Underwater manifold leakage positioning method and system based on dynamic pressure signals

Abstract

The invention belongs to the technical field of petroleum engineering, and particularly relates to an underwater manifold leakage positioning method and system based on dynamic pressure signals. According to the underwater manifold leakage positioning method and system based on the dynamic pressure signals, accurate positioning of leakage of an underwater manifold production system is achieved by calculating the leakage characteristics of the collected dynamic pressure signals and correcting the propagation speed of the pressure waves, and the method and system are provided for achieving quick response of leakage monitoring. And technical support is provided for guaranteeing the continuity of underwater production. The invention provides an underwater manifold leakage positioning method based on a dynamic pressure signal. The underwater manifold leakage positioning method comprises the following steps that P1, leakage characteristics of the dynamic pressure signal under the condition of a multiphase flow medium are calculated; p2, the propagation speed of the dynamic pressure signal under the multiphase flow medium condition is corrected; and P3, performing leakage positioning calculation on the underwater manifold under the condition of the multiphase flow medium.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum engineering, and in particular relates to a method and a system for locating underwater manifold leakage based on dynamic pressure signals. Background Art

[0002] As an important production facility in the development of offshore oil and natural gas, underwater manifolds are mainly used to collect and transport fluids generated by seabed wellheads to platforms or other production facilities. However, due to the complex structure of underwater manifolds and the special working environment, they face a variety of risks that may cause leakage, such as pipeline aging, wear, corrosion and external forces. The above risks not only lead to a decrease in the production efficiency of underwater manifolds and cause additional economic losses, but may also have a serious impact on the marine ecological environment.

[0003] Further research has found that the dynamic pressure (fluctuation) signal generated by the leakage of the internal fluid of the underwater manifold can be monitored by using pressure wave sensors or other sensing devices; and when abnormal pressure drops or fluctuates rapidly, the leakage of the underwater manifold can be determined and identified. In addition, by installing multiple pressure sensing devices at different locations, the specific location of the leakage point can be calculated based on time inversion or other algorithms according to the time difference of the pressure wave reaching each sensing device.

[0004] However, the inventors found that the structure of the existing underwater manifolds in service is very complex (support structures, anti-fishing nets and other protective equipment are also integrated on the outside), and the underwater environment is changeable and noisy, which brings great difficulty to monitoring the dynamic pressure signals generated by leakage. Therefore, it is urgent for those skilled in the art to design and provide a new underwater manifold leakage positioning method and system to achieve online monitoring and precise positioning of underwater manifold leakage, so as to quickly respond to potential leakage events and provide assistance to ensure the safe and efficient development of oil and gas production. Summary of the invention

[0005] The present invention provides a method and system for locating underwater manifold leakage based on dynamic pressure signals. By calculating the leakage characteristics of the collected dynamic pressure signals and correcting the pressure wave propagation velocity, accurate positioning of underwater manifold production system leakage is achieved, providing technical support for rapid response of leakage monitoring and ensuring the continuity of underwater production.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: The underwater manifold leakage locating method based on dynamic pressure signal includes the following steps: Step P1: Calculate the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions; Step P2: Correcting the propagation velocity of the dynamic pressure signal under multiphase flow medium conditions; Step P3: Calculate the leakage location of the underwater manifold under multiphase flow medium conditions.

[0007] Preferably, the process of calculating the leakage characteristics of the dynamic pressure signal under the multiphase flow medium condition in step P1 is specifically described as follows: Step P101: performing modal decomposition on the leakage characteristics of the dynamic pressure signal under the multiphase flow medium condition, and decomposing it into multiple inherent modal functions; Step P102: performing Hilbert-Huang transform on each intrinsic mode function to obtain the instantaneous frequency and instantaneous amplitude of each intrinsic mode function; Step P103: weighting the instantaneous amplitude and describing it in the time-frequency plane dimension to obtain the Hilbert spectrum of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow; Step P104: Based on a statistical method, the amplitude characteristics of the pressure drop change rate in the leakage characteristics of the dynamic pressure signal generated by the leakage of fluids in different phases are analyzed.

[0008] Preferably, the step P102 is specifically described as follows: The Hilbert-Huang transform of any intrinsic mode function c(t) satisfies: (1); In formula (1), c(t) represents the intrinsic mode function; P represents the Cauchy principal value; τ represents the time difference; Among them, the analytical signal z(t) of the intrinsic mode function further satisfies: (2); In formula (2), t represents time; A(t) represents the instantaneous amplitude of the intrinsic mode function c(t); represents the instantaneous phase of the intrinsic mode function c(t); Instantaneous amplitude A(t) and instantaneous phase , respectively satisfying: (3); (4); For instantaneous phase Take the derivative and get the instantaneous frequency ,satisfy: (5).

[0009] Preferably, the Hilbert spectrum of the dynamic pressure signal under the gas-liquid two-phase intermittent flow condition obtained in step P103 satisfies: (6); Further, by performing time integration on equation (6), the Hilbert yellow edge spectrum of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow medium is obtained, which satisfies: (7).

