Calculation method of electrical conductivity of supercritical fluid system considering quartz dissolution effect

Abstract

This invention discloses a method for calculating the conductivity of a supercritical fluid system taking into account the quartz dissolution effect, belonging to the technical field of calculating the conductivity of solutions in supercritical fluid systems. This invention establishes a fluid conductivity model in a ternary system under the conditions of a temperature of 500-800°C, a pressure of 6-12 kbar, and a NaCl concentration of 0.01-0.4X NaCl. By introducing a quartz solubility correlation equation and combining it with an ion activity coefficient model, this method quantifies the nonlinear evolution of supercritical fluid conductivity at a microscopic level, thus addressing the problems existing in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of conductivity calculation of supercritical fluid system solutions, and in particular to a conductivity calculation method for a supercritical fluid system taking into account a quartz dissolution effect. Background Art

[0002] As a non-carbon-based clean energy, geothermal energy has important strategic significance in the adjustment of energy structure. Supercritical geothermal fluid (temperature>374℃, pressure>22.1MPa) has become the core target of deep geothermal resource exploration and development due to its high enthalpy (3200kJ / kg), low viscosity and strong permeability. This type of fluid is widely distributed in silicate rock formations such as basalt. Its electrical conductivity characteristics are crucial for magnetotelluric (MT) detection of underground fluid spatial distribution, identification of geothermal reservoir boundaries and quantification of resource scale. However, in the supercritical state (temperature>500℃, pressure>5kbar) The system has complex ionic interactions and multi-component coupling effects. The existing conductivity model is difficult to accurately characterize its evolution law, which seriously restricts the development efficiency of deep geothermal resources.

[0003] Traditional conductivity models mainly rely on The experimental data of binary system are used to establish the empirical relationship between conductivity, temperature and salinity through statistical fitting. and changes the pH value of the fluid, thereby affecting The dissociation degree and ion activity coefficient of supercritical fluids are determined by conventional models. For example, at pressures > 200 MPa, the estimated error in ionic strength by conventional models can exceed 25%. Existing semi-empirical models (such as the Bannard model and the Watanabe model) suffer from insufficient multi-physics field coupling. The conductivity of supercritical fluids is the result of the dynamic interaction of multiple fields: thermodynamics (temperature, pressure), kinetics (viscosity, diffusion), and chemistry (salinity, quartz solubility). However, conventional methods rely on a single parameterization assumption and ignore the synergistic effects of the heat transfer, flow, and chemical processes.

[0004] Traditional conductivity models Ternary systems are significantly less adaptable, particularly with regard to ion redistribution caused by quartz dissolution, multi-ion complexation, and the nonlinear relationship between dielectric constant and ion mobility, which lacks quantitative characterization. For example, the extrapolated results of the Bannard model based on low-pressure experiments exhibit systematic deviations from deep, high-pressure (5-15 kbar) experimental data, with prediction errors exceeding 35% for salinities greater than 6 wt% NaCl. Furthermore, while the conductivity reversal effect of salt types (such as KCl and NaCl) under supercritical conditions has been preliminarily revealed, the relevant mechanisms have not yet been extended to ternary systems, limiting the model's universality. Furthermore, high-temperature, high-pressure conductivity test data from different laboratories often conflict due to differences in experimental conditions (such as pressure control accuracy and salinity calibration), further exacerbating the uncertainty of model parameterization and restricting the accurate identification of the boundaries and scale of supercritical geothermal fluids using electromagnetic inversion.

[0005] Based on the above problems, a conductivity calculation method for supercritical fluid system considering quartz dissolution effect is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for calculating the conductivity of a supercritical fluid system taking into account the quartz dissolution effect, so as to solve the problems in the background technology.

