Method for testing gas tightness of underground high-pressure gas storage and monitoring system

Abstract

The present application relates to the underground high-pressure gas storage gas tightness test method and monitoring system, relates to the gas tightness monitoring technical field.The method comprises the following steps: S1, according to the maximum operating pressure of gas storage, cavern diameter, the main surrounding rock class determines the pressurization gradient number of gas tightness experiment;S2, based on the pressurization gradient number, preset gas storage pressurization gas tightness test pressure time curve;S3, determine the number of pressure reduction gradient, and based on the number of pressure reduction gradient, preset gas storage pressure reduction gas tightness test pressure time curve;S4, according to the preset pressurization gas tightness test pressure time curve, carry out the pressurization gas tightness test of all pressurization gradient;S5, after the gas storage is pressurized to the maximum operating pressure and maintained for a period of time;S6, according to the preset pressure reduction gas tightness test pressure time curve, carry out the pressure reduction gas tightness test of all gradient number.The present application solves the problems of no early warning threshold of gas storage gas tightness test monitoring index, inaccurate gas tightness evaluation and the like.

Description

Technical Field

[0001] This invention belongs to the field of airtightness monitoring technology, specifically relating to the airtightness test method and monitoring system for underground high-pressure gas storage facilities. Background Technology

[0002] Compressed air energy storage is a technology that uses compressed air as a medium to store energy and generate electricity. Currently, underground caverns such as salt caverns and artificially excavated chambers are commonly used as gas storage facilities. Among them, rock-lined caverns can be constructed in widely distributed hard rock strata, offering greater flexibility in site selection and making them suitable for large-scale promotion.

[0003] Currently, gas storage facilities mainly adopt a combined load-bearing and sealing system of sealed steel plates, backfilled concrete, and surrounding rock. The structural stability and airtightness of the gas storage facility are key factors determining the safety of the project. However, with the increasing requirements for installed capacity and operating efficiency, the design pressure and inflation / deflation rate of gas storage facilities are also constantly increasing, posing a significant challenge to the structural stability and airtightness of the gas storage facilities.

[0004] Due to uncertainties in geological conditions and potential quality issues during construction, if the pressure and inflation / deflation rate of the gas storage facility are directly increased to operational levels during operation, the facility may experience sudden structural instability and leakage. Furthermore, backfill concrete may crack under high pressure. If the pressure is increased too quickly or excessively during the airtightness test, it could lead to excessive tensile failure of the concrete, preventing the formation of uniform radial cracks and affecting the concrete's load-bearing capacity. Summary of the Invention

[0005] The purpose of this invention is to provide a method and monitoring system for airtightness testing of underground high-pressure gas storage facilities, which solves the problems of structural instability / air leakage caused by overload airtightness testing when underground caverns are used as gas storage facilities, uneven distribution of cracks in backfill concrete affecting force transmission performance, as well as the technical difficulties of lack of quantitative standards for pressure / rate control, lack of early warning thresholds for monitoring indicators, and inaccurate assessment of structural stability and airtightness during airtightness testing.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: On the one hand, the present invention provides a method for testing the airtightness of an underground high-pressure gas storage facility, comprising the following steps: S1. Determine the number of pressurization steps for the airtightness test based on the maximum operating pressure of the gas storage facility, the diameter of the cavern, and the main surrounding rock type. S2. Based on the number of pressurization steps and the pressurization step size of the airtightness test, a time history curve of the pressurization airtightness test of the gas storage is preset, and the target pressure of each pressurization step is determined according to the time history curve of the pressurization airtightness test. S3. Determine the number of depressurization stages based on the number of pressurization stages, and based on the number of depressurization stages and the depressurization step size of the airtightness test, pre-set the depressurization airtightness test pressure time history curve of the gas storage tank, and determine the target pressure of each depressurization stage according to the depressurization airtightness test pressure time history curve. S4. Conduct pressurization airtightness tests for each pressurization stage according to the pressurization airtightness test pressure-time history curve. Pressurize stage by stage, starting with the first pressurization stage. After the pressure stabilizes at the target pressure of the first pressurization stage, maintain operation for a period of time and monitor the pressure. Once all monitored indicators meet the pressurization test requirements, proceed to the next pressurization stage. If any monitored indicator fails to meet the pressurization test requirements, suspend the pressurization test, inspect and repair the abnormal monitoring indicators in the gas storage tank, and restart the pressurization test once the monitoring indicators meet the pressurization test requirements. Continue until all pressurization stages are completed. S5. After completing all the pressurization stages in the pressurization test, pressurize the gas storage tank to the maximum operating pressure and maintain it for a period of time. Monitor the gas storage tank for any abnormal phenomena. If there are no abnormal phenomena, conduct the subsequent depressurization airtightness test. S6. Based on the pressure-time history curve of the pressure reduction test, conduct pressure reduction tests for all stages. Perform pressure reduction stage by stage. First, perform pressure reduction for the first stage. After the pressure stabilizes at the target pressure of the first stage, maintain operation for a period of time for pressure stabilization monitoring. Once all monitoring indicators meet the pressure reduction test requirements, proceed to the next stage of pressure reduction test. If any monitoring indicator fails to meet the pressure reduction test requirements, suspend the pressure reduction test, inspect and repair the abnormal monitoring indicators, and restart the pressure reduction test once the monitoring indicators meet the pressure reduction test requirements. Continue until all pressure reduction stages of the test are completed.

