A coal mine roof hydraulic fracturing safety energy absorption device and method

Abstract

The present application relates to the field of mining engineering, specifically to a coal mine roof hydraulic fracturing safety energy absorption device and method; the method comprises the following steps: obtaining energy input data and energy release data in a preset time period; time period level corresponding the energy input data and the energy release data, obtaining energy absorption response data, and judging whether the change amplitude of the ratio between the energy input data and the energy release data exceeds a preset threshold value, if yes, obtaining the energy absorption state evolution interval, and obtaining the corresponding energy absorption state interval identifier; dynamically switching the fracturing process control state of different energy absorption state evolution intervals, and adjusting the pressure change amplitude and the flow rate change rate of the hydraulic fracturing process when detecting that the ratio relationship between the energy input data and the energy release data changes. The present application can realize dynamic identification and safety control of energy absorption behavior in the hydraulic fracturing process, and improve the roof stability and operation safety.

Description

Technical Field

[0001] This invention relates to the field of mining engineering, specifically to a safe energy-absorbing device and method for hydraulic fracturing of coal mine roof. Background Technology

[0002] Due to the concentration of in-situ stress and the complex structure of the surrounding rock in coal mine roof areas, roof failure and rockbursts are easily induced during enhanced ventilation, pressure control, or gas extraction modifications such as hydraulic fracturing, posing a serious threat to operational safety. To improve the stability and energy regulation capabilities of the roof rock mass, hydraulic fracturing is widely used as a common induced release technology. This technology injects high-pressure fluid into the roof strata, inducing fracture propagation and energy release, thereby achieving pressure reduction and improved permeability. During fracturing, the dynamic relationship between the input energy and the released energy reflects the energy absorption characteristics of the coal and rock mass, serving as a crucial parameter for ensuring the safety of the fracturing process.

[0003] In existing technologies, hydraulic fracturing methods for coal mine roofs mainly focus on crack formation and stress release, failing to recognize the nonlinear changes in energy absorption efficiency during crack evolution. This leads to the continued injection of water after the cracks enter an inefficient energy absorption stage, resulting in excessive weakening of the roof structure or unstable safe energy absorption performance, which is a problem we need to solve. Summary of the Invention

[0004] The purpose of this application is to provide a safe energy absorption method for hydraulic fracturing of coal mine roof, which has the advantages of realizing synchronous analysis of multi-source energy data and dynamic energy absorption status identification during hydraulic fracturing, timely reflecting the matching relationship of energy transfer and dissipation at different fracturing stages, thereby improving the safety assessment capability and response control accuracy during the fracturing process of roof rock strata.

[0005] The objective of this application can be achieved through the following technical solution: Firstly, a safe energy absorption method for hydraulic fracturing of coal mine roof, comprising the following steps:

[0006] The energy input and energy release data of the target coal mine roof area are obtained after preprocessing within a preset time period; the energy input data and energy release data are correlated at the time period level to obtain the energy absorption response data of the hydraulic fracturing process;

[0007] Based on the energy absorption response data, it is determined whether the change in the ratio between the energy input data and the energy release data within a preset time period exceeds a preset threshold. If so, the corresponding energy absorption state evolution interval is obtained, and the corresponding energy absorption state interval identifier is obtained based on the change analysis of the energy absorption state evolution interval.

[0008] Based on the energy absorption state interval identifier, the evolution intervals of different energy absorption states during hydraulic fracturing are dynamically switched. When a change in the ratio between energy input data and energy release data is detected, the time distribution structure of the hydraulic fracturing process is adjusted based on the current energy absorption state interval identifier to restore it to the preset stable interval.

[0009] Determine whether the energy absorption state interval identifier of the energy absorption state evolution interval belongs to the preset stability identifier. If so, extract the energy absorption response data of the corresponding time period for the energy absorption state evolution interval and analyze it to complete the safe energy absorption process.

[0010] Secondly, a safety energy-absorbing device for hydraulic fracturing of coal mine roof includes the following modules:

[0011] An energy identification module is used to acquire pre-processed energy input data and energy release data of the roof area of ​​a target coal mine within a preset time period; and to perform time-level correspondence between the energy input data and the energy release data to obtain energy absorption response data of the hydraulic fracturing process.

[0012] The state analysis module is used to determine, based on the energy absorption response data, whether the change in the ratio between the energy input data and the energy release data within a preset time period exceeds a preset threshold. If so, the continuous time period in which the change exceeds the preset threshold is defined as an energy absorption state evolution interval, and the corresponding energy absorption state interval identifier is obtained.

[0013] The hydraulic control response module is used to dynamically switch the fracturing process control state of different energy absorption state evolution intervals during hydraulic fracturing based on the energy absorption state interval identifier. When a change in the ratio between energy input data and energy release data is detected, the module adjusts the pressure change amplitude and flow rate of the hydraulic fracturing process based on the current energy absorption state interval identifier to restore the energy absorption state evolution interval of the current time period to a preset stable interval. The preset stable interval is the interval in which the energy absorption state interval identifier indicates that the hydraulic fracturing process is safe.

