A low-density proppant and preparation method thereof

Abstract

The disclosed embodiment provides a low-density proppant and a preparation method thereof, the method comprising: uniformly mixing nutshell particles with a particle size range of 106 μm to 710 μm and a thermosetting phenolic resin with a preset solid content in a mass ratio of 10: (2 to 5), impregnating and stirring until there is no obvious liquid on the surface, to obtain a first semi-finished particle; transferring the first semi-finished particle into a granulator, adding a certain amount of coating material or a binder and nutshell powder, stirring until the particle surface is smooth, and then curing at a preset temperature for a certain period of time, and obtaining a low-density proppant after screening. In the preparation method of the disclosed embodiment, low-density nutshell particles are used as proppant particles, which are impregnated in a phenolic resin to increase the particle strength, and then coated with a binder and a nutshell powder or a coating material with a low density to improve the sphericity of the particles, thereby obtaining a proppant with high strength and low density, thereby reducing the requirements of the proppant for pumping and fracturing fluid performance.

Description

Technical Field

[0001] The disclosed embodiments belong to the technical field of proppants for oil and gas wells, and specifically relate to a low-density proppant and a preparation method thereof. Background Art

[0002] Fracturing is an important technology for increasing the production of oil and natural gas wells. Proppant is a key material for fracturing. Proppant is carried into the cracks of the fracturing formation by the fracturing fluid, thereby effectively introducing oil and gas into the oil and gas well, greatly increasing oil and gas production and extending the life of the oil and gas well.

[0003] At present, the commonly used fracturing proppants include quartz sand, expanded clay and resin-coated particles. Among them, quartz sand is the cheapest, has a low relative density, and is easy to construct and pump. However, quartz sand has low strength, poor sphericity, and a high crushing rate, which reduces the conductivity of the fracture and is particularly unsuitable for deep wells with high closure pressure. After the quartz sand is coated with resin, the sphericity is improved, the ability to resist crushing is greatly improved, and the conductivity is better than that of quartz sand, but still lower than that of expanded clay. The expanded clay proppant made of bauxite as the main material has better sphericity, crushing resistance and conductivity than quartz sand, and is widely used in deep oil and gas wells. However, the density of expanded clay (the apparent density is generally greater than 3.0g / cm 3 ) than quartz sand (apparent density is generally greater than 2.65g / cm 3 The proppant has a large diameter (about 2.5mm), which puts forward higher requirements on the pumping conditions and the performance of the fracturing fluid, and increases the difficulty of construction; it is easy to produce shorter support belts in the application, which accumulate at the port of the fracture, which is extremely unfavorable for diversion, thus affecting the later oil production effect. In contrast, low-density proppants have a better porosity and are easier to carry. They can greatly reduce the viscosity of the fracturing fluid, reduce damage to pipelines and pumps, and can even achieve clean water fracturing, effectively reducing the difficulty of construction and oil production costs; in addition, the diversion decline rate of low-density proppants is relatively low, which can produce good oil production effects. Therefore, the development of low-density proppants has become the direction of proppant research. Moreover, traditional proppants need to be sintered at high temperatures, which increases energy consumption.

[0004] There are at least the following problems in the prior art: there is a lack of a proppant that can ensure strength, reduce density, and thus reduce pumping and fracturing fluid performance requirements, so that construction costs can be reduced; and the proppant can avoid high-temperature sintering and save energy. Summary of the invention

[0005] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art and provide a low-density proppant and a method for preparing the same.

[0006] One aspect of the present disclosure provides a method for preparing a low-density proppant. The method comprises:

[0007] The nut shell particles with a particle size range of 106 μm to 710 μm and the thermosetting phenolic resin with a preset solid content are uniformly mixed in a mass ratio of 10:(2-5), and the mixture is immersed and stirred until there is no obvious liquid on the surface to obtain the first semi-finished particles;

[0008] The first semi-finished product particles are transferred into a high-speed granulator, and wood powder or nut shell powder having a mass ratio of (2-3) to (60-75) of the first semi-finished product particles and a particle size of not more than 45 μm is added, and after being evenly dispersed, the particles are heated and cured for 30 minutes to 60 minutes to obtain second semi-finished product particles;

[0009] The second semi-finished product particles are transferred to the high-speed granulator, a certain amount of binder is added, and the mixture is stirred evenly; a certain amount of nut shell powder is added, and the mixture is stirred until the nut shell powder is completely coated on the particles, and the rotation speed is reduced to a preset speed, and a certain amount of powder is added and dispersed, and the mixture is transferred to the low-speed granulator;

[0010] The particles are transferred in the low-speed granulator until the surface of the particles is smooth, and then cured at a preset temperature for a certain period of time, and then sieved to obtain a low-density proppant.

