Underwater Manifold Leak Location Method and System Based on Dynamic Pressure Signals

Abstract

The present invention belongs to the technical field of petroleum engineering, and particularly relates to a method and system for underwater pipeline leakage location based on dynamic pressure signals. The method and system for underwater pipeline leakage location based on dynamic pressure signals achieve precise location of leakage in the underwater pipeline production system by calculating the leakage characteristics of the collected dynamic pressure signals and correcting the pressure wave propagation speed, providing technical support for realizing rapid response of leakage monitoring and ensuring the continuity of underwater production. The present invention provides a method for underwater pipeline leakage location based on dynamic pressure signals, including the following steps: Step P1: Calculate the leakage characteristics of the dynamic pressure signals under multiphase flow medium conditions; Step P2: Correct the propagation speed of the dynamic pressure signals under multiphase flow medium conditions; Step P3: Perform leakage location calculation on the underwater pipeline under multiphase flow medium conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of petroleum engineering, and particularly relates to a method and system for underwater pipeline leakage location based on dynamic pressure signals. Background Art

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

[0003] After further research, it is found that a pressure wave sensor or other sensing devices can be used to monitor the dynamic pressure (fluctuation) signals generated by the leakage of the internal fluid of underwater pipelines; and when there is an abnormal rapid decrease or fluctuation in pressure, the possible leakage phenomenon of underwater pipelines can be judged and identified. In addition, by installing multiple pressure sensing devices at different positions, based on the time difference of the pressure wave reaching each sensing device, the specific position of the leakage point can be calculated based on time reversal or other algorithms.

[0004] However, the inventor found that the pipeline structure of existing underwater pipelines in service is very complex (with support structures, anti-fishing nets and other protection devices integrated outside), and the underwater environment is changeable and noisy, which brings great difficulties 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 method and system for underwater pipeline leakage location to realize online monitoring and accurate location of underwater pipeline leakage, so as to quickly respond to potential leakage events and provide help for ensuring the safe and efficient development of oil and gas production. Summary of the Invention

[0005] The present invention provides a method and system for underwater pipeline leakage location based on dynamic pressure signals. Among them, by calculating the leakage characteristics of the collected dynamic pressure signals and correcting the pressure wave propagation speed, the accurate location of the leakage of the underwater pipeline production system is realized, providing technical support for realizing the rapid response of leakage monitoring and ensuring the continuity of underwater production.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The method for underwater pipeline leakage location based on dynamic pressure signals includes the following steps:

[0008] Step P1: Calculate the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions;

[0009] Step P2: Correct the propagation speed of the dynamic pressure signal under multiphase flow medium conditions;

[0010] Step P3: Perform leakage location calculation on the underwater pipeline under multiphase flow medium conditions.

[0011] More preferably, the process of calculating the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions in step P1 is specifically described as:

[0012] Step P101: Decompose the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions by modal decomposition into multiple intrinsic mode functions;

[0013] Step P102: Perform Hilbert-Huang transform on each intrinsic mode function to obtain the instantaneous frequency and instantaneous amplitude of each intrinsic mode function;

[0014] 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 gas-liquid two-phase intermittent flow conditions;

[0015] Step P104: Based on statistical methods, analyze 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.

[0016] More preferably, step P102 is specifically described as:

[0017] The Hilbert-Huang transform of any intrinsic mode function c(t) satisfies:

[0018] (1);

[0019] In formula (1), c(t) represents the intrinsic mode function; P represents the Cauchy principal value; τ represents the time difference;

[0020] Among them, the analytic signal z(t) of the intrinsic mode function further satisfies:

[0021] (2);

[0022] 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);

[0023] The instantaneous amplitude A(t) and the instantaneous phase , respectively satisfy:

[0024] (3);

[0025] (4);

[0026] Derive the instantaneous phase to obtain the instantaneous frequency , satisfying:

[0027] (5).

