Research On Oil-Gas Pipeline Leak Detection System Based On Infrasonic Wave

With the increasing proportion of pipeline transportation in gathering system,pipeline leakage accidents occur frequently with the results of economic loss and environment pollution sometimes even serious personal injury.Leak detection of pipelines must be implemented in case of leakage accidents.The thesis focuses on the most developed infrasonic wave leak detection in the leak detection field,the results show that it performs better in precise leak location.Firstly,a realistic model is built based on principles of infrasonic wave leak detection to stimulate flow field and sound field after pipeline leakage,and find out that infrasonic wave has the strongest signal energy and the least signal decay through the propagation process,which means its signal is closest to the original ones even after the propagation process.Thus it can be used as characteristic signal of leakage.The feasibility for infrasonic wave leak detection is verified theoretically,then researches and analyses on leak detection are done under many operational behaviors,the relationship between infrasonic wave signal and pipeline pressure?leakage bore diameter?valve open time is found to instruct the development of infrasonic wave leak detection system.Secondly,according to infrasonic wave leakage detection and positioning theory,leakage location has relevance to wave velocity and leakage signal time difference between the first and last infrasonic wave sensor.The thesis mainly analyzes many parameters that affect infrasonic wave velocity and builds model to modify location formula.Thus infrasonic wave delay estimation algorithm is solved.Then time difference between the first and last infrasonic wave sensor is determined through generality correlation analysis to improve delay estimation accuracy,and reasonable wavelet basis?threshold and wavelet transform order are chosen.Jam to signal in original signal leakage is denoised by wavelet transform.It can simultaneously analyze the signal in time domain and frequency domain,and effectively distinguish abrupt parts and noise,reduce system noise and improve the signal to noise ratio,which makes it easy to leak judgment and positioning.Finally,a set of pipeline leakage detection system is developed based on LabVIEW to do the overall design of the system.It is composed of hardware and software design aspects,which mainly focus on five major program module designs,which are the front panel of the system,data acquisition,wavelet(or a wavelet packet)de-noising,correlation analysis,leak location,leak judgment and alarm,then software testing and commissioning are conducted many times.Collected data of infrasonic wave pipeline leak from the field is used to test the system.The results prove that this system has higher accuracy and stability.