Operation method and system for taking carbon dioxide as underground salt cavern gas storage / hydrogen storage cushion layer gas

Abstract

The invention provides an operation method and system for taking carbon dioxide as underground salt cavern gas storage / hydrogen storage cushion layer gas, and the method comprises the steps: firstly obtaining a shaft parameter and a cavity parameter, and calculating the physical property parameters of carbon dioxide at different temperatures and pressures through a data analysis platform; establishing a physical simulation model of the gas / hydrogen storage based on the wellbore parameters and the cavity parameters, solving the physical model according to the physical property parameters and the set boundary conditions, and determining effective salt cavity temperature and pressure data; based on the salt cavern temperature and pressure data and the natural gas / hydrogen physical property parameters, a dynamic gas injection and production quantity operation model of the gas / hydrogen storage is determined; different boundary conditions are set to simulate the gas mixing degree of cushion gas, and the injection-production boundary conditions meeting the requirements are selected as target injection-production parameters. According to the scheme, the operation state of the gas / hydrogen storage with carbon dioxide as cushion gas can be accurately modeled, the reliable dynamic gas injection and production amount is calculated in real time, the injection and production rate is optimized based on the gas mixing degree, and assistance is provided for the gas / hydrogen storage injection and production site.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage and optimization, and in particular to a calculation method and system for using carbon dioxide as a cushion gas for underground salt cavern gas storage / hydrogen reservoir. Background Art

[0002] Underground salt cavern gas / hydrogen storage has the advantages of high injection and production efficiency and less cushion gas required, so it has been vigorously developed. At the same time, salt cavern gas / hydrogen storage can also be applied to the field of carbon dioxide storage, including the use of carbon dioxide as cushion gas for underground salt cavern gas / hydrogen storage. In the field of energy storage, in order to ensure the stability of the salt cavity morphology during operation and to provide the necessary pressure for the extraction of natural gas, a part of the gas must always remain in the salt cavity. This part of the gas is called cushion gas; cushion gas is part of the gas storage volume in the underground gas storage. It is not extracted during the injection and production operation of the gas storage peak-shaving operation and is called "dead gas". The construction of cushion gas plays a very important role in the construction of the overall gas storage. In actual application, the conventional cushion gas construction idea is adopted. The cushion gas investment even reaches about 28% of the total investment in the construction of the gas storage. The cost is quite high, which is not conducive to large-scale application and sustainable development.

[0003] Based on this, using carbon dioxide as a gas storage cushion gas can save a lot of money and help support the development of carbon neutrality optimization goals; in addition, carbon dioxide has strong compressibility and can also increase the injectable and recoverable ratio of natural gas, which can improve the economic benefits of salt cavern gas storage to a certain extent. However, at present, the feasibility study of carbon dioxide as a gas storage / hydrogen reservoir cushion gas is still in the stage of feasibility study, and there are many technical defects in related research; for example, the patent document "Method of storing natural gas using CO2 as a salt cavern underground gas storage cushion gas" proposes a method of placing an air bag in the gas storage and filling the air bag with carbon dioxide as a cushion gas. Although this method solves the problem of high investment costs caused by the existing natural gas cushion gas technology to a certain extent, and the problem of increased natural gas production and reduced calorific value caused by the mixing of injected natural gas with cushion gas or residual brine in the dissolution cavity, this method is not very practical and is still in the conceptual stage. It lacks feasible technical guidance, and the manufacture and operation of air bags are difficult to achieve. Another patent document, "A New Physical Model of Carbon Dioxide as a Cushion Gas for Gas Storage Reservoirs," proposes a physical model that includes a physical model device body, an experimental box, an operating table, and a leakage detection box. It uses the idea of ​​physical experiments to explore carbon dioxide as a cushion gas. An experimental box is fixedly connected in the middle of the physical model device body. However, there are many interference factors in the experiment using the physical model, and it deviates greatly from the actual production situation.

[0004] In addition, although existing researchers have conducted theoretical calculations on the parameters of cushion gas and natural gas storage, such as the document "Simulation Study on Mixing of Cushion Gas and Working Gas in Underground Natural Gas Storage", it uses numerical simulation methods to establish a two-phase seepage model and a gas diffusion model, and uses a jump-type solution method to calculate the transient pressure distribution of each point in the reservoir, and then determines the velocity distribution according to Darcy's law, and finally solves the gas diffusion numerical model to determine the demand for cushion gas and the optimal gas storage pressure required for natural gas injection and production. However, this method does not take into account the changes in gas physical properties with pressure and temperature, and the coupling factors between multiple physical fields, and cannot provide reliable data basis for actual engineering applications, and cannot meet the requirements of actual process implementation.

[0005] It can be seen that there is an urgent need to provide a scientific and accurate method for calculating gas storage parameters to support the development of the process of using carbon dioxide as a cushion gas for underground salt cavern gas storage / hydrogen reservoirs.

