsules of this invention exhibit a sustained-release time of more than 2 days under gas well conditions of 100-160℃ and pH 3-6. According to the Sinopec enterprise standard QSH CG0135-2021 "Technical Requirements for Foaming Agents," the foaming performance of the sustained-release capsules of this invention reaches its peak value in terms of foaming power, foam stabilization power, and liquid carrying capacity after 2-4 days of sustained release. At this point, the liquid carrying capacity is ≥120mL, the foaming power is ≥140mm, and the foam stabilization power is ≥120mm, demonstrating excellent foaming, foam stabilization, and liquid carrying capacity. This achieves good technical results and effectively solves the problems of short onset time, multiple injections, wasted process costs, and high operational risks associated with existing foam drainage agents during gas well development. Detailed Implementation

[0052] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0053] All raw materials used in the examples are commercially available.

[0054] Example 1

[0055] 170g of sodium α-olefin sulfonate (China National Light Industry Chemical Co., Ltd. AOS92%), 30g of sodium dodecyl sulfonate (China National Pharmaceutical Group Co., Ltd.), 10g of dodecyl polyoxyethylene ether (Jiangsu Haian Chemical Co., Ltd. AEO-7), and 30g of solid cocamidocyanate (Evonik) were kneaded for 15 minutes until uniformly mixed. The mixture was then pressed for 10 minutes using a hydraulic press at a pressure of 20MPa. Finally, the mixture was extruded at a speed of 30cm / min into foaming rods with a diameter of 5cm and a length of 10.5cm.

[0056] Take 50g of the compressed foam release stick (the diameter of the 50g foam release stick is still 5cm) and put it into a PET sleeve with a film thickness of 30μm and a sleeve diameter of 5.2cm. Keep one end open and put the other end containing the foam release stick into 70℃ hot water and let it stand for 10s. The PET bag will shrink. Take it out. At this time, the PET film and the foam release stick are stuck together. Tie it tightly to seal and form foam release agent sustained release capsule F1-A.

[0057] Take 50g of the compressed foam release stick (the cross-sectional diameter of the 50g foam release stick is still 5cm) and put it into a PBAT sleeve with a film thickness of 30μm and a sleeve diameter of 5.2cm. Keep one end open, expel the air from the bag from the bottom to the top, tie a knot to seal, and form a foam release agent sustained-release capsule F1-B.

[0058] Take 50g of the above-mentioned compressed foam release stick (the cross-sectional diameter of the 50g foam release stick is still 5cm) and put it into a nylon 66 sleeve with a film thickness of 30μm and a sleeve diameter of 5.2cm. Keep one end open, expel the air in the bag from the bottom to the top, tie a knot to seal, and form a foam release agent sustained-release capsule F1-C.

[0059] According to the QSH CG0135-2021 standard "Technical Requirements for Foaming Agents", 500g of saline solution with a mineralization of 50000mg / L was prepared. The saline solution was saturated with CO2 at 1MPa, and the pH was measured to be 4.5. Sealed sustained-release capsules F1-A, F1-B, and F1-C were added to the above saline solution and aged in ovens at 100℃ and 130℃ respectively. Every 24 hours, 500g of liquid was removed, and then 500g of fresh water saturated with CO2 and a mineralization of 50000mg / L was added. This process was repeated for four consecutive days. The removed solution was diluted 5 times with the corresponding mineralized water to 2500g. Referring to the QSH CG0135-2021 standard "Technical Requirements for Foaming Agents", the foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules were measured. The results are shown in Table 1 (100℃ aging) and Table 2 (130℃ aging).

[0060] Table 1. Foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules of the foaming agent in Example 1 after aging at 100°C.

[0061]

[0062]

[0063] Table 2 shows the foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules of the foaming agent in Example 1 after aging at 130°C.

[0064]

[0065] Example 2

[0066] The foam release sticks were pressed using the same method as in Example 1. 50g of the pressed foam release sticks (the cross-sectional diameter of the 50g foam release sticks was still 5cm) were placed into a PET sleeve with a film thickness of 30μm and a sleeve diameter of 5.2cm, leaving one end open. The other end containing the foam release sticks was placed in 70℃ hot water for 10 seconds, causing the PET bag to shrink. The bag was then removed, and the PET film adhered to the foam release sticks. The bag was then sealed tightly. Another PET sleeve of the same thickness was then placed over the outer layer of this sleeve. 10g of liquid paraffin was added between the two layers (forming a thickness of approximately 1mm). The same heat-shrinking method was used to form the foam release agent sustained-release capsule F2-A.

[0067] Using the above method, a PET sleeve with a three-layer film thickness of 30μm is used, and 10g of liquid paraffin is added between each layer to form a foaming agent sustained-release capsule F2-B.

[0068] Take 50g of the compressed foam release stick (the diameter of the 50g foam release stick is still 5cm) and put it into two PET sleeves with a film thickness of 30μm and a sleeve diameter of 5.2cm, which are stacked together. Keep one end open and put the other end containing the foam release stick into 70℃ hot water for 10 seconds. The PET bag will shrink. Take it out. At this time, the two layers of PET film and the foam release stick are stuck together. Tie the seal tightly to form the foam release agent sustained release capsule F2-C.

