Self-calibration real-time accurate detection method and system of multiphase flow medium in oil and gas pipeline

Abstract

The present application belongs to the technical field of oil and gas medium detection, and provides a self-calibration real-time accurate detection method and system for multiphase flow medium in an oil and gas pipeline. The method comprises: immersing a detection transmission line and a T4R calibration piece into the same detection environment; performing fluid dielectric constant inversion to obtain a dielectric constant inversion result, which is used for component analysis; and using an optimized frequency diversity sensing method to realize accurate positioning of foreign matters in the pipeline. The system comprises a calibration and sensing unit and a signal processing and control unit. The present application calibrates the measurement data of the detection transmission line and the offset reflection calibration piece by introducing a T4R calibration method, uses the calibrated measurement data of the detection transmission line and the offset reflection calibration piece for dielectric inversion, analyzes the fluid components, and the component analysis accuracy and stability are better; the calibrated measurement data of the detection transmission line is used to improve the frequency diversity sensing method, so that the dependence on prior information is eliminated, and foreign matter positioning in a packaged scene is realized.

Description

Technical Field

[0001] This invention relates to a method and system for detecting multiphase flow media in oil and gas (petroleum and natural gas) pipelines, belonging to the field of oil and gas medium detection technology. Background Technology

[0002] In the pipeline transportation of oil and gas, real-time and accurate monitoring of the composition of multiphase flow media and the distribution of foreign matter such as bubbles and rock particles within the pipeline is crucial for ensuring transportation safety, optimizing processes, and controlling the transportation process. Microwave sensing technology, due to its non-invasive nature, fast response speed, and high measurement sensitivity, is considered an effective means to achieve these objectives.

[0003] Currently, the main method for detecting multiphase flow media in oil and gas pipelines is to invert the dielectric constant of the fluid within the pipeline and then analyze its composition. However, under complex field conditions, the detection results are easily affected by factors such as the deterioration of the detection transmission linearity under extreme environments and changes in the medium, leading to low accuracy and poor stability of the dielectric constant inversion. Furthermore, existing detection methods are relatively limited in function and cannot effectively monitor the distribution of foreign matter within the fluid in real time.

[0004] The existing T4R (Through-Four Offset Reflection) calibration method utilizes at least four sets of offset reflection calibrators and one through-pass calibrator to calibrate the transmission line. Increasing the number of offset reflection calibrators (i.e., more than four sets) improves calibration bandwidth and accuracy (in this case, the 4 in T4R becomes the same number as the number of sets). The term "set" is used because when the connection structures on both sides of the transmission line (i.e., the parts on both sides of the sensing area of ​​the transmission line used for impedance matching with the connecting cable, simply referred to as the connection structure) are different, the number of offset reflection calibrators required for the two ports is different, hence four sets. The T4R calibration method can remove the response information of the connection structure of the calibrated device, avoiding interference with the response information of the DUT (in this invention, the sensing area of ​​the transmission line, and the offset reflection area of ​​the offset reflection calibrator), thus affecting the sensing results and improving the accuracy of the sensing results. The T4R calibration method (see reference: "A Multireflect-Thru Method of Vector NetworkAnalyzer Calibration", [J]. IEEE Transactions on Microwave Theory and Techniques, 2017, 65(3):905-915. DOI:10.1109 / TMTT.2016.2627036.) is an improvement on the TRL calibration method. The difference between the TRL and T4R calibration methods lies in the design and calculation process of the calibration components, but the purpose is the same. The purpose of both calibration methods is to obtain the two-port network parameters of the connection structure on both sides of the DUT (when the device being calibrated is a single-port device, only the two-port network parameters of the single-side connection structure need to be obtained). After obtaining these parameters, the means of processing the measurement data of the device being calibrated are the same and universal. For two-port devices, the scattering parameters S of the DUT are obtained through the conversion relationship between the scattering parameters S and the transmission matrix T and the cascade operation of the matrix. dut For single-port devices, the input reflection coefficient S of the DUT is obtained by performing correction calculations using the single-port error model. 11dut At this point, only the two-port network parameters of the single-sided connection structure connected to it are used for correction.

