Crack parameter analysis method based on pump stop water hammer effect

Abstract

The invention discloses a fracture parameter analysis method based on a pump stop water hammer effect, and belongs to the technical field of fracture parameter analysis. The invention discloses a crack parameter analysis method based on a pump stopping water hammer effect. The crack parameter analysis method comprises the following steps: S1, collecting water hammer related parameters and water hammer pressure fluctuation signals during pump stopping; s2, noise elimination is carried out on the water hammer pressure fluctuation signal; s3, calculating the wave velocity and the pressure variation of the water hammer pressure wave; and S4, judging whether the pipeline has cracks or not, and analyzing the noise-reduced water hammer pressure wave signal. The problem that the number of cracks and the size and position of the cracks cannot be analyzed in the prior art is solved, the bearing capacity of the pipeline under different conditions can be predicted, so that the situation that the pipeline is broken due to the water hammer effect is avoided, the maintenance cost is reduced, accidental damage and the maintenance cost are reduced, the principle and influence of the water hammer effect can be known, and the application prospect is wide. Coping strategies can be prepared in advance, and losses in emergency situations are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of crack parameter analysis, and in particular to a crack parameter analysis method based on pump-stop water hammer effect. Background Art

[0002] Pressure transients can cause invisible cracks in buried pipes, pipe fittings and pipe accessories, and even cause serious pipeline ruptures. Currently, water hammer monitors are mainly installed at key locations of pipelines to monitor and collect pressure transient signals for pressure transient (water hammer) analysis.

[0003] Chinese patent publication number CN116981828A discloses a method for determining the characteristics of hydraulic fracturing based on in-well pressure measurements taken after stopping pumping fracturing fluid into the well (shut-in), which includes determining a first time after shut-in, after which the measured pressure reduction is caused by fluid leakage in the fracture. Determining a second time after shut-in, after which the pressure reduction is caused by fluid leakage, fracture growth, and fluid pressure balance in the fracture. Determining a third time after shut-in, after which the pressure reduction is caused by fluid leakage, fracture growth, fluid pressure balance in the fracture, and pressure drop in the near-wellbore region. The values ​​of fluid efficiency, minimum stress, and net pressure determined are such that the calculated pressure relative to time matches the pressure measurement within a predetermined threshold.

[0004] In actual use, the above patent cannot analyze the number, size and location of cracks, which leads to the inability to judge the risk of the pipeline based on the specific parameters of the cracks; therefore, it does not meet the existing needs. We propose a crack parameter analysis method based on the water hammer effect of pump stop. Summary of the invention

[0005] The purpose of the present invention is to provide a crack parameter analysis method based on the water hammer effect when the pump is stopped, which can predict the bearing capacity of water pipes under different conditions, thereby avoiding the rupture of water pipes due to the water hammer effect, and can evaluate the safety performance of water conservancy facilities, ensure their long-term stable operation, reduce maintenance costs, reduce accidental damage and repair costs, understand the principles and impacts of the water hammer effect, prepare response strategies in advance, reduce losses in emergency situations, and solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a crack parameter analysis method based on pump-off water hammer effect, comprising the following steps:

[0007] S1: Install a data acquisition module at the wellhead, use the data acquisition module to collect water hammer related parameters when the pump is stopped, and obtain a water hammer pressure fluctuation signal;

[0008] S2: Use the decomposition and noise reduction module to eliminate various random noises and fixed frequency noises in the water hammer pressure fluctuation signal;

[0009] S3: Calculate the wave velocity of the water hammer pressure wave and the pressure change of the water hammer using water hammer related parameters;

[0010] S4: The judgment and analysis module judges whether there are cracks in the pipeline according to the calculation results, and analyzes the water hammer pressure wave signal after noise reduction to obtain the location, length, width and number of cracks.

