A high temperature resin coated sand and a method of making the same

Abstract

The application relates to the technical field of sand prevention materials for oil and gas wells, in particular to high-temperature resin-coated sand and a preparation method thereof. The high-temperature resin-coated sand has a core-shell structure, the inner core is a framework particle, and the outer shell comprises, from inside to outside, a surface modification layer, a resin inner layer and a resin outer layer. The framework particle comprises a mixture of quartz sand with multiple particle sizes, and the average particle size of the framework particle is 0.3mm-1.8mm. The raw materials of the surface modification layer comprise inorganic nano-particles, a silane coupling agent and an acid solution. The raw materials of the resin inner layer comprise thermosetting phenolic resin and asbestos, and the raw materials of the resin outer layer comprise phenolic resin and a heat-resistant additive. By adding inorganic nano-particles and an acid solution into the silane coupling agent, limiting the average particle size of the framework particle, forming the surface modification layer, and then forming the resin inner layer comprising asbestos and the resin outer layer comprising the heat-resistant additive, the heat-resistant property of the high-temperature resin-coated sand under long-term high temperature can be improved by using the heat-resistant additive to improve the heat insulation of the resin outer layer.

Description

Technical Field

[0001] This application relates to the field of oil and gas well sand control materials, and in particular to a high-temperature resin-coated sand and its preparation method. Background Technology

[0002] Heavy oil thermal recovery wells commonly experience sand production during well extraction due to loosely cemented formation rocks and the high-temperature steam injection. To address this issue, resin-coated sand is typically used for fracturing and backfilling sand control, or artificial wellbore sand control. Resin-coated sand refers to a type of material that uses different framework particles and uniformly coats their outer surface with a cementable resin coating. Based on their temperature tolerance, resin-coated sand is generally classified into low-temperature resin-coated sand (30℃~60℃), normal-temperature resin-coated sand (60℃~120℃), and high-temperature resin-coated sand (120-350℃). Since the downhole temperature in heavy oil thermal recovery wells can generally reach 200℃~350℃, high-temperature resin-coated sand is typically used. Furthermore, resin-coated sand is a crucial technology for chemical sand control in oil and gas wells; therefore, its performance directly affects the effectiveness and duration of sand control.

[0003] However, high-temperature coated sand currently has the following problems:

[0004] (1) Poor temperature resistance. After high-temperature aging, the bonding strength of the resin-coated sand is greatly reduced. In field applications, it can generally only meet 2-3 steam huff and puff cycles, resulting in a short shelf life.

[0005] (2) The processing technology is complex, involving multiple processes, making it difficult to guarantee product quality and resulting in large processing losses;

[0006] (3) Some products are prone to clumping during storage and are not easy to preserve;

[0007] (4) Since the lubricant used to improve the fluidity of the coated sand and prevent it from clumping does not participate in the bonding reaction of the resin, it has a great influence on the bonding strength of the coated sand.

[0008] (5) High product cost: The cost of existing mature high-temperature resin coated sand on the market is relatively high, which limits the large-scale application of this product in oil fields.

[0009] The most important issue is that the high-temperature resin-coated sand currently has poor high-temperature resistance, resulting in low bonding strength and short shelf life. Therefore, improving the long-term high-temperature resistance of high-temperature resin-coated sand is a technical problem that urgently needs to be solved. Summary of the Invention

[0010] This application provides a high-temperature resin-coated sand and its preparation method to solve the technical problem of poor resistance of high-temperature resin-coated sand under long-term high-temperature conditions in the prior art.

[0011] In a first aspect, this application provides a high-temperature resin-coated sand, which has a core-shell structure, with the core being skeleton particles and the outer shell consisting of a surface modification layer, an inner resin layer, and an outer resin layer from the inside out.

[0012] The skeleton particles comprise a mixture of quartz sands of various particle sizes, with an average particle size of 0.3 mm to 1.8 mm.

[0013] The raw materials for the surface modification layer include inorganic nanoparticles and silane coupling agents;

[0014] The raw materials for the inner resin layer include thermosetting phenolic resin and asbestos, and the raw materials for the outer resin layer include phenolic resin and heat-resistant additives.

[0015] Optionally, the mass ratio of the skeleton particles, the surface modified layer, the inner resin layer, and the outer resin layer is 100:0.5-1.5:2-6:6-15.

[0016] Optionally, the silane coupling agent includes at least one of aminopropyltriethoxysilane, methyltriethoxysiloxane, and propyltrimethoxysilane.

[0017] Optionally, the quartz sand mixture includes quartz sand of a first particle size, quartz sand of a second particle size, and quartz sand of a third particle size;

[0018] The first-size quartz sand has a particle size of 30-50 mesh, the second-size quartz sand has a particle size of 20-40 mesh, and the third-size quartz sand has a particle size of 16-20 mesh.

[0019] Optionally, the mass ratio of the inorganic nanoparticles to the silane coupling agent is 1:0.2 to 1, wherein the inorganic nanoparticles are hydrophilic nano-silica with a particle size of 1 nm to 500 nm.

[0020] Optionally, the phenolic resin includes thermoplastic phenolic resin and / or thermosetting phenolic resin.

[0021] Optionally, when the phenolic resin is a thermoplastic phenolic resin, the raw material of the outer layer of the resin further includes a curing agent;

[0022] The weight ratio of the curing agent to the resin outer layer is 0.05 to 0.2.

[0023] The curing agent includes hexamethylenetetramine and / or paraformaldehyde.

[0024] Optionally, the heat-resistant additive includes at least one of mullite powder, titanium dioxide, carbon fiber powder, asphalt powder, graphite powder, dolomite powder, coke powder, and carbon black powder.