[0007] Furthermore, the formula for calculating the number of pressurization steps is as follows: = D /

[0008] in, The number of pressurization steps, The maximum operating pressure of the gas storage facility. The diameter of the gas storage chamber; The stability coefficient of the gas storage facility is determined based on the cavern diameter and the main surrounding rock type. The formula for calculating the pressurization step size in the airtightness test is as follows:

[0009] And, when <0.1MPa, take the standard value. =0.1MPa; in, For the pressure step size of the airtightness test, This is the loading pressure for the first pressurization stage.

[0010] Furthermore, the formula for calculating the number of pressure-reducing steps is as follows:

[0011] Where m is the number of voltage reduction steps. It is a rounding function. This is the ratio coefficient of the number of step-down to step-up voltage steps. ∈[1,3]; The formula for calculating the pressure reduction step size in the airtightness test is as follows:

[0012] in The pressure reduction step size for the airtightness test.

[0013] Furthermore, the pressure-time history curve of the pressurized airtightness test is expressed as follows:

[0014] in, The pressure-time history curve for the pressurized airtightness test; It is a time variable; 1 represents the number of stages in the pressurization ladder. =1, 2, ..., ; For the intervals of the pressurized airtightness test, The loading pressure for the first pressurization stage, This is the boost time coefficient. The pressure step size for the airtightness test; The pressure-time history curve of the pressure-reduced airtightness test is shown as follows:

[0015] In the formula: The pressure-time history curve for the pressure reduction and airtightness test; 2 represents the number of steps in the voltage reduction step. 2 = 1, 2, ... ; The interval between pressure reduction and airtightness test stages; This is the maximum design operating pressure of the gas storage facility; This is the time coefficient for pressure reduction; The pressure reduction step size for the airtightness test.

[0016] Furthermore, the monitoring indicators include at least the surrounding rock deformation, anchor bolt stress, backfill concrete cracks, shallow displacement deformation of the surrounding rock, and temperature change of the surrounding rock structure; the pressure test requires that all the monitoring indicators are within the pressure warning threshold range and that the shallow displacement deformation of the surrounding rock converges; the depressurization test requires that all the monitoring indicators are within the depressurization warning threshold range and that there is no sudden change in the anchor bolt stress.

[0017] Furthermore, the maintenance time after reaching the target pressure in the pressurization or depressurization airtightness test of each stage shall not be less than 30 minutes.

[0018] Furthermore, the pressurized airtightness test tiered cycle With the pressure reduction airtightness test interval cycle Set to 1-4 hours, of which .

[0019] Furthermore, in the pressurized airtightness test, the pressurization time coefficient is adjusted. To control the rate of pressurization of the gas storage tank, and the pressurization time coefficient of each pressurization stage in the pressurization airtightness test. The pressure reduction is gradually decreased; in the pressure reduction airtightness test, the pressure reduction time coefficient is adjusted. To control the rate of depressurization of the gas storage tank; the depressurization time coefficient of each depressurization step in the depressurization airtightness test. Decreasing step by step.