[0011] Preferably, the data acquisition module comprises:

[0012] A data acquisition module, used to acquire the flow velocity and density of the fluid, the flow velocity change of the fluid, the wall thickness and inner diameter of the pipeline, the elastic modulus of the pipeline, and the elastic modulus of the fluid;

[0013] The data transmission module is used to transmit the monitored data and encrypt and protect the data during the data transmission process.

[0014] Preferably, obtaining the water hammer pressure fluctuation signal specifically includes:

[0015] The intrinsic mode function components with different frequencies are obtained through empirical mode decomposition, and the high-frequency noise components are eliminated and the signal is reconstructed according to the frequency domain characteristics of the water hammer signal.

[0016] A time series prediction model based on a recurrent neural network model is established to obtain water hammer impact signals, and the training and parameters of the recurrent neural network model are adjusted according to the obtained water hammer impact signals;

[0017] The water hammer impact signals at different flow rates are obtained, and the water hammer impact signals at different flow rates are input into the time series prediction model to obtain the water hammer pressure wave signal.

[0018] Preferably, the use of eliminating various random noises and fixed frequency noises present in the water hammer pressure fluctuation signal specifically includes:

[0019] The noisy water hammer pressure wave signal is decomposed by empirical mode decomposition to obtain multiple intrinsic mode function components;

[0020] Analyze the components of the intrinsic mode function and identify the intrinsic mode function containing noise;

[0021] According to the analysis results, the intrinsic modal function components containing effective water hammer pressure wave signals are retained, while the intrinsic modal function components mainly composed of noise are removed;

[0022] The selected intrinsic mode function components are reconstructed to obtain the de-noised water hammer pressure wave signal.

[0023] Preferably, the decomposition and noise reduction module comprises:

[0024] A decomposition module, used for decomposing and analyzing the noisy water hammer pressure wave signal through empirical mode decomposition;

[0025] The noise reduction module is used to perform noise reduction and reconstruction according to the intrinsic modal function components of the analysis results to obtain the water hammer pressure wave signal after noise reduction.

[0026] Preferably, the calculation of the wave velocity of the water hammer pressure wave and the pressure change of the water hammer by using water hammer related parameters specifically includes:

[0027] The wave velocity of the water hammer pressure wave is calculated according to the obtained fluid density, pipe wall thickness and pipe inner diameter, pipe wall elastic modulus and fluid elastic modulus;

[0028] The pressure change of the water hammer is calculated based on the obtained density and flow velocity of the fluid and the change of the flow velocity of the fluid and the wave velocity of the water hammer pressure wave.

[0029] Preferably, the calculation formula of the water hammer pressure wave velocity is as follows:

[0030]

[0031] Among them, V ω is the velocity of water hammer pressure wave, K is the elastic modulus of the fluid, ρ is the fluid density, t is the pipe wall thickness, r is the inner diameter of the pipe, and E is the elastic modulus of the pipe wall;

[0032] The calculation formula for the pressure change of water hammer is as follows;

[0033] ΔP=V ω *S*ΔS*ρ*10 -5

[0034] Among them, ΔP is the pressure change of water hammer, S is the flow rate of the fluid, and ΔS is the change of the fluid flow rate.

[0035] Preferably, the judgment and analysis module includes:

[0036] A judgment module, used to judge whether there are cracks in the pipeline according to the calculation results of the water hammer pressure wave velocity and the pressure change of the water hammer, and if there are cracks, to judge the location and number of the cracks;

[0037] The analysis module is used to determine the length and width of the pipeline crack according to the analysis result of the water hammer pressure wave signal.

[0038] Preferably, the judgment module specifically includes:

[0039] The water hammer pressure wave signal is used to perform spectrum analysis to obtain the time it takes for the pressure wave fluctuation at the fracture location to propagate to the wellhead, i.e., the response time.

[0040] The crack location is calculated by multiplying the response time, pressure wave velocity, and pressure change of the water hammer.