[0005] Although the T4R calibration method mentioned above is existing technology, it has not been used for oil and gas detection.

[0006] In composition measurement, the scattering parameter S of the transmission line is usually measured. 检 To determine the dielectric constant of a fluid and thus its composition, the commonly used method is the NRW algorithm. This method involves immersing two detection transmission lines into the medium under test and measuring its scattering parameter S. 检The dielectric constant of the medium is then calculated using the NRW formula. To improve measurement accuracy, calibration is usually required before measurement to reduce systematic errors. However, when the calibrated instrument is connected to an actual pipeline, the complex testing environment in the pipeline introduces new systematic errors that cannot be eliminated by pre-calibration, affecting measurement accuracy. Integrating the calibration device and the detection transmission line together in the testing environment is an effective solution to this problem, but this approach complicates the system structure, increases system hardware costs, and leads to an imbalance between the cost and benefit of optimizing the detection device.

[0007] In foreign object localization, frequency diversity sensing is an effective method. Frequency diversity sensing of transmission lines (in this invention, it refers to the detection transmission line) is divided into two schemes: with probe and without probe. The probe-based scheme obtains prior information by scanning the field distribution of the unloaded transmission line with a probe to construct a measurement matrix H; the probeless scheme measures the input reflection coefficient S of the sample object at different known positions on the transmission line. 11物 To construct the measurement matrix H using prior information, probeless frequency diversity sensing can be considered for pipeline inspection. Existing probeless frequency diversity sensing methods for transmission lines (hereinafter referred to as frequency diversity sensing) rely on prior data of the sample object at different locations on the transmission line to construct the measurement matrix H before use in the subsequent sensing process. However, obtaining the measured prior data is itself very cumbersome, and accurate measured prior information is difficult to obtain in encapsulated testing scenarios such as oil and gas measurement. Therefore, when using frequency diversity sensing for foreign object measurement in pipelines, a method for constructing the measurement matrix H that does not require measured prior data needs to be found.

[0008] Therefore, in the field of fluid detection in oil and gas pipelines, there is an urgent need for a high-precision, high-stability, and versatile multimodal detection method for oil and gas pipelines. Summary of the Invention

[0009] To address the issues of low accuracy and poor stability in existing pipeline fluid detection technologies, this invention provides a self-calibrated real-time accurate detection method for multiphase flow media in oil and gas pipelines. This method enables real-time detection of fluid components within the pipeline while simultaneously locating foreign objects such as rock particles and air bubbles. It solves the problems of low accuracy and poor stability in current pipeline component detection while achieving foreign object location. Furthermore, this invention provides a detection system for implementing the above method.

[0010] To achieve the above objectives, the present invention adopts the following technical solution.

[0011] On the one hand, the present invention provides a self-calibrated real-time accurate detection method for multiphase flow media in oil and gas pipelines, comprising the following processes:

[0012] First, the test transmission line and the T4R calibration piece (the calibration piece required for the T4R calibration method) are immersed in the same test environment, and the test transmission line and the offset reflection calibration piece are calibrated online during the test process using the T4R calibration method.

[0013] The connection structures on both sides of the detection transmission line are identical, and the offset reflection calibration components required on both sides are interchangeable. At least four offset reflection calibration components and one symmetrical through calibration component are designed for the connection structure on one side. The input reflection coefficient S of each offset reflection calibration component is measured. 11偏n Scattering parameters S of a through-type calibrator 直 The two-port network parameters of the connection structure on both sides of the detection transmission line are obtained, and these parameters are used to process the measurement data of the detection transmission line and the offset reflection calibrator; where S 11偏n In this context, 'n' represents the number of input reflection coefficients measured for the offset reflection calibrators, determined by the number of offset reflection calibrators. For measurement data from the transmission line, a two-port device calibration method is used; for measurement data from the offset reflection calibrators, a single-port device calibration method is used.

