A storage simulation device and a storage simulation method for characterizing carbon dioxide dissolution and reaction progress

Abstract

The application belongs to the technical field of carbon dioxide geological storage, and discloses a storage simulation device and a storage simulation method for characterizing carbon dioxide dissolution and reaction progress, the storage simulation device comprising a light source, a sealed container, an injection system connected with the sealed container, a temperature controller and a data acquisition and analysis system, the sealed container being internally provided with a transparent porous medium model, the sealed container wall being provided with a light transmission window and a visual window, the light transmission window and the visual window being respectively arranged on two sides of the transparent porous medium model, the transparent porous medium model being filled with a formation water simulation liquid, and the formation water simulation liquid being dissolved with an acid-base indicator, the device being capable of realizing visual observation of carbon dioxide convection dissolution and chemical reaction progress in a saline aquifer, accurately measuring a carbon dioxide dissolution rate, and providing effective theoretical support for carbon dioxide storage site selection and storage efficiency evaluation under complex geological conditions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon dioxide geological storage, and particularly relates to a storage simulation device and a storage simulation method for characterizing carbon dioxide dissolution and reaction progress. BACKGROUND

[0002] Since human beings entered the new industrial era, the application of fossil energy has promoted the rapid development of technology and economy of human society, but at the same time, its byproduct, carbon dioxide, has caused great burden to the environment, leading to a series of problems such as global warming and sea level rise. Carbon dioxide geological storage is a technology that is widely concerned at present, which is to inject carbon dioxide into underground reservoirs at a certain pressure to store it, which can effectively reduce carbon emissions. Deep saline aquifer is a very potential storage site. Deep saline aquifer has high porosity, permeability and relatively complete trap structure, which can prevent carbon dioxide from escaping and also can dissolve a large amount (usually calculated in megatons) of carbon dioxide under the action of high formation pressure, so it is very conducive to the migration and permanent storage of carbon dioxide.

[0003] When carbon dioxide is injected into deep saline aquifer, due to the smaller density, carbon dioxide will form a gas cap at the top of the reservoir, and then slowly dissolve into the underlying brine, forming a saturated CO2 brine with higher density at the top of the saline aquifer. For example, under typical reservoir pressure conditions, 10 MPa, 50℃, the density of the top saturated carbon dioxide brine increases by 9.5 kg / m 3 Under the driving of this density difference, gravity convection will occur in the saline aquifer from top to bottom, promoting the mixing and dissolution of carbon dioxide and improving the storage efficiency.

[0004] At the same time, carbon dioxide dissolved in water is acidic and can react with various components in brine and matrix minerals, such as acid-base neutralization reaction, mineral dissolution reaction, precipitation reaction, etc., which will significantly affect the storage amount, storage rate and storage safety of carbon dioxide. The involvement of chemical reactions makes the dissolution process of carbon dioxide more difficult to predict, and the comprehensive consideration of carbon dioxide convection and dissolution process considering chemical reactions is extremely important for correct evaluation of carbon dioxide storage potential, storage efficiency and storage site selection. Therefore, it is necessary to characterize the dissolution and reaction rules of carbon dioxide when chemical reactions are involved through experimental methods, and to effectively measure the dissolution rate of carbon dioxide.

[0005] Monitoring the sealing process can provide technical guidance and theoretical support for carbon dioxide geological sealing practical work. There are experimental devices for simulating carbon dioxide sealing in the prior art. For example, the patent document with publication number CN117607140A discloses a visual experimental device and method for measuring the dissolution rate of carbon dioxide in liquid phase in porous media. The visual experimental device and method of the patent document can predict the dissolution rate of carbon dioxide in formation water. However, the visual experimental device has a core disadvantage: it cannot characterize the dissolution and chemical reaction rules of carbon dioxide. In the carbon dioxide sealing process, the convection dissolution process and chemical reaction process of carbon dioxide in the formation water of the same saline aquifer are different. At the same time, due to the differences in reservoir porosity and the properties of formation water in different saline aquifers, the convection dissolution process of carbon dioxide in different saline aquifers is different, and the chemical reaction process of carbon dioxide and formation water in different saline aquifers is also different. Therefore, the dissolution and chemical reaction of carbon dioxide is a very complex process, and there is no other technical means in the prior art to characterize this complex process.