[0011] Optionally, the binder is prepared by the following steps:

[0012] Liquid bisphenol A epoxy resin and liquid modified diaminodiphenylmethane with a preset viscosity are uniformly mixed in a mass ratio of 100:(10-30) to obtain a binder.

[0013] Optionally, the mass ratio of the second semi-finished product particles, the binder and the nut shell powder is (125-155): (2-7): (10-40).

[0014] Optionally, the preset rotation speed is 500 rpm to 1000 rpm.

[0015] Optionally, the parameters of the low-density proppant include:

[0016] Bulk density range is 0.85g / cm 3 ~1.0g / cm 3 , apparent density range is 1.15g / cm 3 ~1.35g / cm 3 , acid solubility range is 1% to 4%, sphericity range is 0.7 to 0.9, and 52MPa crushing rate range is 4% to 9%.

[0017] Another aspect of the disclosed embodiments provides a method for preparing a low-density proppant. The method comprises:

[0018] The nut shell particles with a particle size range of 106 μm to 710 μm and the thermosetting phenolic resin with a preset solid content are uniformly mixed in a mass ratio of 10:(2-5), and the mixture is immersed and stirred until there is no obvious liquid on the surface to obtain the first semi-finished particles;

[0019] The first semi-finished particles are transferred into a granulator, a certain amount of coating layer material is added, and the particles are transferred in the granulator until the fine particles are completely adhered to the surface of the coarse particles. At the same time, a certain amount of powder is added, and the particles are further transferred until the surface is smooth. The particles are then cured at a preset temperature for a certain period of time, and a low-density proppant is obtained after screening.

[0020] Optionally, the coating layer material is prepared by the following steps:

[0021] The husk powder with a particle size not greater than 45 μm and the thermosetting phenolic resin with a solid content of 50% to 70% are mixed in a mass ratio of 2:(0.5 to 1.5), and then soaked for a certain period of time to obtain a coating layer material.

[0022] Optionally, the mass ratio of the first semi-finished product particles to the coating layer material is (12-15): (2-3).

[0023] Optionally, the parameters of the low-density proppant include:

[0024] Bulk density range is 0.8g / cm 3 ~0.95g / cm 3 , apparent density range is 1.05g / cm 3 ~1.25g / cm 3 , acid solubility range is 1% to 4%, sphericity range is 0.7 to 0.85, and 52MPa crushing rate range is 6% to 9%.

[0025] Another aspect of the disclosed embodiment provides a low-density proppant, which is prepared by the preparation method described above.

[0026] In a method for preparing a low-density proppant according to an embodiment of the present disclosure, nut shell particles are impregnated with a thermosetting phenolic resin to allow it to penetrate into the micropores of the nut shell particles, thereby improving the strength of the nut shell particles; a binder and nut shell powder or a coating material is further coated on the surface of the particles to repair defects on the surface of the particles, thereby increasing the amount of material coating on the surface of the particles and improving the sphericity and strength of the particles; and the method of the embodiment of the present disclosure has low energy consumption, and only low-temperature heating is performed, and high-temperature sintering is not required. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic flow chart of a method for preparing a low-density proppant according to an embodiment of the present disclosure;

[0028] Figure 2 The present invention is a schematic flow chart of a method for preparing a low-density proppant according to another embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solutions of the embodiments of the present disclosure, the embodiments of the present disclosure are further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0030] like Figure 1 As shown, a method for preparing an ultra-low density proppant, the method S100 comprises:

[0031] S110, uniformly mix nut shell particles with a particle size range of 106 μm to 710 μm and thermosetting phenolic resin with a preset solid content in a mass ratio of 10:(2-5), soak and stir until there is no obvious liquid on the surface, to obtain first semi-finished particles.

[0032] As an example, the nut shell particles can be one or more of walnut shells, apricot shells, peach shells, hazelnut shells and macadamia shells. The nut shell particles are crushed and can be directly purchased on the market. Nut shell particles with a desired particle size range can also be obtained by using existing nut shell particle processing methods, which will not be described here.