[0041] Calculate the water hammer pressure wave velocity and water hammer pressure change in different time periods, and analyze the pressure wave reflection and attenuation of the pump stop water hammer based on the calculation results;

[0042] Analyze the changes in pressure waveform of pressure wave reflection, and determine the number of cracks after the pump is stopped due to water hammer based on the changes and attenuation of pressure waveform of pressure wave reflection.

[0043] Preferably, the analysis module specifically includes

[0044] The spectrum of the water hammer pressure wave signal is obtained by using fast Fourier transform, the time domain signal in the spectrum of the water hammer pressure wave signal is converted into the frequency domain, and the frequency distribution and main frequency components in the spectrum are analyzed;

[0045] Analyze the amplitude of different frequency components in the spectrum of the water hammer pressure wave signal, and then analyze the amplitude change of the water hammer pressure wave signal;

[0046] Identify the frequency components related to the water hammer effect in the water hammer pressure wave signal spectrum, record the starting and ending positions of the specific frequency components in the water hammer pressure wave signal spectrum, and obtain the duration of the water hammer pressure wave signal;

[0047] The length and width of the crack are analyzed based on the frequency, amplitude changes and duration of the water hammer pressure wave signal.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] By analyzing the crack parameters, the present invention can understand the length and width of the cracks, as well as determine the location and number of the cracks, and can predict the bearing capacity of the pipeline under different conditions, thereby avoiding the pipeline from rupturing due to the water hammer effect. By accurately measuring the size and number of water hammer cracks, the safety performance of water conservancy facilities can be evaluated to ensure their long-term stable operation and reduce maintenance costs. Accurate size and quantity measurements can help predict the maintenance needs of water conservancy facilities, thereby reasonably arranging maintenance plans, reducing accidental damage and repair costs. The principle and impact of the water hammer effect can be understood, and response strategies can be prepared in advance to reduce losses in emergency situations. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a flow chart of the crack parameter analysis method based on the pump-off water hammer effect of the present invention;

[0051] Figure 2 It is a system diagram of the crack parameter analysis method based on the pump-off water hammer effect of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] In order to solve the problem that the existing patents cannot analyze the number, size and location of cracks in actual use, and thus cannot judge the risk of pipelines based on the specific parameters of cracks, please refer to Figure 1-Figure 2 , this embodiment provides the following technical solutions:

[0054] The crack parameter analysis method based on the pump-off water hammer effect includes the following steps:

[0055] S1: Install a data acquisition module at the wellhead, use the data acquisition module to collect water hammer related parameters when the pump is stopped, and obtain a water hammer pressure fluctuation signal;

[0056] During the fracturing pump stop process, the water hammer pressure wave signal actually collected will contain a large amount of random noise and fixed frequency noise. The presence of these noises will strongly interfere with the fracturing pump stop spectrum analysis and the determination of response time, affecting the accuracy of the analysis. Therefore, it is the key to improve the accuracy of diagnosis to remove various random noises and fixed frequency noises in the pump stop process through reasonable filtering methods and improve the signal-to-noise ratio. Filtering technology includes analog filtering and digital filtering. Modern filtering technologies such as Kalman filtering, adaptive filtering, particle filtering, etc. have gradually replaced traditional classical filtering technologies. The combined use of multiple filtering technologies can further improve the effect.

[0057] S2: Use the decomposition and noise reduction module to eliminate various random noises and fixed frequency noises in the water hammer pressure fluctuation signal. By eliminating the noise interference of the water hammer pressure fluctuation signal, the head loss caused by the pump stop water hammer can be reduced, the water utilization efficiency can be improved, the operation status of the water pump can be optimized, unnecessary power consumption can be reduced, the water pump and pipeline system can be protected, the frequency of maintenance and replacement can be reduced, and the service life of the equipment and pipelines can be extended;

[0058] S3: The velocity of the water hammer pressure wave and the pressure change of the water hammer are calculated using water hammer related parameters. The location and number of cracks can be determined using the velocity of the water hammer pressure wave and the pressure change of the water hammer, thus ensuring the accuracy of the crack location determination.