[0028] More preferably, the Hilbert spectrum of the dynamic pressure signal under the gas-liquid two-phase intermittent flow condition obtained in step P103 satisfies:

[0029] (6);

[0030] Further, perform time integration on equation (6) to obtain the Hilbert-Huang marginal spectrum of the dynamic pressure signal under the gas-liquid two-phase intermittent flow medium condition, satisfying:

[0031] (7).

[0032] More preferably, the amplitude characteristic of the pressure drop change rate in the leakage characteristics of the dynamic pressure signal generated by the leakage of fluids in different phases in step P104 satisfies:

[0033] (8);

[0034] In equation (8), r represents the pressure drop change rate; t represents time; x(t) represents the discrete time signal; n represents the number of data point teams.

[0035] More preferably, the process of correcting the propagation speed of the dynamic pressure signal under the multiphase flow medium condition in step P2 is specifically described as:

[0036] The propagation speed of the dynamic pressure signal under the single-phase fluid medium condition satisfies:

[0037] (9);

[0038] In equation (9), K represents the fluid bulk modulus coefficient; ρ represents the fluid volume density function;

[0039] Among them, the fluid bulk modulus coefficient K satisfies:

[0040] (10);

[0041] In equation (10), α represents the compressibility coefficient; V represents the fluid medium volume; dp represents the pressure;

[0042] According to the mass relationship, the fluid volume satisfies:

[0043] (11);

[0044] Substituting Equation (11) into Equation (10), we get:

[0045] (12);

[0046] Substituting Equation (12) into Equation (9), we get:

[0047] (13);

[0048] Further derivation gives the propagation speed of the dynamic pressure signal under the conditions of gas-liquid two-phase intermittent flow medium, satisfying:

[0049] (14);

[0050] In Equation (14), K g represents the bulk modulus of elasticity of the gas in the pipe; K l represents the bulk modulus of elasticity of the liquid in the pipe; K a represents the bulk modulus of elasticity of the pipeline material; β represents the gas volume fraction in the gas-liquid two-phase flow; D represents the inner diameter of the pipeline; e represents the pipeline wall thickness; ρ l represents the density of the liquid in the pipe; ρ g represents the density of the gas in the pipe;

[0051] The gas-liquid flow rate ratio is introduced; where the gas-liquid flow rate ratio is the ratio of the gas flow rate to the liquid flow rate, satisfying:

[0052] (15);

[0053] In Equation (15), q g represents the volume flow rate of the gas in the pipe; q l represents the volume flow rate of the liquid in the pipe;

[0054] Among them, the gas volume fraction satisfies:

[0055] (16);

[0056] In Equation (16), V g represents the volume of the gas in the pipe; V l represents the volume of the liquid in the pipe;

[0057] Define the cross-sectional area of the pipeline in the subsea manifold as A, then the flow velocities u g and u l of the gas phase and liquid phase in the fluid medium respectively satisfy:

[0058] (17);

[0059] The volume gas holdup in the pipe within a certain time t is derived and satisfies:

[0060] (18);

[0061] Then, the relationship between the volume gas holdup and the gas-liquid flow ratio satisfies:

[0062] (19);

[0063] Substituting Equation (19) into Equation (14), the propagation speed correction formula for the dynamic pressure signal under the multiphase flow medium condition is obtained and satisfies:

[0064] (20);

[0065] In Equation (20), K g represents the volume elastic modulus of the gas in the pipe; K l represents the volume elastic modulus of the liquid in the pipe; K a represents the volume elastic modulus of the pipeline material; β represents the gas-liquid ratio under the multiphase flow medium condition; D represents the inner diameter of the pipeline; e represents the pipeline wall thickness; ρ l represents the density of the liquid in the pipe; ρ g represents the density of the gas in the pipe.

[0066] More preferably, the process of performing leakage location calculation on the underwater pipeline network under the multiphase flow medium condition in step P3 is specifically described as: The leakage point location satisfies:

[0067] (27);

[0068] In Equation (27), X represents the leakage position; L represents the distance between two sensors in the positioning network; v represents the propagation speed of the corrected dynamic pressure signal; Δt represents the time difference.

