Method and device for determining depth of gas-liquid transition area of salt-cavern nitrogen dissolution-resistant cavity

Abstract

The invention discloses a method and a device for determining the depth of a gas-liquid transition area of a salt cavern nitrogen dissolution-resistant cavity. The method comprises the following steps: collecting injection data of a salt cavern cavity; the collected data is preprocessed; calculating according to the collected data; comparing the difference between the model prediction result and the actual depth of the gas-liquid transition area, and adjusting and optimizing; and using the trained calculation model to predict and apply the depth of the gas-liquid transition region of the salt cavern nitrogen dissolution-resistant cavity in the future. According to the method and the device for determining the depth of the gas-liquid transition area of the salt-cavern nitrogen dissolution-resistant cavity, a related theoretical calculation formula, a block division method and an iterative calculation method are combined, and a Python programming tool is used for calculation, so that the depth of the gas-liquid transition area of the salt-cavern nitrogen dissolution-resistant cavity can be automatically calculated; the efficiency of solving the complex engineering problem is greatly improved, the temperatures, the nitrogen flow rates, the pressures and the nitrogen densities of different well depths are calculated in a grid division mode, and the calculation result is made to be more close to the actual result.

Description

Technical Field

[0001] The present invention relates to the field of nitrogen dissolution cavity forming gas-liquid transition zone depth calculation, and in particular to a method and device for determining the gas-liquid transition zone depth of nitrogen dissolution cavity forming in salt caverns. Background Art

[0002] The depth of the gas-liquid transition zone in the nitrogen dissolution cavern has an important influence on the depth of the brine drainage pipe in the nitrogen dissolution. According to the on-site feedback of the existing situation, in the nitrogen dissolution cavity making process, there is still gas discharge from the brine drainage pipe about ten meters below the gas-liquid interface, and the depth of the brine drainage pipe has a great influence on the project. If the depth is too high, it will cause a waste of nitrogen resources and an increase in nitrogen costs; if the depth is too low, it will cause a waste of brine drainage pipeline resources and require more resources to complete the brine drainage process.

[0003] Therefore, a more accurate and economical solution for placing brine exhaust pipes is needed. Summary of the invention

[0004] In view of the problems existing in the above-mentioned existing method for determining the depth of the gas-liquid transition zone in the nitrogen-resistance dissolution cavity formation in salt caverns, the present invention is proposed.

[0005] Therefore, the purpose of the present invention is to provide a method for determining the depth of the gas-liquid transition zone of the nitrogen dissolution cavitation in salt caverns, and its purpose is to use a block division method and an iterative calculation method to calculate the depth of the gas-liquid transition zone of the nitrogen dissolution cavitation in salt caverns.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0007] Collect injection data from salt cavern cavities;

[0008] Preprocess the collected data;

[0009] Make calculations based on the data collected;

[0010] By comparing the model prediction results with the actual gas-liquid transition zone depth and optimizing;

[0011] The trained computational model is used to predict and apply the depth of the gas-liquid transition zone in the future salt cavern nitrogen dissolution cavity formation.

[0012] As a preferred solution of the method for determining the depth of the gas-liquid transition zone of the salt cavern nitrogen dissolution cavity making method of the present invention, the collection of injection data of the salt cavern cavity specifically collects the salt cavern cavity and nitrogen data that need to be calculated at present, including data on the factors that can affect the inner diameter of the technical casing and the outer diameter of the cavity making outer tube.

[0013] As a preferred solution of the method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity making method of the present invention, the preprocessing of the collected data is specifically preprocessing the collected data, including the steps of data cleaning, data smoothing and data conversion, so that the data to be used are converted into international units for modeling and analysis.

