Modified nano-silica-graphene oxide double-particle composite hydrogel, and preparation method and application thereof
Patent Information
- Application Number
- CN202311511665.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-14
- Publication Date
- 2026-09-29
- Estimated Expiration
- 2043-11-14
AI Technical Summary
[0004]本发明公开了一种改性纳米二氧化硅-氧化石墨烯双颗粒复合水凝胶及其制备方法和应用；本发明通过向传统的氧化石墨烯改性聚丙烯酰胺凝胶中加入醛基改性的nmSiO2，不仅解决了nmSiO2容易团聚和分散稳定性差的缺点，而且改变了凝胶的流变性、增强了机械强度，使其适用于更加复杂的储层环境
[0019]本发明通过向丙烯酰胺(AAM)和聚乙烯亚胺(PEI)凝胶体系中掺杂醛基修饰的nmSiO2-氧化石墨烯不仅加快了凝胶的成胶速度，而且缩短了凝胶的成胶时间，提高了凝胶的热稳定性；同时也使凝胶的流变性能改变，增强了凝胶的黏弹性、屈服应力及蠕变-回复性能，增强了凝胶的机械强度，进而提高聚丙烯酰胺凝胶的适用范围，克服了油田使用的常规凝胶的局限性。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of oilfield water shut-off and profile control technology, specifically to a modified nano-silica-graphene oxide dual-particle composite hydrogel, its preparation method, and its application. Background Technology
[0002] After years of water-drive development, my country's low-permeability oil and gas fields are now in the mid-to-late stages of development, with extremely high water content in the oil reservoirs and extremely low crude oil recovery rates. Therefore, effectively sealing formation water, reducing the water content of produced fluids, and increasing oil production have become critical technical issues that urgently need to be addressed in my country's major oilfields. Gel-based water shut-off and profile control is a widely used technique in oilfields to improve oil recovery. It involves placing a gel in a high-permeability, water-flooded formation near the wellbore to reduce the permeability of the target layer to the oil-displacing fluid, thereby altering the flow profile and diverting the injected high-pressure water drive to areas in the oil well with higher residual oil content that were not affected by the water flow, ultimately improving oil recovery. Among gel-based water shut-off and profile control agents, polyacrylamide hydrogel is particularly advantageous due to its simple preparation, low cost, and high overall efficiency, and is widely used in oilfield development for profile control and water shut-off to reduce water production and thus improve oil recovery. Polyacrylamide gel systems are mainly composed of macromolecular polymers and crosslinking agents. The crosslinking agent molecules connect two adjacent macromolecular polymer molecules, and through numerous intermolecular reactions similar to association, a three-dimensional network structure is ultimately formed at the microscopic level. Due to this unique microscopic three-dimensional network structure, polyacrylamide gels exhibit a solid-like shape at the material level.
[0003] Existing gel water-blocking agents can basically meet the needs of water-blocking agents under various reservoir conditions. However, due to increasingly demanding oil production conditions, varieties that can meet certain special requirements, such as high-temperature resistance, high salinity, hard water resistance, and high strength, remain relatively scarce. Many gels have low performance and lack sufficient strength to be suitable for complex oil formations. Furthermore, due to the large quantities of gel water-blocking agents used, only inexpensive gels are worthwhile. Currently, many high-performance gels are expensive and unsuitable for extraction. Because of the extremely large quantities used, many current gel products require the addition of environmentally harmful substances, which can easily cause large-scale environmental pollution. Therefore, researching a high-performance, low-cost, and environmentally friendly gel for sealing formation water, reducing the water content of produced fluids, and improving oil recovery has become an urgent problem to be solved. Summary of the Invention
[0004] This invention discloses a modified nano-silica-graphene oxide dual-particle composite hydrogel, its preparation method, and its application. By adding aldehyde-modified nmSiO2 to traditional graphene oxide-modified polyacrylamide gel, this invention not only solves the shortcomings of nmSiO2's easy aggregation and poor dispersion stability, but also changes the rheological properties of the gel and enhances its mechanical strength, making it suitable for more complex reservoir environments.