[0033] In the disclosed embodiment, 1 kg of nut shell particles with a particle size range of 106 μm to 710 μm can be evenly mixed with 200 g to 500 g of thermosetting phenolic resin with a solid content of 50% to 70%, and impregnated and stirred until there is no obvious liquid on the surface of the particles to obtain the first semi-finished particles. It should be noted that the thermosetting phenolic resin can impregnate the nut shell particles, penetrate into the micropores of the nut shell particles, and improve the particle strength. When stirring until there is no obvious liquid on the surface of the particles, it means that the thermosetting phenolic resin has penetrated into the micropores of the nut shell particles.

[0034] S120, transferring the first semi-finished product particles into a high-speed granulator, adding wood powder or nut shell powder with a mass ratio of (2-3): (60-75) to the first semi-finished product particles and a particle size not greater than 45 μm, and heating and curing for 30 min to 60 min after uniform dispersion to obtain second semi-finished product particles.

[0035] As an example, the high-speed granulator can be a granulation device with a rotation speed of up to 3000 rpm, so this high-speed granulator can also be called a strong granulator or a mixed granulator. The high-speed granulator has three functions of stirring, granulating and coating. Here, the rotation speed of the high-speed granulator can be about 1800 rpm, which is mainly used for coating the surface of the first semi-finished particles with wood powder or nut shell powder. Nut shell powder can also be replaced with bakelite powder. The disclosed embodiment can add 50g of wood powder or nut shell powder with a particle size not greater than 45μm, and heat to 80℃~160℃ after uniform dispersion for 0.2h~3h, and heat to promote the curing of the thermosetting phenolic resin. The wood powder or nut shell powder mainly plays a role in dispersing the particles to prevent the particles from sticking together during the heating and curing process.

[0036] S130, transferring the second semi-finished product particles into the high-speed granulator, adding a certain amount of binder, and stirring evenly; then adding a certain amount of nut shell powder, stirring until the nut shell powder is completely coated on the particles, reducing the speed to a preset speed, adding a certain amount of powder, dispersing, and transferring the particles into the low-speed granulator.

[0037] As an example, at this time, the high-speed granulator can be the same as the previous high-speed granulator, and the speed is set to about 1800 rpm. The nut shell powder can also be replaced with bakelite powder. In the embodiment of the present disclosure, 30g of binder can be added and stirred evenly, and then 150g of nut shell powder with a particle size of no more than 45μm can be added, and stirred until the nut shell powder is completely coated on the particles. The binder bonds the nut shell powder to the surface of the particles, repairs the defects on the surface of the particles, and improves the sphericity of the particles. In order to improve the sphericity of the particles, 30g of binder can be added and stirred evenly, and then 150g of nut shell powder with a particle size of no more than 45μm can be added, and stirred until the nut shell powder is completely coated on the particles. The embodiment of the present disclosure can add binders and nut shell powder in multiple times according to actual needs, and the number of times the binder and nut shell powder are added is not limited. In the disclosed embodiment, the speed of the high-speed granulator is reduced to a preset speed of 500 to 1000 rpm, and then 50g to 100g of powder is added and dispersed, and then the powder is transferred to a low-speed granulator for granulation. The speed range of the low-speed granulator is 30 to 50 rpm. The powder can be one or more of nut shell powder, quartz powder, active silicon powder, floating beads, etc., with a particle size not greater than 45 microns. The quartz powder, active silicon powder and floating beads are acid-resistant powders, which can prevent particles from sticking together and improve the acid resistance of the particles. The low-speed granulator can be a disc granulator or a round pot granulator. The speed of the disc granulator or the round pot granulator is relatively low, generally only a few dozen rpm, and is mainly used for granulation.

[0038] Exemplarily, the mass ratio of the second semi-finished product particles, the binder and the nut shell powder is (125-155): (2-7): (10-40).

[0039] As an example, the binder and the nut shell powder can be added to the high-speed granulator once or twice according to the above mass ratio, which can be adjusted according to actual conditions and will not be described in detail here.

[0040] Exemplarily, the preset rotation speed may be 500 rpm to 1000 rpm.

[0041] As an example, the preset rotation speed is a relatively low rotation speed, and the powder is poured in to disperse and prevent particles from sticking together.