[0059] S4: The judgment and analysis module determines whether there are cracks in the pipeline based on the calculation results, and analyzes the water hammer pressure wave signal after noise reduction to obtain the location, length, width and number of cracks. By determining the number of water hammer cracks, the overall safety status of the pipeline system can be evaluated. A large number of cracks may mean that the structural integrity of the pipeline system is greatly affected, and corresponding repair or reinforcement measures need to be taken to prevent potential safety accidents. The determination of the number of cracks helps to formulate a more scientific and reasonable maintenance plan. For areas with a large number of cracks, repair or replacement can be arranged first to ensure the normal operation of the pipeline system. The ability to detect and deal with cracks in a timely manner can avoid more serious damage caused by further expansion of cracks, thereby saving maintenance costs. In addition, a reasonable maintenance plan can also help extend the service life of the pipeline system and reduce long-term operating costs. Being able to understand the crack situation of the pipeline system helps to optimize its design and operating parameters. For example, the material, wall thickness or operating pressure of the pipeline can be adjusted according to the distribution and number of cracks to improve the overall performance of the pipeline system.

[0060] Data acquisition module, including:

[0061] A data acquisition module, used to acquire the flow velocity and density of the fluid, the flow velocity change of the fluid, the wall thickness and inner diameter of the pipeline, the elastic modulus of the pipeline, and the elastic modulus of the fluid;

[0062] The data transmission module is used to transmit the monitored data and encrypt and protect the data during the data transmission process. By encrypting and protecting the data during data transmission, the security of data transmission is guaranteed, and the data is prevented from being tampered with or stolen, thereby ensuring the accuracy of data analysis. Obtaining the water hammer pressure fluctuation signal specifically includes:

[0063] The intrinsic mode function components with different frequencies are obtained through empirical mode decomposition, and the high-frequency noise components are eliminated and the signal is reconstructed according to the frequency domain characteristics of the water hammer signal.

[0064] A time series prediction model based on a recurrent neural network model is established to obtain water hammer impact signals, and the training and parameters of the recurrent neural network model are adjusted according to the obtained water hammer impact signals;

[0065] The water hammer impact signals at different flow rates are obtained, and the water hammer impact signals at different flow rates are input into the time series prediction model to obtain the water hammer pressure wave signal.

[0066] Use to eliminate various random noises and fixed frequency noises in the water hammer pressure fluctuation signal, including:

[0067] The noisy water hammer pressure wave signal is decomposed by empirical mode decomposition to obtain multiple intrinsic mode function components;

[0068] Analyze the components of the intrinsic mode function and identify the intrinsic mode function containing noise;

[0069] According to the analysis results, the intrinsic modal function components containing effective water hammer pressure wave signals are retained, while the intrinsic modal function components mainly composed of noise are removed;

[0070] The selected intrinsic mode function components are reconstructed to obtain the de-noised water hammer pressure wave signal.

[0071] Decomposition noise reduction module, including

[0072] A decomposition module, used for decomposing and analyzing the noisy water hammer pressure wave signal through empirical mode decomposition;

[0073] The noise reduction module is used to perform noise reduction and reconstruction according to the intrinsic modal function components of the analysis results to obtain the water hammer pressure wave signal after noise reduction.

[0074] The velocity of the water hammer pressure wave and the pressure change of the water hammer are calculated using water hammer related parameters, including:

[0075] The velocity of the water hammer pressure wave is calculated based on the obtained fluid density, pipe wall thickness and inner diameter, pipe wall elastic modulus and fluid elastic modulus. Calculating the velocity of the water hammer pressure wave helps to predict and evaluate the impact of the water hammer phenomenon on the pipeline system, so as to take corresponding preventive measures, such as optimizing valve operation and improving pipeline design, to reduce the occurrence of water hammer phenomenon and the damage caused by it;

[0076] The pressure change of the water hammer is calculated based on the obtained density and flow velocity of the fluid and the change of the flow velocity of the fluid and the wave velocity of the water hammer pressure wave, thereby improving the safety and efficiency of the system.

