Leakage rate quantitative evaluation method and system for salt cavern hydrogen / helium storage reservoir in gas injection and reservoir building period

Abstract

The invention discloses a quantitative evaluation method and system for the leakage rate of a salt cavern hydrogen / helium storage reservoir in a gas injection and reservoir building period. The method comprises the following steps: S1, acquiring basic data of the salt cavern hydrogen / helium storage reservoir; s2, monitoring and recording wellhead pressure, gas injection flow and gas injection temperature data during the gas injection reservoir building period in real time; s3, performing numerical simulation on the temperature field of hydrogen / helium in the reservoir, the creep law of the cavity and the dissolution dynamic state of hydrogen / helium by using the basic data and the real-time monitoring data of the salt cavern hydrogen / helium reservoir, so as to realize quantitative evaluation of the leakage rate; by accurately predicting four factors of hydrogen / helium leakage, hydrogen / helium dissolution, gas heat effect and cavity shrinkage, the leakage rate of hydrogen / helium can be inversely calculated in real time, and feasibility evaluation of the initial stage of hydrogen / helium reservoir construction and leakage prediction in an operation cycle with high precision requirements are realized; and the important demand on hydrogen / helium leakage rate prediction during the salt cavern hydrogen / helium storage reservoir building period is met.

Description

Technical Field

[0001] The present application relates to the technical field of underground storage of rare gases such as hydrogen and helium, and in particular to a method and system for quantitatively evaluating the leakage rate of a salt cavern hydrogen and helium storage reservoir during the gas injection and storage construction period. Background Art

[0002] Hydrogen / helium, as a strategic scarce substance, is widely used as a pressurizing agent and booster for rocket liquid fuel, a coolant for the nuclear industry, and a leak detector for pipelines and electronic and electrical devices. Salt rock formations are excellent geological bodies for deep earth energy storage, with low permeability (less than 10 -20 m 2 ) and small porosity (less than 1%), existing research has demonstrated the technical feasibility of storing hydrogen / helium in salt rock formations.

[0003] In the prior art, nitrogen is used to test the air tightness of salt cavern natural gas reservoirs during their construction. However, compared to nitrogen, hydrogen / helium molecules are smaller. Under the same operating pressure, the permeation and diffusion losses of hydrogen / helium are greater, and the air tightness of nitrogen is not completely equivalent to that of hydrogen / helium. At the same time, the market unit price of hydrogen / helium is between 100 and 500 yuan per cubic meter, which is much higher than the price of natural gas. Even a small leak will cause a large economic loss to the owner. Therefore, the acceptable leakage threshold for natural gas reservoirs is obviously no longer reasonable in hydrogen / helium reservoirs. However, the current leakage rate assessment still uses the evaluation method of traditional natural gas reservoirs, focusing on the feasibility evaluation in the early stage of reservoir construction and the prediction of leakage during the operation cycle. It is obviously no longer applicable to hydrogen / helium and the gas injection construction period with higher precision requirements, and no relevant patents have been disclosed. At present, there is no relevant technology for gas tightness detection using hydrogen / helium during the construction of salt cavern natural gas reservoirs. Therefore, there is an urgent need for a quantitative leakage rate assessment method for salt cavern hydrogen / helium storage during the gas injection construction period that can meet high-precision requirements. Summary of the invention

[0004] In order to solve the above problems, the present application provides a method and system for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage reservoir during the gas injection and construction period, which realizes the feasibility evaluation of the initial stage of hydrogen / helium storage construction with high precision and the prediction of leakage during the operation cycle, and meets the significant demand for hydrogen / helium leakage rate prediction during the construction of a salt cavern hydrogen / helium storage reservoir. The technical solution is as follows:

[0005] The present application provides a method for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage reservoir during the gas injection and storage construction period, comprising the following steps:

[0006] S1 obtains basic data of salt cavern hydrogen / helium storage;

[0007] S2 monitors and records the wellhead pressure, gas injection flow rate and gas injection temperature data in real time during gas injection and reservoir construction;

[0008] S3 uses the basic data and real-time monitoring data of salt cavern hydrogen / helium storage to numerically simulate the temperature field of hydrogen / helium in the storage, the creep law of the cavity, and the dissolution dynamics of hydrogen / helium, thereby achieving quantitative evaluation of the leakage rate.

