Device for measuring CO2 solubility of saline water layer and multi-factor analysis characterization method

Abstract

The invention discloses a saline water layer CO2 solubility measuring device and a multi-factor analysis characterization method.The saline water layer CO2 solubility measuring device comprises a CO2 gas cylinder, a first valve, a metering pump, a second valve, a high-temperature and high-pressure reaction kettle, a third valve, a fluid metering pipe and a gas drainage device which are sequentially connected, and an automatic stirring device is arranged in the high-temperature and high-pressure reaction kettle; the metering pump, the second valve and the high-temperature and high-pressure reaction kettle are arranged in the constant-temperature box. By means of the device, the corresponding amount of gas removed from formation water containing supersaturated CO2 is tested, the solubility of CO2 in formation water under the conditions of different temperatures, pressures, water body mineralization degrees and the like is calculated, temperature, pressure and mineralization degree data obtained on the basis of a single-factor transformation method are fitted with CO2 solubility data, and finally a CO2 solubility characterization formula under the influence of multiple factors is obtained. According to the method, experimental measurement of the CO2 solubility and analysis and characterization of the CO2 solubility influenced by multiple factors are combined, and the solubility of CO2 in the salt water layer can be reliably predicted for the salt water layer under specific conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of CO2 geological storage, and in particular relates to a device for measuring the CO2 solubility in a saline layer and a multi-factor analysis and characterization method. Background Art

[0002] The solubility of CO2 in saline water is one of the main parameters for CO2 storage in saline aquifers and is of great significance in estimating the amount of CO2 stored.

[0003] At present, the existing methods for measuring CO2 solubility in the industry lack an evaluation method for the combined effects of multiple control factors on CO2 solubility. When targeting a specific saline aquifer, complex issues are often over-idealized, leading to misjudgment of the CO2 dissolution and storage capacity of the saline aquifer.

[0004] Since the solubility of CO2 in salt water is controlled by many factors, at this stage, under formation conditions, the main known factors are temperature, pressure, and saline mineralization. Therefore, a series of CO2 solubility experiments need to be carried out for different saline layers in order to accurately obtain the solubility of CO2 under the conditions of the saline layer. Moreover, under the conditions of multi-factor changes, it is also necessary to analyze the changes in CO2 solubility, which will directly affect the evaluation results of the site's CO2 storage capacity. Therefore, at this stage, there is a lack of a measurement device for the solubility of CO2 in saline layers and a multi-factor analysis and characterization method, which has great application prospects in the field of CO2 geological storage technology. Summary of the invention

[0005] The problem to be solved by the present invention is to provide a measuring device for the solubility of CO2 in saline water layers and a multi-factor analysis characterization method. The solubility of CO2 in saline water layers under different conditions is obtained through experiments, and based on the results of the influence of multiple factors, an empirical formula for the solubility of CO2 in saline water layers is fitted.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a device for measuring the CO2 solubility in a saline water layer, comprising a CO2 gas cylinder, the CO2 gas cylinder is connected to a metering pump through a first valve, the metering pump is connected to a high-temperature and high-pressure reactor through a second valve, an automatic stirring device is provided in the high-temperature and high-pressure reactor, the outlet of the high-temperature and high-pressure reactor is connected to a fluid metering pipe through a third valve, the fluid metering pipe is connected to a gas discharge device, and the metering pump, the second valve and the high-temperature and high-pressure reactor are placed in a constant temperature box.

[0007] Further, the CO2 solubility is calculated by using the measuring device through the following steps:

[0008] First, the first valve is opened to fill the metering pump with CO2, and then the first valve is closed, the metering pump is set to the pressure and temperature to be tested, and the water sample to be tested is added to the high temperature and high pressure reactor;

[0009] Secondly, the second valve is opened, CO2 from the metering pump is injected into the high temperature and high pressure reactor, and then the second valve is closed, the pressure is maintained at the pressure to be measured, the reactor is heated to the temperature to be measured, and the automatic stirring device of the high temperature and high pressure reactor is started to allow CO2 to quickly dissolve in the water sample and quickly reach equilibrium;

[0010] Next, the formation water end of the high temperature and high pressure reactor saturated with CO2 that has reached equilibrium is placed downward, and after standing for 10 minutes, the third valve is opened, and the volume of water discharged is measured using the fluid metering tube. 水 , use the gas discharge device to measure the gas volume V CO2 ;

[0011] Finally, the CO2 solubility is calculated as follows:

[0012] S=V CO2 / (V 水 ×ρ 水 )

[0013] Where: 水 is the density of water under the experimental temperature and pressure conditions, and S is the solubility of CO2.

