Temperature-controlled self-polymerizing sand consolidation proppant and method of making same
By modifying the proppant and grafting it with a temperature-sensitive material, a temperature-controlled self-polymerizing sand-fixing proppant is formed, which solves the problem of poor flowability in the existing technology, achieves efficient proppant sand fixation and flowability, reduces proppant reflux rate, and extends equipment life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA NAT PETROLEUM CORP
- Filing Date
- 2024-11-28
- Publication Date
- 2026-05-29
AI Technical Summary
Existing sand-fixing proppants have poor conductivity during fracturing, resulting in a high proppant backflow rate, which affects fracture conductivity and oil and gas recovery rate.
By modifying the proppant and grafting it with a temperature-sensitive material, the proppant undergoes a change in molecular conformation at reservoir temperature. The materials are then bonded together through chemical bonds and physical entanglement to form a temperature-controlled self-polymerizing sand-fixing proppant that maintains high conductivity.
It effectively improves the proppant's resistance to backflow and its flow-guiding ability, reduces construction procedures and costs, avoids proppant clogging of oil and gas channels, and extends equipment life.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of fracturing additives, specifically a temperature-controlled self-polymerizing sand-fixing proppant and its preparation method. Background Technology
[0002] In the extraction of fluid minerals such as oil and natural gas, fracturing technology is often required. This involves using a surface high-pressure pump unit to inject fracturing fluid into the formation to open fractures. To prevent the underground fractures from closing and to maintain oil and gas channels and conductivity, proppant must be used to fill the fractures. Props are made of hard, pressure-resistant solid particles, such as quartz sand or ceramic particles, used to support the fractures and form flow channels, allowing oil and gas to flow into the wellbore. Therefore, the quality of the proppant and its placement method directly determine the production enhancement effect after fracturing.
[0003] Proppant desandering is one of the most common problems after fracturing, sometimes with a backflow rate as high as 20%. The main reasons include: high drag force generated during fracturing fluid flowback, low closure stress, and unsuitable proppant size or density. Desandering causes many negative consequences, such as: reducing fracture width and decreasing fracturing volume; blocking seepage channels and reducing oil and gas recovery; and the discharged proppant corroding downhole equipment and surface pipelines, shortening their service life.
[0004] Currently, there are two common treatment methods. The first is to coat the surface of the proppant with resin and add a curing agent to solidify the proppant downhole. However, because the curing agent has good fluidity, it easily enters the pores of the proppant and solidifies, blocking the flow channels. The second method is to add fiber for sand fixation, but fiber degradation can lead to structural collapse, proppant migration, or small degraded particles that block the channels, reducing permeability. Although existing technologies can control the backflow capacity of the proppant, they all reduce the conductivity of the fracture to some extent, thus reducing the production per well. Summary of the Invention
[0005] This invention provides a temperature-controlled self-polymerizing sand-fixing proppant and its preparation method, which overcomes the shortcomings of the prior art and can effectively solve the problem of poor flowability of existing sand-fixing proppants.
[0006] One of the technical solutions of the present invention is achieved through the following measures: a temperature-controlled self-polymerizing sand-fixing proppant, comprising, by weight, 100 to 150 parts proppant, 12 to 25 parts surface modifier, 30 to 75 parts temperature-sensitive material, 1.2 to 2.0 parts initiator, and 300 to 400 parts organic solvent. The surface modifier is composed of a silane coupling agent and an accelerator in a mass ratio of 1:0.1 to 0.7. The temperature-sensitive material is composed of temperature-sensitive material A and temperature-sensitive material B in a mass ratio of 1:0.1 to 0.9.
[0007] The following are further optimizations and / or improvements to one of the above-mentioned inventive technical solutions: The aforementioned temperature-sensitive material A is a hydrophilic polymer, which is one or more of the following: polyoxyethylene, polyvinyl alcohol, gelatin, hyaluronic acid, and alginate.
[0008] The aforementioned thermosensitive material B is a thermosensitive hydrophobic polymer, which is one or more of poly(n-isopropylacrylamide), polypropylene oxide, polyimide, polybenzimidazole, polyvinylidene fluoride, and polyethersulfone.
[0009] The aforementioned silane coupling agent is one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, 3-(2-aminoethyl)-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)-aminopropylmethyldimethoxysilane.
