A fracturing proppant with a hydrophobic aerogel coating for achieving slow settling and a method of making the same

Abstract

This invention discloses a fracturing proppant with a hydrophobic aerogel coating that achieves slow settling, its preparation method, and its application, relating to the field of oil and gas well enhancement technology. A hydrophobic silica aerogel is prepared by introducing methyl-rich trimethylmethoxysilane. Before curing, the gel liquid is sprayed onto the proppant surface using fluidized bed spraying. After post-treatment, a hydrophobically modified aerogel is formed on the proppant surface. Due to the special papillary structure formed by the hydrophobic silica aerogel on the proppant surface, a lotus leaf effect is generated, thus forming a gas film. This gas film and its porous structure ultimately form a fracturing proppant that can be freely suspended in water, achieving slow settling through a hydrophobic aerogel coating. The proppant coated with the gas film and aerogel can be freely suspended in water, exhibiting excellent suspension and stability, reducing the requirements for fluid viscoelasticity, eliminating the need for large amounts of organic thickeners, reducing damage to the reservoir, and the preparation process is simple, low-cost, and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas well production enhancement technology, specifically relating to a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling and its preparation method. Background Technology

[0002] Hydraulic fracturing is a key measure to enhance oil and gas field productivity, achieving significant results in the field. This technology utilizes surface pump units to inject high-pressure fluid into the well to create fractures, while simultaneously injecting proppant-containing fluid to fill the fractures. After well shut-in and flowback, the fractures close, but the proppant remains within them, preventing further closure and forming a stable, highly efficient flow channel to enhance production. Effective proppant suspension is crucial in fracturing; excessively rapid settling can prevent proppant from entering the fractures, affecting effective support.

[0003] Currently, the proppants used in fracturing technology mainly include quartz sand, ceramsite, and their modified products. Traditional fracturing fluids require increased viscosity to ensure the suspension performance of the proppant. However, high-viscosity proppant-carrying fluids can cause formation damage and blockage. Therefore, low-viscosity slickwater fracturing technology has become a highly efficient and economical development approach. To maintain good suspension characteristics of proppants in low-viscosity fluids, proppant modification currently focuses on two main aspects. One is reducing the relative density of the proppant to improve suspension, such as low-density and ultra-low-density proppants. However, these proppants are complex to prepare, costly, have low compressive strength, and are easily broken. The second is to coat the proppant surface with a chemical coating, such as coating the proppant surface with a swelling polymer. The coating absorbs water and expands during use, thereby suspending the proppant. However, these coatings are prone to deformation, have unstable bonding with the proppant, and may even cause blockage of pores and throats within the fracture.

[0004] Existing low-density and ultra-low-density proppants suffer from complex preparation, high cost, low compressive strength, and fragility. Furthermore, proppants with surface chemical coatings are prone to deformation and unstable bonding with the proppant, potentially causing blockage of pores and throats within fractures. Therefore, a new technology is urgently needed to improve the suspension properties of proppants and solve this pressing problem in the field of oil and gas well enhancement. This new technology needs to overcome the problems of traditional proppants, maintaining suspension performance in low-viscosity liquids, thereby improving proppant efficiency in hydraulic fracturing and providing a more feasible solution for increasing production capacity. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating and its preparation method, so as to solve the technical problems of existing low-density and ultra-low-density proppants, such as complex preparation, high cost, low compressive strength and easy breakage, and proppants with surface chemical coatings are prone to deformation, unstable bonding with proppant, and may even cause blockage of pores and throats in the fracture.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a method for preparing a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating, comprising the following steps:

[0008] S1: Trimethylmethoxysilane, organosilane coupling agent, methyltriethoxysilane and organic solvent are stirred and mixed evenly. An acidic substance is added to adjust the pH value to 2-3. After complete hydrolysis, silica hydrosol is obtained. Then an alkaline substance is added to adjust the pH value to 7-8. The mixture is stirred and mixed evenly to form a gel solution.

[0009] S2: The proppant and the gel solution obtained in step S1 are mixed and fluidized sprayed. After curing, a gel is formed. After post-treatment, a silica aerogel is formed, and a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating is obtained.

[0010] Preferably, in step S1, the molar ratio of trimethylmethoxysilane:organosilane coupling agent:methyltriethoxysilane:organic solvent is (0.2-0.5):1:3:5; and the hydrolysis temperature is 45-55℃.

