An underground high-pressure gas storage surrounding rock gas load interlocking pressure relief control method

Abstract

This invention relates to a method for controlling the interlocking depressurization of surrounding rock in an underground high-pressure gas storage facility. Near-field inner-ring monitoring boreholes and far-field outer-ring monitoring boreholes are arranged around the main test borehole, forming radial monitoring zones according to radial correspondence. Low-pressure preloading is used to calibrate the acoustic emission background, propagation attenuation, channel confidence, outer-ring surrounding rock stress, and pore pressure baseline. During formal loading, acoustic emission events are identified and weighted, and the radial fracture penetration index, source radial migration index, and changes in outer-ring stress and pore pressure are calculated. Based on a three-level interlocking threshold, deceleration loading, pressure holding observation, step-by-step depressurization, or rapid depressurization are controlled. This method can identify the risk of fracture propagation in local directions and improves the safety and reliability of gas load testing through hardware safety interlocks.

Description

Technical Field

[0001] This invention belongs to the field of intelligent monitoring and early warning, high-pressure gas in-situ loading test and safety interlock control technology for underground engineering, specifically involving a method for interlocking depressurization control of surrounding rock gas load in underground high-pressure gas storage. Background Technology

[0002] The surrounding rock of underground high-pressure gas storage facilities must withstand high internal pressure gas loads for extended periods, and its bearing capacity and fracture propagation characteristics directly affect the safety of the gas storage facility. To evaluate the bearing capacity of the surrounding rock, a main test borehole can be drilled in the surrounding rock of an underground chamber or test tunnel, and a high-pressure radial loading unit can be arranged inside the borehole to apply radial loads to the borehole wall using high-pressure gas.

[0003] Current high-pressure loading tests mostly rely on single-point acoustic emission, pressure, stress, or global monitoring thresholds for load reduction, pressure maintenance, or pressure relief control. However, during gas loading, local microcracks in the near field do not necessarily indicate rock instability. What truly needs to be identified is whether the fracturing activity extends outwards along a certain direction into the outer control area. If a global summation or average threshold is used, the outward expansion signal in the dangerous direction may be masked by other stable directions; if only single-point acoustic emission is relied upon, it is easily affected by high-pressure gas seepage, jetting, and pipeline vibration noise.

[0004] Therefore, it is necessary to establish a pneumatic loading safety control method that uses radial partitions as the basic unit, integrates the acoustic emission of the inner and outer rings, the stress of the outer rings and the air pressure in the outer ring pores, and directly links the valve group to depressurize. Summary of the Invention

[0005] The purpose of this invention is to provide a gas-load interlocking depressurization control method for surrounding rock of underground high-pressure gas storage facilities, which solves the problems in existing in-situ gas load testing, such as difficulty in distinguishing between permissible near-field damage and outer-circle hazard expansion, easy misjudgment due to gas flow noise, easy masking of local hazard direction by global averaging, and unclear correspondence between monitoring criteria and depressurization valve group actions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] A method for interlocking depressurization control of surrounding rock gas load in an underground high-pressure gas storage facility includes the following steps: S1. Arrange near-field inner ring monitoring holes and far-field outer ring monitoring holes around the main test hole from near to far. Form a radial monitoring zone by combining at least one near-field inner ring monitoring hole and at least one far-field outer ring monitoring hole located in the same radial monitoring profile, and use each radial monitoring zone as a monitoring data processing and interlocking discrimination unit. S2. Before the formal air load loading, perform low-pressure preload calibration to obtain the acoustic emission background baseline, acoustic emission propagation attenuation correction coefficient, channel confidence coefficient, gas flow noise characteristics, outer ring surrounding rock stress baseline and outer ring pore gas pressure baseline of each radial monitoring zone, and generate the first-level interlocking threshold, second-level interlocking threshold and ultimate interlocking threshold. S3. During the formal air load loading process, the sliding time window is used as the discrimination unit to obtain the loading pressure of the main test hole and the acoustic emission data of the inner ring, outer ring, outer ring surrounding rock stress and outer ring pore air pressure of each radial monitoring zone, and to identify gas flow noise and assign event weights to the acoustic emission events. S4. Based on the weighted acoustic emission events, acoustic emission background baseline, acoustic emission propagation attenuation correction coefficient, and channel confidence coefficient, generate inner circle corrected acoustic emission response and outer circle corrected acoustic emission response. Generate zonal radial fracture penetration index according to the relative relationship between the two. Generate source radial migration index based on acoustic emission source location results. Generate outer circle surrounding rock stress change and outer circle pore air pressure change. S5. Compare the radial fracture penetration index, the radial migration index of the seismic source, the absolute value of the change in stress of the outer ring surrounding rock and the absolute value of the change in pore air pressure of the outer ring with the corresponding first-level interlocking threshold, second-level interlocking threshold and ultimate interlocking threshold respectively to determine the interlocking status of each radial monitoring zone. S6. Based on the interlock status and the loading pressure of the main test hole, control the intake pressure regulating valve group, pressure holding valve group, stepped pressure relief valve group and rapid pressure relief valve group to perform normal loading, deceleration loading, pressure holding observation, stepped pressure relief or rapid pressure relief, and trigger the corresponding control action when any radial monitoring zone reaches the corresponding interlock condition.

[0008] Beneficial effects Compared with the prior art, the present invention has the following beneficial effects.

[0009] First, the present invention uses radial monitoring zones as the basic control unit, which can identify the directional risk of rupture activity spreading from the near-field inner circle to the far-field outer circle, and avoid the dangerous direction being masked by global averaging.

[0010] Second, the present invention interlocks the radial fracture penetration index, the radial migration index of the seismic source, the stress of the outer surrounding rock, and the pore gas pressure of the outer ring, which can distinguish between near-field permissible damage, outer ring dangerous expansion, and gas noise interference.

[0011] Third, the present invention establishes background baseline, noise characteristics and classification thresholds through low-pressure preloading, so that the criteria can be adapted to the on-site rock mass conditions and sensor status.

