Microfluid fracture model and fracture reactive precipitation experiment device and method

Abstract

The invention discloses a microfluid crack model and a crack reactive precipitation experiment device and method, and relates to the technical field of crack precipitation experiments.The microfluid crack model comprises a glass slide, and a transparent rough crack body is fixedly arranged on the glass slide; the fluid mixing cavity is arranged at one end of the rough fracture main body and can inject different reaction fluids into the rough fracture main body; and the outlet cavity is fixedly arranged at the other end of the rough fracture main body and can be used for guiding out the reacted solution in the rough fracture main body. According to the crack reactive precipitation experiment device and method based on the microfluid crack model, visual observation of a crack reactive precipitation experiment can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of fracture precipitation experiments, and in particular to a microfluid fracture model, a fracture reactive precipitation experimental device and a method. Background Art

[0002] In underground environments, fractured media are the main channels for fluid flow and material transport. Mineral precipitation is a key process in underground environments. Mineral precipitation affects the geometric structure of fracture channels and thus changes the hydraulic properties of fractured media. Studying mineral precipitation patterns and mechanisms is of great significance to many geological processes.

[0003] At present, due to the opaque nature of natural rocks, it is difficult to achieve dynamic real-time visual observation and quantitative analysis of the sedimentation process in complex rock fissures. Therefore, it is urgent to design a technical solution that can realize the visual observation of fracture reactive precipitation experiments. Summary of the invention

[0004] The purpose of the present invention is to provide a microfluidic fracture model, a fracture reactive precipitation experimental device and a method to solve the problems existing in the above-mentioned prior art and to realize the visualized observation of the fracture reactive precipitation experiment.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a microfluidic fracture model, comprising:

[0007] A glass slide, on which a transparent rough crack body is fixed;

[0008] A fluid mixing chamber, which is arranged at one end of the rough fracture body and can inject different reaction fluids into the rough fracture body;

[0009] The outlet cavity is fixedly arranged at the other end of the rough fracture body and can guide the reacted solution in the rough fracture body out.

[0010] Preferably, a rough glass block is fixed on the glass slide, and symmetrically arranged acrylic blocks are fixedly connected to both sides of the rough glass block; the acrylic block and the rough glass block are fixedly bonded to the glass slide to form the rough crack body.

[0011] Preferably, the fluid mixing chamber comprises a transparent rectangular block, and two horizontally inclined reaction liquid inlets are provided on the rectangular block; the ends of the two reaction liquid inlets are both connected to the rough fracture body.

[0012] Preferably, a liquid inlet groove is provided at one end of the rectangular block, the liquid inlet groove is fixedly and sealedly connected with one end of the rough fracture body, and one end of the two reaction liquid inlets passes through the liquid inlet groove.

[0013] Preferably, the outlet cavity comprises a transparent rectangular block, one end of which is provided with a liquid outlet groove, the liquid outlet groove is fixedly and sealedly connected with one end of the rough fracture body away from the fluid mixing chamber, and a fluid outlet channel is provided at the end of the liquid outlet groove.

[0014] The present invention also provides a fracture reactive precipitation experimental device, comprising an injection module, a real-time imaging module, a pressure drop monitoring module and the microfluid fracture model as described above; the injection module is connected to the fluid mixing chamber through a pipeline with a valve, and can inject reactive fluid into the microfluid fracture model; the real-time imaging module is used for real-time imaging of the fracture reactive precipitation experiment, and the pressure drop monitoring module can monitor the fluid pressure at both ends of the rough fracture body.

[0015] Preferably, the injection module includes a first injection pump and a second injection pump; the first injection pump is provided with a first reaction liquid injector, the first reaction liquid injector is connected to a first three-way valve through a pipeline, the first three-way valve is connected to one of the reaction liquid inlets of the fluid mixing chamber through a pipeline, and a hydrochloric acid injector is connected to the third valve port of the first three-way valve; the second injection pump is provided with a second reaction liquid injector, the second reaction liquid injector is connected to a second three-way valve through a pipeline, the second three-way valve is connected to the second reaction liquid inlet of the fluid mixing chamber through a pipeline, and a deionized water injector is connected to the third valve port of the second three-way valve.

[0016] Preferably, the real-time imaging module includes a camera, which is arranged above the microfluidic fracture model and is electrically connected to a computer; the pressure drop monitoring module includes pressure sensors respectively arranged at the liquid inlet groove and the liquid outlet groove of the microfluidic fracture model through valves.