[0011] Preferably, in step S1, the organosilane coupling agent is any one of tetraethyl orthosilicate, methyl orthosilicate, tetraethyl orthosilicate, and butyl orthosilicate; the organic solvent is any one of isopropanol, methanol, ethanol, cyclohexane, n-hexane, and ethyl acetate.

[0012] Preferably, in step S1, the acidic substance is any one of hydrochloric acid, nitric acid, and oxalic acid; the alkaline substance is any one of ammonia, sodium carbonate, and sodium bicarbonate.

[0013] Preferably, in step S2, the mass ratio of the gel solution to the support is (5-15):100.

[0014] Preferably, in step S2, the temperature of fluidized spraying is 45-50℃ and the flow rate is 1.0-1.2m / s.

[0015] Preferably, in step S2, the post-treatment includes aging at 45-50°C for 48-60 hours and drying at 75-80°C for 12-14 hours.

[0016] Preferably, in step S2, the proppant is either 40-120 mesh quartz sand or ceramsite.

[0017] The present invention also discloses a fracturing proppant prepared by the above preparation method that utilizes a hydrophobic aerogel coating to achieve slow settling, comprising an inner core proppant particle, an outer aerogel coating layer in the middle, and an outermost gas film based on the lotus leaf effect.

[0018] The present invention also discloses the application of the above-mentioned fracturing proppant with hydrophobic aerogel coating for slow settling in hydraulic fracturing.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention discloses a method for preparing a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating. A hydrophobic silica aerogel is prepared by introducing methyl-rich trimethylmethoxysilane. Before curing, the gel liquid is uniformly sprayed onto the proppant surface using fluidized bed spraying. After post-treatment, a hydrophobically modified aerogel layer is formed on the proppant surface. Due to the special papillary structure formed by the hydrophobic silica aerogel on the proppant surface, a lotus leaf effect is generated, forming an air film. This air film, along with its unique porous structure, ultimately forms a fracturing proppant that can freely suspend in water, achieving slow settling using a hydrophobic aerogel coating. By coating the proppant surface with hydrophobic modified silica aerogel, the suspension performance of the proppant is effectively enhanced. On the one hand, because silica aerogel easily adheres to the proppant surface, and because silica aerogel has a porous structure, the density of the proppant coated with silica aerogel will be reduced. On the other hand, the hydrophobic modified silica aerogel sprayed onto the proppant surface forms a layer of micro-nano structured papillae. These hydrophobic protrusions on the silica aerogel surface will generate a lotus leaf effect, thereby forming a gas film. The resulting fracturing proppant with slow settling achieved by the hydrophobic aerogel coating has excellent suspension and stability. The proppant coated with gas film and aerogel can be freely suspended in water, reducing the requirements for fluid viscoelasticity. It can be applied to more fracturing scenarios and does not require the use of large amounts of organic thickeners, reducing damage to the reservoir. The preparation process is simple, low-cost, and environmentally friendly, which is of great significance for increasing oil and gas reservoir production.

[0021] The present invention also discloses a fracturing proppant prepared by the above preparation method that utilizes a hydrophobic aerogel coating to achieve slow settling, comprising core proppant particles, an outer aerogel coating layer, and an air film generated based on the lotus leaf effect. It has excellent suspension and stability, can be freely suspended in water, reduces the requirements for fluid viscoelasticity, can be applied to more fracturing scenarios, and does not require the use of a large amount of organic thickener, thus reducing damage to the reservoir.

[0022] This invention also discloses the application of the fracturing proppant with hydrophobic aerogel coating that achieves slow settling in hydraulic fracturing. The fracturing proppant with hydrophobic aerogel coating that achieves slow settling can be effectively suspended in the fracturing process, forming a stable and efficient flow channel in the fracture, thereby achieving increased production. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling, as disclosed in this invention.

[0024] Figure 2 This is a schematic diagram of the secondary structure of the outer hydrophobic silica aerogel disclosed in this invention.

[0025] Wherein: 1-Air film generated based on lotus leaf effect; 2-Core support particles; 3-Outer layer silica aerogel. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] The present invention will now be described in further detail with reference to the accompanying drawings:

[0029] The present invention discloses a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling, comprising core proppant particles, an outer aerogel coating layer, and an air film generated based on the lotus leaf effect.

