Low-temperature self-polymerization curing sand prevention proppant as well as preparation method and application thereof

Abstract

The invention provides a low-temperature self-polymerization curing sand prevention proppant as well as a preparation method and application thereof. The low-temperature self-polymerization curing sand prevention proppant is prepared from the following components in parts by weight: 100 to 150 parts of quartz sand, 7 to 9 parts of epoxy resin, 5 to 8 parts of diluent, 0.8 to 1.2 parts of curing agent, 0.5 to 0.7 part of coupling agent, 1.7 to 1.9 parts of flexibilizer, 0.8 to 1.2 parts of encapsulating agent and 0.9 to 1.1 parts of nano particles. Wherein the curing agent is a polyurethane material. The low-temperature self-polymerization curing sand prevention proppant has the advantages of low-temperature (20-50 DEG C) solidification performance, higher bonding strength, stable chemical property, enhanced acid and alkali resistance, better adaptability with bottom fluid and wide industrial application prospect.

Description

Technical Field

[0001] This application relates to the field of proppant technology, and in particular to a low-temperature self-polymerizing and curing sand-resistant proppant, its preparation method, and its application. Background Technology

[0002] In oil extraction, sand production from oil and water wells poses a significant hazard. If sand buries oil, gas, or water layers, it can lead to the shutdown of oil and gas wells, and the cessation of water injection, resulting in frequent downhole operations, equipment maintenance or replacement, and increased production costs. Excessive sand production can severely deplete the formation, easily creating cavities outside the reservoir casing, causing formation collapse, casing rupture and deformation, and even well abandonment. Therefore, implementing sand control measures for sand-producing wells is the primary measure to ensure normal oilfield production.

[0003] Chemical sand control involves cementing sand grains in loose sandstone reservoirs together, thereby stabilizing the formation structure and achieving a comprehensive solution. This method has advantages that other sand control measures cannot replace. The binders used in chemical sand control include phenolic resin, furan resin, polyurethane resin, and epoxy resin. Phenolic resin, furan resin, and polyurethane resin have high curing temperatures and very low curing strength at low temperatures, or even fail to cure. While epoxy resin can cure at low temperatures, it requires an organic solvent as a dispersion medium, and its curing strength in aqueous environments is low or almost non-curing. Plastic pre-coated sand control involves coating the surface of quartz sand with a special resin. After the solvent evaporates and the resin dries, it forms a pre-coated sand film, dispersed and individual grains. This process, as a relatively mature chemical sand control technology, has been widely used in oilfields both domestically and internationally. In particular, plastic pre-coated sand control is more effective in mid-to-late stage sand control wells with well temperatures above 50℃. However, its sand control effect is poor at well temperatures below 50℃. Existing technologies use plastic pre-coated sand at different temperature ranges, such as 45℃, 50℃, and 60℃. At 45℃, the plastic pre-coated sand exhibits severe adhesion, making construction inconvenient and requiring an external curing agent, which can lead to uneven solidification and affect the sand control effect. Furthermore, the plastic pre-coated sand at 50℃ and 60℃ requires 5-7 days to solidify under suitable temperature conditions, resulting in a long well dwell time.

[0004] Therefore, existing sand-control processes suffer from problems such as low consolidation strength, long consolidation time, or poor product performance under low-temperature curing conditions. Accordingly, there is an urgent need to provide a novel low-temperature self-polymerizing and curing sand-control proppant and its preparation method to improve these issues. Summary of the Invention

[0005] The main objective of this invention is to provide a low-temperature self-polymerizing and curing sand-resistant proppant, its preparation method, and its application, in order to solve the technical problems of low consolidation strength, long consolidation time, or poor product performance under low-temperature curing conditions in existing sand-resistant processes.

[0006] To achieve the above objectives, according to one aspect of the present invention, a low-temperature self-polymerizing and curing sand-resistant proppant is provided, wherein the weight parts of each component in the low-temperature self-polymerizing and curing sand-resistant proppant are: 100-150 parts of quartz sand, 7-9 parts of epoxy resin, 5-8 parts of diluent, 0.8-1.2 parts of curing agent, 0.5-0.7 parts of coupling agent, 1.7-1.9 parts of toughening agent, 0.8-1.2 parts of encapsulating agent, and 0.9-1.1 parts of nanoparticles; wherein the curing agent is a polyurethane material.