[0006] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0007] To solve the above problems, the present invention provides a method for calculating carbon dioxide as a cushion gas for underground salt cavern gas storage / hydrogen storage. The present invention proposes a method for calculating the gas volume based on an integrated thermal coupling model of an underground salt cavern gas storage, which can be used to simulate the degree of gas mixing and the injectable and recoverable gas volume under different injection and production rates, and is of great significance for the early realization of carbon dioxide as a cushion gas for underground salt cavern gas storage. In a preferred embodiment, the method includes:

[0008] Data acquisition steps: obtaining related wellbore parameters based on completion data, and using sonar cavity measurement technology to obtain multi-directional cavity parameters of salt cavities;

[0009] Gas property analysis steps: use the matching data analysis platform to calculate the physical properties of carbon dioxide at different temperatures and pressures, and store the physical properties of natural gas / hydrogen;

[0010] Simulation operation steps: Establish a physical simulation model of the salt cavern gas storage based on wellbore parameters and cavity parameters, solve the physical model according to the physical properties of carbon dioxide and the set boundary conditions, and determine the effective salt cavern temperature and pressure data;

[0011] A gas storage parameter calculation step, based on the salt chamber temperature and pressure data and the corresponding natural gas / hydrogen physical property parameters, determines a dynamic gas injection and production volume calculation model of the gas storage / hydrogen reservoir;

[0012] The injection-production parameter optimization step is to simulate the mixing degree of carbon dioxide in the cushion gas by setting different boundary conditions, and adjust the injection-production boundary conditions according to the simulation results and the set mixing degree requirements as the target injection-production parameters.

[0013] Preferably, in one embodiment, in the data acquisition step, the process of acquiring multi-directional cavity parameters using sonar cavity measurement technology includes:

[0014] The relevant sonar parameters are measured using sonar cavity measurement technology, including measurement point, well depth, cross-sectional radius, cross-sectional area, depth range, segmented volume and cumulative volume;

[0015] Then, based on the analysis of relevant sonar parameters, the sonar cavity measurement data is determined, including the shape of the salt cavern, the total volume of the salt cavern, the burial depth of the top of the salt cavern and the burial depth of the bottom of the salt cavern.

[0016] Furthermore, in one embodiment, in the gas property analysis step, the set temperature and pressure data are imported into MATLAB, and MATLAB is used to calculate the real-time gas property parameters of carbon dioxide at different temperatures and pressures based on the carbon dioxide database.

[0017] In an optional embodiment, the simulation operation step includes:

[0018] The calculated physical properties of carbon dioxide are imported into the multi-physics field simulation system. Combined with one or more preset boundary conditions, the physical simulation model of the salt cavern gas / hydrogen storage is used for simulation to obtain the corresponding real-time temperature and pressure data of the gas / hydrogen storage as the effective salt cavity temperature and pressure.

[0019] Specifically, in a preferred embodiment, in the gas storage parameter calculation step, the dynamic gas injection volume calculation model of the gas storage reservoir described in the following formula is determined:

[0020] G in =G max -G r

[0021] Determine the dynamic gas volume calculation model of the gas / hydrogen storage described in the following formula:

[0022] G out =G r -G min

[0023] in, G in is the dynamic gas injection volume of the gas / hydrogen storage, G out is the dynamic gas extraction volume of the gas / hydrogen storage, G r is the real-time storage capacity of natural gas / hydrogen, P r 、T r , Z r, r are the real-time pressure, temperature, compression factor and density in the salt cavity, V is the volume of the salt cavity, M g is the relative molecular mass of natural gas / hydrogen, G max is the natural gas / hydrogen storage capacity at the maximum operating pressure and temperature of the salt chamber, G min It is the natural gas / hydrogen storage capacity at the minimum operating pressure and temperature of the salt chamber.

[0024] Furthermore, in one embodiment, in the injection and production parameter optimization step, different gas injection rate boundary conditions and gas production rate boundary conditions are set for different effective salt chamber temperatures and pressures, and the gas storage operation process is simulated using a simulation physical model to analyze the mixing of cushion gas and carbon dioxide, and to determine the gas injection rate and gas production rate that meet the process requirements.

[0025] In a preferred embodiment, in the simulation operation step, the process of importing the calculated carbon dioxide physical property parameters into the multi-physics field simulation system adopts the MATLAB call method, calling MATLAB for calculation with temperature and pressure data as labels, and returning the obtained physical property parameters to the multi-physics field simulation system.

[0026] Furthermore, in one embodiment, in the simulation operation step, the process of importing the calculated physical properties of carbon dioxide into the multi-physics field simulation system adopts a method of generating a text document of the physical properties of carbon dioxide and directly importing it into the multi-physics field simulation system.

[0027] Based on other aspects of the method described in any one or more of the above embodiments, the present invention further provides a storage medium storing program codes that can implement the method described in any one or more of the above embodiments.

[0028] On the other hand, based on the application of the method described in any one or more of the above embodiments, the present invention also provides a computing system for using carbon dioxide as a cushion gas for underground salt cavern gas storage / hydrogen reservoir, which executes the method described in any one or more of the above embodiments.

[0029] Compared with the closest prior art, the present invention also has the following beneficial effects:

[0030] The present invention provides a method and system for calculating carbon dioxide as cushion gas for underground salt cavern gas storage / hydrogen reservoir. The method first obtains related wellbore parameters and salt cavity size parameters, and uses a data analysis platform to calculate the physical property parameters of carbon dioxide at different temperatures and pressures; a physical simulation model of the salt cavern gas storage reservoir is established based on the wellbore parameters and cavity parameters, and the physical model is solved according to the physical property parameters of carbon dioxide and the set boundary conditions to determine effective salt cavity temperature and pressure data; based on the physical simulation model, the physical property parameters of carbon dioxide are considered to simulate and solve the salt cavity temperature and pressure data, which can ensure that the obtained temperature and pressure data can truly reflect the actual implementation of carbon dioxide as cushion gas for underground salt cavern gas storage / hydrogen reservoir, and provide a real and accurate data basis for the subsequent calculation model decision of gas storage / hydrogen parameters;

[0031] The mixing degree of carbon dioxide in the cushion gas is simulated by setting different boundary conditions, the injection-production boundary conditions are adjusted according to the simulation results, and the injection-production boundary conditions that meet the requirements are selected as the target injection-production parameters; the embodiment of the present invention takes into account the different mixing degrees of natural gas / hydrogen and carbon dioxide under different injection-production conditions, and comprehensively simulates the mixing degree of carbon dioxide in the cushion gas, so that the mixing degree of the gas under the injection-production conditions is within an acceptable range, and high-quality operation injection-production parameters are selected, which has a positive and important guiding significance for the stable operation of underground gas storage reservoirs using carbon dioxide as cushion gas.