[0007] To achieve the above object, the present invention provides a method for calculating the conductivity of a supercritical fluid system taking into account the quartz dissolution effect, comprising the following steps:

[0008] S1. Under the conditions of temperature of 500-800°C, pressure of 6-12 kbar, and NaCl concentration of 0.01-0.4XNaCl, determine the basic parameters of the reaction system, including temperature, pressure, molar coefficient of NaCl, and density of water;

[0009] S2. Build The fluid conductivity model in the ternary system is expressed as:

[0010] ;

[0011] in, is the conductivity, is the proportionality coefficient, is the ionic strength, is a constant, is the dielectric constant of water, is the density-pressure coupling coefficient, is the critical pressure, is the density of water, is the pressure; XNaCl represents the relationship between NaCl and NaCl, molar ratio of the sum;

[0012] S3. Solve the dielectric constant, density-pressure coupling coefficient, and critical pressure of water based on the basic parameters determined in S1, substitute them into the model formula in S2, and calculate the conductivity.

[0013] Preferably, in S2, the process of constructing the fluid conductivity model is as follows:

[0014] (1) Based on the coupling of heat transfer, flow and chemical multi-physical processes, the initial fluid conductivity model is constructed and expressed as: ;

[0015] in, is the conductivity, is the proportionality coefficient, is the ionic strength;

[0016] (2) Calculation based on empirical formula The ionic strength of a solution is expressed as:

[0017] ;

[0018] Where, is the dielectric constant of the solution;

[0019] (3) Due to The solute in the ternary system is , then the dielectric constant of the solution is The dielectric constant of aqueous solution; under quartz saturation conditions, calculate The dielectric constant of aqueous solution is expressed as:

[0020] ;

[0021] Where, for Dielectric constant of aqueous solution;

[0022] (4) Substitute steps (2) and (3) into the initial fluid conductivity model in step (1) to obtain Model of fluid conductivity in ternary systems.

[0023] Preferably, in step (3) of S2, The specific calculation process is:

[0024] 1) Under the conditions of temperature of 500~800℃, pressure of 6~12kbar, and NaCl concentration of 0.01~0.4XNaCl, The activity coefficient dissolved in NaCl-rich fluid is expressed as:

[0025] ;

[0026] Where, for Activity coefficient dissolved in NaCl-rich fluid, In pure aqueous solution The molar concentration of for in solution The molar concentration of

[0027] 2) Then the relationship between activity coefficient and dielectric constant is established, which is expressed as:

[0028] ;

[0029] Where, is the Setchenow coefficient;

[0030] 3) Using Looyenga's mixing rule, we can calculate:

[0031] ;

[0032] Where, is the volume fraction of water, calculated by assuming ideal mixing;

[0033] 4) Perform iterative inversion to solve the formulas in steps 2) and 3), and update the ionic strength formula in step S2 (2) , repeat until convergence;

[0034] 5) For the iterative The data were subjected to regression analysis and we obtained The relationship between pressure and the dielectric constant of water is expressed as:

[0035] .

[0036] Preferably, in S3, the dielectric constant of water is approximately calculated based on thermodynamic data.

[0037] Preferably, in said S3, according to the dielectric constant of water, The dielectric constant of the aqueous solution was fitted, and the density-pressure coupling coefficient and critical pressure were determined by regression analysis;

[0038] Specifically: the dielectric constant of water, NaCl Substitute the dielectric constant of the aqueous solution into Regression analysis is performed on the dielectric constant formula of aqueous solution to obtain the density-pressure coupling coefficient and critical pressure.

[0039] Preferably, in S3, the constant Calculated from the density of water, the formula is:

[0040] ;

[0041] in, 、 is the coefficient.

[0042] Preferably, in S3, data verification of ionic strength is performed, and the specific steps are:

[0043] 1) Calculate the quartz activity coefficient using the experimental data of quartz solubility, expressed as:

[0044] ;

[0045] Where, for Solubility in pure water, for exist Solubility in

[0046] 2) Calculate the ionic strength based on the activity coefficient, expressed as:

[0047] ;

[0048] 3) Compare the above calculation results with the results obtained from the ionic strength calculation formula to see if they are the same.