[0020] On the other hand, the present invention discloses a gas storage airtightness monitoring system, which is used to perform the above-mentioned method. The system includes a control unit, a data acquisition unit, a monitoring sensor unit, and an execution unit. The control unit is connected to the monitoring sensor unit through the data acquisition unit, and the control unit is also connected to the execution unit. The monitoring sensing unit includes a backfill concrete crack monitoring module, a surrounding rock deformation monitoring module, an airtightness monitoring module, and a sealing plug stress monitoring module. The backfill concrete crack monitoring module and the airtightness monitoring module are connected to the data acquisition unit via a demodulator; the surrounding rock deformation monitoring module and the sealing plug stress monitoring module are respectively connected to the data acquisition unit. The execution unit includes a depressurization module and a pressurization module. The control unit is connected to the depressurization module and the pressurization module respectively. The depressurization module and the pressurization module are connected to the sealing plug of the gas storage tank. The control unit realizes depressurization control of the gas storage tank through the depressurization module and pressurization control of the gas storage tank through the pressurization module.

[0021] The control unit has a built-in three-dimensional visualization module for processing the monitoring data of the monitoring sensor unit; Furthermore, the concrete crack monitoring module includes several strip-shaped grating fiber crack gauges, which are fixed to the circumferential reinforcement of the backfill concrete of the gas storage tank and are used to monitor the opening and expansion of cracks in the backfill concrete. The surrounding rock deformation monitoring module includes a multi-point displacement meter, which is buried inside the surrounding rock of the gas storage facility to monitor shallow displacement of the surrounding rock. The airtightness monitoring module includes a temperature-measuring optical cable, which is laid out circumferentially along the outer side of the sealing steel plate of the gas storage tank to identify leaks based on temperature changes. The sealing plug stress monitoring module includes several anchor stress gauges, which are installed on the anchoring anchors of the sealing plug. The anchoring anchors are tied to the reinforcing bars of the sealing plug and anchored to the surrounding rock to monitor the impact and deformation of the sealing plug. The grating fiber optic crack gauge and the multi-point displacement gauge are installed at the monitoring section, and the spacing of the monitoring section is determined according to different surrounding rock grades. The pressure reduction module includes an expander, and the pressure increase module includes a compressor. Both the expander and the compressor are connected to the inflation / deflation pipes of the sealing plug.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention uses a stepped pressurization, stabilization and depressurization test method to accurately monitor multiple indicators such as concrete cracks, surrounding rock deformation, air tightness and sealing plug stress of the gas storage tank. It effectively solves the problem of structural safety and air tightness monitoring under high pressure conditions in underground high-pressure gas storage tanks. The test process is safe and controllable, and the monitoring data is accurate and reliable. It can be widely used in air tightness testing and safety monitoring of various underground high-pressure gas storage tank projects. Attached Figure Description

[0023] Figure 1 This is a flowchart of the airtightness test method for underground high-pressure gas storage in an embodiment of the present invention; Figure 2 This is a pressure-time history curve of the airtightness test of the underground high-pressure gas storage facility according to an embodiment of the present invention; Figure 3 This is a structural diagram of the gas storage airtightness monitoring system according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the layout of the gas storage airtightness monitoring system according to an embodiment of the present invention.

[0024] Reference numerals: 1. Sealing steel plate; 2. Backfill concrete; 3. Sealing plug; 4. Multi-point displacement gauge; 5. Grating fiber optic crack gauge; 6. Temperature measuring optical cable; 7. Anchor bolt stress gauge; 8. Inflation / depression pipeline. Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0026] This embodiment discloses a method for testing the airtightness of an underground high-pressure gas storage facility, specifically including the following steps: S1. Determine the number of pressurization steps for the airtightness test based on the design pressure of the gas storage facility, the diameter of the chamber, and the main surrounding rock type. The formula for calculating the number of pressurization steps is as follows:

[0027] in, The number of pressurization steps, This is the maximum operating pressure of the gas storage facility, expressed in MPa. The diameter of the gas storage chamber is expressed in meters (m). The stability coefficient of the gas storage facility is determined based on the cavern diameter and the main surrounding rock type. The stability coefficient of the gas storage facility is determined based on the cavern diameter and the main surrounding rock type. This embodiment provides the range of values ​​for the stability coefficient, see Table 1.

[0028] Table 1. Stability coefficient values ​​for gas storage facilities

[0029] This embodiment uses a gas storage facility as an example. The gas storage facility has a cavern diameter of 10m, a maximum designed operating pressure of 10MPa, and the surrounding rock is mainly Class III rock. A rock-lined cavern is used as the gas storage container, and C30 concrete is used for backfill. The design value of the tensile strength of the backfill concrete is... The design strength is 2.01 MPa, and the sealing plug anchor rod uses HRB400 grade steel bars with a design strength of 360 MPa. From Table 1, we know that A=12, n=25 / 3, rounding up, n≈9.