[0009] 3. For example, in the method for quantitatively evaluating the leakage rate of the salt cavern hydrogen / helium storage during the gas injection and storage construction period provided in one embodiment, in S3, the quantitative evaluation of the hydrogen / helium leakage rate includes calculating the leakage amount of hydrogen / helium, and the calculation method of the hydrogen / helium leakage amount is:

[0010] n L =n0-n k -n r Formula (1);

[0011] In formula (1), n L is the leakage of hydrogen / helium, n0 is the cumulative injection volume of hydrogen / helium; n r is the dissolved amount of hydrogen / helium; n k It is the storage capacity of hydrogen / helium in the current chamber.

[0012] For example, in the method for quantitatively evaluating the leakage rate of the salt cavern hydrogen / helium storage during the gas injection and storage period provided in one embodiment, the current storage amount of hydrogen / helium in the cavity n k The calculation method is:

[0013]

[0014] In formula (2), V is the volume of the salt cavern; ΔV is the measured volume shrinkage; T f is the temperature of hydrogen / helium; p is the pressure of hydrogen / helium; Z is the compression factor of hydrogen / helium; R is the gas constant;

[0015] By combining equations (1) and (2), the hydrogen / helium leakage rate can be calculated.

[0016] For example, in the method for quantitatively evaluating the leakage rate of the salt cavern hydrogen / helium storage during the gas injection and storage construction period provided in one embodiment, in S3, the dynamic numerical simulation of hydrogen / helium dissolution is to predict the dissolution amount of hydrogen / helium, and the diffusion and dissolution of hydrogen / helium in brine is obtained according to the diffusion law to satisfy the following formula:

[0017]

[0018] In formula (3), c is the concentration of hydrogen / helium in brine; D is the diffusion coefficient of hydrogen / helium in brine;

[0019] Based on formula (3), the concentration distribution of hydrogen / helium in brine at different times can be simulated, and the dissolved amount of hydrogen / helium n can be calculated by volume integration of the following formula:r :

[0020]

[0021] For example, in the method for quantitatively evaluating the leakage rate of the salt cavern hydrogen / helium storage during the gas injection and storage period provided in one embodiment, the creep law of the cavity in S3 is used to predict the volume shrinkage of the salt cavern hydrogen / helium storage, and the calculation method is:

[0022]

[0023] In formula (5), V is the volume of the salt cavern; ΔV is the measured volume shrinkage; x is the creep rate attenuation index, which can be obtained through the core creep test of the target layer of the hydrogen / helium storage reservoir; a is the empirical coefficient, which can be obtained by inverting the measured cavity volume shrinkage data.

[0024] For example, in the method for quantitatively evaluating the leakage rate of the salt cavern hydrogen / helium storage during the gas injection and storage construction period provided in one embodiment, in S3, the temperature field prediction method of hydrogen / helium is:

[0025]

[0026] In formula (6), A is the cross-sectional area of ​​the wellbore or salt cavern; ρ is the density of hydrogen / helium; C v,g is the specific heat capacity of hydrogen / helium; T f is the temperature of hydrogen / helium; t is the time; μ jT is the Joule-Thomson coefficient of hydrogen / helium; p is the pressure of hydrogen / helium; Q e is the convective heat transfer rate between hydrogen / helium and surrounding rock, Q e The calculation method is:

[0027] Q e =2πr0U we (T e -T f ) Formula (7);

[0028] In formula (7), r0 is the radius of the wellbore or salt cavern; U we is the comprehensive heat transfer coefficient between the gas and the surrounding environment; T e is the formation temperature, T e The calculation method is:

[0029]

[0030] In formula (8), r is the distance from the center of the gas storage; ρ e is the density of the formation rock; C e is the specific heat capacity of the formation rock; k e is the thermal conductivity of the formation rock;

[0031] The comprehensive heat transfer coefficient between the gas and the surrounding environment is U we The calculation method is:

[0032]

[0033] In formula (9), h t is the heat transfer coefficient of hydrogen / helium; r to 、r co 、r ci 、r ces are the outer diameter of the injection and production string, the inner and outer diameters of the casing, and the outer diameter of the cement sheath; k cas and k ces is the thermal conductivity of casing and cement sheath;

[0034] By combining equations (6) to (9), the change of hydrogen / helium temperature in the chamber with time during the gas injection and reservoir construction period can be calculated.