[0025] Optionally, when the heat-resistant additive includes mullite powder, carbon fiber powder and graphite powder, the mass ratio of the mullite powder, the carbon fiber powder and the graphite powder is 1:0.2-0.5:0.2-0.5.

[0026] Secondly, this application provides a method for preparing the high-temperature resin-coated sand described in the first aspect, the method comprising:

[0027] The skeleton particles are heated to a preset heating temperature and mixed, then cooled and coated with a surface treatment liquid to form a surface modification layer on the surface of the skeleton particles.

[0028] An inner resin solution is added to the skeleton particles that have formed the surface modified layer, and the mixture is stirred to form an inner resin layer.

[0029] An outer resin solution is added to the skeleton particles that form the inner resin layer, and the mixture is stirred to form the outer resin layer.

[0030] The skeletal particles that form the outer layer of the resin are stirred until they are evenly dispersed, resulting in high-temperature resin-coated sand.

[0031] Optionally, the preset heating temperature is 200℃~300℃.

[0032] Optionally, the final temperature of the cooling is 100°C to 150°C.

[0033] The technical solutions provided in this application have the following advantages compared with the prior art:

[0034] This application provides a high-temperature resin-coated sand. By adding inorganic nanoparticles and acid to a silane coupling agent, the inorganic nanoparticles are firmly adsorbed onto the surface of quartz stone under the binding of the silane coupling agent. At the same time, the average particle size of the framework particles is limited, which increases the surface roughness and specific surface area of ​​the quartz sand. Meanwhile, the acid can further promote the hydrolysis of the silane coupling agent, forming stronger covalent bonds with the quartz sand surface, thereby forming a surface modification layer. The surface modification layer improves the adhesion of the quartz sand to the inner and outer resin layers, and improves the high-temperature stability of the high-temperature resistant resin. Furthermore, the inner resin layer includes asbestos and the outer resin layer includes heat-resistant additives. The asbestos fibers improve the heat insulation effect of the inner resin layer, and the heat-resistant additives improve the heat resistance of the outer resin layer. Thus, the long-term high-temperature resistance of the high-temperature resin-coated sand is improved by adhering the inner and outer resin layers through the surface modification layer. Attached Figure Description

[0035] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of high-temperature resin-coated sand provided in the embodiments of this application, wherein 1-skeleton particles, 2-surface modification layer, 3-resin inner layer, and 4-resin outer layer;

[0038] Figure 2 A schematic diagram of the surface structure of the skeleton particles being quartz sand, provided in an embodiment of this application;

[0039] Figure 3 This is a microscopic schematic diagram of the surface atomic composition of high-temperature resin-coated sand provided in an embodiment of this application;

[0040] Figure 4 A schematic diagram of the preparation method of high-temperature resin-coated sand provided in the embodiments of this application;

[0041] Figure 5 This is a schematic diagram showing the compressive strength data of high-temperature resin-coated sand under different aging times, as provided in the embodiments of this application. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0044] The creative thinking behind this application is:

[0045] Current technologies related to high-temperature resin-coated sand include:

[0046] (1) A high-temperature self-curing proppant and its preparation method, wherein the coated sand uses quartz sand or ceramsite as the skeleton material, and epoxy resin, phenolic resin, hexamethylenetetramine, calcium / magnesium stearate, etc. as the coating material. Epoxy resin and phenolic resin are coated successively onto the skeleton material, and finally calcium / magnesium stearate is added to disperse the coated particles. After removing the agglomerated coated sand, the finished product is obtained. The processing technology of this coated sand is simple, and the preparation materials are widely available and reasonably priced. However, the skeleton strength and temperature resistance of the finished product are generally poor. It is prone to aging under high temperature conditions and cannot withstand the effects of multiple rounds of gas injection, which easily leads to a short sand-proofing period.

[0047] (2) A method for preparing high-temperature resistant multilayer coated sand, wherein the coated sand uses sieved and heated quartz sand or ceramsite as the skeleton material, and modified phenolic resin, unsaturated resin, organosilicon, hexamethylenetetramine, calcium stearate, etc. as coating materials, and is made into a finished product through a three-stage coating process. After aging at 300℃ for 24 hours, the coated sand still has a strength of 7.1 MPa and a permeability of 87 μm. 2 It exhibits superior performance compared to conventional coated sand, and is easier to store and transport, and less prone to clumping. However, the processing technology for this coated sand is relatively complex, involving multiple stages of processing, and its anti-aging properties under operating conditions above 300℃ still need to be verified.

[0048] (3) A high-temperature resistant resin-coated sand made from nutshell particles and its preparation method. This coated sand uses nutshell particles as the core support material and thermosetting phenolic resin, furan resin, ethanol, etc. as coating materials. After stirring, drying, crushing, sieving and other processes, it is made into a finished product. The density of this coated sand is lower than that of conventional coated sand, which is conducive to the carrying liquid of sand. After the rock core is solidified, under the working conditions of 350℃ and ring pressure of 10-15MPa, its strength can still reach more than 10MPa and the permeability is 20μm. 2 The above can meet the sand control requirements of steam injection or steam-driven oil wells; however, the coated sand has fruit shell particles as its core and is an organic material. It can withstand short-term high-temperature environments, but carbonization occurs in long-term high-temperature environments, resulting in a sharp decrease in strength, making it difficult to promote in practical applications.

[0049] (4) A thermosetting resin-coated sand based on heavy metal minerals and its preparation method. The coated sand uses heavy metal minerals containing copper oxide and silicon carbide as the skeleton material, and organosilicon-modified phenolic resin, thermosetting furan resin, KH-550, coal tar, graphite powder, etc. as coating materials. After stirring, drying, pulverizing and other processes, the finished product is produced. After solidification, the core of the coated sand can achieve a strength of more than 6 MPa and can withstand the erosion of alkaline steam at 350℃, which can meet the sand control requirements of steam injection or steam-driven oil wells. However, the cost of this coated sand is relatively high, and its strength is greatly affected by the acidic environment, thus limiting its application.