[0010] Preferably, the amplitude characteristic of the pressure drop change rate in the leakage characteristic of the dynamic pressure signal generated by the leakage of fluids in different phases in step P104 satisfies: (8); In formula (8), r represents the voltage drop change rate; t represents time; x(t) represents the discrete time signal; and n represents the number of data points.

[0011] Preferably, the process of correcting the propagation velocity of the dynamic pressure signal under the multiphase flow medium condition in step P2 is specifically described as follows: The propagation speed of the dynamic pressure signal under single-phase fluid medium conditions satisfies: (9); In formula (9), K represents the fluid bulk elastic modulus coefficient; ρ represents the fluid bulk density function; Among them, the fluid bulk elastic modulus coefficient K satisfies: (10); In formula (10), α represents the compressibility coefficient; V represents the volume of the fluid medium; dp represents the pressure; According to the mass relationship, the fluid volume satisfies: (11); Substituting formula (11) into formula (10), we get: (12); Substituting formula (12) into formula (9), we get: (13); The propagation velocity of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow medium is further derived to satisfy: (14); In formula (14), K g Represents the bulk elastic modulus of the gas in the tube; K l Represents the bulk elastic modulus of the liquid in the tube; K a represents the bulk elastic modulus of the pipeline material; β represents the volumetric gas content of the gas-liquid two-phase flow; D represents the inner diameter of the pipeline; e represents the wall thickness of the pipeline; ρ l represents the density of the liquid in the tube; ρ g Indicates the density of gas in the tube; The gas-liquid flow ratio is introduced; the gas-liquid flow ratio refers to the ratio of the gas phase flow to the liquid phase flow, which satisfies: (15); In formula (15), q g Indicates the volume flow rate of gas in the pipe; q l Indicates the volume flow rate of the liquid in the pipe; Among them, the volume gas content satisfies: (16); In formula (16), V g Indicates the volume of gas in the tube; V l Indicates the volume of liquid in the tube; The cross-sectional area of ​​the pipe in the underwater manifold is defined as A, then the flow velocity u of the gas phase and liquid phase in the fluid medium is g 、u l , respectively satisfying: (17); The volumetric gas content in the tube within a certain time t is derived to satisfy: (18); Then the relationship between volume gas content and gas-liquid flow ratio satisfies: (19); Substituting equation (19) into equation (14), we obtain the propagation velocity correction formula of the dynamic pressure signal under multiphase flow medium conditions, which satisfies: (20); In formula (20), K g Represents the bulk elastic modulus of the gas in the tube; K l Represents the bulk elastic modulus of the liquid in the tube; K a represents the bulk elastic modulus of the pipeline material; β represents the gas-liquid ratio under multiphase flow medium conditions; D represents the inner diameter of the pipeline; e represents the wall thickness of the pipeline; ρ l represents the density of the liquid in the tube; ρ g Indicates the density of the gas in the tube.

[0012] Preferably, the process of calculating the leakage location of the underwater manifold under the multiphase flow medium condition in step P3 is specifically described as: leakage point location, satisfying: (27); In formula (27), X represents the leakage location; L represents the distance between the two sensors in the positioning network; v represents the propagation speed of the corrected dynamic pressure signal; Δt represents the time difference.

[0013] Preferably, before implementing step P3, the following steps are also included: Step P30: Perform wavelet packet filtering preprocessing on the dynamic pressure signal under multiphase flow medium conditions.

[0014] On the other hand, the present invention also provides an underwater manifold leakage positioning system based on dynamic pressure signals, comprising: a main control station, and an underwater control module installed inside a basic frame of the underwater manifold; The master control station includes: a power carrier communication module host computer, an industrial control mainboard and a display; The underwater control module includes: a cabin structure, a dynamic pressure signal acquisition control instruction reading unit, a dynamic pressure signal acquisition unit and a power carrier communication lower computer which are sealed and arranged in the cabin structure; Among them, through the power cable in the umbilical cable, a communication connection is established between the power carrier communication module host computer and the power carrier communication slave computer.

[0015] Preferably, the main control station further comprises: a leakage locating module; The leakage locating module includes: a dynamic pressure signal acquisition control instruction sending unit, a dynamic pressure signal receiving unit, a dynamic pressure signal storage unit, a dynamic pressure signal reading unit, a dynamic pressure signal noise reduction unit, a dynamic pressure signal processing unit, a leakage locating result transmission unit, a leakage locating result verification unit, and a leakage locating result display unit.

[0016] The present invention provides a method and system for locating underwater manifold leakage based on dynamic pressure signals. The method for locating underwater manifold leakage includes the following steps: step P1: calculating the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions; step P2: correcting the propagation speed of the dynamic pressure signal under multiphase flow medium conditions; step P3: performing leakage location calculation on the underwater manifold under multiphase flow medium conditions.

