Test on tiny leakage and insulating layer damage monitoring of buried oil pipelines using distributed optical fiber temperature sensor

The distributed fiber optical temperature sensing technique can conduct real-time online monitoring on the leakage of buried oil pipelines.At present, however, it is necessary to enhance the studies on the tiny leakage identification method, the temperature abnormality due to the damage of insulating layer, the relationship between the sensor locations and the monitoring performance and so on at home and abroad.In this paper, a set of test apparatus for monitoring the leakage of buried oil pipeline was designed.Then, the full-scale pipeline leakage was simulated to systematically study the effects of transported medium temperature, leakage flow rate, insulating layer destroying degree and sensor location on the monitoring performance of distributed optical fiber sensor.Finally, a real-time leakage identification method based on distributed temperature monitoring data was developed.It is indicated that the temperature difference between the inner medium and the outer soil is the critical parameter for leakage monitoring.The flow rate of the leakage has little impact on the monitoring results when inner pressure and temperature are determined.It is recommended to place the distributed optical fiber temperature sensors beneath the bottom of the pipeline so as to monitor the leakage at circumferential positions effectively.The B-value identification algorithm based on temperature monitoring time history data can effectively discriminate the leakage from the insulating layer damage, so its identification accuracy is higher.