[0014] Thirdly, a computer storage medium storing computer-executable instructions, which, when executed, implement the safe energy absorption method for hydraulic fracturing of coal mine roof as described in the first aspect.

[0015] Compared with the prior art, the beneficial effects of this application are:

[0016] This invention constructs an energy absorption response mechanism based on the ratio of energy input data to energy release data, achieving precise identification and marking of the energy absorption state evolution interval during hydraulic fracturing of the roof. This solves the problems of existing technologies that rely on single microseismic counting or manual experience for judgment, and lack data support and dynamic control capabilities in the fracturing process. By coupling the energy absorption state interval marking with the fracturing process control strategy, when a change in the energy ratio is detected, the magnitude of the water injection pressure change and the rate of flow change can be adjusted in conjunction with the current energy absorption state, bringing the current fracturing process closer to the steady-state energy absorption interval. This effectively prevents the risk of roof instability caused by abnormal energy accumulation and release in the rock strata.

[0017] This invention introduces an energy absorption range attribute assignment and state transition judgment mechanism, which makes the energy input and release behavior at each stage of the fracturing process quantifiable, visible and controllable, improving the refined management capability of fracturing operations; at the same time, it sets a steady range and termination state judgment mechanism to realize adaptive closed-loop control of the entire fracturing process, avoid over-pressure operation and ineffective operation, and improve safety and operation efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the steps of a safe energy absorption method for hydraulic fracturing of the coal mine roof according to this application;

[0019] Figure 2 This is a schematic diagram of a safety energy-absorbing device for hydraulic fracturing of coal mine roof according to this application. Detailed Implementation

[0020] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0021] Application Overview:

[0022] In hydraulic fracturing operations in coal mine roof areas, due to factors such as stress concentration, structural complexity, and dynamic disturbances during fracturing, the coal and rock mass exhibits nonlinear, staged, and unstable energy absorption response characteristics during fracture evolution. However, current fracturing control technologies primarily focus on fracture propagation or stress release as the main control indicators, neglecting the dynamic changes in the energy absorption ratio between energy input and release during fracture evolution, and lacking identification and response control mechanisms for different energy absorption stages. Especially during inefficient energy absorption or excessive energy consumption stages, it is often impossible to adjust injection parameters in a timely manner, leading to roof structural weakening, energy absorption instability, and even inducing rockbursts and other disasters, seriously affecting operational safety and coal and rock mass stability.

[0023] For example, in a roof gas extraction and renovation project, data on rock mass energy release during fracturing was acquired using a microseismic monitoring device, along with simultaneous acquisition of water injection pressure and flow rate sequences. Analysis revealed that within a predetermined time period, the input energy continuously increased while the released energy increased slowly, resulting in a sharp rise in their ratio. However, because the traditional fracturing system lacked an energy absorption state identification mechanism, the original water injection strategy continued to be implemented. This led to a rapid decline in the roof rock mass's bearing capacity, subsequently triggering a high-intensity microseismic event. The fracturing operation needed to be urgently halted, and the support reinforcement reinforced, delaying the construction progress and posing significant safety risks.

[0024] Without addressing the aforementioned issues of missing energy absorption state identification and control response, efficient, safe, and controllable energy release management will be difficult to achieve during hydraulic fracturing of the coal mine roof. On one hand, an imbalance between energy input and release will lead to uncontrollable rock mass damage and an increased probability of rockbursts. On the other hand, the lack of energy absorption zone identification will result in resource waste and decision-making biases, limiting the engineering adaptability and safety of hydraulic fracturing in complex coal mine areas. This will force on-site operations to still rely heavily on manual experience and judgment, hindering the large-scale application and risk-controlled development of automated fracturing technology.

[0025] Therefore, this application provides a safe energy absorption method for hydraulic fracturing of the coal mine roof, such as... Figure 1 As shown, it includes the following steps:

[0026] The energy input and energy release data of the target coal mine roof area are obtained after preprocessing within a preset time period; the energy input data and energy release data are correlated at the time period level to obtain the energy absorption response data of the hydraulic fracturing process;

[0027] Based on the energy absorption response data, it is determined whether the change in the ratio between the energy input data and the energy release data within a preset time period exceeds a preset threshold. If so, the corresponding energy absorption state evolution interval is obtained, and the corresponding energy absorption state interval identifier is obtained based on the change analysis of the energy absorption state evolution interval.

[0028] Based on the energy absorption state interval identifier, the evolution intervals of different energy absorption states during hydraulic fracturing are dynamically switched. When a change in the ratio between energy input data and energy release data is detected, the time distribution structure of the hydraulic fracturing process is adjusted based on the current energy absorption state interval identifier to restore it to the preset stable interval.

[0029] Determine whether the energy absorption state interval identifier of the energy absorption state evolution interval belongs to the preset stability identifier. If so, extract the energy absorption response data of the corresponding time period for the energy absorption state evolution interval and analyze it to complete the safe energy absorption process.

