Micro-fluidic chip for basalt CO2 mineralization reaction and preparation method

Abstract

The invention discloses a micro-fluidic chip for basalt CO2 mineralization reaction and a preparation method, the micro-fluidic chip comprises a bottom glass plate, a middle epoxy resin layer and a top glass plate, the preparation process comprises the following steps: installing a metal injection / outpouring pipeline on the bottom glass plate drilled with corresponding bolt holes, and forming an accommodating cavity by using a sealing ring; preparing and screening basalt particles according to the particle size distribution of a target reservoir, and filling the accommodating cavity with the basalt particles; quantitatively analyzing a particle arrangement structure based on a digital image processing technology, ensuring that the geometric similarity between the particle arrangement structure and a target reservoir is greater than or equal to 90%, and if the particle arrangement structure does not reach the standard, refilling; after the verification is passed, covering a top glass plate and pressing by using a bolt; and finally, pouring epoxy resin and sealing to form the micro-fluidic chip. The chip can bear high temperature and high pressure, supports visual observation and quantitative analysis of CO2 mineralization reaction in a deep geological environment, has high-precision pore reproduction, long-period sealing performance and high preparation efficiency, and is suitable for interdisciplinary research in the fields of energy environment and geophysics.

Description

Technical Field

[0001] This invention relates to the field of microfluidic control technology, specifically to a microfluidic chip and its preparation method for studying basalt-CO2 mineralization reaction under high temperature and high pressure conditions. Background Technology

[0002] In the study of CO2 geological sequestration technology in basalt, the realistic simulation of the mineralization reaction process is crucial, but the existing technology system has significant limitations, specifically in the following three aspects: (1) Existing studies mostly rely on offline sampling or non-transparent reactors, which can only perform intermittent imaging through equipment such as CT and MRI. Their time resolution is low, the equipment cost is high, and they cannot be compatible with high temperature, high pressure, and acidic environments, making it difficult to dynamically monitor the real-time dynamic processes of CO2 dissolution front migration, secondary mineral nucleation and growth, and multiphase fluid competitive transport at the pore scale.

[0003] (2) Microfluidic technology provides a new approach for dynamic monitoring of mineralization processes, but conventional microfluidic materials and structural designs are difficult to simulate real reaction environments. For example, traditional PDMS chips cannot meet the high temperature and high pressure conditions for basalt storage due to their poor temperature resistance and the tendency of the flow channel to deform and peel off under high pressure. While glass-based etched chips have better pressure resistance, their regular and smooth pores are significantly different from the natural rough surface and multi-level interconnected structure of basalt. More importantly, the chemically active surfaces of glass materials and basalt mineral components (such as calcium iron magnesium silicates) are completely different, making it impossible to simulate the CO2-mineral interface dissolution-precipitation reaction.

[0004] (3) Although embedding basalt thin slices into chips can preserve some of the natural pore characteristics, the preparation of thin slices requires a precise cutting and polishing process, which is time-consuming and has a low yield. Moreover, the random distribution of microcracks and the heterogeneity of mineral composition in the thin slices result in poor experimental repeatability, making it impossible to systematically quantify the influence of different pore morphologies (pore-throat ratio, tortuosity) and mineral types (calcium / magnesium silicate ratio) on the CO2 mineralization rate and secondary mineral precipitation path, which seriously restricts the in-depth study of basalt-CO2 mineralization reaction kinetics. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a microfluidic chip for CO2 mineralization reaction of basalt and its preparation method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A microfluidic chip for CO2 mineralization reaction of basalt includes a bottom glass plate, a middle epoxy resin layer, and a top glass plate stacked sequentially from bottom to top. The bottom glass plate, the middle epoxy resin layer, and the top glass plate are compressed and encapsulated by multiple sets of connectors. The middle epoxy resin layer has a accommodating cavity filled with basalt particles. The middle epoxy resin layer also has a metal injection pipe and a metal discharge pipe embedded in it. The bottom glass plate has an injection port and an injection outlet. One end of the metal injection pipe is connected to the injection port and the other end is connected to the accommodating cavity. One end of the metal discharge pipe is connected to the injection outlet and the other end is also connected to the accommodating cavity.

