FBGS’s Polarization Maintaining (PM)-DTG® sensing system was presented at the Offshore Technology Conference (OTC) Asia by Forsys-Subsea, highlighting its unique features and the advantageous test results of leak detection (LD) of Liquid Natural Gas (LNG), where the semi-distributed sensors were deployed within a flexible pipe.
The presentation reviews the spectrum and technological progression of the different modalities of LD including fiber optic. A specific consideration for deployment in this platform was given to a Raman-based DTS and the more favorable breed of DTG® sensors due to their:
- Ability to detect very small leaks.
- Increased speed of leak detection.
- Ability to precisely locate leak.
More specifically, PM-DTG® sensors offered additional advantages in overcoming the cross-sensitivity of strain and temperature normally experienced in the standard DTG® sensors. Analytically, the PM-DTG® exhibits two orthogonally-polarized and separated wavelength peaks, where their spectral location and separation contribute to an independent measurement of temperature and strain. Experimental test results of simulated field setup revealed strain-independent temperature measurements and a reaction time of LD of less than 20 seconds for a full temperature drop range and with a spatial leak resolution in direct function of sensors separation (0.5m). This opens up an opportunity for delivering precise temperature information along the flexible to warn operators at the very beginning of a leak event.
Figure: Flexible pipe that connects production facility to storage system (Courtesy Technip).
For more details on this topic and related sensors, please contact us at: info@FBGS.com