[0035] The second aspect of the present application provides a leakage rate quantitative evaluation system for a salt cavern hydrogen / helium storage reservoir during the gas injection and storage construction period, comprising:

[0036] Basic data collection unit, used to collect basic data of salt cavern hydrogen / helium storage;

[0037] Real-time monitoring unit, used to monitor and record the wellhead pressure, gas injection flow rate and gas injection temperature data during gas injection and reservoir construction in real time;

[0038] The leakage rate quantitative assessment unit uses the basic data and real-time monitoring data of the salt cavern hydrogen / helium storage to numerically simulate the temperature field of hydrogen / helium in the storage, the creep law of the cavity, and the hydrogen / helium dissolution dynamics, and quantitatively assesses the leakage rate of the salt cavern hydrogen / helium storage through the measured wellhead pressure data.

[0039] For example, in the leakage rate quantitative assessment system of the salt cavern hydrogen / helium storage during the gas injection and storage construction period provided in one embodiment, the basic data collected by the basic data collection unit is basic data for quantitative assessment of the leakage rate of the salt cavern hydrogen / helium storage, including sonar cavity measurement data of the salt cavern cavity, wellbore trajectory, wellbore structure and gas injection string size.

[0040] For example, in the leakage rate quantitative assessment system of the salt cavern hydrogen / helium storage during the gas injection and storage construction period provided in one embodiment, the real-time monitoring unit includes a gas flow meter, a gas thermometer and a wellhead pressure gauge arranged on the ground injection and production manifold to monitor and store the wellhead pressure, gas injection flow rate and gas injection temperature in real time.

[0041] For example, in the leakage rate quantitative assessment system for the salt cavern hydrogen / helium storage during the gas injection and storage construction period provided in one embodiment, the data monitored and recorded by the real-time monitoring unit is transmitted to a data receiver via Bluetooth, and the measured data is transmitted to the leakage rate quantitative assessment unit via the data receiver for permeability quantitative assessment.

[0042] The beneficial effects of a method and system for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage during the gas injection and storage construction period provided in some embodiments of the present application are as follows: the present application can accurately predict four factors, namely, hydrogen / helium leakage, hydrogen / helium dissolution, gas thermal effect, and cavity shrinkage, and then can back-calculate the hydrogen / helium leakage rate in real time, thereby achieving a high-precision feasibility evaluation of the initial stage of hydrogen / helium storage construction and a leakage prediction during the operation cycle. The evaluation method of the present application, supported by a complete theoretical model, is complementary to the real-time data of on-site monitoring, and is simple in calculation, scientific and reasonable, meeting the significant demand for hydrogen / helium leakage rate prediction during the gas injection and storage construction period, and can provide technical support for the optimal design of the surface injection and production process of the salt cavern hydrogen / helium storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 This is a schematic diagram of the structure of the leakage rate quantitative evaluation system during the gas injection and storage period of the salt cavern hydrogen / helium storage in the present application;

[0045] Figure 2 This is a flow chart of the method for quantitatively evaluating the leakage rate of the salt cavern hydrogen / helium storage during the gas injection and storage construction period of the present application. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0048] like Figure 1 As shown, when the salt cavern hydrogen / helium storage is built by gas injection, the gas injection string 6 is the connection channel between the hydrogen / helium tanker 1 and the helium storage cavity 7; the high-pressure hydrogen / helium is injected into the helium storage cavity 7 through the gas injection string 6 by the hydrogen / helium tanker 1, and the brine 9 in the cavity is squeezed out through the brine discharge string 5. After hydrogen / helium is injected into the salt cavern, the change of the wellhead pressure is mainly affected by four factors: hydrogen / helium leakage, hydrogen / helium dissolution, hydrogen / helium temperature change and cavity shrinkage. If the hydrogen / helium dissolution, hydrogen / helium temperature recovery and cavity shrinkage can be accurately predicted, the hydrogen / helium leakage rate can be reversed in real time.