[0006] Therefore, in view of the above, there is an urgent need for a simulation device and simulation method that can characterize the convection dissolution and chemical reaction process of carbon dioxide in formation water under high temperature and high pressure conditions and accurately measure the dissolution rate of carbon dioxide. SUMMARY

[0007] To solve the above-mentioned disadvantages of the prior art, the present application discloses a sealing simulation device for characterizing the dissolution and reaction process of carbon dioxide, comprising a light source, a sealed container, an injection system connected with the sealed container, a temperature controller and a data acquisition and analysis system,

[0008] The closed container comprises a kettle body and a cover body detachably connected with the kettle body, the closed container is provided with a gas injection valve and a gas outflow valve, the closed container is provided with a transparent porous medium model, the closed container wall is provided with a light transmission window and a visualization window, the light transmission window and the visualization window are respectively arranged on both sides of the transparent porous medium model, the transparent porous medium model is filled with formation water simulation liquid, the transparent porous medium model simulates the reservoir structure of the saline aquifer, the formation water simulation liquid simulates the formation water in the saline aquifer, the formation water simulation liquid dissolves an acid-base indicator, the pH value of the formation water simulation liquid is outside the color change range of the acid-base indicator, the pH value of the carbon dioxide saturated aqueous solution or the reaction product of carbon dioxide and the formation water simulation liquid is within the color change range of the acid-base indicator, the acid-base indicator is used to characterize the pH change trend of the formation water simulation liquid in the simulation experiment, according to the change trend, the carbon dioxide dissolution process in the formation water simulation liquid can be characterized, or the chemical reaction process in the formation water simulation liquid can also be characterized, and a suitable acid-base indicator with a color change range is selected according to the process to be characterized.

[0009] The injection system comprises a carbon dioxide gas source, a booster pump and an injection pump connected in sequence, the booster pump is used to increase the pressure of the carbon dioxide flowing out of the carbon dioxide gas source to the pressure of the saline aquifer, and the injection pump is connected with the gas injection valve.

[0010] The temperature controller is used to regulate the temperature in the closed container to simulate the temperature conditions of the deep saline aquifer.

[0011] The data acquisition and analysis system comprises a flow meter, a camera, data analysis software and image processing software, the flow meter is arranged between the injection pump and the gas injection valve and is signal connected with the data analysis software, the light source is arranged at the light transmission window outside the closed container, the camera is arranged at the visualization window outside the closed container and is signal connected with the image processing software, and the camera captures the color change of the formation water simulation liquid in the medium model under the irradiation of the light source.

[0012] The medium model of the present application is used for simulating the reservoir environment of a salt water layer, after carbon dioxide is injected into a sealed container through an injection system, the carbon dioxide is dissolved in the formation water simulation liquid and reacts, realizing the simulation of the real injection state, since the acid-base indicator is dissolved in the formation water simulation liquid, with the dissolution and chemical reaction of the carbon dioxide in the formation water simulation liquid, the formation water simulation liquid will present different interface changes at different times, after the interface changes of the formation water simulation liquid at different times are captured by the camera, the camera can transmit the image information to the image processing software, the image processing software performs color enhancement and interface identification on the image, obtaining the interface change image of the formation water simulation liquid, which can intuitively represent the carbon dioxide dissolution and reaction rule in the deep salt water layer, the flow meter is used for capturing the volume of the carbon dioxide flowing into the sealed container, and transmitting the volume information to the data analysis software, after the simulation experiment is completed, the data analysis software is used for calculating the dissolution rate of the carbon dioxide.

[0013] The carbon dioxide dissolution and storage simulation device of the present application can simulate the storage process of carbon dioxide in the deep salt water layer, and can represent the dissolution process or reaction process of carbon dioxide in the salt water layer, and can also accurately measure the dissolution rate of carbon dioxide, which provides technical guidance and theoretical support for the actual work of carbon dioxide geological storage from multiple directions.

[0014] In a preferred scheme, the transparent porous medium model in the sealed container is at least two groups, and the acid-base indicator includes an acidic indicator representing the dissolution process and an acid-base indicator representing the reaction process.

[0015] The acidic indicator representing the dissolution process is dissolved in at least one group of transparent porous medium models, and the acid-base degree of the formation water simulation liquid is outside the color change range of the acidic indicator representing the dissolution process, and the acid-base degree of the carbon dioxide saturated aqueous solution is within the color change range of the acidic indicator representing the dissolution process; the acid-base indicator representing the reaction process is dissolved in at least one group of transparent porous medium models, and the acid-base degree of the formation water simulation liquid is outside the color change range of the acid-base indicator representing the reaction process, and the acid-base degree of the reaction product of the carbon dioxide and the formation water simulation liquid is within the color change range of the acid-base indicator representing the reaction process. The acidic indicator representing the dissolution process and the acid-base indicator representing the reaction process are dissolved in different transparent porous medium models, so as to realize the simultaneous observation of the dissolution process and the chemical reaction process.

