Acoustic Emission-based Detection And Location On Leak Of Oil And Gas Gathering And Transportation Pipeline In Beach Areas

Offshore pipeline has become an important tool for offshore oil and gas gathering and transportation.If the offshore pipeline leakage,maintenance is very difficult.Finally resulting in the oil economic losses,environmental pollution and other serious consequences.Acoustic emission(AE)detection technology can achieve early detection and warning of the leak,than find the leak source quickly and easily,which is conducive to the timely repair of the leak,thus reduce leakage losses caused.The study has important significance and application value..From analysis of various factors related to the flow,sound field simulation of offshore pipeline leakage,Pipeline leakage simulation models under different conditions are established with fluent and Virtual.lab Acoustic software.Diverse factors such as leakage aperture,pressure,temperature,external environmentare are simulated.Based on the above analysis,effect of leakage flow and acoustic field distribution are analysised,which used to guide the experiment design and analysis of the acoustic emission change rules.Based on engineering experiment system,the influence of pressure,leakage aperture and pipeline surrounding medium(air soil and water)on pipeline leak AE signal was been studied.At first,pipeline leak AE signal characteristics,the signal amplitude,frequency as the variation rule of pressure,leakage aperture and pipeline surrounding medium were been analysis.Then,the influence of pressure,leakage aperture and pipeline surrounding medium(air soil and water)on pipeline leak AE signal amplitude attenuation when the signal propagation in a long straight pipeline was been studied.Acoustic emission signals are decomposed into a series of frequency bands with ‘db4’ wavelets based on wavelet packet method.Wavelet packet energy percentage,comentropy are applied to extract signal characteristic.Two-class classifications of SVM are used to the identification of leakage modes,and the prediction accuracy is 95.67% and 94.33% respectively.The location method for pipeline leakage based on the wave theory is recommended.The lead signals and continuous signals to locate leakage based on single sensor and continuous signal location based on double sensors are analyzied.Through the source location experiments of pipeline leakage detecting by AE under different environmental,the study confirmed that with the change in distance,the positioning error fluctuated between 0-5%,the average location error controlled in about 2.5%.