[0014] As a preferred solution of the method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity formation of the present invention, the calculation based on the collected data is specifically as follows:

[0015] The cross-sectional area of ​​the nitrogen annulus is calculated based on the numerical value set on site. The calculation formula is:

[0016]

[0017] Where A_annulus is the cross-sectional area of ​​the annulus, m 2 ; D_outer is the inner diameter of the technical casing, m; D_inner is the outer diameter of the outer tube for cavitation, m;

[0018] Next, calculate the nitrogen flow rate using the formula:

[0019] velocity = Q / A_annulus

[0020] Where velocity is the nitrogen flow rate, m / s; Q is the nitrogen flow rate, m 3 / s; A_annulus is the cross-sectional area of ​​the annulus, m 2 ;

[0021] Through iterative calculation, the pipeline is divided into grid intervals of 10 meters, and the depth, temperature, pressure, friction, nitrogen density, and nitrogen velocity in each grid are calculated until the depth reaches the cavity top. The temperature, depth, and pressure are calculated using the gradient formula. The temperature gradient coefficient is 0.02, and the compression factor is 1.16. The friction is calculated using the formula:

[0022]

[0023] Where F is the friction force, Pa; f is the Darcy-Weisbach friction coefficient, dimensionless; L is the length of the pipe, m; D is the diameter of the pipe, m; ρ is the fluid density, kg / m 3 ; v is flow velocity, m / s;

[0024] Calculate the nitrogen velocity using the formula:

[0025]

[0026] Where ρ0 is the initial nitrogen density, kg / m 3; g is the acceleration due to gravity, 9.8m / s 2 ; v0 is the initial nitrogen velocity, m / s; ρ1 is the initial nitrogen density of the next grid, kg / m 3 ; v1 is the initial nitrogen velocity of the next grid, m / s; F is the friction force, Pa;

[0027] Calculate the flow rate of nitrogen entering the chamber using the formula:

[0028]

[0029] Among them, v q is the flow rate of nitrogen in the chamber, m / s; v g is the flow rate of nitrogen in the column, m / s; L is the length of the pipeline, m; D q is the diameter of the cavity gas-liquid interface, m; A_annulus is the annulus cross-sectional area, m 2 ; π is the ratio of a circle to a circle;

[0030] Set the resistance formula to

[0031] F d =6πμrv(z)

[0032] Where, μ is the dynamic viscosity, Pa·s; r is the radius, m; L is the length of the pipe, m; v(z) is the velocity of the gas in the fluid, m / s; π is the circumference of the circle; F d for resistance;

[0033] Set the formula to the kinetic energy theorem formula

[0034]

[0035] Where m is the gas mass, kg; v is the gas velocity, m / s; d is the depth, m; F d is the resistance, N; z is the integral variable;

[0036] Assume that the ideal gas state equation is

[0037] P0V0=PV

[0038] Where P0 is standard atmospheric pressure, Pa; V0 is the volume of gas under standard atmospheric pressure, m 3 ; P is the current pressure, Pa; V is the gas volume at the current pressure, m 3 ;

[0039] Set the formula for calculating gas volume to

[0040] m=ρV

[0041] Where m is the gas mass, kg; ρ is the gas density, kg / m 3; V is the gas volume, m 3 ;

[0042] Combined with the formula, the depth of the gas-liquid transition zone is obtained. The formula for calculating the depth of the transition zone is:

[0043]

[0044] Where d is the depth, m; ρ is the gas density, kg / m 3 ; V is the gas volume, m 3 ; v is the gas velocity, m / s; π is the circumference of a circle; μ is the dynamic viscosity, Pa·s; r is the radius, m.

[0045] As a preferred solution of the method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity forming method of the present invention, the method of comparing the difference between the model prediction result and the actual gas-liquid transition zone depth and optimizing the depth of the gas-liquid transition zone is as follows:

[0046] By writing the algorithm in Python editing software, comparing the model prediction results with the actual depth data, the accuracy and predictive ability of the model are evaluated, and the parameters of the poorly performing models are tuned.

[0047] As a preferred solution of the method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity formation of the present invention, wherein: the prediction and application are specifically as follows:

[0048] The trained computational model is used to predict the depth of the gas-liquid transition zone in the future salt cavern nitrogen dissolution cavity formation, and reasonable planning and decision-making are made based on the prediction results, thereby reducing the waste of nitrogen in the nitrogen dissolution process.