[0042] Exemplarily, the binder is prepared by the following steps:

[0043] Liquid bisphenol A epoxy resin and liquid modified diaminodiphenylmethane with a preset viscosity are uniformly mixed in a mass ratio of 100:(10-30) to obtain a binder.

[0044] As an example, the adhesive can be prepared in advance. The preset viscosity is 0.5 Pa·S to 2 Pa·S, and the adhesive is preferably used up within 4 hours.

[0045] S140, granulating in the low-speed granulator until the granules have smooth surfaces, then curing at a preset temperature for a certain period of time, and obtaining a low-density proppant after screening.

[0046] As an example, the granulation time in the low-speed granulator can be set according to the actual situation, and the granulation is performed until the surface of the granules is smooth. The preset temperature of the embodiment of the present disclosure is in the range of 100°C to 400°C, and the curing time is in the range of 1h to 4h.

[0047] Exemplarily, the parameters of the low-density proppant include:

[0048] Bulk density range is 0.85g / cm 3 ~1.0g / cm 3 , apparent density range is 1.15g / cm 3 ~1.35g / cm 3 , acid solubility range is 1% to 4%, sphericity range is 0.7 to 0.9, and 52MPa crushing rate range is 4% to 9%.

[0049] As an example, the parameters of the proppant prepared by the preparation method of the embodiment of the present disclosure are shown above. The proppant prepared by the above preparation method reduces the proppant density to the maximum extent while ensuring the strength of the proppant, thereby reducing the requirements of the proppant on pumping and fracturing fluid performance, while reducing construction costs, and obtaining better oil recovery effects.

[0050] Another aspect of the disclosed embodiment provides a low-density proppant, which is prepared by the preparation method described above.

[0051] like Figure 2 As shown, another embodiment of the present disclosure provides a method for preparing an ultra-low density proppant, the method S200 comprising:

[0052] S210, uniformly mix nut shell particles with a particle size range of 106 μm to 710 μm and a thermosetting phenolic resin with a preset solid content in a mass ratio of 10:(2-5), soak and stir until there is no obvious liquid on the surface, and obtain first semi-finished particles.

[0053] As an example, the nut shell particles can be one or more of walnut shells, apricot shells, peach shells, hazelnut shells and macadamia shells. In another embodiment of the present disclosure, 1 kg of nut shell particles with a particle size range of 106 μm to 710 μm can be evenly mixed with 200 g to 500 g of thermosetting phenolic resin with a solid content of 50% to 70%, and impregnated and stirred until there is no obvious liquid on the surface of the particles to obtain the first semi-finished particles. Similarly, the thermosetting phenolic resin can impregnate the nut shell particles, penetrate into the micropores of the nut shell particles, and improve the particle strength.

[0054] S220, transferring the first semi-finished product particles into a granulator, adding a certain amount of coating layer material, and granulating in the granulator until fine particles are completely adhered to the surface of coarse particles, adding a certain amount of powder, and continuing to granulate until the surface of the particles is smooth, and then curing at a preset temperature for a certain period of time, and obtaining a low-density proppant after screening.

[0055] As an example, the granulator can be a granulator with a rotation speed of several thousand rpm. The rotation speed of the granulator can reach about 1800 rpm, and the coating material is mainly coated on the surface of the first semi-finished particle. In another embodiment of the present disclosure, 200g to 300g of coating material is added, and the granulator is used to turn the fine particles to completely adhere to the surface of the coarse particles. At the same time, 50g of powder is added, and the particles are turned until the surface is smooth. Then, the temperature is preset in the range of 100°C to 400°C, and the curing time is in the range of 1h to 4h. After screening, a low-density proppant is obtained. The powder can be one or more of nutshell powder, quartz powder, active silicon powder, floating beads, etc., with a particle size not exceeding 45μm. The quartz powder, active silicon powder and floating beads are acid-resistant powders.

[0056] Exemplarily, the coating layer material is prepared by the following steps:

[0057] The husk powder with a particle size not greater than 45 μm and the thermosetting phenolic resin with a solid content of 50% to 70% are mixed in a mass ratio of 2:(0.5 to 1.5), and then soaked for a certain period of time to obtain a coating layer material.

[0058] The coating layer material of another embodiment of the present disclosure can be prepared in advance, and 1 kg of husk powder with a particle size of no more than 45 μm and 500 g of thermosetting phenolic resin with a solid content of 50% to 70% can be evenly mixed and then soaked for 2 hours for later use.