[0012] Fourth, this invention directly correlates the interlock levels with intake pressure regulation, pressure holding, stepped pressure relief, and rapid pressure relief actions, thereby improving the safety and control reliability of high-pressure air load in-situ loading tests. Attached Figure Description

[0013] Figure 1 This is the overall flowchart of the underground high-pressure gas storage surrounding rock gas load interlocking depressurization control method of the present invention; Figure 2 This is a schematic diagram of the planar arrangement of the main test hole, the near-field inner ring monitoring hole array, and the far-field outer ring monitoring hole array of the present invention; Figure 3 This is a schematic diagram of the radial monitoring zones and the same radial monitoring profile of the present invention; Figure 4 This is a schematic diagram of the composition of the high-pressure gas in-situ loading system and the surrounding rock array monitoring system of the present invention; Figure 5 This is a schematic diagram illustrating the calculation of the radial fracture penetration index of the present invention. Figure 6 This is a schematic diagram illustrating the calculation of the radial migration index of the seismic source in this invention.

[0014] Explanation of reference numerals in the attached figures: 1. Main test hole; 2. High-pressure radial loading unit; 3. Near-field inner ring monitoring hole; 4. Far-field outer ring monitoring hole; 5. Inner ring acoustic emission sensor; 6. Outer ring acoustic emission sensor; 7. Outer ring surrounding rock stress sensor; 8. Outer ring pore air pressure sensor; 9. High-pressure air source; 10. Inlet pressure regulating valve group; 11. Pressure holding valve group; 12. Stepped pressure relief valve group; 13. Quick pressure relief valve group; 14. Pressure sensor; 15. Acoustic emission acquisition module; 16. Outer ring low-frequency acquisition module; 17. Hardware synchronization module; 18. Edge controller; 19. PLC controller; 20. Safety interlock circuit; 21. Host computer; 22. First radial monitoring zone; 23. Second radial monitoring zone; 24. Third radial monitoring zone; 25. Fourth radial monitoring zone. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are used to explain the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. Without departing from the technical concept of the present invention, the number of monitoring holes, the spacing between monitoring holes, the sensor type, the valve group form, the threshold coefficient, the time window length, and the control parameters can all be adaptively adjusted according to the field conditions.

[0016] I. Symbol and Dimensional Conventions To avoid ambiguity, this manual adopts the following standardized notation and dimensional conventions.

[0017] This represents the total number of radial monitoring zones. It is a positive integer; For radial monitoring zone number, satisfying:

[0018] This is the acoustic emission channel number. This refers to the sequence number of the acoustic emission event. To formally load the sliding time window sequence, The sequence number represents the background sliding time window; all sequence numbers are positive integers.

[0019] The length of the sliding time window has a time dimension; For the first The end time of a formal loading sliding time window, which has a time dimension.

[0020] The number of effective background sliding time windows; For the first The end time of each effective background sliding time window has a time dimension, where:

[0021] Used as a position marker for the inner and outer rings, dimensionless, and satisfying the following:

[0022] in, Indicates the inner circle. Indicates the outer ring.

[0023] It is a dimensionless identifier for the interlocking level and satisfies:

[0024] in, Indicates the first level of interlocking. Indicates a level two interlocking system. Indicates the ultimate interlocking level; the superscript of the interlocking level It does not indicate length.

[0025] The radial distance from the center of the near-field inner ring monitoring hole to the center of the main test hole. Let be the radial distance from the outermost monitoring aperture in the far field to the center of the main test aperture. Both and have the dimension of length and satisfy the following:

[0026] In this instruction manual, the superscript This represents background statistics obtained during the low-pressure preloading phase or the stable background phase; superscript This indicates the statistic after weighting acoustic emission events; the wavy line above the symbol indicates the statistic after correction to the lower limit of the preset standard deviation; the subscript... Indicates the inner circle, subscript Indicates the outer ring, subscript Indicates quantities related to positioning error, subscript and These represent the lower limit and the maximum value, respectively.

[0027] For physical quantities of the same type, consistent units are used throughout the calculation process. Length can be expressed in meters or millimeters; time can be expressed in seconds or milliseconds; acoustic emission event energy is expressed in joules or energy units standardized by the acoustic emission acquisition system; stress and pressure are expressed in Pascals, kilopascals, or megapascals; and units are kept consistent within the same set of formulas.

[0028] II. System Composition and Radial Monitoring Zones Specifically, refer to Figure 1 This invention discloses a method for controlling the interlocking depressurization of surrounding rock gas in an underground high-pressure gas storage facility, including S1, establishing radial monitoring zones. Specifically, this includes arranging near-field inner-ring monitoring holes and far-field outer-ring monitoring holes around the main test hole from near to far, forming a radial monitoring zone with at least one near-field inner-ring monitoring hole and at least one far-field outer-ring monitoring hole located in the same radial monitoring profile, and using each radial monitoring zone as a monitoring data processing and interlocking discrimination unit. This step illustrates that: like Figures 2 to 4 As shown, a main test hole 1 is drilled in the rock mass to be tested, and a high-pressure radial loading unit 2 is arranged inside the main test hole 1. The high-pressure radial loading unit 2 can be a pressure-resistant bag-type loading unit, an elastic sleeve-type loading unit, a segmented radial loading unit, or other loading units that can apply radial pressure to the borehole wall of the main test hole 1 under the action of high-pressure gas.

[0029] Figure 4 The solid black line in the middle represents the high-pressure gas pipeline. The high-pressure radial loading unit 2 is connected to the high-pressure gas source 9 through the high-pressure gas pipeline. The high-pressure pipeline is equipped with an inlet pressure regulating valve group 10, a pressure holding valve group 11, a stepped pressure relief valve group 12, a quick pressure relief valve group 13, and a pressure sensor 14.

[0030] The intake pressure regulating valve assembly 10 is used to control the pressure increase rate and intake volume; the pressure holding valve assembly 11 is used to keep the pressure of the main test hole within a preset allowable fluctuation range; the stepped pressure relief valve assembly 12 is used to release pressure step by step according to a preset pressure drop rate or pressure drop step size; the rapid pressure relief valve assembly 13 is used to quickly release the pressure in the high-pressure radial loading unit 2 when the ultimate interlocking conditions are met; and the pressure sensor 14 is used to collect the loading pressure in the main test hole 1 in real time.

[0031] A near-field inner ring monitoring hole 3 and a far-field outer ring monitoring hole 4 are set around the main test hole 1. An inner ring acoustic emission sensor 5 is installed in the near-field inner ring monitoring hole 3; an outer ring acoustic emission sensor 6, an outer ring surrounding rock stress sensor 7, and an outer ring pore air pressure sensor 8 are installed in the far-field outer ring monitoring hole 4.