[0049] In view of this, the present application provides a method for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage reservoir during the gas injection and storage construction period, such as Figure 2 As shown, the following steps are included:

[0050] S1 obtains basic data of salt cavern hydrogen / helium storage;

[0051] Specifically, it includes collecting basic data on salt cavern hydrogen / helium storage, such as sonar cavity morphology, wellbore structure, wellbore trajectory, and injection and production string dimensions;

[0052] S2 monitors and records the wellhead pressure, gas injection flow rate and gas injection temperature data in real time during gas injection and reservoir construction;

[0053] S3 uses the basic data and real-time monitoring data of salt cavern hydrogen / helium storage to numerically simulate the temperature field of hydrogen / helium in the storage, the creep law of the cavity, and the dissolution dynamics of hydrogen / helium, thereby achieving quantitative evaluation of the leakage rate.

[0054] Compared with traditional salt cavern natural gas storage, the quantitative evaluation method of leakage rate of salt cavern hydrogen / helium storage during the gas injection and storage construction period of the present application is aimed at the gas injection and storage construction stage of salt cavern hydrogen / helium storage, and can provide technical means for the fine evaluation of leakage rate of salt cavern hydrogen / helium storage. The evaluation method of the present application is supported by a perfect theoretical model and complements the real-time data of on-site monitoring. The calculation is simple and scientific.

[0055] For example, in the method for quantitatively evaluating the leakage rate of the salt cavern hydrogen / helium storage during the gas injection and storage period provided in one embodiment, in S3, the quantitative evaluation of the hydrogen / helium leakage rate includes calculating the leakage amount of hydrogen / helium. According to the principle of conservation of mass, the leakage amount of hydrogen / helium is equal to the amount injected into the cavity minus the amount dissolved minus the storage amount in the current cavity, and the expression is:

[0056] n L =n0-n k -n r Formula (1);

[0057] In formula (1), n L is the leakage of hydrogen / helium, n0 is the cumulative injection volume of hydrogen / helium; n r is the dissolved amount of hydrogen / helium; n k It is the storage capacity of hydrogen / helium in the current chamber.

[0058] The current storage volume of hydrogen / helium in the chamber n k The calculation method is:

[0059]

[0060] In formula (2), V is the volume of the salt cavern; ΔV is the measured volume shrinkage; T f is the temperature of hydrogen / helium; p is the pressure of hydrogen / helium; Z is the compression factor of hydrogen / helium; R is the gas constant;

[0061] By combining equations (1) and (2), the hydrogen / helium leakage rate can be calculated.

[0062] The dissolution of hydrogen / helium in brine is a diffusion dissolution process, and the hydrogen / helium concentration at the gas-brine interface 8 tends to be saturated. For example, in the quantitative evaluation method of the leakage rate of the salt cavern hydrogen / helium storage during the gas injection and storage period provided in one embodiment, in S3, the dynamic numerical simulation of hydrogen / helium dissolution is to predict the dissolution amount of hydrogen / helium, and the diffusion dissolution of hydrogen / helium in brine is obtained according to the diffusion law to satisfy the following formula:

[0063]

[0064] In formula (3), c is the concentration of hydrogen / helium in brine; D is the diffusion coefficient of hydrogen / helium in brine;

[0065] Based on formula (3), the concentration distribution of hydrogen / helium in brine at different times can be simulated, and the dissolved amount of hydrogen / helium n can be calculated by volume integration of the following formula: r :

[0066]

