Feeling the Heat - Optical Fibers for Harsh Environments

With a growing need to monitor processes in harsh environments accurately, optical fibers are becoming an essential element within monitoring systems both as the communication line and as the sensing element.

Optical fiber sensors have been widely adopted into a range of sensing technologies including discrete and continuous temperature, pressure and strain sensors often used in relatively benign environments. Typically these sensors have been used in pipeline monitoring, perimeter monitoring, heat detection and structural monitoring systems, all of which operate within the -45°C to + 85°C temperature range of a standard optical fiber.  Each of these technologies have competition from other types of sensors, primarly electronic sensors, so adoption rates have been relatively slow.

As industries push their sensing requirements into the high temperature environments in oil wells and nuclear reactors or into the tight coil requirements for hydrophones and seismic sensing geophones, optical fibers start to offer major technical benefits over electronic sensors.  Fibers can be designed to tolerate the high temperatures and pressures found in oil wells, they can be radiation tolerant for nuclear environments, are immune to the high levels of electro-magnetic interference (EMI) associated with large industrial machinery and they do not require electrical power at the sensing element - particularly important for subsea reliability.

High Temperature Fibers:

With the increasing difficulty of extracting oil and gas from wells and the ever growing demand for these fuels, fiber sensors are increasingly being used to enhance oil recovery. The downhole environment is extremely aggressive with temperatures exceeding 300°C in some applications and extremely high pressures around 20,000 psi often being observed.  For downhole applications, it is estimated that 75% of sensors are required to reach up to 150°C with a further 20% requiring a maximum temperature of 300°C. Temperature sensors are used to track the movement of gfluids within the oil well, particularly when using Steam Assisted Gravity Drainage (SAGD), and seismic sensors are used for monitoring hydro fracking processes.  In these environments electronic sensors regularly fail, giving significant advantage to fiber optic based sensors.

Smart Sensors

Geometrically, a polyimide coating is significantly smaller than a standard acrylate coating.  The polyimide coating around the glass cladding of the fiber typically has a thickness of only 10 µm in comparison to the 60 µm thick layer of acrylate coating around a standard optical fiber.  This gives polyimide coated fibers a very low profile and makes them particularly useful for embedding into structions for structure health monitoring.

Acoustic Fibers - Fibers for Small Coil Diameters

Fiber optic acoustic sensors find use in the oil and gas industry and in defence applications.  For the oil and gas industry, downhole seismic sensors, subsea permanent reservoir monitoring systems and towed arrays are used to monitor the extraction processes and to discover new oil reserves.  For defence, fiber optic hydrophones are used as highly sensitive passive listening devices ideal for stealthy depolyments and for strategic infrastructure security such as monitoring ports and military bases.

 

To download the full white paper and learn how the high NA of specialty singlemode fiber enable them to be coiled to 15 mm diameter or even less and how the reduced diameter of the fiber can increase the mechanical lifetime of the product -  click here

 

Fibercore Ltd offer a wide range of Specialty Singlemode Fibers:: 

HB Polarization Maintaining Fibers Specialty Singlemode Fibers Cables, Connectors, Cleaver & Other products Photosensitive Fibers  Er doped Fibers & EDFA Products

Other Rare-Earth Doped Fibers Cladding Pump Fibers & Components Test, Measurement & other Laboratory Services Development and Custom Fibers

 For more information on our products and services, or to discuss your specific fiber needs:

telephone +44 (0) 23 8076 9893 or Email sales@fibercore.com

We look forward to hearing from you!