[0030] This embodiment provides a safe energy absorption method for hydraulic fracturing of coal mine roofs. This method dynamically identifies the evolution of energy absorption behavior during hydraulic fracturing of coal mine roofs and adaptively adjusts fracturing control, thereby effectively improving roof stability and the safety of fracturing operations. Specifically, it includes the following steps:

[0031] First, acquire fracturing operation data of the target coal mine roof area within a preset time period, including energy input data (such as energy input per unit time during high-pressure water injection) and energy release data (such as energy released during fracture propagation) obtained through on-site pressure, flow and other monitoring sensors after preprocessing.

[0032] Next, the energy input data and energy release data are correlated according to the same time period to construct a time-based energy absorption response dataset. This dataset reflects the coal body's response to energy input and its dissipation efficiency throughout the hydraulic fracturing process, ensuring that the dynamic changes in energy absorption behavior can be tracked within the actual operational timescale.

[0033] Based on the energy absorption response data, the changing trend of the ratio between energy input and release (i.e., energy absorption efficiency) over different time periods is further analyzed to determine whether the change exceeds a preset threshold. If a significant change is detected (i.e., drastic local changes or energy absorption imbalance), it is considered that there may be abnormal fracturing behavior in the current time period, such as excessively rapid crack propagation or local energy accumulation, which poses a safety hazard. In this case, the time period with significant continuous changes is identified as an energy absorption state evolution interval.

[0034] Subsequently, based on the evolution range of the energy absorption state, and combined with indicators such as its change pattern, trend characteristics, and ratio fluctuation trajectory, an energy absorption state range identifier corresponding to this range is generated. This identifier is used to represent the risk level, evolution trend, and stability characteristics of the coal body's energy absorption behavior within this range, supporting the system's automatic identification and recording of different energy absorption states.

[0035] As the fracturing process continues, real-time data streams will be continuously monitored, and the fracturing process control state will be dynamically switched between each energy absorption evolution interval based on the current energy absorption state interval marker. If the current state is marked as unsteady, the system will adjust key hydraulic fracturing control parameters, mainly including the magnitude of injection pressure changes and the rate of flow rate changes, thereby guiding the current state back to a preset steady-state interval. This steady-state interval represents a balance between energy absorption and release in the coal seam fractures, which helps reduce the risk of sudden fracturing changes.

[0036] Furthermore, the system determines whether the current energy absorption state interval identifier is a preset set of stable identifiers (such as "steady state I interval", "dissipation balance interval", etc.). If it is determined to be a stable identifier, the system performs in-depth analysis on the energy absorption response data of the corresponding time period of the energy absorption state evolution interval, extracts typical energy absorption behavior characteristics, archives them as safe energy absorption processes, and uses them as experience samples for subsequent fracturing strategy parameter optimization.

[0037] This application proposes a process for obtaining pre-processed energy input and energy release data of the roof region of a target coal mine within a preset time period; and for mapping the energy input and energy release data at the time period level to obtain the energy absorption response data of the hydraulic fracturing process, including:

[0038] First, by conducting geological modeling and on-site investigation of the coal mine, rock structure data of the coal mine roof is obtained, including rock mechanical parameters, rock bedding distribution information (such as rock thickness, dip angle, interlayer location, etc.), in-situ stress data, and fracturing hole layout information.

[0039] During hydraulic fracturing operations, the injection pressure data, injection flow rate data, and microseismic event energy data are collected synchronously during the hydraulic fracturing process. The injection pressure data is a sequence of instantaneous injection pressure values ​​collected by pressure monitoring sensors at a preset sampling frequency during the hydraulic fracturing process, including the injection pressure value and the corresponding timestamp. The injection flow rate data is a sequence of instantaneous injection flow rate values ​​collected synchronously by flow meters at the same sampling frequency as the injection pressure data, including the injection flow rate value and the corresponding timestamp.

[0040] In terms of microseismic monitoring, multiple microseismic monitoring devices are uniformly deployed within the top slab of the target area. The microseismic signals collected by the microseismic monitoring devices are processed by the event recognition algorithm and energy inversion processing module of the ground server to obtain the corresponding microseismic event energy data, including the occurrence time of each microseismic event (e.g., in milliseconds) and the energy release value of the corresponding event.

[0041] To achieve unified data processing, rock strata structure data, water injection pressure data, water injection flow rate data, and microseismic event energy data were standardized and preprocessed based on the time axis, and a unified sampling time baseline was established. Linear interpolation, nearest neighbor imputation, or null value processing were used to ensure that each data point formed a corresponding synchronous sampling point within each preset time step (e.g., 5 seconds), thereby constructing a time-aligned multi-source synchronous dataset. Each time period contains corresponding rock strata structure data, water injection pressure data, water injection flow rate data, and microseismic event energy data.

[0042] Based on the multi-source synchronous dataset, the water injection pressure data and the water injection flow rate data are divided into time periods. and Δt represents the start and end times of adjacent time periods, and Δt represents the sampling interval. This processing procedure completes an integral approximate estimation of the instantaneous injected power within each segment, obtaining the energy input data for each segment.