[0069] More preferably, before implementing step P3, the following steps are further included:

[0070] Step P30: Perform wavelet packet filtering preprocessing on the dynamic pressure signal under the multiphase flow medium condition.

[0071] On the other hand, the present invention also provides an underwater pipeline network leakage location system based on dynamic pressure signals, including: a main control station, and an underwater control module installed inside the basic framework of the underwater pipeline network;

[0072] The main control station includes: a power line carrier communication module host computer, an industrial control main board, and a display;

[0073] The underwater control module includes: a cabin structure, and a dynamic pressure signal acquisition and control instruction reading unit, a dynamic pressure signal acquisition unit, and a power line carrier communication lower computer that are hermetically arranged within the cabin structure;

[0074] Among them, through the power cable in the umbilical cable, communication interconnection is established between the power line carrier communication upper computer and the power line carrier communication lower computer.

[0075] More preferably, the master control station further includes: a leakage positioning module;

[0076] The leakage positioning module includes: a dynamic pressure signal acquisition and 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 positioning result transmission unit, a leakage positioning result verification unit, and a leakage positioning result display unit.

[0077] The present invention provides an underwater pipeline leak positioning method and system based on dynamic pressure signals. Among them, in the underwater pipeline leak positioning method, the following steps are included: Step P1: Calculate the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions; Step P2: Correct the propagation speed of the dynamic pressure signal under multiphase flow medium conditions; Step P3: Perform leakage positioning calculation on the underwater pipeline under multiphase flow medium conditions.

[0078] An underwater pipeline leak positioning method and system based on dynamic pressure signals provided by the present invention, compared with the prior art, at least has the following technical advantages:

[0079] (1) This underwater pipeline leak positioning method and system collect the dynamic pressure signal under multiphase flow medium conditions in the underwater pipeline; and after extracting the leakage characteristics therein, rapid response positioning calculation for underwater pipeline leakage is realized. The leakage positioning result is real-time and reliable, which helps to realize the real-time monitoring of underwater pipeline leakage and provides technical support for ensuring the continuity of underwater pipeline production;

[0080] (2) This underwater pipeline leak positioning method and system adopt technical means such as calculating the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions and correcting the propagation speed of the dynamic pressure signal under multiphase flow medium conditions, effectively improving the accuracy of the leakage positioning result, and helping technicians to reveal the operating state of the underwater pipeline under different phase state media and master the specific positioning of the leakage point. Brief Description of the Drawings

[0081] 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 to the present invention. In the following drawings:

[0082] Figure 1 It is a schematic flow chart of the underwater pipeline leak location method based on dynamic pressure signals provided by the present invention;

[0083] Figure 2 It is a schematic diagram of the wavelet packet filter transform decomposition structure during the wavelet packet filtering preprocessing of dynamic pressure signals under multiphase flow medium conditions;

[0084] Figure 3 It is a schematic diagram of the structure of the main control station in the underwater pipeline leak location system based on dynamic pressure signals provided by the present invention;

[0085] Figure 4 It is an electrical structure block diagram of the underwater control module in the main control station;

[0086] Figure 5 It is an electrical structure block diagram of the leak location module in the underwater pipeline leak location system based on dynamic pressure signals provided by the present invention;

[0087] Reference numerals:

[0088] 101, display; 102, keyboard; 103, touchpad; 104, industrial control main board; 105, anti-impact corner; 106, control cabinet buckle; 107, portable handle; 108, uninterruptible power supply battery; 109, control cabinet C shell; 110, power line 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 rotating shaft; 119, control cabinet A shell. Detailed implementation manners

[0089] The present invention provides an underwater pipeline leak location method and system based on dynamic pressure signals. Among them, by calculating the leak characteristics of the collected dynamic pressure signals and correcting the pressure wave propagation speed, the accurate location of the leak in the underwater pipeline production system is realized, providing technical support for achieving a rapid response to leak monitoring and ensuring the continuity of underwater production.

