A hydrophobic polyurethane coating gas-suspended proppant based on lotus effect and a preparation method and application thereof

Abstract

The application discloses a kind of hydrophobic polyurethane coating gas-suspended proppant based on lotus effect and its preparation method and application, it is related to oil and gas well stimulation technical field.The application prepares the hydrophobic polyurethane coating gas-suspended proppant based on lotus effect by using fluidized bed to spray polyurethane mixed solution on the surface of proppant after hydrophobic modification of polyurethane.Because of the porous hydrophobic structure and special surface papillary structure of polyurethane itself, the surface of proppant coated by modified polyurethane will form a layer of gas film based on lotus effect, and finally form gas-suspended proppant that can freely suspend in low viscosity water or even clear water.The gas-suspended proppant coated by gas film and polyurethane has excellent suspensibility and stability, and can freely suspend in water, reduces the requirement for fluid viscoelasticity, can be applied to more fracturing scenes, and does not need to use a large amount of organic thickening agent, reduces the damage to reservoir, and the preparation process is simple, low in cost and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a hydrophobic polyurethane coating air suspension proppant based on the lotus effect, its preparation method, and its application. Background Technology

[0002] Hydraulic fracturing, a key measure for enhancing oil and gas field productivity, has achieved significant success in the field of oil and gas production enhancement. This technology involves injecting high-pressure fluid into the well using a surface pump unit to create fractures, while simultaneously injecting fluid carrying proppant to fill these fractures. After the wellhead is sealed, the fractures gradually close, with the proppant remaining within the fractures to prevent closure, thus forming stable, high-conductivity fracture channels and achieving the goal of increased production. During hydraulic fracturing, the effective suspension state of the proppant is crucial, as excessively rapid settling can hinder proppant entry into the fractures, thereby affecting the propping effect.

[0003] Currently, the main proppants used in fracturing technology include quartz sand, ceramsite, and their modified products. Traditional fracturing fluids require increasing the fluid viscosity to maintain proppant suspension; however, high-viscosity proppant-carrying fluids can lead to formation damage and blockage. Therefore, low-viscosity slickwater fracturing technology has become an efficient and economical development approach. To maintain good proppant suspension in low-viscosity fluids, current proppant improvements mainly focus on two directions. First, reducing the relative density of the proppant to improve its suspension, such as low-density and ultra-low-density proppants. However, the preparation process of these proppants is complex and costly, and they have low compressive strength and are prone to breakage. Second, coating the proppant surface with a chemical coating, which either hydrates and expands to reduce the relative density or dissolves in water and cross-links to increase the viscosity of the water. 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] In response to the technical problems of existing high-viscosity proppant-carrying fluids causing formation damage and blockage, the complex and costly preparation process of low-density and ultra-low-density proppants, their low compressive strength and easy breakage, and the easy deformation and unstable bonding of the chemical coating on the proppant surface, which may even cause blockage of pores and throats in fractures, there is an urgent need for a new technology to improve the suspension of proppants in order to solve the problems currently faced in the field of oil and gas well production enhancement technology. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a hydrophobic polyurethane coating air suspension proppant based on the lotus effect and its preparation method, in order to solve the technical problems of existing high-viscosity proppant fluid causing formation damage and blockage; low-density and ultra-low-density proppant preparation processes being complex and costly, and having low compressive strength and being prone to breakage; and chemical coatings applied to the proppant surface being prone to deformation, having unstable bonding with the proppant, and potentially causing blockage of pores and throats in fractures.

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

[0007] This invention discloses a method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect, comprising the following steps:

[0008] 1) Mix diisocyanate, polypropylene glycol, catalyst and solvent, heat and stir to react evenly, add fluorinated polysiloxane to obtain polyurethane prepolymer solution, then add chain extender and polymethyl methacrylate, stir to react evenly to obtain mixed solution;

[0009] 2) The mixed solution obtained in step 1) is mixed with the proppant and fluidized sprayed. After post-treatment, a hydrophobic polyurethane coating with lotus leaf effect is formed, and a hydrophobic polyurethane coating air suspension proppant based on lotus leaf effect is obtained.

[0010] Preferably, in step 1), the heating and stirring reaction conditions are: reacting at 70-85℃ for 2-3 hours; the stirring reaction conditions are: reacting at 50-60℃ for 3-5 hours.