[0050] In summary, existing high-temperature resin-coated sands mainly have the following problems:

[0051] (1) Poor temperature resistance. After high-temperature aging, the bonding strength of the resin-coated sand is greatly reduced. In field applications, it can generally only meet 2-3 steam huff and puff cycles, resulting in a short shelf life.

[0052] (2) The processing technology is complex, involving multiple processes, making it difficult to guarantee product quality and resulting in large processing losses;

[0053] (3) Some products are prone to clumping during storage and are not easy to preserve;

[0054] (4) Since the lubricant used to improve the fluidity of the coated sand and prevent it from clumping does not participate in the bonding reaction of the resin, it has a great influence on the bonding strength of the coated sand.

[0055] (5) High product cost: The cost of existing mature high-temperature resin coated sand on the market is relatively high, which limits the large-scale application of this product in oil fields.

[0056] When high-temperature resin-coated sand uses quartz sand as the framework particle, its smooth surface and predominantly inert silicon atoms result in weak bonding with the resin, leading to easy desorption under high-temperature conditions. Although silane coupling agents are commonly used to enhance the bonding between the resin and quartz sand, desorption still occurs under prolonged high-temperature conditions. Therefore, improving the long-term stability of high-temperature resin-coated sand at high temperatures is a pressing technical problem that needs to be solved.

[0057] like Figure 1 , Figure 2 and Figure 3 As shown, this application embodiment provides a high-temperature resin-coated sand, which has a core-shell structure, with the core being skeleton particles and the outer shell consisting of a surface modification layer, an inner resin layer, and an outer resin layer from the inside out.

[0058] The skeleton particles comprise a mixture of quartz sands of various particle sizes, with an average particle size of 0.3 mm to 1.8 mm.

[0059] The raw materials for the surface modification layer include inorganic nanoparticles and silane coupling agents;

[0060] The raw materials for the inner resin layer include thermosetting phenolic resin and asbestos, and the raw materials for the outer resin layer include phenolic resin and heat-resistant additives.

[0061] In this embodiment of the application, the positive effect of limiting the average particle size of the skeleton particles to 0.3 mm to 1.8 mm is that within this average particle size range, the quartz sand acting as the skeleton particles has sufficient specific surface area and roughness, thereby enabling the resin inner layer to adhere firmly to the surface of the quartz sand, and thus improving the high-temperature resistance of the high-temperature resin-coated sand.

[0062] The asbestos described in this application is generally made of asbestos fibers with a length of 0.01 mm to 0.1 mm;

[0063] The thermosetting phenolic resin is a liquid thermosetting resin with a solid content of ≥60%.

[0064] The phenolic resin generally includes thermoplastic phenolic resin and thermosetting phenolic resin, and the phenolic resin is generally in solid powder form with a particle size of 200-300 mesh and a softening point ≤120℃.

[0065] The heat-resistant additives generally refer to powder materials with high-temperature resistance properties, and their particle size is 150 mesh to 400 mesh.

[0066] The mass ratio of the thermosetting phenolic resin to the asbestos is 1:0.1 to 0.5, and the asbestos is dispersed in alcohol before being added to the thermosetting phenolic resin.

[0067] In some optional embodiments, the mass ratio of the skeleton particles, the surface-modified layer, the inner resin layer, and the outer resin layer is 100:0.5-1.5:2-6:6-15.

[0068] In this embodiment of the application, limiting the mass ratio of the skeleton particles, the surface modification layer, the inner resin layer, and the outer resin layer to 100:0.5 to 1.5:2 to 6:6 to 15 has the positive effect that within this mass ratio range, the surface modification layer and the skeleton particles are firmly bonded together, while ensuring that the inner resin layer and the outer resin layer are firmly bonded to the surface modification layer in sequence. This ensures the stability of the high-temperature resin-coated sand under long-term high-temperature conditions and improves the high-temperature resistance of the high-temperature resin-coated sand.

[0069] In some optional embodiments, the silane coupling agent includes at least one of aminopropyltriethoxysilane, methyltriethoxysiloxane, and propyltrimethoxysilane; and when the silane coupling agent is a mixture of multiple substances, the proportions are arbitrary.

[0070] In this embodiment, the specific type of silane coupling agent is specified, which enables inorganic nanoparticles to fully adhere to the surface of the framework particles through the action of the silane coupling agent, thereby effectively increasing the roughness and specific surface area of ​​the framework particles.

[0071] In some alternative embodiments, the quartz sand mixture comprises quartz sand of a first particle size, quartz sand of a second particle size, and quartz sand of a third particle size;

[0072] The first-size quartz sand has a particle size of 30-50 mesh, the second-size quartz sand has a particle size of 20-40 mesh, and the third-size quartz sand has a particle size of 16-20 mesh.

[0073] In this embodiment of the application, the specific particle size distribution of the quartz sand mixture is defined, which can effectively cover quartz sand of different particle sizes. At the same time, the three particle sizes of quartz sand can complement each other through particle size complementarity, thereby making the particles of the high-temperature resin coated sand uniform and ensuring the performance of the high-temperature resin coated sand.

[0074] In some optional embodiments, the mass ratio of the inorganic nanoparticles to the silane coupling agent is 1:0.2 to 1, wherein the inorganic nanoparticles are hydrophilic nano-silica with a particle size of 1 nm to 500 nm.