[0090] Specifically, the present invention provides an underwater pipeline leak location method based on dynamic pressure signals, as Figure 1 shown, including the following steps:

[0091] Step P1: Calculate the leak characteristics of the dynamic pressure signals under multiphase flow medium conditions.

[0092] It should be noted that under different phase conditions in multiphase flow, the leakage characteristics such as the amplitude, frequency components, and energy of the dynamic pressure signal generated by the underwater pipeline due to leakage are different. Therefore, in order to perform signal processing on 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.

[0093] As a relatively preferred embodiment of the present invention, the process of calculating the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions in step P1 is specifically described as follows:

[0094] Step P101: Perform modal decomposition on the leakage characteristics of the dynamic pressure signal under multiphase flow medium conditions, and decompose it into multiple intrinsic mode functions.

[0095] Among them, each intrinsic mode function represents different components in the dynamic pressure signal and has different physical meanings. For the convenience of those skilled in the art to understand, an empirical-based modal decomposition algorithm is provided here as an example.

[0096] Table 1 is the modal decomposition algorithm of the dynamic pressure signal based on experience

[0097] .

[0098] Step P102: Perform Hilbert-Huang transform on each intrinsic mode function to obtain the instantaneous frequency and instantaneous amplitude of each intrinsic mode function.

[0099] After completing step P101, a series of intrinsic mode functions (English: Intrinsic Modal Function, IMF) can be obtained. On this basis, step P102 is further implemented. As a relatively preferred embodiment of the present invention, this step P102 is specifically described as follows:

[0100] The Hilbert-Huang transform of any intrinsic mode function c(t) satisfies:

[0101] (1);

[0102] In formula (1), c(t) represents the intrinsic mode function; P represents the Cauchy principal value; τ represents the time difference.

[0103] Among them, the analytic signal z(t) of the intrinsic mode function (it should be added that the analytic signal z(t) of this intrinsic mode function is usually composed of the original signal and its Hilbert transform) further satisfies:

[0104] (2);

[0105] In Equation (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).

[0106] The instantaneous amplitude A(t) and the instantaneous phase , respectively satisfy:

[0107] (3);

[0108] (4);

[0109] Derive the instantaneous phase to obtain the instantaneous frequency , which satisfies:

[0110] (5).

[0111] 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.

[0112] On the basis of completing Step P102, Step P103 is further implemented. It should be noted that the leakage characteristics of the dynamic pressure signal are non-stationary; in the initial, middle, and late stages of leakage occurrence, the corresponding leakage losses are different from each other. In addition, affected by the gas-liquid ratio of the two-phase flow, its characteristics will also change dynamically. Therefore, through the HilbertSpectrum and Hilbert Marginal Spectrum analysis processes in Step P103, the above dynamic changes can be effectively studied, the time-frequency characteristics of the dynamic pressure signal can be obtained, and the main frequency components and energy distribution laws of the leakage characteristics of the dynamic pressure signal in different phases can be revealed, providing help for determining the operating state (evaluation) of the underwater pipeline network and locating the leakage point in the subsequent steps.

[0113] As a relatively preferred implementation manner of the present invention, the Hilbert spectrum of the dynamic pressure signal under the condition of the gas-liquid two-phase intermittent flow medium obtained in Step P103 satisfies:

[0114] (6);

[0115] Further perform time integration processing on Equation (6) to obtain the Hilbert-Huang marginal spectrum of the dynamic pressure signal under the condition of the gas-liquid two-phase intermittent flow medium (the Hilbert-Huang marginal spectrum represents the cumulative amplitude over the entire time length; thereby, it can reflect the amplitude change corresponding to each frequency), which satisfies:

[0116] (7).

[0117] Step P104: Analyze the amplitude characteristics of the pressure drop change rate in the leakage characteristics of the dynamic pressure signals generated by the leakage of fluids in different phases based on statistical methods.