[0032] It should be noted that, Figure 4 The red single-arrow dashed line indicates the pressurized gas path. The gas enters the high-pressure radial loading unit 2 from the high-pressure gas source 9 through the inlet pressure regulating valve group 10, the pressure holding valve group 11, and the pressure sensor 14. The blue single-arrow dashed line indicates the depressurized gas path. When depressurizing, the gas can be depressurized slowly through the stepped depressurization valve group 12 or quickly through the fast depressurization valve group 13.

[0033] Based on the above radial monitoring zoning construction method, this embodiment further limits the number and arrangement of near-field inner ring monitoring holes and far-field outer ring monitoring holes: In a preferred embodiment, four near-field inner ring monitoring holes 3 and four far-field outer ring monitoring holes 4 are arranged in a cross shape, a ring shape, or approximately equal angles along the circumference of the main test hole 1. The four near-field inner ring monitoring holes 3 and the four far-field outer ring monitoring holes 4 are radially corresponding to each other, forming a first radial monitoring zone 22, a second radial monitoring zone 23, a third radial monitoring zone 24, and a fourth radial monitoring zone 25.

[0034] In other embodiments, the near-field inner ring monitoring hole 3 and the far-field outer ring monitoring hole 4 can also be arranged at non-equiangular angles according to the direction of the maximum horizontal principal stress, the direction of the dominant joint and crack, the direction of the bedding, or the direction of the known weak structural surface.

[0035] Figure 4 The black dotted single arrow in the middle indicates the data flow direction. The inner acoustic emission sensor 5 and the outer acoustic emission sensor 6 are connected to the acoustic emission acquisition module 15; the outer surrounding rock stress sensor 7 and the outer pore air pressure sensor 8 are connected to the outer low-frequency acquisition module 16. Both the acoustic emission acquisition module 15 and the outer low-frequency acquisition module 16 are connected to the hardware synchronization module 17.

[0036] Hardware synchronization module 17 provides a unified time base to align acoustic emission, outer ring surrounding rock stress, outer ring pore air pressure, and loading pressure data in time. Edge controller 18 performs acoustic emission event identification, channel correction, zoning index calculation, and interlocking discrimination.

[0037] Figure 4The black double-headed dashed line in the middle indicates a bidirectional control connection, allowing for bidirectional signal transmission. PLC controller 19 is used to execute intake, pressure holding, and stepped pressure relief control, and records the rapid pressure relief status. Safety interlock circuit 20 operates independently of the host computer 21, directly outputting hardware interlock signals when extreme interlock conditions are met. Host computer 21 is used for setting test parameters, storing data, and displaying status.

[0038] III. Low-voltage preloading and channel calibration S2. Low-pressure preload calibration. This involves performing low-pressure preload calibration before formal airload loading to obtain the acoustic emission background baseline, acoustic emission propagation attenuation correction coefficient, channel confidence coefficient, gas flow noise characteristics, outer ring surrounding rock stress baseline, and outer ring pore pressure baseline for each radial monitoring zone. It also generates the first-level interlocking threshold, second-level interlocking threshold, and ultimate interlocking threshold. It is important to note the following in this step: Before the formal loading, the system performs a self-check of the equipment status. The self-check includes the pressure status of the high-pressure air source 9, the opening and closing status of each valve group, the zero-point status of the pressure sensor 14, the trigger status of the acoustic emission acquisition module 15, the communication status of the outer ring low-frequency acquisition module 16, the synchronization status of the hardware synchronization module 17, and the operation status of the safety interlock circuit 20.

[0039] After passing the self-test, perform low-pressure preloading calibration. The low-pressure preloading pressure is lower than the expected crack initiation pressure or the set safety pressure, so that the high-pressure radial loading unit 2 applies a low-level pressure to the borehole wall of the main test hole 1 that will not cause significant crack propagation.

[0040] 1. Propagation attenuation correction factor During the low-pressure preloading stage, standard pulse sources, artificial low-energy pulse sources, or repeatable low-energy sound sources are applied to the near-field inner monitoring hole 3, the far-field outer monitoring hole 4, or known locations of the adjacent rock mass, and the calibration response energy of each acoustic emission channel is collected.

[0041] Define the constraint function:

[0042] in, For dimensionless input values, and These are the dimensionless lower and upper limits, respectively, and satisfy the following conditions: .

[0043] No. The propagation attenuation correction factor for each acoustic emission channel is determined according to the following formula:

[0044] in, For the first The propagation attenuation correction coefficient for each acoustic emission channel is dimensionless. For the first The calibration response energy of each acoustic emission channel to the calibration sound source has the dimension of energy. The reference response energy has the dimension of energy. The reference response energy can be the median value of the calibration response energy of the qualified channel in the coupling state or the calibration response energy of the preset reference channel. To define the stable term, it has the dimension of energy to avoid the denominator being zero; and These are the preset lower and upper limits of the propagation attenuation correction coefficient, respectively. Both are dimensionless and satisfy the following conditions:

[0045] 2. Channel confidence coefficient No. The channel confidence coefficient of each acoustic emission channel is determined according to the following formula:

[0046] in, For the first The channel confidence coefficients for each acoustic emission channel are dimensionless and range from [value range missing]. ; , , , and The first The sensor coupling quality score, calibration response amplitude score, calibration response signal-to-noise ratio score, data integrity score, and positioning residual score for each acoustic emission channel are all dimensionless normalized scores and satisfy the following:

[0047] , , , and These are the dimensionless weighting coefficients for the corresponding scores, and they satisfy:

[0048] Let be the lower limit of the channel confidence coefficient, dimensionless, and satisfying the following:

[0049] If a certain acoustic emission channel experiences coupling failure, data loss, or positioning residual exceeding a preset upper limit, the channel confidence coefficient of that channel will be reduced, or the channel will be removed from the set of valid acoustic emission channels.

[0050] 3. Multi-channel parameter synthesis within a partition Record No. Each radial monitoring zone is located at The set of effective acoustic emission channels at that location is:

[0051] in, For a set, The number of valid acoustic emission channels contained in the set is a non-negative integer.