[0043] Microseismic events within the same time period are summarized and statistically analyzed. The energy values ​​of all microseismic events occurring within this period are accumulated to obtain the corresponding energy release data for that period. The energy input data and energy release data within each time period are mapped to form a set of energy absorption response data indexed by time period. Each energy absorption response data contains corresponding values ​​of energy input and energy release. The energy absorption response data reflects the dynamic relationship between injected and released energy in different time periods, and can serve as the basis for subsequent identification of energy absorption state intervals, evolution characteristic intervals, and control of fracturing strategies. By mapping the energy input and energy release data in the hydraulic fracturing process in the roof region to time periods and constructing an energy absorption response data structure, physical modeling and dynamic identification of roof fracture initiation behavior are achieved. This not only significantly improves the visualization and accurate identification of the energy state in the fracturing process, but also provides highly consistent data support for subsequent stability state judgment and process termination control.

[0044] This application proposes a process for determining, based on the energy absorption response data, whether the change in the ratio between the energy input data and the energy release data exceeds a preset threshold within a preset time period. If so, the continuous time period in which the change exceeds the preset threshold is defined as an energy absorption state evolution interval, and the corresponding energy absorption state interval identifier is obtained. The process includes:

[0045] The energy input and energy release data for each time period are compared to obtain the energy absorption ratio sequence for that time period.

[0046] ;

[0047] in, This represents the energy released due to the accumulation of microseismic events during the i-th time period; This represents the input energy calculated from the injection pressure and injection flow rate during the i-th time period; This represents the energy absorption ratio for the i-th time period.

[0048] By performing difference calculations between adjacent time periods on the energy absorption ratio sequence, a sequence of energy absorption ratio variation amplitudes is obtained:

[0049] ;

[0050] in, This represents the energy absorption ratio during the (i-1)th time period. This is used to characterize the fluctuation of energy absorption behavior within adjacent time periods. Next, the change amplitude of each time period in the sequence of energy absorption ratio changes is compared with a preset threshold. A comparison was made one by one.

[0051] When the following conditions are met:

[0052] ;

[0053] Then it is determined that the energy absorption state has changed significantly within this time period. The preset threshold... The threshold can be set based on historical fracturing data or engineering experience, for example, 0.15 to 0.30 can be used as the judgment threshold to avoid misjudging small fluctuations.

[0054] After determining the energy absorption state evolution range, the system further aggregates and classifies the data within the range to generate corresponding energy absorption state range identifiers.

[0055] First, the energy input and energy release data corresponding to each time period within the energy absorption state evolution interval are aggregated and calculated to obtain interval-level energy absorption response data. For example, the mean, maximum, minimum, and fluctuation amplitude of the energy absorption ratio within the interval can be calculated to form an interval-level energy absorption response feature vector.

[0056] ;

[0057] in, This represents the average value of the energy absorption ratio within the interval; These are the ratios of the maximum and minimum energy absorption, respectively. This represents the standard deviation of the energy absorption ratio, used to characterize the degree of fluctuation.

[0058] Subsequently, time-series trend analysis was performed on the interval-level energy absorption response data, and it was matched against a preset set of state classification thresholds. The set of state classification thresholds can be preset, for example:

[0059] when Belongs to [0.8, 1.2] and When the value is less than the first fluctuation threshold, it is determined to be in a "stable energy absorption state";

[0060] when Continued decline and When the value exceeds the second fluctuation threshold, it is determined to be an "energy release mutation state";

[0061] when When the energy level continues to rise and the release of energy is significantly delayed, it is determined to be an "energy accumulation state".

[0062] After determining the state category, a unique state code is assigned to each energy-absorbing state category, such as a numerical or enumerated coding method (e.g., W1, W2, W3). A one-to-one correspondence is established between the energy-absorbing state category and the state code, ultimately generating an energy-absorbing state interval identifier for that energy-absorbing state evolution interval. By dynamically monitoring and judging the change amplitude of the "energy input to release ratio" in the energy-absorbing response data, the true coupling relationship of the energy-absorbing process is identified. This effectively reveals abnormal trends in energy excitation efficiency and constructs an energy-absorbing state evolution interval identifier, providing data support for subsequent staged fracturing control, thereby improving the accuracy and stability of fracturing operations.

[0063] This application proposes a method for dynamically switching the fracturing process control state across different energy absorption state evolution intervals during hydraulic fracturing based on the energy absorption state interval identifier. Furthermore, when a change in the ratio between energy input data and energy release data is detected, the pressure change amplitude and flow rate change rate of the hydraulic fracturing process are adjusted based on the current energy absorption state interval identifier to restore the energy absorption state evolution interval of the current time period to a preset stable interval. The preset stable interval is the interval indicated by the energy absorption state interval identifier as indicating a safe hydraulic fracturing process. The process includes:

[0064] During the continuous hydraulic fracturing process, a preset time period is used as the basic scheduling cycle. The energy absorption state interval identifier corresponding to the current time period is obtained in real time. A one-to-one correspondence is pre-established between the energy absorption state interval identifier and the preset fracturing process control state, for example:

[0065] Energy absorption state interval marker W1 → Conventional fracturing process control state;

[0066] Energy absorption state interval marker W2 → Slow-release fracturing process control state;

[0067] Energy absorption state interval identifier W3 → Energy absorption protection process control status.

