A controllable degradation temporary plugging material, its preparation method and application

Abstract

This invention discloses a degradable temporary plugging material, its preparation method, and its application. The temporary plugging material comprises a temporary plugging matrix and a hydrophobic layer coating the surface of the matrix. The hydrophobic layer is selected from a mixture of materials including hydrophobic materials and emulsifiers. In this invention, by coating the surface of the temporary plugging matrix with a hydrophobic material, the diffusion of water into the matrix within a certain temperature range is inhibited, achieving controllable degradation. Simultaneously, by dispersing an emulsifier in the hydrophobic material, the material is protected by polyethylene wax after degradation, thus promoting degradation.

Description

Technical Field

[0001] This invention belongs to the field of temporary plugging materials, and particularly relates to degradable temporary plugging materials. Specifically, it relates to a degradable temporary plugging material, its preparation method, and its application. Background Technology

[0002] Petroleum is an important component of current industrial energy supply, and a stable oil supply plays a vital role in economic and social development. In the process of oil development, fracturing has become an important method of formation modification in order to increase oil and gas production.

[0003] By injecting large amounts of fluid into the formation under high pressure, numerous fractures can be created, increasing oil and gas production channels and boosting yields. During fracturing, different formations are fracturing in stages. Bridge plugs are used to isolate the stages, and within each stage, temporary plugging balls or particles are used to temporarily plug the clusters that have fractured, forcing the fluid flow towards the next cluster to open, thus improving the fracturing effect.

[0004] In the above process, temporary plugging materials are required for the separation between fracturing segments and the sealing of priority opening clusters within segments. These temporary plugging materials are biodegradable in fracturing fluid. During fracturing, they act as a sealant, and after fracturing, they degrade on their own without affecting subsequent operations or requiring special treatment. This simplifies the construction process, reduces construction difficulty, and improves formation stimulation effectiveness.

[0005] Polyester products with ester groups in their main chain can be used as temporary plugging materials because they can be hydrolyzed and degraded in water. However, in order to ensure rapid degradation after underground construction, materials that degrade quickly are generally selected. This results in the material starting to degrade during the storage period and the early stages of construction, before it reaches the designated geological layer or before construction is completed, thus affecting the effectiveness of the temporary plugging. Summary of the Invention

[0006] To overcome the problems existing in the prior art, the present invention provides a degradable and controllable temporary plugging material, its preparation method and application, wherein a hydrophobic material (e.g., polyethylene wax) is coated on the surface of the temporary plugging substrate, thereby inhibiting the diffusion of water into the temporary plugging substrate within a certain temperature range, thus achieving the purpose of controllable degradation; at the same time, by dispersing an emulsifier in the hydrophobic material (e.g., polyethylene wax), the protection of polyethylene wax is removed after reaching the degradation environment, thus promoting the degradation of the material.

[0007] The first aspect of the present invention is to provide a degradation-controllable temporary plugging material, comprising a temporary plugging matrix and a hydrophobic layer wrapped around the surface of the temporary plugging matrix.

[0008] In the temporary plugging material of the present invention, the temporary plugging matrix is ​​selected from one or more of the following: polyglycolic acid, polylactide, polybutylene succinate, polycaprolactone, polybutylene terephthalate, polybutylene terephthalate, polybutylene succinate, polymethyl ethylene carbonate, and polyhydroxy fatty acid ester.

[0009] In the temporary plugging material of the present invention, the hydrophobic layer is selected from a mixture of materials including hydrophobic materials and emulsifiers.

[0010] In the temporary plugging material of the present invention, the emulsifier is 0.1-10 wt%, preferably 1-5 wt%, based on 100 wt% of the hydrophobic layer; and / or, the hydrophobic material is 90-99.9 wt%, preferably 95-99 wt%, based on 100 wt% of the hydrophobic layer.

[0011] In the temporary plugging material of the present invention, the hydrophobic material is selected from at least one of hydrophobic materials with a melting point between 80 and 135°C; preferably, the hydrophobic material is selected from at least one of hydrophobic materials with a melting point 3 to 8°C lower than the target formation temperature; more preferably, the hydrophobic material is selected from polyethylene wax.