[0005] The present invention first provides a modified nano-silica-graphene oxide biparticle composite hydrogel, which is made from raw materials comprising the following components: graphene oxide, acrylamide, polyacrylamide, modified nano-silica, polyethyleneimine, initiator and water;
[0006] Based on the total mass of water, the composition includes: graphene oxide 0.2 wt.%–5.0 wt.%, acrylamide 5.0 wt.%–15.0 wt.%, polyacrylamide 0.1 wt.%–1.0 wt.%, modified nano-silica 0.2 wt.%–3 wt.%, polyethyleneimine 0.1 wt.%–0.5 wt.%, and initiator 0.01 wt.%–0.12 wt.%.
[0007] The modified nano-silica-graphene oxide dual-particle composite hydrogel described above, wherein the modified nano-silica is aldehyde-modified nano-silica; specifically, it may be acrolein-modified nano-silica.
[0008] The initiator is azobisisobutyronitrile or potassium persulfate (KPS).
[0009] The modified nano-silica-graphene oxide biparticle composite hydrogel described above contains, by total mass of water, 0.2 wt.% graphene oxide, 10 wt.% acrylamide, 0.3 wt.% polyacrylamide, 0.5 wt.% modified nano-silica, 0.2 wt.% polyethyleneimine, and 0.02 wt.% initiator.
[0010] The preparation method of the aldehyde-modified nano-silica is a commonly used method in the art, and specifically includes the following steps: styrene, water, potassium persulfate and allyltriethoxysilane are mixed and reacted under an inert atmosphere (specifically, the reaction temperature is 80°C). After the reaction, the mixture is cooled to room temperature, and then acrolein solution and potassium persulfate solution are added. The reaction is carried out under an inert atmosphere (specifically, the reaction temperature is 80°C). After the reaction, the mixture is centrifuged and washed. The centrifuged liquid is separated into layers, the supernatant is removed, and the remaining liquid is vacuum dried to obtain the aldehyde-modified nano-silica.
[0011] This invention also provides a method for preparing the above-mentioned modified nano-silica-graphene oxide biparticle composite hydrogel, comprising the following steps:
[0012] The graphene oxide, acrylamide, polyacrylamide, modified nano-silica, and polyethyleneimine were mixed in water, and the initiator was added under an inert atmosphere to carry out the reaction, thereby obtaining the modified nano-silica-graphene oxide dual-particle composite hydrogel.
[0013] In the above preparation method, the reaction temperature is 80-140℃ and the time is 24-96h.
[0014] Specifically, the reaction temperature is 120°C and the reaction time is 48 hours.
[0015] In the above preparation method, the temperature of the system when the initiator is added is 60-65°C; specifically, it can be 60°C.
[0016] The inert atmosphere is a nitrogen or argon atmosphere.
[0017] Finally, this invention provides the application of the above-mentioned modified nano-silica-graphene oxide dual-particle composite hydrogel in oil and gas fields to enhance oil recovery.
[0018] Alternatively, the modified nano-silica-graphene oxide dual-particle composite hydrogel described above can be used as a water shut-off and profile control agent in oil and gas fields.
[0019] This invention accelerates the gelation rate and shortens the gelation time by doping aldehyde-modified nmSiO2-graphene oxide into an acrylamide (AAM) and polyethyleneimine (PEI) gel system, thereby improving the thermal stability of the gel. Simultaneously, it alters the rheological properties of the gel, enhancing its viscoelasticity, yield stress, and creep-recovery properties, as well as its mechanical strength. This expands the applicability of polyacrylamide gels and overcomes the limitations of conventional gels used in oil fields. Attached Figure Description
[0020] Figure 1 Photograph of the modified nano-silica-graphene oxide biparticle composite hydrogel prepared in Example 1.
[0021] Figure 2 The image shows a scanning electron microscope (SEM) image of the microstructure of the modified nano-silica-graphene oxide biparticle composite hydrogel prepared in Example 1.
[0022] Figure 3 The image shows a magnified scanning electron microscope (SEM) image of the microstructure of the modified nano-silica-graphene oxide biparticle composite hydrogel prepared in Example 1.
[0023] Figure 4The storage modulus (G')-frequency (f) curves and the energy dissipation modulus (G")-frequency (f) curves of GO gel and the modified nano-silica-graphene oxide biparticle composite hydrogel prepared in Example 1 are shown.