[0016] When the formation water simulation liquid is a weak acid solution or a weak alkaline solution, the interface change of the carbon dioxide dissolution process can be presented when the acid indicator representing the dissolution process is dissolved in the formation water simulation liquid; when the formation water simulation liquid is a weak alkaline solution, the acid-base indicator representing the reaction process needs to be selected as an alkaline indicator; when the formation water simulation liquid is a weak acid solution, whether the acid-base indicator representing the reaction process is selected as an acid indicator or an alkaline indicator needs to be selected according to the properties of the formation water. Specifically, the acid indicator or the alkaline indicator with a suitable color change range can be selected according to the pH of the formation water solution, the ion type of the formation water solution and the environmental conditions (temperature and pressure) of the formation water.

[0017] Further, the transparent porous medium model is composed of a transparent glass container and transparent spherical media densely packed in the transparent glass container, the formation water simulation liquid is filled in the pores between the transparent spherical media, and the transparent spherical media in the transparent glass container are of the same size or different sizes.

[0018] The transparent porous medium model with the transparent spherical media of the same size densely packed in the transparent glass container can obtain a transparent porous medium model with uniform permeability to simulate a homogeneous saltwater layer environment; the transparent porous medium model with two or more sizes of transparent spherical media densely packed in the transparent glass container can obtain transparent porous medium models with different porosities to simulate a non-homogeneous saltwater layer environment. Thus, real simulation of various medium environments is realized.

[0019] Preferably, the light transmission window and the visualization window are made of sapphire glass material, which has high light transmission and high temperature and pressure resistance, and can ensure visual observation of the entire dissolution and reaction process under high temperature and high pressure experimental conditions.

[0020] Further, the temperature controller can be a refrigeration and heating compressor, which adopts oil bath temperature control. Since carbon dioxide injection has a high pressure, a large amount of heat is released when the gas is compressed, so it is necessary to monitor and adjust the temperature in the sealed container in real time to make the carbon dioxide dissolution process under isothermal conditions, thereby improving the experimental precision.

[0021] Further, the data acquisition and analysis system further comprises a temperature and pressure sensor, which extends into the sealed container, is connected with the temperature controller, and is used to monitor the temperature change in the sealed container in real time and feed back the temperature signal to the temperature controller to realize real-time regulation and control of the temperature environment in the sealed container by the temperature controller. The temperature and pressure sensor can also monitor the pressure change in the sealed container in real time and regulate the pressure through a pressure booster when the pressure changes.

[0022] Further, an insulation layer is arranged outside the sealed container.

[0023] The application also discloses a storage simulation method for characterizing carbon dioxide dissolution and reaction progress, which utilizes any of the storage simulation devices and adopts the following steps:

[0024] S1, placing a transparent porous medium model filled with formation water simulation liquid into a sealed container, the formation water simulation liquid being dissolved with an acid-base indicator, sealing the sealed container, and placing the transparent porous medium model in the middle of the sealed container to ensure that the overall appearance of the transparent porous medium model can be clearly observed through a visual window;

[0025] S2, controlling the temperature in the sealed container to be the temperature of the saltwater layer to be simulated by a temperature controller;

[0026] S3, opening a gas injection valve and a gas outflow valve, carbon dioxide in the carbon dioxide gas source being injected into the sealed container by a booster pump after being pressurized, and air in the sealed container being blown out of the gas outflow valve by the carbon dioxide, the gas outflow valve being closed after 8-15 seconds, and then the pressure in the container continuously increasing, the pressurized carbon dioxide having a pressure equal to the pressure of the saltwater layer to be simulated;

[0027] S4, capturing an image of the formation water simulation liquid in the medium model by the camera and sending the image to image processing software, the image processing software performing color enhancement and image processing on the image to obtain an interface change image of the formation water simulation liquid, and it is necessary to note that, in order to simulate the physical process of downward dissolution and reaction of the carbon dioxide gas cap with constant pressure, the pressure needs to be increased to the preset pressure in the shortest possible time, otherwise, a large amount of carbon dioxide will be dissolved in the pressure rising process, which will significantly affect the accuracy of the experiment, therefore, the experiment should strictly follow the procedure to pressurize the carbon dioxide to the preset pressure by the booster pump and then inject the carbon dioxide into the container;

[0028] S5, monitoring the volume of the carbon dioxide injected into the sealed container by the flow meter and sending the volume to data analysis software, and the data analysis software calculating the carbon dioxide dissolution rate by formula (I);

[0029]

[0030] In formula (I), F is the carbon dioxide dissolution rate, i.e., the dissolution flux, and the unit is mol / (m 2·s), the physical meaning of which is the amount of dissolved carbon dioxide per unit area per unit time; P is the pressure in the closed container, which is the same as the pressure of the saltwater layer to be simulated; A is the cross-sectional area of the medium model; Z is the compressibility coefficient of carbon dioxide, which is related to temperature and pressure, and is expressed as Z(T, P); R is the gas constant, which is 8.314 J / (mol·K); T is the temperature in the closed container, which is the same as the temperature of the saltwater layer to be simulated; d is a differential symbol; V is the injection volume of carbon dioxide; V l is the injection volume of carbon dioxide in the leakage section; and t is the simulation experiment time.