[0012] In the temporary plugging material of the present invention, the emulsifier is selected from at least one of nonionic surfactants; preferably, the emulsifier is selected from at least one of sorbitan laurate, tetraethylene glycol monolaurate, polyether sorbitan monostearate, hexaethylene glycol monostearate, polyether lanolin ether, polyether sorbitan monooleate, polyether sorbitan tristearate, polyether sorbitan trioleate, polyether sorbitan monolaurate, nonylphenol polyether, polyether oleyl alcohol ether, polyether methyl glucoside sesquioleate, and polyether sorbitan monopalmitate, wherein the polyether is preferably polyoxyethylene ether, polyoxypropylene ether, or polyoxyethylene-propylene copolymer ether.

[0013] In the temporary plugging material of the present invention, the emulsifier is selected from sorbitan laurate, tetraethylene glycol monolaurate, polyoxyethylene (4EO) sorbitan monostearate, hexaethylene glycol monostearate, polyoxypropylene (5PO) lanolin ether, polyoxyethylene (5EO) sorbitan monooleate, polyoxyethylene (20EO) sorbitan tristearate, polyoxyethylene (20EO) sorbitan trioleate, polyoxyethylene (4EO) sorbitan monolaurate, and nonyl sorbitan monolaurate. At least one of the following: phenolic polyoxyethylene (10) ether, polyoxyethylene (20EO) sorbitan monostearate, polyoxyethylene (20EO) oleyl alcohol ether, polyoxyethylene (20EO) methyl glucoside sesquioleate, polyoxyethylene (16EO) lanolin alcohol ether, polyoxyethylene (25EO) lanolin alcohol ether, polyoxyethylene (20EO) sorbitan monooleate, polyoxyethylene (20EO) sorbitan monopalmitate, and polyoxyethylene (20EO) sorbitan monolaurate.

[0014] A second aspect of the present invention is to provide a method for preparing a degradable temporary plugging material, preferably used for preparing the aforementioned degradable temporary plugging material. The preparation method includes: mixing the emulsifier with the hydrophobic material in a molten state to obtain a hydrophobic layer mixture; adding a temporary plugging matrix to the hydrophobic layer mixture; impregnating and then removing the matrix; and cooling to obtain the degradable temporary plugging material.

[0015] In the preparation method described in this invention, the hydrophobic material is heated to at least 50°C above its melting point to obtain the hydrophobic material in a molten state.

[0016] In the preparation method described in this invention, the emulsifier is uniformly dispersed in the hydrophobic material in a molten state using a high-speed emulsifier to obtain the hydrophobic layer mixture.

[0017] In the preparation method described in this invention, the temporary plugging matrix is ​​added to the hydrophobic layer mixture, immersed for more than 5 seconds, and then removed. After the surface liquid has drained, the mixture is cooled to obtain the degradation-controllable temporary plugging material.

[0018] A third aspect of the present invention is to provide the application of the above-mentioned temporary plugging material in fracturing. Detailed Implementation

[0019] 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.

[0020] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0021] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0022] One of the objectives of this invention is to provide a degradation-controllable temporary plugging material, comprising a temporary plugging matrix and a hydrophobic layer wrapped around the surface of the temporary plugging matrix.

[0023] In a preferred embodiment, the temporary plugging matrix is ​​selected from biodegradable materials.

[0024] The temporary plugging matrix can be selected from any material known in the art that can be used as a temporary plugging agent.

[0025] In a further preferred embodiment, the temporary plugging matrix is ​​selected from one or more of the following: polyglycolic acid, polylactide, polybutylene succinate, polycaprolactone, polybutylene terephthalate, polybutylene terephthalate, polybutylene succinate, polymethyl ethylene carbonate, and polyhydroxyalkanoates.

[0026] In a further preferred embodiment, the melt flow index of the temporary plugging matrix is ​​above 1 g / 10 min.

[0027] In a preferred embodiment, the hydrophobic layer is selected from a mixture of materials including hydrophobic materials and emulsifiers.

[0028] The hydrophobic layer on the surface of the temporary plugging substrate can effectively prevent degradation caused by moisture such as humid air, extend the shelf life of the product, and simplify the product packaging, eliminating the need for vacuum or moisture-proof packaging. This solves the problem that existing temporary plugging materials begin to degrade due to humid air during storage after manufacturing.