[0024] Figure 5 This is a comparative analysis of the creep-recovery properties of the gel.
[0025] Figure 6 The yield stress measurement curves of modified nano-silica-graphene oxide biparticle composite hydrogels prepared with different GO contents.
[0026] Figure 7 DSC images of modified nano-silica-graphene oxide biparticle composite hydrogels prepared with different GO contents. Detailed Implementation
[0027] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.
[0028] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.
[0029] In the quantitative experiments in the following examples, three replicate experiments were set up, and the average value of the results was taken.
[0030] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.
[0031] The allyltriethoxysilane used in the following examples was purchased from Aladdin, catalog number A151274.
[0032] Example 1
[0033] (1) Preparation of modified nano-silica (nmSiO2)
[0034] Add 25g of styrene (ST), 100mL of ultrapure water, and 0.1g of potassium persulfate to a 500mL three-necked flask equipped with a ring condenser. Heat the flask in a constant-temperature water bath to 70°C, ensuring uniform magnetic stirring at a constant speed of 400rpm during heating. Once the temperature has stabilized at 70°C, slowly add 25mL of allyltriethoxysilane dropwise to the shoulder of the vortex in the solution, maintaining a uniform addition rate to ensure complete dissolution of the reagent in the mixture. Immediately after the addition is complete, purge the flask with a suitable amount of nitrogen gas to remove air, and then heat the flask at a constant temperature of 80°C for 7 hours under a nitrogen atmosphere. After the above experimental steps are completed, turn off the heating switch and cool to room temperature. Then, add 20 mL of 98% acrolein aqueous solution evenly to the three-necked flask while adjusting the rotation speed to 200 rpm. Since air will enter the apparatus during the addition of acrolein, it is necessary to introduce an appropriate amount of nitrogen gas again to purge the air. After that, add 0.3 mL of 85% potassium persulfate solution and raise the temperature to 80°C. React under nitrogen protection for 8 hours.
[0035] After the reaction was complete, the resulting mixed solution was centrifuged (centrifugation speed adjusted to 4000 rpm), with each centrifugation time controlled at 0.5 h. The mixed solution was washed three times sequentially with toluene and ethanol. After centrifugation, the centrifuged liquid was allowed to stand until it separated into layers. Then, the supernatant (mainly toluene and ethanol) was separated, and the remaining liquid was placed in a beaker and sealed with plastic wrap. It was then vacuum dried at 80 °C for 22–24 h. After vacuum drying, the sample was removed from the drying oven, the plastic wrap was removed, and after cooling to room temperature, the prepared modified nmSiO2 was gently scraped off the beaker wall with a spatula and transferred to a clean reagent bottle for later use.
[0036] (2) Preparation of modified nano-silica-graphene oxide biparticle composite hydrogel
[0037] First, 200 mL of a 2 mg / mL GO (graphene oxide) aqueous solution was added to a 500 mL beaker. Then, 10 wt.% acrylamide (AAM), 0.3 wt.% polyacrylamide (PAM), 0.5 wt.% modified nano-SiO2, and 0.2 wt.% polyethyleneimine (PEI) were added to the GO aqueous solution. The mixture was heated steadily under stirring and nitrogen protection. When the temperature reached 60 °C, 0.02 wt.% azobisisobutyronitrile (azobisisobutyronitrile) (initiator) was immediately added to the mixed solution. After magnetic stirring for 0.5 h, the mixture was poured into a beaker, and the remaining air in the beaker was replaced with nitrogen. The beaker was then sealed and placed in a constant temperature oven at 120 °C for 48 h. This yielded a modified nano-silica-graphene oxide biparticle composite hydrogel.
[0038] The mass percentages of acrylamide, polyacrylamide, modified nmSiO2, polyethyleneimine, and azobisisobutyronitrile mentioned above all refer to their mass percentages relative to the water in the system.