[0067] Since the operating pressure of the salt cavern hydrogen / helium storage is less than the in-situ geostress of the formation, the surrounding rock of the hydrogen / helium storage will inevitably shrink, resulting in a reduction in the cavity volume. The reduction in cavity volume will squeeze the hydrogen / helium gas, resulting in an increase in wellhead pressure. Although there are individual differences between salt caverns, the volume shrinkage rate of salt cavern reservoirs in the same area is basically the same. Therefore, the historical volume shrinkage data of other salt cavern gas storages that have been put into production can be used to predict the volume shrinkage rate of the hydrogen / helium storage. For example, in the quantitative evaluation method of the leakage rate of the salt cavern hydrogen / helium storage during the gas injection and storage period provided in one embodiment, the creep law of the cavity in S3 is used to predict the volume shrinkage of the salt cavern hydrogen / helium storage, and the calculation method is:

[0068]

[0069] In formula (5), V is the volume of the salt cavern; ΔV is the measured volume shrinkage; x is the creep rate attenuation index, which can be obtained through the core creep test of the target layer of the hydrogen / helium storage reservoir; a is the empirical coefficient, which can be obtained by inverting the measured cavity volume shrinkage data. After determining the creep rate attenuation index x and the empirical coefficient a, the volume shrinkage ΔV of the cavity at any time can be predicted.

[0070] In the closed storage space, the heat transfer mode between hydrogen / helium and the salt cavern surrounding rock and the wellbore is heat conduction. For example, in the quantitative evaluation method of the leakage rate of the salt cavern hydrogen / helium storage during the gas injection and storage construction period provided in one embodiment, in S3, the temperature field prediction method of hydrogen / helium is:

[0071]

[0072] In formula (6), A is the cross-sectional area of ​​the wellbore or salt cavern; ρ is the density of hydrogen / helium; C v,g is the specific heat capacity of hydrogen / helium; T f is the temperature of hydrogen / helium; t is the time; μ jT is the Joule-Thomson coefficient of hydrogen / helium; p is the pressure of hydrogen / helium; Q e is the convective heat transfer rate between hydrogen / helium and surrounding rock, which is the fundamental reason for the increase in hydrogen / helium temperature. e The calculation method is:

[0073] Q e =2πr0U we(T e -T f ) Formula (7);

[0074] In formula (7), r0 is the radius of the wellbore or salt cavern; U we is the comprehensive heat transfer coefficient between the gas and the surrounding environment; T e is the formation temperature, T e The calculation method is:

[0075]

[0076] In formula (8), r is the distance from the center of the gas storage; ρ e is the density of the formation rock; C e is the specific heat capacity of the formation rock; k e is the thermal conductivity of the formation rock;

[0077] The comprehensive heat transfer coefficient between the gas and the surrounding environment is U we Related to the casing and cement sheath structures and their thermophysical parameters, the calculation method is:

[0078]

[0079] In formula (9), h t is the heat transfer coefficient of hydrogen / helium; r to 、r co 、r ci 、r ces are the outer diameter of the injection and production string, the inner and outer diameters of the casing, and the outer diameter of the cement sheath; k cas and k ces is the thermal conductivity of casing and cement sheath;

[0080] By combining equations (6) to (9), the change of hydrogen / helium temperature in the chamber with time during the gas injection and reservoir construction period can be calculated.

[0081] In summary, the hydrogen / helium leakage rate can be calculated.

[0082] The quantitative evaluation method for the leakage rate of a salt cavern hydrogen / helium storage reservoir during the gas injection and reservoir construction period of the present application utilizes the basic data and real-time status monitoring data of the salt cavern hydrogen / helium storage reservoir to numerically simulate the hydrogen / helium leakage, hydrogen / helium dissolution, hydrogen / helium temperature change and cavity shrinkage in the reservoir. By quantitatively characterizing the influence of the above four effects on the change of wellhead pressure, the hydrogen / helium leakage rate can be back-calculated in real time.