[0077] The calculation formula of water hammer pressure wave velocity is as follows:

[0078]

[0079] Among them, V ω is the velocity of water hammer pressure wave, K is the elastic modulus of the fluid, ρ is the fluid density, t is the pipe wall thickness, r is the inner diameter of the pipe, and E is the elastic modulus of the pipe wall. The greater the pressure, the greater the crack width.

[0080] The calculation formula for the pressure change of water hammer is as follows;

[0081] ΔP=V ω *S*ΔS*ρ*10 -5

[0082] Among them, ΔP is the pressure change of water hammer, S is the flow rate of the fluid, and ΔS is the change of the fluid flow rate. The judgment and analysis module includes:

[0083] A judgment module, used to judge whether there are cracks in the pipeline according to the calculation results of the water hammer pressure wave velocity and the pressure change of the water hammer, and if there are cracks, to judge the location and number of the cracks;

[0084] The analysis module is used to determine the length and width of the pipeline crack according to the analysis result of the water hammer pressure wave signal.

[0085] The judgment module specifically includes:

[0086] The water hammer pressure wave signal is used to perform spectrum analysis to obtain the time it takes for the pressure wave fluctuation at the fracture location to propagate to the wellhead, i.e., the response time.

[0087] The crack location is calculated by multiplying the response time, pressure wave velocity, and pressure change of the water hammer.

[0088] Calculate the water hammer pressure wave velocity and water hammer pressure change in different time periods, and analyze the pressure wave reflection and attenuation of the pump stop water hammer based on the calculation results;

[0089] Analyze the changes in pressure waveform of pressure wave reflection, and determine the number of cracks after the pump is stopped due to water hammer based on the changes and attenuation of pressure waveform of pressure wave reflection.

[0090] Analysis module, including

[0091] The spectrum of the water hammer pressure wave signal is obtained by using fast Fourier transform, the time domain signal in the spectrum of the water hammer pressure wave signal is converted into the frequency domain, and the frequency distribution and main frequency components in the spectrum are analyzed;

[0092] By analyzing the spectral characteristics of the water hammer signal, the location of the crack or bottom hole event can be determined. Specifically, when the pump is stopped, the wellhead pressure drops rapidly to 0, and the fluid in the wellbore forms a water hammer pressure wave due to compression oscillation. When there are cracks or leaks in the wellbore, the fluid will flow into these locations, causing pressure fluctuations. These fluctuation signals will be transmitted back to the wellhead along with the water hammer pressure wave signal. Through spectrum analysis, the time it takes for the pressure wave fluctuation at the crack location to propagate to the wellhead, that is, the response time, can be obtained. The response time multiplied by the pressure wave velocity can determine the location of the crack, and then the location of the crack can be located, which can timely discover and solve problems, avoid potential pipeline ruptures or equipment damage, and ensure the safe operation of the system.

[0093] Analyze the amplitude of different frequency components in the spectrum of the water hammer pressure wave signal, and then analyze the amplitude change of the water hammer pressure wave signal;

[0094] Identifying the frequency components related to the water hammer effect in the water hammer pressure wave signal spectrum, recording the starting and ending positions of the specific frequency components in the water hammer pressure wave signal spectrum, and obtaining the duration of the water hammer pressure wave signal can more accurately determine the duration of the water hammer pressure wave signal. The change in amplitude in the spectrum can also provide information about the intensity and duration of the water hammer effect. Frequency components with larger amplitudes usually indicate a stronger water hammer effect, while a trend of gradually decreasing amplitudes indicates that the water hammer effect is weakening over time.