[0007] Furthermore, the diluent is an alcohol-based diluent, and the coupling agent is selected from one or more of KH-550 coupling agent, aminopropyltriethoxysilane, or methyltriethoxysiloxane.

[0008] Furthermore, the toughening agent is a diethylene glycol material, the coating agent is a resin material, and the nanoparticles are selected from one or more of barium titanate, lithium tantalate, barium strontium titanate, or lead zirconate titanate, with a particle size D50 of 20–50 nm.

[0009] Furthermore, the particle size D50 of the quartz sand is 0.2–1.2 mm, and the density is 1.4–1.6 g / cm³. 3 Its strength is 50-60 MPa.

[0010] Furthermore, the polyurethane material is selected from one or more of polyurea-type polyurethane, polyether-type polyurethane, or polycarbonate-type polyurethane; the alcohol diluent is selected from one or more of ethanol, isopropanol, or n-butanol; and the diethylene glycol material is selected from one or more of polyester polyol, dimethacrylate, or diallyl carbonate.

[0011] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a low-temperature self-polymerizing and curing sand-resistant proppant is provided. The method includes the following steps: Step S1, quartz sand is heated in a heating pot to obtain heated quartz sand, which is then divided into two groups by weight; Step S2, the first group of heated quartz sand, epoxy resin, and nanoparticles are mixed once in a tumbling pot, and then a coupling agent is added for a second mixing and a first cooling treatment to obtain an intermediate; Step S3, the intermediate, a coating agent, and a diluent are mixed three times in a tumbling pot to obtain proppant precursor A; Step S4, the second group of heated quartz sand, toughening agent, coating agent, and curing agent are mixed four times and cooled twice, and then a diluent is added for a fifth mixing treatment to obtain proppant precursor B; Step S5, proppant precursor A and proppant precursor B are mixed and ultrasonically treated to obtain a low-temperature self-polymerizing and curing sand-resistant proppant.

[0012] Further, in step S1, the heating temperature is 220-240℃ and the treatment time is 20-30 min; preferably, in step S2, the stirring speed for the first mixing is 800-1000 rpm, the stirring time is 1-1.5 h, and the cooling temperature is 150℃; preferably, step S2 includes: taking the first group of heated quartz sand, epoxy resin and nanoparticles and mixing them once in a tumbler, then adding the coupling agent in 5 portions, and performing a second mixing and a cooling treatment in sequence to obtain an intermediate.

[0013] Further, in step S3, the amount of coating agent and diluent added independently accounts for 50% of the total amount of coating agent and diluent, respectively; preferably, in step S4, the amount of coating agent and diluent added independently accounts for 50% of the total amount of coating agent and diluent, respectively; preferably, in step S3, the stirring time for the three mixing processes is 1 to 1.5 hours, and the stirring speed is 800 to 1000 rpm; preferably, in step S4, the temperature for the four mixing processes is 220 to 240°C, the stirring speed for the four and five mixing processes is 800 to 1000 rpm, and the processing time is 1 to 1.5 hours.

[0014] Further, in step S4, the temperature of the secondary cooling treatment is 150°C; preferably, in step S5, the weight ratio of proppant precursor A to proppant precursor B is 1:1, the frequency of ultrasonic treatment is 800-1000kHz, the treatment time is 15-20min, and the ultrasonic temperature is 20-25°C; preferably, in step S4, the diluent is added in three separate steps.

[0015] According to another aspect of the present invention, a low-temperature self-polymerizing and curing sand-resistant propping agent is provided for application in the fields of oil extraction, construction or chemical industry.

[0016] The low-temperature self-polymerizing and curing sand-resistant proppant of the present invention has the ability to solidify at low temperature (20-50℃), has high bonding strength, and is chemically stable. It has enhanced acid and alkali resistance, better compatibility with underlying fluids, and has broad prospects for industrial application. Attached Figure Description

[0017] 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. In the drawings:

[0018] Figure 1 A flowchart illustrating the preparation method of the low-temperature self-polymerizing and curing sand-resistant proppant in some embodiments of the present invention is shown; and

[0019] Figure 2 The experimental evaluation results of the effect of different curing times on the compressive strength and liquid phase permeability of the artificial rock core obtained by the proppant according to Example 1 of the present invention are shown. Detailed Implementation

[0020] 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.