[0017] The present invention provides a method and system for locating underwater manifold leakage based on dynamic pressure signals, which has at least the following technical advantages compared with the prior art: (1) This underwater manifold leakage location method and system collects the dynamic pressure signal under the multiphase flow medium condition in the underwater manifold pipeline; and after extracting the leakage characteristics, it realizes the rapid response location calculation of the underwater manifold leakage. The leakage location result is real-time and reliable, which helps to realize the real-time monitoring of underwater manifold leakage and provides technical support for ensuring the continuity of underwater manifold production; (2) This underwater manifold leakage locating method and system adopts the technical means of calculating the leakage characteristics of the dynamic pressure signal under the condition of multiphase flow medium and correcting the propagation speed of the dynamic pressure signal under the condition of multiphase flow medium, which effectively improves the accuracy of the leakage locating results and provides help for technical personnel to reveal the operating status of the underwater manifold under different phase media and grasp the specific location of the leakage point. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the following drawings: Figure 1 A schematic flow chart of a method for locating underwater manifold leakage based on dynamic pressure signals provided by the present invention; Figure 2 It is a schematic diagram of the decomposition structure of wavelet packet filter transform in the process of wavelet packet filter preprocessing of dynamic pressure signal under multiphase flow medium condition; Figure 3 A structural schematic diagram of a main control station in an underwater manifold leakage locating system based on dynamic pressure signals provided by the present invention; Figure 4 The electrical structure block diagram of the underwater control module in the main control station; Figure 5 An electrical structure block diagram of a leakage locating module in an underwater manifold leakage locating system based on dynamic pressure signals provided by the present invention; Reference numerals: 101. Display, 102. Keyboard, 103. Touchpad, 104. Industrial control motherboard, 105. Impact-resistant corner wrap, 106. Control cabinet buckle, 107. Portable handle, 108. Uninterruptible power supply battery, 109. Control cabinet C shell, 110. Power carrier communication module host computer, 111. Uninterruptible power supply AC-DC converter, 112. Uninterruptible power supply power management board, 113. Hard disk assembly, 114. Heat dissipation assembly, 115. Software system assembly, 116. Support frame, 117. Control cabinet B shell, 118. Control cabinet shaft, 119. Control cabinet A shell. DETAILED DESCRIPTION

[0019] The present invention provides a method and system for locating underwater manifold leakage based on dynamic pressure signals. By calculating the leakage characteristics of the collected dynamic pressure signals and correcting the pressure wave propagation velocity, accurate positioning of underwater manifold production system leakage is achieved, providing technical support for rapid response of leakage monitoring and ensuring the continuity of underwater production.

[0020] Specifically, the present invention provides a method for locating underwater manifold leakage based on dynamic pressure signals, such as Figure 1 As shown, the following steps are included: Step P1: Calculate the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions.

[0021] It should be pointed out that under different phase conditions in multiphase flow, the leakage characteristics of the dynamic pressure signal generated by the underwater manifold due to leakage are different, such as amplitude, frequency component, and energy. Therefore, in order to realize the signal processing of the dynamic pressure signal under multiphase flow medium conditions, it is first necessary to study the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions.

[0022] As a preferred embodiment of the present invention, the process of calculating the leakage characteristics of the dynamic pressure signal under the multiphase flow medium condition in step P1 is specifically described as follows: Step P101: Perform modal decomposition on the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions, and decompose it into multiple inherent modal functions.

[0023] Each intrinsic mode function represents a different component in the dynamic pressure signal and has different physical meanings. To facilitate understanding by those skilled in the art, an empirically based mode decomposition algorithm is provided as an example.

[0024] Table 1 shows the modal decomposition algorithm of dynamic pressure signal based on experience .

[0025] Step P102: Perform Hilbert-Huang transform on each intrinsic mode function to obtain the instantaneous frequency and instantaneous amplitude of each intrinsic mode function.

[0026] After completing step P101, a series of intrinsic modal functions (IMF) can be obtained. On this basis, step P102 is further implemented. As a preferred embodiment of the present invention, step P102 is specifically described as follows: The Hilbert-Huang transform of any intrinsic mode function c(t) satisfies: (1); In formula (1), c(t) represents the intrinsic mode function; P represents the Cauchy principal value; τ represents the time difference.

[0027] Among them, the analytical signal z(t) of the intrinsic mode function (it should be supplemented that the analytical signal z(t) of the intrinsic mode function is usually composed of the original signal and its Hilbert transform) further satisfies: (2); In formula (2), t represents time; A(t) represents the instantaneous amplitude of the intrinsic mode function c(t); represents the instantaneous phase of the intrinsic mode function c(t).

[0028] Instantaneous amplitude A(t) and instantaneous phase , respectively satisfying: (3); (4); For instantaneous phase Take the derivative and get the instantaneous frequency ,satisfy: (5).

[0029] Step P103: Perform weighted processing on the instantaneous amplitude and describe it in the time-frequency plane dimension to obtain the Hilbert spectrum of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow.

[0030] On the basis of completing step P102, further implement step P103. It should be noted that the leakage characteristics of the dynamic pressure signal are non-stationary; the corresponding leakage losses are different in the early, middle and late stages of the leakage. In addition, affected by the gas-liquid ratio of the two-phase flow, its characteristics will also change dynamically. Therefore, step P103 can effectively study the above dynamic changes through the Hilbert Spectrum and Hilbert Marginal Spectrum analysis process, obtain the time-frequency characteristics of the dynamic pressure signal, and reveal the main frequency components and energy distribution laws of the leakage characteristics of the dynamic pressure signal in different phases, which will help determine the operating status (evaluation) of the underwater manifold and locate the leakage point in the subsequent steps.

