Research On Pipeline Leak Detection Based On The Signal Enhancement

The pipeline is an important transportation mode for oil and gas resources.With the rapid growth of energy consumption in modern society,the development of pipeline construction has been greatly promoted.Once a pipeline leak occurs,it will cause immeasurable serious consequences.Hence its monitoring is critical.Pipeline leak detection can be divided into three steps.The first is to obtain measurements.However,the commonly used measurements(such as pressure and acoustic wave)cannot effectively characterize the slowly increasing leaks,which will lead to missing alarms.The second is to diagnose measured signals.And the most common method is the combination of the time-frequency domain feature extraction and pattern recognition.This type of method takes the entire signal as a diagnosis object resulting that it cannot distinguish and separate the leaks and interferences in a signal.The final is to locate the leak.And the common location method is based on the delayed cross-correlation analysis,where the time difference and speed determine the accuracy of the leak location.Therefore,it is of great theoretical significance and application value to study the measurements effectively characterizing abrupt and slowly increasing leaks,leak diagnosis methods and localization methods,and provide reliable technical means for pipeline leak monitoring.According to the analysis and summary of previous research on pipeline leak detection,a new method based on the pressure signal enhancement was proposed,and mainly completed the following work:1.An enhancement method of the leak pressure signal is proposed based on the digital compensator.By analyzing the advantages and disadvantages of commonly used measurements in characterizing pipeline leaks,a digital compensator with a pressure signal as the input was established based on the acoustic signal transducer to achieve the enhancement of the leak pressure signal.And field pipeline experiments show that the proposed method can not only effectively characterize slowly increasing leaks,but also provide reliable and effective leak information for leak diagnosis and location.2.The enhancement principle of the leak pressure signal is studied,and an adaptive optimization algorithm for the parameters of the digital compensator is proposed.Through the theoretical derivation of the time-domain and frequency-domain of the digital compensator,the role of its parameters in the leak pressure signal enhancement process is analyzed,which explains why the enhanced pressure signal can effectively represent the pipeline leak.Based on this,the adaptive optimization algorithm is proposed and can realize that the enhanced pressure signal effectively characterize abrupt leaks and slowly increasing leaks in real-time and online.By the field pipeline as the experimental platform,the effectiveness of the model parameter adaptive optimization algorithm proposed in this paper is verified.3.A direct-detection method for an abnormal signal is proposed.The signal decomposition method is first established to decompose a signal into multiple sub-signals.Based on the definition of signal-to-noise ratio(SNR),the functional relationship between the sub-signal SNR and the number of abnormal sub-signals is established,which realizes the direct detection of abnormal signals.Then,based on the traceability method,the specific position and amplitude of the abnormal sub-signals of the signal can be obtained.And field pipeline experiments show that the proposed method eliminates dependence on samples,avoids the offline repeated modeling process,mines the abnormal information of a signal,realizes the accurate extraction of abnormal sub-signal,and provides the basis for accurate leak location.4.A leak location method is proposed based on time difference correction.Through the theoretical derivation of the phase-frequency response characteristics of the digital compensator and the analysis of the frequency characteristics of pressure signals,a time difference correction method based on phase analysis is established,which solves the problem of inaccurate location caused by the phase shift of enhanced pressure signals.Based on the abnormal signal direct-detection method,the delay cross-correlation analysis of homopolar abnormal sub-signals in upstream and downstream signals are carried out,and the time difference correction method based on signal matching is established,which solves the missing alarm problem caused by the interference and leak mixing in a signal and realizes accurate location of leaks.Field pipeline experiments show that the leak location method proposed in this paper effectively reduces missing and false alarms,and improves the accuracy of the leak location.The research on the pipeline leak detection based on the enhancement of leak pressure signal provides effective theoretical support and technical support for the safe,stable,and efficient operation of pipeline transportation;it provides new ideas and methods for the slowly increasing leak detection of pipelines.