[0017] Preferably, it also includes an ion chromatograph and a waste liquid collection module, the waste liquid collection module includes a waste liquid collection bottle, and the fluid outlet channel of the outlet chamber is connected to the waste liquid collection bottle through a pipeline; the ion chromatograph can measure the cation concentration of the waste liquid in the waste liquid collection bottle.

[0018] The present invention also provides a crack reactive precipitation experimental method, comprising the following steps:

[0019] Step 1: remove the air in the rough fracture model, switch the second three-way valve to the deionized water injector, inject deionized water, and make the deionized water flow into the waste liquid collection bottle through the microfluidic fracture model. When the deionized water completely fills the microfluidic fracture model, stop injecting deionized water;

[0020] Step 2, inducing a precipitation reaction, adjusting the first three-way valve and the second three-way valve, switching to the first reaction liquid injector and the second reaction liquid injector respectively, adjusting the first injection pump and the second injection pump, so that the two reaction fluids are simultaneously injected into the cracks of the microfluidic crack model at a constant and same flow rate, and the two reaction fluids are mixed in the microfluidic crack model to induce a calcium carbonate precipitation reaction;

[0021] Step 3: Real-time visual monitoring: Turn on the camera to record the precipitation process in real time, and record the data of two pressure sensors at the same time to monitor the pressure drop caused by precipitation;

[0022] Step 4, completing the experiment, when the total injected reaction solution volume reaches the preset value, stop injecting the reaction solution, turn off the first injection pump and the second injection pump, turn off the camera, and the experiment is completed;

[0023] Step 5, quantitative analysis of the precipitate. After the experiment is completed, switch the first three-way valve to the hydrochloric acid syringe, inject the hydrochloric acid solution, and allow the hydrochloric acid solution to pass through the microfluidic fracture model to dissolve the precipitate. The waste liquid flows into the waste liquid collection bottle. After collecting the waste liquid, the cation concentration is measured using an ion chromatograph to inversely calculate the mass of the precipitate remaining in the fracture of the microfluidic fracture model.

[0024] Compared with the prior art, the present invention has achieved the following technical effects:

[0025] The microfluidic fracture models of the present invention are all made of transparent materials, so the experimental process in the rough fracture body can be observed and recorded in real time by a camera, and have the advantages of high acquisition frame rate, low equipment cost, and strong repeatability; through real-time monitoring of two pressure sensors and data acquisition by a computer, pressure drop monitoring during the precipitation process is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 is a schematic diagram of a microfluidic fracture model in one embodiment of the present invention;

[0028] Figure 2Schematic diagram of a fracture reactive precipitation experimental device in one embodiment of the present invention.

[0029] In the figure: 1-fluid mixing chamber, 2-first acrylic block, 3-second acrylic block, 4-rough glass block, 5-outlet chamber, 6-first reaction liquid inlet, 7-second reaction liquid inlet, 8-glass slide, 9-first reaction liquid syringe, 10-first injection pump, 11-second injection pump, 12-second reaction liquid syringe, 13-deionized water syringe, 14-second three-way valve, 15-first three-way valve, 16-first pressure sensor, 17-first valve, 18-microfluidic fracture model, 19-camera, 20-second pressure sensor, 21-second valve, 22-computer, 23-ion chromatograph, 24-waste liquid collection bottle, 25-hydrochloric acid syringe. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The purpose of the present invention is to provide a microfluidic fracture model, a fracture reactive precipitation experimental device and a method to solve the problems existing in the above-mentioned prior art and to realize the visualized observation of the fracture reactive precipitation experiment.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Mineral precipitation often involves a complex interaction between convection, diffusion and chemical reactions, and the pore geometry and mineral properties are heterogeneous, which makes the precipitation pattern and precipitate particle morphology complex and diverse. Studying different precipitation patterns and their influencing factors is of great significance for the study of mineral precipitation dynamics and the prediction of permeability evolution of geological structures.

[0034] Reactive precipitation experiments in fractured media known to the inventors mostly use simple parallel plate models and fracture network models, which are difficult to fully simulate the geometric characteristics of real fractures. Moreover, most of the experiments are conducted in a non-visual model, using CT scanning and X-rays to observe the precipitation behavior and distribution inside the fractures. The scanning time is long, the equipment cost is high, and it is impossible to achieve real-time observation of the dynamic process of precipitation. In addition, the repeatability and controllability of the experiment are poor. In order to solve the above problems, the present invention proposes a microfluidic fracture model, a fracture reactive precipitation experimental device and method, and produces a transparent microfluidic fracture model with a real geometric morphology. The model has the characteristics of short production cycle and low production cost. Specifically, Figure 1 As shown, the microfluidic fracture model 18 of the present invention includes a glass slide 8, on which a transparent rough fracture body is fixedly provided; a fluid mixing chamber 1 is arranged at one end of the rough fracture body, and different reaction fluids can be injected into the rough fracture body; an outlet chamber 5 is fixedly arranged at the other end of the rough fracture body, and the solution after the reaction in the rough fracture body can be discharged.