[0007] This microfluidic chip for CO2 mineralization reaction in basalt has been improved by modifying the central epoxy resin layer and the overall encapsulation structure, making it able to withstand high temperature and high pressure. It supports the visualization and quantitative analysis of CO2 mineralization reaction in deep geological environments, and has the advantages of high-precision pore reproduction, long-term sealing and high-efficiency preparation. It is suitable for interdisciplinary research in the fields of energy, environment and geophysics. Moreover, the entire microfluidic chip has a simple structure, is easy to manufacture, has controllable structural parameters, and has strong compatibility.

[0008] This microfluidic chip adopts a three-layer composite packaging structure and is sealed by axial compression and epoxy resin curing, giving it good high temperature and high pressure resistance. It can operate stably for a long time in high temperature, high pressure and corrosive environments. By filling graded basalt particles, the natural rough surface of basalt is completely preserved, which can realize high-fidelity reproduction of multi-scale pore networks and directly reproduce the dissolution-precipitation reaction process of CO2 in real basalt pores, significantly improving the realism of mineralization reaction simulation.

[0009] Furthermore, the connector is a bolt that connects the bottom glass plate, the middle epoxy resin layer, and the top glass plate, and the bolt is at least two bolts arranged diagonally.

[0010] Furthermore, the bottom glass plate and the top glass plate are each made of 2-5mm thick sapphire glass.

[0011] Furthermore, the central epoxy resin layer is a high-transmittance epoxy resin that can withstand temperatures above 150°C.

[0012] Furthermore, the bottom glass plate has an injection port and an injection outlet pre-set on its diagonal, and the diameters of the injection port and the injection outlet are 1 to 2 mm, respectively.

[0013] Furthermore, the metal injection pipe and the metal discharge pipe are respectively Hastelloy tubes embedded in the central epoxy resin layer, the outer diameter of the Hastelloy tubes being 1-2 mm and the wall thickness being 0.2-0.3 mm.

[0014] Furthermore, a sealing ring is provided on the inner circumference of the accommodating cavity, and the basalt particles are loaded within the area enclosed by the sealing ring.

[0015] Furthermore, the sealing ring is made of modified PTFE material with a diameter of 10-15 mm and a wire diameter of 1-1.5 mm.

[0016] Furthermore, the arrangement structure of the basalt particles has a geometric similarity of no less than 90% with that of the target reservoir.

[0017] A method for preparing a microfluidic chip for CO2 mineralization reaction of basalt, the method comprising the following steps: Prepare the bottom glass plate and the top glass plate, and drill a number of corresponding bolt connection holes along the diagonal of the bottom glass plate and the top glass plate respectively; The metal injection pipe, the injection port, and the injection outlet of the metal discharge pipe are connected on the bottom glass plate, and the receiving cavity is formed using a sealing ring. Basalt particle loading: Basalt particles are prepared according to the target reservoir particle size distribution curve, and mixed particle samples are obtained by graded sieving. The obtained mixed particle samples are then filled into the accommodating cavity. The structure of the filled basalt particles is verified. The arrangement structure of the basalt particles is quantitatively analyzed based on digital image processing technology to ensure that the geometric similarity with the target reservoir is ≥90%. If the standard is not met, the basalt particle loading step is repeated. The top glass plate is tightly attached to the sealing ring, and axial compression and sealing are achieved by bolts passing through the bolt connection holes. Finally, the middle epoxy resin layer is cast using a silicone mold to achieve the sealing of the microfluidic chip.

