Retrofiting Existing Optical Fiber Infrastructure to Mitigate Geohazard Risk: The TGP Case

Abstract

Optical fiber cables (OFC) are well known for their use in communications. They offer long distance and fast transmission rate capabilities. OFC are the perfect companion of hydrocarbon and water transport system as part of the physical layer of the communication services and SCADA of the operating companies. As an example, the TGP system has more than 1400 km of cables laid in its Right-of-Way (ROW) which are in use since the beginning of its operation in 2004. More recently OFC started to be used as sensors. In such applications, a communication cable (CC) can be turned into a continuous temperature sensor allowing for leak and erosion detection. A strain monitoring cable (SMC) can also be spliced to the CC for landslide and subsidence detection in selected areas. In the case of very large soil displacement, it is common to observe the strain induced on the CC. From what precedes, existing OFC infrastructures can be taken advantage of to retrofit pipelines with monitoring instrumentation. The current work describes how an existing CC is retrofitted to provide information about the TGP transport system’s integrity. When accurate monitoring of a landslide is required, a dedicated sensing cable is installed locally and connected to the CC. Elsewhere the CC is being measured to detect and locate events as erosion or landslide in position where the geohazard risk present lower probability. Such approach not only improves geohazard risk management, but it also indicates early sign of stress on the cable that can lead to its rupture, mitigating service interruption probability.