[0010] The aforementioned accelerator is ferrocene.
[0011] The aforementioned proppant is one or more of the following: natural quartz sand, ceramsite, artificial glass spheres, rubber granules, and aluminum spheres.
[0012] The mesh size of the aforementioned proppant is one of 20 to 40 mesh, 40 to 70 mesh, and 70 to 140 mesh.
[0013] The aforementioned initiator is composed of azobisisobutyronitrile and cuprous bromide in a mass ratio of 1:0.5 to 0.7.
[0014] The organic solvent mentioned above is dimethyl sulfoxide.
[0015] The above-mentioned temperature-controlled self-polymerizing sand-fixing proppant is obtained by the following method: S1, add the required amount of surfactant to the ethanol aqueous solution, then add the required amount of proppant and stir to obtain a mixture; S2, after heating the mixture, the pH value of the mixture is adjusted, the mixture is stirred and allowed to stand to react, and the reaction product is obtained. After filtering and drying the reaction product, the modified proppant is obtained. S3, under a nitrogen atmosphere, the required amount of modified proppant, temperature-sensitive material and initiator are added to an organic solvent and stirred to carry out a polymerization reaction. After the reaction is completed, the temperature is maintained, and after filtration and drying, a temperature-controlled self-polymerizing sand-fixing proppant is obtained.
[0016] In step S1 above, the amount of ethanol aqueous solution added is 5 to 8 times the mass of the silane coupling agent, and the mass concentration of the ethanol aqueous solution is 8% to 12%.
[0017] In step S1 above, the stirring time is 30 min to 60 min.
[0018] In step S2 above, the heating temperature is 80°C to 90°C, and the pH of the mixture is adjusted to 4.0 to 4.5 using acetic acid.
[0019] In step S2 above, the stirring speed is 500 r / min to 600 r / min, the stirring time is 2 h to 4 h, and the settling time is 7 h to 9 h.
[0020] In step S3 above, the stirring speed is 300 r / min to 350 r / min, the pH value during the reaction is 6 to 7, the reaction temperature is 60℃ to 80℃, the reaction time is 4h to 6h, and the heat preservation time is 1h to 3h.
[0021] The second technical solution of the present invention is achieved through the following measures: a method for preparing a temperature-controlled self-polymerizing sand-fixing proppant, which is carried out according to the following method: S1, add the required amount of surfactant to the ethanol aqueous solution, then add the required amount of proppant and stir to obtain a mixture; S2, after heating the mixture, the pH value of the mixture is adjusted, the mixture is stirred and allowed to stand to react, and the reaction product is obtained. After filtering and drying the reaction product, the modified proppant is obtained. S3, under a nitrogen atmosphere, the required amount of modified proppant, temperature-sensitive material and initiator are added to an organic solvent and stirred to carry out a polymerization reaction. After the reaction is completed, the temperature is maintained, and after filtration and drying, a temperature-controlled self-polymerizing sand-fixing proppant is obtained.
[0022] The temperature-controlled self-polymerizing sand-fixing proppant of this invention has excellent compressive strength, conductivity, and anti-backflow ability. By modifying the proppant and then grafting a temperature-sensitive material onto the surface of the modified proppant, the temperature-controlled self-polymerizing sand-fixing proppant undergoes a molecular conformation change at the reservoir temperature after entering the fracture. The surfaces of the temperature-controlled self-polymerizing sand-fixing proppant are bonded together through both chemical bonding and physical entanglement, maintaining high conductivity while fixing sand, effectively solving the problem of poor conductivity in existing sand-fixing proppants. Attached Figure Description
[0023] Figure 1 The diagram shows the flow conductivity test results of the temperature-controlled self-polymerizing sand proppant prepared in Examples 17 and 18 of this invention.
[0024] Figure 2 The diagram shows the flow conductivity test of the temperature-controlled self-polymerizing sand proppant prepared in Example 18 of this invention. Detailed Implementation
[0025] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemicals mentioned in this invention are well-known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.
[0026] The present invention will be further described below with reference to embodiments: Example 1: The temperature-controlled self-polymerizing sand-fixing proppant comprises, by weight, 100 to 150 parts proppant, 12 to 25 parts surface modifier, 30 to 75 parts temperature-sensitive material, 1.2 to 2.0 parts initiator, and 300 to 400 parts organic solvent. The surface modifier is composed of a silane coupling agent and an accelerator in a mass ratio of 1:0.1 to 0.7. The temperature-sensitive material is composed of temperature-sensitive material A and temperature-sensitive material B in a mass ratio of 1:0.1 to 0.9.
