Natural Gas Pipeline Leak Detection System

The pipeline is an efficient, safe and economical method of natural gas transport. And it is the primary component element of the energy lifeline in China, so the strategic status of pipeline transport is very important. However, because of the unavoidable corrosion and natural or man-made damage, it is very common that the transport pipeline of natural gas is broken or perforated.In recent years, natural gas leakage is increasing, because some lawless people usually drill holes on the transport pipelines to get extra gas that will give them enormous benefit. Such behavior results to the huge waste of the energy and the heavy pollution of the environment. Therefore, it is very important that the natural gas pipelines should be examined to ensure its integrity and normal operation.The natural gas has high compressibility and complex physical behavior, and the gas pipelines are widespread, so the traditional detection method for oil pipelines leakage is unfit for the gas pipelines, especially for the low leakage flow through nonmetallic pipelines and the leak point positioning.First, it is summarized that the present situation and characteristics of the natural gas pipelines leakage caused by man-made damage, and the application status of pipelines leakage detection technique all over the world. Then the thesis compares the hardware based and software base detecting method which is commonly used. Based on the experiment and analysis of the, attenuation and properties in both the time domain and Fourier domain of the acoustic signal, a leakage detection method using sound wave test is proposed. By using this method a monitoring scheme includes manual leakage test and wireless data collection technique, is built. The manual leakage test request staff members to search along the pipeline using portable detection instrument which can find the leakage point. The wireless data collection technique will send the collect leakage formation and the GPS coordinate to the servers by GPRS transmit technology, to form a leakage information database of natural gas pipeline in oilfield. The portable instrument contains a PDA with GPS module and GPRS module. The design proposal, consist of the detection instrument, the PDA software of data collection and signal processing, the GPRS transmission of leakage information and GPRS coordinate, and the RTDB (Real Time Database) of surveillance center, is also put forward and realized in the research.According to the require of the practical application, a RTDB of leakage information is designed and achieved on the SQL Server 2000, which can provide the real-time information to the decision maker of the oilfield. Based on the analysis of the needs of the surface engineering database in oilfield, the structure, system data tables and organizational relations of the database is built up; the design of the dynamic page and the development of the client application are also realized. The test and realization process of the database system and the design of the main interface are all discussed in the thesis.