[0059] Exemplarily, the mass ratio of the first semi-finished product particles to the coating layer material is (12-15): (2-3).

[0060] Exemplarily, the parameters of the low-density proppant include:

[0061] Bulk density range is 0.8g / cm 3 ~0.95g / cm 3 , apparent density range is 1.05g / cm 3 ~1.25g / cm 3 , acid solubility range is 1% to 4%, sphericity range is 0.7 to 0.85, and 52MPa crushing rate range is 6% to 9%.

[0062] As an example, the parameters of the proppant prepared by the preparation method of another embodiment of the present disclosure are shown above. The proppant prepared by the above preparation method reduces the proppant density to the maximum extent while ensuring the strength of the proppant, thereby reducing the requirements of the proppant on pumping and fracturing fluid performance, while reducing construction costs, and obtaining better oil recovery effects.

[0063] Another aspect of another embodiment of the present disclosure provides a low-density proppant, which is prepared by the preparation method described above.

[0064] The two methods for preparing proppants disclosed in the present invention both adopt composite coating technology to first mix nut shell particles with thermosetting phenolic resin to enhance the strength of nut shell particles; then, a coating layer material composed of nut shell powder and thermosetting phenolic resin with low density or nut shell powder and a binder is coated on the surface of nut shell particles to increase the coating amount of the particle surface material, effectively fill the surface defects of the particles, thereby improving the sphericity and strength. The present invention adopts nut shell particles, nut shell powder and thermosetting phenolic resin as the main raw materials, replaces the traditional bauxite, effectively reduces the density of the proppant, impregnates the nut shell particles in thermosetting phenolic resin to increase the particle strength, adopts composite coating technology to improve the particle sphericity, does not require high temperature sintering, only performs low temperature heating, has low energy consumption, and the obtained proppant has high strength and low density, reduces the requirements of the proppant on pumping and fracturing fluid performance, and reduces the construction cost at the same time, and obtains a better oil recovery effect.

[0065] Example 1

[0066] S110, weigh 1 kg of nut shell particles with a particle size range of 425 μm to 710 μm, and mix 250 g of thermosetting phenolic resin with a solid content of 50% to 70% evenly, soak and stir until there is no obvious liquid on the surface, to obtain the first semi-finished particles.

[0067] S120, transferring the first semi-finished product particles into a high-speed granulator, adding 50 g of walnut shell powder with a particle size of no more than 45 μm, dispersing evenly, heating to 120° C. and curing for 30 to 60 minutes to obtain second semi-finished product particles.

[0068] S130, then transfer the second semi-finished product particles into a high-speed granulator, add 30g of a binder and stir evenly, then add 150g of nut shell powder with a particle size of no more than 45μm, stir until it is completely coated on the particles, then add 30g of a binder and stir evenly, then add 150g of nut shell powder with a particle size of no more than 45μm, stir until it is completely coated on the particles, reduce the speed, add 50g of glass beads to disperse, and then transfer it to a low-speed granulator (the low-speed granulator can be a disc granulator or a round pot granulator).

[0069] The speed of the high-speed granulator can be about 1800 rpm. After the nut shell powder and the binder are coated on the particles, the speed can be reduced to 500 rpm, 50 g of glass beads are added for dispersion, and then the particles are transferred to the low-speed granulator.

[0070] S140, transfer in a low-speed granulator until the particle surface is smooth, then heat to 120°C and cure for 2 hours, and obtain a low-density proppant after sieving through a 425μm-850μm sieve.

[0071] The speed range of the low-speed granulator is 30 rpm, and the speed can be determined according to actual conditions, which will not be described in detail here.

[0072] The binder is prepared by the following steps:

[0073] Liquid bisphenol A epoxy resin and liquid modified diaminodiphenylmethane with a viscosity of 0.5Pa·S to 2Pa·S are mixed evenly in a mass ratio of 100:15, and stirred evenly to obtain an adhesive. The adhesive is prepared in advance and preferably used up within 4 hours.

[0074] The parameters of the low-density proppant obtained here include: bulk density of 0.85 g / cm 3 , apparent density is 1.15g / cm 3 , acid solubility is 1.4%, sphericity is 0.8, and 52MPa crushing rate is 7.5%.