[0118] On the basis of completing Step P103, Step P104 is further implemented. It should be added that the most obvious change in the leakage characteristics is the change in the pressure value. The peak value and the pressure difference value of the dynamic pressure signals generated by the leakage of fluids in different phases will vary. Therefore, studying its characteristics is of great significance for the subsequent leakage point positioning. Here, the signal characteristics are mainly studied from the aspect of the degree of dispersion, and the evaluation index is selected as the pressure drop change rate.

[0119] Furthermore, the pressure drop change rate refers to the rate of decrease of the pressure after leakage relative to the original pressure when the fluid pressure decreases due to leakage, which reflects the degree of fluid leakage. Due to the interference of external noise and the like, 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 values before and after leakage.

[0120] Specifically, as a relatively preferred implementation manner of the present invention, the pressure drop change rate in the leakage characteristics of the dynamic pressure signals generated by the leakage of fluids in different phases in Step P104 satisfies:

[0121] (8);

[0122] In formula (8) thereof, r represents the pressure drop change rate; t represents time; x(t) represents the discrete time signal; n represents the number of data point teams.

[0123] Step P2: Correct the propagation speed of the dynamic pressure signal under the condition of multiphase flow medium.

[0124] On the basis of completing Step P1, Step P2 is further implemented. It should be noted that since the propagation speed of the (leakage-generated) dynamic pressure signal has an important impact on the accuracy of leakage point positioning, before positioning the leakage point, it is also necessary to correct the propagation speed of the dynamic pressure signal under the condition of multiphase flow medium.

[0125] Specifically, as a relatively preferred implementation manner, the process of correcting the propagation speed of the dynamic pressure signal under the condition of multiphase flow medium in Step P2 is specifically described as:

[0126] The propagation speed of the dynamic pressure signal under the condition of single-phase fluid medium satisfies:

[0127] (9);

[0128] In formula (9), K represents the fluid volume elastic modulus coefficient; ρ represents the fluid volume density function.

[0129] Among them, the fluid bulk modulus coefficient K satisfies:

[0130] (10);

[0131] In Equation (10), α represents the compressibility coefficient; V represents the volume of the fluid medium; dp represents the pressure.

[0132] According to the mass relationship, the fluid volume satisfies:

[0133] (11).

[0134] Substituting Equation (11) into Equation (10), we get:

[0135] (12).

[0136] Substituting Equation (12) into Equation (9), we get:

[0137] (13).

[0138] Then, further derivation is carried out to obtain that the propagation speed of the dynamic pressure signal under the condition of gas-liquid two-phase intermittent flow medium satisfies:

[0139] (14);

[0140] In Equation (14), K g represents the bulk modulus of the gas in the pipe; K l represents the bulk modulus of the liquid in the pipe; K a represents the bulk modulus of the pipeline material; β represents the gas volume fraction in the gas-liquid two-phase flow; D represents the inner diameter of the pipeline; e represents the pipeline wall thickness; ρ l represents the density of the liquid in the pipe; ρ g represents the density of the gas in the pipe.

[0141] It should be supplemented and explained that through the above correction steps, the calculation correction of the propagation speed of the dynamic pressure signal in the liquid phase, gas-liquid two-phase, 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.

[0142] Among them, the gas-liquid flow ratio refers to the ratio of the gas flow rate to the liquid flow rate and satisfies:

[0143] (15);

[0144] In Equation (15), q g represents the volume flow rate of the gas in the pipe; ql Represents the volumetric flow rate of the liquid in the pipe.

[0145] Among them, the volume gas holdup satisfies:

[0146] (16);

[0147] In formula (16), V g Represents the volume of gas in the pipe; V l Represents the volume of liquid in the pipe.

[0148] Define the cross-sectional area of the pipeline in the subsea manifold as A, then the flow velocities u g 、u l of the gas phase and liquid phase in the fluid medium respectively satisfy:

[0149] (17).

[0150] It is derived that the volume gas holdup in the pipe within a certain time t satisfies:

[0151] (18).