[0030] S2. Based on the number of pressurization steps and the pressurization step size of the airtightness test, a time history curve of the pressurization airtightness test of the gas storage is preset, and the target pressure of each pressurization step is determined according to the time history curve of the depressurization airtightness test. The pressure-time history curve for the pressurized airtightness test is shown as follows:

[0031] in, The pressure-time history curve for the pressurized airtightness test; 1 represents the number of stages in the pressurization ladder. 1 = 1, 2, ... ; The pressurized airtightness test interval cycle, the pressurized airtightness test interval cycle The typical setting is 1-4 hours, as in this embodiment. =2h, The loading pressure for the first pressurization stage, The boost time factor decreases from 0.8 to 0.2. The pressure step size for the airtightness test; Before calculating the pressure time history curve of the gas storage tank's pressurization airtightness test, the pressurization step size for the airtightness test must first be determined. The formula for calculating the pressurization step size for the airtightness test is as follows:

[0032] And, when <0.1MPa, take the standard value. =0.1MPa.

[0033] During the pressurized airtightness test, when the pressure in the gas storage tank reached the crack initiation load, the tensile stress in the backfill concrete decreased rapidly, the crack width suddenly increased, and energy was released instantaneously, forming the initial crack. As the internal pressure continued to increase, the crack continued to expand, increasing in width, eventually forming a radial through crack along the perimeter of the cavity. To ensure the radial force transmission performance of the backfill concrete, it is crucial to minimize the formation of too many cracks in the concrete during pressurization and to encourage the cracks to distribute radially as much as possible. Therefore, the loading pressure of the first pressurization stage... The loading pressure should not be too high to avoid excessive initial cracking in the backfill concrete. Design the loading pressure for the first pressurized stage. The calculation formula is:

[0034] in, This refers to the design value of the tensile strength of the backfill concrete; Partial coefficients, = Rounding to one decimal place, in this embodiment, =0.3; =2.01×0.3=0.603MPa, rounded down to one decimal place, the value is 0.6MPa; but, = =1.175MPa, rounded down to one decimal place, the value is 1.1MPa.

[0035] Based on the pressurization step size of the airtightness test, the target pressures for the nine pressurization stages were determined to be 0.6 MPa, 1.775 MPa, 2.95 MPa, 4.125 MPa, 5.3 MPa, 6.475 MPa, 7.65 MPa, 8.825 MPa, and 10 MPa, respectively.

[0036] S3, determine the number of depressurization stages based on the number of pressurization stages, and determine the target pressure of each depressurization stage based on the number of depressurization stages and the depressurization step size of the airtightness test of the pre-set depressurization airtightness test pressure time history curve of the gas storage tank according to the depressurization airtightness test pressure time history curve. The pressure-time history curve for the pressure drop airtightness test is shown as follows:

[0037] In the formula: The pressure-time history curve for the pressure reduction and airtightness test; 2 represents the number of steps in the voltage reduction step. =1, 2, ..., ; The interval between pressure reduction and airtightness test stages; This is the maximum design operating pressure of the gas storage facility; This is the time coefficient for pressure reduction; The pressure reduction step size for the airtightness test; First, determine the number of pressure-reducing elevator sections. The number of pressure-reducing elevator sections is determined based on the number of pressure-increasing elevator sections. The calculation formula is as follows:

[0038] Where m is the number of voltage reduction steps. It is a rounding function. This is the ratio coefficient of the number of step-down to step-up voltage steps. ∈[1,3], Configure it reasonably according to the needs of the project. The larger the pressure drop, the shorter the airtightness test time. In this embodiment... If we take 2, then m = 4.

[0039] Secondly, the pressure reduction step size for the airtightness test is calculated based on the number of pressure reduction steps. The formula for calculating the pressure reduction step size for the airtightness test is as follows:

[0040] in To calculate the pressure reduction step size for the airtightness test, 2.5MPa; Based on the pressure reduction step size of the airtightness test, the target pressures for the four pressure reduction stages are determined to be 7.5 MPa, 5 MPa, 2.5 MPa, and 0 MPa, respectively.