[0027] Example 2: As an optimization of the above example, the temperature-sensitive material A is a hydrophilic polymer, which is one or more of polyoxyethylene, polyvinyl alcohol, gelatin, hyaluronic acid and alginate.
[0028] Example 3: As an optimization of the above example, the thermosensitive material B is a thermosensitive hydrophobic polymer, which is one or more of poly(n-isopropylacrylamide), polypropylene oxide, polyimide, polybenzimidazole, polyvinylidene fluoride and polyethersulfone.
[0029] Example 4: As an optimization of the above examples, the silane coupling agent is one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, 3-(2-aminoethyl)-aminopropyltrimethoxysilane and 3-(2-aminoethyl)-aminopropylmethyldimethoxysilane.
[0030] Example 5: As an optimization of the above examples, the accelerator is ferrocene.
[0031] In this invention, the raw material ferrocene can increase its solubility through coordination, thereby improving the modification effect. Furthermore, the rigid groups in the raw material ferrocene can enhance the compressive strength of the temperature-controlled self-polymerizing sand proppant.
[0032] Example 6: As an optimization of the above examples, the proppant is one or more of natural quartz sand, ceramsite, artificial glass spheres, rubber granules and aluminum spheres.
[0033] Example 7: As an optimization of the above examples, the mesh size of the proppant is one of 20 to 40 mesh, 40 to 70 mesh, and 70 to 140 mesh.
[0034] Example 8: As an optimization of the above examples, the initiator is composed of azobisisobutyronitrile and cuprous bromide in a mass ratio of 1:0.5 to 0.7.
[0035] Example 9: As an optimization of the above examples, the organic solvent is dimethyl sulfoxide.
[0036] Example 10: As an optimization of the above examples, a temperature-controlled self-polymerizing sand-fixing proppant was obtained by the following method: S1, add the required amount of surfactant to the ethanol aqueous solution, then add the required amount of proppant and stir to obtain a mixture; S2, after heating the mixture, the pH value of the mixture is adjusted, the mixture is stirred and allowed to stand to react, and the reaction product is obtained. After filtering and drying the reaction product, the modified proppant is obtained. S3, under a nitrogen atmosphere, the required amount of modified proppant, temperature-sensitive material and initiator are added to an organic solvent and stirred to carry out a polymerization reaction. After the reaction is completed, the temperature is maintained, and after filtration and drying, a temperature-controlled self-polymerizing sand-fixing proppant is obtained.
[0037] Example 11: As an optimization of the above example, in step S1, the amount of ethanol aqueous solution added is 5 to 8 times the mass of the silane coupling agent, and the mass concentration of the ethanol aqueous solution is 8% to 12%.
[0038] Example 12: As an optimization of the above example, in step S1, the stirring time is 30 min to 60 min.
[0039] Example 13: As an optimization of the above example, in step S2, the heating temperature is 80°C to 90°C, and the pH of the mixture is adjusted to 4.0 to 4.5 with acetic acid.
[0040] Example 14: As an optimization of the above example, in step S2, the stirring speed is 500 r / min to 600 r / min, the stirring time is 2 h to 4 h, and the settling time is 7 h to 9 h.
[0041] Example 15: As an optimization of the above example, in step S3, the stirring speed is 300 r / min to 350 r / min, the pH value is 6 to 7, the reaction temperature is 60°C to 80°C, the reaction time is 4 h to 6 h, and the heat preservation time is 1 h to 3 h.
[0042] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention relates to a temperature-controlled self-polymerizing sand-fixing proppant, the sand-fixing principle of which is mainly achieved by modifying the proppant and then grafting a temperature-sensitive material onto the surface of the modified proppant.