[0011] Preferably, in step 1), the molar ratio of diisocyanate:polypropylene glycol:chain extender is 1:(0.8-1.1):(0.1-0.3).

[0012] Preferably, in step 1), the amount of catalyst added is 0.1%-0.5% of the sum of the mass of diisocyanate and polypropylene glycol; the amount of solvent added is 2-3 times the sum of the mass of diisocyanate and polypropylene glycol; the amount of fluorinated polysiloxane added is 5%-10% of the sum of the mass of diisocyanate and polypropylene glycol; and the amount of polymethyl methacrylate added is 40%-60% of the sum of the mass of diisocyanate and polypropylene glycol.

[0013] Preferably, in step 1), the diisocyanate includes any one or more combinations of isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; the catalyst is an organometallic catalyst, which is any one of dibutyltin dilaurate, stannous octoate, and stannous isooctanoate; the solvent is any one of N,N-dimethylformamide and N,N-dimethylacetamide; and the chain extender is any one or more combinations of 1,4-butanediol, 1,4-cyclohexanediol, ethylene glycol, propylene glycol, and neopentyl glycol.

[0014] Preferably, in step 2), the mass ratio of the mixed solution to the proppant is (10-20):100; the proppant is any one of 20-120 mesh quartz sand and ceramsite.

[0015] Preferably, in step 2), the temperature of fluidized spraying is 55-60℃ and the flow rate is 1.1-1.3m / s.

[0016] Preferably, in step 2), the post-treatment includes: aging at room temperature for 24-30 hours and drying in an oven at 65-75°C for 12-14 hours.

[0017] The present invention also discloses a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect prepared by the above preparation method.

[0018] The present invention also discloses the application of the above-mentioned hydrophobic polyurethane coating air suspension proppant based on the lotus effect in hydraulic fracturing.

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

[0020] This invention provides a method for preparing a hydrophobic polyurethane coating air-suspension proppant based on the lotus effect. Currently, few studies utilize gas-suspension proppant methods. As an innovative technology, gas-suspension proppants primarily modify the surface of the proppant to impart gas adsorption properties. After gas adsorption, the bulk density of the proppant decreases, allowing it to remain suspended in slickwater fracturing fluid or even clean water. This invention effectively enhances the suspension performance of the proppant by coating the surface of the proppant with a mixed solution of hydrophobic polyurethane. Firstly, the hydrophobic polyurethane coating easily adheres to the surface of quartz sand, and polyurethane itself has a natural cyclic porous structure, reducing the bulk density of the proppant coated with polyurethane. Secondly, by introducing low surface energy elements such as fluorine and silicon into the polyurethane chain segments to achieve hydrophobic modification, the superhydrophobic coating prepared by blending polymethyl methacrylate with polyurethane possesses a micro-nano-scale rough protrusion structure. These hydrophobic protrusions generate a lotus effect on the coating surface, thereby forming an air film. The preparation method disclosed in this invention is simple, low-cost and environmentally friendly. The resulting hydrophobic polyurethane coating air suspension proppant based on the lotus effect can be freely suspended in low-viscosity water or even clean water.

[0021] The present invention also discloses a hydrophobic polyurethane coating air suspension proppant based on the lotus effect prepared by the above preparation method, which has excellent suspension and stability. The proppant coated by the gas film and polyurethane 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 a large amount of organic thickener, thus reducing damage to the reservoir.

[0022] This invention also discloses the application of the above-mentioned hydrophobic polyurethane coating air suspension proppant based on the lotus effect in hydraulic fracturing. When applied, it can be freely suspended in low viscosity water or even clean water, which is of great significance for increasing the production of oil and gas reservoirs. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the hydrophobic polyurethane coating air suspension proppant based on the lotus effect disclosed in this invention. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] The present invention will now be described in further detail with reference to the accompanying drawings:

[0027] This invention also provides a method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus effect. The mechanism for forming the hydrophobic polyurethane coating air suspension proppant based on the lotus effect is as follows:

[0028] This invention modifies polyurethane by adding fluorinated polysiloxane and polymethyl methacrylate to achieve hydrophobicity and surface morphology modification. During the preparation process, before foaming and curing, a polyurethane mixture solution is uniformly sprayed onto the surface of the proppant using a fluidized bed. This produces a polyurethane coating that is hydrophobic, porous, and has a micro-nano rough surface structure. Due to the natural porous and hydrophobic structure of polyurethane itself and the special papillary structure formed on the surface, a lotus leaf effect will be generated on the surface, thereby forming an air film. Ultimately, a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect is formed, which can be freely suspended in low viscosity water or even clean water.