[0035] In a specific embodiment, a rough glass block 4 with a rough surface is fixed on a transparent glass slide 8 by glue. The required rough glass block 4 can be directly purchased on the market and can be used to make a microfluidic model after being cut into small pieces. The rough glass block 4 has the characteristics of simple production method, low cost and short production cycle. The two sides of the rough glass block 4 are fixedly connected with symmetrically arranged acrylic blocks by glue; the acrylic blocks and the rough glass block 4 are fixedly bonded to the glass slide 8 to form a rough crack body. The fluid mixing chamber 1 and the outlet chamber 5 are respectively made of rectangular blocks of acrylic material. The rectangular block of the fluid mixing chamber 1 is provided with two horizontally inclined reaction liquid inlets; one end of the rectangular block is provided with a liquid inlet groove, which is fixedly sealed and connected to one end of the rough crack body, and one end of the two reaction liquid inlets penetrates the liquid inlet groove. One end of the rectangular block of the outlet chamber 5 is provided with a liquid outlet groove, which is fixedly sealed and connected to one end of the rough crack body away from the fluid mixing chamber 1, and a fluid outlet channel is provided at the end of the liquid outlet groove. The microfluidic fracture models 18 of the present invention are all made of transparent materials, so the experimental process in the rough fracture body can be observed and recorded in real time by a camera 19, and have the advantages of high acquisition frame rate, low equipment cost, and strong repeatability.

[0036] Another object of the present invention is to design a fracture reactive precipitation experimental device based on the above-mentioned microfluid fracture model 18, such as Figure 2As shown, it includes an injection module, a real-time imaging module, a pressure drop monitoring module, an ion chromatograph 23, a waste liquid collection module and the above-mentioned microfluidic fracture model 18. The functions of each module are clear and easy to assemble and disassemble; the injection module is connected to the fluid mixing chamber 1 through a pipeline with a valve, and can inject reactive fluid into the microfluidic fracture model 18; the real-time imaging module is used for real-time imaging of the fracture reactive precipitation experiment, and the pressure drop monitoring module can monitor the fluid pressure at both ends of the rough fracture body; the real-time imaging module includes a camera 19, which is arranged above the microfluidic fracture model 18, and the camera 19 is electrically connected to a computer 22. Through the image capture of the camera 19 and the data acquisition of the computer 22, the real-time visual observation of the dynamic process of reactive precipitation in the fracture is realized. The pressure drop monitoring module includes a first pressure sensor 16 arranged at the liquid inlet groove of the microfluidic fracture model 18 through a first valve 17 and a second pressure sensor 20 arranged at the liquid outlet groove of the microfluidic fracture model 18 through a second valve 21. The pressure drop monitoring during the precipitation process is realized through real-time monitoring of the two pressure sensors and data collection by a computer 22.

[0037] Specifically, the injection module of this embodiment includes a first injection pump 10 and a second injection pump 11; the first injection pump 10 is provided with a first reaction liquid injector 9, the first reaction liquid injector 9 is connected to a first three-way valve 15 through a pipeline, the first three-way valve 15 is connected to a first reaction liquid inlet 6 of the fluid mixing chamber 1 through a pipeline, and a hydrochloric acid injector 25 is connected to the third valve port of the first three-way valve 15; the second injection pump 11 is provided with a second reaction liquid injector 12, the second reaction liquid injector 12 is connected to a second three-way valve 14 through a pipeline, the second three-way valve 14 is connected to a second reaction liquid inlet 7 of the fluid mixing chamber 1 through a pipeline, and a deionized water injector 13 is connected to the third valve port of the second three-way valve 14. The first injection pump 10 and the second injection pump 11 in the present invention can be replaced with a lifting platform and a Martens flask to study the reactive precipitation generation behavior under constant water head conditions.

[0038] The waste liquid collection module of this embodiment includes a waste liquid collection bottle 24, and the fluid outlet channel of the outlet chamber 5 is connected to the waste liquid collection bottle 24 through a pipeline; the ion chromatograph 23 can measure the cation concentration of the waste liquid in the waste liquid collection bottle 24, and realize the quantitative analysis of the precipitation in the cracks. In combination with the ion chromatograph 23, the waste liquid dissolved by hydrochloric acid in the microfluidic crack model 18 after the precipitation test is collected, and the cation concentration (Ca 2+ ,Mg 2+ etc.) and thus the mass of the sediment (MgCO3, CaCO3) in the cracks can be calculated.