[0068] Based on the energy absorption state interval identifier obtained in the current time period, the corresponding hydraulic fracturing process control state is retrieved, and the hydraulic fracturing process is scheduled and controlled at the process level according to the corresponding relationship. This dynamic switching process does not change the fracturing hardware structure, but only changes the control logic and scheduling state of the fracturing process, ensuring that the fracturing process can adaptively adjust with changes in energy absorption state.

[0069] During the fracturing process, the system continuously analyzes the changing ratio between energy input and energy release data in adjacent time periods. The energy absorption ratio for the i-th time period is: ;

[0070] When the following process switching trigger conditions are met:

[0071] ;

[0072] in, If a significant fluctuation occurs in the current energy absorption state, the current hydraulic fracturing process control state is switched to the control state corresponding to the preset energy absorption protection process, and a corresponding energy absorption protection trigger identifier is generated. The energy absorption protection trigger identifier is used to mark the starting time point of entering the energy absorption protection process and serves as the benchmark for subsequent time interval splitting and parameter adjustment.

[0073] After the energy absorption protection process is initiated, in order to achieve fine control and dynamic adjustment of the energy absorption state fluctuations in the hydraulic fracturing process, firstly, based on the energy absorption state interval identifier corresponding to the current fracturing stage, the water injection pressure data and water injection flow rate data within the time period covered by the corresponding energy absorption state interval are extracted from the multi-source data that have been collected simultaneously, and a set of continuous time series is generated, which is recorded as continuous water injection time interval data.

[0074] Specifically, let the energy absorption state interval be labeled S_now, and its start and end times be [ , If the time interval is extracted, then the time interval is extracted. , Construct a water injection pressure sequence using all pressure data within the specified range. Simultaneously extract the injection flow rate data at the corresponding time points to construct an injection flow rate sequence. The water injection pressure sequence With water injection flow sequence Combined to form complete continuous water injection time interval data The continuous water injection time interval data represents the set of pressure and flow time series data during the continuous water injection state of the hydraulic fracturing process before process switching.

[0075] Subsequently, taking the time point corresponding to the energy absorption protection trigger identifier as the dividing line, the energy absorption protection trigger identifier includes a trigger timestamp. And the corresponding abnormal energy absorption ratio fluctuation information.

[0076] when lie in[ , When the interval is within a certain range, the continuous water injection time interval data is divided into two segments based on the trigger point:

[0077] Previous interval data (i.e., before triggering):

[0078] ;

[0079] Data after the interval (i.e., after triggering):

[0080] ;

[0081] The continuous water injection time interval data is split into multiple time sub-intervals. For example, the water injection process before and after the trigger point can be divided into several sub-time periods of equal length or length set according to process requirements, for fine-grained analysis of pressure and flow change characteristics.

[0082] For each time sub-interval Calculate the corresponding pressure change amplitude and flow rate change rate, respectively. The pressure change amplitude can be expressed as:

[0083] ;

[0084] in, This represents all water injection pressure values ​​within the sub-interval;

[0085] The rate of change of flow can be expressed as:

[0086] ;

[0087] in, , The flow rate values ​​at the start and end times of the j-th sampling point within each sub-interval;

[0088] The duration of the sub-interval.

[0089] Voltage regulation range conditions: Preset set of voltage regulation thresholds (For example, ), (For example, ); Control parameters during voltage stabilization stage and .

[0090] Slow-release interval conditions: Preset set of voltage regulation thresholds (For example, ), (For example, ); Control parameters for the sustained-release phase and .

[0091] Based on the magnitude of pressure change and the rate of flow change, the interval attributes of each time sub-interval are determined:

[0092] when and When this sub-interval is determined to be a voltage stabilization interval, a voltage stabilization interval identifier is generated;

[0093] when or When the trend of change meets the conditions for slow release, the sub-interval is determined to be a slow release interval, and a slow release interval identifier is generated.

[0094] Based on the pressure stabilization zone identifier or the slow-release zone identifier, the data time stamp of the original water injection pressure and flow rate sequence is adjusted so that it matches the target water injection control strategy of each sub-zone in time sequence.

[0095] If the original water injection data contains parameters that do not conform to the interval attributes (such as a high flow rate segment within the slow-release interval), the rearrangement logic will be automatically triggered:

[0096] Identify sections within the release range that exceed the target flow rate, perform data backtracking, and re-plan the target pressure and flow rate pair;

[0097] Abrupt points during interpolation correction are identified to ensure smooth transitions within segments.

[0098] A new sequence of execution instructions is generated from the corrected parameters, including specific timestamps, target pressure values, target flow rates, etc., so that each sub-time period corresponds to the water injection control parameters of the pressure stabilization phase or the slow release phase. For example, in the pressure stabilization zone, the pressure and flow rate are kept basically constant, while in the slow release zone, the rate of change of flow rate or the magnitude of change of pressure are gradually reduced, thereby suppressing drastic fluctuations in the energy absorption state.