[0069] Take 50g of the compressed foam release stick (the cross-sectional diameter of the 50g foam release stick is still 5cm) and put it into a PET sleeve with a film thickness of 60μm and a sleeve diameter of 5.2cm. Keep one end open and put the other end containing the foam release stick into 70℃ hot water and let it stand for 10s. The PET bag will shrink. Take it out. At this time, the PET film and the foam release stick are stuck together. Tie it tightly to seal and form the foam release agent sustained release capsule F2-D.

[0070] Prepare 500g of saline solution with a mineralization of 50000mg / L according to the QSH CG0135-2021 "Technical Requirements for Foaming Agents" standard. Saturate the saline solution with 1MPa CO2 and determine the pH to be 4.5. Add sealed sustained-release capsules F2-A, F2-B, F2-C, and F2-D to the above saline solution and age them in ovens at 130℃ and 160℃ respectively. Take out 500g of liquid every 24 hours, and then add 500g of fresh water saturated with CO2 and a mineralization of 50000mg / L, for four consecutive days. Dilute the taken-out solution 5 times with the corresponding mineralized water to 2500g. According to the QSH CG0135-2021 "Technical Requirements for Foaming Agents" standard, determine the foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules. The results are shown in Table 3 (aging at 130℃) and Table 4 (aging at 160℃).

[0071] Table 3 shows the foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules of the foaming agent in Example 2 after aging at 130°C.

[0072]

[0073]

[0074] Table 4 shows the foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules of the foaming agent in Example 2 after aging at 160°C.

[0075]

[0076] The results show that the thickness of the polymer membrane has little effect on the sustained-release performance, and that increasing the number of membrane layers, especially when there are hydrophobic substances separating the membranes, can prolong the sustained-release performance.

[0077] Example 3

[0078] 50g of octadecyl polyoxyethylene ether (Hai'an A18E5), 60g of dodecyl ammonium chloride, 20g of sodium alkyl polyether sulfate (Jintong, AES-70) and 100g of solid cocamidopropyl betaine (Evonik) were mixed in a kneader for 15 minutes until homogeneous. The mixture was then pressed in a hydraulic press for 10 minutes at a pressure of 10MPa. Finally, it was extruded at a speed of 30cm / min into a bubble bar with a diameter of 5cm and a length of 10cm.

[0079] Take 50g of the compressed foam release stick (the cross-sectional diameter of the 50g foam release stick is still 5cm) and put it into a PBS sleeve with a membrane thickness of 50μm and a sleeve diameter of 5.2cm. Keep one end open, expel the air from the bag from the bottom to the top, and seal it tightly to form foam release agent sustained release capsule F3-A.

[0080] Take 50g of the compressed foam release stick (the cross-sectional diameter of the 50g foam release stick is still 5cm) and put it into a PBT sleeve with a film thickness of 50μm and a sleeve diameter of 5.2cm. Keep one end open, expel the air from the bag from the bottom to the top, tie a knot to seal, and form a foam release agent sustained-release capsule F3-B.

[0081] Take 50g of the compressed foam release stick (the cross-sectional diameter of the 50g foam release stick is still 5cm) and put it into a PBST sleeve with a membrane thickness of 50μm and a sleeve diameter of 5.2cm. Keep one end open, expel the air in the bag from the bottom to the top, tie a knot to seal, and form a foam release agent sustained-release capsule F3-C.

[0082] Prepare 500g of saline solution with a mineralization of 150,000 mg / L according to the QSH CG0135-2021 "Technical Requirements for Foaming and Detoxifying Agents" standard. Adjust the pH of the saline solution to 3 with acetic acid. Seal the sustained-release capsules F3-A, F3-B, and F3-C of the foaming and detoxifying agent, respectively, and add them to the above saline solution. Place them in an oven at 115℃ for aging. Every 24 hours, take out 500g of liquid and then add 500g of fresh water with a pH of 3 and a mineralization of 150,000 mg / L. Repeat this process for four consecutive days. Dilute the extracted solution 5 times with the appropriate amount of mineralized water to 2500g. Refer to the QSH CG0135-2021 "Technical Requirements for Foaming and Detoxifying Agents" standard to determine the foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules. The results are shown in Table 5.

[0083] Table 5 shows the foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules of the foaming agent in Example 3 after aging at 115°C.

[0084]

[0085] Example 4

[0086] The foaming rod was pressed using the same method as in Example 1 to prepare sustained-release capsules F1-A for the foaming agent.

[0087] Prepare 500g of saline solution with a mineralization of 50000mg / L according to the QSH CG0135-2021 "Technical Requirements for Foaming and Detoxifying Agents" standard. Adjust the pH of the saline solution to 6 with acetic acid. Add the sealed foaming and detoxifying agent sustained-release capsules F1-A to the above saline solution and age them in a 130℃ oven. Take out 500g of liquid every 24 hours, and then add 500g of fresh water with a pH of 6 and a mineralization of 50000mg / L, for four consecutive days. Dilute the taken-out solution 5 times with the corresponding mineralized water to 2500g. According to the QSH CG0135-2021 "Technical Requirements for Foaming and Detoxifying Agents" standard, determine the foaming power, foam stability, and liquid carrying capacity of the foaming and detoxifying agent sustained-release capsules. The results are shown in Table 6.