[0039] A photograph of the modified nano-silica-graphene oxide biparticle composite hydrogel prepared in this embodiment is shown below. Figure 1 See electron microscope image. Figure 2 .Depend on Figure 2 It can be seen that the GO sheets adhere to the backbone of the gel network molecular structure, and the polyacrylamide polymer gel exhibits a honeycomb structure. SiO2 particles can be observed attached to the gel network structure. (Magnified image) Figure 3 The molecular framework of the gel network structure is clearly visible. The network pore structure of the SiO2-added gel becomes more pronounced, and layering occurs. Through the first layer, the second, third, or even multiple layers of the network can be seen. The polymers intertwine to form the framework of the network pores, and the network pore size distribution is uniform. Comparison reveals that the network structure of the composite gel formed by adding modified nmSiO2 is more compact and stronger than that of the polymer gel without modified nmSiO2, which is consistent with the storage modulus curve.
[0040] Example 2, Gel Performance Test
[0041] Differential scanning calorimetry analysis using a NETZSCH STA409PC instrument from Germany revealed that the graphene oxide composite polyacrylamide gel without modified nmSiO2 (the only difference being that modified nmSiO2 was not added during the reaction, while the rest of the steps were the same as the gel preparation method in Example 1) showed that the complete dehydration temperature of the gel without modified nmSiO2 increased from 156℃ to over 178℃ compared to the gel with modified nmSiO2. This indicates that the gel exhibits stronger resistance to dehydration and degradation at high temperatures, and its thermal stability is significantly improved.
[0042] Rheological properties of the gel were measured using a TAARES-G2 rheometer (USA). The results showed that the modified nano-silica-graphene oxide biparticle composite hydrogel exhibited improved viscoelasticity, yield stress, and creep-recovery properties, while also demonstrating superior mechanical strength, ductility, and toughness. This invention successfully endows polyacrylamide gels with the excellent physical properties of graphene oxide and nanoparticles, improving the gel's plugging efficiency and potentially further enhancing oil recovery.
[0043] The preparation method of PAAm gel is the same as that of modified nano-silica-graphene oxide biparticle composite hydrogel in Example 1, except that modified nano-SiO2 and graphene oxide are not added.
[0044] GO gel (i.e.) Figure 5-7The preparation method of PAAm / 0.2wt.%GO gel is the same as the preparation method of modified nano-silica-graphene oxide biparticle composite hydrogel in Example 1, except that no modified nano-SiO2 is added.
[0045] Figure 4 The storage modulus (G')-frequency (f) relationship curves of GO gel and the modified nano-silica-graphene oxide biparticle composite hydrogel prepared in Example 1 ( Figure 4 The relationship curve between a) and energy dissipation modulus (G") and frequency (f) in the figure. Figure 4 (b) from Figure 4 It is not difficult to observe that after grafting nmSiO2 particles onto polyacrylamide gel, both its storage modulus and dissipation modulus are significantly improved. The storage modulus increases from 153.9 Pa (mean, the same below) to 2595 Pa, and the dissipation modulus increases from 39 Pa to 1684 Pa. This indicates that the strength of the graphene oxide polyacrylamide gel system grafted with nmSiO2 is greatly improved. This is due to the chemical bonding between the aldehyde groups grafted onto the nmSiO2 surface and the carbonyl groups on the graphene oxide, which further forms a stable three-dimensional (3D) network structure, thereby enhancing the viscoelasticity of the polyacrylamide gel system. Simultaneously, Figure 4 Both of the relationship curves show a linear change overall, indicating that the elasticity of the gel has a small range, good gelation effect, and high toughness, making it suitable for complex oil well formation environments.
[0046] Figure 4 In this context, GO / PAAm gel refers to the GO gel described above, and SiO2 / GO / PAAm gel refers to the modified nano-silica-graphene oxide biparticle composite hydrogel prepared in Example 1.
[0047] Figure 5 This is a comparative analysis of the creep-recovery properties of the gels. From... Figure 5 It is easy to observe that the GO gel exhibits a smaller compliance J during the creep stage from 27 to 150 s, indicating a smaller degree of deformation. In contrast, the gel grafted with nmSiO2 shows a larger compliance during this stage, indicating a greater degree of deformation. On the other hand, during the recovery stage after 150 s, the compliance variation range of the nmSiO2-grafted gel system is larger than that of the ungrafted nmSiO2 gel system, indicating a higher tensile strength. Therefore, nmSiO2 grafting enhances the creep-recovery properties of the gel and improves the rheological properties of the polyacrylamide gel system.