[0043] Specifically, firstly, to ensure a firm bond between the temperature-sensitive material and the support surface, the support needs to be modified using surface modifiers (silane coupling agents and accelerators). Specifically, the silane coupling agent undergoes hydrolysis under acidic conditions to form a siloxane compound containing silanol bonds (-Si-OH). These silanol bonds interact with the hydroxyl groups on the support surface to form hydrogen bonds. During the heating and curing process, a dehydration reaction occurs, and covalent bonds are formed with the functional groups. Then, a grafting reaction of temperature-sensitive materials was carried out on the surface of the modified proppant. The temperature-sensitive material is a block compound composed of hydrophilic segments (temperature-sensitive material A) and hydrophobic segments (temperature-sensitive material B). In response to formation temperature, it undergoes a conformational transformation, with the hydrophobic segments contracting and the hydrophilic segments expanding outward, entangled with the hydrophilic segments of adjacent proppants. Simultaneously, because the hydrophilic segments (temperature-sensitive material A) mostly contain ether bonds, multiple hydrogen bonds easily form between the molecular chains, enhancing the sand-fixing ability. Furthermore, the temperature-controlled self-polymerizing sand-fixing proppant maintains a large number of voids, allowing the fractures to retain high conductivity. Finally, in this invention, the conformational transition temperature of the temperature-controlled self-polymerizing sand-fixing proppant is controlled by using preferred temperature-sensitive materials A and B, so that its activation temperature is between 50°C and 90°C. The introduction of these temperature-sensitive materials prevents the proppant from prematurely agglomerating and clumping during transportation, storage, and construction, which could affect proppant performance and construction efficiency, and even cause sand blockage risks. In summary, this invention utilizes a temperature-controlled self-polymerizing proppant, obtained by coating conventional proppant with a temperature-sensitive material composed of hydrophilic segments (temperature-sensitive material A) and hydrophobic segments (temperature-sensitive material B). This proppant activates its sand-fixing effect based on the underlying temperature, preventing premature agglomeration during transportation, storage, and construction, which could negatively impact proppant performance, construction efficiency, or even cause sand blockage. This temperature-controlled self-polymerizing proppant maintains high conductivity while fixing sand, preventing blockage of oil and gas channels. Furthermore, this invention eliminates the need for curing agents or fibers; the proppant itself polymerizes and bonds, reducing material usage, construction steps, and costs. It also reduces proppant runoff, contributing to formation fracture stability, minimizing damage to conductivity, and extending equipment lifespan.
[0044] Example 16: This temperature-controlled self-polymerizing sand-fixing proppant comprises, by weight, 100g proppant (20-40 mesh ceramsite, Henan Zhengnai New Materials Co., Ltd.), 10g silane coupling agent (γ-aminopropyltriethoxysilane), 2g accelerator (ferrocene), 30g temperature-sensitive material A (polyoxyethylene), 5g temperature-sensitive material B (poly(n-isopropylacrylamide), 1.2g initiator (0.8g azobisisobutyronitrile and 0.4g cuprous bromide), and 300mL organic solvent (dimethyl sulfoxide), obtained by the following method: S1. Add the required amount of silane coupling agent and accelerator to 50 mL of 10% ethanol aqueous solution, then add the required amount of support agent and stir. Stir magnetically for 30 min to disperse the mixture evenly. S2, after heating the mixture to 85℃, the pH of the mixture was adjusted to 4.5 with acetic acid. The mixture was stirred at 500r / min for 3h and then allowed to stand for 8h to obtain the reaction product. After filtering and drying the reaction product, the modified proppant was obtained. S3. Under a nitrogen atmosphere, the required amount of modified proppant, temperature-sensitive material and initiator are added to an organic solvent. The mixture is stirred and polymerization begins for 4 hours at a temperature of 60℃, a rotation speed of 300 r / min and a pH of 6. After the reaction is completed, the mixture is kept at the same temperature for another 2 hours. After filtration and drying, the temperature-controlled self-polymerizing sand proppant is obtained.
