The objectives of the Fiber-Optic Leak-Detection (FOLD) project, carried out in Verneuil-en-Halatte, France, were to assess the capability of fiber-optic sensing to detect a small gaseous leakage on a buried pipe, give guidelines regarding the best deployment positions of the fiber along the pipe, compare the performance of several methodologies, and assess the impact of the fiber-optic length on the detection performance.
The 30-m-long pipe used for the testing campaign was typical of those used for gas transportation. It was made of steel and had an internal diameter of 390 mm. As are many in-service pipelines installed during the last century, it was originally coated with coal-tar enamel. This coating was removed before burying the pipe.
All leakages were simulated from the external surface of the pipe. As opposed to the real conditions, this pipe was not filled with pressurized gas but was rather used as a simple cylindrical envelope aimed at accommodating all lines feeding the different leakages with gas. There were 12 nozzle orifices on the pipe, thereby permitting investigation of four different release diameters (1, 3, 5, and 7 mm) and three different release directions (upward, sideways, and downward).
For ease of tracking, each row of nozzle orifices along the pipe was attributed to a given release diameter. In addition, to avoid any important deterioration of the soil that may influence the experimental results between two neighboring orifices, the following sequence was adopted for the orifices: 1, 5, 3, and 7 mm. The first and last rows were located 5 m from the ends of the pipe. All rows were equally distributed along the remaining distance of the pipe....
Fiber-Optic Leak-Detection Project
01 April 2017