Lijian Zhou

Evaluation of Geological Hazard Susceptibility Based on AHP and Fuzzy Comprehensive Evaluation in Zhongwu Pipeline

By combining the two methods of AHP (Analytic Hierarchy Process) and Fuzzy (Fuzzy Comprehensive Evaluation Method), this paper processed the evaluation of geological hazard susceptibility of Zhongwu pipeline. First of all, according to the geographic background and running situation of Zhongwu pipeline, the area which Zhongwu pipeline pass is divided into 72 regions. Secondly, the paper establishes a hierarchical structure model and judgment matrix, and calculates the weight of geological hazard probability Index by AHP. Thirdly, the paper calculates the membership degree based on fuzzy comprehensive evaluation method, and achieves geological hazard susceptibility partition of Zhongwu pipeline. The result indicates that the method is reasonable and effective. At the same time, the evaluation result has upper precision and greater fitting degree than 90 percent. Finally, combining Medium-Range or Long-term Weather Forecast and the information of pipeline to achieve Long-term geological hazard warning is discussed.

Application Progress of Tri-axial MFL Sensors Technology

This paper describes the principle of tri-axial magnetic flux leakage (MFL) sensors technology and its application progress as an in-line inspection (ILI) technology into the 21st century for spiral weld anomaly inspection. According to the failure history and risk analysis, the key threat for northeastern crude pipeline of PetroChina is spiral weld anomalies. The anomaly signal characteristic recorded by tri-axial sensors was analyzed in detail. Research and field applications show that tri-axial MFL ILI tool not only can detect various usual metal loss defects, but also can identify unusual features, such as spiral weld anomalies and girth weld anomalies, but can not classify and size the weld anomalies. PetroChina finished the classification of the spiral weld anomalies and established a quantitative relationship model between the anomaly signal and anomaly size by a series of pull test studies and field dig verification studies. Research result further expands the applications of tri-axial MFL sensors technology.

A New Method for Protecting Pipeline in Summer Monsoon

In annual summer monsoon, geo-hazard is common. Monsoon-caused casualties and economic losses throughout the year accounted for 70% ∼ 80% of the total annual losses. Also, geo-hazard is a serious threat for pipeline operators to manage. Over 12,000 kilometers of pipelines with crude oil, gas, and refined oil are operated by PetroChina Pipeline Company. The pipelines, through sixteen provinces and cities, have been operated for over forty years. Geographic Information System (GIS) technology, as an effective spatial analysis tool, provides advanced analysis for pipeline geo-hazard prediction and early warning during summer monsoon based on field data and historical precipitation records. After many years of research and application of our prediction model of pipeline geo-hazard, an important link between geo-hazard and rainfall is understood. Rainfall is the main triggering factor of geo-hazards such as landslide and debris flow leading to heavy losses, especially rainstorm and heavy rainstorm. We use GIS technology to perform spatial analysis with predicted rainfall data the next twenty-four hours and the data of pipeline geo-hazard susceptibility, and predict the severity of pipeline impacts caused by geo-hazards during the next twenty-four hours. Finally, the result is modified by existed geo-hazards data. The pipeline geo-hazard early warning is divided into five ranks which are displayed by different colors, and pipelines damaged by geo-hazards and protection measures are also proposed. During July 16 and 17 of 2009 years, we released geo-hazard early warning four rank of Lanzhou-Chengdu-Chongqing Oil Pipeline through PetroChina Pipeline Company web page and the communication software of Instant Messaging. The Lanzhou-Chengdu-Chongqing Oil Pipeline Company acted promptly with a detailed deployment and emergency plan to ensure pipeline safety.Copyright

An Automatic Segmentation Algorithm Used in Pipeline Integrity Alignment Sheet Design

Pipeline segmentation design is the first step to design alignment sheet. In this step, several rectangular boxes are used to cover pipeline and each box will become the basic unit of alignment sheet design. After studying various pipeline alignment sheet mapping technologies, the author found that traditional manual design method, which can take advantage of designers’ subjectivity, causes low work efficiency. By reviewing and studying existing works at home and abroad, the author believed that it is possible and feasible to develop an automatic segmentation algorithm based on existing curve simplification algorithms to improve to improve the efficiency of pipeline section design and alignment sheet mapping. Based on several classical curve simplification algorithms, the author proposed the automatic segmentation algorithm, which automatically adjusts the location of rectangular boxes according to the number of pipeline/circle intersection points and pipeline/ rectangular box intersection points. Finally, through comparing time and result with the traditional manual method, the author proved the algorithm’s effectiveness and feasibility.Copyright