[0041] S4. Conduct pressurization airtightness tests for each pressurization stage according to the preset pressurization airtightness test pressure-time history curve. Pressurize stage by stage, starting with the first pressurization stage. After the pressure stabilizes at the target pressure of the first pressurization stage, maintain operation for at least 30 minutes and monitor the pressure. Once all monitored indicators meet the pressurization test requirements, proceed to the next pressurization stage. If any monitored indicator fails to meet the pressurization test requirements, suspend the pressurization test, inspect and repair the abnormal monitoring indicators in the gas storage tank, and restart the pressurization test once the monitoring indicators meet the pressurization test requirements. Continue until all pressurization stages are completed. The monitoring indicators include at least the surrounding rock deformation, anchor bolt stress, backfill concrete cracks, shallow displacement deformation of the surrounding rock, and temperature change of the surrounding rock structure; the pressure test requires that all monitoring indicators are within the pressure warning threshold range, and that the shallow displacement deformation of the surrounding rock converges.

[0042] S5. After completing the pressurization test of all pressurization stages, pressurize the gas storage tank to the maximum operating pressure of 10MPa and maintain it for at least 30 minutes. Then monitor the gas storage tank for any abnormal phenomena. If there are no abnormal phenomena, conduct the subsequent depressurization airtightness test. The presence of abnormal phenomena is determined by the temperature change of the surrounding rock structure to determine if the gas storage tank is leaking. If there is a leak, suspend the airtightness test and carry out maintenance. Continue the subsequent depressurization airtightness test after the abnormal phenomena disappear.

[0043] S6. Based on the preset pressure-time history curve for the pressure reduction test, conduct pressure reduction tests for each pressure reduction stage. Perform pressure reduction stage by stage, starting with the first stage. After the pressure stabilizes at the target pressure of the first stage, maintain operation for at least 30 minutes for pressure monitoring. Once all monitored indicators meet the pressure reduction test requirements, proceed to the next stage. If any monitored indicator fails to meet the pressure reduction test requirements, pause the test, inspect and repair any abnormal areas, and restart the test once the monitored indicators meet the requirements. Continue this process until all stages of the pressure reduction test are completed. The pressure reduction test requires all monitored indicators to be within the pressure reduction warning threshold and no sudden changes in anchor bolt stress.

[0044] Figure 2 The pressure time history curves for the entire airtightness test process of the underground high-pressure gas storage facility, including the pressure time history curves for the pressurized airtightness test and the pressure time history curves for the depressurized airtightness test, are shown in the embodiment of the present invention.

[0045] In this embodiment, the maintenance running time in the pressurization airtightness test or depressurization airtightness test of each step is not less than 30 minutes.

[0046] Furthermore, in the pressurized airtightness test, the pressurization time coefficient is adjusted. To control the rate of pressurization of the gas storage facility, the pressurization time coefficient of each pressurization stage in the pressurization airtightness test. Decrease step by step; in the pressure reduction airtightness test, the pressure reduction time coefficient is adjusted. To control the rate of depressurization of the gas storage facility; the depressurization time coefficient of each depressurization stage in the depressurization airtightness test. Decreasing step by step.

[0047] In this implementation, to ensure that cracks in the backfill concrete can propagate radially, the pressure increase rate should be reasonably controlled during pressurization. Therefore, the pressure increase rate can be adjusted based on the results of concrete crack monitoring. The pressure increase rate is adjusted by adjusting the pressure increase time coefficient. Control is implemented. Boost time coefficient. A value of 0.2-0.8 is recommended. If concrete cracks propagate too quickly or too many new cracks appear, the pressure increase time coefficient can be appropriately increased. .

[0048] Under pressure, the surrounding rock, bearing the majority of the pressure load, will undergo a certain degree of deformation and displacement. This includes the shallow displacement and deformation of the surrounding rock in each pressurization or depressurization stage. From elastic deformation With plastic deformation The test consists of two parts, during which the deformation of the surrounding rock is monitored using multi-point displacement gauges. After each pressurization stage and depressurization stage, once the target pressure has stabilized, the shallow displacement and deformation of the surrounding rock are observed. If the shallow displacement and deformation of the surrounding rock gradually converges and tends to stabilize (i.e., the convergence rate is <2 mm / h), it indicates that the surrounding rock structure is stable. If the shallow displacement and deformation of the surrounding rock continues to increase and does not converge (i.e., the convergence rate is ≥2 mm / h), or suddenly fluctuates violently, it indicates that there may be potential instability at the monitoring section, and pressurization / depressurization should be stopped immediately.

