A Field-Pipeline Leakage Detection Method Based on Negative Pressure Wave and Improved Fast Differential Algorithm

Author(s):  
Han Li ◽  
De-Yun Xiao ◽  
Xiang Zhao
Author(s):  
Yibo Li ◽  
Liying Sun ◽  
Shijiu Jin ◽  
Likun Wang ◽  
Dongjie Tan

Negative pressure wave (NPWs) technique is an effective method for oil leakage detection and location. However, conventional negative pressure wave technology failed to be applied to leakage location in China directly. China’s crude oil has to be transmitted over heating because of its high viscosity, high wax and high solidifying point. In this paper, conventional location method of instantaneous pressure wave was analyzed and techniques were developed to overcome the defects. Since temperature of the oil would drop continuously during transmission, temperature drop influence on physical characteristics of the crude oil and propagation velocity of pressure wave was studied in detail. In order to achieve high precision, wavelet transform algorithm was adopted to define inflexion of negative pressure wave when it propagates along the pipe, and wavelet threshold denoising technique was used to separate the characteristic inflexion of negative pressure wave when calculating the leak position. The problem of false alarms was solved by application of eigenvector indexes method. On the basis of that, a new oil leakage detection and location system was developed for hot oil transmission pipeline. In China, SCADA (supervisory control and data acquisition) system was installed on most oil transmission pipeline to monitor operational parameters for long range crude oil or product oil pipeline. Because it acquires pipeline operational parameters from the existing SCADA system, the cost and complexity of the new system was greatly reduced. The earliest leak detection and location system which installed on a hot oil transmission pipeline in PetroChina 5 years ago is still working well. It responds to leakage (1.5% of the total fluid) within 2 minutes and location error is less than 2% of the pipeline length between the two stations.


Author(s):  
Dongliang Yu ◽  
Laibin Zhang ◽  
Liang Wei ◽  
Zhaohui Wang

The appearance of a rupture, leak or damage in the long-distance oil & gas pipeline, which could cause a leak, usually generates a non-linear & chaotic negative pressure wave signal. By properly interpreting the negative pressure wave signature, it is possible to detect a leak along the pipeline. Most traditional noise reduction methods are established based on the linear system, which are not in line with the actual non-linear & chaotic situation. Therefore, the weak negative pressure wave signals, generated by small leaks, are often filtered out and cause false alarm and failure alarm. In order to resolve the problem, this paper uses the non-linear projective algorithm for noise reduction. First, the weak negative pressure wave signal series would be reconstructed using delay coordinates, in the high dimensional phase space, the background signal, the negative pressure wave signal and the noise signal are separated into different sub-spaces. Through the reconstruction of sub-spaces, the weak pressure wave signal can be isolated from the background signal as well as the random noise component reduced.


2013 ◽  
Vol 313-314 ◽  
pp. 1225-1228 ◽  
Author(s):  
Chun Xia Hou ◽  
Er Hua Zhang

Pipeline leak lead to huge economic losses and environmental pollution. Leak detection system based on single sensor negative pressure wave often causes false alarm. In this paper the double sensor method is adopted to exclude false alarm by determining the propagation direction of the pressure wave. In order to remove the inverse coherent interference caused by pump running, the phase difference of primary low frequency component is used to identify the sign of the time delay between the double sensors. The experiment shows the mothod is effective.


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