[0029] This invention also solves the problem that existing temporary plugging materials, after being hydrophobically coated, cannot effectively degrade once they enter the formation. As mentioned earlier, simply wrapping the temporary plugging material with some hydrophobic material can delay degradation. However, since the degradation of biodegradable materials requires the participation of water, completely isolating moisture and preventing the material from contacting water after construction will prevent effective degradation. By compounding an emulsifier with an HLB value greater than 8 into the hydrophobic material (preferably polyethylene wax), the hydrophobic material (preferably polyethylene wax) can be dispersed by the emulsifier after melting at high temperatures, thereby destroying the hydrophobic layer and allowing the material to degrade smoothly.

[0030] Specifically, taking polyethylene wax as an example, after entering the target formation, the polyethylene wax melts and is then emulsified and dispersed by an emulsifier, peeling off from the biodegradable material matrix. After separation from the polyethylene wax, the degradation of the biodegradable material is not affected; the polyethylene wax itself does not degrade. However, after being dispersed in water by the emulsifier, the polyethylene wax is discharged.

[0031] In a further preferred embodiment, based on 100 wt% of the hydrophobic layer, the emulsifier is 0.1-10 wt%, preferably 1-5 wt%; and the hydrophobic material is 90-99.9 wt%, preferably 95-99 wt%.

[0032] For example, based on 100 wt% of the hydrophobic layer, the emulsifier is 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%; and the hydrophobic material is 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 99.5 wt%, or 99.9 wt%.

[0033] In a further preferred embodiment, the average thickness of the hydrophobic layer is 10-500 μm, for example, 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm.

[0034] In a preferred embodiment, the hydrophobic material is selected from at least one of hydrophobic materials with a melting point between 80 and 135°C (e.g., 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or 135°C).

[0035] In a further preferred embodiment, the hydrophobic material is selected from at least one of hydrophobic materials whose melting point is 3 to 8°C lower than the target formation temperature (e.g., 3°C, 4°C, 5°C, 6°C, 7°C or 8°C).

[0036] One of the technical problems this invention aims to solve is addressing the low adaptability of existing temporary plugging materials to different degradation temperatures in formations. This invention utilizes hydrophobic materials with different melting points (such as polyethylene wax), ensuring that the material can only effectively begin degradation after reaching the target formation and being in a specific temperature environment.

[0037] In a further preferred embodiment, the hydrophobic material is selected from polyethylene wax; preferably, the melting point of the polyethylene wax is 80-135°C, more preferably, the melting point of the polyethylene wax is 3-8°C lower than the target formation temperature.

[0038] For example, the melting point of the polyethylene wax is 80°C, 90°C, 100°C, 110°C, 120°C, 130°C or 135°C. More preferably, the melting point of the polyethylene wax is 3°C, 4°C, 5°C, 6°C, 7°C or 8°C lower than the temperature of the target formation.

[0039] In a preferred embodiment, the emulsifier is selected from at least one of nonionic surfactants; preferably, the emulsifier is selected from at least one of sorbitan laurate, tetraethylene glycol monolaurate, polyether sorbitan monostearate, hexaethylene glycol monostearate, polyether lanolin ether, polyether sorbitan monooleate, polyether sorbitan tristearate, polyether sorbitan trioleate, polyether sorbitan monolaurate, nonylphenol polyether, polyether oleyl alcohol ether, polyether methyl glucoside sesquioleate, and polyether sorbitan monopalmitate, wherein the polyether is preferably polyoxyethylene ether, polyoxypropylene ether, or polyoxyethylene-propylene copolymer ether.

[0040] In a further preferred embodiment, the emulsifier is selected from sorbitan laurate, tetraethylene glycol monolaurate, polyoxyethylene (4EO) sorbitan monostearate, hexaethylene glycol monostearate, polyoxypropylene (5PO) lanolin ether, polyoxyethylene (5EO) sorbitan monooleate, polyoxyethylene (20EO) sorbitan tristearate, polyoxyethylene (20EO) sorbitan trioleate, polyoxyethylene (4EO) sorbitan monolaurate, and nonyl sorbitan monolaurate. At least one of the following: phenolic polyoxyethylene (10) ether, polyoxyethylene (20EO) sorbitan monostearate, polyoxyethylene (20EO) oleyl alcohol ether, polyoxyethylene (20EO) methyl glucoside sesquioleate, polyoxyethylene (16EO) lanolin alcohol ether, polyoxyethylene (25EO) lanolin alcohol ether, polyoxyethylene (20EO) sorbitan monooleate, polyoxyethylene (20EO) sorbitan monopalmitate, and polyoxyethylene (20EO) sorbitan monolaurate.