[0031] As a preferred embodiment of the present invention, the Hilbert spectrum of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow medium obtained in step P103 satisfies: (6); Further, by performing time integration processing on equation (6), the Hilbert yellow edge spectrum of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow medium is obtained (the Hilbert yellow edge spectrum represents the accumulation of amplitude over the entire time length; thus, it can reflect the amplitude change corresponding to each frequency), which satisfies: (7).

[0032] Step P104: Based on a statistical method, the amplitude characteristics of the pressure drop change rate in the leakage characteristics of the dynamic pressure signal generated by the leakage of fluids in different phases are analyzed.

[0033] On the basis of completing step P103, further implement step P104. It should be added that the most obvious change in the leakage characteristics is the change in the pressure value. The peak value and pressure difference value of the dynamic pressure signal generated by the leakage of fluids in different phases will be different. Therefore, studying its characteristics is of great significance for locating the leakage point in the subsequent steps. Here, the signal characteristics are mainly studied from the aspect of discreteness, and the evaluation index is selected as the pressure drop change rate.

[0034] Furthermore, the pressure drop change rate refers to the rate at which the pressure after leakage decreases relative to the original pressure after the fluid pressure drops due to leakage, which reflects the degree of fluid leakage. Due to the presence of external noise and other interference, when calculating the pressure drop change rate of the dynamic pressure signal, the average pressure value within a certain length of data points is selected to replace the pressure value before and after the leakage.

[0035] Specifically, as a preferred embodiment of the present invention, the pressure drop change rate in the leakage characteristic of the dynamic pressure signal generated by the leakage of fluids in different phases in step P104 satisfies: (8); In formula (8), r represents the voltage drop change rate; t represents time; x(t) represents the discrete time signal; and n represents the number of data points.

[0036] Step P2: Correct the propagation speed of the dynamic pressure signal under multiphase flow medium conditions.

[0037] After completing step P1, step P2 is further implemented. It is worth noting that since the propagation speed of the dynamic pressure signal (generated by the leak) has an important influence on the accuracy of leak point location, it is necessary to correct the propagation speed of the dynamic pressure signal under multiphase flow medium conditions before locating the leak point.

[0038] Specifically, as a more preferred implementation, the process of correcting the propagation velocity of the dynamic pressure signal under the multiphase flow medium condition in step P2 is specifically described as follows: The propagation speed of dynamic pressure signal under single-phase fluid medium conditions satisfies: (9); In formula (9), K represents the fluid bulk elastic modulus coefficient; ρ represents the fluid bulk density function.

[0039] Among them, the fluid bulk elastic modulus coefficient K satisfies: (10); In formula (10), α represents the compressibility coefficient; V represents the volume of the fluid medium; and dp represents the pressure.

[0040] According to the mass relationship, the fluid volume satisfies: (11).

[0041] Substituting formula (11) into formula (10), we get: (12).

[0042] Substituting equation (12) into equation (9), we obtain: (13).

[0043] Then, the propagation velocity of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow medium is further derived to satisfy: (14); In formula (14), K g Represents the bulk elastic modulus of the gas in the tube; K l Represents the bulk elastic modulus of the liquid in the tube; K a represents the bulk elastic modulus of the pipeline material; β represents the volumetric gas content of the gas-liquid two-phase flow; D represents the inner diameter of the pipeline; e represents the wall thickness of the pipeline; ρ l represents the density of the liquid in the tube; ρ g Indicates the density of the gas in the tube.

[0044] One point that needs to be supplemented is that, through the above correction steps, the calculation and correction of the propagation speed of the dynamic pressure signal of the liquid phase, gas-liquid two phases, and gas phase in the multiphase flow is realized. On this basis, the concept of gas-liquid flow ratio is further introduced to achieve the purpose of correcting the propagation speed of the dynamic pressure signal under the condition of multiphase flow medium.

[0045] Among them, the gas-liquid flow ratio refers to the ratio of the gas phase flow to the liquid phase flow, which satisfies: (15); In formula (15), q g Indicates the volume flow rate of gas in the pipe; q l Indicates the volume flow rate of liquid in the pipe.

[0046] Among them, the volume gas content satisfies: (16); In formula (16), V g Indicates the volume of gas in the tube; V l Indicates the volume of liquid in the tube.

[0047] The cross-sectional area of ​​the pipe in the underwater manifold is defined as A, then the flow velocity u of the gas phase and liquid phase in the fluid medium is g 、u l , respectively satisfying: (17).

[0048] The volumetric gas content in the tube within a certain time t is derived to satisfy: (18).

[0049] Then the relationship between volume gas content and gas-liquid flow ratio satisfies: (19).