[0095] The length and width of the cracks are analyzed based on the frequency, amplitude changes and duration of the water hammer pressure wave signal. By analyzing these signals, the condition of the cracks can be evaluated, thereby achieving an accurate determination of the number of cracks:

[0096] These frequency components reflect the propagation speed and attenuation of the water hammer pressure wave in the pipeline. The amplitude of the pressure wave reflects the impact of the water hammer phenomenon on the pipeline system. A larger amplitude may mean that the water hammer phenomenon is more severe, which may cause greater impact and damage to the pipeline system. By analyzing the amplitude of the pressure wave signal, the severity of the water hammer phenomenon can be evaluated, so that corresponding measures can be taken to reduce its impact on the pipeline system.

[0097] In summary, the crack parameter analysis method based on the pump-off water hammer effect of the present invention can reduce the head loss caused by the pump-off water hammer by eliminating the noise interference of the water hammer pressure fluctuation signal, improve the water utilization efficiency, optimize the operating state of the water pump, reduce unnecessary power consumption, protect the water pump and pipeline system, reduce the frequency of maintenance and replacement, and thus extend the service life of the equipment and pipeline. By analyzing the crack parameters, the length and width of the cracks can be understood, and the location and number of the cracks can be determined. The bearing capacity of the pipeline under different conditions can be predicted, thereby avoiding the pipeline from rupturing due to the water hammer effect. By accurately measuring the size and number of water hammer cracks, the safety performance of water conservancy facilities can be evaluated to ensure their long-term stable operation and reduce maintenance costs. Accurate size and quantity measurement can help predict the maintenance needs of water conservancy facilities, thereby reasonably arranging maintenance plans, reducing accidental damage and repair costs, and understanding the principles and impacts of the water hammer effect. , Prepare response strategies in advance to reduce losses in emergency situations, and locate the location of the cracks. Problems can be discovered and solved in a timely manner to avoid potential pipeline rupture or equipment damage, and ensure the safe operation of the system.

[0098] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0099] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A crack parameter analysis method based on the pump-off water hammer effect, characterized in that: The following steps are involved: S1: Install a data acquisition module at the wellhead, use the data acquisition module to collect water hammer related parameters when the pump is stopped, and obtain a water hammer pressure fluctuation signal; S2: Use the decomposition and noise reduction module to eliminate various random noises and fixed frequency noises existing in the water hammer pressure fluctuation signal; S3: Calculate the velocity of the water hammer pressure wave and the pressure change of the water hammer using water hammer related parameters; S4: The judgment and analysis module judges whether there are cracks in the pipeline according to the calculation results, and analyzes the water hammer pressure wave signal after noise reduction to obtain the location, length, width and number of cracks.

2. The crack parameter analysis method based on pump-off water hammer effect according to claim 1 is characterized in that: The data acquisition module comprises: A data acquisition module, used to acquire the flow velocity and density of the fluid, the flow velocity change of the fluid, the wall thickness and inner diameter of the pipeline, the elastic modulus of the pipeline, and the elastic modulus of the fluid; The data transmission module is used to transmit the monitored data and encrypt and protect the data during the data transmission process.

3. The crack parameter analysis method based on pump-off water hammer effect according to claim 1 is characterized in that: The obtaining of the water hammer pressure fluctuation signal specifically includes: The intrinsic mode function components with different frequencies are obtained through empirical mode decomposition, and the high-frequency noise components are eliminated and the signal is reconstructed according to the frequency domain characteristics of the water hammer signal. A time series prediction model based on a recurrent neural network model is established to obtain water hammer impact signals, and the training and parameters of the recurrent neural network model are adjusted according to the obtained water hammer impact signals; The water hammer impact signals at different flow rates are obtained, and the water hammer impact signals at different flow rates are input into the time series prediction model to obtain the water hammer pressure wave signal.

4. The crack parameter analysis method based on pump-off water hammer effect according to claim 1 is characterized in that: The method of eliminating various random noises and fixed frequency noises existing in the water hammer pressure fluctuation signal specifically includes: The noisy water hammer pressure wave signal is decomposed by empirical mode decomposition to obtain multiple intrinsic mode function components; Analyze the components of the intrinsic mode function and identify the intrinsic mode function containing noise; According to the analysis results, the intrinsic modal function components containing effective water hammer pressure wave signals are retained, while the intrinsic modal function components mainly composed of noise are removed; The selected intrinsic mode function components are reconstructed to obtain the de-noised water hammer pressure wave signal.

