Корреляционно-экстремальный метод оценивания координат мест утечек нефти в магистральных нефтепроводах

Abstract

Background Oil leaks from pipelines, including unauthorized cut-ins, cause substantial economic and ecological damage during operation of the Russian oil pipelines. Published materials demonstrate continual growth of the damage. Numerous methods have been developed to determine coordinates of leaks and cut-ins. The methods are based on using various physical laws and phenomena and differ in their sensitivity to noise, noise immunity, dependence on the natural factors, speed and accuracy of determining coordinates of leaks and cut-ins. Yet, neither of these methods solves the problem of locating the pipeline damage in real time. The methods also differ in the frequency range of received and processed sound vibrations – low-frequency infrasonic and high-frequency. Infrasonic detection systems seem to be most promising, where the signal detection and propagation distance are considered. Aims and Objectives Math modeling of a dampening infrasonic signal and evaluating the accuracy of detecting coordinates of leakages, caused by authorized/unauthorized cut-in or corrosion of the main oil pipeline, where the signal is disturbed by noises of different intensity and the parameters of the signal math model are unknown. Methods Speed and accuracy of locating the source of the signal may be determined by two methods: a) evaluation of the moment of the first entrance of and signals into П 1 and П 2 receivers by calculating spectral density of energy and/or dispersion of the signal in the given «sliding window»; b) evaluation (making precise) of the time lag of one signal in relation to the other signal by finding the maximum mutual correlation function of spectral density of the compared signal energy, which allow to exclude the influence of signal damping on the accuracy of evaluating . Results Accuracy of evaluating the time lag of one signal in relation to the other signal is studied on the base of the developed math model of damping infrasonic vibrations generated by a source and received by two receivers with some delay. It is demonstrated that the accuracy depends both on the relative position of the signal source and the receivers, and on the signal/noise relation. Signal model and methods of signal processing allow to select monitoring system parameters (coordinates of receivers), that ensure the highest accuracy of evaluating the time lag . Conclusion It is studied whether math models of damping infrasonic vibrations generated by certain resources can be used for designing oil pipeline monitoring systems, which determine the coordinates of the signal generating source.