[0014] Then, the dielectric constant of the fluid is inverted for component analysis;

[0015] The fluid dielectric constant inversion involves, on the one hand, using the T4R calibration method to process the scattering parameter S of the detection transmission line. 检 Using the scattering parameter S after transmission line calibration 检校 The dielectric constant inversion is performed using the NRW algorithm; on the other hand, the input reflection coefficient S of the offset reflection calibrator is processed using the T4R calibration method. 11偏n The input reflection coefficient S after calibration using the offset reflection calibrator 11偏校n A single-port multi-line reflection method is used to perform a secondary inversion of the dielectric constant. The dielectric inversion results from the transmission line measurement data and the offset reflection calibration device measurement data are averaged after removing outliers to obtain the final dielectric constant inversion result, which is then used for component analysis. This improves measurement accuracy and stability while enhancing the application value of the calibration kit and the system's cost-effectiveness.

[0016] The single-port multi-line reflection method utilizes the single-port reflection method to calibrate the input reflection coefficient S after multiple offset reflection calibration components. 11偏校n The process involves using the measurement data from each offset reflection calibrator, combined with the offset length of each calibrator, to perform dielectric constant inversion. The single-port reflection method is an existing technology.

[0017] Outliers refer to dielectric constant inversion results that deviate significantly from other measured values ​​during the detection process, caused by the influence of large foreign objects or other environmental factors.

[0018] Finally, by utilizing an optimized frequency diversity sensing method, the problem of existing frequency diversity sensing methods relying on prior data of sample objects at different positions on the detection transmission line is overcome (which is difficult to obtain in the encapsulated testing environment of pipeline inspection), thus achieving accurate positioning of foreign objects (rocks, bubbles, etc.) in the pipeline.

[0019] The optimized frequency diversity sensing method is as follows: directly using the unloaded forward transmission coefficient S after calibration of the detection transmission line. 21空校 (Unloaded refers to the state when the detection transmission line is in the working environment but no foreign objects pass through; this data can be obtained through a data filtering algorithm.) Calculate the propagation constant γ of the sensing area when the detection transmission line is in the working environment (fluid inside the pipe), and construct the measurement matrix H using the calculated propagation constant γ. When a foreign object (bubble, rock particle, etc.) passes through the sensing area, the input reflection coefficient S of the detection transmission line... 11检 It will change, and the input reflection coefficient S after the transmission line calibration will be detected. 11检校 This can be used in the compressed sensing process to obtain the location of the foreign object.

[0020] The optimized frequency diversity sensing method described above eliminates the need for prior data on the sample object at different positions on the detection transmission line when constructing the measurement matrix H, successfully avoiding the use of prior data (because prior data is difficult to obtain during packaging testing). Therefore, the optimized frequency diversity sensing method can also be called "a frequency diversity sensing method that does not require prior data on the sample object at different positions on the detection transmission line when constructing the measurement matrix H".

[0021] The formula for calculating the propagation constant γ is:

[0022] ;

[0023] Wherein: S 21空校 To detect the unloaded forward transmission coefficient after the transmission line is calibrated, l is the length of the sensing area of ​​the transmission line.

[0024] The formula for constructing the measurement matrix H is:

[0025] ;

[0026] Where: ω is the angular frequency, i is the index of the spatial sampling point, γ[ω] represents the propagation constant γ as a function of ω, and x i These are the spatial coordinates.

[0027] The formula for the compressed sensing process is:

[0028] ;

[0029] Wherein: S 11检校To detect the input reflection coefficient after transmission line calibration, H is the measurement matrix, μ is the regularization parameter, and ρ is the estimated local reflection coefficient, which is obtained by minimizing the objective function. The location of the foreign object can be determined based on the value of ρ.

[0030] This invention introduces the T4R calibration method, which calibrates not only the measurement data of the detection transmission line but also the measurement data of the offset reflection calibrator. During component detection, the dielectric constant is inverted using the calibrated measurement data from both the detection transmission line and the offset reflection calibrator. Outliers are removed from the inversion results, and the average is taken to obtain the final dielectric constant inversion result, which is then used to analyze the fluid composition. This method improves the accuracy and stability of the inversion results while also enhancing the application value of the calibrator. For foreign object localization, the frequency diversity sensing method is optimized, utilizing the no-load forward transmission coefficient S after calibration of the detection transmission line. 21空校 (This data contains the actual propagation characteristics of the transmission line being tested), directly constructing the measurement matrix H, avoiding the use of measured prior data.