[0075] Example 2

[0076] S110, weigh 1 kg of nut shell particles with a particle size range of 425 μm to 710 μm, and mix 250 g of thermosetting phenolic resin with a solid content of 50% to 70% evenly, soak and stir until there is no obvious liquid on the surface, to obtain the first semi-finished particles.

[0077] S120, transferring the first semi-finished product particles into a high-speed granulator, adding 50 g of walnut shell powder with a particle size of no more than 45 μm, dispersing evenly, heating to 120° C. and curing for 30 to 60 minutes to obtain second semi-finished product particles.

[0078] S130, then transferring the second semi-finished product particles into a high-speed granulator, adding 30g of a binder and stirring evenly, then adding 150g of nut shell powder with a particle size of no more than 45μm, stirring until all of them are coated on the particles, then adding 30g of a binder and stirring evenly, then adding 150g of nut shell powder with a particle size of no more than 45μm, stirring until all of them are coated on the particles, reducing the speed, adding 50g of quartz powder, dispersing, and then transferring it to a low-speed granulator (the low-speed granulator is a disc granulator or a round pot granulator).

[0079] The speed of the high-speed granulator can be about 1800 rpm. After the nut shell powder and the binder are coated on the particles, the speed can be reduced to 800 rpm, 50 g of glass beads are added for dispersion, and then the particles are transferred to the low-speed granulator.

[0080] S140, transfer in a low-speed granulator until the particle surface is smooth, then heat to 120°C and cure for 2 hours, and obtain a low-density proppant after sieving through a 425μm-850μm sieve.

[0081] The speed range of the low-speed granulator is 50 rpm, and the speed can be determined according to actual conditions, which will not be described in detail here.

[0082] The binder is prepared by the following steps:

[0083] Liquid bisphenol A epoxy resin and liquid modified diaminodiphenylmethane with a viscosity of 0.5Pa·S to 2Pa·S are mixed evenly in a mass ratio of 100:20, and stirred evenly to obtain an adhesive. The adhesive is prepared in advance and preferably used up within 4 hours.

[0084] The parameters of the low-density proppant here include: bulk density of 0.95 g / cm 3 Apparent density is 1.25g / cm 3 , acid solubility is 1.3%, sphericity is 0.9, and 52MPa crushing rate is 6.5%.

[0085] Example 3

[0086] S210, weighing 1 kg of nut shell particles with a particle size range of 300 μm to 500 μm, and 200 g of thermosetting phenolic resin with a solid content of 50% to 70% are mixed evenly, and the mixture is immersed and stirred until there is no obvious liquid on the surface to obtain the first semi-finished particles.

[0087] S220, transfer the first semi-finished product particles into a granulator, add 200g of coating layer material, and transfer in the granulator so that the fine particles are completely adhered to the surface of the coarse particles. At the same time, add 50g of quartz powder, and continue to transfer until the surface of the particles is smooth and the surface of the coarse particles is smooth. Then heat to 30°C and cure for 1h, and obtain a low-density proppant after screening.

[0088] The rotation speed of the granulator can be about 1800 rpm, and the coating layer material is coated on the surface of the particles.

[0089] The coating layer material is prepared by the following steps:

[0090] 1 kg of husk powder with a particle size of no more than 45 μm and 500 g of thermosetting phenolic resin with a solid content of 50% to 70% are mixed evenly and then soaked for 2 hours to obtain a coating material. The coating material is prepared in advance.

[0091] The parameters of the low-density proppant here include: bulk density of 0.89 g / cm 3 , apparent density is 1.15g / cm 3 , acid solubility is 3.4%, sphericity is 0.8, and 52MPa crushing rate is 8.0%.

[0092] Example 4

[0093] S210, weighing 1 kg of nut shell particles with a particle size range of 300 μm to 500 μm, and 300 g of a thermosetting phenolic resin with a solid content of 50% to 70% are mixed evenly, and the mixture is immersed and stirred until there is no obvious liquid on the surface to obtain the first semi-finished particles.

[0094] S220, transfer the first semi-finished product particles into a granulator, add 200g of coating layer material, and transfer in the granulator so that the fine particles are completely adhered to the surface of the coarse particles. At the same time, add 50g of active silicon powder, and continue to transfer until the surface of the particles is smooth and the surface of the coarse particles is smooth. Then heat to 100°C and cure for 2h, and obtain a low-density proppant after screening.

[0095] The rotation speed of the granulator can be about 1800 rpm, and the coating layer material is coated on the surface of the particles.