[0030] The formation mechanism of the slow-settling fracturing proppant using a hydrophobic aerogel coating disclosed in this invention is as follows:

[0031] A hydrophobic silica aerogel was prepared by introducing methyl-rich trimethylmethoxysilane. During the preparation process, the gel liquid was uniformly sprayed onto the proppant surface using a fluidized bed before gelation. Subsequently, a hydrophobically modified aerogel layer was formed on the proppant surface. Due to the special porous structure, hydrophobicity, and special papillary structure formed on the proppant surface of the silica aerogel itself, a lotus leaf effect will be generated on the surface, thereby forming an air film. Finally, a fracturing proppant that can be freely suspended in low viscosity water or even clean water and achieves slow settling by utilizing the hydrophobic aerogel coating was formed.

[0032] This invention discloses a method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow-settling, comprising the following steps:

[0033] S1: Trimethylmethoxysilane, organosilane coupling agent, methyltriethoxysilane and organic solvent are stirred and mixed evenly. An acidic substance is added to adjust the pH of the solution to 2-3. The solution is fully hydrolyzed at 45-55℃ to obtain silica hydrosol. Then an alkaline substance is added to adjust the pH of the solution to 7-8. The solution is stirred and mixed evenly to form a gel solution.

[0034] S2: The gel solution and proppant are added into a fluidized bed and fluidized spraying is carried out under certain operating conditions. After curing, a gel is formed, and after post-treatment, a silica aerogel is formed, thus obtaining a fracturing proppant that achieves slow settling by utilizing a hydrophobic aerogel coating.

[0035] In step S1, the organosilane coupling agent includes one of tetraethyl orthosilicate, methyl orthosilicate, tetraethyl orthosilicate, and butyl orthosilicate.

[0036] The organic solvent is one of isopropanol, methanol, ethanol, cyclohexane, n-hexane, and ethyl acetate; the molar ratio of trimethylmethoxysilane: organosilane coupling agent: methyltriethoxysilane: organic solvent is (0.2-0.5):1:3:5;

[0037] The acidic substance is any one of hydrochloric acid, nitric acid, and oxalic acid;

[0038] The alkaline substance is any one of ammonia, sodium carbonate, and sodium bicarbonate.

[0039] In step S2, the fluidized bed operating temperature is 45-50℃, and the flow rate is controlled between 1.0-1.2m / s.

[0040] Post-processing includes aging and drying operations, with aging at 45-50℃ for 48-60 hours and drying at 75-80℃ for 12-14 hours.

[0041] The proppant is one of 40-120 mesh quartz sand or ceramsite; the mass ratio of gel solution to proppant is (5-15):100.

[0042] See Figure 1 This is a schematic diagram of the fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling, as disclosed in this invention. As can be seen from the figure, the fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes: an inner core proppant particle, an outer aerogel coating layer in the middle, and an outermost gas film based on the lotus leaf effect.

[0043] See Figure 2 This is a schematic diagram of the secondary structure of the outer hydrophobic silica aerogel disclosed in this invention. As can be seen from the figure, the silica aerogel in the outer aerogel coating layer exhibits a porous spatial structure, which is beneficial for encapsulating more gas in the gas film.

[0044] Example 1

[0045] A method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes the following steps:

[0046] 1) In a three-necked flask, add 0.02 mol trimethylmethoxysilane, 0.1 mol tetraethyl orthosilicate, 0.3 mol methyltriethoxysilane, and 0.5 mol isopropanol in sequence and stir until homogeneous. Then, add hydrochloric acid to the above mixed solution to adjust the pH value to 2, and hydrolyze it completely at 45°C to obtain silica hydrosol. Then, add ammonia water to the above silica hydrosol to adjust the pH value to 7, and stir for 2 minutes to form a gel solution.

[0047] 2) The above gel solution and 80-120 mesh quartz sand were added to a fluidized bed at a mass ratio of 5:100. Fluidized spraying was carried out at 45°C and a flow rate of 1.0 m / s. After curing, a gel was formed. The gel was then aged at 45°C for 48 h and dried at 75°C for 12 h to form silica aerogel, thus obtaining a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating.

[0048] Example 2

[0049] A method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes the following steps:

[0050] 1) In a three-necked flask, add 0.05 mol trimethylmethoxysilane, 0.1 mol tetraethyl orthosilicate, 0.3 mol methyltriethoxysilane, and 0.5 mol isopropanol in sequence and stir until homogeneous. Then, add hydrochloric acid to the above mixed solution to adjust the pH value to 3, and hydrolyze it completely at 55°C to obtain silica hydrosol. Then, add ammonia water to the above silica hydrosol to adjust the pH value to 8, and stir for 2 minutes to form a gel solution.