[0045] Example 17: This temperature-controlled self-polymerizing sand-fixing proppant comprises, by weight, 120g proppant (40-70 mesh ceramsite, Henan Zhengnaixin New Materials Co., Ltd.), 12g silane coupling agent (γ-aminopropyltriethoxysilane), 7g accelerator (ferrocene), 30g temperature-sensitive material A (20g polyvinyl alcohol, 10g hyaluronic acid), 10g temperature-sensitive material B (poly(n-isopropylacrylamide)), 1.6g initiator (1.0g azobisisobutyronitrile and 0.6g cuprous bromide), and 300mL organic solvent (dimethyl sulfoxide), obtained by the following method: S1. Add the required amount of silane coupling agent and accelerator to 50 mL of 10% ethanol aqueous solution, then add the required amount of support agent and stir. Stir magnetically for 60 min to disperse the mixture evenly. S2, after heating the mixture to 85℃, the pH of the mixture was adjusted to 4.5 with acetic acid. The mixture was stirred at 500r / min for 3h and then allowed to stand for 8h to obtain the reaction product. After filtering and drying the reaction product, the modified proppant was obtained. S3, under a nitrogen atmosphere, the required amount of modified proppant, temperature-sensitive material and initiator are added to an organic solvent. The mixture is stirred at 70℃, 350 r / min and pH 6 and polymerization begins for 4 hours. After the reaction is completed, the mixture is kept at the temperature for another 2 hours. After filtration and drying, a temperature-controlled self-polymerizing sand-fixing proppant is obtained.
[0046] Example 18: This temperature-controlled self-polymerizing sand-fixing proppant comprises, by weight, 150g proppant (ceramsite with a mesh size of 70 to 140 mesh, from Henan Zhengnai New Materials Co., Ltd.), 15g silane coupling agent (γ-aminopropyltriethoxysilane), 10g accelerator (ferrocene), 60g temperature-sensitive material A (polyoxyethylene), 15g temperature-sensitive material B (polypropylene oxide), 2.0g initiator (1.2g azobisisobutyronitrile and 0.8g cuprous bromide), and 300mL organic solvent (dimethyl sulfoxide), obtained by the following method: S1. Add the required amount of silane coupling agent and accelerator to 80 mL of 10% ethanol aqueous solution, then add the required amount of support agent and stir. Stir magnetically for 60 min to disperse the mixture evenly. S2, after heating the mixture to 85℃, the pH of the mixture was adjusted to 4.5 with acetic acid. The mixture was stirred at 500r / min for 3h and then allowed to stand for 8h to obtain the reaction product. After filtering and drying the reaction product, the modified proppant was obtained. S3, under a nitrogen atmosphere, the required amount of modified proppant, temperature-sensitive material and initiator are added to an organic solvent. The mixture is stirred and polymerized for 4 hours at a temperature of 70℃, a rotation speed of 350 r / min and a pH of 6. After the reaction is completed, the mixture is kept at the temperature for another 2 hours. After filtration and drying, a temperature-controlled self-polymerizing sand-fixing proppant is obtained.
[0047] Comparative Example 1: This sand-fixing proppant comprises, by weight, 100g proppant (20-40 mesh ceramsite, Henan Zhengnaixin New Materials Co., Ltd.), 30g thermosensitive material A (polyoxyethylene), 5g thermosensitive material B (poly(n-isopropylacrylamide), 1.2g initiator (0.8g azobisisobutyronitrile and 0.4g cuprous bromide), and 300mL organic solvent (dimethyl sulfoxide), obtained by the following method: The first step involves adding the required amount of proppant, thermosensitive material, and initiator to an organic solvent under a nitrogen atmosphere. The mixture is stirred and polymerization begins at 60°C, 300 r / min, and pH 6 for 4 hours. After the reaction is complete, the mixture is kept at the same temperature for another 2 hours. After filtration and drying, the solidified proppant is obtained.
[0048] Comparative Example 2: The difference from Embodiment 18 of the present invention is that the raw materials “60g of temperature-sensitive material A (polyoxyethylene) and 15g of temperature-sensitive material B (polypropylene oxide)” are changed to “75g of phenolic resin”, and the rest of the steps are the same.
[0049] Experimental Example 1: Investigating the basic properties of the temperature-controlled self-polymerizing sand proppant of the present invention.
[0050] Experimental Methods: Following the methods specified in SY / T 5108-2014 "Performance of Proppants for Hydraulic Fracturing and Gravel Packing Operations," the basic properties of the temperature-controlled self-polymerizing sand-fixing proppants prepared in Examples 16 to 18 of this invention were investigated. Simultaneously, the sand-fixing proppants prepared in Comparative Examples 1 to 2 of this invention and the original ceramsite were used as controls. The basic properties investigated included size (mesh), roundness, sphericity, and bulk density (g / cm³). 3 ) and the breakage rate at 69MPa.