[0018] Compared with existing technologies, the beneficial effects of this invention are: 1. This microfluidic chip for basalt CO2 mineralization reaction improves the central epoxy resin layer and overall encapsulation structure, enabling it to withstand high temperature and pressure. It supports the visualization and quantitative analysis of CO2 mineralization reactions in deep geological environments, and combines high-precision pore reproduction, long-term sealing, and high-efficiency preparation, making it suitable for interdisciplinary research in the fields of energy, environment, and geophysics; 2. The entire microfluidic chip has a simple structure, is easy to manufacture, has controllable structural parameters, and strong compatibility; 3. This microfluidic chip adopts a three-layer composite encapsulation structure and is sealed by axial compression and epoxy resin curing, giving it good high-temperature and high-pressure resistance. It can operate stably for a long time in high-temperature, high-pressure, and corrosive environments; by filling graded basalt particles, it completely preserves... The naturally rough surface of basalt allows for high-fidelity reproduction of multi-scale pore networks, directly replicating the dissolution-precipitation reaction process of CO2 in real basalt pores, significantly improving the realism of mineralization reaction simulation; 4. By setting the accommodating cavity in the central epoxy resin layer, basalt particles can be directly loaded by filling, which not only preserves the natural porosity characteristics of basalt but also avoids the processing of basalt flaky materials, greatly reducing the difficulty of preparation, reducing production time, and improving the yield; 5. By arranging the basalt particles by loading, the influence of different pore morphologies and mineral types on the CO2 mineralization rate and secondary mineral precipitation path can be systematically quantified, making the experiment more repeatable and conducive to in-depth research on the kinetics of basalt-CO2 mineralization reaction. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of a microfluidic chip for CO2 mineralization reaction of basalt according to the present invention. Figure 2 This is a schematic diagram of the structure of the bottom glass plate of the microfluidic chip of the present invention; Figure 3 This is a schematic diagram of the epoxy resin layer in the middle of the microfluidic chip of the present invention; Figure 4 This is a schematic diagram of the structure of the top glass plate of the microfluidic chip of the present invention; Figure 5 This is a schematic diagram of the arrangement of basalt particles in the microfluidic chip of the present invention; In the diagram: 1. Bottom glass plate; 2. Middle epoxy resin layer; 3. Top glass plate; 4. Receptacle cavity; 5. Basalt particles; 6. Metal injection pipe; 7. Metal discharge pipe; 8. Injection port; 9. Injection outlet; 10. Bolt; 11. Bolt connection hole; 12. Sealing ring. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] As described in the background section, current research on CO2 geological sequestration in basalt faces three major technical bottlenecks: First, traditional experimental setups rely on intermittent detection methods such as offline CT / MRI, making it difficult to achieve real-time monitoring of the dynamic process of CO2 dissolution and mineral reaction at the pore scale. Second, although microfluidic technology provides a new approach for dynamic monitoring, it is limited by material properties: traditional PDMS chips have poor temperature and pressure resistance, and glass-based etched chips differ significantly from the natural rough structure and active mineral surface of basalt, making it impossible to truly simulate the CO2-mineral interface reaction. Further improved rock thin-section integration schemes, while partially retaining real pore characteristics, suffer from complex thin-section preparation processes and prominent mineral heterogeneity, resulting in poor experimental repeatability and difficulty in systematically quantifying the influence of pore morphology (pore-throat ratio, tortuosity) and mineral composition on the mineralization reaction, severely restricting the study of mineralization reaction kinetics. This invention provides a microfluidic chip for basalt CO2 mineralization reactions that overcomes the above problems, and Example 2 provides a method for preparing this microfluidic chip.

