Method for measuring reserve and volume of underground salt cavern gas storage through gas detection

Abstract

The invention discloses a method for measuring reserve and volume of an underground salt cavern gas storage through gas detection, and a single detection method comprises the following steps: S11, obtaining a cavity volume approximate value, temperature and pressure data of a target salt cavern, and selecting detection gases with similar molar masses according to working gas types; s12, on the basis of the required reserve precision and the detection gas precision, the detection gas injection amount is calculated; s13, injecting detection gas in the gas injection process, collecting the gas during gas production, and detecting the concentration of the gas; s14, calculating the amount and mass of substances of the working gas according to the concentration of the detected gas; s15, calculating the volume of the gas storage in combination with a gas state equation; based on gas concentration diffusion, the amount of the working gas substance is obtained by measuring the detection gas concentration, the cavity volume is obtained according to the pressure and temperature data, the amount and the volume of the gas stored in the cavity can be detected with low cost, no influence on gas storage operation and variable precision, and single detection and continuous detection can be carried out.

Description

Technical Field

[0001] This application relates to the field of underground energy storage engineering technology, and in particular to a method for measuring the storage capacity and volume of underground salt cavern gas storage facilities by gas detection. Background Technology

[0002] Salt cavern gas storage facilities are underground caverns formed by injecting fresh water or low-saturation brine into thick underground salt layers or salt domes using water-dissolving extraction methods, dissolving the salt layer, and then draining the saturated or near-saturated brine. Salt cavern gas storage facilities are excellent carriers for the storage of compressed air and natural gas, and can be used for the construction of natural gas storage facilities such as the Jianghan Gas Storage Facility, and compressed air storage facilities such as the Feicheng Compressed Air Energy Storage Power Station in Shandong Province.

[0003] Currently, the volume measurement of underground salt cavern gas storage facilities mainly relies on two methods: (1) Sonar cavity measurement method: It requires shutdown to set up equipment, which is costly, time-consuming (≥2 weeks), and data processing is complicated. When the cavity shape is complex, sonar cannot make accurate measurements, and the error of complex cavities can reach 5%-10%. (2) Brine discharge method: It is only applicable during the cavity construction period and cannot be implemented during the operation period. Furthermore, ignoring sediment will result in an artificially inflated volume of 3%-8%.

[0004] None of the above methods can achieve real-time monitoring of the operating volume without interrupting production or interfering with the injection-production cycle, resulting in large deviations in the calculation of gas storage volume (such as peak-shaving errors exceeding 15% in compressed air energy storage power stations). Summary of the Invention

[0005] To address the aforementioned problems, this application provides a method for measuring the storage capacity and volume of underground salt cavern gas storage facilities using gas detection. This method is low-cost, does not affect gas storage operations, and allows for variable-precision detection of the gas storage volume and volume within the detection chamber. It can perform single or continuous detection. The technical solution is as follows: This application provides a method for measuring the storage capacity and volume of an underground salt cavern gas storage facility using gas detection, including a single-detection method. The single-detection method includes the following steps: S11 Obtaining approximate cavity volume, temperature, and pressure data of the target salt cavern, and selecting a detection gas with a similar molar mass based on the type of working gas; S12 Calculating the injection volume of the detection gas based on the required storage accuracy and detection gas accuracy; S13 Injecting the detection gas during the injection process, collecting the gas during gas sampling, and detecting its concentration; S14 Calculating the amount of substance and mass of the working gas based on the detection gas concentration; S15 Calculating the gas storage capacity using the gas state equation.

[0006] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage facility by gas detection, a continuous detection method is further included. The continuous detection method includes the following steps: S21 performing the single detection method; S22 calculating the amount of substance of the remaining detection gas after gas extraction; S23 determining the amount of supplementary detection gas according to the accuracy requirements; S24 supplementing and injecting detection gas and detecting the concentration change; S25 calculating the working gas parameters based on the concentration change; and S26 updating the gas storage facility volume data.