[0041] In a further preferred embodiment, the emulsifier has an HLB value greater than 8.

[0042] In a further preferred embodiment, the emulsifier is in a dispersed state in the hydrophobic material (preferably polyethylene wax) and can be well dispersed.

[0043] This invention primarily addresses the problem that ordinary temporary plugging materials degrade prematurely due to water exposure before reaching the target formation during transportation, storage, and application, resulting in a loss of mechanical properties. It also improves the accuracy of the material's degradation response characteristics at different temperatures. By adding an emulsifier to hydrophobic materials with different melting points (such as polyethylene wax), a hydrophobic protective film is formed and adhered to the surface of the plugging substrate or component. This film inhibits moisture penetration, eliminating the need for moisture-proof packaging during storage and transportation. Furthermore, it allows for more precise initiation of degradation at different formation temperatures during construction, improving the controllability of the temporary plugging process.

[0044] A second objective of this invention is to provide a method for preparing a degradable and controllable temporary plugging material, preferably used to prepare the degradable and controllable temporary plugging material described in one objective of this invention. The preparation method includes: mixing the emulsifier with the hydrophobic material in a molten state to obtain a hydrophobic layer mixture; adding the temporary plugging matrix into the hydrophobic layer mixture; impregnating and then removing the matrix; and cooling to obtain the degradable and controllable temporary plugging material.

[0045] In a preferred embodiment, the hydrophobic material is heated to at least 50°C above its melting point to obtain the hydrophobic material in a molten state.

[0046] In a preferred embodiment, the hydrophobic layer mixture is obtained by uniformly dispersing the emulsifier in the molten hydrophobic material using a high-speed emulsifier.

[0047] In a preferred embodiment, the temporary plugging matrix is ​​added to the hydrophobic layer mixture, immersed for more than 5 seconds, and then removed. After the surface liquid has drained, the mixture is cooled to obtain the degradation-controllable temporary plugging material.

[0048] In a preferred embodiment, the temporary plugging matrix is ​​spherical, granular, or any other shape, such as a temporary plugging ball, temporary plugging particle, or other shaped component.

[0049] The target components of the temporary plugging matrix are manufactured through processes such as extrusion, injection molding, and machining. For example, temporary plugging balls are obtained by injection molding, temporary plugging particles are obtained by extrusion granulation, and other components such as bridge plugs are obtained by machining the extruded rods.

[0050] In the method described in this invention: (1) the biodegradable matrix is ​​made into the target part by extrusion, injection molding, machining and other processes; for example, temporary plugging balls are obtained by injection molding, temporary plugging particles are obtained by extrusion granulation, and other parts such as bridge plugs are obtained by machining the extruded rods; (2) the hydrophobic material (e.g., polyethylene wax) is heated to a temperature greater than 50°C above the melting point, the emulsifier is added to the hydrophobic material (e.g., polyethylene wax), and the emulsifier is uniformly dispersed in the hydrophobic material (e.g., polyethylene wax) at high temperature by a high-speed emulsifier; (3) the target part of the temporary plugging matrix is ​​immersed in the above dispersion liquid, taken out after more than 5 seconds, the surface hydrophobic material (e.g., polyethylene wax) liquid is drained, and the finished product is obtained by cooling.

[0051] The temporary plugging material obtained by the technical solution of this invention has a surface coated with a hydrophobic material (such as polyethylene wax), which can isolate the temporary plugging material from moisture during storage and the initial stage of construction. No moisture-proof or vacuum storage is required during the storage period. During the initial stage of construction, before reaching the designated geological stratum, the temporary plugging material will not come into contact with water and begin to degrade.

[0052] The temporary plugging material obtained by the technical solution of the present invention has a surface coating of hydrophobic material (such as polyethylene wax) with different melting points, which can be selected according to the temperature of the target formation. This allows the temporary plugging material to begin degrading only after it reaches the target formation and is in a specific temperature environment.

[0053] The temporary plugging material obtained by the technical solution of the present invention contains an emulsifier with an HLB value greater than 8 in the hydrophobic material (e.g., polyethylene wax) coated on the surface. When the material is in water at a temperature higher than the melting point of the hydrophobic material (e.g., polyethylene wax), the emulsifier will assist the dispersion of the hydrophobic material (e.g., polyethylene wax) in the water, thereby ensuring the contact between water and the temporary plugging material, so that the material will not degrade due to the coating of the hydrophobic layer.

