Multiphase flow pipeline leakage signal monitoring system and positioning method

Abstract

The invention discloses a multiphase flow pipeline leakage signal monitoring system and a positioning method, and the system comprises infrasound sensors disposed at two ends of a multiphase flow pipeline, the infrasound sensors are in signal connection with an infrasound data collector, the infrasound data collector is in signal connection with a signal processing module, and the signal processing module is connected with a monitoring center through a base station. Collected signals are processed by the signal processing module and then transmitted to a monitoring center for leakage position identification and early warning. The positioning method specifically comprises the following steps: acquiring a leakage signal of the multiphase flow pipeline through the infrasound sensor, and transmitting the leakage signal to the infrasound data collector; the infrasound data collector converts the leakage signal into a digital signal and transmits the digital signal to the signal processing module; the signal processing module processes the digital signal and then uploads the digital signal to a monitoring center; and the monitoring center determines the leakage point position of the multiphase flow pipeline based on the processed digital signal and performs early warning. The leakage of the multiphase flow pipe can be monitored in time, and the leakage point can be accurately positioned.

Description

Technical Field

[0001] The present invention belongs to the technical field of pipeline leakage monitoring, and particularly relates to a multiphase flow pipeline leakage signal monitoring system. The present invention also relates to a method for locating the above-mentioned multiphase flow pipeline leakage signal. Background Art

[0002] As an important channel for transporting oil and gas resources, pipelines are known as the "lifeline" of the oil and gas industry. The problem of oil and gas pipeline leakage has received unprecedented attention and emphasis, which is not only an economic issue, but more importantly, a safety and environmental issue. At present, multiphase flow pipelines are used for transporting oil and gas resources. Due to the extremely complex internal medium fluid and flow pattern of multiphase flow pipelines and large pipeline noise interference, there are problems such as low sensitivity, low positioning accuracy, high false alarm rate / miss rate, and inaccurate leakage monitoring and positioning when using existing technologies to monitor their leakage. For example, common methods for monitoring oil and gas pipeline leakage in the prior art include: negative pressure wave method, distributed optical fiber method, flow balance method, and acoustic wave method.

[0003] The negative pressure wave method requires a sudden pressure drop and is applicable to liquid pipelines with large leaks, resulting in low monitoring accuracy.

[0004] When the distributed optical fiber method is used for monitoring oil and gas pipeline leakage, a sensing optical fiber needs to be laid in the same trench along the pipeline above the monitored pipeline, and optical pulse waves with a certain time and power are continuously emitted into the optical fiber. However, the distributed optical fiber detection technology needs to be laid parallel to the pipeline, with high cost, and is easily contaminated by leakage substances and damaged by third parties, resulting in failure.

[0005] The flow balance method is difficult to determine the location of the leakage point and cannot perform leakage point positioning.

[0006] The acoustic wave detection method is a leakage detection system developed based on the principle that collisions between objects will generate vibrations, emit sounds, and form acoustic waves. Since the internal of multiphase flow pipelines is mainly three-phase flow of oil, water, and gas, the flow pattern is related to gas phase velocity, liquid phase (oil-water mixture) velocity, gas-liquid phase density difference, pipeline inclination, etc., and the flow pattern and flow state are extremely complex. The medium for acoustic wave propagation is a mixed medium, which forms a strong scattering and absorption phenomenon for acoustic wave propagation, increasing the attenuation of acoustic wave propagation. In addition, different stratifications of gas-oil-water stratified flow will cause the phenomenon of multi-path and different velocities of acoustic wave propagation, resulting in deformation of acoustic waves during propagation, thus causing great difficulties in discriminating the correlation of leakage acoustic signals at different positions. Summary of the Invention

[0007] The purpose of the present invention is to provide a multiphase flow pipeline leakage signal monitoring system, which can timely monitor the leakage of multiphase flow pipelines and accurately locate the leakage point.

[0008] Another purpose of the present invention is to provide a method for locating a multiphase flow pipeline leakage signal.