[0031] On the other hand, the present invention proposes a detection system for implementing the above method, the detection system comprising a calibration and sensing unit and a signal processing and control unit:

[0032] The calibration and sensing unit includes two detection transmission lines and a T4R calibration component. During measurement, the T4R calibration component and the detection transmission lines are placed in the same position on the oil and gas pipeline to measure the required calibration data and sensing data.

[0033] The signal processing and control unit includes a display screen, control buttons, and a processor. The processor processes calibration and sensing data using the T4R calibration method, NRW inversion algorithm, single-port multi-line reflection algorithm, and frequency diversity sensing algorithm to obtain fluid composition analysis results and foreign object location results, which are then displayed on the screen. The measurement status can be changed via the control buttons.

[0034] The T4R calibration piece and the test transmission line are fixed to the oil and gas pipeline via a connecting flange.

[0035] The measurement status includes:

[0036] (1) Calibration settings: ① Calibrate before testing; ② Calibrate at the set time intervals during testing;

[0037] (2) Component detection: ① Automatically select which inversion result to accept; ② Manually select which inversion result to accept;

[0038] (3) Foreign object location: ① Particle location; ② Bubble location; ③ Particle + bubble location.

[0039] The working process of the above system is as follows:

[0040] (1) T4R calibration improves sensing accuracy:

[0041] Since the connection structures on both sides of the detection transmission line are identical, the offset reflection calibration components required on both sides are interchangeable. Therefore, it is sufficient to design at least four offset reflection calibration components and one straight-through calibration component with symmetrical structures on both sides for the connection structure on one side only. The input reflection coefficient S of each offset reflection calibration component is measured. 11偏n Scattering parameters S of a through-type calibrator 直 The two-port network parameters of the connection structure on both sides of the detection transmission line are obtained, and the measurement data of the detection transmission line and the offset reflection calibrator are processed to remove the response information of the connection structure between the two.

[0042] (2) Fluid component detection is achieved by dielectric constant inversion:

[0043] The dielectric constant inversion consists of two parts: one is to use the scattering parameter S after transmission line calibration. 检校 The first step involves using the NRW algorithm for inversion to obtain estimated dielectric constants ε1 and ε2 based on measurement data from two detection transmission lines. The second step utilizes the input reflection coefficient S after calibration with an offset reflection calibrator. 11偏校n The single-port multi-line reflection method was used for inversion to obtain the dielectric constant estimates ε3~ε based on the measurement data of the offset reflection calibrator. m The value of m depends on the number of offset reflection calibrators used for calculation. The estimates obtained from the two different methods are averaged after removing suspected outliers to obtain the final dielectric constant inversion result.

[0044] (3) Frequency diversity sensing for foreign object localization:

[0045] After T4R calibration, the measurement reference plane during testing is located on both sides of the sensing area of ​​the detection transmission line. The no-load forward transmission coefficient S, calibrated using the detection transmission line, is then used. 21空校 (This data contains the actual propagation characteristics of the detection transmission line.) The propagation constant γ of the test process is calculated and used to construct the measurement matrix H, avoiding the problem in existing methods where the construction of the measurement matrix H depends on prior data of the sample object at different positions on the detection transmission line. When foreign objects such as bubbles and rocks pass through the sensing area, the input reflection coefficient S of the detection transmission line... 11检 It will change, and the input reflection coefficient S after the transmission line calibration will be detected. 11检校 This can be used in the compressed sensing process to obtain the location of the foreign object.

[0046] This invention calibrates the data of the detection transmission line and offset reflection calibrator by introducing the T4R calibration method, performs dielectric inversion using the calibrated measurement data, analyzes fluid composition, improves the frequency diversity sensing method using the calibrated measurement data, and changes the construction method of the measurement matrix H to eliminate dependence on prior information, thereby achieving foreign object localization in encapsulated scenarios. Compared with existing detection technologies, the detection method of this invention has better analytical accuracy and stability, and can locate foreign objects inside pipelines, showing broad application prospects. Specific technical effects are as follows:

[0047] (1) The T4R calibration algorithm can remove the interference of the connection structure response information in the measurement results, which improves the accuracy of dielectric inversion on the one hand, and lays the foundation for the optimization of frequency diversity sensing method on the other hand.