[0039] The present invention also provides a fracture reactive precipitation experimental method, comprising equipment assembly and debugging steps and experimental steps, the equipment assembly and debugging steps comprising:

[0040] To make a transparent microfluidic fracture model 18, glue the first acrylic block 2 and the second acrylic block 3 to the left and right sides of the rough glass block 4, and glue the first acrylic block 2, the second acrylic block 3 and the rough glass block 4 to the slide glass 8 to form a rough fracture body. The rough fracture body of the present invention can also be replaced by a microfluidic fracture chip prepared by laser etching or wet etching technology. Use glue to glue the fluid mixing chamber 1 to the front end of the rough fracture body, and glue the outlet chamber 5 to the rear end of the rough fracture body. Let it stand for 24 hours to allow the glue to completely solidify, and complete the preparation of the microfluidic fracture model 18.

[0041] The pipelines of the fluid injection and waste liquid collection modules are connected, and the first reaction liquid syringe 9 and the second reaction liquid syringe 12 are fixed to the first injection pump 10 and the second injection pump 11 respectively. The first reaction liquid syringe 9 and the hydrochloric acid syringe 25 are connected to the first reaction liquid inlet 6 through the first three-way valve 15, and the second reaction liquid syringe 12 and the deionized water syringe 13 are connected to the second reaction liquid inlet 7 through the second three-way valve 14. The fluid outlet channel of the outlet chamber 5 is connected to the waste liquid collection bottle 24 through a pipeline to complete the pipeline connection.

[0042] Installation and adjustment of the real-time imaging and pressure drop monitoring module: connect the computer 22 and the camera 19, adjust the working distance between the camera 19 and the microfluidic fracture model 18, and complete the imaging quality adjustment after the image is clear. Connect the first pressure sensor 16 and the second pressure sensor 20 to the inlet and outlet of the microfluidic fracture model 18 through the first valve 17 and the second valve 21, respectively, to complete the installation of the pressure drop monitoring module.

[0043] The experimental steps of the present invention are as follows:

[0044] Expel the air in the rough fracture model, switch the second three-way valve 14 to the deionized water injector 13, inject deionized water, and make the deionized water flow into the waste liquid collection bottle 24 through the microfluid fracture model 18. When the deionized water completely fills the microfluid fracture model 18, stop injecting deionized water;

[0045] Induce precipitation reaction, adjust the first three-way valve 15 and the second three-way valve 14, switch to the first reaction liquid injector 9 and the second reaction liquid injector 12 respectively, adjust the first injection pump 10 and the second injection pump 11, so that the two reaction fluids are injected into the cracks of the microfluidic crack model 18 at a constant and same flow rate at the same time, and the two reaction fluids are mixed in the microfluidic crack model 18 to induce calcium carbonate precipitation reaction;

[0046] Real-time visual monitoring, turning on the camera 19 to record the precipitation generation process in real time, and simultaneously recording the data of the two pressure sensors to monitor the pressure drop caused by the precipitation;

[0047] After the experiment is completed, when the total volume of the injected reaction solution reaches a preset value, the injection of the reaction solution is stopped, the first injection pump 10 and the second injection pump 11 are turned off, and the camera 19 is turned off, and the experiment is completed;

[0048] For quantitative analysis of the precipitation, after the experiment is over, the first three-way valve 15 is switched to the hydrochloric acid injector 25, and the hydrochloric acid solution is injected, so that the hydrochloric acid solution passes through the microfluidic fracture model 18 to dissolve the precipitation, and the waste liquid flows into the waste liquid collection bottle 24. After the waste liquid is collected, the cation concentration is measured by the ion chromatograph 23, so as to reversely calculate the mass of the precipitation remaining in the fracture of the microfluidic fracture model 18. In another real-time example, the Ca in the waste liquid after the experiment can also be measured by titration. 2+ and Mg 2+ The concentration of cations.

[0049] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A microfluidic fracture model, characterized in that: include: A glass slide, on which a transparent rough crack body is fixed; A fluid mixing chamber, which is arranged at one end of the rough fracture body and can inject different reaction fluids into the rough fracture body; The outlet cavity is fixedly arranged at the other end of the rough fracture body and can guide the reacted solution in the rough fracture body out.

2. The microfluidic fracture model according to claim 1, characterized in that: A rough glass block is fixed on the glass slide, and symmetrically arranged acrylic blocks are fixedly connected to both sides of the rough glass block; the acrylic block and the rough glass block are fixedly bonded to the glass slide to form the rough crack body.