[0099] During the continuous hydraulic fracturing process, the system uses a preset time period (e.g., 60 seconds) as the judgment cycle to obtain the energy absorption state evolution interval identifier corresponding to the current fracturing time period in real time. The energy absorption state evolution interval identifier is a state code generated based on interval-level energy absorption response data in the aforementioned embodiment, used to characterize the coupling state of energy input and energy release within the current time period.

[0100] For example, in the current time period The energy absorption state evolution interval identifier obtained within can be represented as:

[0101] ;

[0102] Different identifiers correspond to different energy absorption state categories.

[0103] A pre-defined set of state identifiers corresponding to a stable state range is used to characterize the state range where the energy absorption behavior during hydraulic fracturing is within a safe and controllable range. For example:

[0104] ;

[0105] Among them, status identifier This indicates an energy absorption state where the interval-level energy absorption ratio is within a stable range, the energy absorption fluctuation amplitude is below the safety threshold, and no abnormal concentrated energy release behavior is detected.

[0106] The preset stable state interval identifier set can be set based on historical fracturing project data, field experience, or safety regulations, and loaded into the system before the fracturing operation begins.

[0107] After obtaining the energy absorption state evolution interval identifier corresponding to the current time period, the energy absorption state evolution interval identifier is... The set of state identifiers corresponding to the preset stable state interval The comparison process is performed to generate a stable state judgment result.

[0108] Specifically, the judgment rule is as follows:

[0109] StableFlag= ;

[0110] StableFlag=1 indicates that the current energy absorption state evolution range has entered the preset stable state range, while StableFlag=0 indicates that the current energy absorption state is still unstable.

[0111] To avoid misjudgments caused by instantaneous fluctuations, a continuous determination mechanism can be introduced. For example, it can be confirmed that the stable energy absorption state has been entered only if StableFlag=1 is satisfied for N consecutive time periods. N can be 2 to 5 time periods.

[0112] When the stable state judgment result indicates that the energy absorption state interval identifier of the current energy absorption state evolution interval is in the preset stable state interval, it is determined that the current hydraulic fracturing process has entered a stable energy absorption state, indicating that the energy input and energy release are in a controllable and balanced state interval.

[0113] After the determination result is valid, the hydraulic fracturing termination control process is executed, including but not limited to: generating a fracturing termination identifier and recording the corresponding timestamp; gradually reducing the injection flow rate and injection pressure according to the preset termination strategy to avoid system disturbance caused by sudden stop; stopping the energy input scheduling of subsequent fracturing stages, at which point the current hydraulic fracturing process ends.

[0114] Through the above embodiments, the present invention realizes dynamic switching and energy absorption protection of hydraulic fracturing process based on energy absorption state interval identification, enabling the fracturing process to adaptively adjust when energy absorption anomalies occur, and safely terminate the fracturing operation after the energy absorption state recovers to a stable range, thereby significantly improving the safety and controllability of hydraulic fracturing process of coal mine roof.

[0115] In another embodiment, this application also provides a safety energy-absorbing device for hydraulic fracturing of coal mine roof, such as... Figure 2 As shown, it includes the following modules:

[0116] An energy identification module is used to acquire pre-processed energy input data and energy release data of the roof area of ​​a target coal mine within a preset time period; and to perform time-level correspondence between the energy input data and the energy release data to obtain energy absorption response data of the hydraulic fracturing process.

[0117] The state analysis module is used to determine, based on the energy absorption response data, whether the change in the ratio between the energy input data and the energy release data within a preset time period exceeds a preset threshold. If so, the continuous time period in which the change exceeds the preset threshold is defined as an energy absorption state evolution interval, and the corresponding energy absorption state interval identifier is obtained.

[0118] The hydraulic control response module is used to dynamically switch the fracturing process control state of different energy absorption state evolution intervals during hydraulic fracturing based on the energy absorption state interval identifier. When a change in the ratio between energy input data and energy release data is detected, the module adjusts the pressure change amplitude and flow rate of the hydraulic fracturing process based on the current energy absorption state interval identifier to restore the energy absorption state evolution interval of the current time period to a preset stable interval. The preset stable interval is the interval in which the energy absorption state interval identifier indicates that the hydraulic fracturing process is safe.

[0119] This method uses an energy identification module to uniformly acquire and correspond energy input and energy release data during hydraulic fracturing of the coal mine roof to a time period, and constructs an energy absorption response data structure. This allows for the quantitative expression of the coupling relationship between injected energy and released energy from the rock strata during fracturing, avoiding the one-sidedness and lag caused by relying solely on a single pressure parameter or the number of microseismic events in existing technologies.

[0120] By dynamically analyzing the energy ratio variation amplitude in the energy absorption response data through the state analysis module, this method can identify continuous time periods in which the energy absorption state changes significantly and determine them as the energy absorption state evolution intervals. At the same time, it generates corresponding energy absorption state interval identifiers, thereby realizing the staged and structured characterization of the energy absorption behavior evolution process during hydraulic fracturing and enhancing the ability to identify abnormal energy absorption states.