[0029] This invention also provides a method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus effect, comprising:

[0030] S1: Mix diisocyanate, polypropylene glycol, catalyst, and solvent evenly, react at 70-85℃ for 2-3 hours, then add fluorinated polysiloxane to obtain a polyurethane prepolymer solution; add chain extender and polymethyl methacrylate to the above prepolymer solution, stir and mix evenly, react at 50-60℃ for 3-5 hours to obtain a mixed solution.

[0031] S2: The above mixed solution and proppant are added to a fluidized bed and fluidized spraying is performed under certain operating conditions. After post-treatment, a hydrophobic polyurethane coating with lotus leaf effect is formed, resulting in a hydrophobic polyurethane coating slow-settling proppant based on lotus leaf effect.

[0032] In S2, the proppant is either 60-120 mesh quartz sand or ceramsite; the mass ratio of the mixed solution to the proppant is (10-20):100.

[0033] In S1, the diisocyanate includes any one or a combination of two or more of isophorone diisocyanate, toluene diisocyanate and diphenylmethane diisocyanate.

[0034] The catalyst is an organometallic catalyst, which is any one of dibutyltin dilaurate, stannous octanoate, and stannous isooctanoate.

[0035] The solvent is any one of N,N-dimethylformamide and N,N-dimethylacetamide;

[0036] The chain extender is any one or a combination of two or more of 1,4-butanediol, 1,4-cyclohexanediol, ethylene glycol, propylene glycol, and neopentyl glycol.

[0037] In S1, the molar ratio of diisocyanate:polypropylene glycol:chain extender is 1:(0.8-1.1):(0.1-0.3);

[0038] The catalyst addition amount is 0.1%-0.5% of the sum of the mass of diisocyanate and polypropylene glycol;

[0039] The amount of solvent added is 2-3 times the sum of the mass of diisocyanate and polypropylene glycol;

[0040] The amount of fluorinated polysiloxane added is 5%-10% of the total mass of diisocyanate and polypropylene glycol;

[0041] The amount of polymethyl methacrylate added is 40%-60% of the combined mass of diisocyanate and polypropylene glycol.

[0042] In S2, the fluidized bed operating temperature is 55-60℃, and the flow rate is controlled at 1.1-1.3m / s;

[0043] In S2, the post-treatment includes: aging at room temperature for 24-30 hours and drying in an oven at 65-75℃ for 12-14 hours;

[0044] In S2, the proppant is any one of 20-120 mesh quartz sand and ceramsite; the mass ratio of the mixed solution to the proppant is (10-20):100.

[0045] The hydrophobic polyurethane coating air suspension proppant based on the lotus effect prepared by this invention has excellent suspension and stability. The proppant coated by the air 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 a large amount of organic thickener, reducing damage to the reservoir. The preparation process is simple, low-cost and environmentally friendly.

[0046] See Figure 1 This is a schematic diagram of the structure of the hydrophobic polyurethane coating air suspension proppant based on the lotus effect disclosed in this invention. As can be seen from the figure, 1 is the air film generated based on the lotus effect; 2 is the core proppant particle; 3 is the outer hydrophobic polyurethane coating; and the right side is the microstructure model of the hydrophobic polyurethane.

[0047] Example 1

[0048] A method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect includes the following steps:

[0049] 1) Accurately weigh 20g of isophorone diisocyanate, 180g of polypropylene glycol with a molecular weight of 2000, 0.5g of dibutyltin dilaurate, and 500ml of N,N-dimethylformamide, stir and mix evenly, react at 80℃ for 2h, then add 10g of fluorinated polysiloxane to obtain a polyurethane prepolymer solution; add 1g of 1,4-butanediol and 80g of polymethyl methacrylate to the above prepolymer solution, stir and mix evenly, react at 60℃ for 3h to obtain a mixed solution;

[0050] 2) The above mixed solution and 80-120 mesh quartz sand were added to the fluidized bed at a mass ratio of 15:100. Fluidized spraying was carried out at 60°C and 1.2 m / s. The mixture was aged at room temperature for 24 h and dried in an oven at 65°C for 12 h to obtain a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect.