[0007] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage tank by gas detection, the molar mass difference between the detection gas and the working gas is ≤5 g / mol, and when the working gas is compressed air, the detection gas is ethane.

[0008] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage tank by gas detection, the gas injection rate is satisfied that the mixing concentration is less than 10% of the explosion limit, and the gas is injected uniformly throughout the injection process.

[0009] For example, in one embodiment of the method for measuring the reserves and volume of an underground salt cavern gas storage facility by gas detection, the gas collection period is the pipeline gas in the middle pressure range of the gas extraction stage.

[0010] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage tank by gas detection, in step S22, the amount of the remaining detected gas substance is calculated by the following formula: in, This represents the amount of substance remaining in the detected gas. To detect gas concentration, This is the low-pressure operating pressure of the gas storage facility after gas extraction is completed. This refers to the cavity volume during low-pressure operation. The gas constant is This refers to the temperature of the gas storage tank.

[0011] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage tank by gas detection, in step S23, the amount of gas to be supplemented for detection satisfies the following formula: or in, To supplement the detection of the amount of gaseous substances, This refers to the amount of detection gas injected during a single test.

[0012] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage facility by gas detection, the gas concentration detection employs a gas chromatography-flame ionization detector with a detection accuracy of ≤0.01ppm.

[0013] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage facility using gas detection, the formula for calculating the storage capacity is: in, For the gas storage capacity, The amount of the working gas substance. The gas constant is For the temperature of the gas storage facility, This refers to the pressure in the gas storage facility.

[0014] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage facility by gas detection, the replenishment cycle in the continuous detection method satisfies the following: Otherwise, a new round of single-detection initialization is triggered; where, is the high-pressure operating pressure of the gas storage tank at the start of gas extraction, and n is the number of interval cycles.

[0015] The beneficial effects of the method for measuring the storage capacity and volume of an underground salt cavern gas storage facility through gas detection provided in some embodiments of this application are as follows: This application is based on gas concentration diffusion, measuring the concentration of the detected gas to obtain the amount of working gas, and obtaining the cavity volume based on pressure and temperature data. The biggest advantage compared to brine and sonar cavity measurement is that it does not interrupt the gas storage facility's injection and extraction cycle; secondly, it directly measures the amount and volume of gas stored in the gas cavity, and the gas volume equals the salt cavity gas volume, eliminating the influence of brine and sediment; this application can also use the detected gas simultaneously for tracer gas measurement to detect whether the gas storage facility has experienced gas leakage. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram illustrating the principle of the method for measuring the storage capacity and volume of underground salt cavern gas storage using gas detection according to this application. Figure 2This is a flowchart of the single-detection method for measuring the storage capacity and volume of underground salt cavern gas storage using gas detection, as described in this application. Figure 3 This is a logic block diagram of the single-detection method for measuring the storage capacity and volume of underground salt cavern gas storage using gas detection, as described in this application. Figure 4 This is a flowchart of the continuous detection method for measuring the storage capacity and volume of underground salt cavern gas storage using gas detection, as described in this application. Figure 5 This is a logic block diagram of the continuous detection method for measuring the storage capacity and volume of underground salt cavern gas storage using gas detection, as described in this application. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0019] This application provides a method for measuring the storage capacity and volume of underground salt cavern gas storage facilities using gas detection. Figure 1 This is a simplified schematic diagram of the core detection method of this application. When the salt cavern 1 has a large volume and its volume cannot be directly measured, a small amount of quantitative detection gas 2 is injected. The detection gas and the working gas have similar molar molecular masses, preventing stratification and allowing them to mix uniformly through convection and diffusion to form a salt cavern 3 containing the detection gas. The detection gas 4 is then extracted, and the volume concentration of the detection gas in the extracted gas is measured. Figure 1 The formula shows that the volume of the salt cavern can be calculated from the volume concentration, the amount of gaseous substance added, and the temperature and pressure of the salt cavern.