[0014] Furthermore, the volume of the water sample to be tested added to the high temperature and high pressure reactor is 2 / 3 at the beginning.

[0015] Furthermore, the stirring time of the automatic stirring device is not less than 1 hour.

[0016] Furthermore, in order to ensure the accuracy of the experimental test of the amount of dissolved CO2 in water, the experiment was repeated several times and the average value was taken.

[0017] Furthermore, the present invention also provides a multi-factor analysis and characterization method for the solubility of CO2 in a saline layer, using the above-mentioned measuring device for the solubility of CO2 in a saline layer, comprising the following steps:

[0018] S1: Record the CO2 solubility measured by the measuring device and its corresponding environmental conditions, and conduct experiments using a single factor transformation method;

[0019] S2: According to the experimental data, the CO2 solubility and pressure are fitted to obtain the curve fitting formula of CO2 solubility and pressure at different pressures and salinities;

[0020] S3: extract the constant part of the curve fitting formula obtained in S2, and then fit it with the temperature to obtain the fitting formula of solubility-temperature-pressure at different salinities;

[0021] S4: Extract the constant part of the fitting formula obtained in S3, and then fit it with the salinity to obtain the fitting formula of solubility-temperature-pressure-salinity. The predicted results of the fitting formula are compared with the experimental results to ensure the reliability of the fitting results, thereby obtaining the CO2 solubility characterization formula under the influence of multiple factors.

[0022] Furthermore, in S1, the environmental conditions include temperature T, pressure P and water salinity TDS.

[0023] Furthermore, in S2, the curve fitting formula selects one or more of a linear function, an exponential function, and a logarithmic function based on the data.

[0024] Furthermore, in the S2, the curve fitting formula of the CO2 solubility and pressure at different pressures and salinities is:

[0025] S=A×P+B

[0026] Where S is the solubility of CO2, A and B are the constant parts of the linear fitting function, and P is the pressure.

[0027] Further, in S3, the fitting formula of the solubility-temperature-pressure at different salinities is:

[0028] S=C×ln(t)×pD×pE×ln(t)+F,

[0029] Among them, S is the solubility of CO2, C, D, E, F are the constant parts of the fitting, t is the temperature, and p is the pressure.

[0030] The advantages and positive effects of the present invention are:

[0031] The present invention conducts a series of CO2 solubility experiments on saline water layers under specific conditions to obtain the solubility of CO2 under the saline water layer conditions. Based on the results of multiple factors, an empirical formula for the solubility of CO2 in saline water layers is fitted to make reliable predictions, and the predicted results are compared with the actual results to ensure the rationality of the predicted results. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the measuring device according to an embodiment of the present invention.

[0033] Figure 2 It is a schematic diagram of the overall process of an embodiment of the present invention.

[0034] Figure 3 This is a fitting diagram of pressure and CO2 solubility under the condition of a salinity of 7346 mg / L in one embodiment of the present invention.

[0035] Figure 4 This is a fitting diagram of pressure and CO2 solubility under the condition of a salinity of 14692 mg / L in one embodiment of the present invention.

[0036] Figure 5 This is a fitting diagram of pressure and CO2 solubility under the condition of a salinity of 29384 mg / L in one embodiment of the present invention.

[0037] Figure 6 This is a comparison chart of the predicted values ​​and experimental values ​​of the fitting results of the multi-factor characterization of CO2 solubility in one embodiment of the present invention.