[0051] Example 2

[0052] A method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect includes the following steps:

[0053] 1) Accurately weigh 20g of isophorone diisocyanate, 180g of polypropylene glycol with a molecular weight of 2000, 0.5g of dibutyltin dilaurate, and 500ml of N,N-dimethylformamide, stir and mix evenly, react at 80℃ for 2h, then add 20g of fluorinated polysiloxane to obtain a polyurethane prepolymer solution; add 1g of 1,4-butanediol and 100g of polymethyl methacrylate to the above prepolymer solution, stir and mix evenly, react at 60℃ for 3h to obtain a mixed solution;

[0054] 2) The above mixed solution and 80-120 mesh quartz sand were added to the fluidized bed at a mass ratio of 15:100. Fluidized spraying was carried out at 60°C and 1.2 m / s. The mixture was aged at room temperature for 24 h and dried in an oven at 68°C for 12 h to obtain a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect.

[0055] Example 3

[0056] A method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect includes the following steps:

[0057] 1) Accurately weigh 20g of isophorone diisocyanate, 180g of polypropylene glycol with a molecular weight of 2000, 0.5g of dibutyltin dilaurate, and 500ml of N,N-dimethylformamide, stir and mix evenly, react at 80℃ for 2h, then add 20g of fluorinated polysiloxane to obtain a polyurethane prepolymer solution; add 1g of 1,4-butanediol and 150g of polymethyl methacrylate to the above prepolymer solution, stir and mix evenly, react at 60℃ for 3h to obtain a mixed solution;

[0058] 2) The above mixed solution and 80-120 mesh quartz sand were added to the fluidized bed at a mass ratio of 15:100. Fluidized spraying was carried out at 60°C and 1.2 m / s. The mixture was aged at room temperature for 24 h and dried in an oven at 75°C for 12 h to obtain a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect.

[0059] Example 4

[0060] A method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect includes the following steps:

[0061] 1) Accurately weigh 20g of isophorone diisocyanate, 180g of polypropylene glycol with a molecular weight of 2000, 0.5g of dibutyltin dilaurate, and 500ml of N,N-dimethylformamide, stir and mix evenly, react at 80℃ for 2h, then add 20g of fluorinated polysiloxane to obtain a polyurethane prepolymer solution; add 1g of 1,4-butanediol and 100g of polymethyl methacrylate to the above prepolymer solution, stir and mix evenly, react at 60℃ for 3h to obtain a mixed solution;

[0062] 2) The above mixed solution and 80-120 mesh quartz sand were added to the fluidized bed at a mass ratio of 10:100. Fluidized spraying was carried out at 60°C and 1.2 m / s. The mixture was aged at room temperature for 24 h and dried in an oven at 70°C for 12 h to obtain a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect.

[0063] Example 5

[0064] A method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect includes the following steps:

[0065] 1) Accurately weigh 20g of isophorone diisocyanate, 180g of polypropylene glycol with a molecular weight of 2000, 0.5g of dibutyltin dilaurate, and 500ml of N,N-dimethylformamide, stir and mix evenly, react at 80℃ for 2h, then add 20g of fluorinated polysiloxane to obtain a polyurethane prepolymer solution; add 1g of 1,4-butanediol and 100g of polymethyl methacrylate to the above prepolymer solution, stir and mix evenly, react at 60℃ for 3h to obtain a mixed solution;

[0066] 2) The above mixed solution and 80-120 mesh quartz sand were added to the fluidized bed at a mass ratio of 20:100. Fluidized spraying was carried out at 60°C and 1.2 m / s. The mixture was aged at room temperature for 24 h and dried in an oven at 72°C for 12 h to obtain a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect.