[0051] Experimental results: The basic properties of the temperature-controlled self-polymerizing sand-fixing proppant of the present invention are shown in Table 1. As can be seen from Table 1, the temperature-controlled self-polymerizing sand-fixing proppant prepared in Examples 16 to 18 of the present invention has less impact on roundness, sphericity and bulk density compared with the original ceramsite, and the breakage rate is significantly reduced. As can be seen from the data of Comparative Examples 1 and 2 and Example 18, the breakage rate of the temperature-controlled self-polymerizing sand-fixing proppant prepared in Examples 16 to 18 of the present invention is significantly reduced. This indicates that in the preparation of the temperature-controlled self-polymerizing sand-fixing proppant of the present invention, after modifying the proppant (original ceramsite) or introducing a temperature-sensitive material composed of temperature-sensitive material A and temperature-sensitive material B, the temperature-controlled self-polymerizing sand-fixing proppant of the present invention greatly reduces the breakage rate and improves the compressive strength.
[0052] Experimental Example 2: To investigate the flow-conducting ability of the temperature-controlled self-polymerizing sand proppant of the present invention.
[0053] Experimental Methods: The temperature-controlled self-polymerizing proppants prepared in Examples 17 and 18 of this invention were tested according to the methods specified in industry standard SY / T 6302-2019 "Test Method for Conductivity of Fracturing Proppants". Meanwhile, the modified proppants prepared in step S2 of Examples 17 and 18 of this invention were used as controls.
[0054] Experimental results: The conductivity test diagram of the temperature-controlled self-polymerizing sand-fixing proppant of this invention is shown below. Figure 1 As shown, 1 is the modified proppant prepared in Example 17 of the present invention, 2 is the temperature-controlled self-polymerizing sand-fixing proppant prepared in Example 17 of the present invention, 3 is the modified proppant prepared in Example 18 of the present invention, and 4 is the temperature-controlled self-polymerizing sand-fixing proppant prepared in Example 18 of the present invention. Figure 1It can be seen that regardless of whether the original ceramsite has a mesh size of 40 to 70 mesh or 70 to 140 mesh, the modified proppant before and after coating with the temperature-sensitive material does not affect its conductivity and maintains good conductivity.
[0055] Experimental Example 3: To investigate the anti-backflow ability of the temperature-controlled self-polymerizing sand proppant of the present invention.
[0056] Experimental Methods: The backflow resistance of the temperature-controlled self-polymerizing sand proppant prepared in Example 18 of this invention was tested using an API standard flow meter. The liquid flow rate corresponding to the sand exiting the guide chamber is called the critical velocity. That is, the higher the critical velocity, the stronger the backflow resistance. Meanwhile, the original ceramsite was used as a control.
[0057] Experimental Results: The backflow resistance of the temperature-controlled self-polymerizing sand-fixing proppant prepared in Example 18 of this invention was tested by... Figure 2 As shown, by Figure 2 It can be seen that, under different closure stresses, the critical flow rate of the temperature-controlled self-polymerizing sand-fixing proppant prepared in Example 18 of this invention is higher than that of the original ceramsite, indicating that the temperature-controlled self-polymerizing sand-fixing proppant of this invention has a higher resistance to backflow. Furthermore, at a design temperature of approximately 75°C, the temperature-controlled self-polymerizing sand-fixing proppant of this invention undergoes a conformational change, enhancing the sand-fixing effect and significantly increasing the critical flow rate.
[0058] In summary, the temperature-controlled self-polymerizing sand-fixing proppant of this invention has excellent compressive strength, conductivity, and anti-backflow capability. By modifying the proppant and then grafting a temperature-sensitive material onto the surface of the modified proppant, the temperature-controlled self-polymerizing sand-fixing proppant undergoes a molecular conformation change at the reservoir temperature after entering the fracture. The surfaces of the temperature-controlled self-polymerizing sand-fixing proppant are bonded together through both chemical bonding and physical entanglement, maintaining high conductivity while fixing sand, effectively solving the problem of poor conductivity in existing sand-fixing proppants.
[0059] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.
Claims
1. A temperature-controlled self-polymerizing sand-fixing proppant, characterized in that... The raw materials, by weight, include 100 to 150 parts of proppant, 12 to 25 parts of surface modifier, 30 to 75 parts of thermosensitive material, 1.2 to 2.0 parts of initiator, and 300 to 400 parts of organic solvent. The surface modifier is composed of a silane coupling agent and an accelerator in a mass ratio of 1:0.1 to 0.