[0052] when and:

[0053] At that time, the first Each radial monitoring zone is located at The synthesis propagation attenuation correction factor at this point is:

[0054] in, It is a dimensionless quantity.

[0055] No. Each radial monitoring zone is located at The confidence coefficient of the synthesized channel at that point is:

[0056] in, It is a dimensionless quantity, and its range of values ​​is 1. .

[0057] when If the sum of the confidence coefficients of the effective channels is zero, the acoustic emission response at that position within the corresponding sliding time window is marked as invalid.

[0058] IV. Acoustic emission event identification and event weighting S3. Formal Air Loading, Synchronous Acquisition, and Event Weighting. Specifically, during the formal air loading process, using a sliding time window as the discrimination unit, this involves acquiring the loading pressure of the main test borehole, as well as the inner ring acoustic emission data, outer ring acoustic emission data, outer ring surrounding rock stress data, and outer ring pore air pressure data for each radial monitoring zone. Gas flow noise identification and event weighting are then applied to the acoustic emission events. It should be noted that the following points apply to this step: The edge controller 18 extracts one or more features from the acoustic emission waveform, including the main frequency, frequency band energy distribution, rise time, duration, ring count, average frequency, RA value, multi-channel arrival consistency, and spatial positioning residual.

[0059] For the first For each acoustic emission event, its RA value is defined as:

[0060] in, For the first The RA value of each acoustic emission event, with time / amplitude dimensions; For the first The rise time of the waveform of an acoustic emission event has the dimension of time. For the first The peak amplitude of each acoustic emission event waveform is expressed in the amplitude unit corresponding to the acoustic emission acquisition system.

[0061] Record No. The event weights of each acoustic emission event are: , It is a dimensionless quantity and satisfies:

[0062] When the When an acoustic emission event is determined to be a rock mass fracture acoustic emission event:

[0063] When the When an acoustic emission event is determined to be gas flow noise, gas jet noise, pipeline vibration noise, or electromagnetic interference noise:

[0064] When the When an acoustic emission event is determined to be a suspected mixed event:

[0065] V. Zonal Correction of Acoustic Emission Response and Zonal Radial Fracture Penetration Index S4. Generate zoning indicators and determine their validity. Specifically, this includes generating inner-circle corrected acoustic emission responses and outer-circle corrected acoustic emission responses based on weighted acoustic emission events, acoustic emission background baseline, acoustic emission propagation attenuation correction coefficient, and channel confidence coefficient. Based on the relative relationship between the inner-circle and outer-circle corrected acoustic emission responses, a zoning radial fracture penetration indicator is generated. A source radial migration indicator is generated based on the acoustic emission source location results. Finally, outer-circle surrounding rock stress changes and outer-circle pore gas pressure changes are generated. It should be noted that the following points apply to this step: Reference Figure 5 .

[0066] 1. Weighted acoustic emission statistics Record No. The radial monitoring zone in the first Within a sliding time window, at the position The set of acoustic emission events at the location is:

[0067] in, It is a set.

[0068] For any event Let its event energy be denoted as , It has the dimension of energy.

[0069] No. Each radial monitoring zone is located at The weighted acoustic emission energy release rate at the location is:

[0070] in, It has the dimensions of energy / time.

[0071] No. Each radial monitoring zone is located at The weighted acoustic emission event density at the location is:

[0072] in, It has the dimension of event count / time.

[0073] 2. Background statistics of acoustic emission In the low-pressure preloading stage Within a valid background sliding time window, the calculation is performed using the same method as the formal loading phase:

[0074] and:

[0075] in, The background-weighted acoustic emission energy release rate has the dimensions of energy / time. The background-weighted acoustic emission event density is expressed as the event number / time dimension.

[0076] The background energy release rate after propagation attenuation correction is:

[0077] in, It has the dimensions of energy / time.

[0078] The background mean and background standard deviation of energy release rate are as follows:

[0079]

[0080] in, and Both have the dimensions of energy / time.

[0081] The background mean and standard deviation of event density are as follows:

[0082]

[0083] in, and All of them have the dimension of event number / time.

[0084] 3. Correct the acoustic emission response. Define the nonnegativity function:

[0085] in, For dimensionless input quantities, This is a dimensionless output quantity.

[0086] No. Each radial monitoring zone is located at The corrected acoustic emission response at point is:

[0087] in, It is a dimensionless, non-negative quantity; The event density weighting coefficient is dimensionless. It is a stable term for energy release rate and has the dimensions of energy / time. It is a stable term for event density, and has the dimension of event number / time.

[0088] when At that time, This is denoted as the inner circle corrected acoustic emission response:

[0089] when At that time, This is denoted as the outer ring corrected acoustic emission response:

[0090] 4. Radial fracture penetration index of the zone No. The radial monitoring zone in the first The radial fracture penetration index within each sliding time window is:

[0091] in, It is a dimensionless quantity; This is a dimensionless stable term used to avoid the denominator being zero; satisfy:

[0092] When both the inner ring corrected acoustic emission response and the outer ring corrected acoustic emission response are zero:

[0093] When the proportion of the outer ring corrected acoustic emission response in the sum of the inner and outer ring corrected acoustic emission responses increases... An increase indicates a stronger trend in the expansion of fracturing activity from the near-field region of the main test well to the far-field outer control region.

[0094] When the acoustic emission response at any position on either the inner or outer ring is marked as invalid, the corresponding sliding time window is not calculated. The radial fracture penetration index of the partition is marked as invalid; invalid indices are not included in the number of indices that reach the interlocking threshold.

[0095] VI. Radial migration index of the seismic source like Figure 6 As shown, let the first... The radial monitoring zone in the first The set of valid positioning acoustic emission events within a sliding time window is:

[0096] in, It is a set.

[0097] For any event Let its spatial position vector be . Let the position vector of the center of the main test hole be . Both coordinate components have the dimension of length.

[0098] No. The radial monitoring zone in the first The weighted centroid of acoustic emission sources within a sliding time window is:

[0099] in, It is a position vector with the dimension of length.

[0100] The equivalent radial distance from the centroid of the acoustic emission source to the center of the main test borehole is:

[0101] in, It has the dimension of length; This represents the Euclidean distance norm.