[0032] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 Schematic diagram of the structure of an underground salt cavern gas / hydrogen storage facility according to an embodiment of the present invention;

[0035] Figure 2 It is a flow chart of a calculation method for using carbon dioxide as a gas storage / hydrogen reservoir cushion gas in an underground salt cavern provided by an embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the implementation principle of the calculation method of using carbon dioxide as underground salt cavern gas storage / hydrogen reservoir cushion gas provided in an embodiment of the present invention;

[0037] Figure 4It is a schematic diagram of the structure of a computing system for using carbon dioxide as a cushion gas for underground salt cavern gas storage / hydrogen reservoir provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The following will describe the implementation methods of the present invention in detail in conjunction with the accompanying drawings and embodiments, so that the implementers of the present invention can fully understand how the present invention applies technical means to solve technical problems and achieve the implementation process of technical effects and implement the present invention specifically according to the above implementation process. It should be noted that as long as there is no conflict, the various embodiments and various features of the embodiments in the present invention can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0039] Although the flowcharts describe the operations as sequential processes, many of the operations may be performed in parallel, concurrently, or simultaneously. The order of the operations may be rearranged. A process may be terminated when its operations are completed, but may also have additional steps not included in the accompanying drawings. A process may correspond to a method, function, procedure, subroutine, subprogram, etc.

[0040] Computer devices include user devices and network devices. Among them, user devices or clients include but are not limited to computers, smart phones, PDAs, etc.; network devices include but are not limited to a single network server, a server group consisting of multiple network servers, or a cloud composed of a large number of computers or network servers based on cloud computing. Computer devices can be operated alone to implement the present invention, or they can be connected to the network and implement the present invention through interactive operations with other computer devices in the network. The network where the computer device is located includes but is not limited to the Internet, wide area network, metropolitan area network, local area network, VPN network, etc.

[0041] The terms "first", "second", etc. may be used herein to describe various units, but these units should not be limited by these terms, and these terms are used only to distinguish one unit from another unit. The term "and / or" used herein includes any and all combinations of one or more of the listed associated items. When a unit is referred to as being "connected" or "coupled" to another unit, it can be directly connected or coupled to the other unit, or there can be intermediate units.

[0042] The terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "one", "one" and "item" used herein are also intended to include plural numbers. It should also be understood that the terms "include" and / or "comprise" used herein specify the existence of stated features, integers, steps, operations, units and / or components, without excluding the existence or addition of one or more other features, integers, steps, operations, units, components and / or combinations thereof.

[0043] In the field of energy storage, in order to ensure the stability of the salt cavity morphology during operation and to provide the necessary pressure for the extraction of natural gas / hydrogen, a portion of gas must always remain in the salt cavity, which is called cushion gas; cushion gas is part of the gas storage volume in underground gas / hydrogen storage, which is not extracted during the injection and production operation of the gas storage peak load operation, and is called "dead gas". The construction of cushion gas plays a very important role in the construction of the overall gas storage. In actual application, the conventional cushion gas construction idea is adopted, and the cushion gas investment even reaches about 28% of the total investment in the construction of the gas storage, which is quite costly and not conducive to large-scale application and sustainable development.

[0044] Carbon dioxide is the most important greenhouse gas. Using carbon dioxide as cushion gas in salt cavern gas storage can reduce the carbon dioxide content in the air, give full play to the role of underground gas storage in the energy field, and support the early realization of carbon neutrality optimization goals. In addition, carbon dioxide has strong compressibility and can also increase the injectable and recoverable proportion of natural gas, thereby improving the economic benefits of salt cavern gas storage to a certain extent.

[0045] However, the feasibility study of using carbon dioxide as a gas storage cushion gas is still in the process, and there are many technical defects in the related research. For example, the patent document "Method for storing natural gas using CO2 as a cushion gas for underground gas storage in salt caverns" proposes a method of placing a gas bag in the gas storage and filling the gas bag with carbon dioxide as a cushion gas. Although this method solves the problem of high investment cost caused by the existing natural gas cushion gas technology to a certain extent, and the problem of increased natural gas production and reduced calorific value caused by the mixing of injected natural gas with cushion gas or residual brine in the dissolution cavity, this method is not very practical and is still in the conceptual stage. There is a lack of feasible technical guidance, and the manufacture and operation of the gas bag is difficult to achieve. Another patent document "A new physical model of carbon dioxide as a gas storage cushion gas" proposes a physical model including a physical model device body, an experimental box, an operating table and a leak detection box. The idea of ​​physical experiment is used to explore carbon dioxide as a cushion gas. The middle of the physical model device body is fixedly connected with an experimental box, but there are many interference factors in the experiment using the physical model, which deviates greatly from the actual production situation.