[0096] The coating layer material is prepared by the following steps:

[0097] Add 500g of thermosetting phenolic resin with a solid content of 50% to 70% to 1kg of husk powder with a particle size of no more than 45μm, mix well and soak for 2h for later use.

[0098] The parameters of the low-density proppant here include: bulk density of 0.95 g / cm 3 , apparent density is 1.25g / cm 3 , acid solubility is 1% to 4%, sphericity is 0.8, and 52MPa crushing rate is 6.5%.

[0099] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the embodiments of the present disclosure, but the embodiments of the present disclosure are not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the embodiments of the present disclosure, and these modifications and improvements are also considered to be within the protection scope of the embodiments of the present disclosure.

Claims

1. A method for preparing a low-density proppant, characterized in that: The method comprises: The nut shell particles with a particle size range of 106 μm to 710 μm and the thermosetting phenolic resin with a preset solid content are uniformly mixed in a mass ratio of 10: (2 to 5), and the mixture is immersed and stirred until there is no obvious liquid on the surface to obtain the first semi-finished particles; The first semi-finished product particles are transferred into a high-speed granulator, and wood powder or first nut shell powder having a mass ratio of (2-3): (60-75) to the first semi-finished product particles and a particle size of not more than 45 μm is added, and the particles are evenly dispersed and then heated and cured for 30 min-60 min to obtain second semi-finished product particles; The second semi-finished product particles are transferred into the high-speed granulator, a certain amount of binder is added, and the mixture is stirred evenly; a certain amount of second nut shell powder is added, and the mixture is stirred until the second nut shell powder is completely coated on the particles, and the rotation speed is reduced to a preset speed, and then a certain amount of powder is added, dispersed, and then the mixture is transferred into the low-speed granulator; wherein the mass ratio of the second semi-finished product particles, the binder, and the second nut shell powder is (125-155): (2-7): (10-40), and the mass ratio of the powder to the second nut shell powder is (1-2): 3; The particles are transferred in the low-speed granulator until the surface of the particles is smooth, and then cured at a preset temperature for a certain period of time, and a low-density proppant is obtained after screening; The binder is prepared by the following steps: Liquid bisphenol A epoxy resin and liquid modified diaminodiphenylmethane with a preset viscosity are uniformly mixed in a mass ratio of 100: (10-30) to obtain a binder.

2. The method according to claim 1, characterized in that: The preset rotation speed is 500 rpm to 1000 rpm.

3. The method according to claim 1 or 2, characterized in that: The parameters of the low-density proppant include: Bulk density range is 0.85g / cm 3 ~1.0g / cm 3 , apparent density range is 1.15 g / cm 3 ~1.35g / cm 3 , acid solubility range is 1%~4%, sphericity range is 0.7~0.9, and 52MPa crushing rate range is 4%~9%.

4. A method for preparing a low-density proppant, characterized in that: The method comprises: The nut shell particles with a particle size range of 106 μm to 710 μm and the thermosetting phenolic resin with a preset solid content are uniformly mixed in a mass ratio of 10: (2 to 5), and the mixture is immersed and stirred until there is no obvious liquid on the surface to obtain the first semi-finished particles; The first semi-finished product particles are transferred into a granulator, a certain amount of coating material is added, and the particles are transferred in the granulator until the fine particles are completely adhered to the surface of the coarse particles, and a certain amount of powder is added at the same time, and the particles are further transferred until the surface is smooth, and then cured at a preset temperature for a certain period of time, and a low-density proppant is obtained after screening; wherein the mass ratio of the first semi-finished product particles to the coating material is (12-15): (2-3), and the mass ratio of the powder to the coating material is 1: (4-6); The coating layer material is prepared by the following steps: The husk powder with a particle size of no more than 45 μm and the thermosetting phenolic resin with a solid content of 50% to 70% are mixed in a mass ratio of 2: (0.5 to 1.5), and then soaked for a certain period of time to obtain a coating layer material.

5. The method according to claim 4, characterized in that The parameters of the low-density proppant include: Bulk density range is 0.8g / cm 3 ~0.95g / cm 3 , apparent density range is 1.05 g / cm 3 ~1.25g / cm 3 , acid solubility range is 1%~4%, sphericity range is 0.7~0.85, and 52MPa crushing rate range is 6%~9%.

6. A low-density proppant, characterized in that: The method is prepared according to any one of claims 1 to 5.

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