[0031] It should be noted that the experiment time in the simulation experiment needs to be long enough, at least 1.5 times the time for carbon dioxide to reach saturation, that is, the total experiment time is at least 1.5 times the time for the color to no longer change; this is to ensure that the volume change after the dissolution of carbon dioxide is monitored, and the volume change at this time is caused by the leakage of the container, so that the data can help verify or correct the observation data, and ensure the accuracy of the results.

[0032] Preferably, step S1 specifically comprises: dissolving an acidic indicator for characterizing the dissolution process and an acid-base indicator for characterizing the reaction process in the formation water simulation liquid, respectively, and injecting the formation water simulation liquid dissolved with the acidic indicator for characterizing the dissolution process and the formation water simulation liquid dissolved with the acid-base indicator for characterizing the reaction process into different transparent porous medium models. The carbon dioxide dissolution process and the reaction process can be monitored at the same time, and the dissolution and reaction processes can be tracked and characterized at the same time when there is a chemical reaction.

[0033] Preferably, in order to ensure complete dissolution of the acid-base indicator, ultrasonic dispersion can be performed in an ultrasonic disperser for more than 24 h; further, step S1 further comprises: placing transparent glass balls with the same size into a transparent glass container filled with the acid-base indicator and shaking and jarring uniformly, so that the obtained medium model can simulate a homogeneous saltwater layer environment; or placing transparent glass balls with two or more sizes into a transparent glass container filled with the acid-base indicator and shaking and jarring uniformly, so that the obtained medium model can simulate a non-homogeneous saltwater layer environment. The glass balls are added to the container after the formation water simulation liquid is added, which aims to reduce the possible generation of bubbles, so that the obtained transparent porous medium model is more ideal.

[0034] Preferably, in step S1, the formation water simulation liquid is subjected to degassing treatment before the acid-base indicator is dissolved.

[0035] By adopting the above technical solutions, the present application has the following beneficial effects:

[0036] 1. The device can realize the visualization observation of the carbon dioxide convection dissolution and the chemical reaction process under high temperature and high pressure conditions, and can also measure the carbon dioxide dissolution rate in the process accurately and efficiently.

[0037] 2. The device and method can analyze the flow field, reaction process, material distribution and qualitative distribution of material concentration in the carbon dioxide dissolution and reaction according to the qualitative image results and the plume characteristics and color change of the liquid phase.

[0038] 3. The device can flexibly adjust the physical and chemical parameters in the saline aquifer storage, and can realize the regulation of the carbon dioxide solubility, the density difference between the carbon dioxide saturated solution and the formation water, the porosity of the porous medium, the permeability of the porous medium, the chemical reaction type, the chemical reaction rate and the pH indication range by adjusting the temperature, the pressure, the glass ball size, the type of formation water simulation liquid and the acid-base indicator.

[0039] 4. The device can automatically collect the flow and image and automatically process by using the data acquisition and analysis system, realize the automatic discrimination of the dissolution and reaction interface, avoid the tediousness and error caused by manual operation, ensure the experimental efficiency, improve the consistency of the experimental results and improve the experimental precision. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The carbon dioxide dissolution storage simulation device of the embodiment 1 of the present application;

[0041] Figure 2 The interface change image of the carbon dioxide dissolution process and the reaction process in the formation water simulation liquid obtained by the image processing software in the embodiment 2;

[0042] Figure 3 The carbon dioxide injection volume-time change curve measured in the experimental process in the embodiment 2;

[0043] Figure 4A comparison chart of the carbon dioxide dissolution rate obtained in Example 2 and the numerical simulation result under the same conditions;

[0044] Figure 5 The error of the measured carbon dioxide dissolution amount under different medium sizes and solution conditions in Example 3.