[0152] Then the relationship between the volume gas holdup and the gas-liquid flow ratio satisfies:

[0153] (19).

[0154] Substitute formula (19) into formula (14) to obtain the propagation speed correction formula of the dynamic pressure signal under the condition of multiphase flow medium, which satisfies:

[0155] (20);

[0156] In formula (20), K g Represents the volume elastic modulus of the gas in the pipe; K l Represents the volume elastic modulus of the liquid in the pipe; K a Represents the volume elastic modulus of the pipeline material; β represents the gas-liquid ratio under the condition of multiphase flow medium; 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 pipe; ρ g Represents the density of the gas in the pipe.

[0157] Step P3: Perform localization calculation on the leakage of the subsea manifold under the condition of multiphase flow medium.

[0158] As a relatively preferred implementation manner of the present invention, the process of performing localization calculation on the leakage of the subsea manifold under the condition of multiphase flow medium in step P3 can be specifically described as:

[0159] Leak point localization satisfies:

[0160] (27);

[0161] In formula (27), X represents the leakage position; L represents the distance between two sensors in the positioning network; v represents the propagation speed of the corrected dynamic pressure signal; Δt represents the time difference.

[0162] It should be noted that due to the differences in fluid media of different phases, there will still be a small number of interference components in the filtered reconstructed signal, such as the influence of multiple working conditions such as starting and stopping pumps and frequency conversion. Therefore, the characteristics in the dynamic pressure signal generated by sudden leakage will be submerged by other signals. In order to accurately and effectively capture this transient characteristic, it is necessary to further intercept the signal data during sudden leakage.

[0163] Here, based on the interval correlation analysis method, the data segment in the dynamic pressure signal during leakage is extracted, and its cross-correlation peak analysis is performed to calculate the time difference Δt. The specific calculation steps can be referred to as follows:

[0164] First, extract the dynamic pressure signal under the condition of multiphase flow medium, and divide it into k intervals at equal intervals according to the time series x(t) to obtain the data values x i (t); where i = 0, 1, 2,..., k.

[0165] Calculate the average value x i (t) avg . Subtract the average value x i+1 (t) avg of the latter interval from the average value x i (t) avg of the previous segment to obtain the difference d i . Among them, the average value x i (t) avg in each interval, the average value x i+1 (t) avg of the latter interval, and the difference d i respectively satisfy:

[0166] (28);

[0167] (29);

[0168] (30).

[0169] Find the maximum value index m of d i . The position where the maximum value index m is located is the inflection point of sudden instantaneous leakage. Among them, the maximum value index m satisfies: (31).

[0170] Extract the data x(t) of the dynamic pressure signal when leakage occurs.

[0171] Based on the data x1(t) and x2(t) at the beginning and end of the data x(t), the peak value is found by combining the correlation analysis formula, and thus the time difference Δt is calculated.

[0172] Among them, the correlation analysis formula satisfies:

[0173] (32);

[0174] In formula (32), G 11 (f) and G 22 (f) respectively represent the autocorrelation functions of x1(t) and x2(t); G 12 (f) represents the cross-correlation function of x1(t) and x2(t).

[0175] In addition, as a more preferred embodiment of the present invention, a method for locating underwater pipeline leakage based on dynamic pressure signals provided by the present invention further includes the following steps before implementing step P3:

[0176] Step P30: Perform wavelet packet filtering preprocessing on the dynamic pressure signal under multiphase flow medium conditions.

[0177] It should be noted that using the wavelet packet filtering method to preprocess the dynamic pressure signal when leakage occurs can significantly distinguish low-frequency components from high-frequency components, filter out high-frequency noise, improve the quality of leakage information, and thus enhance the signal's recognizability.