[0046] In addition, although existing researchers have conducted theoretical calculations on the parameters of cushion gas and natural gas storage, such as the document "Simulation Study on Mixing of Cushion Gas and Working Gas in Underground Natural Gas Storage", it uses numerical simulation methods to establish a two-phase seepage model and a gas diffusion model, and uses a jump-type solution method to calculate the transient pressure distribution of each point in the reservoir, and then determines the velocity distribution according to Darcy's law, and finally solves the gas diffusion numerical model to determine the demand for cushion gas and the optimal gas storage pressure required for natural gas injection and production. However, this method does not take into account the changes in gas physical properties with pressure and temperature, and the coupling factors between multiple physical fields, and cannot provide reliable data basis for actual engineering applications, and cannot meet the requirements of actual process implementation.

[0047] The researchers of the present invention have considered that the main problems faced by carbon dioxide as a cushion gas are the gas mixing problem, the injectable and recoverable gas volume of natural gas / hydrogen, and the injection and production rate. Too fast an injection and production rate will lead to an increase in the degree of gas mixing. In order to overcome these problems and overcome the above-mentioned shortcomings, the present invention provides a calculation method and system for carbon dioxide as a cushion gas for underground salt cavern gas storage / hydrogen storage.

[0048] A gas volume calculation method based on an integrated thermal coupling model of underground salt cavern gas storage / hydrogen reservoir was proposed. Based on the commonly used parameters in the construction and operation of salt cavern gas storage, the software was used to simulate the real-time parameters in the salt cavity, and the degree of mixing of carbon dioxide under different injection and production conditions was simulated. The injectable gas volume and recoverable gas volume in the gas storage / hydrogen reservoir were calculated in combination with the carbon dioxide database, which can be used to simulate the degree of mixing and injectable gas volume under different injection and production rates. This solves the problem of carbon dioxide being used as a cushion gas for underground salt cavern gas storage / hydrogen reservoirs, and provides a basis for the implementation and configuration of carbon dioxide as a cushion gas for salt cavern gas storage / hydrogen reservoirs, which is of great significance for the early realization of carbon dioxide as a cushion gas for underground salt cavern gas storage / hydrogen reservoirs. Based on this, the use of carbon dioxide as a cushion gas for gas storage / hydrogen reservoirs can save a lot of money and help support the development of carbon neutrality optimization goals.

[0049] Next, the detailed process of the method of the embodiment of the present invention is described in detail based on the accompanying drawings. The steps shown in the flowchart of the accompanying drawings can be executed in a computer system including a set of computer executable instructions. Although the logical order of each step is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0050] Embodiment 1:

[0051] Underground salt cavern gas storage / hydrogen storage includes ground gas injection and production facilities, wellbore and cavity. Figure 1 As shown; the upper space in the cavity is used to store natural gas / hydrogen, and the lower space is used to store carbon dioxide as cushion gas. The bottom carbon dioxide maintains the pressure in the salt cavity during the gas production process to produce as much natural gas as possible.

[0052] Figure 2 The flowchart of the calculation method of using carbon dioxide as the gas storage / hydrogen reservoir cushion gas in the underground salt cavern provided by the first embodiment of the present invention is shown. Figure 2 It can be seen that the method includes the following steps.

[0053] Data acquisition steps: obtaining related wellbore parameters based on completion data, and using sonar cavity measurement technology to obtain multi-directional cavity parameters of salt cavities;

[0054] Gas property analysis steps: use the matching data analysis platform to calculate the physical properties of carbon dioxide at different temperatures and pressures, and store the physical properties of natural gas;

[0055] The simulation operation step is to establish a physical simulation model of the salt cavern gas storage based on the wellbore parameters and the cavity parameters, solve the physical model according to the physical properties of carbon dioxide and the set boundary conditions, and determine the effective salt cavern temperature and pressure data; wherein the boundary conditions preferably use the gas storage / hydrogen operation injection rate and gas production rate data;

[0056] A gas storage parameter calculation step, based on the salt chamber temperature and pressure data and the corresponding natural gas / hydrogen physical property parameters, determines a dynamic gas injection and production volume calculation model of the gas storage / hydrogen reservoir;

[0057] The injection-production parameter optimization step is to simulate the mixing degree of carbon dioxide in the cushion gas by setting different boundary conditions, and adjust the injection-production boundary conditions according to the simulation results and the set mixing degree requirements as the target injection-production parameters.

[0058] The depth of the salt cavern gas / hydrogen storage is relatively deep, and the temperature and pressure in the cavern will cause the carbon dioxide to be in a supercritical state. The density and viscosity of carbon dioxide in the supercritical state are much greater than those of natural gas / hydrogen, but different degrees of gas mixing will also be produced during the gas injection and production stage. The above embodiment of the present invention provides a strategy for simulating the degree of gas mixing in the cavern under different injection and production rates, and adjusting the injection and production rate according to the simulation results.

[0059] Figure 3 The schematic diagram of the implementation principle of the calculation decision method of using carbon dioxide as underground salt cavern gas storage / hydrogen reservoir cushion gas in the embodiment of the present invention is shown as follows: Figure 3 As shown, preferably, in one embodiment, in the data acquisition step, related wellbore parameters are obtained according to the completion design plan data, including: the outer diameter of the completion string, the wall thickness of the completion string, the inner diameter of the completion string, the bottom depth of the completion string, the outer diameter of the injection and production gas string, the wall thickness of the injection and production gas string, the inner diameter and the bottom depth of the injection and production gas string.

[0060] In actual application, the wellbore parameters, cavity parameters and gas storage / hydrogen storage operation parameters are obtained according to the following method, wherein the gas storage / hydrogen storage operation parameters are used as model boundary conditions.