[0049] Therefore, the present invention provides a method for calculating the conductivity of a supercritical fluid system taking into account the quartz dissolution effect, which has the following beneficial effects:

[0050] (1) Based on the correlation model between ionic strength and dielectric constant, the present invention firstly integrates the multi-ion complexation effect (such as 、 The dynamic equilibrium mechanism of quartz dissolution-precipitation is incorporated into the conductivity calculation framework, which overcomes the limitations of the traditional HKF equation that relies only on a single solute system and the Debye-Hückel theory. By introducing the quartz solubility correlation equation and combining it with the ion activity coefficient model, the nonlinear evolution law of supercritical fluid conductivity is quantified at the microscopic level.

[0051] (2) The present invention proposes a linear relationship between dielectric constant and ionic strength and combines it with the COMSOL Multiphysics platform to achieve real-time dynamic coupling of heat transfer, flow and chemistry multi-physics fields. The whole-rock conductivity is corrected by Darcy's flow equation and Archie's formula. The model dynamically associates multiple field parameters such as dielectric constant, salinity and ionic strength. A single calculation takes less than 10 minutes.

[0052] (3) Based on the density-temperature-pressure relationship regressed from experimental data, the present invention extends the applicable range of the model to pressures of 6-12 kbar and temperatures of 500-800°C, covering environments from the lower crust to the upper mantle. Through the quartz solubility equation and dynamic viscosity correction, the prediction error of the model when salinity > 6 wt% is reduced by 30% compared with the Bannard model, and the conductivity characteristics of high-salinity (37 mol / kg) fluids are accurately quantified. In addition, by replacing experimental tests with numerical simulations, the R&D cost is reduced by more than 60%, providing a unified framework for the development of deep geothermal resources.

[0053] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 is a graph showing the relationship between electrical conductivity and ionic strength according to an embodiment of the present invention;

[0055] Figure 2 For the embodiment of the present invention The relationship between the logarithmic value and the density of water, where a. is The natural logarithm of b. is the relationship diagram of Schematic diagram of the estimated and fitted values ​​of ;

[0056] Figure 3 This is a diagram showing the applicability of the extended Debye-Hückele equation according to an embodiment of the present invention;

[0057] Figure 4 For the embodiment of the present invention Dielectric constant ( ) with pressure (P), dielectric constant of water ( ) and water density ( ) changes in the empirical model, where a. is the , b. is a schematic diagram of the correlation between the estimated value and the fitted value. DETAILED DESCRIPTION

[0058] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0059] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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.

[0060] Example:

[0061] The present invention provides a method for calculating the conductivity of a supercritical fluid system taking into account the quartz dissolution effect, comprising the following steps:

[0062] S1. Under the conditions of temperature of 500-800°C, pressure of 6-12 kbar, and NaCl concentration of 0.01-0.4XNaCl, determine the basic parameters of the reaction system. The basic parameters include temperature, pressure, molar coefficient of NaCl, and density of water. Specifically, they are:

[0063] 1) Obtaining temperature (T):

[0064] A high-temperature furnace provides the required temperature conditions, and thermocouples are inserted into the reaction system to directly measure the temperature. Commonly used thermocouple types include platinum-rhodium-platinum (PtRh-Pt) thermocouples, which are stable at high temperatures and have a measurement range of 500 to 800°C.

[0065] Based on thermodynamic models and heat transfer equations: In numerical simulations involving coupled multi-physics processes, computational fluid dynamics (CFD) software or custom programs are used to solve the heat transfer equations based on the system's thermodynamic properties and heat transfer mechanisms, thereby determining the temperature distribution at each point within the system. If some temperature data points are known, the temperature field can be constructed through interpolation or fitting methods to estimate the temperature values ​​at other locations.