[0083] The second aspect of the present application provides a system for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage reservoir during the gas injection and storage construction period, such as Figure 1 As shown, including:

[0084] Basic data collection unit, used to collect basic data of salt cavern hydrogen / helium storage;

[0085] The real-time monitoring unit is used to monitor and record the wellhead pressure, gas injection flow rate and gas injection temperature data during the gas injection and reservoir construction period in real time, including a gas flow meter 2, a gas thermometer 3, a wellhead pressure gauge 4 and a data receiver 10, and is used to monitor and store the wellhead pressure, gas injection flow rate and gas injection temperature in real time; specifically, the gas flow meter 2, the gas thermometer 3 and the wellhead pressure gauge 4 are installed on the ground injection and production manifold of the gas injection string 6, and are transmitted to the data receiver 10 via Bluetooth, and the measured data is transmitted to the leakage rate quantitative evaluation unit 11 for quantitative leakage rate evaluation.

[0086] The leakage rate quantitative evaluation unit 11 uses the basic data and real-time monitoring data of the salt cavern hydrogen / helium storage to numerically simulate the temperature field of hydrogen / helium in the storage, the creep law of the cavity, and the hydrogen / helium dissolution dynamics, and quantitatively evaluates the leakage rate of the salt cavern hydrogen / helium storage through the measured wellhead pressure data.

[0087] The leakage rate quantitative evaluation system of the salt cavern hydrogen / helium storage during the gas injection and storage construction period of the present application monitors and stores the wellhead pressure, gas injection flow rate and gas injection temperature in real time through a real-time monitoring unit, and quantitatively simulates the four effects of hydrogen / helium leakage, hydrogen / helium dissolution, hydrogen / helium temperature change and cavity shrinkage through a leakage rate quantitative evaluation unit 11, and finally calculates the hydrogen / helium leakage rate.

[0088] Compared with traditional technical means, the present application provides a method and system for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage tank during the gas injection and storage construction period. This method, supported by a complete theoretical model, is complementary to the real-time data of on-site monitoring. The calculation is simple, scientific and reasonable, and meets the significant demand for hydrogen / helium leakage rate prediction during the gas injection and storage construction period. It can provide technical support for the optimal design of the surface injection and production process of salt cavern hydrogen / helium storage tanks.

[0089] Although the implementation scheme of the present application has been disclosed as above, it is not limited to the applications listed in the specification and implementation modes, and it can be fully applicable to various fields suitable for the present application. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present application is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage reservoir during the gas injection and storage period, characterized in that: The following steps are involved: S1 obtains basic data of salt cavern hydrogen / helium storage; S2 monitors and records the wellhead pressure, gas injection flow rate and gas injection temperature data in real time during gas injection and reservoir construction; S3 uses the basic data and real-time monitoring data of salt cavern hydrogen / helium storage to numerically simulate the temperature field of hydrogen / helium in the storage, the creep law of the cavity, and the dissolution dynamics of hydrogen / helium, thereby achieving quantitative evaluation of the leakage rate.

2. The method for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage during the gas injection and storage period according to claim 1, characterized in that: In S3, the quantitative evaluation of the hydrogen / helium leakage rate includes calculating the hydrogen / helium leakage amount, and the calculation method of the hydrogen / helium leakage amount is: n L = n0 - n k -n r Equation (1); In formula (1), n L is the leakage of hydrogen / helium, n0 is the cumulative injection volume of hydrogen / helium; n r is the dissolved amount of hydrogen / helium; n k is the storage capacity of hydrogen / helium in the current chamber.

3. The method for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage during the gas injection and storage period according to claim 2, characterized in that: The current storage volume of hydrogen / helium in the chamber n k The calculation method is: In formula (2), V is the volume of the salt cavern; ΔV is the measured volume shrinkage; T f is the temperature of hydrogen / helium; p is the pressure of hydrogen / helium; Z is the compression factor of hydrogen / helium; R is the gas constant; By combining equations (1) and (2), the hydrogen / helium leakage rate can be calculated.

