The use of optical fibers in the oil and gas industry is becoming more viable for several permanent monitoring applications, such as distributed temperature sensing (DTS) and optical pressure transducers. However, long-term performance of fibers, especially at elevated temperatures, is still an issue yet to be fully resolved. This problem is critically important in steam-assisted gravity drainage (SAGD) applications, where wells operate in extreme conditions of high temperatures, often exceeding 250°C, as well as in high pressures within a hydrogen-rich environment.

Optical fiber performance is seriously affected by many factors, including:

  • Hydrogen ingression

  • Thermal resistance of the materials

  • Mechanical resistance of the fiber

Exposure of optical fibers to hydrogen changes the performance of the fibers through what is referred to in the industry as "hydrogen aging" or "hydrogen darkening." Hydrogen darkening is increased absorption or light loss due to various chemical species in the glass fiber resulting from the presence of hydrogen.

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