[0048] The yield stress measurement curve of the modified nano-silica-graphene oxide biparticle composite hydrogel is shown in the figure. Figure 6As shown in the figure, the yield stress of GO gel increases after adding modified nmSiO2 within a certain range.
[0049] The thermal stability of polymer gel systems can be studied by DSC testing. Figure 7 The DSC pattern of the modified nano-silica-graphene oxide biparticle composite hydrogel is shown. Figure 7 It is evident that PAAm gel exhibits the weakest thermal stability, undergoing dehydration at 156℃. GO gel demonstrates higher thermal stability than PAAm gel, and the addition of modified nmSiO2 further enhances the thermal stability of the hydrogel. This is primarily due to the abundance of hydroxyl groups on the surface of both GO and SiO2 particles. These hydroxyl groups can form hydrogen bonds with water molecules, thereby achieving a water-locking effect. This indicates that adding modified nmSiO2 particles to GO gel can not only regulate the mechanical properties of the hydrogel but also improve its temperature resistance, making it suitable for water shut-off requirements in high-temperature oil reservoirs.
[0050] Figures 5-7 The PAAm / 0.2wt.%GO / 0.5wt.%SiO2 gel is the modified nano-silica-graphene oxide biparticle composite hydrogel prepared in Example 1.
Claims
1. A modified nano-silica-graphene oxide biparticle composite hydrogel, which is made from raw materials comprising the following components: graphene oxide, acrylamide, polyacrylamide, modified nano-silica, polyethyleneimine, initiator and water; Based on the total mass of water, the composition includes: graphene oxide 0.2 wt.%~5.0 wt.%, acrylamide 5.0 wt.%~15.0 wt.%, polyacrylamide 0.1 wt.%~1.0 wt.%, modified nano-silica 0.2 wt.%~3 wt.%, polyethyleneimine 0.1 wt.%~0.5 wt.%, and initiator 0.01 wt.%~0.12 wt.%. The modified nano-silica is aldehyde-modified nano-silica; The method for preparing the aldehyde-modified nano-silica includes the following steps: mixing styrene, water, potassium persulfate and allyltriethoxysilane, reacting under an inert atmosphere at a reaction temperature of 80°C, cooling to room temperature after the reaction, then adding acrolein solution and potassium persulfate solution, reacting under an inert atmosphere at a reaction temperature of 80°C, centrifuging and washing after the reaction, separating the centrifuged liquid into layers, removing the supernatant, and vacuum drying the remaining liquid to obtain the aldehyde-modified nano-silica.
2. The modified nano-silica-graphene oxide dual-particle composite hydrogel according to claim 1, characterized in that: The initiator is azobisisobutyronitrile or potassium persulfate.
3. The modified nano-silica-graphene oxide dual-particle composite hydrogel according to claim 1 or 2, characterized in that: Based on the total mass of water, the composition includes 0.2 wt.% graphene oxide, 10 wt.% acrylamide, 0.3 wt.% polyacrylamide, 0.5 wt.% modified nano silica, 0.2 wt.% polyethyleneimine, and 0.02 wt.% initiator.
4. The preparation method of the modified nano-silica-graphene oxide dual-particle composite hydrogel according to any one of claims 1-3, comprising the following steps: The graphene oxide, acrylamide, polyacrylamide, modified nano-silica, and polyethyleneimine were mixed in water, and the initiator was added under an inert atmosphere to carry out the reaction, thereby obtaining the modified nano-silica-graphene oxide dual-particle composite hydrogel.
5. The preparation method according to claim 4, characterized in that: The reaction is carried out at a temperature of 80~140℃ for a time of 24~96h.
6. The preparation method according to claim 4 or 5, characterized in that: The system temperature is 60~65℃ when the initiator is added; The inert atmosphere is a nitrogen or argon atmosphere.
7. The application of the modified nano-silica-graphene oxide dual-particle composite hydrogel according to any one of claims 1-3 in enhancing oil and gas recovery in oil and gas fields.
8. The application of the modified nano-silica-graphene oxide dual-particle composite hydrogel according to any one of claims 1-3 as a water shut-off and profile control agent in oil and gas fields.