[0045] In the figure: 1-light source, 2-temperature controller, 3-kettle body, 4-cover, 5-gas injection valve, 6-gas outlet valve, 7-transparent porous medium model, 8-light transmission window, 9-visualization window, 10-carbon dioxide gas source, 11-boosting pump, 12-injection pump, 13-flow meter, 14-camera, 15-temperature and pressure sensor. DETAILED DESCRIPTION

[0046] Example 1

[0047] As Figure 1 described, the present embodiment discloses a storage simulation device for characterizing carbon dioxide dissolution and reaction progress, comprising a light source 1, a sealed container and an injection system connected with the sealed container, a temperature controller 2 and a data acquisition and analysis system.

[0048] The sealed container comprises a kettle body 3 and a cover 4 detachably connected with the kettle body 3, an insulating layer is arranged outside the sealed container, a gas injection valve 5 and a gas outlet valve 6 are arranged on the sealed container, at least one set of transparent porous medium model 7 is arranged in the sealed container, a light transmission window 8 and a visualization window 9 are arranged on the wall of the sealed container, the light transmission window 8 and the visualization window 9 are made of sapphire glass, the light transmission window 8 and the visualization window 9 are respectively arranged on both sides of the transparent porous medium model 7, the transparent porous medium model 7 is filled with formation water simulation liquid, and an acid-base indicator is dissolved in the formation water simulation liquid according to simulation requirements.

[0049] The injection system comprises a carbon dioxide gas source 10, a boosting pump 11 and an injection pump 12 connected in sequence, the injection pump 12 is connected with the gas injection valve 5, and is used for injecting carbon dioxide into the sealed container.

[0050] The temperature controller 2 is used for regulating the temperature in the sealed container, so as to simulate the temperature condition of deep saline aquifer.

[0051] The data acquisition system comprises a flow meter 13, a camera 14, data analysis software and image processing software, the flow meter 13 is arranged between the injection pump 12 and the gas injection valve 5, and is in signal connection with the data analysis software, the light source 1 is arranged at the light transmission window 8 outside the closed container, the camera 14 is arranged at the visualization window 9 outside the closed container, the light source 1 is turned on, under the irradiation of the light of the light source 1, the camera 14 captures the color change in the formation water simulation liquid in the transparent porous medium model 7, the camera 14 is in signal connection with the image processing software, and is used for sending the captured color change to the image processing software.

[0052] The transparent porous medium model 7 is composed of a transparent glass container and transparent spherical media densely packed in the transparent glass container, the formation water simulation liquid is filled in the pores between the transparent spherical media, and the transparent spherical media in the transparent glass container are of the same size or different sizes.

[0053] The data acquisition and analysis system further comprises a 15 temperature and pressure sensor, the 15 temperature and pressure sensor extends into the closed container, and the temperature and pressure sensor 15 is connected with the temperature controller 2.

[0054] Embodiment 2

[0055] This embodiment takes a sodium hydroxide (NaOH) aqueous solution as the formation water simulation liquid as an example, the NaOH aqueous solution can react with carbon dioxide through an acid-base neutralization reaction, and the product can be dissolved in water, which can be used as one of typical reactions of carbon dioxide dissolved in formation water. The storage simulation device for characterizing the carbon dioxide dissolution and reaction process in embodiment 1 is used to carry out experiments according to the following steps:

[0056] (1) Prepare the NaOH aqueous solution with a concentration of 0.02 mol / L and a pH of 12.3 for degassing treatment to remove dissolved gas therein;

[0057] (2) Take two portions of the degassed NaOH solution, and add alizarin yellow R acid-base indicator and methyl red acid-base indicator into the NaOH solution respectively, the concentration of the alizarin yellow R acid-base indicator and the methyl red acid-base indicator in the NaOH solution is 0.004 wt%; the solution is sealed and ultrasonically dispersed in an ultrasonic disperser for more than 24 h until all the indicators are dissolved; the pH response range of the alizarin yellow R indicator is 10.2-12.0, and the pH response range of the methyl red indicator is 4.4-6.2. The combination of the two has the advantage that the consumption of alkaline substances (consumption of NaOH) and the dissolution of acidic substances (dissolution of CO2) can be monitored simultaneously in the same group of experiments, and the dissolution and chemical reaction of CO2 can be characterized in more detail;

[0058] (3) Prepare three groups of medium models:

[0059] The two kinds of sodium hydroxide solution with different acid-base indicators obtained in step (2) are respectively put into the same transparent glass container, and the total volume of the liquid phase in the two glass containers is V w to obtain the first group of medium models;

[0060] The two kinds of sodium hydroxide solution with different acid-base indicators obtained in step (2) are respectively put into the same transparent glass container, and the total volume of the liquid phase in the two glass containers is V w A transparent glass ball with a diameter of 2 mm is further put into the container, and is vibrated to form a porous medium, thereby obtaining the second group of medium models;

[0061] The two kinds of sodium hydroxide solution with different acid-base indicators obtained in step (2) are respectively put into the same transparent glass container, and the total volume of the liquid phase in the two glass containers is V w A transparent glass ball with a diameter of 0.3 mm is further put into the container, and is vibrated to form a porous medium, thereby obtaining the third group of medium models. The second group and the third group of medium models simulate the reservoir environment of a salt water layer.