[0021] As described in the background section of this invention, existing sand-control processes suffer from problems such as low consolidation strength, long consolidation time, or poor product performance under low-temperature curing conditions. Based on this, this invention provides a low-temperature self-polymerizing and curing sand-control proppant, wherein the weight percentages of each component are: 100-150 parts of quartz sand, 7-9 parts of epoxy resin, 5-8 parts of diluent, 0.8-1.2 parts of curing agent, 0.5-0.7 parts of coupling agent, 1.7-1.9 parts of toughening agent, 0.8-1.2 parts of encapsulating agent, and 0.9-1.1 parts of nanoparticles; wherein the curing agent is a polyurethane material.

[0022] Existing sand control materials typically involve coating sand with resinous additives to create a proppant. Traditional proppants exhibit a "single" curing characteristic, resulting in low curing strength and long curing times, thus affecting product performance and application range, especially at low temperatures where sand control effectiveness is significantly reduced. The low-temperature self-polymerizing and curing sand control proppant of this invention combines a bonding system and a curing system in its preparation process, resulting in a proppant product with high curing strength, simple curing, and the ability to cure at low temperatures. Specifically, the added curing agent is polyurethane. Polyurethane is a non-toxic curing agent with an amide-based active structure, exhibiting high reactivity and rapid curing in water, making it better suited to the working environment of downhole water. Furthermore, the low-temperature self-polymerizing and curing sand control proppant provided by this invention exhibits low-temperature (20–50°C) curing performance, high bonding strength, and chemical stability. Its enhanced acid and alkali resistance and superior compatibility with bottom fluids suggest broad prospects for industrial application.

[0023] To further improve the curing strength of the sand-control proppant, an alcohol-based diluent is preferred, and the coupling agent is selected from one or more of KH-550 coupling agent, aminopropyltriethoxysilane, or methyltriethoxysiloxane. Further preferred are diethylene glycol as the toughening agent, resin as the encapsulating agent, and nanoparticles selected from one or more of barium titanate, lithium tantalate, barium strontium titanate, or lead zirconate titanate, with a particle size D50 of 20–50 nm. The quartz sand has a particle size D50 of 0.2–1.2 mm and a density of 1.4–1.6 g / cm³. 3 Its strength is 50-60 MPa.

[0024] In a preferred embodiment, the polyurethane material is selected from one or more of polyurea-type polyurethane, polyether-type polyurethane, or polycarbonate-type polyurethane; the alcohol diluent is selected from one or more of ethanol, isopropanol, or n-butanol; and the diethylene glycol material is selected from one or more of polyester polyol, dimethacrylate, or diallyl carbonate. This allows for better utilization of the curing agent, fully leveraging the non-toxic, amide-active structure, and high reactivity of polyurethane, enabling rapid curing in water and better adapting it to the working environment of downhole water.

[0025] In another aspect, this invention provides a method for preparing a low-temperature self-polymerizing and curing sand-resistant proppant. The preparation method includes the following steps: Step S1, taking quartz sand and heating it in a heating pot to obtain heated quartz sand, and dividing it into two groups by weight; Step S2, taking the first group of heated quartz sand, epoxy resin, and nanoparticles and mixing them once in a tumbling pot, then adding a coupling agent and performing a second mixing and a cooling treatment to obtain an intermediate; Step S3, taking the intermediate, a coating agent, and a diluent and performing a third mixing treatment in a tumbling pot to obtain proppant precursor A; Step S4, taking the second group of heated quartz sand, toughening agent, coating agent, and curing agent and performing a fourth mixing and a second cooling treatment, then adding a diluent and performing a fifth mixing treatment to obtain proppant precursor B; Step S5, taking proppant precursor A and proppant precursor B and mixing them for ultrasonic treatment to obtain a low-temperature self-polymerizing and curing sand-resistant proppant.

[0026] The expert first heats the quartz sand in a heating pot to obtain heated quartz sand, which is then divided into two groups by weight. The first group of heated quartz sand, epoxy resin, and nanoparticles are mixed once in a tumbler, followed by the addition of a coupling agent and a second mixing and cooling process to obtain an intermediate. Next, the intermediate, a coating agent, and a diluent are mixed three times in the tumbler to obtain proppant precursor A. The second group of heated quartz sand, toughening agent, coating agent, and curing agent are mixed four times and cooled twice, followed by the addition of a diluent and a fifth mixing process to obtain proppant precursor B. Finally, proppant precursor A and proppant precursor B are mixed and ultrasonically treated to obtain a low-temperature self-polymerizing and curing sand-resistant proppant. The proppant prepared by the above method possesses both high curing strength and rapid low-temperature curing characteristics. Furthermore, the preparation method is mild, simple, and suitable for large-scale production, showing broad prospects for industrial application.