[0050] Substituting equation (19) into equation (14), we obtain the propagation velocity correction formula of the dynamic pressure signal under multiphase flow medium conditions, which satisfies: (20); In formula (20), K g Represents the bulk elastic modulus of the gas in the tube; K l Represents the bulk elastic modulus of the liquid in the tube; K a represents the bulk elastic modulus of the pipeline material; β represents the gas-liquid ratio under multiphase flow medium conditions; D represents the inner diameter of the pipeline; e represents the wall thickness of the pipeline; ρ l represents the density of the liquid in the tube; ρ g Indicates the density of the gas in the tube.

[0051] Step P3: Calculate the location of underwater manifold leakage under multiphase flow medium conditions.

[0052] As a preferred embodiment of the present invention, the process of calculating the location of the underwater manifold leakage under the multiphase flow medium condition in step P3 can be specifically described as follows: Leak point location, meet: (27); In formula (27), X represents the leakage location; L represents the distance between the two sensors in the positioning network; v represents the propagation speed of the corrected dynamic pressure signal; Δt represents the time difference.

[0053] It is worth noting that due to the differences in fluid media in different phases, the reconstructed signal after filtering will still have a small amount of interference components, such as the influence of multiple working conditions such as starting and stopping the pump and frequency conversion. Therefore, the characteristics in the dynamic pressure signal generated by the sudden leakage will be submerged by other signals. In order to accurately and effectively capture this transient feature, it is necessary to further intercept the signal data during the sudden leakage.

[0054] Here, based on the interval correlation analysis method, the data segment in the dynamic pressure signal during leakage is extracted, and the cross-correlation peak analysis is performed to calculate the time difference Δt. The specific calculation steps can be referred to as follows: First, the dynamic pressure signal under multiphase flow medium conditions is extracted and divided into k intervals at equal intervals according to the time series x(t), and the data value x in each interval is obtained. i (t); where i=0,1,2,…,k.

[0055] Calculate the mean x in each interval i (t) avg . The mean value x of the latter interval i+1 (t) avg The average value x of the previous period i (t) avg Subtract and get the difference d i . The average value x in each interval is i (t) avg , the mean value x of the next interval i+1 (t) avg , difference d i , respectively satisfying: (28); (29); (30).

[0056] Find d i The maximum value index m of is the inflection point of the sudden instantaneous leakage. The maximum value index m satisfies: (31).

[0057] The data x(t) of the dynamic pressure signal when leakage occurs is extracted.

[0058] Based on the data x at both ends of the data x(t) 1 (t), x 2 (t), and find the peak value by combining the correlation analysis formula to calculate the time difference Δt.

[0059] Among them, the correlation analysis formula satisfies: (32); In formula (32), G 11 (f), G 22 (f) represents x 1 (t), x 2 (t) autocorrelation function; G 12 (f) represents x 1 (t), x 2 (t) is the cross-correlation function of

[0060] In addition, as a preferred embodiment of the present invention, the present invention provides an underwater manifold leakage locating method based on dynamic pressure signals, which further includes the following steps before implementing step P3: Step P30: Perform wavelet packet filtering preprocessing on the dynamic pressure signal under multiphase flow medium conditions.

[0061] It is worth noting that the use of wavelet packet filtering method to pre-process the dynamic pressure signal when a leak occurs can significantly distinguish between low-frequency components and high-frequency components, filter out high-frequency noise, improve the quality of leakage information, and thus enhance the signal recognizability.

[0062] Specifically, the denoising preprocessing method based on wavelet packet filtering can be referred to as follows: Assume that the original signal is S(0,0), S(n,j) represents the decomposition signal corresponding to the nth layer (i.e. the number of decomposition scales) and the jth node. Then, the dynamic pressure signal is decomposed by an n-layer wavelet packet, and its structure is as follows: Figure 2 As shown, Figure 2 The structure diagram of wavelet packet filter transform decomposition. The signal obtained by wavelet packet decomposition satisfies the following relationship: (twenty one); In (21), when the number of nodes j is an even number, it represents the low-frequency component signal obtained by decomposition by the low-pass filter coefficient g(k); conversely, when j is an odd number, it represents the high-frequency component signal obtained by decomposition by the high-pass filter coefficient h(k).

[0063] The high-pass and low-pass filter coefficients satisfy the following orthogonal relationship: (twenty two); Among them, the decomposed signal obtained at the nth decomposition layer can be obtained by calculating layer by layer according to equations (23) and (24).

[0064] (twenty three); (twenty four); According to the above decomposition method, after the signal is decomposed in the nth layer of wavelet packets, 2n decomposed signals will be obtained, and each decomposed signal corresponds to a certain frequency range. Assuming that the sampling frequency of the original signal is fs, the frequency range of the jth sub-signal decomposed in the nth layer can be expressed as [fl,fh], and the expressions of the frequency lower limit fl and upper limit fh can be expressed as: (25); (26); Combined with the time-frequency characteristic analysis of the dynamic pressure signal, the corresponding sub-signals of the wavelet packet decomposition are extracted and reconstructed according to the main frequency band occupied during leakage, so as to complete the denoising of the dynamic pressure signal.