[0048] (2) When performing dielectric constant inversion to determine fluid composition, the inversion is performed by comprehensively using the calibrated data of the detection transmission line and the offset reflection calibrator, which improves the accuracy and stability of the inversion results and enhances the cost-effectiveness of the calibrator introduced into the system.

[0049] (3) Optimize the frequency diversity sensing method, change the construction method of the measurement matrix H, get rid of the dependence on prior information, and make the optimized method applicable to packaging test scenarios such as oil and gas measurement. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the self-calibrated real-time accurate detection system for multiphase flow media in oil and gas pipelines in this invention.

[0051] Figure 2 This is a schematic diagram of the T4R calibration kit and the test transmission line being calibrated.

[0052] Figure 3 This is a flowchart of the self-calibration real-time accurate detection of multiphase flow media in oil and gas pipelines according to the present invention.

[0053] Figure 4 This is a schematic diagram of the process of self-calibration real-time accurate detection of multiphase flow media in oil and gas pipelines according to the present invention.

[0054] Figure 5 This is a schematic diagram of the frequency diversity sensing process after calibration and optimization. Detailed Implementation

[0055] The self-calibrated real-time accurate detection system for multiphase flow media in oil and gas pipelines in this invention, such as... Figure 1 As shown, it includes a calibration and sensing unit as well as a signal processing and control unit.

[0056] The calibration and sensing unit includes two detection transmission lines and a T4R calibrator, used to measure the required calibration and sensing data. The T4R calibrator and detection transmission lines are placed in the same location within the oil and gas pipeline, ensuring they operate under the same measurement environment and guaranteeing the validity of the calibration results. The T4R calibrator and detection transmission lines are fixed to the oil and gas pipeline via connecting flanges.

[0057] Since the connection structures on both sides of the detection transmission line are identical, the offset reflection calibration components required on both sides are interchangeable. Therefore, it is sufficient to design four offset reflection calibration components and one straight-through calibration component with symmetrical structures on both sides for the connection structure on only one side. Figure 2 As shown. The input reflection coefficient S of the four offset reflection calibrators was measured. 11偏n (The input reflection coefficients corresponding to the four offset reflection calibration elements are S) 11偏1 S 11偏2 S 11偏3 S 11偏4 ) and a scattering parameter S of a through-type calibrator 直 This method can obtain the two-port network parameters of the connection structure on both sides of the detection transmission line, and use them to process the measurement data of the detection transmission line and the offset reflection calibrator, removing the response information of the connection structure. During measurement, it is essential to ensure that the calibrator and the detection transmission line are in the same test environment to guarantee the accuracy of the calibration results.

[0058] The signal processing and control unit includes a display screen, control buttons, and a processor. The processor processes calibration and sensing data using the T4R calibration method, NRW inversion algorithm, single-port reflection algorithm, and frequency diversity sensing algorithm to obtain fluid composition analysis results and foreign object location results, which are then displayed on the screen. Different measurement states can be changed via the control buttons, including:

[0059] (1) Calibration settings: ① Calibrate before testing; ② Calibrate at the set time intervals during testing;

[0060] (2) Component detection: ① Automatically select which inversion result to accept; ② Manually select which inversion result to accept;

[0061] (3) Foreign object location: ① Particle location; ② Bubble location; ③ Particle + bubble location.

[0062] The above system describes the process of real-time, accurate multimodal detection of multiphase flow media in oil and gas pipelines, such as... Figure 3 As shown, the following is a detailed explanation.

[0063] 1. The test transmission line and T4R calibration components are concentrated in the test area and immersed in the same test environment during the test to achieve online calibration of the test process.

[0064] 2. Perform fluid dielectric constant inversion:

[0065] On the one hand, the T4R calibration method is used to process the measurement data of the transmission line, and the scattering parameter S after the transmission line is calibrated is used. 检校 The dielectric constant inversion was performed using the NRW algorithm.

