Fibers in the optical fiber sensors would react with water and hydrogen in permanent downhole measurement under the high temperature and pressure. This reaction would change the absorption loss of the fibers, which would affect the reliability of the measurement system. To analyze this problem, the course of hydroxyl penetrating through fibers was investigated. The source of penetrating hydroxyl was discussed. The penetration changes the chemical bond combination inner the fibers, which causes the increase of the absorption loss and the reduction of useful life of the fibers. The results show that at the wavelength of 1.38μm, when the content of the hydroxyl group is about 0.0001, the absorption loss can reach 33dB/km. The analyses also point out that carbon-coated fiber could increase the static fatigue resistance parameter, thus increasing the useful life of the fibers exponentially.

Date Published: 9 November 2010
PDF: 5 pages
Proc. SPIE 7853, Advanced Sensor Systems and Applications IV, 78533P (9 November 2010); doi: 10.1117/12.871652

Published in SPIE Proceedings Vol. 7853:
Advanced Sensor Systems and Applications IV
Brian Culshaw; Yanbiao Liao; Anbo Wang; Xiaoyi Bao; Xudong Fan; Lin Zhang, Editor(s)