[0065] Finally, one point that needs to be supplemented is that according to the pipeline where the leakage source is located based on the dynamic pressure signal, combined with the influence of factors such as phase change and gas content, the attenuation of pressure data makes it difficult to accurately identify the sensors at the beginning and end of the pipeline where the leakage source is located. The concept of short-time energy is selected here; among them, short-time energy is a time domain feature for analyzing the local characteristics of the signal, which can usually be used to capture the energy changes of the signal in a short time. By monitoring the instantaneous energy of the signal, its dynamic change process can be intuitively reflected (such as sudden leakage of the pipeline will cause a sudden drop in pressure), so analyzing the short-time energy of the dynamic pressure signal can effectively capture this transient feature. By framing the short-time energy in the dynamic pressure signal, a higher resolution can be provided in the time domain, and some interference noise can be further filtered out.

[0066] On the other hand, the present invention also provides an underwater manifold leakage locating system based on dynamic pressure signals. The underwater manifold leakage locating system based on dynamic pressure signals includes: a main control station and an underwater control module installed inside the basic frame of the underwater manifold.

[0067] Here, a master control station structure is provided as an example. Figure 3As shown, the specific structure of the master control station is a display 101, a keyboard 102, a touch pad 103, an industrial control mainboard 104, an impact-resistant corner 105, a control cabinet buckle 106, a portable handle 107, an uninterruptible power supply battery 108, a control cabinet C shell 109, a power carrier communication module host computer 110, an uninterruptible power supply AC-DC converter 111, an uninterruptible power supply power management board 112, a hard disk component 113, a heat dissipation component 114, a software system component 115, a support frame 116, a control cabinet B shell 117, a control cabinet shaft 118, and a control cabinet A shell 119. The uninterruptible power supply power management board 112 is connected to the uninterruptible power supply AC-DC converter 111, converting the external AC power provided by the platform umbilical cable terminal into stable DC power to provide suitable power for the internal components of the main control station; the uninterruptible power supply power management board 112 is connected to the uninterruptible power supply battery 108, which is used for the overall charging management, discharge control and status monitoring of the main control station, ensuring that the uninterruptible power supply battery 108 works in a safe and efficient state, and ensuring stable power supply when the external power supply is abnormal; the industrial control mainboard 104 is fixed to the support frame 116 by threaded connection, which is used to integrate the hardware components of the main control station and coordinate the work of various components, and is also used for dynamic pressure data reception and processing; the display 101, keyboard 102 and touchpad 103 constitute a human-machine interface for data monitoring display and control operation; the impact-resistant wrap angle 105, the control cabinet buckle 106, the portable handle 107, the control cabinet C shell 109, the control cabinet B shell 117, the control cabinet shaft 118, and the control cabinet A shell 119 together constitute a control cabinet for the main control station The internal components are arranged for installation and portable movement; the hard disk component 113 is used to store the system software and configuration files required for the operation of the main control station, record and save the collected data, operation logs, leakage information and other data, and provide data reading and writing services for data processing and analysis; the heat dissipation component 114 is connected to the industrial control mainboard 104, and is used to ensure the reliable operation of the industrial control mainboard 104 and the electronic components thereon through heat dissipation; the software system component 115 is used to realize data collection, processing, storage, and analysis of the entire system, and to perform equipment control and status monitoring; the support frame 116 is connected to the control cabinet B shell 117, and is used to firmly place the internal components of the main control station to ensure that the components work normally and stably under vibration, impact and other environments; the power carrier communication module host computer 110 is connected and fixed to the support frame 116 through a sliding guide rail, and is used to modulate the digital signal emitted by the main control station equipment into an analog signal transmitted by the power carrier, and at the same time demodulate the received analog signal into a digital signal, so as to realize data communication between the main control station and the underwater control module.

[0068] The underwater control module can refer to Figure 4 As shown, it includes a cabin structure, a dynamic pressure signal acquisition control instruction reading unit sealed in the cabin structure, a dynamic pressure signal acquisition unit and a power carrier communication lower computer.

[0069] Specifically, the underwater control module is installed inside the basic frame of the underwater manifold and is used to collect the (dynamic pressure) status data of the underwater manifold. The cabin structure is used to provide space and seal and protect other units in the underwater control module to ensure the stable operation of the underwater control module in the underwater environment. The dynamic pressure signal acquisition control instruction reading unit is used to receive control instructions. The dynamic pressure signal acquisition unit is used to collect and temporarily store the pressure data of the dynamic pressure signal. The power carrier communication lower computer is used to convert the collected data into a carrier signal and incorporate it into the transmission high voltage voltage.

[0070] In addition, it is optional to provide an end cover and a sealing structure for the cabin structure, so as to achieve the sealing of the cabin structure of the underwater control module. And it is further optional to provide a lifting structure and a through-cabin connection module at the end cover (the lifting structure is installed on the upper part of the end cover, and is used to lift and lower the entire underwater control box to complete the position movement; the through-cabin connection module is used to pass the communication cables, so as to facilitate the data transmission of the underwater control module). And, it is further preferred to provide a voltage step-down module, a centralized distribution module, and a power supply module in the underwater control module. Among them, the centralized distribution module is used to transmit electricity and collect data; the voltage step-down module is used to provide a suitable voltage; the power supply module is used to provide DC power supply for different needs.