[0121] By associating the energy absorption state interval identifier with the fracturing process control state based on the hydraulic control response module, this method can dynamically switch the fracturing process when the energy absorption state changes. By adjusting the pressure change amplitude and flow rate change rate in the hydraulic fracturing process in a coordinated manner, the current energy absorption state evolution interval can be returned to the preset stable interval, thereby achieving adaptive control of the fracturing process and reducing the risk of roof instability caused by abnormal energy accumulation and sudden release.

[0122] Through the above technical solution, this method can form a closed-loop control mechanism of "energy identification - state analysis - control response" in the hydraulic fracturing operation, transforming the fracturing process from the traditional experience-based and post-event control to a real-time control mode based on energy absorption state, thereby improving the safety, stability and controllability of hydraulic fracturing operations on the roof of coal mines, and has good engineering application value.

[0123] In another embodiment, this application also provides a computer storage medium storing computer-executable instructions, which, when executed, implement the aforementioned safe energy absorption method for hydraulic fracturing of coal mine roof.

[0124] The core innovation of this embodiment lies in abstracting the relationship between energy input and energy release during hydraulic fracturing into a quantifiable, comparable, and evolvable energy absorption state, and using the energy absorption state evolution range as the basic decision-making unit for fracturing process control. This allows the fracturing control logic to no longer rely on a single parameter or a fixed process flow, but to adaptively adjust according to changes in the energy absorption behavior of the rock formation.

[0125] This embodiment achieves a shift in fracturing safety control logic from "parameter threshold control" to "energy absorption state control." Instead of relying solely on static judgments based on single physical quantities such as pressure and flow rate, it reflects the true response of the rock formation through the continuous evolution of the energy absorption state. This makes the safety judgment of the fracturing process more closely aligned with the actual energy release mechanism, reducing misjudgments and delayed control.

[0126] Enhancing the ability to identify and respond to abnormal energy absorption processes, by identifying the magnitude of changes in the energy absorption state and its continuous evolution range, allows for early intervention and regulation before energy imbalance develops into severe instability, effectively reducing the likelihood of risk events such as abnormal energy accumulation and sudden release.

[0127] A dynamic switching mechanism for the fracturing process based on state is formed. The fracturing process is no longer a pre-set, immutable fixed process, but can be dynamically switched between different evolution ranges according to the energy absorption state, making fracturing operations more adaptable and flexible, especially suitable for coal mine environments with complex geological conditions and high uncertainty of roof response.

[0128] Constructing a closed-loop control path guided by a stable and gradual range improves the stability of the fracturing process. By unifying the control target of the fracturing process to a preset stable and gradual range, the system has a clear "regression target" when energy absorption anomalies occur. Furthermore, through the coordinated adjustment of pressure change amplitude and flow rate change rate, the fracturing process achieves self-recovery and stable operation.

[0129] This embodiment achieves state-based determination of fracturing operation termination conditions to avoid over-fracturing. It transforms the control of fracturing termination from manual experience or fixed time duration to a determination logic based on whether the energy absorption state has returned to a stable range. This effectively avoids ineffective water injection and excessive energy input, and improves operational safety and energy utilization efficiency.

[0130] The above embodiments are only used to illustrate the technical methods of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of this application without departing from the spirit and scope of the technical methods of this application.

Claims

1. A safe energy absorption method for hydraulic fracturing of the roof of a coal mine, characterized in that, Includes the following steps: Acquire pre-processed energy input and energy release data of the roof area of ​​the target coal mine within a preset time period; By mapping the energy input data and the energy release data to a time period, energy absorption response data of the hydraulic fracturing process can be obtained. Based on the energy absorption response data, it is determined whether the change in the ratio between the energy input data and the energy release data within a preset time period exceeds a preset threshold. If so, the continuous time period in which the change exceeds the preset threshold is defined as an energy absorption state evolution interval, and the corresponding energy absorption state interval identifier is obtained. Based on the energy absorption state interval identifier, the fracturing process control state of different energy absorption state evolution intervals during hydraulic fracturing is dynamically switched. When a change in the ratio between energy input data and energy release data is detected, the pressure change amplitude and flow rate change rate of the hydraulic fracturing process are adjusted based on the current energy absorption state interval identifier so that the energy absorption state evolution interval of the current time period is restored to a preset stable interval. The preset stable interval is the interval in which the energy absorption state interval identifier indicates that the hydraulic fracturing process is safe.

2. The safe energy absorption method for hydraulic fracturing of coal mine roof according to claim 1, characterized in that, The process of determining whether the change in the ratio between the energy input data and the energy release data exceeds a preset threshold within a preset time period includes: The ratio of energy input data to energy release data for each time period is calculated to obtain the energy absorption ratio sequence for each time period. The difference between adjacent time periods is calculated on the energy absorption ratio sequence to obtain the energy absorption ratio change amplitude sequence; The change range of each time period in the sequence of changes in the energy absorption ratio is compared with a preset threshold.