[0020] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage facility by gas detection, a single detection method is included, such as... Figure 2-3 As shown, the single detection method includes the following steps: S11 acquires the approximate volume, temperature, and pressure data of the target salt cavern, and selects a detection gas with a similar molar mass based on the type of working gas. Specifically, the approximate volume of the cavity (of the same order of magnitude), the temperature and pressure of the cavity are obtained through the original cavity measurement data; the amount of gaseous substance stored is calculated through the gas pressure. The selected detection gas and working gas have similar molar molecular masses to ensure that the detection gas and working gas can be mixed uniformly without stratification. For example, the molar mass difference between the detection gas and the working gas is ≤5 g / mol. The working gas includes compressed air or natural gas. When the working gas is compressed air, the detection gas is ethane. S12 calculates the amount of detection gas to be injected based on the required storage accuracy and detection gas accuracy. Specifically, based on the required accuracy of the working gas storage or the salt cavern volume, combined with the detection accuracy of the detection gas and the estimated storage obtained in S11, the amount of detection gas to be added is calculated. S13 injects detection gas during the gas injection process, and collects and detects the gas concentration during gas sampling. Specifically, the amount of detection gas calculated in S12 is added during the gas injection process in the gas storage tank, and the extracted gas is collected when the gas is extracted, and the concentration of the detection gas is detected using a high-precision detection instrument. When injecting the detection gas, the injection rate must be controlled so that the concentration of the detection gas in the mixed gas is much lower than its explosion limit. For example, the injection rate of the detection gas should meet the requirement that the mixed concentration is less than 10% of the explosion limit, and the gas should be injected uniformly throughout the injection process. When collecting extracted gas, priority should be given to collecting the gas in the pressure pipeline during the middle period of the extraction stage to avoid the influence of residual gas in the pipeline and external gas contamination on the test results. S14 calculates the amount and mass of the working gas based on the concentration of the detected gas; Specifically, based on the concentration of the detected gas obtained in S13, the amount and mass of the working gas in the gas storage tank are calculated. S15 combines the temperature, pressure, and gas pressure relationships of the gas storage facility with the gas state equation to calculate the gas storage capacity. The formula for calculating the gas storage capacity is as follows: in, For the gas storage capacity, The amount of the working gas substance. The gas constant is For the temperature of the gas storage facility, This refers to the pressure in the gas storage facility.

[0021] This application discloses a single-detection method for measuring the storage capacity and volume of underground salt cavern gas storage using gas detection. The method involves acquiring preliminary measurement data of the target compressed air storage tank and calculating the amount of detection gas to be injected. During compressed air injection, vaporized ethane is mixed in and stored under pressure for a period of time. When the compressed air is extracted, a portion of the gas is collected, and the collected gas is analyzed for detection gas concentration and then its accuracy is verified. The amount of compressed air injected into the salt cavern is calculated based on the concentration. The corresponding salt cavern volume is calculated using the salt cavern temperature and pressure, and error estimation is performed.

[0022] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage facility using gas detection, such as Figure 4-5As shown, it also includes a continuous detection method, which includes the following steps: S21 executes the single detection method, that is, firstly, performs a single detection of the gas storage capacity and gas storage volume of the salt cavern gas storage tank; S22 calculates the amount of substance of the remaining detected gas after gas sampling; Specifically, the amount of residual detection gas in the gas storage tank after the working gas extraction stage is calculated using the following formula: in, This represents the amount of substance remaining in the detected gas. To detect gas concentration, This is the low-pressure operating pressure of the gas storage facility after gas extraction is completed. This refers to the cavity volume during low-pressure operation. The gas constant is This refers to the temperature of the gas storage tank.