4. The method for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage during the gas injection and storage period according to claim 3 is characterized in that: In S3, the dynamic numerical simulation of hydrogen / helium dissolution is to predict the amount of hydrogen / helium dissolved, and the diffusion and dissolution of hydrogen / helium in brine is obtained according to the diffusion law to satisfy the following formula: In formula (3), c is the concentration of hydrogen / helium in brine; D is the diffusion coefficient of hydrogen / helium in brine; Based on formula (3), the concentration distribution of hydrogen / helium in brine at different times can be simulated, and the dissolved amount of hydrogen / helium n can be calculated by volume integration of the following formula: r :

5. The method for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage during the gas injection and storage period according to claim 4, characterized in that: The creep law of the cavity in S3 is used to predict the volume shrinkage of the salt cavern hydrogen / helium storage reservoir, and the calculation method is: In formula (5), V is the volume of the salt cavern; ΔV is the measured volume shrinkage; x is the creep rate attenuation index, which can be obtained through the core creep test of the target layer of the hydrogen / helium storage reservoir; a is the empirical coefficient, which can be obtained by inverting the measured cavity volume shrinkage data.

6. The method for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage during the gas injection and storage period according to claim 5 is characterized in that: In S3, the temperature field prediction method of hydrogen / helium is: In formula (6), A is the cross-sectional area of ​​the wellbore or salt cavern; ρ is the density of hydrogen / helium; C v,g is the specific heat capacity of hydrogen / helium; T f is the temperature of hydrogen / helium; t is the time; μ jT is the Joule-Thomson coefficient of hydrogen / helium; p is the pressure of hydrogen / helium; Q e is the convective heat transfer rate between hydrogen / helium and surrounding rock, Q e The calculation method is: Q e =2πr0U we (T e -T f ) Formula (7); In formula (7), r0 is the radius of the wellbore or salt cavern; U we is the comprehensive heat transfer coefficient between the gas and the surrounding environment; T e is the formation temperature, T e The calculation method is: In formula (8), r is the distance from the center of the gas storage; ρ e is the density of the formation rock; C e is the specific heat capacity of the formation rock; k e is the thermal conductivity of the formation rock; The comprehensive heat transfer coefficient between the gas and the surrounding environment is U we The calculation method is: In formula (9), h t is the heat transfer coefficient of hydrogen / helium; r to 、r co 、r ci 、r ces are the outer diameter of the injection and production string, the inner and outer diameters of the casing, and the outer diameter of the cement sheath; k cas and k ces is the thermal conductivity of casing and cement sheath; By combining equations (6) to (9), the change of hydrogen / helium temperature in the chamber with time during the gas injection and reservoir construction can be calculated.

7. A system for quantitatively evaluating the leakage rate of a salt cavern hydrogen / helium storage during the gas injection and storage period, characterized in that: include: Basic data collection unit, used to collect basic data of salt cavern hydrogen / helium storage; Real-time monitoring unit, used to monitor and record the wellhead pressure, gas injection flow rate and gas injection temperature data during gas injection and reservoir construction in real time; The leakage rate quantitative assessment unit uses the basic data and real-time monitoring data of the salt cavern hydrogen / helium storage to numerically simulate the temperature field of hydrogen / helium in the storage, the creep law of the cavity, and the hydrogen / helium dissolution dynamics, and quantitatively assesses the leakage rate of the salt cavern hydrogen / helium storage through the measured wellhead pressure data.

8. The leakage rate quantitative evaluation system of the salt cavern hydrogen / helium storage during the gas injection and storage period according to claim 7, characterized in that: The basic data collected by the basic data collection unit are basic data for quantitative evaluation of salt cavern hydrogen / helium storage leakage rate, including sonar cavity measurement data of the salt cavern cavity, wellbore trajectory, wellbore structure and gas injection string size.

9. The leakage rate quantitative evaluation system of the salt cavern hydrogen / helium storage during the gas injection and storage period according to claim 7, characterized in that: The real-time monitoring unit includes a gas flow meter, a gas thermometer and a wellhead pressure gauge arranged on the surface injection and production manifold to monitor and store the wellhead pressure, gas injection flow rate and gas injection temperature in real time.

10. The leakage rate quantitative evaluation system of the salt cavern hydrogen / helium storage during the gas injection and storage period according to claim 8, characterized in that: The data monitored and recorded by the real-time monitoring unit is transmitted to a data receiver via Bluetooth, and the data receiver transmits the measured data to the leakage rate quantitative evaluation unit for permeability quantitative evaluation.

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