[0049] In view of the above problems existing in the existing nitrogen brine removal device, the present invention is proposed.

[0050] Therefore, the object of the present invention is to provide a nitrogen brine removal device, which aims to use a block division method and an iterative calculation method to calculate the depth of the gas-liquid transition zone of the salt cavern nitrogen dissolution cavity.

[0051] In order to solve the above technical problems, the present invention provides the following technical solutions: including, the brine discharge mechanism includes a salt cavern cavity, a nitrogen component arranged on the salt cavern cavity, a first inlet and outlet component extending into the salt cavern cavity through the nitrogen component, and a second inlet and outlet pipe passing through the first inlet and outlet component.

[0052] As a preferred embodiment of the nitrogen brine removal device of the present invention, the salt cavern cavity is divided into a gas zone and a liquid zone by a boundary;

[0053] The nitrogen assembly comprises a nitrogen pipe extending through the nitrogen assembly into the salt cavern cavity and a first pipe member arranged at one end of the nitrogen pipe.

[0054] As a preferred solution of the nitrogen brine removal device of the present invention, the first inlet and outlet assembly includes a first inlet and outlet pipe extending through the nitrogen assembly into the salt cavern cavity and a second pipe member arranged at one end of the first inlet and outlet pipe.

[0055] As a preferred solution of the nitrogen brine removal device of the present invention, the second pipe can introduce objects into the first inlet and outlet pipe or export objects from the first inlet and outlet pipe;

[0056] The second inlet and outlet pipe can introduce or export objects.

[0057] The beneficial effects of the present invention are as follows: by combining relevant theoretical calculation formulas, dividing block methods and iterative calculation methods, and using Python programming tools for calculation, the depth calculation of the gas-liquid transition zone of the salt cavern nitrogen dissolution cavity can be automatically performed, which greatly improves the efficiency of solving complex engineering problems. By dividing the grid, the temperature, nitrogen flow rate, pressure and nitrogen density of different well depths are calculated, so that the calculation results are more in line with the actual results. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0059] Figure 1 It is a schematic diagram of the overall structure of on-site nitrogen brine removal in the salt cavern nitrogen dissolution cavity making gas-liquid transition zone depth determination method and device of the present invention.

[0060] Figure 2 It is a schematic diagram of the positive circulation structure of the method and device for determining the depth of the gas-liquid transition zone in the nitrogen dissolution cavity formation in salt caverns of the present invention.

[0061] Figure 3 The present invention is a schematic diagram of the reverse circulation structure of the method for determining the depth of the gas-liquid transition zone in the nitrogen dissolution cavity formation in salt caverns and the device thereof.

[0062] Figure 4 It is a schematic diagram of the process of the method and device for determining the depth of the gas-liquid transition zone in the nitrogen dissolution cavity formation in salt caverns of the present invention. DETAILED DESCRIPTION

[0063] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0064] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0065] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0066] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0067] Example 1

[0068] Reference Figure 4 , which is the first embodiment of the present invention, provides a method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity formation, the method comprising collecting injection data of the salt cavern cavity; preprocessing the collected data; performing calculations based on the collected data; comparing the difference between the model prediction result and the actual gas-liquid transition zone depth and optimizing it; using the trained calculation model to predict and apply the future depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity formation.

[0069] Specifically, they are:

[0070] S1: Collecting the injection data of the salt cavern cavity specifically involves collecting the salt cavern cavity and nitrogen data that need to be calculated, including the data of factors that can affect the inner diameter of the technical casing and the outer diameter of the cavity-making outer tube.

[0071] S2: Then, the data is cleaned and converted to convert the data into international units.