[0061] According to the completion design plan, the outer diameter of the completion string, the wall thickness of the completion string, the inner diameter of the completion string, the bottom depth of the completion string, the outer diameter of the injection and production gas string, the wall thickness of the injection and production gas string, the inner diameter and the bottom depth of the injection and production gas string are obtained;

[0062] The shape, total volume, top depth and bottom depth of salt caverns are obtained by using sonar cavity data. The sonar data include measuring point, well depth, cross-sectional radius, cross-sectional area, depth range, segmented volume and cumulative volume.

[0063] In a preferred embodiment, in the data acquisition step, the process of acquiring multi-directional cavity parameters using sonar cavity measurement technology includes:

[0064] The relevant sonar parameters are measured using sonar cavity measurement technology, including measurement point, well depth, cross-sectional radius, cross-sectional area, depth range, segmented volume and cumulative volume;

[0065] Then, based on the analysis of relevant sonar parameters, the sonar cavity measurement data is determined, including the shape of the salt cavern, the total volume of the salt cavern, the burial depth of the top of the salt cavern and the burial depth of the bottom of the salt cavern.

[0066] Furthermore, the physical property parameters of carbon dioxide at different temperatures and pressures are calculated through the gas physical property analysis step using a matching data analysis platform, and the physical property parameters of natural gas / hydrogen are integrated and stored.

[0067] In an optional embodiment, in the gas physical property analysis step, the set temperature and pressure data are imported into MATLAB, and MATLAB is used to calculate the real-time physical property parameters of carbon dioxide at different temperatures and pressures based on the carbon dioxide database; including: density, viscosity, thermal conductivity, constant-pressure heat capacity, and constant-volume heat capacity of carbon dioxide at different temperatures and pressures.

[0068] In actual application, the physical properties of carbon dioxide at specified temperature and pressure are calculated based on the carbon dioxide database:

[0069] The specified temperature and pressure are imported into MATLAB, and the real-time physical properties of the gas are calculated in MATLAB based on the carbon dioxide database. The density D, thermal conductivity L, constant pressure heat capacity C, viscosity V, and constant volume heat capacity O of natural gas / hydrogen at different temperatures and pressures are:

[0070] D(i,j)=py.COOLPROP.COOLPROP.PropsSI('D','T',T(i),'P',P(j),'CO2')

[0071] L(i,j)=py.COOLPROP.COOLPROP.PropsSI('L','T',T(i),'P',P(j),'CO2')

[0072] C(i,j)=py.COOLPROP.COOLPROP.PropsSI('C','T',T(i),'P',P(j),'CO2')

[0073] V(i,j)=py.COOLPROP.COOLPROP.PropsSI('V','T',T(i),'P',P(j),'CO2')

[0074] O(i,j)=py.COOLPROP.COOLPROP.PropsSI('O','T',T(i),'P',P(j),'CO2').

[0075] Wherein, T represents temperature, P represents pressure, i represents the i-th count in the temperature cycle, j represents the j-th count in the pressure cycle, and CO2 represents carbon dioxide.

[0076] Furthermore, a simulation operation step can be performed to establish a physical simulation model of the salt cavern gas / hydrogen storage based on the wellbore parameters and cavity parameters, and the physical model can be solved according to the physical properties of carbon dioxide and the set boundary conditions to determine the effective salt cavern temperature and pressure data.

[0077] In a preferred embodiment, in the simulation operation step, a physical simulation model of a salt cavern gas storage / hydrogen storage is established using a multi-physics field simulation system, including:

[0078] The calculated physical properties of carbon dioxide are imported into the multi-physics field simulation system COMSOL. Combined with one or more preset boundary conditions, the physical simulation model of the salt cavern gas storage is used for simulation to obtain the corresponding real-time temperature and pressure data of the gas storage / hydrogen storage as the effective salt cavity temperature and pressure.

[0079] There are two ways to import the calculated carbon dioxide physical properties into the multi-physics simulation system COMSOL. The first is to use COMSOL WITH MATLAB. When COMSOL needs physical properties at a certain temperature and pressure, MATLAB is called to calculate and the physical properties are returned to COMSOL. The second is to generate a text document with the physical properties of carbon dioxide and import it into COMSOL.

[0080] Next, the gas storage parameter calculation step is used to determine the dynamic gas injection and production volume calculation model of the gas storage based on the salt chamber temperature and pressure data and the corresponding natural gas / hydrogen physical property parameters.

[0081] According to the temperature and pressure in the salt chamber and the physical parameters under the pressure and temperature state, the real gas state equation is introduced:

[0082] PV=nZRT (1)

[0083] Among them, P represents gas pressure, V represents gas volume, n represents gas molar mass, R represents gas constant, T represents gas temperature, and Z represents gas compressibility factor.

[0084] The amount of natural gas / hydrogen in this state can be calculated. Further deformation of the real gas state yields:

[0085]

[0086] make Substituting into the above formula, we can get:

[0087]

[0088] In the formula, G r is the real-time storage capacity of natural gas / hydrogen, P r 、T r , Z r , r is the real-time pressure, temperature, compression factor and density in the salt cavity, V is the volume of the salt cavity, M g is the relative molecular mass of natural gas / hydrogen; in actual calculation, the dynamic salt cavity pressures Pr and Tr are obtained in advance by simulating the injection and production rate boundary, and then brought into the formula for calculation, so that the corresponding calculation results can be obtained based on the real influencing factors of the injection and production rate boundary.