[0075] In this embodiment, the inorganic nanoparticles are limited to hydrophilic nano-silica. The positive effect of limiting the mass ratio of inorganic nanoparticles to silane coupling agent to 1:0.2 to 1 is that within this mass ratio range, the hydrophilic nano-silica can be ensured to adhere to the surface of the skeleton particles through the action of the silane coupling agent, thereby increasing the roughness and specific surface area of ​​the skeleton particles, thereby increasing the adhesion of the resin inner layer, and thus improving the stability of the overall high-temperature resin-coated sand under long-term high-temperature conditions.

[0076] Since hydrophilic nano-silica is currently the most widely used inorganic nanoparticle material, and its cost is low, it can also effectively reduce the cost of high-temperature resin-coated sand.

[0077] In some alternative embodiments, the phenolic resin includes thermoplastic phenolic resin and / or thermosetting phenolic resin.

[0078] In the embodiments of this application, the specific classification of phenolic resins is defined, which can cover most of the resin materials used in high-temperature resin-coated sand, thereby improving the applicability of this application.

[0079] In some optional embodiments, when the phenolic resin is a thermoplastic phenolic resin, the raw material of the outer layer of the resin further includes a curing agent;

[0080] The weight ratio of the curing agent to the resin outer layer is 0.05 to 0.2.

[0081] The curing agent includes hexamethylenetetramine and / or paraformaldehyde, and when the curing agent is a mixture of multiple substances, the proportions are arbitrary.

[0082] In this embodiment, the amount of curing agent added to the outer resin layer is limited, and the type of curing agent is also limited. When thermoplastic phenolic resin is used in the outer resin layer, the curing agent can ensure that the thermoplastic phenolic resin and the heat-resistant additives are fully combined, thereby ensuring the molding of the outer resin layer and improving the overall high-temperature resistance of the high-temperature resin-coated sand.

[0083] In some alternative embodiments, the heat-resistant additive includes at least one of mullite powder, titanium dioxide, carbon fiber powder, asphalt powder, graphite powder, dolomite powder, coke powder, and carbon black powder.

[0084] In this application embodiment, the specific types of heat-resistant additives are limited. By limiting the types of heat-resistant additives, the heat resistance of the resin outer layer can be effectively improved. At the same time, the wide range of heat-resistant additives used can improve the applicability of this application.

[0085] In some optional embodiments, when the heat-resistant additive includes mullite powder, carbon fiber powder and graphite powder, the mass ratio of the mullite powder, the carbon fiber powder and the graphite powder is 1:0.2-0.5:0.2-0.5.

[0086] In this embodiment of the application, limiting the mass ratio of mullite powder, carbon fiber powder and graphite powder to 1:0.2-0.5:0.2-0.5 has the positive effect that within this mass ratio range, the temperature resistance of the heat-resistant additive can be comprehensively improved, so that the high-temperature resin-coated sand can meet the temperature requirements of heavy oil thermal recovery wells.

[0087] like Figure 4 As shown, based on a general inventive concept, this application provides a method for preparing the high-temperature resin-coated sand, the method comprising:

[0088] S1. Heat the skeleton particles to a preset heating temperature and mix them, then cool and spray with a surface treatment liquid to form a surface modification layer on the surface of the skeleton particles;

[0089] S2. Add an inner layer resin solution to the skeleton particles that have formed the surface modified layer, and stir to form a resin inner layer;

[0090] S3. Add an outer resin solution to the skeleton particles that have formed the inner resin layer, and stir to form an outer resin layer;

[0091] S4. Stirring the skeletal particles that form the outer layer of resin until they are evenly dispersed, to obtain high-temperature resin-coated sand.

[0092] In this embodiment, by first heating the skeleton particles to a set temperature, then cooling them and spraying a surface treatment liquid, the surfaces of quartz sand with different particle sizes in the skeleton particles can better combine with the surface treatment liquid to form a surface modification layer. Then, a resin inner layer and a resin outer layer are generated sequentially on the surface modification layer, thereby completing the preparation of high-temperature resin-coated sand.

[0093] This method is for the high-temperature resin coated sand mentioned above. The specific composition and structure of the high-temperature resin coated sand can be referred to the above embodiments. Since this method adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0094] In some optional embodiments, the preset heating temperature is 200°C to 300°C.

[0095] In this embodiment of the application, the positive effect of limiting the preset heating temperature to 200℃~300℃ is that within this temperature range, the dust impurities adsorbed on the surface of the quartz sand can be thermally desorbed, which is beneficial to the adsorption strength of the surface modification layer and the inner resin layer.

[0096] In some alternative embodiments, the final temperature of the cooling is 100°C to 150°C.

[0097] In this embodiment of the application, the positive effect of limiting the final cooling temperature to 100°C to 150°C is that within this temperature range, the reactivity of the coupling agent can be stimulated, allowing the coupling agent and nano-silica to be more firmly adsorbed, and accelerating the evaporation of alcohol and water, which is beneficial to the adsorption of the inner layer of the resin.

[0098] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0099] Example 1

[0100] Take 10g of industrial alcohol (95% by mass) and 3g of water and mix them evenly. Add 0.1g of coupling agent KH550 (aminopropyltriethoxysilane) and 0.1g of hydrophilic nano-SiO2. After stirring, place it in an ultrasonic vibrator for 10min to 20min. Finally, add acetic acid and adjust the pH to 2 to 3 to prepare a quartz sand surface treatment solution for later use.

[0101] Take 0.3g of asbestos fiber powder and add it to 0.6g of industrial alcohol. After stirring evenly, add it to 0.8g of liquid thermosetting phenolic resin and stir evenly to disperse the asbestos fiber powder evenly in the thermosetting phenolic resin. Prepare the inner layer mixed resin liquid for later use.