5. The crack parameter analysis method based on pump-off water hammer effect according to claim 1 is characterized in that: The decomposition and noise reduction module comprises A decomposition module, used for decomposing and analyzing the noisy water hammer pressure wave signal through empirical mode decomposition; The noise reduction module is used to perform noise reduction and reconstruction according to the intrinsic modal function components of the analysis results to obtain the water hammer pressure wave signal after noise reduction.

6. The crack parameter analysis method based on pump-off water hammer effect according to claim 1 is characterized in that: The calculation of the wave velocity of the water hammer pressure wave and the pressure variation of the water hammer by using the water hammer related parameters specifically includes: The wave velocity of the water hammer pressure wave is calculated according to the obtained fluid density, pipe wall thickness and pipe inner diameter, pipe wall elastic modulus and fluid elastic modulus; The pressure change of the water hammer is calculated based on the obtained density and flow velocity of the fluid and the change of the flow velocity of the fluid and the wave velocity of the water hammer pressure wave.

7. The crack parameter analysis method based on pump-off water hammer effect according to claim 6 is characterized in that: The calculation formula of the water hammer pressure wave velocity is as follows: Among them, V ω is the velocity of water hammer pressure wave, K is the elastic modulus of the fluid, ρ is the fluid density, t is the pipe wall thickness, r is the inner diameter of the pipe, and E is the elastic modulus of the pipe wall; The calculation formula for the pressure change of water hammer is as follows; ΔP=V ω *S*ΔS*ρ*10 -5 Among them, ΔP is the pressure change of water hammer, S is the flow rate of the fluid, and ΔS is the change of the fluid flow rate.

8. The crack parameter analysis method based on pump-off water hammer effect according to claim 1 is characterized in that: The judgment and analysis module comprises: A judgment module, used to judge whether there are cracks in the pipeline according to the calculation results of the water hammer pressure wave velocity and the pressure change of the water hammer, and if there are cracks, to judge the location and number of the cracks; The analysis module is used to determine the length and width of the pipeline crack according to the analysis result of the water hammer pressure wave signal.

9. The crack parameter analysis method based on pump-off water hammer effect according to claim 8 is characterized in that: The judgment module specifically includes: The water hammer pressure wave signal is used to perform spectrum analysis to obtain the time it takes for the pressure wave fluctuation at the fracture location to propagate to the wellhead, i.e., the response time. The crack location is calculated by multiplying the response time, pressure wave velocity, and pressure change of the water hammer. Calculate the water hammer pressure wave velocity and water hammer pressure change in different time periods, and analyze the pressure wave reflection and attenuation of the pump stop water hammer based on the calculation results; Analyze the changes in pressure waveform of pressure wave reflection, and determine the number of cracks after the pump is stopped due to water hammer based on the changes and attenuation of pressure waveform of pressure wave reflection.

10. The crack parameter analysis method based on pump-off water hammer effect according to claim 8, characterized in that: The analysis module specifically includes The spectrum of the water hammer pressure wave signal is obtained by using fast Fourier transform, the time domain signal in the spectrum of the water hammer pressure wave signal is converted into the frequency domain, and the frequency distribution and main frequency components in the spectrum are analyzed; Analyze the amplitude of different frequency components in the spectrum of the water hammer pressure wave signal, and then analyze the amplitude change of the water hammer pressure wave signal; Identify the frequency components related to the water hammer effect in the water hammer pressure wave signal spectrum, record the starting and ending positions of the specific frequency components in the water hammer pressure wave signal spectrum, and obtain the duration of the water hammer pressure wave signal; The length and width of the crack are analyzed based on the frequency, amplitude changes and duration of the water hammer pressure wave signal.

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