[0071] And, as a more preferred embodiment of the present invention, the main control station also includes: a leakage positioning module. Figure 5 As shown, the leakage locating module includes: a dynamic pressure signal acquisition control instruction sending unit, a dynamic pressure signal receiving unit, a dynamic pressure signal storage unit, a dynamic pressure signal reading unit, a dynamic pressure signal noise reduction unit, a dynamic pressure signal processing unit, a leakage locating result transmission unit, a leakage locating result verification unit, and a leakage locating result display unit.

[0072] Among them, the dynamic pressure signal acquisition control instruction sending unit is used to send start and stop acquisition control instructions to the underwater control module; the dynamic pressure signal receiving unit is connected to the host computer of the power carrier communication module of the main control station, and is used to receive the signal data collected underwater; the dynamic pressure signal storage unit is connected to the dynamic pressure signal receiving unit, and is used to save temporary files and long-term storage data; the dynamic pressure signal reading unit is connected to the dynamic pressure signal storage unit, and is used to read the data required for the pressure signal; the dynamic pressure signal noise reduction unit and the dynamic pressure signal processing unit are connected to each other, and are used to reduce the noise of the dynamic pressure signal and perform leakage location detection on the underwater manifold; the leakage location result transmission unit is connected to the dynamic pressure signal processing unit, and is used to integrate and transmit the results obtained by the dynamic pressure signal processing unit; the leakage location result verification unit is used to judge the validity of the positioning result obtained by the dynamic pressure signal processing unit; the leakage location result display unit is connected to the leakage location result verification unit, and is used to display the valid leakage location result.

[0073] The present invention provides a method and system for locating underwater manifold leakage based on dynamic pressure signals. The method for locating underwater manifold leakage includes the following steps: step P1: calculating the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions; step P2: correcting the propagation speed of the dynamic pressure signal under multiphase flow medium conditions; step P3: performing leakage location calculation on the underwater manifold under multiphase flow medium conditions.

[0074] The present invention provides a method and system for locating underwater manifold leakage based on dynamic pressure signals, which has at least the following technical advantages compared with the prior art: (1) This underwater manifold leakage location method and system collects the dynamic pressure signal under the multiphase flow medium condition in the underwater manifold pipeline; and after extracting the leakage characteristics, it realizes the rapid response location calculation of the underwater manifold leakage. The leakage location result is real-time and reliable, which helps to realize the real-time monitoring of underwater manifold leakage and provides technical support for ensuring the continuity of underwater manifold production; (2) This underwater manifold leakage locating method and system adopts the technical means of calculating the leakage characteristics of the dynamic pressure signal under the condition of multiphase flow medium and correcting the propagation speed of the dynamic pressure signal under the condition of multiphase flow medium, which effectively improves the accuracy of the leakage locating results and provides help for technical personnel to reveal the operating status of the underwater manifold under different phase media and grasp the specific location of the leakage point.

[0075] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for locating underwater manifold leakage based on dynamic pressure signals, characterized in that: The steps include: Step P1: Calculate the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions; Step P2: Correcting the propagation velocity of the dynamic pressure signal under multiphase flow medium conditions; Step P3: Calculate the leakage location of the underwater manifold under multiphase flow medium conditions; The process of calculating the leakage characteristics of the dynamic pressure signal under the multiphase flow medium condition in step P1 is specifically described as follows: Step P101: performing modal decomposition on the leakage characteristics of the dynamic pressure signal under the multiphase flow medium condition, and decomposing it into multiple inherent modal functions; Step P102: performing Hilbert-Huang transform on each intrinsic mode function to obtain the instantaneous frequency and instantaneous amplitude of each intrinsic mode function; Step P103: weighting the instantaneous amplitude and describing it in the time-frequency plane dimension to obtain the Hilbert spectrum of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow; Step P104: Based on a statistical method, the amplitude characteristics of the pressure drop change rate in the leakage characteristics of the dynamic pressure signal generated by the leakage of fluids in different phases are analyzed.

2. The underwater manifold leakage locating method based on dynamic pressure signal according to claim 1 is characterized in that: The step P102 is specifically described as: The Hilbert-Huang transform of any intrinsic mode function c(t) satisfies: （1）； In formula (1), c(t) represents the intrinsic mode function; P represents the Cauchy principal value; τ represents the time difference; Among them, the analytical signal z(t) of the intrinsic mode function further satisfies: （2）； In formula (2), t represents time; A(t) represents the instantaneous amplitude of the intrinsic mode function c(t); represents the instantaneous phase of the intrinsic mode function c(t); Instantaneous amplitude A(t) and instantaneous phase , respectively satisfying: （3）； （4）； For instantaneous phase Take the derivative and get the instantaneous frequency ,satisfy: （5）。 3. The underwater manifold leakage locating method based on dynamic pressure signal according to claim 1 is characterized in that: The Hilbert spectrum of the dynamic pressure signal under the gas-liquid two-phase intermittent flow condition obtained in step P103 satisfies: （6）； Further, by performing time integration on equation (6), the Hilbert yellow edge spectrum of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow medium is obtained, which satisfies: （7）。 4. The underwater manifold leakage locating method based on dynamic pressure signal according to claim 1, characterized in that: The amplitude characteristic of the pressure drop change rate in the leakage characteristic of the dynamic pressure signal generated by the leakage of fluids in different phases in step P104 satisfies: （8）； In formula (8), r represents the voltage drop change rate; t represents time; x(t) represents the discrete time signal; and n represents the number of data points.