[0023] S23 determines the amount of supplementary detection gas based on accuracy requirements; Specifically, based on the required working gas storage accuracy or salt cavern volume accuracy, combined with the detection accuracy of the detection gas and the amount of remaining detection gas, the amount of detection gas to be added is calculated. This addition amount can be zero. When the required accuracy is consistent with the previous detection accuracy, the amount of detection gas to be added satisfies the following formula: or in, To supplement the detection of the amount of gaseous substances, This refers to the amount of detection gas injected during a single test.

[0024] S24 supplements and injects detection gas and detects the change in concentration; Specifically, the amount of gas to be detected calculated in S23 is added during the gas injection process in the gas storage tank, and the extracted gas is collected when the gas is extracted, and the concentration change of the gas to be detected is detected using a high-precision detection instrument. S25 calculates working gas parameters based on concentration changes; Specifically, based on the change in the concentration of the detected gas obtained in S24, the amount of substance, mass, and amount of gas added to the gas storage tank are calculated. S26 calculates the volume of the gas storage facility by combining the temperature, pressure, and gas pressure relationship of the gas storage facility, and updates the gas storage facility volume data.

[0025] The formula for calculating the volume of a gas storage facility is: in, For the gas storage capacity, The amount of the working gas substance. The gas constant is For the temperature of the gas storage facility, This refers to the pressure in the gas storage facility.

[0026] For example, in one embodiment of the method for measuring the storage capacity and volume of an underground salt cavern gas storage facility by gas detection, the gas concentration detection employs a gas chromatography-flame ionization detector with a detection accuracy of ≤0.01ppm.

[0027] This application discloses a continuous detection method for measuring the storage capacity and volume of underground salt cavern gas storage facilities using gas detection. The method involves acquiring single-time measurement data of a target compressed air storage facility; calculating the amount of ethane in the salt cavern after the last gas extraction cycle; determining the amount of detection gas (liquid ethane) to be injected based on accuracy requirements and measurement limits; supplementing ethane when the volume is below the detection limit, and not injecting it when it is above the limit, although this reduces accuracy after each extraction and injection cycle; selectively supplementing the gas with vaporized ethane through compressed air injection; maintaining pressure and storing the gas for a period of time; collecting a portion of the gas when extracting compressed air; analyzing the concentration of the collected gas; performing accuracy verification; calculating the amount of compressed air injected into the salt cavern based on the concentration difference; and calculating the corresponding salt cavern volume based on the salt cavern temperature and pressure, and estimating the error.

[0028] Example 1 This application is applicable to a single-detection method for the quantity of gaseous substances stored in a gas storage facility and the volume of the salt cavern. Taking a compressed air energy storage salt cavern gas storage facility as an example, such as... Figure 2-3 The steps shown are as follows: Step 1: Obtain the estimated storage capacity of the target salt cavern; using existing cavity measurement data, including approximate cavity volume (of the same order of magnitude), cavity temperature and pressure; based on the construction measurement results of a salt cavern gas storage facility at a compressed air energy storage power station in Shandong; the salt cavern gas storage facility has a volume of approximately 500,000 cubic meters, a temperature of 45 degrees Celsius (318.5K), and operates at a high pressure of 15MPa after gas is injected into the storage facility.

[0029] Compressed air was used to determine the physical properties of the gas being tested. A suitable test gas was selected based on the types of working gases stored. The working gas was compressed air with a molecular molar mass of 28.97 g / mol. Ethane was chosen as the test gas, with a molecular molar mass of 30.07 g / mol. The similar molecular molar masses allow for relatively uniform diffusion into the air without stratification.

[0030] Step 2: Determine the gas injection volume based on gas detection capability and volume measurement accuracy requirements: Considering cost and detection accuracy, the detection method used is GC-FID (Gas Chromatography-Flame Ionization Detector), with a detection accuracy of 0.01 ppm and a volume accuracy requirement of 0.1%.

[0031] Based on the derivation, the following error propagation formula is obtained: The detected gas concentration meets the following requirements: Mass of ethane injected: To reduce experimental error and considering cost, liquid ethane was chosen for purchase. The purchase quantity is greater than 851.68, and for ease of purchase, 1000 kg was selected.