[0062] (4) As shown in Figure 2 , after checking the sealing of the container, the three groups of transparent glass containers are kept in an open state and are put into a sealed container. The left side of each of the three groups of transparent glass containers is a sodium hydroxide solution with dissolved alizarin yellow R indicator, and the right side is a sodium hydroxide solution with dissolved methyl red indicator.

[0063] (5) After the equipment is debugged, the cover is closed, the image acquisition system is turned on, and then the temperature and pressure are increased to 1 MPa and 25℃.

[0064] (6) Figure 2 The convection dissolution patterns of carbon dioxide in the NaOH solution at different times are shown, Figure 2 The three rows of images from left to right are the interface change images of the first group, the second group and the third group of medium models, respectively.

[0065] When t = 0 min, i.e., before the carbon dioxide starts to dissolve, the left and right sides of the three groups of medium models are red and yellow, respectively.

[0066] With the dissolution and chemical reaction of CO2, the pH began to change. When t = 10 min, the model on the left side of the first group of media began to change color under the basic indication interval, indicating that the product of the reaction of carbon dioxide and NaOH accumulated at the bottom, causing the pH at the bottom to decrease and thus the color to change. When t = 15 min, the left model had mostly completely changed color, while in the solution on the right side of the model where the acidic interval indicator was present, only a red plume (pH < 4) was visible from top to bottom, which could be considered to be a saturated carbon dioxide fluid, and the plume continued to slow down and the red color gradually disappeared as it descended, without gradually accumulating and changing color at the bottom as on the left side, indicating that carbon dioxide was gradually consumed by reaction while being transported downward. This observation indicates that carbon dioxide continues to mass transfer downward in this system, and the reaction product accumulates at the bottom and the pH < 10, so the left model gradually changes color from bottom to top (pH decreases); after the reaction is complete, the continued dissolution of carbon dioxide causes the right model to gradually change from yellow to red (pH < 4), which changes color much later than the left side.

[0067] When there is a porous medium in the model, the presence of the pore structure has a significant impact on mass transfer. Figure 2 In the second and third groups of media models, it can be found that at any time node, the left and right models are gradually changing color from top to bottom, indicating that the presence of the porous medium severely inhibits the downward mass transfer of carbon dioxide and the reaction product (in other words, the reaction rate is much greater than the mass transfer rate), so the transport of carbon dioxide and the chemical reaction are both gradually completed from top to bottom, producing the observation results shown in Figure 2 .

[0068] As can be seen from Figure 2 , the color change of the indicator caused by the dissolution and reaction consumption of carbon dioxide in pure solution is completely different, and the reasonable use of the indicator can help identify the product and analyze the material distribution. In addition, in a porous medium, the dissolution and chemical reaction of carbon dioxide are significantly different from those in a pure solution, and in porous media of different porosities, the mass transfer rate of carbon dioxide and the reaction region are also different. Different regions of underground brine layers usually have different porosities and different compositions of formation water solutions, and the dissolution and reaction processes of carbon dioxide in different underground brine layers are usually different and cannot be simulated by pure solutions. Therefore, the parallel experimental system and characterization method established in the present application for the dissolution and chemical reaction process of CO2 plays a huge role in identifying convection characteristics and identifying material distribution, and embodies the advantages of the method.

[0069] (7) Figure 3The carbon dioxide injection volume measured in the experiment of porous medium size d = 0.3mm is shown, wherein the red dotted line represents the injection volume change measured after the complete dissolution of carbon dioxide, i.e. the volume change caused by the leakage of the container; it should be noted that the sealed container needs to be checked for its sealing property before the experiment, but due to the long time scale of the experiment, the sealing operation cannot be completely consistent, and leakage is difficult to avoid, so it is necessary to maintain a long enough time for each experiment to ensure the leakage rate of this experiment.