[0102] No. The radial monitoring zone in the first The source radial migration index within each sliding time window is:

[0103] in, It is a dimensionless quantity and satisfies:

[0104] when When the value is small, it indicates that the acoustic emission source is mainly concentrated in the near-field inner circle region; when... When the value continues to increase, it indicates that the centroid of the acoustic emission source is migrating towards the far-field outer control region.

[0105] When the number of valid location acoustic emission events is less than the preset minimum number, or:

[0106] At that time, the corresponding sliding time window is not calculated. And mark the radial migration index of the seismic source as invalid.

[0107] VII. Changes in stress and pore pressure in the outer surrounding rock Record No. The radial monitoring zone in the first Within each sliding time window, the average stress of the outer surrounding rock after filtering is:

[0108] in, It possesses a force-response axis.

[0109] Record No. The radial monitoring zone in the first Within each sliding time window, the average outer pore air pressure after filtering is:

[0110] in, It has the dimension of pressure.

[0111] Record No. The average values ​​of the outer ring surrounding rock stress and the average values ​​of the outer ring pore gas pressure in the effective background sliding time window are as follows:

[0112] and:

[0113] Both have the dimensions of stress and pressure, respectively.

[0114] The baseline stress of the outer surrounding rock is:

[0115] The standard deviation of the background stress in the outer surrounding rock is:

[0116] in, and All of them possess a force-response axis.

[0117] The baseline for the outer pore pressure is:

[0118] The standard deviation of the background pore pressure in the outer ring is:

[0119] in, and All of them have the dimension of pressure.

[0120] The stress change in the outer surrounding rock is:

[0121] in, It possesses a force-response axis.

[0122] The change in pore pressure in the outer ring is:

[0123] in, It has the dimension of pressure.

[0124] 8. Three-level interlocking threshold Based on the background baseline data obtained in step S2, this embodiment further generates three-level interlocking thresholds corresponding to various indicators.

[0125] 1. Threshold for radial fracture penetration index in the partitioned area In the Within a valid background sliding time window, the radial fracture penetration index of the background partition is calculated using the same method as in the formal loading phase:

[0126] in, It is a dimensionless quantity.

[0127] The background mean and background standard deviation of the radial fracture penetration index for the zone are as follows:

[0128]

[0129] in, and All are dimensionless quantities.

[0130] set up The lower limit of the background standard deviation for the pre-defined radial fracture penetration index is dimensionless. The background standard deviation after lower limit correction is:

[0131] in, It is a dimensionless quantity.

[0132] Interlocking levels The threshold for radial fracture penetration index in the following partition is:

[0133] in, For the first Each radial monitoring zone at the interlocking level The penetration index threshold below is dimensionless; Interlocking level The corresponding penetration index threshold coefficient is dimensionless.

[0134] The threshold coefficients for each level of connectivity index should be selected such that:

[0135] 2. Threshold for radial migration index of seismic source Record No. The upper limit of radial positioning error obtained by each radial monitoring zone in the low-pressure preload positioning calibration is:

[0136] in, It has the dimension of length.

[0137] No. The normalized radial positioning error of each radial monitoring zone is:

[0138] in, It is a dimensionless quantity and satisfies:

[0139] The maximum normalized radial positioning error in all radial monitoring zones is:

[0140] in, It is a dimensionless quantity.

[0141] remember Interlocking level The corresponding basic migration level coefficient, It is a dimensionless quantity and satisfies:

[0142] Interlocking levels The threshold for the radial migration index of the seismic source is:

[0143] in, It is a dimensionless quantity and satisfies:

[0144] 3. Threshold for abnormal stress in the outer surrounding rock set up It is the lower limit of the preset standard deviation of the background stress of the outer ring surrounding rock, and has the stress dimension.

[0145] The standard deviation of the background stress in the outer ring surrounding rock, after lower limit correction, is:

[0146] in, It possesses a force-response axis.

[0147] Interlocking levels The threshold value for stress anomaly in the outer ring surrounding rock is:

[0148] in, It has a force axis; Interlocking level The corresponding dimensionless stress anomaly threshold coefficient, and satisfies:

[0149] 4. Outer pore pressure anomaly threshold set up It is the preset lower limit of the background standard deviation of the outer ring pore air pressure, and has the dimension of pressure.

[0150] The background standard deviation of the outer pore pressure after lower limit correction is:

[0151] in, It has the dimension of pressure.

[0152] Interlocking levels The outer pore pressure anomaly threshold is:

[0153] in, It has the dimension of pressure; Interlocking level The corresponding dimensionless pore pressure anomaly threshold coefficient, satisfying:

[0154] IX. Minimum Effective Increment During the low-pressure preloading phase, background samples of source radial migration indices for each radial monitoring zone were calculated. The sample is a dimensionless quantity.

[0155] The background standard deviation of the source radial migration index is:

[0156] in:

[0157] and All are dimensionless quantities.

[0158] The background standard deviation of the source radial migration index after lower limit correction is:

[0159] in, It is a dimensionless quantity.

[0160] Define the minimum effective increment for four types of indicators:

[0161] in, and It is a dimensionless quantity; It has a force axis; It has the dimension of pressure; , , and These are the dimensionless incremental discriminant coefficients for the penetration index, migration coefficient, stress change, and pore pressure change, respectively, and they satisfy the following:

[0162] 10. Stage Interlocking Judgment and Valve Group Control S5. Graded Interlocking Judgment. This involves comparing the radial fracture penetration index, source radial migration index, absolute values ​​of outer ring surrounding rock stress changes, and absolute values ​​of outer ring pore air pressure changes with the corresponding first-level interlocking threshold, second-level interlocking threshold, and ultimate interlocking threshold, respectively, to determine the interlocking status of each radial monitoring zone. It should be noted that: The system only counts the types of indicators with valid values ​​within each sliding time window. When there are fewer than two types of valid indicators in the same radial monitoring zone, the system stops increasing the pressure and enters a pressure holding check state or a controlled pressure release state.

[0163] 1. Level 1 Warning When the A radial monitoring zone is deemed to enter a Level 1 warning state when at least two of the following four conditions are met:

[0164] In the first-level warning state, the PLC controller 19 reduces the opening of the intake pressure regulating valve assembly 10, or reduces the pressure boosting rate to the originally set pressure boosting rate. times.