[0038] In the figure:

[0039] 1. CO2 gas cylinder; 2. First valve; 3. Metering pump;

[0040] 4. Second valve; 5. High temperature and high pressure reactor; 6. Third valve;

[0041] 7. Fluid metering tube; 8. Gas drainage device; 9. Constant temperature box. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0043] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] The embodiments of the present invention are further described below in conjunction with the accompanying drawings:

[0046] like Figure 1 As shown, a device for measuring the CO2 solubility in a saline water layer comprises a CO2 gas cylinder 1, the CO2 gas cylinder 1 is connected to a metering pump 3 through a first valve 2, the metering pump 3 is connected to a high-temperature and high-pressure reactor 5 through a second valve 4, an automatic stirring device is arranged in the high-temperature and high-pressure reactor 5, an outlet of the high-temperature and high-pressure reactor 5 is connected to a fluid metering pipe 7 through a third valve 6, the fluid metering pipe 7 is connected to a gas discharge device 8, and the metering pump 3, the second valve 4 and the high-temperature and high-pressure reactor 5 are placed in a constant temperature box 9.

[0047] Specifically, the CO2 solubility is calculated by using the measuring device provided in this embodiment through the following steps.

[0048] First, open the first valve 2 to fill the metering pump 3 with CO2, then close the first valve 2, set the metering pump 3 to the pressure and temperature to be tested, and add 2 / 3 of the volume of the water sample to be tested into the high-temperature and high-pressure reactor 5.

[0049] Secondly, open the second valve 4, inject the CO2 from the metering pump 3 into the high temperature and high pressure reactor 5, then close the second valve 4, maintain the pressure at the pressure to be tested, heat to the temperature to be tested, start the automatic stirring device of the high temperature and high pressure reactor 5, so that the CO2 quickly dissolves in the water sample and quickly reaches equilibrium. Specifically, the stirring time is not less than 1 hour.

[0050] Next, place the formation water end of the high-temperature and high-pressure reactor 5 saturated with CO2 downward after reaching equilibrium, and after standing for 10 minutes, open the third valve 6 and use the fluid metering tube 7 to measure the volume of water discharged V 水 , using the gas discharge device 8 to measure the gas volume V CO2 ,In order to ensure the accuracy of the amount of dissolved CO2 in water tested, the ,experiment was repeated three times to ensure the consistency of the ,experimental results.

[0051] Finally, the CO2 solubility is calculated as follows:

[0052] S=V CO2 / (V 水 ×ρ 水 )

[0053] Where: 水 is the density of water under the experimental temperature and pressure conditions, and S is the solubility of CO2.

[0054] like Figure 2 As shown, the present invention also provides a multi-factor analysis and characterization method of CO2 solubility in a saline layer, using the above-mentioned measuring device for CO2 solubility in a saline layer, comprising the following steps:

[0055] S1: Record the CO2 solubility measured by the measuring device and its corresponding environmental conditions. Specifically, the environmental conditions include temperature T, pressure P and water salinity TDS. The single factor transformation method is used to conduct experiments. The specific operation is as follows: assuming that 3 groups of experiments with different temperatures, 4 groups of experiments with different pressures, and 5 groups of experiments with different water salinity are conducted, 3×4×5=60 groups of experiments are required.

[0056] S2: According to the experimental data, the CO2 solubility and pressure are fitted. Based on the data, a linear function, exponential function, logarithmic function, etc. can be selected to obtain the curve fitting formula of CO2 solubility and pressure at different pressures and salinities. Specifically, assuming that the curve fitting formula of CO2 solubility and pressure at different pressures and salinities is,

[0057] S=A×P+B

[0058] Where S is the solubility of CO2, A and B are the constant parts of the linear fitting function, and P is the pressure.

[0059] S3: Extract the constant part of the curve fitting formula obtained in S2, that is, the constant parts A and B of the linear fitting function of S2, and then fit them with the temperature to obtain the fitting formula of solubility-temperature-pressure under different salinities. Assume that the fitting formula is:

[0060] S=C×ln(t)×pD×pE×ln(t)+F,

[0061] Among them, S is the solubility of CO2, C, D, E, F are the constant parts of the fitting, t is the temperature, and p is the pressure.