[0072] S3: Calculate the nitrogen annular cross-sectional area according to the numerical value set on site. The calculation formula is as follows:

[0073] The calculation based on the collected data is specifically as follows:

[0074] The cross-sectional area of ​​the nitrogen annulus is calculated according to the numerical value set on site. The calculation formula (1) is:

[0075]

[0076] Where A_annulus is the cross-sectional area of ​​the annulus, m 2 ; D_outer is the inner diameter of the technical cannula, m; D_inner is the outer diameter of the outer tube for cavitation, m;

[0077] Next, calculate the nitrogen flow rate, and the calculation formula (2) is:

[0078] velocity = Q / A_annulus

[0079] Where velocity is the nitrogen flow rate, m / s; Q is the nitrogen flow rate, m 3 / s; A_annulus is the cross-sectional area of ​​the annulus, m 2 ;

[0080] By iterative calculation, the pipeline is divided into grid intervals of 10 meters, and the depth, temperature, pressure, friction, nitrogen density, and nitrogen velocity in each grid are calculated until the depth reaches the cavity top. The temperature, depth, and pressure are all calculated using the gradient formula. The temperature gradient coefficient is 0.02, and the compression factor is 1.16. The friction is calculated. Formula (3) is

[0081]

[0082] Where F is the friction force, Pa; f is the Darcy-Weisbach friction coefficient, dimensionless; L is the length of the pipe, m; D is the diameter of the pipe, m; ρ is the fluid density, kg / m 3 ; v is flow velocity, m / s;

[0083] Calculate the nitrogen velocity using formula (4):

[0084]

[0085] Where ρ0 is the initial nitrogen density, kg / m 3 ; g is the acceleration due to gravity, 9.8m / s 2 ; v0 is the initial nitrogen velocity, m / s; ρ1 is the initial nitrogen density of the next grid, kg / m 3 ; v1 is the initial nitrogen velocity of the next grid, m / s; F is the friction force, Pa;

[0086] Calculate the flow rate of nitrogen entering the chamber, the calculation formula (5) is:

[0087]

[0088] Among them, v q is the flow rate of nitrogen in the chamber, m / s; v g is the flow rate of nitrogen in the column, m / s; L is the length of the pipeline, m; D q is the diameter of the cavity gas-liquid interface, m; A_annulus is the annulus cross-sectional area, m 2 ; π is the ratio of a circle to a circle;

[0089] Set the resistance formula (6) as

[0090] F d =6πμrv(z)

[0091] Where, μ is the dynamic viscosity, Pa·s; r is the radius, m; L is the length of the pipe, m; v(z) is the velocity of the gas in the fluid, m / s; π is the circumference of the circle; F d for resistance;

[0092] Assume formula (7) as the kinetic energy theorem formula

[0093]

[0094] Where m is the gas mass, kg; v is the gas velocity, m / s; d is the depth, m; F d is the resistance, N; z is the integral variable;

[0095] Assume the ideal gas state equation (8) as

[0096] P0V0=PV

[0097] Where P0 is standard atmospheric pressure, Pa; V0 is the volume of gas under standard atmospheric pressure, m 3 ; P is the current pressure, Pa; V is the gas volume at the current pressure, m 3 ;

[0098] The formula (9) for calculating gas volume is set as

[0099] m=ρV

[0100] Where m is the gas mass, kg; ρ is the gas density, kg / m 3 ; V is the gas volume, m 3 ;

[0101] Combining formulas (6), (7), (8) and (9), the depth of the gas-liquid transition zone is obtained. The formula (10) for calculating the depth of the transition zone is:

[0102]

[0103] Where d is the depth, m; ρ is the gas density, kg / m 3 ; V is the gas volume, m3 ; v is the gas velocity, m / s; π is the circumference; μ is the dynamic viscosity, Pa·s; r is the radius, m

[0104] S4: Model evaluation and tuning: By writing the algorithm in Python editing software, comparing the model prediction results with the actual depth data, the accuracy and predictive ability of the model are evaluated. For models with poor performance, parameter tuning can be performed.