[0049] In addition, the shallow displacement and deformation of the surrounding rock corresponding to the pressure time history were recorded during the airtightness test. The plastic deformation of the surrounding rock can be obtained by comparing the shallow displacement deformation of the surrounding rock during the pressurization stage with that during the depressurization stage under the same pressure conditions. .

[0050] The airtightness test method for underground high-pressure gas storage in this embodiment mainly includes three stages: pressurization, pressure stabilization, and pressure reduction. The pressurization stage gradually increases the internal pressure in a step-like manner to test the structural stability and airtightness characteristics of the gas storage during pressurization. The pressure stabilization stage tests the airtightness of the gas storage under maximum pressure conditions and the deformation and convergence characteristics of the surrounding rock. The pressure reduction stage tests the rebound deformation characteristics of the surrounding rock during the gas release process and the impact of the release rate on the sealing plug.

[0051] On the other hand, the present invention also discloses a gas storage airtightness monitoring system for performing the above-mentioned monitoring method, such as... Figure 3 As shown, the system includes a control unit, a data acquisition unit, a monitoring and sensing unit, and an execution unit. The control unit is connected to the monitoring and sensing unit through the data acquisition unit, and the control unit is also connected to the execution unit.

[0052] The monitoring sensing unit includes a backfill concrete crack monitoring module, a surrounding rock deformation monitoring module, an air tightness monitoring module, and a sealing plug stress monitoring module. The backfill concrete crack monitoring module and the air tightness monitoring module are connected to the data acquisition unit through a demodulator; the surrounding rock deformation monitoring module and the sealing plug stress monitoring module are respectively connected to the data acquisition unit. The execution unit includes a depressurization module and a pressurization module. The control unit is connected to the depressurization module and the pressurization module respectively. The depressurization module and the pressurization module are connected to the sealing plug of the gas storage tank. The control unit realizes depressurization control of the gas storage tank through the depressurization module and pressurization control of the gas storage tank through the pressurization module. The sealing plug is equipped with a gas filling and venting pipeline for gas filling during pressurization test or gas venting during depressurization test. The depressurization module includes an expander, and the pressurization module includes a compressor. Both the expander and the compressor are connected to the gas filling and venting pipeline of the sealing plug.

[0053] The control unit is a computer with a built-in 3D visualization module for processing monitoring data from the sensing units.

[0054] In this embodiment, as Figure 4 As shown, the concrete crack monitoring module is used to collect crack indicators of backfill concrete 2 in order to monitor the opening and expansion of cracks in backfill concrete 2. The concrete crack monitoring module includes several strip-shaped grating fiber crack gauges 5, which are fixed on the circumferential reinforcement of the backfill concrete 2 of the gas storage tank. The surrounding rock deformation monitoring module is used to collect shallow displacement and deformation indicators of the surrounding rock. The surrounding rock deformation monitoring module includes a multi-point displacement meter 4, which is buried inside the surrounding rock of the gas storage. The air tightness monitoring module is used to collect temperature change indicators of the surrounding rock structure and identify whether the gas storage tank is leaking based on the temperature change of the surrounding rock structure. The air tightness monitoring module includes a temperature measuring optical cable 6, which is arranged circumferentially along the outer side of the sealing steel plate 1 of the gas storage tank. The sealing plug 3 stress monitoring module is used to monitor the impact and deformation of the sealing plug 3. The sealing plug 3 stress monitoring module includes the sealing plug 3 and several anchor stress gauges 7. The anchor stress gauges 7 are installed on the anchoring anchors of the sealing plug 3. The anchoring anchors are tied to the reinforcing bars of the sealing plug 3 and anchored to the surrounding rock.

[0055] Among them, the grating fiber crack gauge 5 and the multi-point displacement gauge 4 are set at the monitoring section. The spacing of the monitoring section is determined according to different surrounding rock grades, as shown in Table 2. The typical monitoring section spacing is referenced in the table.

[0056] Table 2. Reference Table for Typical Monitoring Section Spacing

[0057] In addition to setting up monitoring sections according to the surrounding rock level, monitoring sections need to be densified according to the following four situations, including (1) the start and end points and turning points of the gas storage; (2) the abrupt change in the surrounding rock level, such as the junction of Class III surrounding rock and Class IV surrounding rock; (3) within 10m before and after the sealing plug; (4) the fracture zone and dense joint zone that appear during construction.