[0023] Example 1

[0024] like Figures 1-5 As shown, a microfluidic chip for basalt CO2 mineralization reaction includes a bottom glass plate 1, a middle epoxy resin layer 2, and a top glass plate 3 stacked sequentially from bottom to top. The bottom glass plate 1, the middle epoxy resin layer 2, and the top glass plate 3 are sealed together by multiple sets of connectors. The middle epoxy resin layer 2 has a cavity 4 filled with basalt particles 5. The middle epoxy resin layer 2 also has a metal injection pipe 6 and a metal discharge pipe 7 embedded in it. The bottom glass plate 1 has an injection port 8 and an injection outlet 9. One end of the metal injection pipe 6 is connected to the injection port 8 and the other end is connected to the cavity 4. One end of the metal discharge pipe 7 is connected to the injection outlet 9 and the other end is also connected to the cavity 4.

[0025] This microfluidic chip for CO2 mineralization reaction in basalt has been improved by modifying the central epoxy resin layer and the overall encapsulation structure, making it able to withstand high temperature and high pressure. It supports the visualization and quantitative analysis of CO2 mineralization reaction in deep geological environments, and has the advantages of high-precision pore reproduction, long-term sealing and high-efficiency preparation. It is suitable for interdisciplinary research in the fields of energy, environment and geophysics. Moreover, the entire microfluidic chip has a simple structure, is easy to manufacture, has controllable structural parameters, and has strong compatibility.

[0026] This microfluidic chip adopts a three-layer composite packaging structure and is sealed by axial compression and epoxy resin curing, giving it good high temperature and high pressure resistance. It can operate stably for a long time in high temperature, high pressure and corrosive environments. By filling it with graded basalt particles 5, the natural rough surface of basalt is completely preserved, which can realize high-fidelity reproduction of multi-scale pore networks and directly reproduce the dissolution-precipitation reaction process of CO2 in real basalt pores, significantly improving the realism of mineralization reaction simulation.

[0027] By setting the accommodating cavity 4 in the central epoxy resin layer 2, the basalt particles 5 can be directly loaded by filling. This not only preserves the natural porosity characteristics of basalt but also avoids the processing of basalt flaky materials, greatly reducing the difficulty of preparation, shortening production time, and improving the yield. Moreover, by arranging the basalt particles by loading, the influence of different pore morphologies (pore-throat ratio, tortuosity) and mineral types (calcium / magnesium silicate ratio) on the CO2 mineralization rate and secondary mineral precipitation path can be systematically quantified. This results in better experimental repeatability and is conducive to in-depth research on the kinetics of basalt-CO2 mineralization reaction.

[0028] The microfluidic chip is fabricated using the bottom glass plate 1, the middle epoxy resin layer 2, and the top glass plate 3, making it transparent and visible, which is beneficial for visual observation.

[0029] By utilizing the pre-embedded metal injection pipe 6 and metal discharge pipe 7, which are connected to the preset injection port 8 and discharge port 9, channels are avoided between layers, resulting in better sealing between layers. The openings of the injection port and discharge port also facilitate connection to input and output pipelines in subsequent experiments.

[0030] Furthermore, the connecting component is a bolt 10 that connects the bottom glass plate 1, the middle epoxy resin layer 2, and the top glass plate 3, and the bolt 10 is at least two located diagonally. The connection using bolts 10 greatly enhances the connection strength between the three components, and the connection is simple and convenient.

[0031] Furthermore, the bottom glass plate 1 and the top glass plate 3 are respectively made of sapphire glass with a thickness of 2 to 5 mm, preferably 3 mm.

[0032] Furthermore, the central epoxy resin layer 2 is made of modified high-temperature resistant (≥150℃) high-transmittance epoxy resin, and the bolts are made of 316L stainless steel.

[0033] Furthermore, the bottom glass plate 1 has an injection port 8 and an injection outlet 9 pre-set on its diagonal, the diameter of the injection port 8 and the injection outlet 9 being 1 to 2 mm, preferably 1.5 mm.