[0178] Specifically, the process flow of the noise reduction preprocessing method based on wavelet packet filtering can be referred to as follows: Assume the original signal is S(0,0), and S(n,j) represents the decomposed signal corresponding to the nth layer (i.e., the decomposition scale number) and the jth node. Then, perform n-layer wavelet packet decomposition on the dynamic pressure signal, and its structure is as Figure 2 shown, Figure 2 which is a schematic diagram of the structure of wavelet packet filtering transformation decomposition. Among them, the signal obtained by wavelet packet decomposition satisfies the following relationship:

[0179] (21);

[0180] In formula (21), when the node number j is even, it represents the low-frequency component signal decomposed by the low-pass filter coefficient g(k); conversely, when j is odd, it represents the high-frequency component signal decomposed by the high-pass filter coefficient h(k).

[0181] The high-pass and low-pass filter coefficients satisfy the following orthogonal relationship:

[0182] (22);

[0183] Among them, the decomposed signal obtained at the nth decomposition layer can be obtained through layer-by-layer calculation according to formulas (23) and (24).

[0184] (23);

[0185] (24);

[0186] Decomposed in the above manner, after the wavelet packet decomposition of the signal at the nth layer, 2^n decomposed signals will be obtained, and each decomposed signal corresponds to a certain frequency interval. Assuming that the sampling frequency of the original signal is fs, for the jth sub-signal of the nth layer decomposition, its frequency segment interval can be expressed as [fl, fh], and the expressions for the lower frequency limit fl and the upper frequency limit fh can be respectively expressed as:

[0187] (25);

[0188] (26);

[0189] Combined with the time-frequency characteristic analysis of the dynamic pressure signal, according to the main frequency band occupied during leakage, the corresponding sub-signal of the wavelet packet decomposition is extracted for reconstruction, and the noise reduction of the dynamic pressure signal can be completed.

[0190] Finally, it should be added that according to the pipeline where the leakage source is located determined by the dynamic pressure signal, considering the influence of factors such as phase change and gas holdup, it is difficult to accurately identify the sensors at the head and end of the pipeline where the leakage source is located due to the attenuation of pressure data. Here, the concept of short-time energy is selected; among them, short-time energy is a time-domain feature for analyzing the local characteristics of a signal and is usually used to capture the energy change of a signal within a short time. By monitoring the instantaneous energy of the signal, its dynamic change process can be intuitively reflected (such as a sudden leakage in 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 performing frame-by-frame processing on the short-time energy in the dynamic pressure signal, a higher resolution can be provided in the time domain, and some interference noises can be further filtered out.

[0191] On the other hand, the present invention also provides an underwater pipeline leakage positioning system based on dynamic pressure signals. The underwater pipeline leakage positioning system based on dynamic pressure signals includes: a master control station, and an underwater control module installed inside the basic framework of the underwater pipeline.

[0192] Here, a master control station structure is provided as an example. Specifically, refer to Figure 3As shown in the figure, the specific structure of the master control station includes a display 101, a keyboard 102, a touchpad 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 line 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 rotating 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 to convert the external alternating current provided by the platform umbilical cable terminal into stable direct current, providing appropriate power for the internal components of the master control station; the uninterruptible power supply power management board 112 is connected to the uninterruptible power supply battery 108 for overall charging management, discharge control, and status monitoring of the master control station, ensuring that the uninterruptible power supply battery 108 works in a safe and efficient state and guaranteeing stable power supply in case of abnormal external power supply; the industrial control mainboard 104 is fixed on the support frame 116 by threaded connection, used to integrate the hardware components of the master control station and coordinate the work of each component, and is also used for receiving and processing dynamic pressure data; the display 101, the keyboard 102, and the touchpad 103 constitute a human-machine interface for data monitoring display and control operations; the impact-resistant corner 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 rotating shaft 118, and the control cabinet A shell 119 together constitute the control cabinet, used for the layout and installation of the internal components of the master control station and portable movement; the hard disk component 113 is used to store the system software, configuration files required for the operation of the master control station, record and save data such as collected data, operation logs, and leakage information, and at the same time provide data reading and writing services for data processing and analysis; the heat dissipation component 114 is connected to the industrial control mainboard 104 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 acquisition, processing, storage, and analysis of the entire system, and perform equipment control and status monitoring; the support frame 116 is connected to the control cabinet B shell 117 to stably place the internal components of the master control station and ensure the normal and stable operation of the components in environments such as vibration and impact; the power line carrier communication module host computer 110 is fixed on the support frame 116 by a sliding guide rail, used to modulate the digital signal sent by the master control station equipment into an analog signal transmitted by power line carrier, and at the same time demodulate the received analog signal into a digital signal to achieve data communication between the master control station and the underwater control module.