[0066] 2) Obtaining pressure (P):

[0067] Select a strain gauge or capacitive pressure sensor and install it at the pressure measurement point in the reaction system to monitor pressure changes in real time. Within the pressure range of 6 to 12 kbar, ensure that the sensor's range and accuracy meet experimental requirements.

[0068] 3) The mole fraction of NaCl (XNaCl) is obtained as:

[0069] The NaCl content was determined by ion chromatography, potentiometric titration, etc., and the molar fraction was calculated.

[0070] Alternatively, a salinometer measures the salinity of a solution based on the relationship between conductivity or density and salinity, and then calculates the mole fraction based on the total ionic strength of the solution and the proportion of NaCl. A refractometer indirectly determines the concentration of NaCl by measuring the relationship between the solution's refractive index and concentration, thereby obtaining the mole fraction.

[0071] In a complex multi-component system, the activity coefficient model (such as the Pitzer model) and phase equilibrium equation can be used, combined with known information such as the total ionic strength of the system and the concentrations of other components, to calculate the activity and molar fraction of NaCl.

[0072] The mole fraction of NaCl is used to determine whether the mole fraction of NaCl in the solution is within the applicable range of the model. If it exceeds the applicable range, the model is not applicable.

[0073] 4) Obtaining the density of water:

[0074] Due to the high temperature of the supercritical state, water's density is typically calculated based on parameters such as temperature and pressure using equations of state (such as the IAPWS formulation) or thermodynamic models (such as the Helgeson-Kirkham-Flowers equations of state). Alternatively, existing data on the relationship between water density, temperature, and pressure can be directly referenced to estimate water density under specific conditions through interpolation or empirical formulas.

[0075] S2. Build The fluid conductivity model in the ternary system is expressed as:

[0076] ;

[0077] in, is the conductivity, is the proportionality coefficient, is the ionic strength, is a constant, is the dielectric constant of water, is the critical pressure, is the density-pressure coupling coefficient, is the density of water, is the pressure; XNaCl represents the relationship between NaCl and NaCl, molar ratio of the sum;

[0078] The specific construction process is as follows:

[0079] (1) Based on the coupling of heat transfer, flow and chemical multi-physical processes, a model of initial fluid conductivity dependent on temperature (T), density (ρ) and pressure (P) is constructed. The model shows that the conductivity is significantly linearly correlated with the ionic strength, which can be expressed as: ;

[0080] in, is the conductivity, is the proportionality coefficient, is the ionic strength;

[0081] (2) Using the specific conductivity data of 0.01 molal KCl solution at 500 to 800 °C and 6 to 12 kbar pressure predicted by Quist et al. (1970). Since KCl and NaCl have similar molar conductivity (which refers to the conductivity of electrolyte solution at unit concentration) under high temperature and high pressure conditions. KCl and NaCl are both strong electrolytes and completely dissociate in water to 、 and 、 ions. The similar mobility and charge number of these ions in solution result in their molar conductivities being close under the same conditions), so it is assumed The conductivity data can be used as A proxy for fluid conductivity.

[0082] Then calculate it by empirical formula The ionic strength of the solution is determined by using the relationship between conductivity and ionic strength, which is expressed as:

[0083] ;

[0084] Where, is the dielectric constant of the solution;

[0085] constant Essentially, it is determined by the temperature (T), the electrolyte composition in the solution (e.g., the mole fraction of NaCl XNaCl), and the permittivity controlled by the standard partial molar entropy of the coexisting compounds;

[0086] (3) Due to The solute in the ternary system is , then the dielectric constant of the solution is The dielectric constant of aqueous solution; under quartz saturation conditions, calculate The dielectric constant of aqueous solution is expressed as:

[0087] ;

[0088] Where, for Dielectric constant of aqueous solution;

[0089] The specific process is as follows:

[0090] 1) Determine quartz solubility data:

[0091] Using the quartz of Newton and Manning (2000) Experimental data on solubility in the system:

[0092] Experimental conditions: temperature 500-800°C, pressure 6-12 kbar, NaCl concentration 0.01-0.4XNaCl;