3. The microfluidic fracture model according to claim 1, characterized in that: The fluid mixing chamber comprises a transparent rectangular block, on which two horizontally inclined reaction liquid inlets are arranged; the ends of the two reaction liquid inlets are both connected to the rough fracture body.

4. The microfluidic fracture model according to claim 3, characterized in that: A liquid inlet groove is provided at one end of the rectangular block, and the liquid inlet groove is fixedly and sealedly connected with one end of the rough crack body, and one end of the two reaction liquid inlets passes through the liquid inlet groove.

5. The microfluidic fracture model according to claim 1, characterized in that: The outlet cavity comprises a transparent rectangular block, one end of which is provided with a liquid outlet groove, the liquid outlet groove is fixedly and sealedly connected with one end of the rough fracture body away from the fluid mixing cavity, and the end of the liquid outlet groove is provided with a fluid outlet channel.

6. A crack reactive precipitation experimental device, characterized in that: It comprises an injection module, a real-time imaging module, a pressure drop monitoring module and a microfluidic fracture model as described in any one of claims 1 to 5; the injection module is connected to the fluid mixing chamber through a pipeline with a valve, and can inject reactive fluid into the microfluidic fracture model; the real-time imaging module is used for real-time imaging of fracture reactive precipitation experiments, and the pressure drop monitoring module can monitor the fluid pressure at both ends of the rough fracture body.

7. The fissure reactive precipitation experimental device according to claim 6, characterized in that: The injection module includes a first injection pump and a second injection pump; the first injection pump is provided with a first reaction liquid injector, the first reaction liquid injector is connected to a first three-way valve through a pipeline, the first three-way valve is connected to one of the reaction liquid inlets of the fluid mixing chamber through a pipeline, and a hydrochloric acid injector is connected to the third valve port of the first three-way valve; the second injection pump is provided with a second reaction liquid injector, the second reaction liquid injector is connected to a second three-way valve through a pipeline, the second three-way valve is connected to the second reaction liquid inlet of the fluid mixing chamber through a pipeline, and a deionized water injector is connected to the third valve port of the second three-way valve.

8. The fissure reactive precipitation experimental device according to claim 6, characterized in that: The real-time imaging module includes a camera, which is arranged above the microfluidic fracture model and is electrically connected to a computer; the pressure drop monitoring module includes pressure sensors respectively arranged at the liquid inlet groove and the liquid outlet groove of the microfluidic fracture model through valves.

9. The fissure reactive precipitation experimental device according to claim 6, characterized in that: It also includes an ion chromatograph and a waste liquid collection module, wherein the waste liquid collection module includes a waste liquid collection bottle, and the fluid outlet channel of the outlet chamber is connected to the waste liquid collection bottle through a pipeline; the ion chromatograph can measure the cation concentration of the waste liquid in the waste liquid collection bottle.

10. A crack reactive precipitation experimental method, characterized in that: The steps include: Step 1: remove the air in the rough fracture model, switch the second three-way valve to the deionized water injector, inject deionized water, and make the deionized water flow into the waste liquid collection bottle through the microfluidic fracture model. When the deionized water completely fills the microfluidic fracture model, stop injecting deionized water; Step 2, inducing a precipitation reaction, adjusting the first three-way valve and the second three-way valve, switching to the first reaction liquid injector and the second reaction liquid injector respectively, adjusting the first injection pump and the second injection pump, so that the two reaction fluids are simultaneously injected into the cracks of the microfluidic crack model at a constant and same flow rate, and the two reaction fluids are mixed in the microfluidic crack model to induce a calcium carbonate precipitation reaction; Step 3: Real-time visual monitoring: Turn on the camera to record the precipitation process in real time, and record the data of two pressure sensors at the same time to monitor the pressure drop caused by precipitation; Step 4, completing the experiment, when the total injected reaction solution volume reaches the preset value, stop injecting the reaction solution, turn off the first injection pump and the second injection pump, turn off the camera, and the experiment is completed; Step 5, quantitative analysis of the precipitate. After the experiment is completed, switch the first three-way valve to the hydrochloric acid syringe, inject the hydrochloric acid solution, and allow the hydrochloric acid solution to pass through the microfluidic fracture model to dissolve the precipitate. The waste liquid flows into the waste liquid collection bottle. After collecting the waste liquid, the cation concentration is measured using an ion chromatograph to inversely calculate the mass of the precipitate remaining in the fracture of the microfluidic fracture model.

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