[0089] According to the maximum operating pressure and maximum operating temperature of the salt chamber, the following can be obtained by substituting the gas real state equation into it:

[0090]

[0091] According to the minimum operating pressure and minimum operating temperature of the salt chamber, we can get:

[0092]

[0093] The volume of the salt cavity that can be injected or produced is calculated based on the data obtained from S5 and S6. When injecting gas, the volume of gas that can be injected into the salt cavity is

[0094] G in =G max -G r (6)

[0095] The recoverable gas volume is

[0096] G out =G r -G min (7)

[0097] in, G in is the dynamic gas injection volume of the gas / hydrogen storage, G out is the dynamic gas extraction volume of the gas / hydrogen storage, G r is the real-time storage capacity of natural gas / hydrogen, P r 、T r , Z r , r are the real-time pressure, temperature, compression factor and density in the salt cavity, V is the volume of the salt cavity, M g is the relative molecular mass of natural gas / hydrogen, G max is the natural gas / hydrogen storage capacity at the maximum operating pressure and temperature of the salt chamber, G min It is the natural gas / hydrogen storage capacity at the minimum operating pressure and temperature of the salt chamber.

[0098] Under different injection and production conditions, the temperature and pressure changes and gas speed in the cavity are different, so the degree of mixing of natural gas / hydrogen and carbon dioxide is different. Too fast an injection and production rate will lead to an increase in the degree of mixing. Too fast a change in temperature and pressure in the cavity will also affect the physical properties of carbon dioxide and the degree of mixing.

[0099] The degree of turbulence of carbon dioxide in the cushion gas is simulated by setting different boundary conditions, and the injection-production boundary conditions are adjusted according to the simulation results so that the degree of gas mixing under the injection-production conditions is within an acceptable range.

[0100] Furthermore, preferably, in one embodiment, the degree of mixing of different gases is expressed by gas concentration. Therefore, the injection-production parameter optimization step is performed, and the degree of mixing of cushion gas carbon dioxide is simulated by setting different gas concentration boundary conditions. The injection-production boundary conditions are adjusted according to the simulation results and the set mixing degree requirements as the target injection-production parameters.

[0101] In a preferred embodiment, in the injection and production parameter optimization step, different gas injection rate boundary conditions and gas production rate boundary conditions are set for different effective salt chamber temperatures and pressures, and a simulation physical model is used to simulate the gas storage operation process, analyze the mixing of cushion gas and carbon dioxide, and decide on the gas injection rate and gas production rate that meet the process requirements.

[0102] In an optional embodiment, the degree of gas mixing of the simulation results can be compared with the set conditions. If the requirements are not met, the injection-production boundary parameters are adjusted to re-simulate the degree of gas mixing of the cushion gas carbon dioxide until the simulated gas mixing degree meets the set requirements. The injection-production boundary parameters corresponding to different temperature and pressure data are associated and recorded as a gas storage / hydrogen storage injection-production parameter configuration list to provide implementation assistance for actual gas storage operations using carbon dioxide as cushion gas for underground gas storage / hydrogen storage.

[0103] The embodiments of the present invention can be used for operation guidance of underground gas storage / hydrogen storage using carbon dioxide as cushion gas, can accurately model the operation status of gas storage / hydrogen storage using carbon dioxide as cushion gas, can calculate in real time the injectable gas volume and the degree of mixing of the carbon dioxide cushion gas at different injection and production rates, and can be used for on-site injection and production of gas / hydrogen storage.

[0104] The method of the present invention can simulate the mixing degree of cushion gas in salt cavern gas storage / hydrogen storage under different gas injection or gas production rates, the changing law of temperature and pressure in gas storage / hydrogen storage during gas injection and production, and combine it with the carbon dioxide database to calculate the dynamic gas storage capacity. In addition to fluid analysis, solid mechanics analysis can be further performed based on the simulation results of gas flow and temperature change, and mechanical analysis of the surrounding rock of the gas storage reservoir, especially the casing shoe part, to ensure the stability of the gas storage / hydrogen storage during the injection and production process. The calculation steps are clear and can meet the actual engineering needs.

[0105] Taking a salt cavern gas storage as an example, the cavity volume is 260,000 m 3 , working temperature is 47℃, working pressure is 6MPa-17MPa, and the compression factors of carbon dioxide and natural gas at different temperatures and pressures calculated in MATLAB are shown in the following table.

[0106]

[0107] If carbon dioxide is used as cushion gas, when the lower limit working pressure is 6MPa, the volume of carbon dioxide in the gas storage under ground standard conditions is:

[0108]

[0109] If natural gas is used as cushion gas, when the lower limit working pressure is 6MPa, the volume of natural gas in the gas storage under ground standard conditions is:

[0110]

[0111] When the upper working pressure is 17MPa, the volume of carbon dioxide cushion gas in the salt cavity of the gas storage is:

[0112]

[0113] When the upper limit working pressure is 17MPa, the volume of natural gas in the salt cavity of the gas storage is:

[0114] V = 26 × 10 4 -4.74×10 4 =21.26×10 4 m 3 (11)

[0115] If carbon dioxide is used as cushion gas, when the upper limit of working pressure is 17MPa, the volume of natural gas / hydrogen in the gas storage under standard conditions is:

[0116]

[0117] If natural gas is used as cushion gas, when the upper limit of working pressure is 17MPa, the volume of natural gas in the gas storage under ground standard conditions is:

[0118]

[0119] If carbon dioxide is used as cushion gas, the working gas volume or gas production volume of the gas storage is:

[0120]

[0121] If natural gas is used as cushion gas, the working gas volume or gas production volume of the gas storage is:

[0122]

[0123] It can be seen from this that under the same gas storage conditions, using carbon dioxide as cushion gas can increase the amount of gas injected and produced.