[0067] Example 6

[0068] A method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect includes the following steps:

[0069] 1) Accurately weigh 17.5g toluene diisocyanate, 160g polypropylene glycol with a molecular weight of 2000, 0.18g dibutyltin dilaurate, and 500ml N,N-dimethylacetamide, stir and mix evenly, react at 70℃ for 2h, then add 8.9g fluorinated polysiloxane to obtain a polyurethane prepolymer solution; add 1.2g 1,4-cyclohexanediol and 70g polymethyl methacrylate to the above prepolymer solution, stir and mix evenly, react at 50℃ for 3h to obtain a mixed solution;

[0070] 2) The above mixed solution and 80-120 mesh ceramsite were added to the fluidized bed at a mass ratio of 10:100. Fluidized spraying was carried out at 55°C and 1.1 m / s. The mixture was aged at room temperature for 24 h and dried in an oven at 65°C for 12 h to obtain a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect.

[0071] Example 7

[0072] A method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect includes the following steps:

[0073] 1) Accurately weigh 25g of diphenylmethane diisocyanate, 220g of polypropylene glycol with a molecular weight of 2000, 1.23g of dibutyltin dilaurate, and 500ml of N,N-dimethylformamide, stir and mix evenly, react at 85℃ for 3h, then add 24.5g of fluorinated polysiloxane to obtain a polyurethane prepolymer solution; add 1.9g of ethylene glycol and 147g of polymethyl methacrylate to the above prepolymer solution, stir and mix evenly, react at 60℃ for 5h to obtain a mixed solution;

[0074] 2) The above mixed solution and 80-120 mesh quartz sand were added to the fluidized bed at a mass ratio of 20:100. Fluidized spraying was carried out at 56°C and 1.3 m / s. The mixture was aged at room temperature for 24 h and dried in an oven at 75°C for 14 h to obtain a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect.

[0075] Example 8

[0076] A method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect includes the following steps:

[0077] 1) Accurately weigh 20g of isophorone diisocyanate, 180g of polypropylene glycol with a molecular weight of 2000, 0.5g of stannous isooctanoate, and 500ml of N,N-dimethylformamide, stir and mix evenly, react at 80℃ for 2h, then add 20g of fluorinated polysiloxane to obtain a polyurethane prepolymer solution; add 1g of propylene glycol and 100g of polymethyl methacrylate to the above prepolymer solution, stir and mix evenly, react at 60℃ for 3h to obtain a mixed solution;

[0078] 2) The above mixed solution and 80-120 mesh quartz sand were added to the fluidized bed at a mass ratio of 16:100. Fluidized spraying was carried out at 57°C and 1.3 m / s. The mixture was aged at room temperature for 24 h and dried in an oven at 68°C for 12 h to obtain a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect.

[0079] Example 9

[0080] A method for preparing a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect includes the following steps:

[0081] 1) Accurately weigh 20g of isophorone diisocyanate, 180g of polypropylene glycol with a molecular weight of 2000, 0.5g of stannous octoate, and 500ml of N,N-dimethylformamide, stir and mix evenly, react at 80℃ for 2h, then add 20g of fluorinated polysiloxane to obtain a polyurethane prepolymer solution; add 1g of neopentyl glycol and 100g of polymethyl methacrylate to the above prepolymer solution, stir and mix evenly, react at 60℃ for 3h to obtain a mixed solution;

[0082] 2) The above mixed solution and 80-120 mesh quartz sand were added to the fluidized bed at a mass ratio of 18:100. Fluidized spraying was carried out at 60°C and 1.1 m / s. The mixture was aged at room temperature for 24 h and dried in an oven at 68°C for 12 h to obtain a hydrophobic polyurethane coating air suspension proppant based on the lotus leaf effect.

[0083] Performance testing

[0084] To characterize the temperature resistance and suspension properties of the hydrophobic polyurethane coating air suspension proppant based on the lotus effect of the present invention in water, a static suspension test was conducted. The hydrophobic polyurethane coating air suspension proppant based on the lotus effect from the examples was taken and prepared into 100 ml sand-carrying solution with slickwater at a sand ratio of 20% (viscosity of 2.2 mPa·s). The solution was stirred at 600 rpm for 2 minutes and then allowed to stand at different temperatures. The suspended sand state of the sand-carrying solution was tested at 60℃, 80℃, and 90℃ for 3 hours. The results are shown in Table 1.