[0027] In a preferred embodiment, in step S1, the heating temperature is 220–240°C and the treatment time is 20–30 min, so that the quartz sand is heated evenly. More preferably, in step S2, the stirring speed for the first mixing is 800–1000 rpm, the stirring time is 1–1.5 h, and the cooling temperature is 150°C, so that the first group of heated quartz sand, epoxy resin, and nanoparticles are fully and evenly mixed in the tumbler. Step S2 includes: taking the first group of heated quartz sand, epoxy resin, and nanoparticles and mixing them once in the tumbler, then adding the coupling agent in 5 portions, and performing a second mixing and a cooling treatment in sequence to obtain an intermediate.

[0028] To ensure the diluent and coating agent function effectively in the preparation of the low-temperature self-polymerizing and curing sand-resistant support, in step S3, the amount of coating agent and diluent added is independently 50% of the total amount of coating agent and diluent, respectively. Then, in step S4, the amount of coating agent and diluent added is independently 50% of the total amount of coating agent and diluent, respectively. Furthermore, in step S3, the coating agent is added in four separate steps, with a 20-minute interval between each addition. To improve the uniformity of the raw material mixing, preferably, in step S3, the stirring time for the three mixing processes is 1–1.5 hours, and the stirring speed is 800–1000 rpm; in step S4, the temperature for the four mixing processes is 220–240°C, and the stirring speed for the four and five mixing processes is 800–1000 rpm, with a processing time of 1–1.5 hours.

[0029] In a preferred embodiment, in step S4, the temperature of the secondary cooling treatment is 150°C, and the treatment time is 1–1.5 h; in step S5, the weight ratio of proppant precursor A to proppant precursor B is 1:1, the ultrasonic treatment frequency is 800–1000 kHz, the treatment time is 15–20 min, and the ultrasonic temperature is 20–25°C, so that proppant precursor A and proppant precursor B are fully mixed, thereby further improving the curing strength of the proppant product. More preferably, in step S4, the diluent is added in three stages. The tumbler has the function of heat preservation for the material; the temperature difference between the material before and after the tumbler mixing treatment is 8–10°C.

[0030] In another aspect, the present invention provides a low-temperature self-curing sand-proofing proppant for use in the fields of oil extraction, construction, or chemical industry.

[0031] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0032] Example 1

[0033] The weight proportions of each component in the low-temperature self-polymerizing and curing sand-resistant proppant are as follows: 125 parts quartz sand, 8 parts epoxy resin, 7 parts diluent, 1 part curing agent, 0.6 parts coupling agent, 1.8 parts toughening agent, 1 part encapsulating agent, and 1 part nanoparticles. The curing agent is a polyurethane material, specifically a polyurea-type polyurethane; the alcohol diluent is ethanol; the toughening agent is epoxy resin; the coupling agent is KH-550 silane coupling agent; the nanoparticles are barium titanate with a particle size D50 of 30 nm; the encapsulating agent is KH-550 coupling agent; and the quartz sand has a particle size D50 of 0.2 mm and a density of 1.4 g / cm³. 3 Its maximum strength against breakage is 50 MPa.

[0034] The preparation steps are shown in the attached figure. The specific steps include: placing quartz sand in a heating pot and heating it to 220°C for 0.5 hours while stirring at 800 rpm for 1 hour. After heating, the quartz sand is kept in the heating pot for later use and divided into two groups by weight. Then, the first group of heated quartz sand is placed in a rolling pot. All the mass of epoxy resin and all the mass of nanoparticles are added to the pot and mixed with the quartz sand once while stirring at 800 rpm for 1 hour. Then, all the mass of coupling agent is taken out and added to the pot in five batches during the stirring process for a second mixing at 800 rpm for 1 hour. Finally, the mixture is cooled to 150°C to obtain an intermediate.

[0035] The above intermediate was added to a rolling pot, and half the mass of the coating agent and diluent were added to the rolling pot. The mixture was mixed three times at a stirring speed of 800 rpm for 1 hour. After the mixture was fully rolled, it was removed from the rolling pot and cooled to room temperature to prepare the proppant A. The coating agent was added to the pot in four batches, with an interval of 20 minutes between each addition of the outer coating agent.