[0054] Compared to untreated temporary plugging materials, the temporary plugging material obtained by the technical solution of this invention retains more than 98% of its strength after three months of open placement without sealing or vacuum packaging. The temporary plugging material obtained by this invention can be effectively degraded in water at a specific temperature (e.g., the temperature of the target formation). The temporary plugging material obtained by this invention will degrade normally in water at a specific ambient temperature and will not lose its degradation characteristics due to the technical solution.

[0055] A third objective of this invention is to provide the application of the temporary plugging material described in the first objective of this invention, or the temporary plugging material obtained by the preparation method described in the second objective of this invention, in fracturing.

[0056] The "at least one" or "multiple" as used in this invention includes one, two or more, three or more, four or more. The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, endpoint values ​​of various ranges, endpoint values ​​of 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 herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] (1) The surface of the temporary plugging material described in this invention is coated with a hydrophobic material (e.g., polyethylene wax), which can isolate the temporary plugging substrate from moisture during storage and the initial stage of construction, and does not require moisture protection or vacuum storage during the storage period.

[0059] (2) The temporary plugging material described in this invention will not degrade when it does not reach the target formation. When it reaches the target formation, the emulsifier will assist the hydrophobic material (e.g., polyethylene wax) in the dispersion in water, thereby ensuring the contact between water and the temporary plugging matrix, and the temporary plugging matrix will degrade.

[0060] [Examples and Comparative Examples]

[0061] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0062]

Example 1

[0063] A polyethylene glycol temporary plugging ball with a diameter of 15 mm was obtained;

[0064] Polyethylene wax with a melting point of 120°C is heated to a temperature 50°C or higher than the melting point. The emulsifier, dehydrated sorbitan laurate, is added to the polyethylene wax. The amount of emulsifier is 1.5 wt% based on a total weight of 100 wt% of emulsifier and polyethylene wax. The emulsifier is then uniformly dispersed in the polyethylene wax using a high-speed emulsifier at the system temperature to obtain a dispersion.

[0065] The polyethylene glycol temporary plugging balls were immersed in the above dispersion for more than 5 seconds, then removed, the polyethylene wax liquid on the surface was drained, and the mixture was cooled to obtain the finished product. The average thickness of the hydrophobic layer was 100 μm.

[0066]

Example 2

[0067] Obtain a polylactide temporary plugging ball with a diameter of 10 mm;

[0068] The polyethylene wax with a melting point of 95°C is heated to a temperature greater than 50°C. The emulsifier polyoxyethylene (20EO) dehydrated sorbitan monostearate is added to the polyethylene wax. The amount of emulsifier is 3wt% based on a total weight of 100wt% of emulsifier and polyethylene wax. The emulsifier is uniformly dispersed in the polyethylene wax using a high-speed emulsifier at the system temperature to obtain a dispersion.

[0069] The polylactide temporary plugging balls were immersed in the above dispersion for more than 5 seconds, then removed, the polyethylene wax liquid on the surface was drained, and the mixture was cooled to obtain the finished product. The average thickness of the hydrophobic layer was 100 μm.

[0070]

Example 3

[0071] Polyglycolic acid temporary plugging particles with a particle size of 100μm-200μm were obtained;

[0072] Polyethylene wax with a melting point of 110°C is heated to a temperature 50°C or higher than the melting point. Polyoxyethylene (20EO) dehydrated sorbitan monopalmitate emulsifier is added to the polyethylene wax. The amount of emulsifier is 4.5 wt% based on a total weight of 100 wt% of emulsifier and polyethylene wax. The emulsifier is uniformly dispersed in the polyethylene wax using a high-speed emulsifier at the system temperature to obtain a dispersion.

[0073] The polyethylene glycol temporary plugging particles were immersed in the above dispersion for more than 5 seconds, then removed, the polyethylene wax liquid on the surface was drained, and the mixture was cooled to obtain the finished product. The average thickness of the hydrophobic layer was 100 μm.

[0074]

Example 4

[0075] A polylactide temporary plugging ball with a diameter of 45 mm was obtained;

[0076] Polyethylene wax with a melting point of 100°C is heated to a temperature greater than 50°C. Nonylphenol polyoxyethylene (10) ether emulsifier is added to polyethylene wax. The amount of emulsifier is 5 wt% based on a total weight of 100 wt% of emulsifier and polyethylene wax. The emulsifier is uniformly dispersed in polyethylene wax using a high-speed emulsifier at the system temperature to obtain a dispersion.