[0009] The first technical solution adopted by the present invention is a multiphase flow pipeline leakage signal monitoring system, which includes infrasound sensors arranged at both ends of the multiphase flow pipeline. The infrasound sensors are signal-connected to an infrasound data collector, and the infrasound data collector is signal-connected to a signal processing module. The signal processing module is connected to a monitoring center through a base station, and the collected signals are processed by the signal processing module and then transmitted to the monitoring center for leakage position identification and early warning.

[0010] The feature of the first technical solution of the present invention is further that

[0011] An integrator, a differentiator, a discriminator and a filter are arranged in the signal processing module.

[0012] The infrasound data collector includes a signal conversion module for converting the leakage acoustic wave signal into a digital signal in a fixed format.

[0013] The second technical solution adopted by the present invention is a method for locating the leakage signal of a multiphase flow pipeline, which includes the following steps:

[0014] Step 1, obtaining the leakage signal of the multiphase flow pipeline through an infrasound sensor and transmitting it to the infrasound data collector;

[0015] Step 2, the infrasound data collector converts the leakage signal into a digital signal and then transmits it to the signal processing module;

[0016] Step 3, the signal processing module processes the digital signal and uploads it to the monitoring center;

[0017] Step 4, the monitoring center determines the leakage point position of the multiphase flow pipeline based on the processed digital signal and issues an early warning.

[0018] The feature of the second technical solution of the present invention is further that

[0019] The processing of the digital signal in Step 3 specifically includes denoising, feature extraction, feature recognition and screening of the leakage signal in sequence.

[0020] The denoising specifically includes smoothing and filtering the leakage signal through an integrator to achieve the purpose of denoising. The specific formula is as follows:

[0021]

[0022] Among them, x(n) is the input signal; h s (k - n) is the unit impulse response during denoising; * represents convolution;

[0023] The feature extraction specifically includes distinguishing whether the waveform of the collected leakage signal is a falling edge or a rising edge through a differentiator and extracting its features. The specific formula is as follows:

[0024]

[0025] Among them, s(n) is the input signal of the current stage; h d (k - n) is the unit impulse response during feature extraction, and * represents convolution;

[0026] Feature recognition specifically involves finding the falling edge time section of the leakage signal after feature extraction through a discriminator. The specific formula is as follows:

[0027]

[0028] When d(k) ≤ 0, s(k) is the falling edge; when d(k) > 0, s(k) is 0;

[0029] Screening specifically involves screening out the falling edges of the leakage signal through a filter, calculating the algebraic sum of the signal waveform values in all falling edge time sections, then sorting them in ascending order according to the magnitude of the numerical sum, and selecting the first M items with the smallest algebraic sum value. The specific formula is as follows:

[0030]

[0031] Among them, i is; M is the number of waveform value items selected;

[0032] In the falling edge time section, the larger the absolute value of the negative value of the numerical sum, the more certain it is determined to be a leakage signal.

[0033] Determining the leakage point position of the multiphase flow pipeline in step 4 is specifically as shown in the following formula:

[0034]

[0035] Among them, x is the leakage point position, L is the distance between the head and end sections of the pipeline, v is the propagation speed of sound waves in the pipeline medium, u is the flow rate of the medium in the pipeline, t 1 is the time for the sound wave to reach the head sensor, t 2 is the time for the sound wave to reach the end sensor.

[0036] The beneficial effect of the present invention is that the multiphase flow pipeline leakage signal monitoring system and positioning method of the present invention set infrasound sensors at both ends of the multiphase flow pipeline to receive the sound wave signals generated by the friction between the multiphase flow pipeline and the pipe wall after leakage under the action of the internal medium pressure; by processing the sound wave signals and based on the time difference of the signal mutation received by the two infrasound sensors at both ends and the speed of sound wave transmission in the pipeline medium, accurately infer the leakage position of the multiphase flow pipeline, and timely send an alarm to notify the staff for processing, reducing the losses and hazards caused by pipeline leakage. Description of the Drawings

[0037] Figure 1 It is a schematic diagram of the hardware structure of the multi-phase flow pipeline leakage signal monitoring system of the present invention;

[0038] Figure 2 It is a schematic flow diagram of the method for locating the leakage signal of the multi-phase flow pipeline of the present invention;

[0039] Figure 3 It is a schematic diagram of the structure of the infrasound sensor in the multi-phase flow pipeline leakage signal monitoring system of the present invention.