[0102] Take 1.8g of powdered thermosetting phenolic resin, add 0.4g of mullite powder, 0.1g of carbon fiber powder and 0.1g of graphite powder in sequence, mix evenly to prepare an outer layer mixed resin for later use.

[0103] Take 20g of quartz sand with a particle size of 20-40 mesh, place it in an oven and heat to 200℃. Remove and cool to about 120℃. While continuously stirring, spray the quartz sand surface treatment liquid onto the quartz sand surface and continue stirring for 10 minutes to allow the alcohol and water on the quartz sand surface to evaporate completely. Then, while continuously stirring, add the inner layer mixed resin liquid and continue stirring for 10 minutes to evenly coat the quartz sand surface with liquid thermosetting phenolic resin. Next, while continuously stirring, add the outer layer mixed resin and continue stirring for 10 minutes to evenly coat the outermost layer of quartz sand with solid phenolic resin. Continue stirring until the quartz sand particles are completely dispersed to obtain high-temperature resin-coated sand.

[0104] The liquid thermosetting phenolic resin was purchased from Jining Baichuan Chemical Co., Ltd., grade 2127; the solid powder thermosetting phenolic resin was purchased from Tianyu High Temperature Resin Materials Co., Ltd.; the other materials are all general-purpose products and can be purchased from different manufacturers in the market.

[0105] Example 2

[0106] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is as follows:

[0107] Take 10g of industrial alcohol (95% by mass) and 3g of water and mix them evenly. Add 0.1g of coupling agent KH550 (aminopropyltriethoxysilane) and 0.1g of hydrophilic nano-SiO2. After stirring, place it in an ultrasonic vibrator for 10min to 20min. Finally, add acetic acid and adjust the pH to 2 to 3 to prepare a quartz sand surface treatment solution for later use.

[0108] Take 0.15g of asbestos fiber powder and add it to 0.6g of industrial alcohol. After stirring evenly, add it to 0.4g of liquid thermosetting phenolic resin and stir evenly to disperse the asbestos fiber powder evenly in the thermosetting phenolic resin. Prepare the inner layer mixed resin liquid for later use.

[0109] Take 0.9g of powdered thermosetting phenolic resin, add 0.2g of mullite powder, 0.05g of carbon fiber powder and 0.05g of graphite powder in sequence, mix evenly to prepare an outer layer mixed resin for later use.

[0110] Take 20g of quartz sand with a particle size of 20-40 mesh, place it in an oven and heat to 200℃. Remove and cool to about 120℃. While continuously stirring, spray the quartz sand surface treatment liquid onto the quartz sand surface and continue stirring for 10 minutes to allow the alcohol and water on the quartz sand surface to evaporate completely. Then, while continuously stirring, add the inner layer mixed resin liquid and continue stirring for 10 minutes to evenly coat the quartz sand surface with liquid thermosetting phenolic resin. Next, while continuously stirring, add the outer layer mixed resin and continue stirring for 10 minutes to evenly coat the outermost layer of quartz sand with solid phenolic resin. Continue stirring until the quartz sand particles are completely dispersed to obtain high-temperature resin-coated sand.

[0111] The liquid thermosetting phenolic resin was purchased from Jining Baichuan Chemical Co., Ltd., grade 2127; the solid powder thermosetting phenolic resin was purchased from Tianyu High Temperature Resin Materials Co., Ltd.; the other materials are all general-purpose products and can be purchased from different manufacturers in the market.

[0112] Example 3

[0113] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is as follows:

[0114] Take 10g of industrial alcohol (95% by mass) and 3g of water and mix them evenly. Add 0.1g of coupling agent KH550 (aminopropyltriethoxysilane) and 0.1g of hydrophilic nano-SiO2. After stirring, place it in an ultrasonic vibrator for 10min to 20min. Finally, add acetic acid and adjust the pH to 2 to 3 to prepare a quartz sand surface treatment solution for later use.

[0115] Take 0.2g of asbestos fiber powder and add it to 0.6g of industrial alcohol. After stirring evenly, add it to 0.6g of liquid thermosetting phenolic resin and stir evenly to disperse the asbestos fiber powder evenly in the thermosetting phenolic resin. Prepare the inner layer mixed resin liquid for later use.

[0116] Take 1.2g of powdered thermosetting phenolic resin, add 0.27g of mullite powder, 0.07g of carbon fiber powder and 0.07g of graphite powder in sequence and mix evenly to prepare an outer layer mixed resin for later use.

[0117] Take 20g of quartz sand with a particle size of 20-40 mesh, place it in an oven and heat to 200℃. Remove and cool to about 120℃. While continuously stirring, spray the quartz sand surface treatment liquid onto the quartz sand surface and continue stirring for 10 minutes to allow the alcohol and water on the quartz sand surface to evaporate completely. Then, while continuously stirring, add the inner layer mixed resin liquid and continue stirring for 10 minutes to evenly coat the quartz sand surface with liquid thermosetting phenolic resin. Next, while continuously stirring, add the outer layer mixed resin and continue stirring for 10 minutes to evenly coat the outermost layer of quartz sand with solid phenolic resin. Continue stirring until the quartz sand particles are completely dispersed to obtain high-temperature resin-coated sand.

[0118] The liquid thermosetting phenolic resin was purchased from Jining Baichuan Chemical Co., Ltd., grade 2127; the solid powder thermosetting phenolic resin was purchased from Tianyu High Temperature Resin Materials Co., Ltd.; the other materials are all general-purpose products and can be purchased from different manufacturers in the market.

[0119] Example 4

[0120] Comparing Example 4 with Example 1, the difference between Example 4 and Example 1 is as follows:

[0121] Take 10g of industrial alcohol (95% by mass) and 3g of water and mix them evenly. Add 0.3g of coupling agent KH550 (aminopropyltriethoxysilane) and 0.3g of hydrophilic nano-SiO2. After stirring, place it in an ultrasonic vibrator for 10min to 20min. Finally, add acetic acid and adjust the pH to 2 to 3 to prepare a quartz sand surface treatment solution for later use.