[0165] in, Let be a dimensionless rate-of-decrease factor, satisfying:

[0166] 2. Level II Warning When the A radial monitoring zone is deemed to have entered a Level II early warning state when at least two of the following four conditions are met:

[0167] In addition, set This refers to the minimum number of consecutive sliding time windows required to upgrade from a Level 1 warning to a Level 2 warning. It is a positive integer. When the Level 1 warning state is maintained for no less than [number] consecutive [durations], [the condition is considered valid]. If a radial monitoring zone enters a level-two warning state when there are multiple sliding time windows and at least one type of effective indicator shows an increment greater than the corresponding minimum effective increment within the most recent sliding time window relative to the previous sliding time window, the zone is also determined to have entered a level-two warning state.

[0168] In the second-level early warning state, the PLC controller 19 closes or reduces the opening of the intake pressure regulating valve group 10 and opens the pressure holding valve group 11 to keep the pressure of the main test port 1 near the current pressure and enter the pressure holding observation state.

[0169] 3. Pressure holding observation and step-by-step pressure relief set up The minimum number of consecutive sliding time windows required for the interlocking criterion to continuously deteriorate under pressure-holding observation conditions. It is a positive integer.

[0170] When the pressure in the main test port remains within the preset allowable fluctuation range, when the first... For each radial monitoring zone, at least two of the following four incremental conditions must be valid for a continuous period of time. When a sliding time window is established, the interlocking criterion for determining that the radial monitoring zone continues to deteriorate:

[0171]

[0172]

[0173]

[0174] in, For the first The end time of each sliding time window represents the previous decision time before the current decision time; when At that time, the incremental judgment of adjacent sliding time windows is not performed.

[0175] If the interlock criterion is determined to continue to deteriorate, the PLC controller 19 closes the intake pressure regulating valve group 10 and opens the stepped pressure relief valve group 12, so that the pressure of the main test port is reduced step by step according to the preset pressure drop rate or preset pressure drop step.

[0176] 4. Quickly relieve pressure S6. Valve assembly and hardware safety interlock control. Specifically, this includes controlling the intake pressure regulating valve assembly, pressure holding valve assembly, stepped pressure relief valve assembly, and rapid pressure relief valve assembly to perform normal loading, deceleration loading, pressure holding observation, stepped pressure relief, or rapid pressure relief based on the interlock status and the loading pressure of the main test port. It also triggers the corresponding control action when any radial monitoring zone reaches the corresponding interlock condition. It should be noted that: When the Each radial monitoring zone simultaneously satisfies:

[0177] and:

[0178] And it meets at least one of the following conditions:

[0179] or:

[0180] At that time, the system determines that the radial monitoring zone has entered a rapid depressurization trigger state.

[0181] At this time, the safety interlock circuit 20 directly outputs a hardware interlock signal. The hardware interlock signal has a higher priority than the ordinary control commands issued by the PLC controller 19 and the host computer 21. It forcibly closes the intake pressure regulating valve group 10 and opens the fast pressure relief valve group 13, so that the high pressure radial loading unit 2 can be depressurized quickly. The PLC controller 19 records the fast pressure relief trigger status and the valve group action status simultaneously.

[0182] XI. Overall Auxiliary Evaluation Indicators When it is necessary to evaluate the overall fracture propagation state of the surrounding rock around the main test well, record the first... The set of effective radial monitoring zone numbers for radial fracture penetration index within a sliding time window is as follows:

[0183] in, It is a set.

[0184] The number of valid partitions is:

[0185] in, It is a non-negative integer.

[0186] when:

[0187] At that time, the global radial fracture penetration index is:

[0188] in, For the first The global radial fracture penetration index within each sliding time window is a dimensionless quantity and satisfies:

[0189] when When this happens, the global radial fracture penetration index within the sliding time window is marked as invalid.

[0190] The global radial fracture penetration index is only used to assist in evaluating the overall fracture propagation state of the surrounding rock and does not replace the interlocking judgment of radial monitoring zones. When any radial monitoring zone reaches the level 2 warning state, the step-decompression state, or the rapid decompression state, regardless of the value of the global radial fracture penetration index, the system will perform pressure holding, step-decompression, or rapid decompression according to the judgment result of that dangerous zone.

[0191] XII. Other Implementation Methods This invention is not limited to four radial monitoring zones. The number of radial monitoring zones can be adjusted according to the diameter of the main test borehole, the surrounding rock structure, the direction of initial in-situ stress, the degree of joint and fracture development, and the on-site construction conditions.

[0192] This invention does not limit the use of a specific positioning algorithm for acoustic emission source localization. As long as the location of the acoustic emission source can be obtained based on the arrival time difference, waveform similarity or other positioning information of the same acoustic emission event collected by multiple acoustic emission sensors, it can be used to calculate the radial migration index of the source.

[0193] This invention does not require the inversion of the radial deformation field of the main test borehole wall or the inversion of the radius of the plastic zone of the surrounding rock as necessary control conditions. However, when the corresponding sensors and computing conditions are available, borehole wall displacement, permeability change or other surrounding rock response can be used as auxiliary monitoring quantities.

[0194] The threshold coefficient, sliding time window length, number of continuous time windows, pressure drop rate, and pressure drop step size that are not explicitly defined in the above embodiments can be determined based on the low-pressure preloading calibration results, on-site lithology, sensor accuracy, and test safety level.