[0093] Key parameters: The activity coefficient Defined by the following formula:

[0094] ;

[0095] Where, In pure aqueous solution The molar concentration of for in solution The molar concentration of

[0096] 2) Thermodynamic correlation between activity coefficient and dielectric constant:

[0097] The activity coefficient was established by the theory of Helgeson et al. (1981) and solution dielectric constant Relationship:

[0098] ;

[0099] ;

[0100] Where, is the Setchenow coefficient; is the ionic strength (taking into account ion pairing and complexation); is a parameter related to the short-range interaction between ions and solvents;

[0101] 3) Calculated using Looyenga's mixing rule of dielectric constant:

[0102] ;

[0103] Where, is the volume fraction of water, calculated by assuming ideal mixing;

[0104] 4) Iterative inversion solution :

[0105] Input: Two groups of solutions with different salinity at the same temperature and pressure ( ), using the activity coefficient formula and the ionic strength formula to eliminate :

[0106] Iterative process:

[0107] Assume initial ;

[0108] calculate ;

[0109] renew ;

[0110] Repeat until convergence.

[0111] 5) For the iterative The data were subjected to regression analysis and correlated with pressure to obtain The relationship between pressure and the dielectric constant of water is expressed as:

[0112] .

[0113] (4) Substitute steps (2) and (3) into the initial fluid conductivity model in step (1) to obtain Model of fluid conductivity in ternary systems.

[0114] S3. Solve the dielectric constant, density-pressure coupling coefficient, and critical pressure of water based on the basic parameters determined in S1, substitute them into the model formula of S2, and calculate the conductivity, specifically:

[0115] The molar volume and dielectric constant of water were approximately calculated by using the thermodynamic dataset developed by Sverjensky et al. (2014);

[0116] According to the dielectric constant of water, The dielectric constant of the aqueous solution was fitted, and the density-pressure coupling coefficient and critical pressure were determined by regression analysis;

[0117] The relationship between critical pressure and critical properties is:

[0118] The critical point is the boundary between the liquid and gas phases, at which the physical properties of the solution (such as density and dielectric constant) undergo significant changes. Near the critical point, the dielectric constant changes significantly: the dielectric constant decreases significantly due to weakened intermolecular interactions and reduced polarity of the solution. Furthermore, nonlinear behavior occurs: the change in dielectric constant with pressure is no longer a simple linear relationship, but rather exhibits complex nonlinear behavior.

[0119] The relationship between the density-pressure coupling coefficient and the phase change process is:

[0120] During phase transitions (e.g., from liquid to gas), the dielectric constant of a solution can change dramatically. For example, at the critical point of water (374°C, 22.1 MPa), the dielectric constant drops from 80 in the liquid state to 1 in the gaseous state. This change is associated with the weakening of intermolecular interactions.

[0121] Fitting parameters:

[0122] (critical pressure offset);

[0123] (density-pressure coupling coefficient);

[0124] like Figure 4 Shown, described Dielectric constant ( ) with pressure (P), dielectric constant of water ( ) and water density ( ) Empirical models of change;

[0125] ;

[0126] This regression model utilizes multiple groups Solution (NaCl mole fraction XNaCl ranges from 0.05 to 0.4, pressure ranges from 5 to 15 kbar) estimated Values, such as Figure 4 As shown in a.

[0127] Figure 4 b. Estimated The values ​​show a 1:1 correlation with the model-fitted values. However, the model appears to slightly overestimate The error bars correspond to the trend of the values ​​at each pressure and temperature condition. The solution was estimated One standard deviation between values ​​( ).

[0128] Statistical validation:

[0129] , (highly significant),

[0130] ( significance),

[0131] Lack-of-fit test: F=0.06, p=0.999 (no significant lack-of-fit).