[0124] For the above-mentioned method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0125] It should be pointed out that in other embodiments of the present invention, the method can also obtain a new operation and decision method for using carbon dioxide as a cushion gas for underground salt cavern gas storage / hydrogen storage by combining one or several of the above-mentioned embodiments, so as to achieve accurate optimization and development support for the process of using carbon dioxide as a cushion gas for underground salt cavern gas storage.

[0126] It should be noted that, based on the method in any one or more of the above-mentioned embodiments of the present invention, the present invention also provides a storage medium, on which is stored a program code that can implement the method as described in any one or more of the above-mentioned embodiments, and when the code is executed by the operating system, it can implement the above-mentioned operation method of using carbon dioxide as a cushion gas for underground salt cavern gas storage / hydrogen storage.

[0127] Embodiment 2:

[0128] The method is described in detail in the embodiments disclosed in the present invention. The method of the present invention can be implemented by various forms of devices or systems. Therefore, based on other aspects of the method described in any one or more embodiments, the present invention also provides a computing system for using carbon dioxide as underground salt cavern gas storage / hydrogen reservoir cushion gas, which is used to execute the computing method for using carbon dioxide as underground salt cavern gas storage / hydrogen reservoir cushion gas described in any one or more embodiments. Specific embodiments are given below for detailed description.

[0129] Specifically, Figure 4 FIG. 2 shows a schematic diagram of a computing system for using carbon dioxide as a gas storage / hydrogen reservoir cushion gas in an underground salt cavern according to an embodiment of the present invention. Figure 4 As shown, the system includes:

[0130] A data acquisition module configured to acquire associated wellbore parameters based on completion data and to acquire multi-directional cavity parameters of salt cavities using sonar cavity measurement technology;

[0131] A gas physical property analysis module, which is configured to use a matching data analysis platform to calculate the physical property parameters of carbon dioxide at different temperatures and pressures, and store the physical property parameters of natural gas / hydrogen;

[0132] A simulation operation module is configured to establish a physical simulation model of the salt cavern gas storage based on wellbore parameters and cavity parameters, solve the physical model according to the physical properties of carbon dioxide and the set boundary conditions, and determine effective salt cavern temperature and pressure data;

[0133] A gas storage parameter calculation module, configured to determine a dynamic gas injection and production volume calculation model of a gas storage / hydrogen reservoir based on the salt chamber temperature and pressure data and corresponding natural gas / hydrogen physical property parameters;

[0134] The injection and production parameter optimization module is configured to simulate the mixing degree of the cushion gas carbon dioxide by setting different boundary conditions, and adjust the injection and production boundary conditions according to the simulation results and the set mixing degree requirements as the target injection and production parameters.

[0135] Preferably, in one embodiment, the data acquisition module is configured to use sonar cavity measurement technology to measure relevant sonar parameters as multi-directional cavity parameters, including measuring point, well depth, cross-sectional radius, cross-sectional area, depth range, segmented volume and cumulative volume.

[0136] Then, based on the analysis of relevant sonar parameters, the sonar cavity measurement data is determined, including the shape of the salt cavern, the total volume of the salt cavern, the burial depth of the top of the salt cavern and the burial depth of the bottom of the salt cavern.

[0137] Furthermore, in one embodiment, the gas physical property analysis module is configured to: import the set temperature and pressure data into MATLAB, and use MATLAB to calculate the real-time physical property parameters of carbon dioxide at different temperatures and pressures based on the carbon dioxide database.

[0138] Optionally, in one embodiment, the simulation operation module is configured to perform the following operations:

[0139] The calculated physical properties of carbon dioxide are imported into the multi-physics field simulation system. Combined with one or more preset boundary conditions, the physical simulation model of the salt cavern gas / hydrogen storage is used for simulation to obtain the corresponding real-time temperature and pressure data of the gas / hydrogen storage as the effective salt cavity temperature and pressure.

[0140] Further, in an optional embodiment, the gas storage parameter calculation module determines the dynamic gas injection volume calculation model of the gas storage according to the following formula:

[0141] G in =G max -G r

[0142] Determine the dynamic gas volume calculation model of the gas / hydrogen storage described in the following formula:

[0143] G out =G r -G min

[0144] in, G in is the dynamic gas injection volume of the gas / hydrogen storage, G out is the dynamic gas extraction volume of the gas / hydrogen storage, G r is the real-time storage capacity of natural gas / hydrogen, P r 、T r , Z r , r are the real-time pressure, temperature, compression factor and density in the salt cavity, V is the volume of the salt cavity, M g is the relative molecular mass of natural gas / hydrogen, G max is the natural gas / hydrogen storage capacity at the maximum operating pressure and temperature of the salt chamber, G min It is the natural gas / hydrogen storage capacity at the minimum operating pressure and temperature of the salt chamber.

[0145] In a preferred embodiment, the injection and production parameter optimization module is configured as follows: different gas injection rate boundary conditions and gas production rate boundary conditions are set for different effective salt chamber temperatures and pressures, the gas storage operation process is simulated using a simulation physical model, the mixing of cushion gas and carbon dioxide is analyzed, and the injection rate and gas production rate that meet the process requirements are determined.