[0122] Take 0.3g of asbestos fiber powder and add it to 0.6g of industrial alcohol. After stirring evenly, add it to 0.8g of liquid thermosetting phenolic resin and stir evenly to disperse the asbestos fiber powder evenly in the thermosetting phenolic resin. Prepare the inner layer mixed resin liquid for later use.

[0123] Take 1.8g of powdered thermoplastic phenolic resin, and add 0.2g of hexamethylenetetramine, 0.6g of mullite powder, 0.1g of carbon fiber powder and 0.2g of graphite powder in sequence. Mix them evenly to prepare an outer layer mixed resin for later use.

[0124] Take 20g of quartz sand with a particle size of 20-40 mesh, place it in an oven and heat to 200℃. Remove and cool to about 120℃. While continuously stirring, spray the quartz sand surface treatment liquid onto the quartz sand surface and continue stirring for 10 minutes to allow the alcohol and water on the quartz sand surface to evaporate completely. Then, while continuously stirring, add the inner layer mixed resin liquid and continue stirring for 10 minutes to evenly coat the quartz sand surface with liquid thermosetting phenolic resin. Next, while continuously stirring, add the outer layer mixed resin and continue stirring for 10 minutes to evenly coat the outermost layer of quartz sand with solid phenolic resin. Continue stirring until the quartz sand particles are completely dispersed to obtain high-temperature resin-coated sand.

[0125] The liquid thermosetting phenolic resin was purchased from Jining Baichuan Chemical Co., Ltd., grade 2127; the solid powder thermoplastic phenolic resin was purchased from Henan Zhongfan Dongsheng Chemical Co., Ltd., grade 2123; the other materials are all general-purpose products and can be purchased from different manufacturers in the market.

[0126] Comparative Example 1

[0127] Comparative Example 1 and Example 1 will be compared. The difference between Comparative Example 1 and Example 1 is as follows:

[0128] Take 0.3g of asbestos fiber powder and add it to 0.6g of industrial alcohol. After stirring evenly, add it to 0.8g of liquid thermosetting phenolic resin and stir evenly to disperse the asbestos fiber powder evenly in the thermosetting phenolic resin. Prepare the inner layer mixed resin liquid for later use.

[0129] Take 1.8g of powdered thermosetting phenolic resin, add 0.4g of mullite powder, 0.1g of carbon fiber powder and 0.1g of graphite powder in sequence, mix evenly to prepare an outer layer mixed resin for later use.

[0130] Take 20g of quartz sand with a particle size of 20-40 mesh, place it in an oven and heat to 200℃. Remove and cool to about 120℃. While continuously stirring, spray the quartz sand surface treatment liquid onto the quartz sand surface and continue stirring for 10 minutes to allow the alcohol and water on the quartz sand surface to evaporate completely. Then, while continuously stirring, add the inner layer mixed resin liquid and continue stirring for 10 minutes to evenly coat the quartz sand surface with liquid thermosetting phenolic resin. Next, while continuously stirring, add the outer layer mixed resin and continue stirring for 10 minutes to evenly coat the outermost layer of quartz sand with solid phenolic resin. Continue stirring until the quartz sand particles are completely dispersed to obtain high-temperature resin-coated sand.

[0131] Comparative Example 2

[0132] Comparative Example 2 and Example 1 will be compared. The difference between Comparative Example 2 and Example 1 is as follows:

[0133] Take 10g of industrial alcohol (95% by mass) and 3g of water and mix them evenly. Add 0.3g of coupling agent KH550 (aminopropyltriethoxysilane) and 0.3g of hydrophilic nano-SiO2. After stirring, place it in an ultrasonic vibrator for 10min to 20min. Finally, add acetic acid and adjust the pH to 2 to 3 to prepare a quartz sand surface treatment solution for later use.

[0134] Take 0.8g of liquid thermosetting phenolic resin and add it to 0.6g of industrial alcohol. Stir well to prepare an inner layer mixed resin liquid that does not contain asbestos fibers.

[0135] Take 1.8g of powdered thermosetting phenolic resin, add 0.4g of mullite powder, 0.1g of carbon fiber powder and 0.1g of graphite powder in sequence, mix evenly to prepare an outer layer mixed resin for later use.

[0136] Take 20g of quartz sand with a particle size of 20-40 mesh, place it in an oven and heat to 200℃. Remove and cool to about 120℃. While continuously stirring, spray the quartz sand surface treatment liquid onto the quartz sand surface and continue stirring for 10 minutes to allow the alcohol and water on the quartz sand surface to evaporate completely. Then, while continuously stirring, add the inner layer mixed resin liquid and continue stirring for 10 minutes to evenly coat the quartz sand surface with liquid thermosetting phenolic resin. Next, while continuously stirring, add the outer layer mixed resin and continue stirring for 10 minutes to evenly coat the outermost layer of quartz sand with solid phenolic resin. Continue stirring until the quartz sand particles are completely dispersed to obtain high-temperature resin-coated sand.

[0137] Comparative Example 3

[0138] Comparative Example 3 and Example 1 will be compared. The difference between Comparative Example 3 and Example 1 is as follows:

[0139] Take 10g of industrial alcohol (95% by mass) and 3g of water and mix them evenly. Add 0.3g of coupling agent KH550 (aminopropyltriethoxysilane) and 0.3g of hydrophilic nano-SiO2. After stirring, place it in an ultrasonic vibrator for 10min to 20min. Finally, add acetic acid and adjust the pH to 2 to 3 to prepare a quartz sand surface treatment solution for later use.