[0040] In the figure, 1. Multi-phase flow pipeline, 2. Infrasound sensor, 3. Infrasound data collector, 4. Base station, 5. Monitoring center, 6. Signal conversion module, 7. Integrator, 8. Differentiator, 9. Judger, 10. Sorter, 11. Signal processing module. Specific embodiments

[0041] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] As Figure 1 shown, the multi-phase flow pipeline leakage signal monitoring system disclosed by the present invention includes infrasound sensors 2 provided at both ends of the multi-phase flow pipeline 1. The infrasound sensors 2 are signal-connected to an infrasound data collector 3.

[0043] The infrasound sensors 2 only monitor the dynamic pressure of the multi-phase flow pipeline 1 and do not monitor the static pressure. After receiving the leakage signal of the multi-phase flow pipeline 1, they output a dynamic infrasound electrical signal of 4 mA to 20 mA to the infrasound data collector 3; at the same time, the infrasound sensors 2 can withstand a high pressure of 20 Mpa in the pipeline and airtightness.

[0044] The infrasound data collector 3 is connected to a signal processing module 11. The signal processing module 11 is connected to a monitoring center 5 through a base station 4. As Figure 3 shown, an integrator 7, a differentiator 8, a judger 9 and a sorter 10 are provided in the signal processing module 11 for processing the digital signal converted by the infrasound data collector 3.

[0045] The main communication means include optical cable network communication, 4G wireless mobile network communication or wireless bridge communication. The infrasound data collector 3 is a real-time high-speed and high-precision dedicated processor for data processing, and a high-performance industrial control-level processor is used for high-speed and high-precision data acquisition and network data communication. The Beidou / GPS timekeeping system is adopted, a reliable wide-range voltage input and a reliable hardware watchdog are designed, and it has functions of fully automatic high-precision data sampling, analog-to-digital conversion, satellite timekeeping, data network communication and shielding pump station noise.

[0046] The infrasound data collector 3 includes a signal conversion module 6 for converting the leakage acoustic wave signal into a digital signal in a fixed format. The signal conversion module 6 mainly performs A / D conversion. A / D conversion is the conversion from analog quantity to digital quantity, relying on an analog-to-digital converter.

[0047] The signal processing module 11 transmits the processed digital signal to the monitoring center 5 for leakage location identification and early warning. The monitoring center 5 runs based on a workstation or a server, mainly for receiving the digital signal transmitted through the signal processing module 11, and judging the leakage location and giving early warning according to the received data.

[0048] Embodiment 1

[0049] As Figure 2 shown, the multi-phase flow pipeline leakage signal positioning method disclosed by the present invention includes the following steps:

[0050] Step 1, obtaining the leakage signal of the multi-phase flow pipeline 1 through the infrasound sensor 2 and transmitting it to the infrasound data collector 3;

[0051] Step 2, the infrasound data collector 3 converts the leakage signal into a digital signal and then transmits it to the signal processing module 11;

[0052] Step 3, the signal processing module 11 processes the digital signal and uploads it to the monitoring center 5;

[0053] Step 4, the monitoring center 5 determines the leakage point position of the multi-phase flow pipeline 1 based on the processed digital signal and gives an early warning.

[0054] After the multi-phase flow pipeline 1 leaks, under the action of the pressure of the medium in the pipeline, acoustic wave signals will be generated by friction with the pipe wall. The acoustic wave signals will propagate upstream and downstream along the multi-phase flow pipeline 1. During the propagation process, the high-frequency part will gradually attenuate with the increase of the transmission distance, and the low-frequency part attenuates more slowly and will be received by the infrasound sensors 2 installed at both ends of the multi-phase flow pipeline 1. By judging the time difference of the signal mutation received, the leakage position is located.