[0051] 2) The above gel solution and 80-120 mesh quartz sand were added to a fluidized bed at a mass ratio of 15:100. Fluidized spraying was carried out at 50°C and a flow rate of 1.2 m / s. After curing, a gel was formed. The gel was then aged at 50°C for 60 h and dried at 80°C for 14 h to form silica aerogel, thus obtaining a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating.

[0052] Example 3

[0053] A method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes the following steps:

[0054] 1) In a three-necked flask, add 0.04 mol trimethylmethoxysilane, 0.1 mol tetraethyl orthosilicate, 0.3 mol methyltriethoxysilane, and 0.5 mol isopropanol in sequence and stir until homogeneous. Then, add hydrochloric acid to the above mixed solution to adjust the pH value to 2, and hydrolyze it completely at 50°C to obtain silica hydrosol. Then, add ammonia water to the above silica hydrosol to adjust the pH value to 8, and stir for 2 minutes to form a gel solution.

[0055] 2) The above gel solution and 80-120 mesh quartz sand are added to a fluidized bed at a mass ratio of 10:100. Fluidized spraying is carried out at 50°C and a flow rate of 1.1 m / s. After curing, a gel is formed. The gel is then aged at 50°C for 54 h and dried at 80°C for 13 h to form silica aerogel, thus obtaining a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating.

[0056] Example 4

[0057] A method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes the following steps:

[0058] 1) In a three-necked flask, add 0.03 mol trimethylmethoxysilane, 0.1 mol tetraethyl orthosilicate, 0.3 mol methyltriethoxysilane, and 0.5 mol isopropanol in sequence and stir until homogeneous. Then, add hydrochloric acid to the above mixed solution to adjust the pH value to 2, and hydrolyze it completely at 50°C to obtain silica hydrosol. Then, add ammonia water to the above silica hydrosol to adjust the pH value to 8, and stir for 2 minutes to form a gel solution.

[0059] 2) The above gel solution and 80-120 mesh quartz sand were added to a fluidized bed at a mass ratio of 5:100. Fluidized spraying was carried out at 50°C and a flow rate of 1.0 m / s. After curing, a gel was formed. The gel was then aged at 50°C for 48 h and dried at 80°C for 12 h to form silica aerogel, thus obtaining a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating.

[0060] Example 5

[0061] A method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes the following steps:

[0062] 1) In a three-necked flask, add 0.03 mol trimethylmethoxysilane, 0.1 mol tetraethyl orthosilicate, 0.3 mol methyltriethoxysilane, and 0.5 mol isopropanol in sequence and stir until homogeneous. Then, add hydrochloric acid to the above mixed solution to adjust the pH value to 2, and hydrolyze it completely at 50°C to obtain silica hydrosol. Then, add ammonia water to the above silica hydrosol to adjust the pH value to 8, and stir for 2 minutes to form a gel solution.

[0063] 2) The above gel solution and 80-120 mesh quartz sand were added to a fluidized bed at a mass ratio of 15:100. Fluidized spraying was carried out at 50°C and a flow rate of 1.2 m / s. After curing, a gel was formed. The gel was then aged at 50°C for 48 h and dried at 80°C for 12 h to form silica aerogel, thus obtaining a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating.

[0064] Example 6

[0065] A method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes the following steps:

[0066] 1) In a three-necked flask, add 0.02 mol trimethylmethoxysilane, 0.1 mol methyl orthosilicate, 0.3 mol methyltriethoxysilane, and 0.5 mol methanol sequentially and stir until homogeneous. Then, add nitric acid to the above mixture to adjust the pH to 3, and hydrolyze it completely at 45°C to obtain silica hydrosol. Add sodium carbonate to the above silica hydrosol to adjust the pH to 7, and stir for 2 minutes to form a gel solution.

[0067] 2) The above gel solution and 80-120 mesh ceramsite were added to a fluidized bed at a mass ratio of 5:100. Fluidized spraying was carried out at 45°C and a flow rate of 1.0 m / s. After curing, a gel was formed. The gel was then aged at 45°C for 48 h and dried at 75°C for 12 h to form silica aerogel, thus obtaining a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating.