3. The safe energy absorption method for hydraulic fracturing of the coal mine roof according to claim 1, characterized in that, The process of obtaining the corresponding energy absorption state interval identifier is as follows: The energy input data and energy release data within the energy absorption state evolution interval are aggregated and calculated to obtain the interval-level energy absorption response data within the energy absorption state evolution interval. Time series trend analysis is performed on the interval-level energy absorption response data within the energy absorption state evolution interval, and the data is matched with a preset set of state classification thresholds to obtain the energy absorption state category to which the energy absorption state evolution interval belongs. A unique state code is assigned to each energy absorption state category. A correspondence is established between the energy absorption state category and the state code, and the association is performed to generate an energy absorption state interval identifier.

4. The safe energy absorption method for hydraulic fracturing of the coal mine roof according to claim 1, characterized in that, The process of dynamically switching between different energy absorption state evolution intervals during hydraulic fracturing includes: During the continuous hydraulic fracturing process, the energy absorption state interval identifier corresponding to the current time period is obtained, and the energy absorption state interval identifier is matched with the preset fracturing process control state to obtain the correspondence relationship; The hydraulic fracturing process is operated according to the preset fracturing process control state corresponding to the aforementioned relationship.

5. A safe energy absorption method for hydraulic fracturing of the coal mine roof according to claim 1, characterized in that, The process of adjusting the pressure change amplitude and flow rate change rate during hydraulic fracturing to restore the energy absorption state evolution range of the current time period to a preset stable range includes: The ratio change analysis is performed on the correspondence between the energy input data and the energy release data in adjacent time periods. When the ratio change meets the preset process switching trigger condition, the process control state of the current hydraulic fracturing process is switched to the control state corresponding to the preset energy absorption protection process, and an energy absorption protection trigger identifier is generated.

6. A safe energy absorption method for hydraulic fracturing of the coal mine roof according to claim 5, characterized in that, The process of adjusting the pressure change amplitude and flow rate change rate during hydraulic fracturing to restore the energy absorption state evolution range of the current time period to a preset stable range also includes: Based on the current energy absorption state interval identifier, extract the water injection pressure data and water injection flow data within the corresponding time range as continuous water injection time interval data; Using the time point corresponding to the energy absorption protection trigger mark as the boundary, the continuous water injection time interval data is divided into multiple time sub-intervals; the pressure change amplitude and flow rate change rate of the corresponding time sub-intervals are calculated respectively, and the time period is adjusted based on the pressure change amplitude and flow rate change rate to maintain it in a stable or slow-release state, and it is determined whether the energy absorption state evolution interval of the current time period has recovered to the preset stable interval.

7. A safe energy absorption method for hydraulic fracturing of the coal mine roof according to claim 6, characterized in that, The process of adjusting the time period based on the magnitude of pressure change and the rate of flow change to maintain it in a stable or slow-release state further includes: Based on the pressure change amplitude and the flow rate change rate, the interval attribute of each time sub-interval is determined, and the corresponding pressure stabilization interval identifier or slow release interval identifier is generated. Based on the pressure stabilization interval identifier or the slow release interval identifier, the distribution order of water injection pressure data and water injection flow data in the time dimension is adjusted so that each sub-time period corresponds to the water injection control parameters of the pressure stabilization stage or the slow release stage.

8. A safe energy absorption method for hydraulic fracturing of the coal mine roof according to claim 6, characterized in that, The process of determining whether the energy absorption state evolution range of the current time period has recovered to the preset stable range includes: During hydraulic fracturing, the energy absorption state evolution interval identifier corresponding to the current fracturing time period is obtained, and the energy absorption state evolution interval identifier is compared with the state identifier corresponding to the preset stable state interval to generate a stable state judgment result. When the stable state judgment result indicates that the energy absorption state interval identifier of the current energy absorption state evolution interval is in the preset stable state interval, the current hydraulic fracturing process enters a stable energy absorption state and ends the current hydraulic fracturing process.

9. A safety energy-absorbing device for hydraulic fracturing of coal mine roof, characterized in that: The application includes a safe energy absorption method for hydraulic fracturing of the coal mine roof as described in any one of claims 1 to 8, comprising: An energy identification module is used to acquire pre-processed energy input data and energy release data of the roof area of ​​a target coal mine within a preset time period; and to perform time-level correspondence between the energy input data and the energy release data to obtain energy absorption response data of the hydraulic fracturing process. The state analysis module is used to determine, based on the energy absorption response data, whether the change in the ratio between the energy input data and the energy release data within a preset time period exceeds a preset threshold. If so, the continuous time period in which the change exceeds the preset threshold is defined as an energy absorption state evolution interval, and the corresponding energy absorption state interval identifier is obtained. The hydraulic control response module is used to dynamically switch the fracturing process control state of different energy absorption state evolution intervals during hydraulic fracturing based on the energy absorption state interval identifier. When a change in the ratio between energy input data and energy release data is detected, the module adjusts the pressure change amplitude and flow rate change rate of the hydraulic fracturing process based on the current energy absorption state interval identifier so that the energy absorption state evolution interval of the current time period is restored to a preset stable interval. The preset stable interval is the interval in which the energy absorption state interval identifier indicates that the hydraulic fracturing process is safe.

10. A computer storage medium storing computer-executable instructions, characterized in that, When the computer-executable instructions are executed, they implement the safe energy absorption method for hydraulic fracturing of coal mine roof as described in any one of claims 1 to 8.

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