[0085] Table 1

[0086]

[0087] As shown in Table 1, the hydrophobic polyurethane coating air suspension proppant based on the lotus effect prepared in this invention can be well suspended in water, with little effect from temperature and good temperature resistance. Comparing Examples 1-3, sand sedimentation occurred in Example 1, possibly because the polyurethane coating in Example 1 contained less fluorinated polysiloxane and polymethyl methacrylate, affecting the hydrophobicity and surface papillary structure of the polyurethane coating, thus reducing the strength and thickness of the air film generated by the lotus effect, resulting in poor suspension performance. Comparing Examples 2, 4, and 5, a small amount of sedimentation occurred in Example 4, likely due to the small amount of polyurethane coating used, but it still exhibited strong suspension capacity.

[0088] In summary, the present invention, by spraying a polyurethane coating with hydrophobicity, porosity, and a papillary surface structure onto the proppant surface, generates a lotus leaf effect. The gas film generated by this lotus leaf effect, combined with the porosity of the polyurethane itself, allows the hydrophobic polyurethane coating air-suspension proppant of this invention to suspend freely in water. This invention is of great significance for increasing oil and gas reservoir production.

[0089] 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 hydrophobic polyurethane coating air suspension proppant based on the lotus effect, characterized in that, Includes the following steps: 1) Diisocyanate, polypropylene glycol, catalyst, and solvent are mixed, heated, and stirred until homogeneous. Fluorinated polysiloxane is added to obtain a polyurethane prepolymer solution. Then, chain extender and polymethyl methacrylate are added, and the mixture is stirred until homogeneous to obtain a mixed solution. The amount of catalyst added is 0.1%-0.5% of the sum of the mass of diisocyanate and polypropylene glycol; the amount of solvent added is 2-3 times the sum of the mass of diisocyanate and polypropylene glycol; the amount of fluorinated polysiloxane added is 5%-10% of the sum of the mass of diisocyanate and polypropylene glycol; and the amount of polymethyl methacrylate added is 40%-60% of the sum of the mass of diisocyanate and polypropylene glycol. 2) The mixed solution obtained in step 1) is mixed with the proppant and fluidized sprayed. After post-treatment, a hydrophobic polyurethane coating with lotus effect is formed, and a hydrophobic polyurethane coating air suspension proppant based on lotus effect is obtained.

2. The preparation method of the hydrophobic polyurethane coating air suspension support based on the lotus effect according to claim 1, characterized in that, In step 1), the conditions for the heating and stirring reaction are: reacting at 70-85℃ for 2-3 hours; the conditions for the stirring reaction are: reacting at 50-60℃ for 3-5 hours.

3. The preparation method of the hydrophobic polyurethane coating air suspension support based on the lotus effect according to claim 1, characterized in that, In step 1), the molar ratio of diisocyanate:polypropylene glycol:chain extender is 1:(0.8-1.1):(0.1-0.3).

4. The preparation method of the hydrophobic polyurethane coating air suspension support based on the lotus effect according to claim 1, characterized in that, In step 1), the diisocyanate includes any one or more combinations of isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; the catalyst is an organometallic catalyst, which is any one of dibutyltin dilaurate, stannous octoate, and stannous isooctanoate; the solvent is any one of N,N-dimethylformamide and N,N-dimethylacetamide; and the chain extender is any one or more combinations of 1,4-butanediol, 1,4-cyclohexanediol, ethylene glycol, propylene glycol, and neopentyl glycol.

5. The method for preparing the hydrophobic polyurethane coating air suspension support based on the lotus effect according to claim 1, characterized in that, In step 2), the mass ratio of the mixed solution to the proppant is (10-20):100; the proppant is any one of 20-120 mesh quartz sand and ceramsite.

6. The preparation method of the hydrophobic polyurethane coating air suspension support based on the lotus effect according to claim 1, characterized in that, In step 2), the temperature of the fluidized spraying is 55-60℃ and the flow rate is 1.1~1.3m / s.

7. The preparation method of the hydrophobic polyurethane coating air suspension support based on the lotus effect according to claim 1, characterized in that, In step 2), the post-treatment includes: aging at room temperature for 24-30 hours and drying in an oven at 65-75°C for 12-14 hours.

8. The hydrophobic polyurethane coating air suspension proppant based on the lotus effect prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the hydrophobic polyurethane coating air suspension proppant based on the lotus effect as described in claim 8 in hydraulic fracturing.

Images