[0105] S5: Prediction and application: The trained computational model can be used to predict the depth of the gas-liquid transition zone in the future nitrogen dissolution process in salt caverns. Reasonable planning and decision-making can be made based on the prediction results, thereby reducing the waste of nitrogen in the nitrogen dissolution process.

[0106] During use, the salt cavern cavity and nitrogen data currently required to be calculated in step S1 may include the inner diameter of the technical casing, the outer diameter of the outer cavity pipe, the inner diameter of the outer cavity pipe, the outer diameter of the inner cavity pipe, the wellhead temperature, the nitrogen injection rate, the dynamic viscosity of nitrogen, the brine density, the nitrogen molar mass, the nitrogen compression factor, the brine viscosity, the depth of the outer cavity pipe, the brine return wellhead pressure, the cavity top depth, the air cushion thickness at the bottom of the cavity top, the injected fresh water displacement, and the data of the influencing factors related to the cavity gas-liquid interface diameter.

[0107] Example 2

[0108] Reference Figures 1 to 4 , which is the second embodiment of the present invention. This embodiment is different from the first embodiment in that: the experiment is carried out according to Example 1.

[0109] The experiment was conducted based on the following first basic data:

[0110]

[0111]

[0112] Table 1 Basic data table of the first experiment

[0113] The calculation is performed according to the method steps S1 to S5 of Example 1.

[0114] The result is:

[0115]

[0116] Table 2 Calculation results of the first experiment

[0117] Through the first test, it can be clearly concluded that the depth should be 2.04m when the brine is discharged through positive circulation, and the depth should be 3.70m when the brine is discharged through reverse circulation, and the corresponding depth of the gas-liquid transition zone of the nitrogen dissolution cavity in the salt cavern can be calculated.

[0118] The experiment was conducted based on the following second basic data:

[0119]

[0120]

[0121] Table 3 Basic data table of the second experiment

[0122] The calculation is performed according to the method steps S1 to S5 of Example 1.

[0123] The result is:

[0124]

[0125] Table 4 Calculation results of the second experiment

[0126] Compared with Example 1, further, through the second test, it can be clearly concluded that when the positive circulation brine is discharged, the depth should be 10.18m, and when the reverse circulation brine is discharged, the depth should be 18.45m, and the corresponding depth of the gas-liquid transition zone of the salt cavern nitrogen dissolution cavity is calculated.

[0127] The remaining structures are the same as those of Example 1.

[0128] Example 3

[0129] Reference Figures 1 to 3 , which is the third embodiment of the present invention. This embodiment is different from the second embodiment in that: a brine discharge device includes a salt cavern cavity 101, a nitrogen component 102 arranged on the salt cavern cavity 101, a first inlet and outlet component 103 extending into the salt cavern cavity 101 through the nitrogen component 102, and a second inlet and outlet pipe 104 passing through the first inlet and outlet component 103.

[0130] Compared with Example 2, reference Figure 1 During the on-site nitrogen dissolution cavity making process, the first inlet and outlet component 103 is used as a brine discharge pipe. When the nitrogen component 102 is filled with nitrogen N, about ten meters below the gas-liquid interface under the first inlet and outlet component 103, nitrogen bubbles N' will still be discharged from the first inlet and outlet component 103, resulting in a waste of nitrogen resources and an increase in nitrogen costs. If the depth is too low, the resources of the first inlet and outlet component 103 will be wasted and more resources will be required to complete the brine discharge process.

[0131] Further, according to the method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity, refer to Figure 2The salt cavern cavity 101 is divided into a gas zone 101c and a liquid zone 101a by a boundary 101b; the nitrogen assembly 102 includes a nitrogen pipe 102a extending through the nitrogen assembly 102 to the salt cavern cavity 101 and a first pipe fitting 102b arranged at one end of the nitrogen pipe 102a; the first inlet and outlet assembly 103 includes a first inlet and outlet pipe 103a extending through the nitrogen assembly 102 to the salt cavern cavity 101 and a second pipe fitting 103b arranged at one end of the first inlet and outlet pipe 103a.