7. The thermosensitive material is composed of thermosensitive material A and thermosensitive material B in a mass ratio of 1:0.1 to 0.
9.
2. The temperature-controlled self-polymerizing sand-fixing proppant according to claim 1, characterized in that... Thermosensitive material A is a hydrophilic polymer, which is one or more of polyoxyethylene, polyvinyl alcohol, gelatin, hyaluronic acid and alginate; and / or thermosensitive material B is a thermosensitive hydrophobic polymer, which is one or more of poly(n-isopropylacrylamide), polypropylene oxide, polyimide, polybenzimidazole, polyvinylidene fluoride and polyethersulfone.
3. The temperature-controlled self-polymerizing sand-fixing proppant according to claim 1 or 2, characterized in that... The silane coupling agent is one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, 3-(2-aminoethyl)-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)-aminopropylmethyldimethoxysilane; or / and the accelerator is ferrocene.
4. The temperature-controlled self-polymerizing sand-fixing proppant according to claim 1, 2, or 3, characterized in that... The proppant is one or more of natural quartz sand, ceramsite, artificial glass spheres, rubber granules and aluminum spheres; or / and the mesh size of the proppant is one of 20 to 40 mesh, 40 to 70 mesh and 70 to 140 mesh.
5. The temperature-controlled self-polymerizing sand-fixing proppant according to any one of claims 1 to 4, characterized in that... The initiator is composed of azobisisobutyronitrile and cuprous bromide in a mass ratio of 1:0.5 to 0.7; and / or the organic solvent is dimethyl sulfoxide.
6. The temperature-controlled self-polymerizing sand-fixing proppant according to any one of claims 1 to 5, characterized in that... Obtained using the following method: S1, add the required amount of surfactant to the ethanol aqueous solution, then add the required amount of proppant and stir to obtain a mixture; S2, after heating the mixture, the pH value of the mixture is adjusted, the mixture is stirred and allowed to stand to react, and the reaction product is obtained. After filtering and drying the reaction product, the modified proppant is obtained. S3, under a nitrogen atmosphere, the required amount of modified proppant, temperature-sensitive material and initiator are added to an organic solvent and stirred to carry out a polymerization reaction. After the reaction is completed, the temperature is maintained, and after filtration and drying, a temperature-controlled self-polymerizing sand-fixing proppant is obtained.
7. The temperature-controlled self-polymerizing sand-fixing proppant according to claim 6, characterized in that... In step S1, the amount of ethanol aqueous solution added is 5 to 8 times the mass of the silane coupling agent, and the mass concentration of the ethanol aqueous solution is 8% to 12%; or / and, in step S1, the stirring time is 30 min to 60 min.
8. The temperature-controlled self-polymerizing sand-fixing proppant according to claim 6 or 7, characterized in that... In step S2, the heating temperature is 80°C to 90°C, and the pH of the mixture is adjusted to 4.0 to 4.5 with acetic acid; or / and, in step S2, the stirring speed is 500 r / min to 600 r / min, the stirring time is 2 h to 4 h, and the standing time is 7 h to 9 h.
9. The temperature-controlled self-polymerizing sand-fixing proppant according to claim 6, 7, or 8, characterized in that... In step S3, the stirring speed is 300 r / min to 350 r / min, the pH value during the reaction is 6 to 7, the reaction temperature is 60℃ to 80℃, the reaction time is 4h to 6h, and the holding time is 1h to 3h.
10. A method for preparing a temperature-controlled self-polymerizing sand-fixing proppant according to any one of claims 1 to 5, 7 to 9, characterized in that... Perform it as follows: S1, add the required amount of surfactant to the ethanol aqueous solution, then add the required amount of proppant and stir to obtain a mixture; S2, after heating the mixture, the pH value of the mixture is adjusted, the mixture is stirred and allowed to stand to react, and the reaction product is obtained. After filtering and drying the reaction product, the modified proppant is obtained. S3, under a nitrogen atmosphere, the required amount of modified proppant, temperature-sensitive material and initiator are added to an organic solvent and stirred to carry out a polymerization reaction. After the reaction is completed, the temperature is maintained, and after filtration and drying, a temperature-controlled self-polymerizing sand-fixing proppant is obtained.