[0068] Example 7

[0069] A method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes the following steps:

[0070] 1) In a three-necked flask, add 0.05 mol trimethylmethoxysilane, 0.1 mol tetraethyl orthosilicate, 0.3 mol methyltriethoxysilane, and 0.5 mol ethanol in sequence and stir until homogeneous. Then, add oxalic acid to the above mixed solution to adjust the pH value to 3, and hydrolyze it completely at 55°C to obtain silica hydrosol. Then, add sodium bicarbonate to the above silica hydrosol to adjust the pH value to 8, and stir for 2 minutes to form a gel solution.

[0071] 2) The above gel solution and 80-120 mesh ceramsite were added to a fluidized bed at a mass ratio of 15:100. Fluidized spraying was carried out at 50°C and a flow rate of 1.2 m / s. After curing, a gel was formed. The gel was then aged at 55°C for 60 h and dried at 80°C for 14 h to form silica aerogel, thus obtaining a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating.

[0072] Example 8

[0073] A method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes the following steps:

[0074] 1) In a three-necked flask, add 0.03 mol trimethylmethoxysilane, 0.1 mol tetrabutyl orthosilicate, 0.3 mol methyltriethoxysilane, and 0.5 mol cyclohexane sequentially and stir until homogeneous. Then, add hydrochloric acid to the above mixture to adjust the pH to 2, and hydrolyze it completely at 50°C to obtain silica hydrosol. Add ammonia to the above silica hydrosol to adjust the pH to 8, and stir for 2 minutes to form a gel solution.

[0075] 2) The above gel solution and 80-120 mesh ceramsite were added to a fluidized bed at a mass ratio of 14:100. Fluidized spraying was carried out at 47°C and a flow rate of 1.2 m / s. After curing, a gel was formed. The gel was then aged at 47°C for 48 h and dried at 77°C for 12 h to form silica aerogel, thus obtaining a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating.

[0076] Example 9

[0077] A method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes the following steps:

[0078] 1) In a three-necked flask, add 0.02 mol trimethylmethoxysilane, 0.1 mol tetraethyl orthosilicate, 0.3 mol methyltriethoxysilane, and 0.5 mol n-hexane sequentially and stir until homogeneous. Then, add hydrochloric acid to the above mixture to adjust the pH to 3, and hydrolyze it completely at 50°C to obtain silica hydrosol. Add ammonia to the above silica hydrosol to adjust the pH to 8, and stir for 2 minutes to form a gel solution.

[0079] 2) The above gel solution and 80-120 mesh ceramsite were added to a fluidized bed at a mass ratio of 15:100. Fluidized spraying was carried out at 48°C and a flow rate of 1.2 m / s. After curing, a gel was formed. The gel was then aged at 48°C for 48 h and dried at 78°C for 12 h to form silica aerogel, thus obtaining a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating.

[0080] Example 10

[0081] A method for preparing a fracturing proppant that utilizes a hydrophobic aerogel coating to achieve slow settling includes the following steps:

[0082] 1) In a three-necked flask, add 0.05 mol trimethylmethoxysilane, 0.1 mol tetraethyl orthosilicate, 0.3 mol methyltriethoxysilane, and 0.5 mol ethyl acetate in sequence and stir until homogeneous. Then, add hydrochloric acid to the above mixed solution to adjust the pH value to 2, and hydrolyze it completely at 50°C to obtain silica hydrosol. Then, add ammonia water to the above silica hydrosol to adjust the pH value to 8, and stir for 2 minutes to form a gel solution.

[0083] 2) The above gel solution and 80-120 mesh ceramsite were added to a fluidized bed at a mass ratio of 5:100. Fluidized spraying was carried out at 49°C and a flow rate of 1.2 m / s. After curing, a gel was formed. The gel was then aged at 49°C for 48 h and dried at 79°C for 12 h to form silica aerogel, thus obtaining a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating.

[0084] Performance testing

[0085] To characterize the temperature resistance and suspension properties of the fracturing proppant with hydrophobic aerogel coating that achieves slow settling in water prepared according to the present invention, a static suspension test was conducted. The fracturing proppant with hydrophobic aerogel coating that achieves slow settling in the examples was taken and prepared into 100 mL of proppant-carrying solution with slickwater at a sand ratio of 20% (slickwater viscosity 2.1 mPa·s). The solution was stirred at 600 rpm for 2 min and then allowed to stand at different temperatures. The suspension state of the proppant-carrying solution after standing for 2 h at 60℃, 80℃, and 90℃ was tested. The results are shown in Table 1.

[0086] Table 1. Suspended state of fracturing proppants prepared in Examples 1-5 using hydrophobic aerogel coatings at different temperatures.