Claims

1. A method for interlocking depressurization control of surrounding rock gas load in an underground high-pressure gas storage facility, characterized in that, Includes the following steps: S1. Arrange near-field inner ring monitoring holes and far-field outer ring monitoring holes around the main test hole from near to far. Form a radial monitoring zone by combining at least one near-field inner ring monitoring hole and at least one far-field outer ring monitoring hole located in the same radial monitoring profile, and use each radial monitoring zone as a monitoring data processing and interlocking discrimination unit. S2. Before the formal air load loading, perform low-pressure preload calibration to obtain the acoustic emission background baseline, acoustic emission propagation attenuation correction coefficient, channel confidence coefficient, gas flow noise characteristics, outer ring surrounding rock stress baseline and outer ring pore gas pressure baseline of each radial monitoring zone, and generate the first-level interlocking threshold, second-level interlocking threshold and ultimate interlocking threshold. S3. During the formal air load loading process, the sliding time window is used as the discrimination unit to obtain the loading pressure of the main test hole and the acoustic emission data of the inner ring, outer ring, outer ring surrounding rock stress and outer ring pore air pressure of each radial monitoring zone, and to identify gas flow noise and assign event weights to the acoustic emission events. S4. Based on the weighted acoustic emission events, the acoustic emission background baseline, the acoustic emission propagation attenuation correction coefficient, and the channel confidence coefficient, generate the inner circle corrected acoustic emission response and the outer circle corrected acoustic emission response. Generate the zonal radial fracture penetration index according to the relative relationship between the inner circle corrected acoustic emission response and the outer circle corrected acoustic emission response. Generate the source radial migration index based on the acoustic emission source location results. Generate the outer circle surrounding rock stress change and the outer circle pore gas pressure change. S5. The radial fracture penetration index of the zone, the radial migration index of the seismic source, the absolute value of the change in stress of the outer ring surrounding rock and the absolute value of the change in pore air pressure of the outer ring are compared with the corresponding first-level interlocking threshold, second-level interlocking threshold and ultimate interlocking threshold respectively to determine the interlocking status of each radial monitoring zone. S6. Based on the interlock status and the loading pressure of the main test hole, control the intake pressure regulating valve group, pressure holding valve group, stepped pressure relief valve group and rapid pressure relief valve group to perform normal loading, deceleration loading, pressure holding observation, stepped pressure relief or rapid pressure relief, and trigger the corresponding control action when any radial monitoring zone reaches the corresponding interlock condition.

2. The method for interlocking depressurization control of surrounding rock gas in underground high-pressure gas storage facilities according to claim 1, characterized in that, In step S1, four near-field inner ring monitoring holes and four far-field outer ring monitoring holes are arranged along the circumference of the main test hole. One near-field inner ring monitoring hole and one far-field outer ring monitoring hole located in the same design azimuth angle or the same radial monitoring profile are radially aligned to form four radial monitoring zones. The near-field inner ring monitoring holes and the far-field outer ring monitoring holes are arranged in a cross shape, a ring shape, or other angles, or are arranged at non-uniform angles according to the initial geostress direction, dominant joint fracture orientation, bedding direction, or weak structural plane direction of the test area.

3. The method for interlocking depressurization control of surrounding rock gas in underground high-pressure gas storage facilities according to claim 2, characterized in that, In step S2: Within a loading range below the expected crack initiation pressure or the set safety pressure, the high-pressure radial loading unit installed in the main test hole is subjected to low-pressure preloading at at least one pressure level. The background acoustic emission response of the inner and outer rings of each radial monitoring zone was collected, and the background mean of acoustic emission energy release rate, the background standard deviation of acoustic emission energy release rate, the background mean of acoustic emission event density, and the background standard deviation of acoustic emission event density were obtained for the inner and outer rings, respectively. Collect the outer ring surrounding rock stress stability response and outer ring pore air pressure stability response of each radial monitoring zone to obtain the outer ring surrounding rock stress baseline, outer ring pore air pressure baseline, outer ring surrounding rock stress fluctuation standard deviation and outer ring pore air pressure fluctuation standard deviation; Based on the known location of the pulse source, the acoustic emission response during the low-pressure preloading stage, or the acoustic wave propagation distance, determine the inner ring acoustic emission propagation attenuation correction coefficient and the outer ring acoustic emission propagation attenuation correction coefficient. The confidence coefficients of the inner and outer channels are determined based on one or more of the following: sensor coupling quality, calibration response amplitude, calibration response signal-to-noise ratio, background noise level, data integrity rate, and positioning residual. When there is no effective acoustic emission channel in the inner or outer ring of the same radial monitoring zone, or when the sum of the channel confidence coefficients of the corresponding effective acoustic emission channels is zero, the acoustic emission response at the corresponding location is marked as invalid.

4. The method for interlocking depressurization control of surrounding rock gas in an underground high-pressure gas storage facility according to claim 3, characterized in that, In step S3, the acoustic emission event is identified based on one or more of the following: dominant frequency, frequency band energy distribution, rise time, duration, ring count, average frequency, RA value, multi-channel arrival consistency, and spatial positioning residual; the RA value is the ratio of the rise time to the peak amplitude of the acoustic emission waveform. When the acoustic emission event is determined to be a rock mass fracture acoustic emission event, its event weight is set to 1; When the acoustic emission event is determined to be gas flow noise, gas jet noise, pipeline vibration noise, or electromagnetic interference noise, its event weight is set to 0. When the acoustic emission event is determined to be a suspected mixed event, its event weight is set to be greater than 0 and less than 1.

5. The method for interlocking depressurization control of surrounding rock gas load in underground high-pressure gas storage facilities according to claim 4, characterized in that, In step S4: Based on the weighted acoustic emission events in the inner and outer rings within each radial monitoring zone, the weighted acoustic emission energy release rate, the weighted acoustic emission energy release rate, the weighted acoustic emission event density, and the weighted acoustic emission event density in the inner and outer rings are obtained respectively. Based on the background mean, background standard deviation, background mean, and background standard deviation of acoustic emission energy release rate, obtained during the low-pressure preloading stage, the corresponding weighted acoustic emission energy release rate and weighted acoustic emission event density are normalized. Then, combined with the inner ring acoustic emission propagation attenuation correction coefficient, the outer ring acoustic emission propagation attenuation correction coefficient, the inner ring channel confidence coefficient, and the outer ring channel confidence coefficient, the inner ring corrected acoustic emission response and the outer ring corrected acoustic emission response are generated. The radial fracture penetration index of the partition is determined based on the proportion of the outer ring corrected acoustic emission response to the sum of the inner ring corrected acoustic emission response and the outer ring corrected acoustic emission response. When the acoustic emission response at any position of the inner or outer ring is marked as invalid, the radial fracture penetration index of the corresponding sliding time window is marked as invalid. The invalid index is not included in the number of indices that reach the interlocking threshold.