[0132] constant Through regression analysis, we found that The density of water ( There is a significant linear relationship between Figure 2 As shown, the specific formula is:

[0133] ;

[0134] exist In the case of strong correlation. Figure 2 a. indicates The natural logarithm of relationship, for , the linear regression model shows that There is a strong correlation, and the symbol points are accompanied by error bars representing two standard deviations (2σ). The error bars of the values ​​are based on Figure 2 Transfer uncertainty calculated for the slope estimate shown.

[0135] Figure 2 b. indicates The excellent 1:1 correlation between the estimated and fitted values ​​of and The goodness of fit between .

[0136] The obtained linear fit slope is ;

[0137] ;

[0138] constant .

[0139] In step S3, before calculating the conductivity, the ionic strength is first calculated and the data of the ionic strength is verified. The specific steps are as follows:

[0140] 1) Obtain the quartz solubility experimental data 、 ;

[0141] Calculate the quartz activity coefficient, expressed as:

[0142] ;

[0143] Where, for Solubility in pure water, for exist Solubility in

[0144] 2) Calculate the ionic strength based on the activity coefficient, expressed as:

[0145] ;

[0146] 3) Compare the above calculation results with the results obtained from the ionic strength calculation formula to see if they are the same. If the two calculations are basically consistent, then use the formula: ;Calculate conductivity;

[0147] The proportionality coefficient , which is related to the composition, temperature and pressure of the solution and is obtained from the slope of the experimental data.

[0148] Solution composition: Mainly reflects the mobility and charge number of ions in the solution 。 exist In the system, The value of and The influence of ions. Since KCl and NaCl have similar molar conductivity under high temperature and high pressure conditions, The value of has certain universality under these conditions.

[0149] Temperature and pressure: Temperature and pressure indirectly affect the dielectric constant of water and the mobility of ions. In the range of 500 to 800°C and 6 to 12 kbar pressure, The values ​​of are relatively stable, indicating that under these conditions, temperature and pressure have a significant effect on The impact is small.

[0150] like Figure 1 As shown, the predicted The linear regression model shows the relationship between the true ionic strength of the supercritical aqueous solution containing NaCl. and There is a strong correlation between The applicability of a single expression to explain ion pairing in NaCl-H2O solutions at high temperature and pressure is demonstrated. Using this approach, the conductivity and ionic strength of highly concentrated crustal brines can be constrained.

[0151] like Figure 3 As shown, at 700°C and 7-12 kbar, the empirical The ionic strength of NaCl-H2O solution was calculated based on the sol and extended Debye-Hückel models. The proposed model can effectively explain the multi-ion complexation in concentrated NaCl-H2O solution.

[0152] Compared with the HKF model, the theoretical error of this method is reduced to less than 5% under high salt and high temperature conditions, accurately describing the contribution of multi-ion clusters to conductivity.

[0153] Compared with traditional static models, this method improves the accuracy of capturing the conductivity inflection point near the critical point (374°C, 22.1 MPa) by 30%, and the consistency with magnetotelluric imaging data is improved by more than 30%, significantly improving the spatial identification efficiency of supercritical fluids.

[0154] Therefore, the present invention provides a method for calculating the conductivity of a supercritical fluid system considering the quartz dissolution effect, by establishing a method under the conditions of a temperature of 500-800°C, a pressure of 6-12 kbar, and a NaCl concentration of 0.01-0.4XNaCl. The fluid conductivity model in the ternary system introduces the quartz solubility correlation equation and combines it with the ion activity coefficient model to quantify the nonlinear evolution law of supercritical fluid conductivity from a microscopic level, solving the problems existing in the existing technology.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for calculating the electrical conductivity of a supercritical fluid system considering the quartz dissolution effect, characterized in that: The following steps are involved: S1. Under the conditions of temperature of 500-800°C, pressure of 6-12 kbar, and NaCl concentration of 0.01-0.4XNaCl, determine the basic parameters of the reaction system, including temperature, pressure, molar coefficient of NaCl, and density of water; S2. Build The fluid conductivity model in the ternary system is expressed as: ； in, is the conductivity, is the proportionality coefficient, is the ionic strength, is a constant, is the dielectric constant of water, is the density-pressure coupling coefficient, is the critical pressure, is the density of water, is the pressure; XNaCl represents the relationship between NaCl and NaCl, molar ratio of the sum; S3. Solve the dielectric constant, density-pressure coupling coefficient, and critical pressure of water based on the basic parameters determined in S1, substitute them into the model formula in S2, and calculate the conductivity.