[0087]

[0088]

[0089] Table 1 shows the suspended sand state of the fracturing proppant with hydrophobic aerogel coating prepared in Examples 1-5 at different temperatures. As can be seen from Table 1, the fracturing proppant with hydrophobic aerogel coating prepared in this invention can be well suspended in water, with little effect from temperature, exhibiting good temperature resistance. Comparing Examples 1-3, sand sedimentation occurred in Example 1, possibly because the aerogel of the fracturing proppant with hydrophobic aerogel coating prepared in Example 1 contained less trimethylmethoxysilane, affecting the hydrophobicity of the coated aerogel and thus reducing the strength and thickness of the air film generated by the lotus leaf effect, resulting in poor suspension of the fracturing proppant with hydrophobic aerogel coating. Comparing Examples 2, 4, and 5, the fracturing proppant with hydrophobic aerogel coating prepared in Example 4 showed slight sedimentation, likely due to the smaller amount of aerogel used, but still possessed strong suspension ability.

[0090] In summary, this invention generates a lotus leaf effect by spraying a hydrophobic silica aerogel onto the proppant surface. The gas film generated by the lotus leaf effect and the porosity of the silica aerogel itself allow the fracturing proppant of this invention, which utilizes a hydrophobic aerogel coating for slow settling, to suspend freely in water. Therefore, the fracturing proppant obtained by this invention, which utilizes a hydrophobic aerogel coating for slow settling, is of great significance for increasing oil and gas reservoir production.

[0091] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating, characterized in that, Includes the following steps: S1: Trimethylmethoxysilane, organosilane coupling agent, methyltriethoxysilane, and organic solvent are stirred and mixed evenly. An acidic substance is added to adjust the pH to 2-3. After complete hydrolysis, silica hydrosol is obtained. Then, an alkaline substance is added to adjust the pH to 7-8. The mixture is stirred and mixed evenly to form a gel solution. The molar ratio of trimethylmethoxysilane: organosilane coupling agent: methyltriethoxysilane: organic solvent is (0.2-0.5): 1: 3:

5. S2: The proppant and the gel solution obtained in step S1 are mixed and fluidized sprayed. After curing, a gel is formed. After post-treatment, a silica aerogel is formed, and a fracturing proppant that achieves slow settling using a hydrophobic aerogel coating is obtained.

2. The method for preparing a slow-settling fracturing proppant using a hydrophobic aerogel coating according to claim 1, characterized in that, In step S1, the hydrolysis temperature is 45-55℃.

3. The method for preparing a slow-settling fracturing proppant using a hydrophobic aerogel coating according to claim 1, characterized in that, In step S1, the organosilane coupling agent is any one of tetraethyl orthosilicate, methyl orthosilicate, tetraethyl orthosilicate, and butyl orthosilicate; the organic solvent is any one of isopropanol, methanol, ethanol, cyclohexane, n-hexane, and ethyl acetate.

4. The method for preparing a slow-settling fracturing proppant using a hydrophobic aerogel coating according to claim 1, characterized in that, In step S1, the acidic substance is any one of hydrochloric acid, nitric acid, and oxalic acid; the alkaline substance is any one of ammonia, sodium carbonate, and sodium bicarbonate.

5. The method for preparing a slow-settling fracturing proppant using a hydrophobic aerogel coating according to claim 1, characterized in that, In step S2, the mass ratio of the gel solution to the support is (5-15):

100.

6. The method for preparing a slow-settling fracturing proppant using a hydrophobic aerogel coating according to claim 1, characterized in that, In step S2, the temperature of the fluidized spraying is 45-50℃ and the flow rate is 1.0~1.2m / s.

7. The method for preparing a slow-settling fracturing proppant using a hydrophobic aerogel coating according to claim 1, characterized in that, In step S2, the post-treatment includes aging at 45-50℃ for 48-60 hours and drying at 75-80℃ for 12-14 hours.

8. The method for preparing a slow-settling fracturing proppant using a hydrophobic aerogel coating according to claim 1, characterized in that, In step S2, the proppant is either 40-120 mesh quartz sand or ceramsite.

9. The fracturing proppant with slow-settling effect achieved by the preparation method according to any one of claims 1 to 8, characterized in that, It includes the inner core support particles, the middle outer aerogel coating layer, and the outermost air film based on the lotus effect.

10. The application of the hydrophobic aerogel coating-based slow-sinking proppant as described in claim 9 in hydraulic fracturing.

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