[0055] Embodiment 2

[0056] Step 1, obtaining the leakage signal of the multi-phase flow pipeline 1 through the infrasound sensor 2 and transmitting it to the infrasound data collector 3;

[0057] Step 2, the infrasound data collector 3 converts the leakage signal into a digital signal and then transmits it to the signal processing module 11;

[0058] Step 3, the signal processing module 11 processes the digital signal and uploads it to the monitoring center 5;

[0059] Step 4, the monitoring center 5 determines the leakage point location of the multiphase flow pipeline 1 based on the processed digital signal and issues an early warning, as shown in the following formula:

[0060]

[0061] where x is the leakage point location, L is the distance between the head and end sections of the pipeline, v is the propagation speed of sound waves in the pipeline medium, u is the flow velocity of the medium in the pipeline, t 1 is the time for the sound wave to reach the head sensor, and t 2 is the time for the sound wave to reach the end sensor.

[0062] Embodiment 3

[0063] Step 1, the leakage signal of the multiphase flow pipeline 1 is acquired by the infrasound sensor 2 and transmitted to the infrasound data collector 3;

[0064] Step 2, the infrasound data collector 3 converts the leakage signal into a digital signal and then transmits it to the signal processing module 11;

[0065] Step 3, the signal processing module 11 processes the digital signal and uploads it to the monitoring center 5;

[0066] Since the leakage signal propagates to the sensor presenting a multi-peak oscillation signal characteristic, directly performing a correlation operation on the monitoring signals of the head and end sensors, the correlation peak may appear at any peak point of the oscillation signal. To overcome the problem of multiple correlation peaks with similar magnitudes caused by directly correlating the signals collected by the head and end sensors of the pipeline, the leakage signal is successively denoised, feature-extracted, feature-identified, and screened through the integrator 7, differentiator 8, discriminator 9, and filter 10.

[0067] The signal collected by the downstream booster station is severely amplitude-limited and distorted, which is not beneficial to signal processing. The denoising is specifically to perform smoothing filtering on the leakage signal to overcome the amplitude-limited distortion of the sensor-collected monitoring signal caused by the pipeline operating conditions, achieving the purpose of denoising. The specific formula is as follows:

[0068]

[0069] where x(n) is the input signal; h s (k - n) is the unit impulse response during denoising; * represents convolution;

[0070] Feature extraction specifically distinguishes whether the waveform of the collected leakage signal is a falling edge or a rising edge and extracts its features. Mathematically, the rising edge of the waveform becomes positive after differentiation, while the falling edge we are concerned about becomes negative after differentiation. The specific formula is as follows:

[0071]

[0072] Among them, s(n) is the input signal of the current stage; h d (k - n) is the unit impulse response during feature extraction, and * represents convolution;

[0073] Feature recognition specifically involves using the discriminator 9 to find the falling edge time section of the leakage signal after feature extraction. The specific formula is as follows:

[0074]

[0075] When d(k) ≤ 0, s(k) is the falling edge; when d(k) > 0, s(k) is 0;

[0076] The screening specifically involves using the filter (10) to screen out the falling edges of the leakage signal, calculating the algebraic sum of the signal waveform values in all falling edge time sections, then sorting them in ascending order according to the magnitude of the numerical sum, and selecting the first M items with the smallest algebraic sum value. The specific formula is as follows:

[0077]

[0078] Among them, i is; M is the number of falling edge time sections;

[0079] In the falling edge time section, the larger the absolute value of the negative value of the numerical sum, the more certain it is determined to be a leakage signal.