[0140] Take 0.3g of asbestos fiber powder and add it to 0.6g of industrial alcohol. After stirring evenly, add it to 0.8g of liquid thermosetting phenolic resin and stir evenly to disperse the asbestos fiber powder evenly in the thermosetting phenolic resin. Prepare the inner layer mixed resin liquid for later use.

[0141] Take 1.8g of powdered thermosetting phenolic resin as the outer layer mixed resin for later use.

[0142] Take 50g of quartz sand with a particle size of 20-40 mesh, place it in an oven and heat to 200℃. Remove and cool to about 120℃. While continuously stirring, spray the quartz sand surface treatment liquid onto the quartz sand surface and continue stirring for 10 minutes to allow the alcohol and water on the quartz sand surface to evaporate completely. Then, while continuously stirring, add the inner layer mixed resin liquid and continue stirring for 10 minutes to evenly coat the quartz sand surface with liquid thermosetting phenolic resin. Next, while continuously stirring, add the outer layer mixed resin and continue stirring for 10 minutes to evenly coat the outermost layer of quartz sand with solid phenolic resin. Continue stirring until the quartz sand particles are completely dispersed to obtain high-temperature resin-coated sand.

[0143] Relevant experimental and effect data:

[0144] 1. Performance testing was performed on the product obtained in Example 1, and the specific method is as follows:

[0145] Experimental conditions: Φ25mm×50mm glass tube, high-temperature oven, permeability tester, material mechanics testing machine, high-temperature aging tank.

[0146] Experimental method: (1) Take 20g of high-temperature resin-coated sand and put it into a Φ25×50mm glass tube. Press the two ends with metal mesh and fix it with a clamp to keep the coated sand in a compacted state. Put it in a high-temperature oven and set the temperature to 120℃ for pre-curing for 6h. Take it out, break the glass tube, and obtain the pre-cured rock core. Prepare 8 pre-cured rock cores of the same specifications in the same way.

[0147] (2) Place the pre-cured core into a high-temperature aging tank and add a certain amount of alkali solution until the pH is 8 to 9.

[0148] (3) Seal the high-temperature aging tank and place it in a high-temperature oven. Set the temperature to 320℃. Take out the aged core every two days.

[0149] (4) The permeability of the aged core was tested according to the method of SY / T 5276-2000 "Test Method for Flexural Strength, Compressive Strength and Permeability of Chemical Sand Control Artificial Core".

[0150] (5) The compressive strength of the aged core was tested according to the method specified in SY / T 5276-2000 "Test Methods for Flexural Strength, Compressive Strength and Permeability of Chemical Sand Control Artificial Core". The experimental results are as follows: Figure 5 As shown.

[0151] 2. Performance testing was performed on the product obtained in Example 1, using the following specific methods:

[0152] The performance of the high-temperature resin-coated sands obtained in Examples 1, 2, 1, 2, and 3 was tested using the following methods:

[0153] Experimental conditions: Φ25mm×50mm glass tube, high-temperature oven, permeability tester, material mechanics testing machine, high-temperature aging tank.

[0154] Experimental method: (1) Take 20g of high temperature resin coated sand and put it into a Φ25×50mm glass tube. Press the two ends with metal mesh and fix them with clamps to keep the coated sand in a compacted state. Place it in a high temperature oven, set the temperature to 120℃, and pre-cur it for 6 hours. Take it out, break the glass tube, and obtain the pre-cured rock core. Prepare 8 pre-cured rock cores of the same specifications in the same way.

[0155] (2) Place the pre-cured core into a high-temperature aging tank and add a certain amount of alkali solution until the pH is 8 to 9.

[0156] (3) Seal the high-temperature aging tank and place it in a high-temperature oven. Set the temperature to 320℃ and age it for 10 days. Then take out the aged core.

[0157] (4) The permeability of the aged core was tested according to the method of SY / T 5276-2000 "Test Method for Flexural Strength, Compressive Strength and Permeability of Chemical Sand Control Artificial Core".

[0158] (5) The compressive strength of the aged core was tested according to the method of SY / T 5276-2000 "Test Method for Flexural Strength, Compressive Strength and Permeability of Chemical Sand Control Artificial Core". The experimental results are shown in Table 1.

[0159] Table 1. Experimental test results of high-temperature resin-coated sand obtained in each embodiment and comparative example.

[0160]

[0161] Depend on Figure 5 From the data in Table 1, we can see that:

[0162] Permeability refers to the permeability of a core sample formed from a high-temperature resin-coated sand material after aging. The lower the permeability, the better the stability of the high-temperature resin-coated sand material.

[0163] Compressive strength refers to the compressive strength of the core material formed by the high-temperature resin-coated sand material after aging. The greater the compressive strength, the better the stability of the high-temperature resin-coated sand material.

[0164] As can be seen from the data in Examples 1-2:

[0165] If the high-temperature resin-coated sand material of this application is used, by adding inorganic nanoparticles and acid to the silane coupling agent and limiting the average particle size of the skeleton particles, the surface roughness and specific surface area of ​​the quartz sand are increased. At the same time, the acid can further promote the hydrolysis of the silane coupling agent to form a surface modification layer. Then, through the resin inner layer including asbestos and the resin outer layer including heat-resistant additives, and by using heat-resistant additives to improve the heat insulation effect of the resin outer layer, the resin inner layer and the resin outer layer are adhered through the surface modification layer, thereby improving the long-term high temperature resistance of the high-temperature resin-coated sand.

[0166] As can be seen from the data of Comparative Examples 1-3, if the structure of the high-temperature resin coating material as defined in this application is not adopted, or if the material as defined in this application is not adopted, the permeability and compressive strength of the obtained high-temperature resin coated sand material do not meet expectations.