5. The underwater manifold leakage locating method based on dynamic pressure signal according to claim 1, characterized in that: The process of correcting the propagation velocity of the dynamic pressure signal under the multiphase flow medium condition in step P2 is specifically described as follows: The propagation speed of the dynamic pressure signal under single-phase fluid medium conditions satisfies: （9）； In formula (9), K represents the fluid bulk elastic modulus coefficient; ρ represents the fluid bulk density function; Among them, the fluid bulk elastic modulus coefficient K satisfies: （10）； In formula (10), α represents the compressibility coefficient; V represents the volume of the fluid medium; dp represents the pressure; According to the mass relationship, the fluid volume satisfies: （11）； Substituting formula (11) into formula (10), we get: （12）； Substituting equation (12) into equation (9), we get: （13）； The propagation velocity of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow medium is further derived to satisfy: （14）； In formula (14), K g Represents the bulk elastic modulus of the gas in the tube; K l Represents the bulk elastic modulus of the liquid in the tube; K a represents the bulk elastic modulus of the pipeline material; β represents the volumetric gas content of the gas-liquid two-phase flow; D represents the inner diameter of the pipeline; e represents the wall thickness of the pipeline; ρ l represents the density of the liquid in the tube; ρ g Indicates the density of gas in the tube; The gas-liquid flow ratio is introduced; the gas-liquid flow ratio refers to the ratio of the gas phase flow to the liquid phase flow, which satisfies: （15）； In formula (15), q g Indicates the volume flow rate of gas in the pipe; q l Indicates the volume flow rate of the liquid in the pipe; Among them, the volume gas content satisfies: （16）； In formula (16), V g Indicates the volume of gas in the tube; V l Indicates the volume of liquid in the tube; The cross-sectional area of ​​the pipe in the underwater manifold is defined as A, then the flow velocity u of the gas phase and liquid phase in the fluid medium is g 、u l , respectively satisfying: （17）； The volumetric gas content in the tube within a certain time t is derived to satisfy: （18）； Then the relationship between volume gas content and gas-liquid flow ratio satisfies: （19）； Substituting equation (19) into equation (14), we obtain the propagation velocity correction formula of the dynamic pressure signal under multiphase flow medium conditions, which satisfies: （20）； In formula (20), K g Represents the bulk elastic modulus of the gas in the tube; K l Represents the bulk elastic modulus of the liquid in the tube; K a represents the bulk elastic modulus of the pipeline material; β represents the gas-liquid ratio under multiphase flow medium conditions; D represents the inner diameter of the pipeline; e represents the wall thickness of the pipeline; ρ l represents the density of the liquid in the tube; ρ g Indicates the density of the gas in the tube.

6. The underwater manifold leakage locating method based on dynamic pressure signals according to claim 1, characterized in that: The process of calculating the leakage location of the underwater manifold under the multiphase flow medium condition in step P3 is specifically described as: leakage point location, satisfying: （27）； In formula (27), X represents the leakage location; L represents the distance between the two sensors in the positioning network; v represents the propagation speed of the corrected dynamic pressure signal; Δt represents the time difference.

7. The underwater manifold leakage locating method based on dynamic pressure signals according to claim 1, characterized in that: Before implementing step P3, the following steps are also included: Step P30: Perform wavelet packet filtering preprocessing on the dynamic pressure signal under multiphase flow medium conditions.

8. The underwater manifold leakage location system based on dynamic pressure signal is characterized by: The underwater manifold leakage locating system adopts the underwater manifold leakage locating method according to any one of claims 1 to 7, and comprises: a main control station, and an underwater control module installed inside the basic frame of the underwater manifold; The master control station includes: a power carrier communication module host computer, an industrial control mainboard and a display; The underwater control module includes: a cabin structure, a dynamic pressure signal acquisition control instruction reading unit, a dynamic pressure signal acquisition unit and a power carrier communication lower computer which are sealed and arranged in the cabin structure; Among them, through the power cable in the umbilical cable, a communication connection is established between the power carrier communication module host computer and the power carrier communication slave computer.

9. The underwater manifold leakage locating system based on dynamic pressure signals according to claim 8, characterized in that: The main control station also includes: a leakage locating module; The leakage locating module includes: a dynamic pressure signal acquisition control instruction sending unit, a dynamic pressure signal receiving unit, a dynamic pressure signal storage unit, a dynamic pressure signal reading unit, a dynamic pressure signal noise reduction unit, a dynamic pressure signal processing unit, a leakage locating result transmission unit, a leakage locating result verification unit, and a leakage locating result display unit.

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