6. The method for interlocking depressurization control of surrounding rock gas load in underground high-pressure gas storage facilities according to claim 5, characterized in that, In step S4: The acoustic emission source is located by collecting the arrival time difference of the same acoustic emission event from multiple acoustic emission sensors. For each radial monitoring zone, within the corresponding sliding time window, the product of the event weight and the event energy of each effective location acoustic emission event is used as the weighting factor to determine the weighted centroid of the acoustic emission source. Based on the distance between the weighted centroid of the acoustic emission source and the center of the main test hole, the equivalent radial distance from the centroid of the acoustic emission source to the center of the main test hole is determined. The source radial migration index is generated based on the degree of change of the equivalent radial distance relative to the radial distance from the near-field inner ring monitoring hole to the center of the main test hole and the radial distance from the far-field outer ring monitoring hole to the center of the main test hole. When the number of valid location acoustic emission events within the corresponding sliding time window is lower than the preset minimum number, or when the sum of the product of the event weight and the event energy of each valid location acoustic emission event is zero, the source radial migration index within the corresponding sliding time window is marked as invalid. The source radial migration index marked as invalid is not included in the number of indices that reach the interlocking threshold.

7. The method for interlocking depressurization control of surrounding rock gas load in underground high-pressure gas storage facilities according to claim 6, characterized in that, In step S2: Based on the sample of radial fracture penetration index of the partition obtained by the same calculation method in the formal loading stage within multiple effective background sliding time windows in the low-pressure preloading stage or stable background stage, the background mean and background standard deviation of the radial fracture penetration index of the partition are statistically obtained, and the first-level penetration index threshold, the second-level penetration index threshold and the ultimate penetration index threshold are generated. Based on the upper limit of the radial positioning error of the acoustic emission source obtained through standard pulse source, known position sound source or positioning residual statistics during the low-pressure preloading stage, the normalized radial positioning error is determined, and based on the normalized radial positioning error and the preset first-level foundation migration level coefficient, second-level foundation migration level coefficient and ultimate foundation migration level coefficient, the first-level migration coefficient threshold, second-level migration coefficient threshold and ultimate migration coefficient threshold are generated. Based on the standard deviation of stress fluctuation in the outer surrounding rock, a first-level stress anomaly threshold, a second-level stress anomaly threshold, and a limit stress anomaly threshold are generated. Based on the standard deviation of the outer pore pressure fluctuation, a first-level pressure anomaly threshold, a second-level pressure anomaly threshold, and a limit pressure anomaly threshold are generated. Among the same type of interlocking thresholds, the first-level interlocking threshold is lower than the second-level interlocking threshold, and the second-level interlocking threshold is lower than the ultimate interlocking threshold.

8. The method for interlocking depressurization control of surrounding rock gas load in underground high-pressure gas storage facilities according to claim 7, characterized in that, The conditions for determining a valid index in steps S5 and S6 are that it can be calculated based on valid monitoring data within the corresponding sliding time window and is not marked as invalid: the zonal radial fracture penetration index, the source radial migration index, the absolute value of the change in stress of the outer ring surrounding rock, or the absolute value of the change in pore air pressure of the outer ring. When there are no fewer than two types of effective indicators in the same radial monitoring zone, when at least two of the following effective indicators reach the corresponding first-level interlocking threshold: the radial fracture penetration index of the zone, the radial migration index of the seismic source, the absolute value of the change in stress of the outer ring surrounding rock, and the absolute value of the change in pore air pressure of the outer ring, the radial monitoring zone is determined to enter the first-level early warning state, and the opening of the air intake pressure regulating valve group or the pressure rise rate of the main test hole is reduced. When at least two of the following effective indicators reach the corresponding secondary interlocking threshold: the radial fracture penetration index of the zone, the radial migration index of the seismic source, the absolute value of the change in stress of the outer ring surrounding rock, and the absolute value of the change in pore air pressure of the outer ring, the radial monitoring zone is determined to enter the secondary early warning state. Alternatively, when the first-level warning state is continuously maintained for no less than a preset number of sliding time windows, and the increment of at least one type of effective indicator between adjacent sliding time windows reaches the corresponding minimum effective increment, the radial monitoring zone is determined to enter the second-level warning state. In the secondary warning state, the opening of the intake pressure regulating valve group is closed or reduced, and the pressure of the main test port is maintained within a preset allowable fluctuation range based on the current pressure through the pressure holding valve group; When the effective indicators of the same radial monitoring zone are less than two types within the corresponding sliding time window, the pressure increase is stopped, and the main test hole is put into a pressure holding check state or a controlled pressure relief state.

9. The method for interlocking depressurization control of surrounding rock gas load in underground high-pressure gas storage according to claim 8, characterized in that, During the pressure holding observation process corresponding to the Level 2 warning state: When the pressure of the main test hole remains within the preset allowable fluctuation range, and at least two of the following effective indicators in the same radial monitoring zone—the radial fracture penetration index, the radial migration index of the seismic source, the absolute value of the change in stress of the outer ring surrounding rock, and the absolute value of the change in pore air pressure of the outer ring—have reached the corresponding minimum effective increment relative to the end of their respective previous sliding time window, and the state in which the at least two effective indicators have reached the corresponding minimum effective increment is not less than a preset number of sliding time windows, it is determined that the interlocking criterion of the radial monitoring zone continues to deteriorate. Close the intake pressure regulating valve group and open the stepped pressure relief valve group to reduce the pressure of the main test port stepwise according to the preset pressure drop rate or preset pressure drop step. The radial fracture penetration index of the partition, the radial migration index of the seismic source, the absolute value of the change in stress of the outer ring surrounding rock, and the absolute value of the change in pore air pressure of the outer ring are respectively used as incremental comparison quantities based on the difference between the current sliding time window and the previous sliding time window. The minimum effective increment is determined based on the background standard deviation, radial positioning error, or background fluctuation amplitude of the corresponding indicators in the low-pressure preloading stage.

10. The method for interlocking depressurization control of surrounding rock gas load in underground high-pressure gas storage facilities according to claim 9, characterized in that: When the radial fracture penetration index and the source radial migration index of the same radial monitoring zone both reach the corresponding limit interlocking threshold, and at least one of the absolute values ​​of the change in stress of the outer ring surrounding rock or the absolute value of the change in pore air pressure of the outer ring reaches the corresponding limit interlocking threshold, the radial monitoring zone is determined to enter the rapid decompression triggering state. Trigger a safety interlock circuit that operates independently of the host computer. The safety interlock circuit directly outputs a hardware interlock signal to forcibly close the intake pressure regulating valve group and open the rapid pressure relief valve group, so that the high-pressure radial loading unit can be depressurized quickly. The hardware interlock signal has a higher priority than the ordinary control commands issued by the PLC controller and the host computer.

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