[0036] After heating a second batch of quartz sand, it was added to a tumbler. Then, all the toughening agent, half the coating agent, and all the curing agent by weight were added, and the mixture was stirred four times at 800 rpm for 30 minutes at 240°C. Once the temperature dropped to 200°C, half the diluent by weight was added to the tumbler in three separate additions, and the mixture was stirred five times at 800 rpm for 1 hour. The mixture was then removed from the tumbler and cooled to room temperature to obtain proppant B. The tumbler served to maintain the material's temperature; the temperature difference between the material before and after the tumbler mixing process was 8°C.

[0037] Finally, the prepared proppant A and proppant B were mixed in a mass ratio of 1:1 and subjected to ultrasonic treatment to obtain a low-temperature self-polymerizing and curing sand-resistant proppant. The ultrasonic treatment time was 20 min, the frequency was 1000 kHz, and the temperature was 25 °C.

[0038] Example 2

[0039] The only difference from Example 1 is:

[0040] The weight proportions of each component in the low-temperature self-polymerizing and curing sand-resistant proppant are as follows: 125 parts quartz sand, 8 parts epoxy resin, 7 parts diluent, 1 part curing agent, 0.6 parts coupling agent, 1.8 parts toughening agent, 1 part encapsulating agent, and 1 part nanoparticles. Among them, the curing agent is a polyurethane material, specifically a polyether-type polyurethane; the alcohol diluent is isopropanol; the toughening agent is a polyester polyol; the coupling agent is aminopropyltriethoxysilane; and the nanoparticles are barium strontium titanate with a particle size D50 of 20 nm.

[0041] Example 3

[0042] The only difference from Example 1 is:

[0043] The weight proportions of each component in the low-temperature self-polymerizing and curing sand-resistant proppant are as follows: 150 parts quartz sand, 9 parts epoxy resin, 8 parts diluent, 1.2 parts curing agent, 0.7 parts coupling agent, 1.9 parts toughening agent, 1.2 parts encapsulating agent, and 1.1 parts nanoparticles. The curing agent is a polyurethane material, specifically polycarbonate-type polyurethane; the alcohol diluent is n-butanol; the toughening agent is dimethacrylate; the coupling agent is methyltriethoxysiloxane; the nanoparticles are lead zirconate titanate with a particle size D50 of 20 nm; and the encapsulating agent is a resin. The quartz sand has a particle size D50 of 1.2 mm and a density of 1.6 g / cm³. 3 Its maximum strength against breakage is 60 MPa.

[0044] Comparative Example 1

[0045] The only difference from Example 1 is that the curing agent used is a traditional curing agent, specifically an acrylate.

[0046] Comparative Example 2

[0047] The only difference from Example 1 is that the proppant product used is proppant precursor A.

[0048] Comparative Example 3

[0049] The only difference from Example 1 is that the proppant product used is proppant precursor B.

[0050] Performance testing

[0051] 1) Curing strength

[0052] The testing method is as follows:

[0053] ① Weigh 16.00g ± 0.50g of each of the sand-control proppant particles A and B in a 1:1 ratio according to the standard requirements, put them into a 100mL beaker and mix them evenly with a spatula. There are a total of 6 portions.

[0054] ② Use 22℃ clean water as the sand-carrying solution. Measure 30mL and pour it into a beaker. Stir well according to the standard requirements and pour out the sand-carrying solution. Use a spatula to put the sample into the core mold in 4 batches. Each time, it is necessary to compact and tamp it down. Make 6 cores in this way.

[0055] ③ Place the 6 core samples in a 30℃ constant temperature water bath for 48 hours.

[0056] ④ Remove the core sample and conduct a compressive strength test.

[0057] ⑤ Power on: Turn on the power and preheat for 30 minutes.

[0058] ⑥ Place the core on the lower pressure plate, press the "load zeroing" key to return the load to zero, and then press the "up" or "down" key to adjust the moving beam to the appropriate position.

[0059] ⑦ Press the "Test" button, then press the "Descend" button to start the test. After the sample is damaged, press the "Stop" button. The peak value recorded at this time is the maximum bearing capacity.

[0060] ⑧ Compressive strength is calculated using the formula: P = P1 / A × 100; where:

[0061] P – compressive strength, measured in megapascals (MPa);

[0062] P1—Peak pressure reading, in Newtons (N);

[0063] A – Core cross-sectional area, in square centimeters (cm²) 2 ).