[0062] S4: Extract the constant part of the fitting formula obtained in S3, that is, the constant part C, D, E, F of the logarithmic function fitting function of S3, and then fit it with the salinity to obtain the fitting formula of solubility-temperature-pressure-salinity. Compare the predicted results of the fitting formula with the experimental results to form a result comparison chart to ensure the reliability of the fitting results, thereby obtaining the CO2 solubility characterization formula under the influence of multiple factors.

[0063] The present invention is described below in conjunction with specific embodiments:

[0064] Install and connect the experimental equipment of the measuring device. All equipment has been cleaned and dried before the experiment.

[0065] First, open the first valve 2, fill the metering pump 3 with CO2, then close the first valve 2, set the metering pump 3 to the pressure and temperature to be tested, and add 2 / 3 volume of the water sample to be tested into the high temperature and high pressure reactor 5. Specifically, the temperatures set in this embodiment are 40°C, 60°C, 90°C, and 120°C, respectively, and the pressures are 10MPa, 15MPa, 20MPa, and 25MPa, respectively, and the mineralization of the water samples used is 7346mg / L, 14692mg / L, and 29384mg / L, respectively.

[0066] Secondly, open the second valve 4, inject the CO2 from the metering pump 3 into the high-temperature and high-pressure reactor 5, then close the second valve 4, maintain the pressure at the pressure to be tested, heat to the temperature to be tested, start the automatic stirring device of the high-temperature and high-pressure reactor 5, and stir for no less than 1 hour to allow the CO2 to quickly dissolve in the water sample and quickly reach equilibrium.

[0067] Next, place the formation water end of the high-temperature and high-pressure reactor 5 saturated with CO2 downward after reaching equilibrium, and after standing for 10 minutes, open the third valve 6 and use the fluid metering tube 7 to measure the volume of water discharged V 水 , using the gas discharge device 8 to measure the gas volume V CO2 , repeated three times and the average value was taken.

[0068] Finally, calculate the CO2 solubility, S = V CO2 / (V 水 ×ρ 水 ) where ρ 水 is the density of water under the experimental temperature and pressure conditions, and S is the solubility of CO2.

[0069] Using the above-mentioned saltwater layer CO2 solubility measurement device, a multi-factor analysis and characterization method of saltwater layer CO2 solubility is performed, comprising the following steps:

[0070] S1: Record the CO2 solubility measured by the measuring device and its corresponding temperature T, pressure P and water salinity TDS and other conditions.

[0071] S2: Fit the CO2 solubility and pressure to obtain the curve fitting formula of CO2 solubility and pressure at different pressures and salinities. Figure 3-5 As shown, the fitting formula results under different conditions.

[0072] S3: extract the constant part of the curve fitting formula obtained in S2, and then fit it with the four temperatures set above to obtain the fitting formula of solubility-temperature-pressure at different salinities.

[0073] S4: Extract the constant part of the fitting formula obtained in S3, and then fit it with the salinity to obtain the fitting formula of solubility-temperature-pressure-salinity:

[0074] S=(-0.00002TDS+0.4088)ln(t)p+(0.00006TDS-1.1604)p+(0.0001TDS-12.203)ln(t)-11.61ln(TDS)+167.92

[0075] Where S is the solubility of CO2; TDS is the mineralization of the water sample; t is the temperature; and p is the pressure.

[0076] Compare the predicted results with the actual results Figure 6 , to ensure the rationality of the prediction results.

[0077] The advantages and positive effects of the present invention are:

[0078] The present invention conducts a series of CO2 solubility experiments on saline water layers under specific conditions to obtain the solubility of CO2 under the saline water layer conditions. Based on the results of multiple factors, an empirical formula for the solubility of CO2 in saline water layers is fitted to make reliable predictions, and the predicted results are compared with the actual results to ensure the rationality of the predicted results.

[0079] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A device for measuring CO2 solubility in saline water layer, characterized by: It includes a CO2 gas cylinder, which is connected to a metering pump through a first valve, and the metering pump is connected to a high-temperature and high-pressure reactor through a second valve. The high-temperature and high-pressure reactor is provided with an automatic stirring device, and the outlet of the high-temperature and high-pressure reactor is connected to a fluid metering pipe through a third valve, and the fluid metering pipe is connected to a gas discharge device. The metering pump, the second valve and the high-temperature and high-pressure reactor are placed in a constant temperature box.