[0066] This involves using the T4R calibration method to process the data required for dielectric constant inversion and frequency diversity sensing. Existing T4R calibration methods utilize four sets of offset reflection calibration elements and one through-feed calibration element to calibrate the transmission line (device under test). The number of offset reflection calibration elements is at least four sets, and can be increased (i.e., more than four sets) to improve calibration bandwidth and accuracy (the term "sets" is used because the required calibration elements differ between the two ports when the connection structures on both sides are different; therefore, four are required per port, hence the term "four sets"). In this invention, the connection structures of both ports are identical, so only one side of the connection structure needs to be designed; therefore, it will be referred to as four sets thereafter.

[0067] On the other hand, the dielectric constant is measured a second time using the single-port multi-line reflection method (that is, the input reflection coefficient S after calibration by multiple offset reflection calibration devices using the single-port reflection method). 11偏校n The dielectric constant is calculated by processing the dielectric inversion results of the detection transmission line and the offset reflection calibration device. Outliers (dielectric constant inversion results with excessively large numerical deviations compared to other measurements) are removed, and the average value is taken to obtain the final dielectric constant inversion result, which is used for component analysis. This improves measurement accuracy and stability while enhancing the application value and system cost-effectiveness of the calibration kit. While the single-port reflection method is existing technology, because there is more than one offset reflection calibration device, this invention uses data from several offset reflection calibration devices on top of the existing single-port reflection method to improve its accuracy and stability.

[0068] While both the NRW algorithm and the single-port reflection method are existing dielectric detection techniques, this invention utilizes the calibrated data from the offset reflection calibrator for dielectric inversion in the single-port reflection method. This improves inversion accuracy and stability. Furthermore, the measurement data from the offset reflection calibrator is used in this process, increasing its utilization rate. Introducing calibration into detection requires adding multiple measurement ports, which undoubtedly complicates the system hardware and increases system cost. Therefore, in existing applications, considering the balance between the performance improvement brought by calibration and the increased hardware cost, it is not advisable to introduce calibration into the detection process. However, using the measurement data from the offset reflection calibrator for dielectric inversion improves the utilization rate of the data obtained after the complexity, thus improving the system's cost-effectiveness.

[0069] 3. By utilizing an optimized frequency diversity sensing method, the problem of existing frequency diversity sensing methods relying on prior data of sample objects at different positions on the detection transmission line is overcome (this prior data is difficult to obtain in the encapsulated testing environment of pipeline inspection), thus achieving accurate positioning of foreign objects (rocks, bubbles, etc.) in the pipeline.

[0070] Frequency diversity sensing consists of two parts: frequency diversity and compressed sensing. In frequency diversity sensing, a measurement matrix H needs to be constructed during frequency diversity. This process requires prior data from sample objects at different positions on the detection transmission line to construct the measurement matrix H. However, the frequency diversity sensing method optimized in this invention directly uses the unloaded forward transmission coefficient S after calibration of the detection transmission line. 21空校 The propagation constant γ is calculated in the sensing region of the detection transmission line, and the calculated propagation constant γ is used to construct the measurement matrix H. This avoids the use of the aforementioned prior data, as such prior data is difficult to obtain during packaging testing. The method of this invention can be simply referred to as a frequency diversity sensing method that does not require prior data of the sample object at different positions on the detection transmission line when constructing the measurement matrix H.

[0071] The following combination Figure 4 A detailed explanation of the testing process.

[0072] (1) T4R calibration improves sensing accuracy:

[0073] By measuring the input reflectance S of four offset reflector calibrators 11偏n (S) 11偏1 S 11偏2 S 11偏3 S 11偏4 ) and a scattering parameter S of a through-type calibrator 直 This method can obtain the two-port network parameters of the connection structure on both sides of the detection transmission line, and use them to process the measurement data of the detection transmission line and the offset reflection calibrator, removing the response information of the connection structure. During measurement, it is essential to ensure that the calibrator and the detection transmission line are in the same test environment to guarantee the accuracy of the calibration results.