[0034] Furthermore, the metal injection pipe 6 and the metal discharge pipe 7 are both Hastelloy alloy pipes pre-embedded in the central epoxy resin layer 2. The Hastelloy alloy pipes have an outer diameter of 1-2 mm and a wall thickness of 0.2-0.3 mm, preferably an outer diameter of 1 mm and a wall thickness of 0.2 mm. Using the Hastelloy alloy pipes as injection and discharge pipes not only provides good strength and corrosion resistance but also prevents leakage of liquids and gases.

[0035] In this embodiment, the bottom glass plate 1, the middle epoxy resin layer 2, and the top glass plate 3 are all rectangular plates, and the accommodating cavity 4 is also a rectangular structure. The metal injection channel 6 and the metal discharge channel 7 are arranged on one diagonal of the microfluidic chip, while the bolts 10 are distributed on the other diagonal. This arrangement allows for a larger accommodating cavity within the rectangular chip, while also making full use of the remaining space for connectors and channels, thus miniaturizing the overall chip size while ensuring experimental requirements.

[0036] Furthermore, a sealing ring 12 is provided on the inner circumference of the accommodating cavity 4, and the basalt particles 5 are loaded within the area enclosed by the sealing ring 12.

[0037] The sealing ring 12 not only serves as a seal to prevent the poured epoxy resin from entering the reaction area, but also keeps the mineralization reaction within the area enclosed by the sealing ring. Combined with the metal injection pipe and the metal discharge pipe, this ensures that substances participating in the reaction, such as liquids, gases, and basalt particles, do not directly contact the epoxy resin, reducing the impact on the experiment.

[0038] Furthermore, the sealing ring is made of modified PTFE material, with a diameter of 15mm and a wire diameter of 1.5mm.

[0039] Furthermore, the arrangement structure of the basalt particles 5 has a geometric similarity of no less than 90% with that of the target reservoir.

[0040] Furthermore, the middle epoxy resin layer 2 between the bottom glass plate 1 and the top glass plate 3 is formed by integral casting and curing, ensuring the sealing between layers and further improving the connection strength and stability of the entire chip. After the experiment, the chip can be opened with a desorbent, refilled with basalt particles, repackaged, and reused.

[0041] Example 2

[0042] This embodiment provides a method for preparing the microfluidic chip used in the CO2 mineralization reaction of basalt as described in Embodiment 1. The preparation method includes the following steps: Step 1: Prepare a rectangular bottom glass plate 1 and a circular top glass plate 3, and drill a number of corresponding bolt connection holes 11 along the diagonal of the bottom glass plate 1 and the radial diagonal of the top glass plate 3, respectively.

[0043] Step 2: Connect the metal injection pipe 6 and the injection port 8, as well as the metal discharge pipe 7 and the discharge port 9 on the bottom glass plate 1, and form the receiving cavity 4 using the sealing ring 12.

[0044] Step 3: Loading basalt particles: Prepare basalt particles 5 according to the target reservoir particle size distribution curve, obtain mixed particle samples by graded sieving, and then fill the cavity 4 with the obtained mixed particle samples.

[0045] Step 4: Verify the structure of the filled basalt particles. Quantitatively analyze the arrangement structure of the basalt particles based on digital image processing technology to ensure that the geometric similarity with the target reservoir is ≥90%. If the standard is not met, repeat the basalt particle loading step.

[0046] Step 5: The top glass plate is tightly attached to the sealing ring, and axial compression and sealing are achieved by bolts passing through the bolt connection holes. Finally, the middle epoxy resin layer is cast using a silicone mold to achieve the sealing of the microfluidic chip.

[0047] The above method enables the relatively convenient fabrication of microfluidic chips for basalt CO2 mineralization reactions. These microfluidic chips overcome temperature and pressure tolerance limitations through a multi-layer composite encapsulation structure. They utilize in-situ encapsulation of basalt particles to preserve the natural rock morphology and active mineral surfaces. Combined with particle gradation screening, they achieve high-fidelity reproduction of multi-scale pore networks. This supports real-time observation and quantitative analysis of the dynamic process of CO2 dissolution and mineral reaction under high temperature, high pressure, and acidic conditions, providing key technical means for revealing the kinetic mechanism of basalt-CO2 mineralization reactions.

