Research On Above Ground Marking And Tracking Of Oil And Gas Pipeline Internal Inspection Instrument Based On Geophone Array

Pipeline transportation has become one of the five chief transporting industries while the other four are highway carriage, railage, air-ferry and water carriage,and is playing a more and more important part in national economy and national defence. However, along with the age of pipe growth and construction blemish, the artificial reasons such as breakage and corrosion etc., pipeline leakage accident often takes place. The leakage accidents not only result in huge economy loss, but also serious environment pollution. The Pipeline Internal Detector (Smart Pig) is the most widely used equipment in detecting pipe corrosion.The above ground marker system (AGM), which is designed to locate the corrosion precisely by eliminating the cumulate error of distance the PIG passing through and avoid blindness digging, plays a pivotal role among the whole system. The tracking technology of inner inspector is used to locate the inspector in pipe from ground, when the inspector was locked in pipe.Because the shield functions of metal media of pipe, the general electromagnetic wave can hardly penetrate the pipe wall. On the other hand, the penetrable distance of traditional magnetic flux AGM was limited, and can't satisfy the new require of more deep and thicker pipeline wall.A new kind of above ground benchmarking and tracking technology of pipeline internal inspection instrument based on geophone array was proposed in this dissertation. The benchmarking was carried on by the geophone array detecting low energy voice on the pipewall. The voice was generated when the cups or discs of a pig encounter internal weld beads between the pipes and fittings ,or when the pig rubbed against the pipe wall surface. When pipeline internal inspection instrument was locked in pipeline, it was tracked by the geophone array to locate the voice which was sent by inspector.The dissertation mainly covers the following aspects:1. A above ground benchmarking technology based on geophone array according to crash voice of inspector and the weld seams of pipe was proposed. The above ground marker could benchmark deeper pipe because the crash voice could spread more distance in soil.2. A voice signal enhancement method of an independent component analyze in the wavelet domain was proposed , which in case of an unknown location information, was able to enhance the voice of internal detector in noise case environment.3. A sound signal determinant method based on the internal sound source azimuth detector was proposed. Wavelet packet entropy, empirical mode decomposition and the AR model parameters was used in the signals feature extraction method, and the artificial neural network based on support vector machine was used to identify the sound signals.4. The time difference of arrival based on signals (TDOA) location method was used. In order to improve the accuracy of delay estimation, the wavelet decomposition and the EMD method was proposed.5. An internal detector tracking method based on measurement of phase difference of fixed-frequency sound signal waveform was proposed, which was verified through experiments.6. The on-the-spot experiment was carried on to vertify the proposed theory. The hardware system architecture of above ground marker was designed, which was prepared for the practical usage.