[0077] The polylactide temporary plugging balls were immersed in the above dispersion for more than 5 seconds, then removed, the polyethylene wax liquid on the surface was drained, and the mixture was cooled to obtain the finished product. The average thickness of the hydrophobic layer was 100 μm.

[0078] Comparative Example 1

[0079] A polyethylene lactide temporary plugging ball with a diameter of 15 mm was obtained. Polyethylene wax with a melting point of 120°C was heated to a temperature 50°C or higher than the melting point to obtain a polyethylene wax liquid. The polyethylene lactide temporary plugging ball was immersed in the above polyethylene wax liquid for more than 5 seconds, then removed, the surface polyethylene wax liquid was drained, and the ball was cooled to obtain the finished product.

[0080] Comparative Example 2

[0081] A polylactide temporary plugging ball with a diameter of 10 mm was obtained.

[0082] Comparative Example 3

[0083] Polyglycolic acid temporary plugging particles with a diameter of 100μm-200μm were obtained;

[0084] Polyoxyethylene (20EO) dehydrated sorbitan monopalmitate is melted to form a molten liquid (this emulsifier is solid at room temperature, but can be used for impregnation after melting). The polyethylene glycol temporary plugging particles are immersed in the molten liquid for more than 5 seconds, then removed, drained of surface liquid, and cooled to obtain the finished product.

[0085]

Experiment Example 1

[0086] The samples obtained from the examples and the comparative examples were left open at room temperature without moisture protection or vacuum packaging. After three months, the strength retention rate was tested on a universal testing machine, as shown in Table 1.

[0087] Table 1. Long-term storage characteristics of temporary plugging materials in the examples and comparative examples.

[0088] Strength retention rate % Example 1 98.3 Example 2 99.1 Example 3 98.5 Example 4 98.1 Comparative Example 1 98 Comparative Example 2 78.5 Comparative Example 3 38.3

[0089] It can be seen that Examples 1-4 and Comparative Example 1, due to the protection of the polyethylene wax layer, are not affected by humid air when left open for a long time, and their strength retention rate is relatively high. In contrast, Comparative Examples 2 and 3, which do not have polyethylene wax protection, show a significant decrease in strength. The above data confirms that the product obtained by this technical solution can simplify storage and transportation methods and ensure stable performance during the storage period.

[0090]

Experiment Example 2

[0091] Since the temporary plugging material must be degraded under specific conditions (referring to the target formation) before final application, the temporary plugging material is kept in water for 24 hours at temperatures 5°C below and above the melting point of the corresponding polyethylene wax. When the temperature is above 98°C, the test is conducted in a high-pressure sealed container, and when the temperature is below 98°C, the test is conducted in a normal-pressure blue-capped reagent bottle.

[0092] The strength retention rate of the products was tested on a universal testing machine. The data are shown in Table 2.

[0093] Table 2. High-temperature degradation characteristics of the examples and comparative examples.

[0094]

[0095] As can be seen, the product obtained in the embodiments of the present invention can effectively maintain a high strength retention rate when the temperature is 5°C below the melting point of polyethylene wax, proving that polyethylene wax can effectively protect the temporarily plugging matrix, isolate it from water, and basically prevent degradation. However, when the temperature is 5°C above the melting point of polyethylene wax, the polyethylene wax melts, and the emulsifier helps the polyethylene wax disperse in water, releasing the isolation between the temporarily plugging matrix and water, thereby allowing the temporarily plugging matrix to fully degrade.

[0096] In contrast: In Comparative Example 1, because the polyethylene wax lacked an emulsifier, although it melted at temperatures 5°C above its melting point, it remained adsorbed on the surface of the temporary plugging material, preventing moisture absorption and thus hindering complete degradation. In Comparative Example 2, due to the absence of polyethylene wax protection, degradation was faster at both temperatures. In Comparative Example 3, although an emulsifier was present, the lack of polyethylene wax prevented effective moisture isolation, resulting in relatively rapid degradation.