[0058] The pressurization rate of the boosting module during the final pressurization stage should not be less than the actual inflation rate of the gas storage facility, and the depressurization rate of the depressurization module during the final depressurization stage should not be less than the actual deflation rate of the gas storage facility. Simultaneously, during the airtightness test, both the pressurization rate during the pressurization stage and the depressurization rate during the depressurization stage continuously increase, increasing the impact on the sealing plug 3. If the peak stress of the anchor stress gauge 7 on the sealing plug 3... Less than the design strength value of the anchor bolt If the stability of the sealing plug 3 is satisfactory, then the requirements are met.

[0059] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of this invention and are defined by the claims.

Claims

1. A method for testing the airtightness of an underground high-pressure gas storage facility, characterized in that, Includes the following steps: S1. Determine the number of pressurization steps for the airtightness test based on the maximum operating pressure of the gas storage facility, the diameter of the cavern, and the main surrounding rock type. S2. Based on the number of pressurization steps and the pressurization step size of the airtightness test, a time history curve of the pressurization airtightness test of the gas storage is preset, and the target pressure of each pressurization step is determined according to the time history curve of the pressurization airtightness test. S3. Determine the number of depressurization stages based on the number of pressurization stages, and based on the number of depressurization stages and the depressurization step size of the airtightness test, pre-set the depressurization airtightness test pressure time history curve of the gas storage tank, and determine the target pressure of each depressurization stage according to the depressurization airtightness test pressure time history curve. S4. Conduct pressurization airtightness tests for each pressurization stage according to the pressurization airtightness test pressure-time history curve. Pressurize stage by stage, starting with the first pressurization stage. After the pressure stabilizes at the target pressure of the first pressurization stage, maintain operation for a period of time and monitor the pressure. Once all monitored indicators meet the pressurization test requirements, proceed to the next pressurization stage. If any monitored indicator fails to meet the pressurization test requirements, suspend the pressurization test, inspect and repair the abnormal monitoring indicators in the gas storage tank, and restart the pressurization test once the monitoring indicators meet the pressurization test requirements. Continue until all pressurization stages are completed. S5. After completing all the pressurization stages in the pressurization test, pressurize the gas storage tank to the maximum operating pressure and maintain it for a period of time. Monitor the gas storage tank for any abnormal phenomena. If there are no abnormal phenomena, conduct the subsequent depressurization airtightness test. S6. Based on the pressure-time history curve of the pressure reduction test, conduct pressure reduction tests for all stages. Perform pressure reduction stage by stage, starting with the first stage of pressure reduction. After the pressure stabilizes at the target pressure of the first stage, maintain operation for a period of time for pressure stabilization monitoring. Once all monitoring indicators meet the pressure reduction test requirements, proceed to the next stage of pressure reduction test. If any monitoring indicator fails to meet the pressure reduction test requirements, suspend the pressure reduction test, inspect and repair any abnormal monitoring indicators, and restart the pressure reduction test once the monitoring indicators meet the pressure reduction test requirements. Continue until all stages of pressure reduction tests are completed. In the pressurized airtightness test, the pressurization time coefficient is adjusted. To control the rate of pressurization of the gas storage tank, and the pressurization time coefficient of each pressurization stage in the pressurization airtightness test. The pressure reduction process is used to verify the structural stability and airtightness of the gas storage tank during pressurization; the depressurization airtightness test involves adjusting the depressurization time coefficient. To control the rate of depressurization of the gas storage tank; the depressurization time coefficient of each depressurization step in the depressurization airtightness test. The stepwise decrease is used to test the rebound deformation of the surrounding rock during the gas release process of the gas storage facility and the impact of the gas release rate on the sealing plug.

2. The method for testing the airtightness of an underground high-pressure gas storage facility according to claim 1, characterized in that, The formula for calculating the number of pressurization steps is: = D / in, The number of pressurization steps, The maximum operating pressure of the gas storage facility. The diameter of the gas storage chamber; The stability coefficient of the gas storage facility is determined based on the cavern diameter and the main surrounding rock type. The formula for calculating the pressurization step size in the airtightness test is as follows: And, when <0.1MPa, take the standard value. =0.1MPa; in, For the pressure step size of the airtightness test, This is the loading pressure for the first pressurization stage.

3. The method for testing the airtightness of an underground high-pressure gas storage facility according to claim 2, characterized in that, The formula for calculating the number of pressure reduction steps is: Where m is the number of voltage reduction steps. It is a rounding function. This is the ratio coefficient of the number of step-down to step-up voltage steps. ∈[1,3]; The formula for calculating the pressure reduction step size in the airtightness test is as follows: in The pressure reduction step size for the airtightness test.