[0132] By determining the dividing point 101b, nitrogen N is filled into the first pipe 102b, and the nitrogen N enters the liquid area 101a through the nitrogen pipe 102a and then enters the gas area 101c, and fresh water F is filled into the second inlet and outlet pipe 104, so that the brine B can be discharged from the second pipe 103b through the first inlet and outlet pipe 103a.

[0133] Similarly, reference Figure 3 , by charging nitrogen N toward the first pipe 102b, the nitrogen N enters the liquid area 101a and then enters the gas area 101c through the nitrogen pipe 102a, and charging fresh water F into the second pipe 103b, the fresh water F is driven to enter the liquid area 101a through the first inlet and outlet pipe 103a. In this process, the brine B can be discharged through the second inlet and outlet pipe 104. By using the salt caverns with different depths, pressures, temperatures, annular space areas, gas velocities, gas densities, and cavity diameters divided into the liquid area 101a and the gas area 101c and the salt cavern nitrogen dissolution cavity gas-liquid transition zone depth determination method, considering the economic factors, the salt cavern nitrogen dissolution cavity gas-liquid transition zone depth is calculated, and a more accurate and economical brine discharge pipe placement plan can be provided.

[0134] The remaining structure is the same as that of Example 2.

[0135] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to several modifications still falling within the scope of the appended claims.

[0136] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0137] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for determining the depth of the gas-liquid transition zone in a salt cavern nitrogen dissolution cavity, characterized in that: include, Collect injection data from salt cavern cavities; Preprocess the collected data; Make calculations based on the data collected; By comparing the model prediction results with the actual gas-liquid transition zone depth and optimizing; The trained computational model is used to predict and apply the depth of the gas-liquid transition zone in the future salt cavern nitrogen dissolution cavity formation.

2. The method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity making process according to claim 1 is characterized in that: The collecting of the injection data of the salt cavern cavity specifically involves collecting the salt cavern cavity and nitrogen data currently required to be calculated, including data of factors that can affect the inner diameter of the technical casing and the outer diameter of the cavity-making outer tube.

3. The method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity making process according to claim 2 is characterized in that: The preprocessing of the collected data specifically refers to preprocessing the collected data, including the steps of data cleaning, data smoothing and data conversion, so that the data to be used are converted into international units for modeling and analysis.

4. The method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity making process according to any one of claims 1 to 3, characterized in that: The calculation based on the collected data is specifically as follows: The cross-sectional area of ​​the nitrogen annulus is calculated according to the numerical value set on site. The calculation formula (1) is: Where A_annulus is the cross-sectional area of ​​the annulus, m 2 ; D_outer is the inner diameter of the technical cannula, m; D_inner is the outer diameter of the outer tube for cavitation, m; Next, calculate the nitrogen flow rate, and the calculation formula (2) is: velocity = Q / A_annulus Where velocity is the nitrogen flow rate, m / s; Q is the nitrogen flow rate, m 3 / s; A_annulus is the cross-sectional area of ​​the annulus, m 2 ; By iterative calculation, the pipeline is divided into grid intervals of 10 meters, and the depth, temperature, pressure, friction, nitrogen density, and nitrogen velocity in each grid are calculated until the depth reaches the cavity top. The temperature, depth, and pressure are all calculated using the gradient formula. The temperature gradient coefficient is 0.02, and the compression factor is 1.