[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A microfluidic chip for CO2 mineralization reaction of basalt, characterized in that, The device comprises a bottom glass plate, a middle epoxy resin layer, and a top glass plate stacked sequentially from bottom to top. The bottom glass plate, the middle epoxy resin layer, and the top glass plate are pressed and sealed together by multiple sets of connectors. The middle epoxy resin layer has a receiving cavity filled with basalt particles. The middle epoxy resin layer also has a metal injection pipe and a metal discharge pipe embedded in it. The bottom glass plate has an injection port and an injection outlet. One end of the metal injection pipe is connected to the injection port and the other end is connected to the receiving cavity. One end of the metal discharge pipe is connected to the injection outlet and the other end is also connected to the receiving cavity.

2. The microfluidic chip for basalt CO2 mineralization reaction according to claim 1, characterized in that, The connector is a bolt that connects the bottom glass plate, the middle epoxy resin layer and the top glass plate, and the bolt is at least two bolts arranged diagonally.

3. The microfluidic chip for basalt CO2 mineralization reaction according to claim 1, characterized in that, The bottom glass plate and the top glass plate are both made of sapphire glass with a thickness of 2 to 5 mm.

4. The microfluidic chip for basalt CO2 mineralization reaction according to claim 1, characterized in that, The central epoxy resin layer is a high-transmittance epoxy resin that can withstand temperatures above 150°C.

5. The microfluidic chip for basalt CO2 mineralization reaction according to claim 1, characterized in that, The bottom glass plate has an injection port and an injection outlet pre-set on its diagonal, and the diameters of the injection port and the injection outlet are 1 to 2 mm, respectively.

6. The microfluidic chip for basalt CO2 mineralization reaction according to claim 1, characterized in that, The metal injection pipe and the metal discharge pipe are respectively Hastelloy alloy pipes embedded in the middle epoxy resin layer, with an outer diameter of 1-2 mm and a wall thickness of 0.2-0.3 mm.

7. The microfluidic chip for basalt CO2 mineralization reaction according to claim 1, characterized in that, The accommodating cavity is provided with a sealing ring on its inner circumference, and the basalt particles are loaded within the area enclosed by the sealing ring.

8. The microfluidic chip for basalt CO2 mineralization reaction according to claim 7, characterized in that, The sealing ring is made of modified PTFE material with a diameter of 10-15 mm and a wire diameter of 1-1.5 mm.

9. The microfluidic chip for basalt CO2 mineralization reaction according to claim 1, characterized in that, The arrangement of the basalt particles has a geometric similarity of no less than 90% with that of the target reservoir.

10. The method for preparing a microfluidic chip for basalt CO2 mineralization reaction according to any one of claims 1 to 9, characterized in that, The preparation method includes the following steps: Prepare the bottom glass plate and the top glass plate, and drill a number of corresponding bolt connection holes along the diagonal of the bottom glass plate and the top glass plate respectively; The metal injection pipe, the injection port, and the injection outlet of the metal discharge pipe are connected on the bottom glass plate, and the receiving cavity is formed using a sealing ring. Basalt particle loading: Basalt particles are prepared according to the target reservoir particle size distribution curve, and mixed particle samples are obtained by graded sieving. The obtained mixed particle samples are then filled into the accommodating cavity. The structure of the filled basalt particles is verified. The arrangement structure of the basalt particles is quantitatively analyzed based on digital image processing technology to ensure that the geometric similarity with the target reservoir is ≥90%. If the standard is not met, the basalt particle loading step is repeated. The top glass plate is tightly attached to the sealing ring, and axial compression and sealing are achieved by bolts passing through the bolt connection holes. Finally, the middle epoxy resin layer is cast using a silicone mold to achieve the sealing of the microfluidic chip.

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