Abstract

The Distributed Temperature Sensing (DTS) technique using an optical fiber sensor is a relatively new method in temperature logging.The key technique is optical time domain reflectometry (OTDR). A laser pulse is launched into an optical fiber. As the pulse passes through the fiber, energy is lost owing to scattering. The intensity of the backscattered light decays exponentially with time, given uniform losses within the fiber. Therefore, knowing the speed of the light in the fiber, it is possible to convert this intensity against distance. Among the scattered light components, Raman scattering due to molecular vibrations is temperature sensitive. Raman back-scattering is used for distributed temperature sensing (DTS), while Brillouin waves are used for distributed temperature and strain sensing (DTSS).