[0070] According to formula (I) and the temperature T, pressure P, injection volume V, and observed leakage volume V l , the dissolution rate of carbon dioxide can be calculated;

[0071]

[0072] In order to confirm the feasibility and accuracy of the experimental device and experimental method described in the present application, the present embodiment also uses the existing numerical calculation software COMSOL to construct a numerical model consistent with the experimental size and conditions to verify each other; the numerical calculation result of COMSOL and the carbon dioxide dissolution rate curve of the third group of medium models obtained by the experiment with time are shown in Figure 4 ;

[0073] Comparison Figure 4 The experimental results and numerical calculation results under the same conditions can be found to have a very good overall consistency, and the dissolution rate of the stable development stage and the end stage of the time scale can be measured very accurately. However, the measurement results and numerical results in the initial stage are quite different. After analyzing the sources of errors in the experiment, it is considered that the main reason for the deviation of the measurement results is the excessive fluctuation of temperature and pressure caused by the instantaneous influx of high-pressure carbon dioxide in the initial stage, which causes measurement deviation. Considering that the initial stage is short and the dissolution amount is small, it is considered that the fluctuation has little effect on the quantitative analysis of the overall dissolution rate and dissolution amount. By comparing the numerical results and experimental results, the error is only about 3%.

[0074] Through this embodiment, it is found that the numerical results and experimental results have good consistency, which shows that the experimental device and experimental method described in the present application can relatively accurately measure the dissolution rate in the main stage of CO2 dissolution, and can well grasp the characteristics of convective dissolution, and the results have high reliability. In addition, the experimental device described in the present application can flexibly adjust the temperature, pressure, solution type, porous medium permeability, presence or absence of chemical reaction and other key parameters in carbon dioxide dissolution and storage, and the physical simulation of its complexity is far superior to numerical simulation.

[0075] Embodiment 3

[0076] The only difference between this embodiment and Embodiment 2 is that this embodiment uses deionized water, sodium hydroxide solution, and calcium hydroxide solution to simulate three types of formation water, and the size of the transparent glass spheres in the medium model is different (the specific dimensions of the embodiment are shown in the figure). Figure 5 The porous medium particle size d is shown in the figure. Other conditions are the same as in Example 2, and will not be repeated here.

[0077] (1) To confirm the accuracy of the experimental method described in this invention, error analysis can be performed by comparing the theoretical and measured values ​​of CO2 solubility. The theoretical value of CO2 solubility is determined by the solubility and chemical reaction amount at a certain temperature and pressure:

[0078] Δn t =V w C s (T,P)+V w γC Rec Formula (II)

[0079] In equation (Ⅱ), Δn t This is the theoretical value for CO2 solubility; C s (T,P) represents the saturation concentration of CO2, which is related to temperature and pressure; V w V represents the volume of the solution within the system. In this example, V is used in the experiment. w =200ml; C Rec This refers to the concentration of the reactant that reacts with CO2; in this example, it is the concentration of OH in the solution. - Ion concentration; γ is the stoichiometric coefficient.

[0080] (2) The measured value of CO2 dissolution (Δn) can be calculated based on the injection volume and leakage rate:

[0081]

[0082] In formula (Ⅲ), The carbon dioxide leakage rate can be determined by the change in the volume of carbon dioxide injected into the leakage section, i.e. t t This represents the total duration of the experiment.

[0083] (3) Comparing the theoretical and measured values ​​of solubility can help determine the error in the experimental data:

[0084]

[0085] (4) Figure 5The errors of all the convection dissolution quantitative experiments of this embodiment are shown, wherein the errors of all the results are less than 10%, and the errors of most of the results are less than 5%. Considering the system errors caused by factors such as temperature fluctuation, temperature and pressure measurement, and gas leakage in the experimental process, it can be considered that the results obtained by the experiment are relatively accurate.

Claims

1. A storage simulation device for characterizing the dissolution and reaction process of carbon dioxide, characterized in that: It includes a light source, a sealed container, and an injection system, a temperature controller, and a data acquisition and analysis system connected to the sealed container. The sealed container includes a vessel body and a cover detachably connected to the vessel body. The sealed container is equipped with a gas injection valve and a gas outflow valve. A transparent porous medium model is placed inside the sealed container. A light-transmitting window and a visualization window are provided on the wall of the sealed container. The light-transmitting window and the visualization window are respectively located on both sides of the transparent porous medium model. The transparent porous medium model is filled with formation water simulation liquid. An acid-base indicator is dissolved in the formation water simulation liquid. The pH of the formation water simulation liquid is outside the color change range of the acid-base indicator. The pH of the carbon dioxide saturated aqueous solution or the pH of the reaction product of carbon dioxide and formation water simulation liquid is within the color change range of the acid-base indicator. The injection system includes a carbon dioxide gas source, a booster pump, and an injection pump connected in sequence, and the injection pump is connected to a gas injection valve. The temperature controller is used to regulate the temperature inside the sealed container to simulate the temperature conditions of a deep saline aquifer. The data acquisition system includes a flow meter, a camera, data analysis software, and image processing software. The flow meter is located between the injection pump and the gas injection valve and is connected to the data analysis software via signal. The light source is located at the light-transmitting window on the outside of the sealed container, and the camera is located at the visualization window on the outside of the sealed container and is connected to the image processing software via signal.

