A Small Leak Localization Method for Oil Pipelines Based on Information Fusion

When an oil pipeline has small leaks, the change of the sound velocity of an ultrasonic signal cannot be easily detected. Based on the method of characteristics theory, the leakage occurrence mechanism of a pipeline and the propagation mechanism of the sound velocity of the ultrasonic signal along the pipeline were studied. Additionally, the computational models of generating the sound velocity of the ultrasonic signal induced by pipeline leakage and calculating the propagation attenuation of the ultrasonic wave along the pipeline were established. A small leak localization method for pipelines based on information fusion is proposed, which is a combination of the sound velocity of the ultrasonic and flow rate signals. First, the fusion signals are extracted from the signal inflection point using a modified cross-correlation to determine the time difference of the fusion signal changes at the ends of the pipeline; then, the leak position is calculated based on the information of the pipeline length and the negative pressure wave propagation velocity. Since the change of the information fusion signal induced by a small leak is larger than the change of the sound velocity of the ultrasonic signal and the change of pressure signal, the proposed method can be used to locate a small leak in a pipeline. By analyzing the acquired data of a small leak in an experimental pipeline, the results show that the proposed method can quickly and effectively locate small leaks.