16. The friction is calculated. Formula (3) is Where F is the friction force, Pa; f is the Darcy-Weisbach friction coefficient, dimensionless; L is the length of the pipe, m; D is the diameter of the pipe, m; ρ is the fluid density, kg / m 3 ; v is flow velocity, m / s; Calculate the nitrogen velocity using formula (4): Where ρ0 is the initial nitrogen density, kg / m 3 ; g is the acceleration due to gravity, 9.8m / s 2 ; v0 is the initial nitrogen velocity, m / s; ρ1 is the initial nitrogen density of the next grid, kg / m 3 ; v1 is the initial nitrogen velocity of the next grid, m / s; F is the friction force, Pa; Calculate the flow rate of nitrogen entering the chamber, the calculation formula (5) is: Among them, v q is the flow rate of nitrogen in the chamber, m / s; v g is the flow rate of nitrogen in the column, m / s; L is the length of the pipeline, m; D q is the diameter of the cavity gas-liquid interface, m; A_annulus is the annulus cross-sectional area, m 2 ; π is the ratio of a circle to a circle; Set the resistance formula (6) as F d =6πur(z) Where, μ is the dynamic viscosity, Pa·s; r is the radius, m; L is the length of the pipe, m; v(z) is the velocity of the gas in the fluid, m / s; π is the circumference of the circle; F d for resistance; Assume formula (7) as the kinetic energy theorem formula Where m is the gas mass, kg; v is the gas velocity, m / s; d is the depth, m; F d is the resistance, N; z is the integral variable; Assume the ideal gas state equation (8) as P0V0=PV Where P0 is standard atmospheric pressure, Pa; V0 is the volume of gas under standard atmospheric pressure, m 3 ; P is the current pressure, Pa; V is the gas volume at the current pressure, m 3 ; The formula (9) for calculating gas volume is set as m=ρV Where m is the gas mass, kg; ρ is the gas density, kg / m 3 ; V is the gas volume, m 3 ; Combining formulas (6), (7), (8) and (9), the depth of the gas-liquid transition zone is obtained. The formula (10) for calculating the depth of the transition zone is: Where d is the depth, m; ρ is the gas density, kg / m 3 ; V is the gas volume, m 3 ; v is the gas velocity, m / s; π is the circumference of a circle; μ is the dynamic viscosity, Pa·s; r is the radius, m.

5. The method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity making process according to claim 4 is characterized in that: The method of comparing the difference between the model prediction result and the actual gas-liquid transition zone depth and optimizing it is as follows: By writing the algorithm in Python editing software, comparing the model prediction results with the actual depth data, the accuracy and predictive ability of the model are evaluated, and the parameters of the poorly performing models are tuned.

6. The method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity making process according to claim 5 is characterized in that: The prediction and application are specifically as follows: The trained computational model is used to predict the depth of the gas-liquid transition zone in the future salt cavern nitrogen dissolution cavity formation, and reasonable planning and decision-making are made based on the prediction results, thereby reducing the waste of nitrogen in the nitrogen dissolution process.

7. A nitrogen brine removal device, characterized in that: The method for determining the depth of the gas-liquid transition zone in the salt cavern nitrogen dissolution cavity formation as described in any one of claims 1 to 6 further includes: The brine discharge mechanism (100) comprises a salt cavern cavity (101), a nitrogen assembly (102) arranged on the salt cavern cavity (101), a first inlet and outlet assembly (103) extending through the nitrogen assembly (102) into the salt cavern cavity (101), and a second inlet and outlet pipe (104) passing through the first inlet and outlet assembly (103).

8. The nitrogen brine removal device according to claim 7, characterized in that: The salt cavern cavity (101) is divided into a gas zone (101c) and a liquid zone (101a) via a boundary (101b); The nitrogen component (102) comprises a nitrogen pipe (102a) passing through the nitrogen component (102) and extending into the salt cavern cavity (101), and a first pipe member (102b) arranged at one end of the nitrogen pipe (102a).

9. The nitrogen brine removal device according to claim 8, characterized in that: The first inlet and outlet assembly (103) comprises a first inlet and outlet pipe (103a) passing through the nitrogen assembly (102) and extending into the salt cavern chamber (101), and a second pipe (103b) arranged at one end of the first inlet and outlet pipe (103a).

10. The nitrogen brine removal device according to claim 9, characterized in that: The second pipe (103b) is capable of introducing objects into the first inlet and outlet pipe (103a) or exporting objects from the first inlet and outlet pipe (103a); The second inlet and outlet pipe (104) is capable of introducing or exporting objects.

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