[0032] Calculate the amount of ethane injected: Step 3: Based on the obtained gas quantity, add the detection gas during the gas injection process in the gas storage tank, collect the extracted gas during gas extraction, and use a high-precision detection instrument to detect the gas concentration; during a certain operating cycle of the compressed air storage tank, add liquid ethane to the compressed air injection pipeline, and ensure that the mixed gas is far below the ethane explosion limit. Inject the detection gas evenly throughout the entire compressed air injection process.

[0033] After injection, during the high-pressure operation phase, ethane mixes evenly with the compressed air in the salt chamber through natural convection.

[0034] During the gas extraction phase, it is best to collect the extracted gas from the pressure pipeline during the middle period of the extraction phase to avoid air pollution caused by residual gas in the pipeline.

[0035] The concentration of ethane in the collected gas was detected using GC-FID (Gas Chromatography-Flame Ionization Detector). The result is the concentration of ethane. It meets the gas detection concentration requirements with a relative error of less than 0.1%.

[0036] Step 4: Based on the detected gas concentration, calculate the amount and mass of the working gas in the gas storage tank: Calculate the amount of the working gas in the gas storage tank according to the gas volume law. Working gas quality of the gas storage facility: Step 5: Calculate the volume of the gas storage tank by combining its temperature, pressure, and gas pressure relationship: The volume of the gas storage tank (after gas injection) can be obtained by combining the temperature and pressure of the gas storage tank with the gas pressure relationship. This gives the volume of the gas storage tank during high-pressure operation (equal to the volume of the gaseous substance). Volumetric relative error (ignoring pressure and temperature measurement errors): Example 2 This application can be applied to methods for continuous detection of the quantity of gaseous substances stored in gas storage facilities and the volume of salt caverns, such as... Figure 4-5 The steps shown are as follows: Step 1: First, measure the gas storage capacity of the single salt cavern gas storage tank: the gas storage tank volume is measured as described in Example 1.

[0037] Step Two: Calculate the amount of residual gas after the working gas extraction stage is completed: After gas extraction, the salt cavern enters low-pressure operation, and the gas pressure in the salt cavern is measured. Based on the relationship between gas partial pressure and concentration, we can obtain: in This refers to the cavity pressure during low-pressure operation. The cavity volume during low-pressure operation can be calculated based on the cavity shrinkage rate, or it can be approximated as... .

[0038] Step 3: Calculate the amount of detection gas to be added: Based on the required working gas storage accuracy or salt cavern volume accuracy, combined with the detection gas detection accuracy, the amount of residual substance in the detection gas, and the amount of residual substance in the detection gas obtained in the previous step, calculate the amount of detection gas to be added (which can be zero).

[0039] If the required accuracy is the same as the previous test, simply replenish the ethane in the chamber to the amount of the same substance for a single test.

[0040] Measurements can still be performed without replenishing the detection material, but the accuracy will gradually decrease. At this point: To improve measurement accuracy, additional gaseous substances need to be detected. The relative error is as follows: Amount of gaseous substance in the cavity: The subsequent measurement method is similar to that in Example 1, but the measured volume data and concentration data are used to update the concentration and volume of the detected gas each time.

[0041] If an interval replenishment method is used, each detection is considered a single measurement. Repeating this cycle n times can decrease the concentration, allowing for an approximate calculation of the gas concentration. This method calculates When the concentration is less than the limit required for detection accuracy, the interval period n can be regarded as the minimum number of cycles for a single measurement.