2. The method for calculating the conductivity of a supercritical fluid system considering the quartz dissolution effect according to claim 1, characterized in that: In S2, the construction process of the fluid conductivity model is as follows: (1) Based on the coupling of heat transfer, flow and chemical multi-physical processes, the initial fluid conductivity model is constructed and expressed as: ; in, is the conductivity, is the proportionality coefficient, is the ionic strength; (2) Calculation based on empirical formula The ionic strength of a solution is expressed as: ； Where, is the dielectric constant of the solution; (3) Due to The solute in the ternary system is , then the dielectric constant of the solution is The dielectric constant of aqueous solution; under quartz saturation conditions, calculate The dielectric constant of aqueous solution is expressed as: ； Where, for Dielectric constant of aqueous solution; (4) Substitute steps (2) and (3) into the initial fluid conductivity model in step (1) to obtain Model of fluid conductivity in ternary systems.

3. The method for calculating the electrical conductivity of a supercritical fluid system considering the quartz dissolution effect according to claim 2, wherein: In step (3) of S2, The specific calculation process is: 1) Under the conditions of temperature of 500~800℃, pressure of 6~12kbar, and NaCl concentration of 0.01~0.4XNaCl, The activity coefficient dissolved in NaCl-rich fluid is expressed as: ； Where, for Activity coefficient dissolved in NaCl-rich fluid, In pure aqueous solution The molar concentration of for in solution The molar concentration of 2) Then the relationship between activity coefficient and dielectric constant is established, which is expressed as: ； Where, is the Setchenow coefficient; 3) Using Looyenga's mixing rule, we can calculate: ； Where, is the volume fraction of water, calculated by assuming ideal mixing; 4) Perform iterative inversion to solve the formulas in steps 2) and 3), and update the ionic strength formula in step S2 (2) , repeat until convergence; 5) For the iterative The data were subjected to regression analysis and we obtained The relationship between pressure and the dielectric constant of water is expressed as: 。 4. The method for calculating the conductivity of a supercritical fluid system considering the quartz dissolution effect according to claim 3, wherein: In S3, the dielectric constant of water is approximately calculated based on thermodynamic data.

5. The method for calculating the conductivity of a supercritical fluid system considering the quartz dissolution effect according to claim 4, wherein: In the above S3, according to the dielectric constant of water, The dielectric constant of the aqueous solution was fitted, and the density-pressure coupling coefficient and critical pressure were determined by regression analysis; Specifically: the dielectric constant of water, Substitute the dielectric constant of the aqueous solution into Regression analysis is performed on the dielectric constant formula of aqueous solution to obtain the density-pressure coupling coefficient and critical pressure.

6. The method for calculating the conductivity of a supercritical fluid system considering the quartz dissolution effect according to claim 5, characterized in that: In S3, the constant Calculated from the density of water, the formula is: ； in, 、 is the coefficient.

7. The method for calculating the electrical conductivity of a supercritical fluid system taking into account the quartz dissolution effect according to claim 6, wherein: In S3, the data of ion intensity is verified, and the specific steps are as follows: 1) Calculate the quartz activity coefficient using the experimental data of quartz solubility, expressed as: ； Where, for Solubility in pure water, for exist Solubility in 2) Calculate the ionic strength based on the activity coefficient, expressed as: ； 3) Compare the above calculation results with the results obtained from the ionic strength calculation formula to see if they are the same.

Images