4. The method for testing the airtightness of an underground high-pressure gas storage facility according to claim 3, characterized in that, The pressure-time history curve of the pressurized airtightness test is shown as follows: in, The pressure-time history curve for the pressurized airtightness test; It is a time variable; 1 represents the number of stages in the pressurization ladder. =1, 2, ..., ; For the intervals of the pressurized airtightness test, The loading pressure for the first pressurization stage, This is the boost time coefficient. The pressure step size for the airtightness test; The pressure-time history curve of the pressure-reduced airtightness test is shown as follows: In the formula: The pressure-time history curve for the pressure reduction and airtightness test; 2 represents the number of steps in the voltage reduction step. 2 = 1, 2, ... ; The interval between pressure reduction and airtightness test stages; This is the maximum design operating pressure of the gas storage facility; This is the time coefficient for pressure reduction; The pressure reduction step size for the airtightness test.

5. The method for testing the airtightness of an underground high-pressure gas storage facility according to claim 1, characterized in that, The monitoring indicators include at least the surrounding rock deformation, anchor bolt stress, backfill concrete cracks, shallow displacement deformation of the surrounding rock, and temperature change of the surrounding rock structure; the pressure test requires that all the monitoring indicators are within the pressure warning threshold range and that the shallow displacement deformation of the surrounding rock converges; the depressurization test requires that all the monitoring indicators are within the depressurization warning threshold range and that there is no sudden change in the anchor bolt stress.

6. The method for testing the airtightness of an underground high-pressure gas storage facility according to claim 1, characterized in that, The maintenance time after reaching the target pressure in the pressurization or depressurization airtightness test of each stage shall not be less than 30 minutes.

7. The method for testing the airtightness of an underground high-pressure gas storage facility according to claim 4, characterized in that, Pressure airtightness test tiered cycle With the pressure reduction airtightness test interval cycle Set to 1-4 hours, of which ≥ .

8. A gas storage facility airtightness monitoring system, characterized in that, The system is used to perform the method as described in any one of claims 1-7. The system includes a control unit, a data acquisition unit, a monitoring and sensing unit, and an execution unit. The control unit is connected to the monitoring and sensing unit through the data acquisition unit, and the control unit is also connected to the execution unit. The monitoring sensing unit includes a backfill concrete crack monitoring module, a surrounding rock deformation monitoring module, an airtightness monitoring module, and a sealing plug stress monitoring module. The backfill concrete crack monitoring module and the airtightness monitoring module are connected to the data acquisition unit via a demodulator; the surrounding rock deformation monitoring module and the sealing plug stress monitoring module are respectively connected to the data acquisition unit. The execution unit includes a depressurization module and a pressurization module. The control unit is connected to the depressurization module and the pressurization module respectively. The depressurization module and the pressurization module are connected to the sealing plug of the gas storage tank. The control unit realizes depressurization control of the gas storage tank through the depressurization module and pressurization control of the gas storage tank through the pressurization module. The control unit has a built-in three-dimensional visualization module for processing the monitoring data from the monitoring sensor unit.

9. The monitoring system according to claim 8, characterized in that, The concrete crack monitoring module includes several strip-shaped grating fiber crack gauges, which are fixed to the circumferential reinforcement of the backfill concrete in the gas storage tank and are used to monitor the opening and expansion of cracks in the backfill concrete. The surrounding rock deformation monitoring module includes a multi-point displacement meter, which is buried inside the surrounding rock of the gas storage facility to monitor shallow displacement of the surrounding rock. The airtightness monitoring module includes a temperature-measuring optical cable, which is laid out circumferentially along the outer side of the sealing steel plate of the gas storage tank to identify leaks based on temperature changes. The sealing plug stress monitoring module includes several anchor stress gauges, which are installed on the anchoring anchors of the sealing plug. The anchoring anchors are tied to the reinforcing bars of the sealing plug and anchored to the surrounding rock to monitor the impact and deformation of the sealing plug. The grating fiber optic crack gauge and the multi-point displacement gauge are installed at the monitoring section, and the spacing of the monitoring section is determined according to different surrounding rock grades. The pressure reduction module includes an expander, and the pressure increase module includes a compressor. Both the expander and the compressor are connected to the inflation / deflation pipes of the sealing plug.

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