[0080] Step 4, the monitoring center 5 determines the leakage point location of the multiphase flow pipeline 1 based on the processed digital signal and issues an early warning; specifically as shown in the following formula:

[0081]

[0082] Among them, x is the leakage point location, L is the distance between the head and end of the pipeline, v is the propagation speed of sound waves in the pipeline medium, u is the flow rate of the medium in the pipeline, t 1 is the time when the sound wave reaches the head sensor, t 2 is the time when the sound wave reaches the end sensor.

Claims

1. A monitoring system for leakage signals of multiphase flow pipelines, characterized in that, it includes infrasound sensors (2) arranged at both ends of the multiphase flow pipeline (1). The infrasound sensors (2) are signal-connected to an infrasound data collector (3). The infrasound data collector (3) is signal-connected to a signal processing module (11). The signal processing module (11) is connected to a monitoring center (5) through a base station (4). The collected signals are processed by the signal processing module (11) and then transmitted to the monitoring center (5) for leakage position identification and early warning.

2. The monitoring system for leakage signals of multiphase flow pipelines according to claim 1, characterized in that, an integrator (7), a differentiator (8), a decision maker (9) and a filter (10) are arranged in the signal processing module (11).

3. The monitoring system for leakage signals of multiphase flow pipelines according to claim 2, characterized in that, the infrasound data collector (3) includes a signal conversion module (6) for converting the leakage acoustic wave signal into a digital signal in a fixed format.

4. A method for locating leakage signals of multiphase flow pipelines, characterized in that, using the monitoring system for leakage signals of multiphase flow pipelines according to any one of claims 1 to 3, including the following steps: Step 1, obtain the leakage signal of the multiphase flow pipeline (1) through the infrasound sensor (2) and transmit it to the infrasound data collector (3); Step 2, the infrasound data collector (3) converts the leakage signal into a digital signal and then transmits it to the signal processing module (11); Step 3, the signal processing module (11) processes the digital signal and uploads it to the monitoring center (5); Step 4, the monitoring center (5) determines the leakage point position of the multiphase flow pipeline (1) based on the processed digital signal and issues an early warning.

5. The method for locating leakage signals of multiphase flow pipelines according to claim 4, characterized in that, the processing of the digital signal in Step 3 specifically includes denoising, feature extraction, feature recognition and screening of the leakage signal in sequence.

6. The method for locating leakage signals of multiphase flow pipelines according to claim 5, characterized in that, the denoising is specifically to perform smoothing filtering on the leakage signal through the integrator (7) to achieve the purpose of denoising. The specific formula is as follows: where x(n) is the input signal; h s (k - n) is the unit impulse response during denoising; * represents convolution; the feature extraction is specifically to distinguish whether the waveform of the collected leakage signal is a falling edge or a rising edge through the differentiator (8) and perform feature extraction on it. The specific formula is as follows: where s(n) is the input signal of the current stage; h d (k - n) is the unit impulse response during feature extraction, and * represents convolution; the feature recognition is specifically to find the falling edge time section of the leakage signal after feature extraction through the decision maker (9). The specific formula is as follows: When d(k) ≤ 0, s(k) is the falling edge. When d(k) > 0, s(k) is 0; the screening is specifically to screen out the falling edges where the leakage signal occurs through the filter (10), calculate the algebraic sum of the signal waveform values in all falling edge time sections, and then sort them in ascending order according to the magnitude of the numerical sum, and select the first M items with the smallest algebraic sum value. The specific formula is as follows: where i is; M is the number of waveform numerical items selected; In the falling edge time section, the larger the absolute value of the negative value of the numerical sum, the more it is determined to be a leakage signal.

7. The method for locating a leakage signal in a multiphase flow pipeline according to claim 4, characterized in that the specific method for determining the leakage point position of the multiphase flow pipeline (1) in step 4 is as shown in the following formula: where x is the location of the leakage point, L is the distance between the start and end sections of the pipeline, v is the propagation speed of sound waves in the pipeline medium, u is the flow velocity of the medium in the pipeline, t 1 is the time for the sound wave to reach the first-end sensor, and t 2 is the time for the sound wave to reach the last-end sensor.

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