Leak Detection (LD) in critical pipelines and fluid transfer systems is a key requirement for the future of the petroleum industry in terms of assuring the health and safety of personnel, the public, the environment, and assets. For the LNG industry, safe transfer of LNG between production facilities (e.g. FLNG), tankers, and storage systems is essential. Assurance of integrity and safety should be pursued continuously in these systems, and effective LD systems can act as an early warning, allowing for safe mitigation of risk.
Current pipeline LD systems typically use Computational Pipeline Monitoring techniques. However, these LD systems have limitations in terms of their achievable minimum leak detection threshold and detection timing issues requiring a different approach be developed.
One such approach that is attracting much attention is the utilization of Fiber Optic (FO) systems. These may provide lower leak detection thresholds, shorter detection time coupled with extended range detection monitoring of long, e.g. 400+ m flexibles. FO Digital Temperature Sensors (DTS) have already been used for temperature measurements on flexible pipes and pipelines over several kilometers long. In Situ LD systems may possibly allow earlier detection of small leaks that are outside the capability of currently available systems. Being able to detect leaks with a real time LD may be very advantageous. This paper presents recent developments in design, integration, and testing of FO systems, which can provide detection of leaks in offshore pipelines and flexibles.
The use of FO sensing for offshore pipeline leak detection is still in its infancy and is emerging for cryogenic flexibles. New LD technologies are being developed for improving not only sensitivity, but, also how to reliably and economically deploy the system in situ in a LNG Flexible.
Several FO sensing technologies, including Raman, Brillouin and Fiber Bragg Grating (FBG) are under evaluation for Technip LNG flexibles. A quantitative/qualitative comparison of available FO solutions including deployment considerations in a flexible are discussed and presented in this paper.
What else can be done with this system? Other potential uses are to monitor stress or strain along the entire length of the pipe, provide a continuous temperature measurement, flexibles shape, etc. This type of monitoring may be coupled with Computational Fluid Dynamic (CFD) models to improve integrity and safety predictions.