[0042] This application utilizes the fact that ethane and air have similar densities and a molecular weight of 30 g / mol, exhibiting good and uniform diffusion in compressed air and exhibiting minimal stratification. A certain amount of ethane is added when injecting compressed air into the gas storage tank, and the ethane content in the extracted air is measured. The concentration diffusion theorem is used to calculate the amount of compressed air contained in the chamber. Unlike single-stage chamber measurement techniques, this method allows for continuous monitoring of the chamber volume because the concentration changes continuously. However, due to limitations in detection technology, ethane needs to be refilled at appropriate intervals. Furthermore, an ethane gas concentration monitoring instrument can be installed at the project site for automatic detection in the event of a chamber leak.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for measuring the storage capacity and volume of an underground salt cavern gas storage facility using gas detection, characterized in that, This includes a single-detection method, which comprises the following steps: S11 acquires the approximate volume, temperature, and pressure data of the target salt cavern, and selects a detection gas with a similar molar mass based on the type of working gas. S12 calculates the amount of detection gas to be injected based on the required storage accuracy and detection gas accuracy. S13 injects detection gas during the gas injection process, and collects and detects the gas concentration during gas sampling. S14 calculates the amount and mass of the working gas based on the concentration of the detected gas; S15 calculates the gas storage tank volume using the gas state equation.

2. The method for measuring the storage capacity and volume of underground salt cavern gas storage facilities by gas detection according to claim 1, characterized in that, It also includes a continuous detection method, which includes the following steps: S21 executes the single detection method; S22 calculates the amount of substance of the remaining detected gas after gas sampling; S23 determines the amount of supplementary detection gas based on accuracy requirements; S24 supplements and injects detection gas and detects the change in concentration; S25 calculates working gas parameters based on concentration changes; S26 Updates gas storage capacity data.

3. The method for measuring the storage capacity and volume of underground salt cavern gas storage facilities by gas detection according to claim 1 or 2, characterized in that, The molar mass difference between the detection gas and the working gas is ≤5 g / mol, and when the working gas is compressed air, the detection gas is ethane.

4. The method for measuring the storage capacity and volume of underground salt cavern gas storage tanks by gas detection according to claim 1 or 2, characterized in that, The gas injection rate is tested to ensure that the mixed concentration is less than 10% of the explosion limit, and that the gas is injected uniformly throughout the injection process.

5. The method for measuring the storage capacity and volume of underground salt cavern gas storage tanks by gas detection according to claim 1 or 2, characterized in that, The gas collection period is the pipeline gas in the middle pressure range of the gas production stage.

6. The method for measuring the storage capacity and volume of underground salt cavern gas storage tanks by gas detection according to claim 2, characterized in that, In step S22, the amount of remaining detected gaseous substance is calculated using the following formula: in, This represents the amount of substance remaining in the detected gas. To detect gas concentration, This is the low-pressure operating pressure of the gas storage facility after gas extraction is completed. This refers to the cavity volume during low-pressure operation. The gas constant is This refers to the temperature of the gas storage tank.

7. The method for measuring the storage capacity and volume of underground salt cavern gas storage tanks by gas detection according to claim 2, characterized in that, In step S23, the amount of supplementary detection gas satisfies the following formula: or in, To supplement the detection of the amount of gaseous substances, This refers to the amount of detection gas injected during a single test.

8. The method for measuring the storage capacity and volume of an underground salt cavern gas storage facility by gas detection according to claim 1 or 2, characterized in that, Gas concentration detection was performed using a gas chromatography-flame ionization detector with a detection accuracy of ≤0.01ppm.

9. The method for measuring the storage capacity and volume of an underground salt cavern gas storage facility by gas detection according to claim 1 or 2, characterized in that, The formula for calculating the volume of a gas storage facility is: in, For the gas storage capacity, The amount of the working gas substance. The gas constant is For the temperature of the gas storage facility, This refers to the pressure in the gas storage facility.

10. The method for measuring the storage capacity and volume of underground salt cavern gas storage tanks by gas detection according to claim 2, characterized in that, The supplementary period in the continuous detection method satisfies: Otherwise, a new round of single-detection initialization will be triggered; in, is the high-pressure operating pressure of the gas storage tank at the start of gas extraction, and n is the number of interval cycles.

Images