[0097] The above data proves that the product obtained by this invention only begins to degrade in water at a specific temperature. Furthermore, once the designated temperature is reached, the polyethylene wax layer disperses and is discharged with the formation water, while any residue is dissolved and discharged upon contact with crude oil. This does not affect subsequent degradation characteristics. Products not treated with this technical solution lack this temperature response characteristic and will begin to degrade regardless of long-term storage or before the temporary plugging material reaches the designated formation temperature environment. This is detrimental to the product's effectiveness at the target location, further demonstrating the superiority of this invention.

[0098] Note: Since both Example 3 and Comparative Example 3 are in the form of fine powder, their strength cannot be directly measured. Therefore, in actual measurement, the powders before and after aging were melted and injection molded into spheres with a size of 15 mm, and tested in the same way as in Example 1.

[0099] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A degradable temporary plugging material comprising a temporary plugging matrix and a hydrophobic layer coating the surface of the temporary plugging matrix, wherein the hydrophobic layer is selected from a mixture of materials including a hydrophobic material and an emulsifier, wherein the hydrophobic material is polyethylene wax, and the emulsifier is selected from at least one nonionic surfactant, wherein the emulsifier has an HLB value greater than 8.

2. The temporary plugging material according to claim 1, characterized in that, The temporary plugging matrix is ​​selected from one or more of the following: polyglycolic acid, polylactide, polybutylene succinate, polycaprolactone, polybutylene terephthalate, polybutylene terephthalate, polybutylene succinate, polymethyl ethylene carbonate, and polyhydroxy fatty acid ester.

3. The temporary plugging material according to claim 1, characterized in that, The emulsifier is 0.1 to 10 wt% of 100 wt% of the hydrophobic layer; and / or the hydrophobic material is 90 to 99.9 wt% of 100 wt% of the hydrophobic layer.

4. The temporary plugging material according to claim 1, characterized in that, The emulsifier is 1-5 wt% of 100 wt% of the hydrophobic layer; and / or, the hydrophobic material is 95-99 wt% of 100 wt% of the hydrophobic layer.

5. The temporary plugging material according to claim 1, characterized in that, The emulsifier is selected from at least one of the following: sorbitan laurate, tetraethylene glycol monolaurate, polyether sorbitan monostearate, hexaethylene glycol monostearate, polyether lanolin ether, polyether sorbitan monooleate, polyether sorbitan tristearate, polyether sorbitan trioleate, polyether sorbitan monolaurate, nonylphenol polyether, polyether oleyl alcohol ether, polyether methyl glucoside sesquioleate, and polyether sorbitan monopalmitate.

6. The temporary plugging material according to claim 5, characterized in that, The polyether is a polyoxyethylene ether, a polyoxypropylene ether, or a polyoxyethylene-propylene copolyether.

7. The temporary plugging material according to claim 5, characterized in that, The emulsifier is selected from at least one of the following: sorbitan laurate, tetraethylene glycol monolaurate, polyoxyethylene sorbitan monostearate, hexaethylene glycol monostearate, polyoxypropylene lanolin ether, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan monolaurate, nonylphenol polyoxyethylene ether, polyoxyethylene sorbitan monostearate, polyoxyethylene oleyl alcohol ether, polyoxyethylene methyl glucoside sesquioleate, polyoxyethylene lanolin ether, polyoxyethylene lanolin ether, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene sorbitan monolaurate.

8. A method for preparing a degradable temporary plugging material, used to prepare the degradable temporary plugging material according to any one of claims 1 to 7, the preparation method comprising: The emulsifier is mixed with the hydrophobic material in a molten state to obtain a hydrophobic layer mixture. The temporary plugging matrix is ​​added to the hydrophobic layer mixture, impregnated, and then removed and cooled to obtain the degradation-controllable temporary plugging material.

9. The preparation method according to claim 8, characterized in that, The hydrophobic material is heated to at least 50°C above its melting point to obtain the hydrophobic material in a molten state.

10. The preparation method according to claim 8, characterized in that, The hydrophobic layer mixture is obtained by uniformly dispersing the emulsifier in the molten hydrophobic material using a high-speed emulsifier.

11. The preparation method according to any one of claims 8 to 10, characterized in that, The temporary plugging matrix is ​​added to the hydrophobic layer mixture, immersed for more than 5 seconds, and then removed. After the surface liquid has drained, it is cooled to obtain the degradation-controllable temporary plugging material.

12. The application of the temporary plugging material according to any one of claims 1 to 7 or the temporary plugging material obtained by the preparation method according to any one of claims 8 to 11 in fracturing.

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