[0064] The instruments used are:

[0065] ① Electronic balance: measuring range 0~200g, accuracy 0.1g.

[0066] ② Electric constant temperature drying oven: Temperature range: room temperature to 300℃.

[0067] ③ Hydraulic press: accuracy ±0.5%.

[0068] ④ Compression tester: accuracy is 1%.

[0069] ⑤ Measuring cylinders or beakers: 100mL, 500mL.

[0070] (2) Curing time

[0071] Curing time test method and equipment:

[0072] ①The core material for the low-temperature consolidation coating sand is quartz sand with a diameter of φ0.425~φ85mm.

[0073] ② The experimental materials consist of two types of coated particles, A and B, with a diameter of φ0.6-φ1.4mm, which are prepared by coating quartz sand. The two types of particles are mixed evenly and then the artificial sand core used in the experiment is prepared by a sand core device.

[0074] ③ Experimental instruments: constant temperature water bath, electronic tensile testing machine, high temperature and high pressure rock core flow tester.

[0075] The proppant products prepared in the above examples and comparative examples were subjected to the above performance tests, and the test results are shown in the table below.

[0076] Table 1 shows the curing strength test results of the proppant product prepared in Example 1 at different experimental temperatures;

[0077] Table 2 shows the experimental evaluation results of the effects of different curing times on the compressive strength and liquid phase permeability of the artificial rock core obtained by the proppant in Example 1; and

[0078] Table 3 shows the consolidation strength of the proppant products prepared in the examples and comparative examples at a constant temperature of 20°C and a curing time (consolidation time) of 48 h.

[0079] Table 1

[0080]

[0081] Table 2

[0082] Time / h Consolidation strength / MPa <![CDATA[Permeability / μm 2 > 0 2.6 4.6 2 4.5 4.53 4 5.9 4.52 6 7.6 4.49 8 9.4 4.44 10 10 4.44 12 10.3 4.42 14 10.9 4.42

[0083] Table 3

[0084] Consolidation strength (MPa) Consolidation time (h) Example 1 13.14 48 Example 2 13.00 48 Example 3 12.85 48 Comparative Example 1 9.45 48 Comparative Example 2 8.21 48 Comparative Example 3 8.16 48

[0085] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0086] The test results in Tables 1, 2, and 3 above show that the compressive strength of the proppant prepared by this invention remains stable under different experimental temperatures and consolidation times. Compared with proppants prepared by traditional methods, the proppant provided by this invention exhibits superior compressive strength and stability under the same consolidation temperature and time. Figure 2 The test results show that the consolidation strength of the artificial rock core gradually increases with the extension of the curing time. It has a consolidation strength of more than 6 MPa after 6 hours and a strength of more than 10 MPa after 10 hours.

[0087] In summary, the low-temperature self-polymerizing and curing sand-resistant proppant of the present invention has the ability to solidify at low temperatures (20-50°C), has high bonding strength, and is chemically stable. It also has enhanced acid and alkali resistance, better compatibility with underlying fluids, and has broad prospects for industrial application.

[0088] While this specification contains numerous specific implementation details, these should not be construed as limiting the scope of any invention or the scope of the claims, but rather are primarily intended to describe features of specific embodiments of a particular invention. Certain features described in the various embodiments herein may also be implemented in combination in a single embodiment. Conversely, various features described in a single embodiment may also be implemented separately in various embodiments or in any suitable sub-combination. Furthermore, while features may function in certain combinations as described above and even initially claimed in this way, one or more features from a claimed combination may be removed from that combination in some cases, and a claimed combination may refer to a sub-combination or a variation thereof.

[0089] Similarly, although the operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring these operations to be performed in the specific order shown or sequentially, or requiring all illustrated operations to be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system modules and components in the above embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0090] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings are not necessarily shown in a specific order or sequence to achieve the desired result. In some implementations, multitasking and parallel processing may be advantageous.

[0091] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0092] 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 low-temperature self-polymerizing and curing sand-resistant proppant, characterized in that, The low-temperature self-polymerizing and curing sand-resistant proppant comprises the following components by weight: 100-150 parts of quartz sand, 7-9 parts of epoxy resin, 5-8 parts of diluent, 0.8-1.2 parts of curing agent, 0.5-0.7 parts of coupling agent, 1.7-1.9 parts of toughening agent, 0.8-1.2 parts of encapsulating agent, and 0.9-1.1 parts of nanoparticles; wherein the curing agent is a polyurethane material.