[0088] Table 6 shows the foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules of the foaming agent in Example 4 after aging at 130°C.

[0089]

[0090] Comparative Example 1

[0091] Take 50g of the same compressed foaming agent as in Examples 1, 3, and 4 (the diameter of the 50g foaming rod taken out is still 5cm). Without adding a slow-release membrane, prepare solutions using the saline solution from Examples 1, 3, and 4, respectively, according to the methods in the corresponding examples. Place the solutions in a 130℃ oven for aging. Take out 500g of the solution every 24 hours, and then add 500g of fresh saline solution, for four consecutive days. Dilute the taken-out solutions 5 times with the corresponding mineralized water to 2500g. According to the QSH CG0135-2021 "Technical Requirements for Foaming Agents" standard, determine the foaming power, foam stabilizing power, and liquid carrying capacity of the foaming agent. The results are shown in Table 7.

[0092] Table 7 shows the foaming properties of the foaming agents in the comparative examples after aging at 130℃.

[0093]

[0094] As can be seen from the examples and comparative examples, the sustained-release capsules of the foaming agent of the present invention have a sustained-release time of more than 2 days under gas well conditions of 100-160℃ and pH 3-6. According to the QSH CG0135-2021 standard "Technical Requirements for Foaming Agents", the foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules were measured. The foaming power, foam stability, and liquid carrying capacity of the sustained-release capsules of the present invention reach their peak values ​​after 2-4 days of sustained release. At this time, the liquid carrying capacity is ≥120mL, the foaming power is ≥140mm, and the foam stability is ≥120mm. It exhibits excellent foaming performance, foam stability, and liquid carrying capacity.

Claims

1. A sustained-release capsule for a foaming agent, comprising a sustained-release membrane and a foaming agent encapsulated therein; The sustained-release membrane is a polymer membrane; the polymer membrane is at least one of nylon membrane and polyester membrane; The polyester film is at least one of polybutylene terephthalate film, polyethylene terephthalate film, polybutylene succinate film, polybutylene succinate / butylene terephthalate film, and polyadipate / butylene terephthalate film. The foaming agent is at least one of anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants; The anionic surfactant is at least one of α-olefin sulfonate, alkylbenzene sulfonate, alkyl sulfonate, alkyl polyether sulfate, and alkyl polyether carboxylate. The cationic surfactant is at least one of alkyl ammonium chloride and alkyl ammonium bromide; The nonionic surfactant is at least one of alkyl polyoxyethylene ether, amine oxide, and alkyl glycoside; the zwitterionic surfactant is at least one of alkyl amide betaine and alkyl betaine.

2. The sustained-release capsule for detoxification as described in claim 1, characterized in that: The sustained-release membrane is a single-layer polymer membrane or a multi-layer polymer membrane.

3. The sustained-release capsule for detoxification as described in claim 2, characterized in that: The multilayer polymer film is filled with a hydrophobic phase substance between the layers; the hydrophobic phase substance is at least one of air, nitrogen, inert gas, paraffin wax, and polyethylene wax.

4. The sustained-release capsule for detoxification as described in claim 1, characterized in that: The polymer film includes polymer films that have and / or do not have heat shrinkage properties.

5. The sustained-release capsule for detoxification as described in claim 4, characterized in that: The polymer film is a polymer film with heat shrinkage properties.

6. The sustained-release capsule for detoxification as described in claim 5, characterized in that: The polymer film is a heat-shrinkable polyethylene terephthalate film.

7. The sustained-release capsule for detoxification as described in any one of claims 1-6, characterized in that: The thickness of the single layer of the sustained-release membrane is 10 to 100 micrometers.

8. The sustained-release capsule for detoxification as described in claim 7, characterized in that: The thickness of the sustained-release membrane is 20–80 micrometers.

9. A method for preparing a sustained-release capsule for detoxification as described in any one of claims 1-8, comprising: The foaming and draining agent is coated with a sustained-release film and sealed to obtain the sustained-release capsule of the foaming and draining agent.

10. The preparation method according to claim 9, characterized in that: The sustained-release membrane is made into a sleeve with one end open, and then the foaming agent is put into the sustained-release membrane sleeve and sealed to obtain the foaming agent sustained-release capsule.

11. The preparation method according to claim 10, characterized in that: When the foaming agent is in solid form, it is pressed into shape, and then the pressed foaming agent is put into a sustained-release film sleeve and sealed to obtain the foaming agent sustained-release capsule.

12. The application of a foaming agent sustained-release capsule as described in any one of claims 1-8 or a foaming agent sustained-release capsule prepared by the method described in any one of claims 9-11 in foam drainage gas production in acidic gas wells.

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