[0074] (2) Fluid component detection is achieved by dielectric constant inversion:

[0075] The dielectric constant inversion consists of two parts: one is to use the scattering parameter S after transmission line calibration. 检校 The first step involves using the NRW algorithm for inversion to obtain estimated dielectric constants ε1 and ε2 based on measurement data from two detection transmission lines. The second step utilizes the input reflection coefficient S after calibration with an offset reflection calibrator. 11偏校n The single-port multi-line reflection method was used for inversion to obtain the dielectric constant estimates ε3~ε based on the measurement data of the offset reflection calibrator. m(The value of m depends on the number of offset reflection calibrators used for calculation), and the estimated values ​​obtained from the two different methods are averaged after removing suspected outliers to obtain the final dielectric constant inversion result.

[0076] In this invention, to reduce the size of the calibration and sensing units, the offset length of offset reflection calibrator 1 is 0. Therefore, only the data from three offset reflection calibrators (offset reflection calibrators 2, 3, and 4) are used for dielectric constant inversion, hence m = 2 + 3 = 5. If the offset length of offset reflection calibrator 1 is not 0, its calibrated data can also be used for inversion. This scheme improves the inversion accuracy and stability while enhancing the application value of the offset reflection calibrator measurement data, thereby improving the cost-effectiveness of the system hardware complexity.

[0077] 3) Frequency diversity sensing for foreign object localization:

[0078] The core formula for frequency diversity sensing is as follows:

[0079] 1. Formula for calculating the propagation constant γ:

[0080] ;

[0081] Wherein: S 21空校 To detect the unloaded forward transmission coefficient after the transmission line is calibrated, l is the length of the sensing area of ​​the transmission line.

[0082] 2. Construction of measurement matrix H:

[0083] ;

[0084] Where: ω is the angular frequency, i is the index of the spatial sampling point, γ[ω] represents the propagation constant γ as a function of ω, and x i These are the spatial coordinates.

[0085] 3. Formula for compressed sensing process:

[0086] ;

[0087] Wherein: S 11检校 To detect the input reflection coefficient after transmission line calibration, H is the measurement matrix, μ is the regularization parameter, and ρ is the estimated local reflection coefficient, which is obtained by minimizing the objective function. The location of the foreign object can be determined based on the value of ρ.

[0088] like Figure 5 As shown, after processing using the T4R calibration method, the measurement reference plane during testing is located on both sides of the sensing area of ​​the detection transmission line. The no-load forward transmission coefficient S, calibrated using the detection transmission line, is then used. 21空校(This data contains the actual propagation characteristics of the detection transmission line.) The propagation constant γ of the test process is calculated and used to construct the measurement matrix H, avoiding the problem in existing methods where the construction of the measurement matrix H depends on prior data of the sample object at different positions on the detection transmission line. When foreign objects such as bubbles and rocks pass through the sensing area, the input reflection coefficient S of the detection transmission line... 11检 It will change, and the input reflection coefficient S after the transmission line calibration will be detected. 11检校 This can be used in the compressed sensing process to obtain the location of the foreign object.

Claims

1. A self-calibrated real-time accurate detection method for multiphase flow media in oil and gas pipelines, characterized in that, The process includes the following: First, the detection transmission line and the T4R calibration piece are immersed in the same detection environment, and the online calibration of the detection transmission line and the offset reflection calibration piece is achieved through the T4R calibration method during the detection process. Then, the dielectric constant of the fluid is inverted for component analysis; Finally, by using an optimized frequency diversity sensing method, the accurate location of foreign objects in the pipeline is achieved. The connection structures on both sides of the detection transmission line are identical, and the offset reflection calibration components required on both sides are interchangeable. At least four offset reflection calibration components and one symmetrical through calibration component are designed for the connection structure on one side. The input reflection coefficient S of each offset reflection calibration component is measured. 11偏n Scattering parameters S of a through-type calibrator 直 The two-port network parameters of the connection structure on both sides of the detection transmission line are obtained, and these parameters are used to process the measurement data of the detection transmission line and the offset reflection calibrator; where S 11偏n In this context, 'n' represents the number of input reflection coefficients measured by the offset reflection calibrator, which is determined by the number of offset reflection calibrators. The optimized frequency diversity sensing method is as follows: directly using the unloaded forward transmission coefficient S after calibration of the detection transmission line. 21空校 The propagation constant γ of the sensing area is calculated when the transmission line is in the working environment. A measurement matrix H is constructed using the calculated propagation constant γ. When a foreign object passes through the sensing area, the input reflection coefficient S of the transmission line is measured. 11检 It will change, and the input reflection coefficient S after the transmission line calibration will be detected. 11检校 Used for compressed sensing processes, i.e., to obtain the location of foreign objects; The formula for calculating the propagation constant γ is: ； Wherein: S 21空校 To detect the no-load forward transmission coefficient of the transmission line after calibration, l is the length of the sensing area of ​​the transmission line. The formula for constructing the measurement matrix H is: ； Where: ω is the angular frequency, i is the index of the spatial sampling point, γ[ω] represents the propagation constant γ as a function of ω, and x i Spatial location coordinates; The formula for the compressed sensing process is: ； Wherein: S 11检校 To detect the input reflection coefficient after transmission line calibration, H is the measurement matrix, μ is the regularization parameter, and ρ is the estimated local reflection coefficient, which is obtained by minimizing the objective function. The location of the foreign object is determined based on the value of ρ.