2. The sealing simulation device according to claim 1, characterized in that: The transparent porous medium model in the sealed container is at least two sets, and the acid-base indicator includes an acidic indicator characterizing the dissolution process and an acid-base indicator characterizing the reaction process. At least one set of transparent porous media models contains dissolved acidic indicators characterizing the dissolution process, and the pH of the carbon dioxide saturated aqueous solution is within the color change range of the acidic indicator characterizing the dissolution process. At least one set of transparent porous media models contains dissolved acid-base indicators characterizing the reaction process, and the pH of the reaction products of the carbon dioxide and the formation water simulation liquid is within the color change range of the acid-base indicator characterizing the reaction process.

3. The sealing simulation device according to claim 2, characterized in that: When the formation water simulation solution is a weakly alkaline solution, the acid-base indicator characterizing the reaction process is an alkaline indicator.

4. The sealing simulation device according to claim 1 or 2, characterized in that: The transparent porous media model consists of a transparent glass container and transparent spherical media densely packed in the transparent glass container. The formation water simulation fluid fills the pores between the transparent spherical media. The transparent spherical media in the transparent glass container may be the same size or different sizes.

5. The sealing simulation device according to claim 1, characterized in that: The data acquisition and analysis system also includes a temperature and pressure sensor that extends into a sealed container and is connected to a temperature controller.

6. The sealing simulation device according to claim 1, characterized in that: The sealed container is provided with an insulation layer on the outside; And / or, the light-transmitting window and the visualization window are made of sapphire glass.

7. A method for simulating the storage of carbon dioxide to characterize the dissolution and reaction process, characterized in that, Using the sealing simulation device according to any one of claims 1 to 6, the following steps are performed: S1. Place the transparent porous medium model filled with formation water simulation liquid into a sealed container, wherein the formation water simulation liquid contains dissolved acid-base indicator. S2. The temperature inside the sealed container is controlled by a temperature controller to be the temperature of the saltwater layer to be simulated. S3. Open the gas injection valve and the gas outlet valve. The carbon dioxide in the carbon dioxide gas source is pressurized by the booster pump and then injected into the sealed container by the injection pump. The pressure of the pressurized carbon dioxide is the pressure of the saltwater layer to be simulated. After the air in the sealed container is discharged through the gas outlet valve, the gas outlet valve is closed. S4. The camera captures an image of the formation water simulation liquid in the medium model and sends it to the image processing software. The image processing software performs color enhancement and interface recognition on the image to obtain an image of the interface changes of the formation water simulation liquid. S5. The volume of carbon dioxide injected into the sealed container is monitored by the flow meter and sent to the data analysis software. The data analysis software calculates the carbon dioxide dissolution rate using formula (I). In equation (Ⅰ), F is the carbon dioxide dissolution rate, with units of mol / (m²). 2 ·s); P is the pressure inside the sealed container; A is the cross-sectional area of ​​the medium model; Z is the compressibility coefficient of carbon dioxide, which is related to temperature and pressure and is expressed as Z(T,P); R is the gas constant, with a value of 8.314 J / (mol·K); T is the temperature inside the sealed container; d is the differential sign; V is the volume of carbon dioxide injected; V l t represents the volume of carbon dioxide injected into the leakage section; t represents the simulation experiment time.

8. The sealing simulation method according to claim 7, characterized in that, Using the sealing simulation device according to claim 2, step S1 specifically comprises: An acidic indicator characterizing the dissolution process and an acid-base indicator characterizing the reaction process were dissolved in a formation water simulation solution. The formation water simulation solutions containing the acidic indicator characterizing the dissolution process and the acid-base indicator characterizing the reaction process were then injected into different transparent porous media models.

9. The sealing simulation method according to claim 7, characterized in that, Using the sealing simulation device according to claim 4, step S1 further includes: Place transparent glass spheres of the same size into a transparent glass container containing dissolved acid-base indicator and shake well to compact; or place transparent glass spheres of two or more sizes into a transparent glass container containing acid-base indicator and shake well to compact.

10. The sealing simulation method according to claim 7, characterized in that, In step S1, the formation water simulation solution is degassed before dissolving the acid-base indicator.

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