[0193] The underwater control module can refer to Figure 4 As shown in the figure, it includes a cabin structure, a dynamic pressure signal acquisition and control instruction reading unit, a dynamic pressure signal acquisition unit, and a power line carrier communication slave computer that are hermetically arranged in the cabin structure.

[0194] Specifically, the underwater control module is installed inside the basic framework 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 serves the purpose of sealing and protecting other units in the underwater control module, ensuring 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 line carrier communication slave computer is used to convert the collected data into a carrier signal and incorporate it into the transmission high-voltage.

[0195] In addition, optionally, an end cover and a sealing structure are provided for the cabin structure to achieve the sealing of the underwater control module cabin structure. It is further optional to set 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 overall underwater control box to complete position movement; the through-cabin connection module is used to lay communication cables to provide convenience for data transmission of the underwater control module). Moreover, a voltage step-down module, a centralized wiring module, and a power supply module are preferably further provided in the underwater control module. Among them, the centralized wiring module is used to transmit power and collect data; the voltage step-down module is used to provide an appropriate voltage; and the power supply module is used to provide DC power supplies with different requirements.

[0196] Moreover, as a relatively preferred embodiment of the present invention, the master control station further includes: a leakage location module. Refer to Figure 5 As shown, the leakage location 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 location result transmission unit, a leakage location result verification unit, and a leakage location result display unit.

[0197] 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 main control station power line carrier communication module 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 store data for a long time; 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 is connected to the dynamic pressure signal processing unit and is used to perform noise reduction processing on the dynamic pressure signal and detect the leakage location of the underwater pipeline; 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 effectiveness of the location 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 effective leakage location result.

[0198] The present invention provides a method and system for underwater pipeline leakage location based on dynamic pressure signals. Among them, in the underwater pipeline leakage location method, the following steps are included: Step P1: Calculate the leakage characteristics of the dynamic pressure signal under the condition of multiphase flow medium; Step P2: Correct the propagation speed of the dynamic pressure signal under the condition of multiphase flow medium; Step P3: Perform leakage location calculation on the underwater pipeline under the condition of multiphase flow medium.

[0199] The method and system for underwater pipeline leakage location based on dynamic pressure signals provided by the present invention, compared with the prior art, at least have the following technical advantages:

[0200] (1) This method and system for underwater pipeline leakage location collect the dynamic pressure signals under the condition of multiphase flow medium in the underwater pipeline. After extracting the leakage characteristics, a rapid response location calculation for underwater pipeline leakage is realized. The leakage location result is real-time and reliable, which helps to realize the real-time monitoring of underwater pipeline leakage and provides technical support for ensuring the continuity of underwater pipeline production.

[0201] (2) This method and system for underwater pipeline leakage location adopt technical means such as 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, effectively improving the accuracy of the leakage location result, and helping technicians to reveal the operating state of the underwater pipeline under different phase media and master the specific location of the leakage point.

[0202] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims described above.

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: Analyze 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 based on a statistical method; 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 gas in the tube; The process of calculating the leakage location of the underwater manifold under the multiphase flow medium condition in step P3 is 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.

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: 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.

6. The underwater manifold leakage location system based on dynamic pressure signals is characterized by: The underwater manifold leakage locating system adopts the underwater manifold leakage locating method according to any one of claims 1 to 5, 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.

7. The underwater manifold leakage locating system based on dynamic pressure signals according to claim 6 is 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.

Images