2. The self-calibrated real-time accurate detection method for multiphase flow media in oil and gas pipelines according to claim 1, characterized in that, The fluid dielectric constant inversion involves, on the one hand, using the T4R calibration method to process the scattering parameter S of the detection transmission line. 检 Using the scattering parameter S after transmission line calibration 检校 The dielectric constant inversion is performed using the NRW algorithm; on the other hand, the input reflection coefficient S of the offset reflection calibrator is processed using the T4R calibration method. 11偏n The input reflection coefficient S after calibration using the offset reflection calibrator 11偏校n The dielectric constant was inverted twice using the single-port multi-line reflection method. The dielectric inversion results of the transmission line measurement data and the dielectric inversion results of the offset reflection calibration device were averaged after removing outliers to obtain the final dielectric constant inversion result, which was then used for component analysis.

3. The self-calibrated real-time accurate detection method for multiphase flow media in oil and gas pipelines according to claim 2, characterized in that, The single-port multi-line reflection method utilizes the single-port reflection method to calibrate the input reflection coefficient S after multiple offset reflection calibration components. 11偏校n The data is processed, and the dielectric constant is inverted by combining the measurement data of each offset reflection calibrator with the offset length of each offset reflection calibrator.

4. The self-calibrated real-time accurate detection method for multiphase flow media in oil and gas pipelines according to claim 2, characterized in that, The outlier refers to the dielectric constant inversion result that shows an abnormally large deviation from other measured values ​​during the detection process.

5. A self-calibrating real-time accurate detection system for multiphase flow media in oil and gas pipelines, used to implement the self-calibrating real-time accurate detection method for multiphase flow media in oil and gas pipelines as described in any one of claims 1-4, characterized in that, Includes calibration and sensing units as well as signal processing and control units: The calibration and sensing unit includes two detection transmission lines and a T4R calibration component. During measurement, the T4R calibration component and the detection transmission lines are placed in the same position on the oil and gas pipeline to measure the required calibration data and sensing data. The signal processing and control unit includes a display screen, control buttons, and a processor. The processor processes calibration data and sensing data using the T4R calibration method, NRW inversion algorithm, single-port multi-line reflection algorithm, and frequency diversity sensing algorithm to obtain fluid composition analysis results and foreign object location results, which are then displayed on the screen. The measurement status can be changed via the control buttons.

6. The self-calibrating real-time accurate detection system for multiphase flow media in oil and gas pipelines according to claim 5, characterized in that, The T4R calibration piece and the test transmission line are fixed to the oil and gas pipeline via a connecting flange.

7. The self-calibrating real-time accurate detection system for multiphase flow media in oil and gas pipelines according to claim 5, characterized in that, The measurement status includes: (1) Calibration settings: ① Calibrate before testing; ② Calibrate at the set time intervals during testing; (2) Component detection: ① Automatically select which inversion result to accept; ② Manually select which inversion result to accept; (3) Foreign object location: ① Particle location; ② Bubble location; ③ Particle + bubble location.

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