2. The device for measuring CO2 solubility in a saline layer according to claim 1, characterized in that: Using the measuring device, the CO2 solubility is calculated by the following steps: First, the first valve is opened to fill the metering pump with CO2, and then the first valve is closed, the metering pump is set to the pressure and temperature to be tested, and the water sample to be tested is added to the high temperature and high pressure reactor; Secondly, the second valve is opened, CO2 from the metering pump is injected into the high temperature and high pressure reactor, and then the second valve is closed, the pressure is maintained at the pressure to be measured, the reactor is heated to the temperature to be measured, and the automatic stirring device of the high temperature and high pressure reactor is started to allow CO2 to quickly dissolve in the water sample and quickly reach equilibrium; Next, the formation water end of the high temperature and high pressure reactor saturated with CO2 that has reached equilibrium is placed downward, and after standing for 10 minutes, the third valve is opened, and the volume of water discharged is measured using the fluid metering tube. 水 , use the gas discharge device to measure the gas volume V CO2 ; Finally, the CO2 solubility is calculated as follows: S=V CO2 / (V 水 ×ρ 水 ) Where: 水 is the density of water under the experimental temperature and pressure conditions, and S is the solubility of CO2.

3. The device for measuring CO2 solubility in a saline layer according to claim 2, characterized in that: At the beginning, 2 / 3 volume of the water sample to be tested is added into the high temperature and high pressure reactor.

4. A device for measuring CO2 solubility in a saline layer according to claim 2 or 3, characterized in that: The stirring time of the automatic stirring device is not less than 1 hour.

5. A device for measuring CO2 solubility in a saline layer according to claim 2 or 3, characterized in that: In order to ensure the accuracy of the experimental test of the amount of dissolved CO2 in water, the experiment was repeated several times and the average value was taken.

6. A multi-factor analysis and characterization method for CO2 solubility in saline water layers, using the CO2 solubility measurement device of any one of claims 1 to 5, characterized in that: The following steps are included: S1: Record the CO2 solubility measured by the measuring device and its corresponding environmental conditions, and conduct experiments using a single factor transformation method; S2: According to the experimental data, the CO2 solubility and pressure are fitted to obtain the curve fitting formula of CO2 solubility and pressure at different pressures and salinities; S3: extract the constant part of the curve fitting formula obtained in S2, and then fit it with the temperature to obtain the fitting formula of solubility-temperature-pressure at different salinities; S4: Extract the constant part of the fitting formula obtained in S3, and then fit it with the salinity to obtain the fitting formula of solubility-temperature-pressure-salinity. The predicted results of the fitting formula are compared with the experimental results to ensure the reliability of the fitting results, thereby obtaining the CO2 solubility characterization formula under the influence of multiple factors.

7. The multi-factor analysis and characterization method for CO2 solubility in saline water layer according to claim 6 is characterized by: In S1 , the environmental conditions include temperature T, pressure P and water salinity TDS.

8. The multi-factor analysis and characterization method of CO2 solubility in saline water layer according to claim 6 or 7, characterized in that: In S2, the curve fitting formula selects one or more of a linear function, an exponential function, and a logarithmic function based on the data.

9. The multi-factor analysis and characterization method for CO2 solubility in saline water layer according to claim 8, characterized in that: In the S2, the curve fitting formula of the CO2 solubility and pressure at different pressures and salinities is: S=A×P+B Where S is the solubility of CO2, A and B are the constant parts of the linear fitting function, and P is the pressure.

10. The multi-factor analysis and characterization method for CO2 solubility in saline water layer according to claim 9, characterized in that: In S3, the fitting formula of solubility-temperature-pressure at different salinities is: S=C×ln(t)×pD×pE×ln(t)+F, Among them, S is the solubility of CO2, C, D, E, F are the constant parts of the fitting, t is the temperature, and p is the pressure.

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