[0167] One or more technical solutions in the embodiments of this application have at least the following technical effects or advantages:

[0168] (1) The high-temperature resin-coated sand provided in this application is characterized by a temperature resistance of only about 250°C for conventional high-temperature resin-coated sand, which cannot meet the temperature resistance requirements of more than 300°C for heavy oil thermal recovery wells. Therefore, this application adds asbestos fiber material to liquid thermosetting phenolic resin, and improves the temperature resistance of the inner layer of phenolic resin by utilizing the reinforcing and heat insulation effects of asbestos fiber on thermosetting phenolic resin. At the same time, heat-resistant additives are added to solid thermoplastic phenolic resin, and improve the temperature resistance of the outer layer of phenolic resin by utilizing the reinforcing and heat insulation effects of heat-resistant additives on thermoplastic phenolic resin.

[0169] (2) The high-temperature resin-coated sand provided in this application uses solid powdered phenolic resin to coat the surface of liquid thermosetting phenolic resin, which plays a role in isolation and lubrication, improves the fluidity of the coated sand, and prevents it from clumping during storage; at the same time, the solid powdered phenolic resin can be cemented and cured under high temperature steam, avoiding the influence of calcium stearate lubricant on the solidification strength of the coated sand in the prior art.

[0170] (3) The method for preparing high-temperature resin-coated sand provided in this application embodiment has a simple processing technology. Different materials are added in batches during continuous stirring to produce high-quality high-temperature coated sand. Compared with the existing product processing technology, the drying, crushing and screening steps are eliminated, and the material damage caused in the processing steps is greatly reduced.

[0171] (4) The method for preparing high-temperature resin-coated sand provided in this application embodiment, compared with the prior art which uses ceramsite, walnut shells and heavy metal minerals as skeleton particles, uses inexpensive quartz sand as skeleton particles and simplifies the processing steps. While improving the performance of the coated sand, it reduces the cost of high-temperature coated sand, which is conducive to the promotion and application of the technology.

[0172] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0173] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the orientation shown in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to."

[0174] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any actual relationship or order between these entities or operations. In this document, "and / or" describes the association between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0175] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A high-temperature resin-coated sand, characterized in that, The high-temperature resin-coated sand has a core-shell structure, with the core being skeleton particles and the outer shell consisting of a surface modification layer, an inner resin layer, and an outer resin layer from the inside out. The skeleton particles comprise a mixture of quartz sands of various particle sizes, with an average particle size of 0.3 mm to 1.8 mm. The raw materials for the surface modification layer include inorganic nanoparticles, silane coupling agents, and acid solutions; The raw materials for the inner resin layer include thermosetting phenolic resin and asbestos, and the raw materials for the outer resin layer include phenolic resin and heat-resistant additives. The inorganic nanoparticles are hydrophilic nano-silica, and the heat-resistant additives include at least one of mullite powder, titanium dioxide, carbon fiber powder, asphalt powder, graphite powder, dolomite powder, coke powder, and carbon black powder.

2. The high-temperature resin-coated sand according to claim 1, characterized in that, The mass ratio of the skeleton particles, the surface modified layer, the inner resin layer, and the outer resin layer is 100:0.5-1.5:2-6:6-15.

3. The high-temperature resin-coated sand according to claim 1, characterized in that, The silane coupling agent includes at least one of aminopropyltriethoxysilane, methyltriethoxysiloxane, and propyltrimethoxysilane.

4. The high-temperature resin-coated sand according to claim 1, characterized in that, The quartz sand mixture includes quartz sand of a first particle size, quartz sand of a second particle size, and quartz sand of a third particle size; The first-size quartz sand has a particle size of 30-50 mesh, the second-size quartz sand has a particle size of 20-40 mesh, and the third-size quartz sand has a particle size of 16-20 mesh.

5. The high-temperature resin-coated sand according to claim 1, characterized in that, The mass ratio of the inorganic nanoparticles to the silane coupling agent is 1:0.2 to 1, wherein the particle size of the hydrophilic nano-silica is 1 nm to 500 nm.

6. The high-temperature resin-coated sand according to claim 1, characterized in that, The phenolic resin includes thermoplastic phenolic resin and / or thermosetting phenolic resin.

7. The high-temperature resin-coated sand according to claim 6, characterized in that, When the phenolic resin is a thermoplastic phenolic resin, the raw material of the outer layer of the resin also includes a curing agent; The weight ratio of the curing agent to the resin outer layer is 0.05 to 0.

2. The curing agent includes hexamethylenetetramine and / or paraformaldehyde.

8. The high-temperature resin-coated sand according to claim 1, characterized in that, When the heat-resistant additive includes mullite powder, carbon fiber powder and graphite powder, the mass ratio of the mullite powder, the carbon fiber powder and the graphite powder is 1:0.2~0.5:0.2~0.

5.

9. A method for preparing high-temperature resin-coated sand as described in any one of claims 1-8, characterized in that, The method includes: The skeleton particles are heated to a preset heating temperature and mixed, then cooled and coated with a surface treatment liquid to form a surface modification layer on the surface of the skeleton particles. An inner resin solution is added to the skeleton particles that have formed the surface modified layer, and the mixture is stirred to form an inner resin layer. An outer resin solution is added to the skeleton particles that form the inner resin layer, and the mixture is stirred to form the outer resin layer. The skeletal particles that form the outer layer of the resin are stirred until they are evenly dispersed, resulting in high-temperature resin-coated sand.

10. The method according to claim 9, characterized in that, The preset heating temperature is 200℃~300℃.

11. The method according to claim 9, characterized in that, The final temperature of the cooling process is 100℃~150℃.

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