2. The low-temperature self-polymerizing and curing sand-resistant proppant according to claim 1, characterized in that, The diluent is an alcohol-based diluent, and the coupling agent is selected from one or more of KH-550 coupling agent, aminopropyltriethoxysilane, or methyltriethoxysiloxane.

3. The low-temperature self-polymerizing and curing sand-resistant proppant according to claim 1 or 2, characterized in that, The toughening agent is a diethylene glycol material, the coating agent is a resin material, and the nanoparticles are selected from one or more of barium titanate, lithium tantalate, barium strontium titanate, or lead zirconate titanate, with a particle size D50 of 20-50 nm.

4. The low-temperature self-polymerizing and curing sand-resistant proppant according to any one of claims 1 to 3, characterized in that, The quartz sand has a particle size D50 of 0.2–1.2 mm and a density of 1.4–1.6 g / cm³. 3 Its maximum strength against breakage is 50-60 MPa.

5. The low-temperature self-polymerizing and curing sand-resistant proppant according to any one of claims 1 to 4, characterized in that, The polyurethane material is selected from one or more of polyurea polyurethane, polyether polyurethane, or polycarbonate polyurethane; the alcohol diluent is selected from one or more of ethanol, isopropanol, or n-butanol; and the diethylene glycol material is selected from one or more of polyester polyol, dimethacrylate, or diallyl carbonate.

6. A method for preparing a low-temperature self-polymerizing and curing sand-resistant proppant according to any one of claims 1 to 5, characterized in that, The preparation method includes the following steps: Step S1: Take quartz sand and heat it in a heating pot to obtain heated quartz sand, and divide it into two groups by weight. Step S2: Take the heated quartz sand, epoxy resin and nanoparticles from the first group and mix them once in a tumbler. Then add a coupling agent and mix them a second time and cool them down once to obtain an intermediate. Step S3: Take the intermediate, coating agent and diluent and mix them three times in a tumbling pot to obtain proppant precursor A; Step S4: Take the heated quartz sand, toughening agent, coating agent and curing agent from the second group and mix them four times and cool them down twice in sequence. Then add the diluent and mix them five times to obtain the proppant precursor B. Step S5: Mix the proppant precursor A and the proppant precursor B and perform ultrasonic treatment to obtain the low-temperature self-polymerizing and curing sand-resistant proppant.

7. The preparation method according to claim 6, characterized in that, In step S1, the temperature of the heating treatment is 220-240°C, and the treatment time is 20-30 minutes. Preferably, in step S2, the stirring speed for the first mixing is 800-1000 rpm, the stirring time is 1-1.5 h, and the temperature for the cooling treatment is 150°C. Preferably, step S2 includes: taking the first group of heated quartz sand, epoxy resin and nanoparticles and mixing them once in a rolling pot, then adding the coupling agent in 5 batches, and performing a second mixing and a cooling treatment to obtain an intermediate.

8. The preparation method according to claim 6, characterized in that, In step S3, the amount of the coating agent and the diluent added each accounts for 50% of the total amount of the coating agent and the total amount of the diluent, respectively. Preferably, in step S4, the amount of the coating agent and the diluent added each accounts for 50% of the total amount of the coating agent and the total amount of the diluent, respectively. Preferably, in step S3, the stirring time for the three mixing processes is 1 to 1.5 hours, and the stirring speed is 800 to 1000 rpm. Preferably, in step S4, the temperature of the four mixing processes is 220-240°C, the stirring speed of the four mixing processes and the fifth mixing process is 800-1000 rpm, and the processing time is 1-1.5 h.

9. The preparation method according to claim 6, characterized in that, In step S4, the temperature of the secondary cooling process is 150°C; Preferably, in step S5, the weight ratio of the proppant precursor A to the proppant precursor B is 1:1, the frequency of the ultrasonic treatment is 800-1000 kHz, the treatment time is 15-20 min, and the ultrasonic temperature is 20-25 °C. Preferably, in step S4, the diluent is added in three separate steps.

10. The application of a low-temperature self-polymerizing and curing sand-control proppant obtained by the preparation method of any one of claims 6 to 9 in the fields of oil extraction, construction or chemical industry.

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