[0146] Furthermore, in an optional embodiment, the simulation operation module is specifically configured to import the calculated physical properties of carbon dioxide into the multi-physics field simulation system by using MATLAB calling method, calling MATLAB for calculation with temperature and pressure data as labels, and returning the obtained physical properties to the multi-physics field simulation system.

[0147] Specifically, in a preferred embodiment, the simulation operation module is configured to import the calculated physical properties of carbon dioxide into the multi-physics field simulation system by generating a text document from the physical properties of carbon dioxide and directly importing it into the multi-physics field simulation system.

[0148] In the computing system for using carbon dioxide as cushion gas for underground salt cavern gas storage / hydrogen storage provided by the embodiment of the present invention, each module or unit structure can operate independently or in combination according to actual data setting requirements and simulation computing requirements to achieve corresponding technical effects.

[0149] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0150] The "one embodiment" mentioned in the specification means that a particular feature, structure or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. Therefore, the phrase "one embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0151] Although the embodiments disclosed in the present invention are as above, the above contents are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A calculation method for using carbon dioxide as a gas cushion for underground salt cavern gas storage / hydrogen storage, characterized in that: The method comprises: Data acquisition steps: obtaining related wellbore parameters based on completion data, and using sonar cavity measurement technology to obtain multi-directional cavity parameters of salt cavities; Gas property analysis steps: use the matching data analysis platform to calculate the physical properties of carbon dioxide at different temperatures and pressures, and store the physical properties of natural gas / hydrogen; Simulation operation steps: Establish a physical simulation model of the salt cavern gas storage based on wellbore parameters and cavity parameters, solve the physical model according to the physical properties of carbon dioxide and the set boundary conditions, and determine the effective salt cavern temperature and pressure data; A gas storage parameter calculation step, based on the salt chamber temperature and pressure data and the corresponding natural gas / hydrogen physical property parameters, determines a dynamic gas injection and production volume calculation model of the gas storage / hydrogen reservoir; The injection-production parameter optimization step is to simulate the mixing degree of carbon dioxide in the cushion gas by setting different boundary conditions, and adjust the injection-production boundary conditions according to the simulation results and the set mixing degree requirements as the target injection-production parameters.

2. The method according to claim 1, characterized in that In the data acquisition step, the process of obtaining multi-directional cavity parameters using sonar cavity measurement technology includes: The relevant sonar parameters are measured using sonar cavity measurement technology, including measurement point, well depth, cross-sectional radius, cross-sectional area, depth range, segmented volume and cumulative volume; Then, based on the analysis of relevant sonar parameters, the sonar cavity measurement data is determined, including the shape of the salt cavern, the total volume of the salt cavern, the burial depth of the top of the salt cavern and the burial depth of the bottom of the salt cavern.

3. The method according to claim 1, characterized in that In the gas property analysis step, the set temperature and pressure data are imported into MATLAB, and MATLAB is used to calculate the real-time gas property parameters of carbon dioxide at different temperatures and pressures based on the carbon dioxide database.

4. The method according to claim 1, characterized in that: The simulation operation steps include: The calculated physical properties of carbon dioxide are imported into the multi-physics field simulation system. Combined with one or more preset boundary conditions, the physical simulation model of the salt cavern gas / hydrogen storage is used for simulation to obtain the corresponding real-time temperature and pressure data of the gas / hydrogen storage as the effective salt cavity temperature and pressure.

5. The method according to claim 1, characterized in that In the gas storage parameter calculation step, the dynamic gas injection volume calculation model of the gas storage reservoir described in the following formula is determined: G in =G max -G r Determine the dynamic gas volume calculation model of the gas / hydrogen storage described in the following formula: G out =G r -G min in, G in is the dynamic gas injection volume of the gas / hydrogen storage, G out is the dynamic gas extraction volume of the gas / hydrogen storage, G r is the real-time storage capacity of natural gas / hydrogen, P r , T r , Z r , r are the real-time pressure, temperature, compression factor and density in the salt cavity, V is the volume of the salt cavity, M g is the relative molecular mass of natural gas / hydrogen, G max is the natural gas / hydrogen storage capacity at the maximum operating pressure and temperature of the salt chamber, G min It is the natural gas / hydrogen storage capacity at the minimum operating pressure and temperature of the salt chamber.

6. The method according to claim 1, characterized in that In the injection and production parameter optimization step, different gas injection rate boundary conditions and gas production rate boundary conditions are set according to different effective salt cavity temperatures and pressures. The gas storage operation process is simulated using a simulation physical model, the mixing of cushion gas and carbon dioxide is analyzed, and the gas injection rate and gas production rate that meet the process requirements are determined.

7. The method according to claim 1, characterized in that In the simulation operation step, the process of importing the calculated carbon dioxide physical properties into the multi-physics field simulation system adopts the MATLAB call method, calling MATLAB for calculation with temperature and pressure data as labels, and returning the obtained physical properties to the multi-physics field simulation system.

8. The method according to claim 1, characterized in that In the simulation operation step, the process of importing the calculated physical property parameters of carbon dioxide into the multi-physics field simulation system adopts a method of generating a text document of the physical property parameters of carbon dioxide and directly importing it into the multi-physics field simulation system.

9. A storage medium, characterized in that: The storage medium stores program codes that can implement the method as claimed in any one of claims 1 to 8.

10. A computing system for using carbon dioxide as a gas storage / hydrogen reservoir cushion gas in underground salt caverns, characterized in that: The system executes the method according to any one of claims 1 to 9.

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